JP5597487B2 - Manufacturing method of recycled carrier - Google Patents

Description

  The present invention relates to a method for producing a regenerated carrier for electrophotographic developer (hereinafter sometimes simply referred to as “regenerated carrier”), a regenerated carrier, a carrier core material of regenerated carrier, an electrophotographic developer, and an electrophotographic developer. The present invention relates to a manufacturing method, and in particular, a manufacturing method of a regenerated carrier used for an electrophotographic developer used in a copying machine, an MFP (Multifunctional Printer), etc., a regenerated carrier, a carrier core material of a regenerated carrier, an electrophotographic developer, and The present invention relates to a method for producing an electrophotographic developer.

  In a copying machine, MFP, etc., as a dry development method in electrophotography, a one-component developer using only toner as a component of developer and a two-component developer using toner and carrier as components of developer are provided. is there. In any of the development methods, toner charged to a predetermined charge amount is supplied to the photoreceptor. Then, the electrostatic latent image formed on the photosensitive member is visualized with toner and transferred to a sheet. Thereafter, the visible image with toner is fixed on the paper to obtain a desired image.

  Here, the development in the two-component developer will be briefly described. A predetermined amount of toner and a predetermined amount of carrier are accommodated in the developing device. The developing device includes a rotatable magnet roller in which a plurality of S poles and N poles are alternately provided in the circumferential direction, and a stirring roller that stirs and mixes the toner and the carrier in the developing device. A carrier made of magnetic powder is carried by a magnet roller. A linear magnetic brush made of carrier particles is formed by the magnetic force of the magnet roller. A plurality of toner particles adhere to the surface of the carrier particles by frictional charging by stirring. Toner is supplied to the surface of the photoconductor by rotating the magnet roller so that the magnetic brush is applied to the photoconductor. In a two-component developer, development is performed in this way.

  In these days, the above-mentioned carrier is mainly composed of a core material, that is, a carrier core material constituting a core portion, and a coating resin provided so as to cover the surface of the carrier core material. It is. The carrier, which is a constituent material of the two-component developer, has a toner charging function for efficiently charging the toner by frictional charging by stirring, a toner transporting capability for appropriately transporting and supplying the toner to the photosensitive member, and a photosensitive toner. Various functions are required, such as a charge transfer speed that quickly leaks residual charges on the carrier surface after being transferred to the body.

  At the time of development, that is, at the time of image formation, since toner in the developing device is sequentially consumed by fixing to paper, a new amount corresponding to the amount consumed from the toner hopper attached to the developing device. Toner is supplied into the developing device as needed. On the other hand, since the carrier is not consumed by development, the same carrier is repeatedly used in the developing device.

  Here, the performance of the carrier deteriorates as the usage time becomes longer. Specifically, if the time for use in the developing device becomes long, the chance of stirring contact between carriers or between the carrier and the wall surface of the developing device increases, and the coating resin comes from the surface of the carrier core material. The toner component is peeled off locally or the toner component is fixed to the carrier surface by heat. If it does so, the performance as a carrier will deteriorate by the influence of the part which peeled off and the part which adhered. Therefore, a developer having such a carrier as a constituent material is provided with a lifetime from the viewpoint of maintaining image quality. The developer that has reached the end of its life is collected from the developing device, and a new developer is introduced. Generally, the developer that has reached the end of its life is disposed of.

  In recent years, from the viewpoint of ecology, it is required to reuse the used developer that has reached such a lifetime. In other words, after collecting the developer, it is required that the carrier that has reached the end of its life can be reused as a recycled product, mixed with new toner and reused as a developer. A technique relating to such a reusable reproduction carrier is disclosed in Japanese Patent Laid-Open No. 7-72665 (Patent Document 1).

JP 7-72665 A

  According to the carrier regeneration method disclosed in Patent Document 1, primary heat treatment is performed on the collected used Mn—Zn-based ferrite carrier at a temperature higher than the temperature at which the adhered toner and the coating resin can be removed and lower than 500 ° C. After that, secondary heat treatment is performed in a reducing atmosphere at 400 to 600 ° C.

  However, according to such a regeneration method, stepwise heat treatment such as primary heating and secondary heating is required, and the number of treatment steps increases. If it does so, there exists a possibility of leading to the increase in the energy cost in manufacture of a reproduction | regeneration carrier.

  An object of the present invention is to provide a method for manufacturing a regenerative carrier that can be manufactured at low cost.

  Another object of the present invention is to provide a regenerative carrier that can be manufactured at low cost.

  Still another object of the present invention is to provide a carrier core material for a regenerated carrier that can be manufactured at low cost.

  Still another object of the present invention is to provide an electrophotographic developer that can be produced at low cost.

  Still another object of the present invention is to provide a method for producing an electrophotographic developer that can be produced at low cost.

  In manufacturing the regenerated carrier, the inventors of the present application first reduce the cost of a carrier core material that does not deteriorate the electrical properties and magnetic properties of the carrier core material itself that constitutes the carrier among the collected used developer. I thought about getting. That is, a used carrier core material having a function equivalent to that of an unused carrier core material before being newly coated with a resin is obtained at low cost from the collected developer. The obtained used carrier core material was newly coated with a resin to obtain a regenerated carrier.

  Here, when the carrier core material is obtained from the used carrier component separated from the collected developer, the process is relatively simple. Specifically, it was considered not to repeat the stepwise heat treatment or perform the treatment using a liquid such as an organic solvent.

That is, the method for producing a regenerative carrier according to the present invention has a general formula: M _x Fe _3-x O ₄ (0 ≦ x ≦ 1, where M is Mg, Mn, Ca, Ti, Cu, Zn, Sr, A core composition represented by a core composition represented by at least one metal selected from the group consisting of Ni) as a main component of a carrier core material, a coating carrier whose surface is coated with a resin, and a developer composed of toner, and again A method for producing a regenerated carrier that regenerates a usable carrier, the step of separating a carrier component from a developer, and the separated carrier component within a temperature range of 1000 ° C. to 1250 ° C. in an inert gas atmosphere. A heat treatment step for performing heat treatment; and a resin coating step for coating the surface of the obtained carrier core material component with resin after the heat treatment step.

  In the regenerated carrier having the above-described configuration, the carrier component is separated from the used developer, and heat treatment is performed in a temperature range of 1000 ° C. to 1250 ° C. in an inert gas atmosphere. By carrying out like this, the resin component containing coating resin can be removed from the surface of the isolate | separated carrier component by one heat processing process. Moreover, according to such a heat treatment process, it is possible to prevent the electrical characteristics and magnetic characteristics as the carrier core material from being deteriorated. The surface of the carrier core component subjected to such heat treatment can be coated with a coating resin to produce a new product, that is, a regenerated carrier having the same performance as an unused carrier. Therefore, a regenerated carrier can be manufactured at low cost.

  In the heat treatment step, the oxygen concentration is preferably 10000 ppm or less. That is, preferably, in the heat treatment step, the carrier component is heat-treated in an inert gas atmosphere having an oxygen concentration of 10,000 ppm or less. By doing so, a regenerated carrier equivalent to an unused carrier can be manufactured more reliably.

In the heat treatment step, N ₂ gas may be used as the inert gas. Such a gas is relatively easy to obtain, easy to handle, and can be manufactured at a lower cost.

  The developer may be a used developer that has been used for a predetermined period as an electrophotographic developer.

In another aspect of the present invention, the regenerated carrier has the general formula: M _x Fe _3-x O ₄ (0 ≦ x ≦ 1, where M is Mg, Mn, Ca, Ti, Cu, Zn, Sr, Ni A core composition represented by at least one metal selected from the group consisting of: a coating carrier whose main component is a carrier core, a resin coated on the surface of the carrier, and a developer composed of toner; A regenerated carrier that is regenerated so that the carrier component is separated from the developer, and the separated carrier component is heat-treated in an inert gas atmosphere within a temperature range of 1000 ° C. to 1250 ° C. The surface of the obtained carrier core component is coated with a resin.

  Such a regenerated carrier can also be manufactured at low cost.

In yet another aspect of the present invention, the carrier core material of the regenerated carrier has a general formula: M _x Fe _3-x O ₄ (0 ≦ x ≦ 1, where M is Mg, Mn, Ca, Ti, Cu, Development composed of a coating carrier having a core composition represented by (at least one metal selected from the group consisting of Zn, Sr, and Ni) as a main component of the carrier core material, the surface of which is coated with a resin, and toner A carrier core material of a regenerated carrier regenerated so that it can be used again from the agent, wherein the carrier component is separated from the developer, and the separated carrier component is heated at a temperature of 1000 ° C. to 1250 ° C. in an inert gas atmosphere. It is obtained by performing heat treatment within the range.

  Such a carrier core material of the regenerated carrier can also be manufactured at a low cost.

  In still another aspect of the present invention, an electrophotographic developer includes a regenerated carrier having the above-described configuration and a toner.

  Such an electrophotographic developer can be produced at low cost.

  In still another aspect of the present invention, a method for producing an electrophotographic developer includes a step of mixing a regenerated carrier having the above-described structure and a toner at a predetermined ratio.

  Such a method for producing an electrophotographic developer can also be produced at low cost.

  The method for producing a regenerated carrier, the regenerated carrier, the carrier core material of the regenerated carrier, the electrophotographic developer, and the method for producing the electrophotographic developer according to the present invention can be produced at low cost.

It is an electron micrograph which shows the external appearance of the carrier core material of an unused carrier. It is an electron micrograph which shows the external appearance of an unused carrier. 4 is a flowchart showing typical steps in a method for manufacturing a regenerative carrier according to an embodiment of the present invention. It is an electron micrograph which shows the external appearance of the carrier core material of a reproduction | regeneration carrier. It is an electron micrograph which shows the external appearance of a reproduction | regeneration carrier. It is an electron micrograph which shows the external appearance of the carrier core material which heat-processed at 500 degreeC in air atmosphere. It is an electron micrograph which shows the external appearance of the carrier core material which heat-processed at 500 degreeC in the air atmosphere, and also heat-processed at 600 degreeC in the reducing atmosphere.

Embodiments of the present invention will be described below with reference to the drawings. First, a preferable example of a manufacturing process of a carrier core material of an unused carrier will be described while exemplifying a case where Mn-based soft ferrite is used. As a soft ferrite used for a carrier core material according to the present invention, manganese ferrite is used. Various magnetic materials such as magnesium ferrite and manganese magnesium ferrite can be used. Specifically, the general formula: M _x Fe _3-x O ₄ (0 ≦ x ≦ 1, where M is selected from the group consisting of Mg, Mn, Ca, Ti, Cu, Zn, Sr, and Ni. The core composition represented by (at least one kind of metal) is the main component of the carrier core material. As the core composition, when x = 0 described above, magnetite (Fe ₃ O ₄ ) is shown.

(Formulation of raw material powder)
In preparing the raw materials for each component constituting soft ferrite, Mn ₃ O ₄ and MnCO ₃ were prepared as the Mn source, and Fe ₂ O ₃ was prepared as the Fe source. Each raw material is weighed so that the composition ratio of Mn and Fe in the soft ferrite corresponds to the intended composition ratio of soft ferrite. Furthermore, carbon black (hereinafter referred to as CB) used as a C source was weighed. These raw materials are mixed well and prepared. The mixing method may be ordinary mixing by using a mortar or the like. The blended CB is considered to be CO ₂ in the firing step described later.

When magnesium ferrite is selected as the ferrite, MgO, Mg (OH) ₂ and MgCO ₃ may be used as the Mg source, and Fe ₂ O ₃ may be used as the Fe source. Mn ₃ O ₄ and MnO as the Mn source, MgO, Mg (OH) ₂ and MgCO ₃ as the Mg source, and Fe ₂ O ₃ as the Fe source may be used. In addition to CB, polyvinyl alcohol (PVA), graphite, polyacrylamide, acetylene, and the like can be suitably used as the C source. And even if any raw material is used, each ferrite can be manufactured with the manufacturing process similar to the manufacturing process of the manganese ferrite demonstrated below.

(Crushing and granulating process)
The prepared raw material is mixed with water, and if necessary, a dispersing agent such as polycarboxylic acid is further mixed to form a slurry having a solid content concentration of about 60 to 90% by weight of the raw material, and this is wet with a ball mill or the like. Smash. By this wet pulverization, a finely pulverized raw material slurry is obtained. The raw material slurry is spray-dried with a spray dryer or the like, or granulated with a pelletizer, and dried into spherical pellets having a diameter of 10 to 500 μm.

(Baking process)
Next, the above-described spherical pellets are fired to form soft ferrite. At that time, firing is performed in an electric furnace at a temperature of 1000 to 1350 ° C. in a nitrogen gas atmosphere. In this firing treatment, the carbon compound in the raw material becomes CO ₂ , but if the carbon addition ratio is 0.5 to 2.0% by weight in terms of carbon element, within the range in which the spherical nature of the particles can be maintained. Since sinterability can be controlled, it is preferable.

(Sieving process)
The fired soft ferrite is pulverized by a pulverizer to obtain a pulverized powder, and the pulverized powder is classified or sieved to collect a powder having a predetermined particle size to obtain a carrier core material. Thereby, for example, a carrier core material having an apparent density of 2.0 to 2.8 g / cm ³ including soft ferrite particles having an average particle diameter of 20 to 100 μm, preferably about 35 μm is manufactured. Can do. In addition, the electron micrograph of the external appearance of the carrier core material 11 of the unused carrier thus obtained is shown in FIG.

(Resin coating process)
Next, a process for producing a carrier powder for electrophotographic developer (hereinafter referred to as a carrier), that is, a so-called unused carrier by performing resin coating on the obtained carrier core material will be described.

  When a carrier is produced by applying a resin coating to the carrier core material, the resin coating amount is preferably adjusted to 0.5 to 10.0% by weight of the total weight of the carrier core material. Various resins can be applied as the coating resin, such as acrylic resins, styrene resins, styrene-acrylic resins, olefin resins (polyethylene, chlorinated polyethylene, polypropylene, etc.), polyester resins (polyethylene terephthalate, polycarbonate, etc.) ), Unsaturated polyester resins, vinyl chloride resins, polyamide resins, polyurethane resins, epoxy resins, silicone resins, fluorine resins (polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, etc.), Examples thereof include phenolic resins, xylene resins, diallyl phthalate resins, and the like.

  In order to perform resin coating, the above-mentioned predetermined resin is generally diluted with a solvent and coated on the surface of the carrier core material. As the solvent, it is sufficient that the predetermined resin is soluble. When the predetermined resin is a resin soluble in an organic solvent, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, methanol, etc. should be used as the solvent. If the predetermined resin is a water-soluble resin or an emulsion type resin, water can be used.

  In order to coat the surface of the carrier core material with a predetermined resin diluted with an appropriate solvent, a dipping method, a spray method, a brush coating method, or the like can be applied. A carrier can be obtained by drying the carrier core material coated with a predetermined resin. In addition to resin coating by such a wet method, the carrier can also be obtained by a dry method in which a predetermined resin powder is adhered to the surface of the carrier core material.

  In any of the above-described wet method and dry method, it is preferable to bake a predetermined resin coated on the surface of the carrier core material. Therefore, it is preferable to bake a predetermined resin coated on the surface of the carrier core material by an external heating method or an internal heating method using a fixed or fluid electric furnace, a rotary electric furnace, a burner furnace, or the like. . Note that microwave baking is also possible. The baking temperature varies depending on the predetermined resin, but a temperature higher than the melting point or higher than the glass transition point is required. When the predetermined resin is a thermosetting resin or a condensation type resin, it is necessary to increase the temperature to a temperature at which the curing proceeds sufficiently.

  Here, the case where a silicone resin is selected as the predetermined resin and the carrier core material is coated will be specifically described as an example.

  First, the silicone resin is diluted with toluene. For example, the silicone resin is mixed so that the ratio of the silicone resin is 3% by weight of the total weight of the carrier core material, and this liquid and the carrier core material are put into a stirrer and stirred. . In this case, a curing agent is added as necessary. When the stirring and mixing are completed, the carrier core material coated with the resin solution is subjected to a heat treatment, for example, at 190 ° C. for 30 minutes, and the solvent is removed by drying. Next, the carrier core material coated with the resin after the heat treatment is subjected to a heat treatment of, for example, 170 to 280 ° C. × 3 hours using an oven or a tunnel furnace to perform a baking treatment of the silicone resin. This provides a carrier. In addition, the electron micrograph of the external appearance of the unused carrier 12 obtained in this way is shown in FIG.

  Then, the unused carrier thus obtained and a predetermined amount of toner are stirred and mixed to obtain an unused developer. The unused developer thus obtained is charged into a developing device in a predetermined amount, attached to a predetermined portion of the copying machine, and generally used until the end of its life.

  Next, a manufacturing method for manufacturing a regenerated carrier according to an embodiment of the present invention will be described. FIG. 3 is a flowchart showing typical steps in the method for manufacturing a regenerative carrier according to one embodiment of the present invention. A method for manufacturing a regenerative carrier according to an embodiment of the present invention will be described below with reference to FIG.

  First, used developer that has reached the end of its life is collected from a developing device provided in a copying machine or the like. The used developer means a developer that has been used in a predetermined copying machine or the like and has reached a set time or number of sheets as a lifetime.

  Then, the toner component is removed from the collected used developer to separate the carrier component (FIG. 3A). To remove the toner component, for example, an air blow method may be adopted, and the carrier component may be separated by removing the toner component from the developer, or the toner component may be removed by sieving to separate the carrier component. Also good. In this case, it is not necessary to completely separate the toner component and the carrier component, and a small amount of the toner component may remain and adhere to the carrier component.

  Next, heat treatment is performed on the separated carrier component (FIG. 3B). Here, the heat treatment step is a step of heat-treating the separated carrier component in a temperature range of 1000 ° C. to 1250 ° C. in an inert gas atmosphere. Specifically, the obtained carrier component is put into a furnace heated to 1000 ° C. to 1250 ° C. in an inert gas atmosphere, and heat treatment is performed for 3 hours.

  Here, although it is the temperature of heat processing, in order to prevent the possibility of sintering of the carrier core material of the reproduction | regeneration carrier at the time of heat processing, it shall be 1250 degrees C or less. Moreover, by setting it as 1000 degreeC or more, as it mentions later, the electrical characteristic and magnetic characteristic as a carrier core material of a reproduction | regeneration carrier can be prevented from falling.

  Further, the heat treatment time is 3 hours here, but it depends on the amount of the carrier component to be heat treated, etc., and may be any time as long as the resin component on the surface of the carrier component can be removed by the heat treatment. Depending on the amount of the carrier component, etc., it may be about 1 hour.

  The heat treatment is performed in an inert gas atmosphere, and the oxygen concentration in the inert gas atmosphere is preferably as low as possible. Specifically, the oxygen concentration may be 10000 ppm or less. In the process, a slight amount of oxygen is contained even in an inert gas atmosphere. That is, the atmosphere of an inert gas is a state in which an extremely small amount of oxygen, for example, 500 ppm or less of oxygen is inevitably contained.

  FIG. 4 is an electron micrograph showing the appearance of the carrier core material of the regenerated carrier according to one embodiment of the present invention. Referring to FIG. 4, the outer shape of the carrier core material 13 of the regenerative carrier according to one embodiment of the present invention is a substantially spherical shape. Further, the appearance properties are substantially the same as the appearance properties of the carrier core shown in FIG. The particle diameter of the carrier core material 13 of the regenerative carrier according to one embodiment of the present invention is about 35 μm as in the case of a new carrier that is a source of the regenerated carrier, that is, the carrier core material of an unused carrier. The above-mentioned particle diameter means a volume average particle diameter. Here, Nikkiso Co., Ltd. micro track, Model 9320-X100 was used for the measurement of the particle size.

  Next, a resin is coated on the carrier core material of the regenerated carrier thus obtained (FIG. 3C). Specifically, the carrier core material of the obtained regenerated carrier is coated with a silicone resin or the like as described above. In this way, a reproduction carrier according to an embodiment of the present invention is obtained.

  A regenerated carrier according to an embodiment of the present invention is a carrier core material obtained by the above-described method, which is newly coated with a thin resin, that is, with respect to the particle size. There is almost no change with the material. The surface of the regenerated carrier is almost completely covered with a resin by coating. About resin coating, it coats by the method similar to the method of coating resin to the carrier core material of an unused carrier. An electron micrograph of the appearance of the regenerated carrier 14 thus obtained is shown in FIG. The appearance properties of the regenerated carrier 14 are also substantially the same as the appearance properties of the unused carrier 12 shown in FIG.

  The developer using the regenerated carrier is produced by mixing the regenerated carrier and new toner at a predetermined ratio with an appropriate mixer. The outer shape of the toner is also substantially spherical. The toner is mainly composed of a styrene acrylic resin or a polyester resin, and contains a predetermined amount of pigment, wax or the like. Such a toner is manufactured by, for example, a pulverization method or a polymerization method. For example, a toner having a particle size of about 5 μm, which is about 1/7 of the particle size of the regenerated carrier, is used. Such a developer is used as an electrophotographic developer.

That is, the method for producing a regenerative carrier according to an embodiment of the present invention has a general formula: M _x Fe _3-x O ₄ (0 ≦ x ≦ 1, where M is Mg, Mn, Ca, Ti, Cu, Development composed of a coating carrier having a core composition represented by (at least one metal selected from the group consisting of Zn, Sr, and Ni) as a main component of the carrier core material, the surface of which is coated with a resin, and toner A method for producing a regenerated carrier that regenerates a reusable carrier from an agent, the step of separating the carrier component from the developer, and the carrier component separated at 1000 ° C. to 1250 ° C. in an inert gas atmosphere. A heat treatment step for performing heat treatment within a temperature range and a resin coating step for coating the surface of the obtained carrier core material component with resin after the heat treatment step are included.

  According to such a method for producing a regenerated carrier, the resin component including the coating resin can be removed from the surface of the separated carrier component in a single heat treatment step. Moreover, according to such a heat treatment process, it is possible to prevent the electrical characteristics and magnetic characteristics as the carrier core material from being deteriorated. Therefore, a regenerated carrier can be manufactured at low cost.

In addition, the regenerated carrier according to one embodiment of the present invention has a general formula: M _x Fe _3-x O ₄ (0 ≦ x ≦ 1, where M is Mg, Mn, Ca, Ti, Cu, Zn, Sr , At least one metal selected from the group consisting of Ni) as a main component of the carrier core material, a coating carrier whose surface is coated with a resin, and a developer composed of toner, Regenerated carrier that has been regenerated for use again, the carrier component is separated from the developer, and the separated carrier component is subjected to a heat treatment within a temperature range of 1000 ° C. to 1250 ° C. in an inert gas atmosphere. After the heat treatment, the surface of the obtained carrier core component is coated with a resin.

  Such a regenerative carrier can be manufactured at low cost.

Moreover, the carrier core material of the regenerative carrier according to one embodiment of the present invention has a general formula: M _x Fe _3-x O ₄ (0 ≦ x ≦ 1, where M is Mg, Mn, Ca, Ti, Cu , Zn, Sr, and Ni selected from the group consisting of Zn, Sr, and Ni) as a main component of the carrier core material, and a coating carrier whose surface is coated with a resin, and a toner. A carrier core material of a regenerated carrier regenerated from a developer so that it can be used again. The carrier component is separated from the developer, and the carrier component separated at 1000 ° C. to 1250 ° C. in an inert gas atmosphere. It is obtained by performing a heat treatment within the temperature range.

  Such a carrier core material of the regenerated carrier can also be manufactured at a low cost.

  An electrophotographic developer according to an embodiment of the present invention includes a regenerated carrier having the above-described configuration and a toner.

  Such an electrophotographic developer can also be manufactured at low cost.

  In addition, a method for producing an electrophotographic developer according to an embodiment of the present invention includes a step of mixing a recycled carrier having the above-described configuration and a toner at a predetermined ratio.

  Such a method for producing an electrophotographic developer can also be produced at low cost.

Example 1
First, as a new carrier, Mn ferrite manufactured by the following method is used as a carrier core material. Fe ₂ O ₃ and Mn ₃ O ₄ finely pulverized to a particle size of about 1 μm are prepared as carrier materials, and weighed so that the molar ratio is Fe ₂ O ₃ : Mn ₃ O ₄ = 65: 35. And mixed to obtain a mixed powder. The obtained mixed powder was poured into water containing 0.5% by weight of CB and 1.5% by weight of a dispersant (ammonium polycarboxylate dispersant) and stirred to obtain a slurry having a solid content concentration of 70% by weight. .

  This slurry was wet pulverized with a wet ball mill, and this wet pulverization operation was repeated three times to obtain a wet pulverized product. The wet pulverized product was further stirred and then sprayed with a spray dryer to produce a dry granulated product having a particle size of 10 to 100 μm.

  Here, coarse particles were separated from the dried granulated product using a sieve mesh having a mesh size of 75 μm. And the granulated product which isolate | separated this coarse grain was heated at 900 degreeC in air | atmosphere, and it calcined for 3 hours, Then, it baked at 1300 degreeC for 5 hours and made it ferrite in nitrogen atmosphere, and it was set as the baked product.

  The ferritized fired product was crushed with a hammer mill, and then fine powder was removed from the ferritized fired product using an air classifier.

  The fired product from which the fine powder has been removed is further passed through a vibration sieve and adjusted so that the volume average particle diameter (Dv) is 35.0 μm, and the carrier core material containing Mn—Fe based ferrite as the main component of the core composition. Got.

  On the other hand, a silicone resin (toluene Dow Corning SR-2411) was diluted with a solvent (toluene) so as to have a solid content of 20% by weight to prepare a silicone resin solution.

  The obtained carrier core material and a mixed resin solution obtained by adding alumina to a 3% by weight silicone resin solution with respect to the carrier core material were put into a dip coating apparatus, heated, and then heated and stirred at 240 ° C. for 2 hours. Then, a carrier core material surface coated with a resin was prepared.

Then, this new carrier was mixed with a predetermined amount of toner to obtain a new developer. Next, a predetermined amount of this new developer was put into a developing device provided in the copying machine, and the developer was used. After the developer that had been used for a predetermined period and reached the end of its life was collected as a used developer, the toner component was removed by air blowing to separate the toner component and the carrier component. About 1 kg of the separated carrier component, heat treatment was performed at 1000 ° C. for 3 hours in an electric furnace (muffle furnace). The atmosphere of the heat treatment in this case used N ₂ gas as an inert gas, and the oxygen concentration was 500 ppm or less. In addition, about oxygen concentration, the oxygen concentration in the atmosphere in a furnace was measured using the zirconia-type oxygen meter (Daiichi Heatken Co., Ltd. make, ECOAZ TB-II FS). Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the regenerated carrier thus heat-treated as Example 1. The same applies to the second and subsequent embodiments. After that, the carrier core material of the regenerated carrier was coated with a predetermined amount of alumina-containing silicone resin by a dip coating apparatus to obtain a regenerated carrier according to Example 1.

  Next, the resin-coated regenerated carrier according to Example 1 and the toner having a particle diameter of about 5 μm were mixed by a pot mill to produce a two-component electrophotographic developer A according to Example 1. Using the produced two-component electrophotographic developer, a 40-sheet machine adopting a digital reversal development method was used as an evaluation machine, and the carrier adhesion and the image gradation were evaluated.

(1) Evaluation of carrier adhesion:
Evaluation of carrier adhesion with respect to the two-component electrophotographic developer A was performed using a 40 sheet machine as an evaluation machine. Specifically, the level of carrier adhesion (white spots) on the image was then evaluated in four stages.

  (Double-circle): It is a level without a white spot in 10 sheets of A3 paper.

  A: A level where 1 to 10 white spots are present on each of 10 A3 sheets.

  X: A level where 11 or more white spots are present on each of 10 A3 sheets.

  As a result, it was found that the two-component electrophotographic developer was at a level without white spots on 10 sheets of A3 paper. The evaluation results are shown in Table 1.

(2) Image gradation:
Using the 40 sheet machine as an evaluation machine, the image gradation level on the image relating to the two-component electrophotographic developer A was evaluated in the following four stages.

  A: The test image is reproduced very well.

  ○: The test image is almost reproduced.

  X: The test image is not reproduced at all.

  As a result, it has been found that the two-component electrophotographic developer reproduces the image gradation on the image very well. The evaluation results are shown in Table 1.

(Example 2)
A carrier core material for a regenerated carrier according to Example 2 was obtained in the same manner as in Example 1, except that the temperature at which heat treatment was performed was 1100 ° C. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer B according to Example 2 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that there was no white spot on 10 A3 sheets. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was reproduced very well. The evaluation results are shown in Table 1.

(Example 3)
A carrier core material for a regenerated carrier according to Example 3 was obtained in the same manner as in Example 1 except that the temperature at which the heat treatment was performed was 1150 ° C. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer C according to Example 3 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that there was no white spot on 10 A3 sheets. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was reproduced very well. The evaluation results are shown in Table 1.

Example 4
A carrier core material for a regenerated carrier according to Example 4 was obtained in the same manner as in Example 1, except that the temperature at which heat treatment was performed was 1200 ° C. Table 1 shows the magnetic properties and electrical properties of the obtained regenerated carrier core material.

  Further, a two-component electrophotographic developer D according to Example 4 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 1 to 10 white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was reproduced very well. The evaluation results are shown in Table 1.

(Example 5)
A carrier core material for a regenerated carrier according to Example 5 was obtained in the same manner as in Example 3 except that the oxygen concentration at the time of heat treatment was 5000 ppm. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer E according to Example 5 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 1 to 10 white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was reproduced very well. The evaluation results are shown in Table 1.

(Example 6)
A carrier core material for a regenerated carrier according to Example 6 was obtained in the same manner as in Example 3, except that the oxygen concentration at the time of heat treatment was 10,000 ppm. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer F according to Example 6 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that there was no white spot on 10 A3 sheets. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was almost reproduced. The evaluation results are shown in Table 1.

(Example 7)
Silicone resin in which two types of silicone resins (Toray Dow Corning: SH-804, Toray Dow Corning: SR-2402) are mixed as a coating resin in a ratio of SH-804: SR-2402 = 6: 4 And a carrier core material for a regenerated carrier according to Example 7 was obtained in the same manner as in Example 3, except that no alumina was added. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer G according to Example 7 was produced in the same manner as in Example 1, and the carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that there was no white spot on 10 A3 sheets. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was reproduced very well. The evaluation results are shown in Table 1.

(Example 8)
A carrier core material for a regenerated carrier according to Example 8 was obtained in the same manner as in Example 7 except that the carrier core material composition was Mn—Mg—Fe ferrite. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer H according to Example 8 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that there was no white spot on 10 A3 sheets. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was almost reproduced. The evaluation results are shown in Table 1.

(Comparative Example 1)
A carrier core material for a regenerated carrier according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the temperature for performing the heat treatment was 600 ° C. and the atmosphere for the heat treatment was air. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer I according to Comparative Example 1 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 11 or more white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Comparative Example 2)
A carrier core material for a regenerated carrier according to Comparative Example 2 was obtained in the same manner as in Example 1, except that the temperature at which the heat treatment was performed was 600 ° C. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer J according to Comparative Example 2 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 1 to 10 white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Comparative Example 3)
A carrier core material for a regenerated carrier according to Comparative Example 3 was obtained in the same manner as in Example 1 except that the temperature at which heat treatment was performed was 700 ° C. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer K according to Comparative Example 3 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 1 to 10 white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Comparative Example 4)
A carrier core material for a regenerated carrier according to Comparative Example 4 was obtained in the same manner as in Example 1 except that the temperature at which the heat treatment was performed was 800 ° C. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer L according to Comparative Example 4 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 1 to 10 white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Comparative Example 5)
A carrier core material for a regenerated carrier according to Comparative Example 5 was obtained in the same manner as in Example 1 except that the temperature at which the heat treatment was performed was 900 ° C. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer M according to Comparative Example 5 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 1 to 10 white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Comparative Example 6)
A recycled carrier carrier core material according to Comparative Example 6 was obtained in the same manner as in Example 3 except that the oxygen concentration during heat treatment was changed to 50000 ppm. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer N according to Comparative Example 6 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 11 or more white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Comparative Example 7)
A recycled carrier carrier core material according to Comparative Example 7 was obtained in the same manner as in Example 3 except that the oxygen concentration during heat treatment was changed to 100,000 ppm. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer O according to Comparative Example 7 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 11 or more white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Comparative Example 8)
A carrier core material for a regenerated carrier according to Comparative Example 8 was obtained in the same manner as in Example 7 except that the temperature for performing the heat treatment was 500 ° C. and the atmosphere for the heat treatment was air. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer P according to Comparative Example 8 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 11 or more white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Comparative Example 9)
A carrier core material for a regenerated carrier according to Comparative Example 9 was obtained in the same manner as in Example 7 except that the comparative example 8 was used and the temperature for the heat treatment was 600 ° C. Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the obtained regenerated carrier.

  Further, a two-component electrophotographic developer Q according to Comparative Example 9 was produced in the same manner as in Example 1, and carrier adhesion and image gradation were evaluated in the same manner as in Example 1.

(1) Evaluation of carrier adhesion:
It was found that each of the 10 sheets of A3 paper had a level of 11 or more white spots. The evaluation results are shown in Table 1.

(2) Image gradation:
It was found that the image gradation on the image was not reproduced at all. The evaluation results are shown in Table 1.

(Reference Example 1)
Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of the unused carrier before coating the resin with Mn-Fe ferrite as the carrier core material.

(Reference Example 2)
The magnetic properties of the carrier core material of the unused carrier before coating with the resin, in which the Mn-Fe ferrite of Reference Example 1 is used as a carrier core material and heat treatment is performed at a low temperature in an air atmosphere for the purpose of resistance adjustment. Table 1 shows the mechanical characteristics and electrical characteristics.

(Reference Example 3)
Table 1 shows the magnetic characteristics and electrical characteristics of the carrier core material of an unused carrier before coating the resin with Mn—Mg—Fe ferrite as the carrier core material.

The measurement of the resistance value indicating the electrical characteristics will be described. First, two brass plates each having a thickness of 2 mm and having an electropolished surface as electrodes on an insulating plate placed horizontally, for example, an acrylic plate coated with Teflon (registered trademark), have an interelectrode distance of 2 mm. Arrange as follows. At this time, the normal direction of the two electrode plates is set to the horizontal direction. After inserting 200 ± 1 mg of the powder to be measured into the gap between the two electrode plates, a magnet having a cross-sectional area of 240 mm ² is arranged behind each electrode plate to form a bridge of the powder to be measured between the electrodes. . In this state, each voltage is applied between the electrodes in order from a small one, and a current value flowing through the powder to be measured is measured by a two-terminal method to calculate an electric resistance value. Here, a super insulation meter SM-8215 manufactured by Hioki Electric Co., Ltd. is used. And the resistance value ((ohm)) at the time of the application at the time of applying each voltage in a table | surface was measured. The applied voltage was 100V.

Moreover, about the measurement of the magnetization which shows a magnetic characteristic, the magnetic susceptibility was measured using VSM (Toei Kogyo Co., Ltd. make, VSM-P7). Here, in Table 1, “σs” is saturation magnetization, and “σ ₁₀₀₀ ” is magnetization in the case of an external magnetic field 1000 Oe.

  Moreover, in order to measure the residual amount of organic substance about the carrier component which heat-processed, the carbon content was measured. The carbon amount was measured by an infrared absorption method (integration method) based on JIS G 1211 “Method for quantifying carbon in iron and steel”. Specifically, about 1 g of a sample and 1 g of tungsten as a combustion aid are weighed in a crucible, heated to a high temperature in an oxygen stream, sufficiently heated to carbon dioxide, and this is infrared together with oxygen. It sent to the absorption cell and carbon content was quantified from the infrared absorption amount.

  In Table 1, “alumina-containing silicone resin” refers to a resin in which alumina is contained in a silicone resin as a coating resin, and “alumina-free silicone resin as a coating resin” refers to an alumina in a silicone resin. The thing which is not contained is shown.

With reference to Table 1, first, the case where the core composition of the carrier core material is Mn—Fe ferrite will be examined. Examining the magnetic characteristics, Reference Examples 1 and 2 show the actual use width, and the value of σ ₁₀₀₀ is 67.2 to 69.6 Am ² / kg. There is no level. Also in Examples 1 to 7, the value of σ ₁₀₀₀ is at least 67.7 Am ² / kg, which is a level that does not cause a problem in the actual use situation. On the other hand, looking at Comparative Example 1, the value of σ ₁₀₀₀ is 37.9 Am ² / kg. Further, in Comparative Example 6 is also a 51.3Am ² / kg, Comparative Example 7 is also a 36.2Am ² / kg. Such a low magnetization is a problematic level in actual use. This is because the magnetization of the carrier core material greatly decreases when the oxygen concentration is high during heat treatment.

  Examining the electrical characteristics, the values of Reference Examples 1 and 2 are 2.3E + 06 to 7.3E + 07Ω in the case of 100V. In the case of Examples 1 to 7, the maximum value is 3.0E + 07Ω. On the other hand, in Comparative Examples 1-9, the value is at least 1.3E + 09Ω. Such a high resistance value is a problematic level in actual use situations.

  This electrical characteristic is supported by the carbon content. That is, about Examples 1-7, it is 0.006 weight% at the maximum as carbon content of a carrier core material. This is probably because the organic substance such as resin is almost completely removed in the heat treatment step described above, so that the resistance value is relatively low. On the other hand, about Comparative Examples 2-5, it contains 0.012 weight% at least as carbon amount of a carrier core material. That is, it is considered that the coating resin and spent cannot be completely removed, and the resistance value is increased by the influence of the remaining organic component. Incidentally, for Comparative Example 1, Comparative Example 6 and Comparative Example 7, the carbon amounts were 0.004% by weight, 0.005% by weight and 0.004% by weight, respectively, and from these carbon content data, It can be understood that almost no organic component remains. In Comparative Example 1, Comparative Example 6, and Comparative Example 7, since heat treatment is performed in an atmosphere having a high oxygen concentration as described above, magnetization is reduced, and from the viewpoint of carrier adhesion and image gradation, This is a problem level in actual use situations. In addition, it can be understood that a considerable amount of carbon remains in Comparative Examples 8 and 9.

  FIG. 6 is an electron micrograph showing the appearance of the carrier core material 15 in Comparative Example 8. FIG. 7 is an electron micrograph showing the appearance of the carrier core material 16 in Comparative Example 9. 6 and 7 and FIGS. 1 and 4 again, the appearance of the carrier core shown in FIGS. 6 and 7 and the appearance of the carrier core shown in FIGS. It is very different. This is considered that in the case of the carrier core shown in FIGS. 6 and 7, a large amount of carbonized carbide remains on the surface. As described above, this is supported by the carbon content data in Comparative Examples 8 and 9 in Table 1.

  It can be seen that the Mn—Mg—Fe based ferrite shown in Example 8 also exhibits the same electrical and magnetic characteristics as the Mn—Mg—Fe based ferrite shown in Reference Example 3. That is, even in such a composition of the core core material, the electrical characteristics and magnetic characteristics as the carrier core material can be prevented from being deteriorated.

  As described above, the method for manufacturing a regenerative carrier and the regenerative carrier according to the present invention can be manufactured at a low cost without deteriorating the electrical characteristics and magnetic characteristics as compared with a new product.

In the above embodiment, N ₂ gas is used as the inert gas. However, the present invention is not limited to this, and other inert gases such as Ar (argon) gas and He (helium) gas are used. It may be used.

  Further, in the method for producing a regenerated carrier according to the present invention, the used developer that has been used for a predetermined period is used. However, the developer is not limited to this, and has not reached the end of its life and has been used as a developer even once. Things can also be used. In addition, when manufacturing a new carrier, defective products generated in the resin coating process on the carrier core material, specifically, the resin coating is too thick or too thin in the resin coating process, or evenly on the surface. A coating carrier that cannot be coated or has uneven coating can be regenerated using the same method.

  Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  A method for producing a regenerated carrier, a regenerated carrier, a carrier core material of a regenerated carrier, an electrophotographic developer, and a method for producing an electrophotographic developer according to the present invention are applied to a copying machine or the like that requires ecology. It is used effectively.

  11, 13, 15, 16 Carrier core material, 12, 14 carrier.

Claims (3)

General formula: M _x Fe _3-x O ₄ (0 ≦ x ≦ 1, where M is at least one metal selected from the group consisting of Mg, Mn, Ca, Ti, Cu, Zn, Sr, Ni) Is a regenerated carrier manufacturing method in which a reusable carrier is regenerated from a coating carrier whose surface is coated with a resin and a developer composed of toner. And
Separating the carrier component from the developer;
A heat treatment step of heat-treating the separated carrier component in a temperature range of 1000 ° C. to 1250 ° C. in an inert gas atmosphere;
After the heat treatment step, seen containing a resin coating step of coating a resin on the surface of the obtained carrier core material component,
In the heat treatment step, the carrier component is heat-treated in an inert gas atmosphere having an oxygen concentration of 10,000 ppm or less,
The method for producing a regenerated carrier, wherein the heat treatment performed in the method for producing a regenerated carrier is once . The inert gas includes N ₂ gas, the manufacturing method of the reproduced carrier of claim 1. The developer is of the predetermined time period used is spent as an electrophotographic developer, method for producing a reproduced carrier according to claim 1 or 2.