WO2015076076A1 - フェライト粒子並びにそれを用いた電子写真現像用キャリア及び電子写真用現像剤 - Google Patents
フェライト粒子並びにそれを用いた電子写真現像用キャリア及び電子写真用現像剤 Download PDFInfo
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- WO2015076076A1 WO2015076076A1 PCT/JP2014/078679 JP2014078679W WO2015076076A1 WO 2015076076 A1 WO2015076076 A1 WO 2015076076A1 JP 2014078679 W JP2014078679 W JP 2014078679W WO 2015076076 A1 WO2015076076 A1 WO 2015076076A1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/0018—Mixed oxides or hydroxides
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/0018—Mixed oxides or hydroxides
- C01G49/0036—Mixed oxides or hydroxides containing one alkaline earth metal, magnesium or lead
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/0018—Mixed oxides or hydroxides
- C01G49/0063—Mixed oxides or hydroxides containing zinc
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/0018—Mixed oxides or hydroxides
- C01G49/0072—Mixed oxides or hydroxides containing manganese
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/10—Developers with toner particles characterised by carrier particles
- G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
- G03G9/1075—Structural characteristics of the carrier particles, e.g. shape or crystallographic structure
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/10—Developers with toner particles characterised by carrier particles
- G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
- G03G9/108—Ferrite carrier, e.g. magnetite
- G03G9/1085—Ferrite carrier, e.g. magnetite with non-ferrous metal oxide, e.g. MgO-Fe2O3
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/10—Developers with toner particles characterised by carrier particles
- G03G9/113—Developers with toner particles characterised by carrier particles having coatings applied thereto
- G03G9/1132—Macromolecular components of coatings
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/10—Developers with toner particles characterised by carrier particles
- G03G9/113—Developers with toner particles characterised by carrier particles having coatings applied thereto
- G03G9/1132—Macromolecular components of coatings
- G03G9/1135—Macromolecular components of coatings obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- G03G9/1136—Macromolecular components of coatings obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon atoms
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
- H01F1/36—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/10—Solid density
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
Definitions
- the present invention relates to a ferrite particle, an electrophotographic developer carrier and an electrophotographic developer using the same.
- a toner is attached to an electrostatic latent image formed on the surface of a photosensitive member to make a visible image, and the visible image is formed on a sheet. After being transferred to, etc., it is fixed by heating and pressing.
- a so-called two-component developer including a carrier and a toner is widely used as a developer from the viewpoint of high image quality and colorization.
- the carrier and the toner are stirred and mixed in the developing device, and the toner is charged to a predetermined amount by friction. Then, a developer is supplied to the rotating developing roller, a magnetic brush is formed on the developing roller, and the toner is electrically moved to the photosensitive member via the magnetic brush, so that an electrostatic latent image on the photosensitive member can be formed. Visualize.
- the carrier after the toner movement remains on the developing roller and is mixed with the toner again in the developing device. For this reason, as the characteristics of the carrier, magnetic characteristics for forming a magnetic brush, charging characteristics for imparting a desired charge to the toner, and durability in repeated use are required.
- a carrier in which the surfaces of magnetic particles such as magnetite and various ferrites are coated with a resin is generally used.
- the magnetic particles as the carrier core material are required to have good magnetic characteristics as well as good triboelectric charging characteristics for the toner.
- Various shapes of carrier core materials that satisfy such characteristics have been proposed (see, for example, Patent Documents 1 and 2).
- Patent Document 1 At least magnetic particles are contained, the average interval Sm of the irregularities on the magnetic particle surface, and the maximum height Ry of the magnetic particle surface are 3.6 ⁇ m ⁇ Sm ⁇ 8.0 ⁇ m and 0.5 ⁇ m.
- An electrostatic charge developing carrier satisfying ⁇ Ry ⁇ 1.0 ⁇ m has been proposed.
- Patent Document 2 discloses magnetic particles having a surface roughness Ra of 0.1 ⁇ m or more and 10 ⁇ m or less and a surface roughness Sm of 0.1 ⁇ m or more and 10 ⁇ m or less.
- JP 2012-168284 A JP 2011-141542 JP
- the proposed carrier may not be compatible with recent image forming apparatuses such as copying machines. That is, in an image forming apparatus that employs a non-contact developing system, an image forming apparatus that employs a hybrid developing system, a so-called high-speed image forming apparatus that can form 60 to 70 images per minute, and the like.
- the resin coated on the surface of the magnetic particles may be peeled off due to long-term use, resulting in problems such as carrier scattering.
- the amount of the coating resin is large, the charge charged by frictional charging is difficult to leak, and there is a possibility that the charge imparting ability to the toner is lowered and the memory image is caused by long-term use.
- the present invention has been made in view of such a conventional problem, and its purpose is to be stable over a long period of time even when the image forming speed is increased when used as a carrier of an electrophotographic image forming apparatus. And providing ferrite particles that can be used.
- Another object of the present invention is to provide a carrier for an electrophotographic developer and an electrophotographic developer capable of stably forming an image of good image quality even after long-term use.
- the inventors of the present application as a carrier core material for an electrophotographic image forming apparatus, have conducted extensive studies to obtain ferrite particles that can be used stably over a long period of time even when the image forming speed is increased. It was found that the degree of exposure of the ferrite particles to the surface greatly affects the charging stability when the surface is coated with a resin. That is, if the surface area of the ferrite particles covered with the resin is small and the exposed area of the ferrite particles is too large, the resistance of the ferrite particles themselves is lowered, which causes carrier scattering.
- the exposed area of the ferrite particles such as complete coating
- the charge charged by frictional charging is difficult to leak, resulting in a decrease in the ability to impart charge to the toner and causing a memory image.
- the resin coating the surface of the ferrite particles does not peel off as much as possible.
- the inventors of the present application pay attention to the shape of the ferrite particle surface coated with the resin, and the grain forming the irregular shape of the particle surface, that is, the difference between the so-called peak portion and trough portion of the crystal grain and the angle of the grain. Focused on the shape. Specifically, the maximum height Rz that is an index of the difference between the peak and valley portions of the grain, and the skewness Rsk that is an index of the degree of deviation of the uneven and peak regions of the particle surface. Pay attention. And the maximum height Rz and distortion degree Rsk of these elements were earnestly examined, and it was set as the following structures.
- the ferrite particles according to the present invention have a composition formula M X Fe 3-X O 4 (where M is at least one selected from the group consisting of Mg, Mn, Ca, Ti, Cu, Zn, Sr, Ni). Ferrite particles whose main component is a metal, a material represented by 0 ⁇ X ⁇ 1), the maximum height Rz of the particles is in the range of 1.40 to 1.90, and the distortion degree Rsk of the particles is ⁇ The range is from 0.25 to -0.07.
- an electrophotographic developing carrier characterized in that the surface of the ferrite particles described above is coated with a resin.
- an electrophotographic developer comprising the electrophotographic developer carrier described above and a toner.
- the ferrite particles according to the present invention have a specific uneven shape on the surface, when used as a carrier core material of an electrophotographic image forming apparatus, the ferrite particles are stable over a long period of time even if the image forming speed is increased. Can be used.
- the image forming speed can be increased and the image quality can be improved.
- FIG. 1 It is a schematic sectional drawing which shows one Embodiment of the ferrite particle which concerns on this invention. It is a schematic sectional drawing which shows one Embodiment of the carrier based on this invention which coat
- 2 is a SEM photograph of ferrite particles of Example 1.
- 4 is a SEM photograph of ferrite particles of Example 4.
- 4 is a SEM photograph of ferrite particles of Example 6.
- 4 is a SEM photograph of ferrite particles of Example 7.
- 4 is a SEM photograph of ferrite particles of Example 8.
- 4 is a SEM photograph of ferrite particles of Example 10.
- 4 is a SEM photograph of ferrite particles of Comparative Example 1.
- 4 is a SEM photograph of ferrite particles of Comparative Example 2.
- FIG. 1 shows a schematic cross-sectional view of a ferrite particle according to the present invention
- FIG. 2 shows a schematic cross-sectional view showing an embodiment of a carrier according to the present invention in which the ferrite particle surface shown in FIG. 1 is coated with a resin.
- a minute uneven shape is formed on the surface 12 of the ferrite particle 11.
- a concave portion 13 having a partially recessed shape and a convex portion 14 having a shape protruding relatively to the outer diameter side with respect to the concave portion 13 are formed.
- the minute uneven shape is exaggerated from the viewpoint of easy understanding.
- the maximum height Rz of the ferrite particles 11 is in the range of 1.40 to 1.90, and the degree of distortion Rsk is in the range of ⁇ 0.25 to ⁇ 0.07.
- Such a ferrite particle 11 has an appropriate uneven shape on the particle surface, specifically, an appropriate difference between the peak portion and the valley portion in the grain, and an appropriate ratio between the peak portion region and the valley portion region. Therefore, when the particle surface is coated with a resin, peeling of the coating resin due to long-term use is effectively suppressed. In addition, a certain amount of exposed area of the ferrite particles is secured, so that charges are appropriately leaked. Furthermore, the covering area by the resin that can maintain the charge amount even during long-term use is ensured. Therefore, it can be used stably over a long period of time.
- the particle size of the ferrite particles of the present invention is not particularly limited, but an average particle size of about several tens ⁇ m to several hundreds ⁇ m is preferable. Further, when the ferrite particles of the present invention are used as a carrier core material, a particle size of about several tens of ⁇ m is preferable, and the particle size distribution is preferably sharp.
- the ferrite particles of the present invention can be used in various applications, for example, electrophotographic developer carriers, electromagnetic wave absorbing materials, electromagnetic shielding material powders, rubber, fillers / reinforcing materials for plastics, paints, paints / adhesives It can be used as a matting material, filler, reinforcing material and the like. Among these, it is particularly preferably used as a carrier for electrophotographic development.
- the manufacturing method of the ferrite particles of the present invention is not particularly limited, but the manufacturing method described below is preferable.
- an Fe component raw material, an M component raw material, and, if necessary, an additive are weighed, put into a dispersion medium, and mixed to prepare a slurry.
- M is at least one metal element selected from divalent metal elements such as Mg, Mn, Ca, Ti, Cu, Zn, Sr, and Ni.
- Fe component material Fe 2 O 3 or the like is preferably used.
- M component raw material MnCO 3 , Mn 3 O 4 and the like can be used for Mn, and MgO, Mg (OH) 2 and MgCO 3 can be suitably used for Mg.
- the Ca component raw material at least one compound selected from CaO, Ca (OH) 2 , CaCO 3 and the like is preferably used.
- Sr strontium or its oxide
- metal strontium or its oxide can be preferably used as the Sr component raw material.
- Water is suitable as the dispersion medium used in the present invention.
- a binder, a dispersant, and the like may be blended in the dispersion medium, if necessary.
- polyvinyl alcohol can be suitably used as the binder.
- the binder content is preferably about 0.5 to 2 wt% in the slurry.
- a dispersing agent polycarboxylate ammonium etc. can be used conveniently, for example.
- the blending amount of the dispersant is preferably about 0.5 to 2 wt% in the slurry.
- the solid content concentration of the slurry is desirably in the range of 50 to 90 wt%. Further, before introducing the Fe component raw material and the M component raw material into the dispersion medium, if necessary, pulverization and mixing may be performed.
- the slurry prepared as described above is wet pulverized.
- wet grinding is performed for a predetermined time using a ball mill or a vibration mill.
- the average particle diameter of the raw material after pulverization is preferably 50 ⁇ m or less, more preferably 10 ⁇ m or less.
- the vibration mill or ball mill preferably contains a medium having a predetermined particle diameter.
- the material of the media include iron-based chromium steel and oxide-based zirconia, titania, and alumina.
- any of a continuous type and a batch type may be sufficient.
- the particle size of the pulverized product is adjusted depending on the pulverization time and rotation speed, the material and particle size of the media used, and the like.
- the pulverized slurry is spray-dried and granulated.
- the slurry is introduced into a spray dryer such as a spray dryer, and granulated into a spherical shape by spraying into the atmosphere.
- the atmospheric temperature during spray drying is preferably in the range of 100 to 300 ° C.
- a spherical granulated product having a particle size of 10 to 200 ⁇ m is obtained.
- the obtained granulated product has a sharp particle size distribution by removing coarse particles and fine powder using a vibration sieve or the like.
- the granulated material is put into a furnace heated to a predetermined temperature, and fired by a general method for synthesizing ferrite particles, thereby generating ferrite particles.
- the firing temperature is preferably in the range of 1000 ° C. to 1300 ° C.
- the rate of temperature rise up to the firing temperature is preferably in the range of 250 ° C./h to 500 ° C./h.
- the firing atmosphere preferably has an oxygen concentration in the range of 2% to 21%.
- the thickness of the granulated material filled in the tray be 100 mm or less.
- the fired product thus obtained is pulverized as necessary.
- the fired product is pulverized by a hammer mill or the like.
- the form of the granulation step may be either a continuous type or a batch type.
- classification may be performed in order to make the particle size in a predetermined range.
- a classification method a conventionally known method such as air classification or sieve classification can be used.
- the particle size may be aligned within a predetermined range with a vibration sieve or an ultrasonic sieve.
- the powder (baked product) after classification may be heated in an oxidizing atmosphere to form an oxide film on the particle surface to increase the resistance of the ferrite particles (high resistance treatment).
- the oxidizing atmosphere may be either an air atmosphere or a mixed atmosphere of oxygen and nitrogen.
- the heating temperature is preferably in the range of 200 to 800 ° C., more preferably in the range of 250 to 600 ° C.
- the heating time is preferably in the range of 0.5 hours to 5 hours.
- the ferrite particles of the present invention produced as described above are used as a carrier for electrophotographic development
- the ferrite particles can be used as they are as a carrier for electrophotographic development.
- the surface is coated with a resin.
- FIG. 2 is a schematic cross-sectional view showing an embodiment of a carrier according to the present invention in which the surfaces of ferrite particles are coated with a resin.
- the carrier 15 is formed by covering the surface 12 of the ferrite particle 11 with a resin 16 thinly.
- the particle size of the carrier 15 is almost the same as that of the ferrite particle 11.
- the surface 17 of the carrier 15 is almost entirely covered with the resin 16, but the surface 12 of the ferrite particle 11 itself is exposed in a part of the region 18.
- resins can be used to coat the surface of the ferrite particles, such as polyethylene, polypropylene, polyvinyl chloride, poly-4-methylpentene-1, polyvinylidene chloride, ABS (acrylonitrile-butadiene-styrene).
- resins polystyrene, (meth) acrylic resins, polyvinyl alcohol resins, polyvinyl chloride-based, polyurethane-based, polyester-based, polyamide-based, polybutadiene-based thermoplastic elastomers, fluorine silicone-based resins, and the like.
- a resin solution or dispersion may be applied to the ferrite particles.
- Solvents for the coating solution include aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ether solvents such as tetrahydrofuran and dioxane; ethanol, propanol, and butanol Alcohol solvents such as ethyl cellosolve, cellosolve solvents such as butyl cellosolve; ester solvents such as ethyl acetate and butyl acetate; amide solvents such as dimethylformamide and dimethylacetamide, etc. .
- the concentration of the resin component in the coating solution is generally within the range of 0.001 wt% to 30 wt%, particularly 0.001 wt% to 2 wt
- a spray drying method for example, a fluidized bed method, a spray drying method using a fluidized bed, an immersion method, or the like can be used.
- the fluidized bed method is particularly preferable in that it can be efficiently applied with a small amount of resin.
- the resin coating amount can be adjusted by the amount of resin solution sprayed and the spraying time.
- the particle diameter of the carrier is generally preferably in the range of 10 ⁇ m to 200 ⁇ m, particularly in the range of 10 ⁇ m to 50 ⁇ m in terms of volume average particle diameter.
- the electrophotographic developer according to the present invention is obtained by mixing the carrier and toner prepared as described above.
- the mixing ratio of the carrier and the toner is not particularly limited, and may be determined as appropriate based on the developing conditions of the developing device to be used.
- the toner concentration in the developer is preferably in the range of 1 wt% to 15 wt%.
- the toner density is less than 1 wt%, the image density becomes too thin, and when the toner density exceeds 15 wt%, the toner scatters in the developing device, and the toner adheres to the background portion such as in-machine dirt or transfer paper. This is because there is a risk of occurrence.
- a more preferable toner concentration is in the range of 3 wt% to 10 wt%.
- toner produced by a conventionally known method such as a polymerization method, a pulverization classification method, a melt granulation method, or a spray granulation method can be used.
- a binder resin containing a thermoplastic resin as a main component and containing a colorant, a release agent, a charge control agent and the like can be suitably used.
- the particle diameter of the toner is preferably in the range of 5 ⁇ m to 15 ⁇ m, more preferably in the range of 7 ⁇ m to 12 ⁇ m, as a volume average particle diameter measured by a Coulter counter.
- a modifier may be added to the toner surface.
- the modifier include silica, alumina, zinc oxide, titanium oxide, magnesium oxide, polymethyl methacrylate and the like. These 1 type (s) or 2 or more types can be used in combination.
- a conventionally known mixing device can be used for mixing the carrier and the toner.
- a Henschel mixer, a V-type mixer, a tumbler mixer, a hybridizer, or the like can be used.
- Example 1 Ferrite particles were produced by the following method. As starting materials, 10.75 kg of Fe 2 O 3 , 4.38 kg of Mn 3 O 4 , 0.35 kg of MgO, and 0.019 kg of SrCO 3 are dispersed in 5.10 kg of pure water and reduced. 62 g of carbon black as an agent, 93 g of an ammonium polycarboxylate dispersant as a dispersant, and 33 g of polyvinyl alcohol as a binder were added to obtain a mixture. This mixture was pulverized by a wet ball mill (media diameter 2 mm) to obtain a mixed slurry.
- This mixed slurry was sprayed into hot air of about 130 ° C. with a spray dryer to obtain a dry granulated product having a particle size of 10 ⁇ m to 100 ⁇ m. From this granulated product, coarse particles having a particle size exceeding 100 ⁇ m were removed using a sieve screen.
- the granulated product was put into an electric furnace, heated to 1200 ° C. over 2.5 hours, and then held at 1200 ° C. for 3 hours for firing. At this time, the oxygen concentration in the electric furnace was 21% (atmosphere), and the thickness of the granulated material in the tray was 30 mm.
- the obtained fired product was pulverized with a hammer mill and then classified using a vibration sieve to obtain ferrite particles having an average particle size of 35.2 ⁇ m.
- FIG. 3 shows an SEM photograph of the ferrite particles of Example 1.
- Example 1 the surface of the ferrite particles of Example 1 obtained in this way was coated with a resin to produce a carrier of Example 1.
- a resin 450 parts by weight of a silicone resin and 9 parts by weight of (2-aminoethyl) aminopropyltrimethoxysilane were dissolved in 450 parts by weight of toluene as a solvent to prepare a coating solution.
- This coating solution was applied to 50000 parts by weight of the ferrite particles of Example 1 using a fluid bed type coating apparatus, and heated in an electric furnace at a temperature of 300 ° C. to obtain a carrier of Example 1.
- carriers were obtained in the same manner for all of the examples and comparative examples.
- the obtained carrier and a toner having an average particle diameter of about 5.0 ⁇ m were mixed for a predetermined time using a pot mill to obtain a two-component electrophotographic developer according to Example 1.
- developers were obtained in the same manner for all of the Examples and Comparative Examples. The obtained developer was evaluated on the actual machine described later. The evaluation results are shown in Table 2.
- FIG. 1 is a graph in which the values of the ferrite particles of Examples 1 to 10 and Comparative Examples 1 to 3 are plotted, where the vertical axis represents the degree of distortion Rsk of the particles and the horizontal axis represents the maximum height Rz of the particles. Indicates.
- volume average particle diameter The measurement of the volume average particle diameter was performed using Microtrack, Model 9320-X100 manufactured by Nikkiso Co., Ltd.
- the maximum height Rz and the skewness Rsk of the ferrite particles were measured as follows. Using an ultra-deep color 3D shape measurement microscope (“VK-X100” manufactured by Keyence Corporation), the surface was observed with a 100 ⁇ objective lens. Specifically, first, ferrite particles are fixed to an adhesive tape with a flat surface, the measurement field of view is determined with a 100 ⁇ objective lens, the focus is adjusted to the adhesive tape surface using the autofocus function, and the auto shooting function was used to capture the three-dimensional shape of the ferrite particle surface. Each parameter was measured using software VK-H1XA attached to the apparatus.
- FIG. 13 shows a schematic view of the surface of the extracted ferrite particles.
- a roughness curve corresponding to a line segment when a line segment 23 having a length of 15.0 ⁇ m in the horizontal direction is drawn on the central portion of the surface 22 of the ferrite particle 21 and 10 parallel lines are added at intervals of four lines above and below the segment 23. Were taken out in total.
- the upper ten line segments 24a and the lower ten line segments 24b are simply shown.
- the extracted roughness curve has a certain curvature as the background. For this reason, as a background correction, an optimal quadratic curve was fitted and correction subtracted from the roughness curve was performed. In this case, the cutoff value ⁇ s was 0.25 ⁇ m, and the cutoff value ⁇ c was 0.08 mm.
- the maximum height Rz was calculated as the sum of the highest mountain height and the deepest valley depth in the roughness curve.
- skewness Rsk was calculated by applying a roughness curve to the equation shown in the following equation (1).
- Rn represents a difference from the average line of the n-th peak or valley at the reference length of 15 ⁇ m, and the root mean square height Rq is obtained by the following formula (2).
- the obtained skewness Rsk indicates that the larger the value is, the bias is toward the region located in the valley.
- the root mean square inclination angle R ⁇ q of the ferrite particles was also calculated.
- the roughness curve was calculated by applying the following equation (1).
- dRn / dXn indicates the local slope of the nth peak or valley at the reference length of 15.0 ⁇ m, and is basically obtained by the seven-point formula shown in the following formula (4).
- the obtained root mean square inclination angle R ⁇ q indicates that the greater the value, the greater the inclination.
- the average particle diameter of the ferrite particles used for the analysis was limited to 32.0 to 34.0 ⁇ m. In this way, by limiting the average particle diameter of the ferrite particles to be measured to a narrow range, it is possible to reduce an error due to a residue generated during curvature correction. In addition, the average value of 30 particles was used as the average value of each parameter.
- the ferrite particles according to the present invention have a specific uneven shape on the surface, when used as a carrier core material of an electrophotographic image forming apparatus, the ferrite particles are stable over a long period of time even if the image forming speed is increased. Can be used and useful.
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Abstract
Description
フェライト粒子を下記方法で作製した。出発原料として、10.75kgのFe2O3と、4.38kgのMn3O4と、0.35kgのMgOと、0.019kgのSrCO3とを純水5.10kg中に分散し、還元剤としてカーボンブラックを62g、分散剤としてポリカルボン酸アンモニウム系分散剤を93g、バインダーとしてポリビニルアルコールを33g添加して混合物とした。この混合物を湿式ボールミル(メディア径2mm)により粉砕処理し、混合スラリーを得た。
表1に示す出発原料及び配合量、焼成温度で実施例1と同様にしてフェライト粒子を作製した。そして、実施例1と同様にして各物性を測定した。表2に測定結果をまとめて示す。また、図4~図8に実施例4、6,7,8,10のフェライト粒子のSEM写真を示す。さらに、図9~図11に比較例1~3のフェライト粒子のSEM写真を示す。また、図12に、縦軸として粒子の歪度Rskをとり、横軸として粒子の最大高さRzをとって、実施例1~10及び比較例1~3のフェライト粒子の値をプロットしたグラフを示す。
体積平均粒径の測定については、日機装株式会社製のマイクロトラック、Model9320-X100を用いて実施した。
また、表2中の磁気的特性を示す磁化の測定については、VSM(東英工業株式会社製、VSM-P7)を用いて、飽和磁化σs及び磁化σ1k、残留磁化σr、保磁力Hcをそれぞれ測定した。
フェライト粒子の見掛け密度はJIS Z 2504に準拠して測定した。
フェライト粒子の最大高さRz及び歪度Rskを次のように測定した。超深度カラー3D形状測定顕微鏡(「VK-X100」株式会社キーエンス製)を用い、100倍対物レンズで表面を観察して求めた。具体的には、まず、表面の平坦な粘着テープにフェライト粒子を固定し、100倍対物レンズで測定視野を決定した後、オートフォーカス機能を用いて焦点を粘着テープ面に調整し、オート撮影機能を用いてフェライト粒子表面の3次元形状を取り込んだ。
各パラメータの測定には、装置付属のソフトウェアVK-H1XAを用いて行った。まず、前処理として、得られたフェライト粒子の表面の3次元形状から解析に用いる部分の取り出しを行った。図13に、取り出されたフェライト粒子表面の概略図を示す。フェライト粒子21の表面22の中央部分に長さ15.0μmの水平方向に延びる線分23を引き、その上下に4本間隔で10本ずつ平行線を追加した場合の線分上にあたる粗さ曲線を、計21本分取り出した。図13において、上側の10本の線分24a、下側の10本の線分24bを簡略的に示している。
現像域で交流バイアスを印加するよう改良したデジタル反転現像方式を採用する70枚機(70cpm)相当の評価機に、作製した現像剤500gを投入し、文字およびベタ黒画像を1000枚印刷し、1000枚目における用紙のベタ画像部におけるメモリ画像について目視で評価した。評価基準は下記の通りである。
「◎」:ベタ画像を良好に再現している場合
「○」:ごくわずかに擦れがあるが、実使用上問題のない場合
「△」:わずかに印字が読み取れる場合
「×」:印字が鮮明に読み取れる場合
12 粒子表面
13 凹部
14 凸部
15 キャリア
16 樹脂
Claims (3)
- 組成式MXFe3-XO4(但し、MはMg,Mn,Ca,Ti,Cu,Zn,Sr,Niからなる群より選ばれる少なくとも1種の金属,0<X<1)で表される材料を主成分とするフェライト粒子であって、
粒子の最大高さRzが1.40~1.90の範囲であり、粒子の歪度Rskが-0.25~-0.07の範囲であることを特徴とするフェライト粒子。 - 請求項1記載のフェライト粒子の表面を樹脂で被覆したことを特徴とする電子写真現像用キャリア。
- 請求項2記載の電子写真現像用キャリアとトナーとを含む電子写真用現像剤。
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EP14863704.4A EP3075710B1 (en) | 2013-11-25 | 2014-10-29 | Ferrite particles, carrier for electrophotographic development using same, and developer for electrophotography |
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JP6547229B2 (ja) | 2016-03-31 | 2019-07-24 | パウダーテック株式会社 | フェライト粒子、樹脂組成物及び樹脂フィルム |
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