JP2007047341A - Method for regenerating carrier for two-component electrostatic charge image dry developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for regenerating a carrier for a two-component electrostatic charge image dry developer, by which spent toner on the carrier surface and resin coating the carrier surface can be completely removed and the initial characteristics can easily be recovered. <P>SOLUTION: The method for regenerating a carrier for a two-component electrostatic charge image dry developer aims to regenerate the carrier having resin coated on the surface of a core material, and is characterized in that a used two-component developer or a resin coated carrier obtained by separating a toner component by a toner removing process on the used developer is subjected to carbonization and then to decarbonization followed by characteristic processing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for reproducing a carrier for a two-component electrostatic charge image dry developer in an electrophotographic system used for a copying machine, a printer, and the like, and in particular, a two-component electrostatic charge in which the surface of a core material is coated with a resin. The present invention relates to a method for reproducing a carrier for an image dry developer.

  The two-component electrostatic charge image dry developer in the electrophotographic system is composed of a toner and a carrier, and the carrier is mixed and agitated with the toner in the developing tank to give the toner a desired charge and charge the toner. It is a carrier material that is carried from the magnet roll to the electrostatic latent image on the photoreceptor to form a toner image. The toner transferred to the photoconductor is copied on a sheet as an image through steps of transfer and fixing. On the other hand, even after the toner image is formed, the carrier remains on the magnet roll by being held by the magnet, returns to the developing tank again, is again mixed and stirred with newly supplied toner, and is repeatedly used. The Therefore, in order to stably maintain desired image quality during repeated copying, it is required that the characteristics of the carrier be stable during the period of use.

  In recent years, many of the two-component electrostatic charge image dry developer carriers are repeatedly copied over tens of thousands of sheets, and in order to stably obtain higher quality images, the carrier surface is coated with a resin. ing.

However, since the developer is constantly subjected to stress such as collision between particles or collision with a member such as a developing tank and a photoreceptor during repeated use, the toner component is fused to the carrier surface due to heat generation, or the toner. This causes a so-called spent in which an external additive such as TiO ₂ or SiO ₂ contained in is buried in the carrier surface. When this spent occurs, it is hindered by the toner fused to the carrier or the buried external additive, and an appropriate charge cannot be imparted to the toner. As a result, fogging, toner scattering, and gradation deterioration are caused. Such as image defects.

  At the same time, so-called coat peeling occurs in which the resin coated on the carrier surface peels due to the stress as described above. When this coat peeling occurs, the electrical resistance of the carrier is lowered, causing deterioration of fine line reproducibility and image defects due to carrier adhesion. In addition, an appropriate charge cannot be imparted to the toner, and as a result, fogging due to a decrease in charge amount, image defects such as toner scattering and gradation deterioration, or insufficient image density or carrier scattering due to an increase in charge amount. This also causes image defects such as.

  As described above, since the carrier characteristics deteriorate with use time in repeated copying using a copying machine, a printer, or the like, the developer itself needs to be replaced with a new one.

  In order to prevent such deterioration of the carrier characteristics, the type of resin to be coated on the carrier surface has been studied conventionally, but at present, prevention of spent and coat peeling is still insufficient.

  Conventionally, the developer that has been exchanged and recovered due to the deterioration of the carrier characteristics as described above has been discarded. However, in recent years, environmental pollution due to industrial waste has been regarded as a problem, and reuse of the recovered developer is one of the issues. It has become.

  Regarding the reuse of the collected developer, especially the carrier, for example, Patent Document 1 (JP-A-3-89254), Patent Document 2 (JP-A-6-149132) and Patent Document 3 (JP-A-7-28280). However, in each of these patent documents, the purpose is only to remove the toner component spent on the carrier surface, not to remove the coating resin. Also, the carrier surface remains coated with the resin. As described above, since the resin coated on the surface of the carrier by repeated copying has not a little spent or coat peeling, the invention disclosed in each of these patent documents has stable carrier characteristics after reproduction. Therefore, various characteristics such as initial electrical resistance and chargeability may not be regenerated, or the carrier life may be shortened when reused.

  Patent Document 4 (Japanese Patent Laid-Open No. 47-12286) proposes a method of heating and regenerating the recovered carrier at a high temperature of at least about 1000 ° F. (about 540 ° C.). Although a specific type of coating resin can be removed, carrier characteristics such as electric resistance and saturation magnetization are deteriorated by high-temperature heat treatment.

  Further, in Patent Document 5 (Japanese Patent No. 2649344), Patent Document 6 (Japanese Patent Laid-Open No. 7-72665) or Patent Document 7 (Japanese Patent Laid-Open No. 2000-231224), two steps are required to solve the above-mentioned problem. It is proposed to perform the heat treatment. That is, the purpose is to remove the coating resin in the first heat treatment, and the purpose is to restore the properties of the ferrite carrier to the original state by adjusting the firing temperature or firing atmosphere in the second heat treatment. It is said.

  However, in the above-described method, in the first heat treatment, thermal runaway of the processing apparatus is likely to occur due to adhesion of the coating resin on the carrier surface to the inner wall of the processing apparatus due to thermal melting or accumulation of combustion heat of the coating resin, and supply stability. From the viewpoint of controlling the firing temperature and the like, it has been difficult to achieve the objectives of manufacturing.

  At the same time, in the first heat treatment, the removal of the coating resin is not complete, and depending on the concentration of the toner in the collected developer, there is a large variation in characteristics between the treated carrier particles. It was. For this reason, in order to suppress the phenomenon, a pretreatment for removing the toner has to be performed in order to reduce the concentration of the toner in the collected developer as much as possible.

  In addition, since the coating resin component remaining in the first heat treatment functions as a reducing agent in the second heat treatment, it is difficult to control the firing atmosphere, and carrier characteristics such as electric resistance and saturation magnetization Cannot be restored to the original level, causing deterioration of image characteristics or carrier scattering.

  Furthermore, the coating resin component remains in the finally obtained regenerated carrier, and removal of the coating resin on the carrier surface, which is the original purpose, may not be achieved. As a result, when the surface of the core material is newly coated with the resin again, the remaining coating resin component inhibits the adhesion between the core material surface and the new coating resin. It causes peeling.

JP-A-3-89254 Japanese Patent Laid-Open No. 6-149132 JP-A-7-28280 JP-A-47-12286 Japanese Patent No. 2649344 JP 7-72665 A Japanese Patent Laid-Open No. 2000-231224

  Accordingly, it is an object of the present invention to completely remove the spent toner on the carrier surface and the resin coated on the carrier surface to easily restore the initial characteristics and obtain desired characteristics. It is an object of the present invention to provide a method for regenerating a carrier for a component electrostatic charge image dry developer.

  The present inventors have made extensive studies to solve the above-described problems of the prior art, and have been used and recovered as a two-component electrostatic image dry developer or a resin coating from which the toner component has been removed from the developer. It has been found that the above object can be achieved by subjecting the carrier to carbonization treatment, followed by decarburization treatment and property adjustment treatment.

  That is, the present invention is a method for regenerating a carrier in which the surface of a core is coated with a resin, wherein the used two-component developer is carbonized, decarburized, and then subjected to characteristic processing. A two-component electrostatic charge image dry developer carrier regeneration method is provided.

  The present invention also relates to a method for regenerating a carrier in which the surface of a core material is resin-coated, and the resin-coated carrier obtained by separating toner components from a used two-component developer by detoning treatment is carbonized. Then, a method for regenerating a carrier for a two-component electrostatic charge image dry developer, characterized by performing a decarburization process and then a characteristic process.

  In the carrier regeneration method according to the present invention, the carbonization treatment is preferably performed in an oxygen-free atmosphere at 500 to 800 ° C.

  In the carrier regeneration method according to the present invention, it is preferable that the decarburization treatment is performed in a combustion atmosphere of 600 to 900 ° C.

  In the carrier regeneration method according to the present invention, it is desirable that the characteristic adjustment process is performed at an oxygen concentration of 1100 ° C. to 1300 ° C. and 0 to 5% by volume.

  In the carrier regeneration method according to the present invention, it is preferable that the amount of residual carbon before the property adjustment treatment is 0.1% by weight or less.

  In the carrier recycling method according to the present invention, a heatable cylindrical body having a screw therein is arranged in two upper and lower stages, and further using a device having a cooling unit, the carbonization treatment is performed at the upper cylindrical body part. It is desirable that the decarburization process is continuously performed in the lower cylindrical portion.

  The two-component electrostatic charge image dry developer carrier regeneration method according to the present invention can not only completely remove the spent toner on the carrier surface and the resin coated on the carrier surface, but also the initial characteristics of the carrier. Can be easily recovered.

  Hereinafter, an embodiment of a method for regenerating a carrier for a two-component electrostatic charge image dry developer according to the present invention will be described.

  In the carrier regeneration method according to the present invention, the used two-component developer, or the resin-coated carrier obtained by separating the toner component from the used two-component developer by detoning treatment is carbonized, respectively. A decarburization process is performed, and then a characteristic process is performed.

  Here, a toner removal method for separating a toner component such as a toner and an external additive from a two-component developer to obtain a resin-coated carrier is a method of first using repeatedly collected and recovered two-component developer. This is a method of separating toner components by wind force such as blow-off, wind sieve, airflow classifier, etc., a method of separating toner components by washing with water, organic solvent, etc., or a combination of these methods. The toner components such as the toner adhering to the toner or the external additive used as a fluidizing agent in the toner are separated.

  At this time, in the method using wind power, the air volume is such that carrier particles are not removed from the developer to be processed. In addition, the collected developer may contain a large-particle-size toner lump that can be seen with the naked eye, and may not be removed by a method using wind power. In this case, it can be removed with a sieve screen such as a vibrating sieve or a gyro shifter. In the method of washing with an organic solvent, it is preferable to select an organic solvent in which the toner is soluble. In this way, the collected used two-component developer is separated into a resin-coated carrier and a toner component.

  However, in the present invention, a toner component such as a toner having a strong removal effect in the carbonization treatment and decarburization treatment and electrostatically adhering to the carrier or an external additive used as a fluidizing agent in the toner. Therefore, the toner removal process can be omitted. That is, as described above, the used two-component developer may be carbonized as it is, then decarburized, and then subjected to characteristic processing.

  Next, the used two-component developer or the resin-coated carrier obtained as described above is carbonized.

  The purpose of carbonization is to carbonize the spent toner and the coated coating resin layer on the carrier surface, and the heating temperature and residence time are appropriately selected according to the thermal characteristics and coating amount of the spent toner and coating resin. The If the heating temperature is low, carbonization of the spent toner and the coated coating resin layer tends to be insufficient, and in the next decarburization treatment, thermal runaway of the processing device due to combustion of the remaining spent toner and coating resin is likely to occur. In terms of supply stability and firing temperature control, it may be difficult to achieve the intended purpose of manufacturing. If it is less than 500 degreeC, carbonization will not fully advance. Therefore, the treatment is preferably performed at a heating temperature of 500 to 800 ° C. for a residence time of 15 minutes to 2 hours, more preferably at a heating temperature of 600 to 700 ° C.

  The carbonization is preferably performed in an oxygen-free atmosphere. When heated in the presence of oxygen, the spent toner and coating resin do not carbonize and become a normal combustion reaction, and heat of the processing device due to combustion of the spent toner and coating resin. Runaway is likely to occur, and it may be difficult to achieve the objective of manufacturing from the viewpoint of supply stability, firing temperature control, and the like.

  As the apparatus used for the carbonization treatment, a known heat treatment apparatus can be used as long as it can realize the atmosphere, heating temperature and residence time. For example, rotary kiln type, screw type, tunnel-trolley type, fluidized bed A die type, a shuffling type or a peristaltic type can be mentioned, but a screw type heat treatment furnace is preferable for carbonization from the viewpoint of control of productivity or carrier characteristics.

  Next, a decarburization process is performed on the spent toner obtained by the carbonization process and the carrier on which the resin coating layer is carbonized. The spent toner carbonized by the carbonization treatment and the coating resin are decarburized in a combustion atmosphere, so-called smokeless combustion, and removed as carbon dioxide. By performing this carbonization treatment and decarburization treatment in combination, the characteristic adjustment process in the next step can be stably performed, and finally, the regenerated carrier characteristics can be stabilized.

  Conversely, if a large amount of spent toner and coating resin remain after the carbonization and decarburization processes, that is, before the characteristic adjustment process, the carrier (core material) is regenerated through the characteristic adjustment process. However, the characteristics of the carrier coated again may not be stable, and various characteristics such as initial electrical resistance and chargeability may not be regenerated, or the carrier lifetime may be reduced when reused. It may become shorter. Not only that, but in the property adjustment process, the remaining spent toner and coating resin act as a reducing agent, making it difficult to control the firing atmosphere and returning carrier properties such as electrical resistance and saturation magnetization to their original levels. May not be possible. Therefore, it is desirable that the carbon content of the carrier (core material) from which the toner component, coating resin, and the like after the decarburization treatment are removed is 0.1% by weight or less.

  In order to sufficiently exhibit the decarburization effect and reduce the residual carbon amount as much as possible, the atmosphere during the decarburization treatment is preferably a combustion atmosphere. Moreover, it is preferable to process at 600-900 degreeC for 15 minutes-2 hours, and it is more preferable to process at the heating temperature of 700-800 degreeC. When the temperature is lower than 600 ° C., the spent toner and the coating resin carbonized by the carbonization treatment are not sufficiently combined with oxygen and remain in a large amount. When the treatment is performed at a temperature exceeding 900 ° C., a hematite layer is likely to be precipitated due to surface oxidation, and this tends to cause a decrease in saturation magnetization, an increase in electrical resistance, or generation of nonmagnetic particles.

  As the apparatus used for the decarburization process, a known heat treatment apparatus similar to the carbonization process can be used, and a screw-type heat treatment furnace is preferable also in the decarburization process from the viewpoint of control of productivity or carrier characteristics.

  The apparatus used for the carbonization and decarburization is preferably as shown below. In other words, this apparatus is provided with a cylindrical body having a screw inside and stacked in two upper and lower stages, and further equipped with a cooling device. In the upper cylindrical part, the inside is made oxygen-free and carbonized, and in the lower cylindrical part, the inside is made into a combustion atmosphere by supplying air and decarburized.

  The upper cylindrical body is provided with a supply device at one end, and the other end is connected to the lower cylindrical body by a communication path. A carbonization (dry distillation) gas exhaust port for discharging carbonization (dry distillation) gas is provided in the upper part near the center. In order to prevent air contamination as much as possible, the supply device adopts a screw feeder method, and separates toner components from used two-component developer or used two-component developer by detoning process. It is desirable to supply the obtained resin-coated carrier while being closely packed, and it is more preferable to introduce nitrogen gas. In order to distinguish the atmosphere of the upper cylindrical portion and the lower cylindrical portion in the communication path, it is desirable to provide a double damper.

  The lower cylinder is provided with a device for supplying air in the flow direction of the processed material from the communication path side connected to the upper cylinder, and the other end is decarburized at the lower part. A discharge port for discharging the object and a combustion gas exhaust port for discharging the combustion gas are provided at the top. The combustion state inside the lower cylindrical body is controlled by the air supply device.

  In order to cool the discharged processed material, a cooling device is connected to the discharge port of the lower cylindrical body so that it can be continuously processed.

  The method of heating the upper and lower two-stage cylinders is preferably an external heating type using propane as fuel, but the carbonization (dry distillation) gas discharged from the carbonization (dry distillation) gas exhaust port of the upper stage cylinder is combusted air through the exhaust duct. It is more preferable that the combustion energy is obtained by suctioning with the supply flow of the gas, mixing with the combustion air, and burning in the hot air generator.

  Furthermore, the characteristic adjustment process is performed for the purpose of adjusting the characteristic of the carrier from which the toner and coating resin that have been spent in the decarburization process are almost removed. Thereby, the characteristic deterioration of the carrier which has arisen by the carbonization process or the decarburization process can be returned to a normal state.

  The characteristic adjustment process is performed in an atmosphere in which the oxygen concentration is controlled, and is preferably performed at an oxygen concentration of 0 to 5% by volume. The heating temperature and the residence time are usually 1100 to 1300 ° C. for 1 to 5 hours, preferably about 3 hours. When the oxygen concentration exceeds 5% by volume or the heating temperature is less than 1100 ° C., the recovery of defects such as the deterioration of the magnetic properties of the carriers and the generation of low-magnetized particles is not sufficient, and they are regenerated and reused. At this time, image defects such as carrier adhesion are caused. On the other hand, when the heating temperature exceeds 1300 ° C., the carrier particles are melted and the particle shape cannot be maintained.

  As the apparatus used for the characteristic adjustment treatment, a known heat treatment apparatus can be used as long as it can realize the oxygen atmosphere, heating temperature and residence time, for example, rotary kiln type, screw type, tunnel-trolley type, A fluidized bed type, a shuffling type, or a peristaltic type may be mentioned. A tunnel-trolley type electric furnace is preferable because stable atmosphere control can be easily realized.

  In this way, the carrier from which the spent toner and the coating resin are removed is regenerated to the same level as the carrier (core material) newly made from the raw material, and the carbon caused by the remaining spent toner or coating resin. The remaining amount is extremely small.

  As a carrier constituting a used developer applicable to the carrier regeneration method according to the present invention, all two-component electrostatic charge image dry developer carriers, including those already known, are targeted, and an iron powder carrier , Magnetite carriers and ferrite carriers using Cu, Zn, Mg, Mn, Ca, Li, Sr, Sn, Ni, Al, Ba, Co, Bi, Zr, etc. Preferably, a Mn—Mg ferrite carrier is particularly preferred.

  Moreover, there is no restriction | limiting in characteristics, such as a shape of the said carrier, surface property, a particle size, a magnetic characteristic, resistance value, and charging property.

  The resin coated on the surface of the carrier constituting the used developer that can be applied to the carrier recycling method according to the present invention is not particularly limited, and various conventionally known resins can be mentioned. For example, amino-type resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, and polyamide resin may be mentioned. Furthermore, polyvinyl and polyvinylidene resins, acrylic resin, polymethyl methacrylate resin, polyacrylonitrile resin, polyvinyl acetate Resin, polyvinyl acetate resin, polyvinyl alcohol resin, polyvinyl butyral resin, cellulose resin such as ethyl cellulose resin, polystyrene resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoro Propylene resin, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, terpolymer of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomer Fluoro terpolymers such Rimmer, a silicone resin or an acrylic resin, polyester resin, epoxy resin, alkyd resin, urethane resin, modified silicone resin modified with fluorine resin or the like, and mixtures of these resins.

  The resin coating layer includes a nigrosine dye, a triphenylmethane dye, a quaternary ammonium salt, a resin containing a quaternary ammonium group and / or an amino group, a trimethylethane dye, a metal complex of salicylic acid, and a metal of benzyl acid. Complex salts, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex salt azo dyes, heavy metal-containing acid dyes such as azochrome complexes, calixarene type phenolic condensates, cyclic polysaccharides, carboxyl groups and / or sulfonyl groups The thing containing charge control materials, such as resin to contain, is included.

  The resin coating layer includes those containing a conductive material such as metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide.

  The toner constituting the used developer applicable to the carrier recycling method according to the present invention includes pulverized toner particles produced by a pulverization method and polymerized toner particles produced by a polymerization method. In the present invention, the toner particles obtained by any method are also used.

  The binder resin constituting the toner particles, the charge control agent, the colorant (coloring material), and the external additive for improving fluidity are not particularly limited, and the average particle size of the toner particles is also particularly limited. Is not to be done.

  The carrier regenerated by the present invention may be used as it is, and it is used as a core material, and the core resin surface is again coated with the coating resin, the charge control material and the conductive material as described above. May be.

  The carrier regenerated according to the present invention can be made into a carrier having the completely different characteristics from those before the regeneration by performing the resin coating treatment.

  EXAMPLES The present invention will be specifically described below based on examples and the like, but the present invention is not limited to these examples.

[Reference Example 1]
A thermoplastic acrylic resin (trade name: Dyana) is prepared by using toluene as a solvent on the surface of 100 parts by weight of an unreproduced Mn-Mg-Sr ferrite core material (core material A) having an average particle diameter of 35 μm and made from raw materials. 1.5 parts by weight of Le BR-52 (manufactured by Mitsubishi Rayon Co., Ltd.) was coated using a uniaxial indirect heating dryer to obtain a resin-coated carrier A.

The saturation magnetization of the core material A was 70 emu / g (A · m ² / kg) as measured by a direct current magnetization characteristic recording device BHU-60 manufactured by Riken Denshi. Moreover, it was less than 0.01 weight% when the carbon content (residual amount) of the core material was measured with the carbon analyzer C-200 made from LECO. Further, using a developing device of a commercially available copying machine, the core material A filled with 1000 g of the core material A, the core material holding the core material A was rotated at a peripheral speed of 300 mm / s for 5 minutes, and scattered core material particles. It was 1.50 mg when the quantity (scattering quantity) of was measured. The amount of scattering represents the amount of low-magnetization particles contained in the core material and affects carrier scattering in repeated copying. The amount of scattering is desirably 3.00 mg or less. These measurement results are shown in Table 1.

  Using a commercially available TOSHIBA TEC copier FANTASIA 200, 30,000 copies of the developer A produced by mixing 93 parts of the resin-coated carrier and 7 parts of the toner were repeatedly tested to measure the amount of charge as a developer evaluation. Image evaluation such as image density, carrier scattering, and toner scattering was performed, and the initial value was compared with that after 30,000 sheets. Developer A had an appropriate charge amount both at the initial stage and after 30,000 sheets, and no problem was found in image evaluation. The results are shown in Table 2.

  Further, in order to obtain the peeling rate of the resin coated on the resin-coated carrier A, the toner is removed by airflow classification from the developer A that has been deteriorated through repeated copying tests, and only the deteriorated carrier A is used. After washing, the carbon content was measured in the same manner as described above. As a result, it was 0.92% by weight, and the peel rate (comparison with that before the repeated copy test) was 25% as shown in Table 2.

  The toner was removed from the used developer A of Reference Example 1 with an air classifier to separate the toner components, and a used resin-coated carrier A was obtained.

  The used resin-coated carrier A was continuously subjected to carbonization treatment at 600 ° C. in an oxygen-free atmosphere and decarburization treatment at 700 ° C. in a combustion atmosphere using a screw-type heating furnace. Furthermore, using a tunnel-trolley type electric furnace, a characteristic adjustment treatment was performed at an oxygen concentration of 3 vol% and 1200 ° C. to obtain a core material B. Thereafter, the resin was coated in the same manner as in Reference Example 1 to obtain a resin-coated carrier B. Further, a developer B was obtained in the same manner as in Reference Example 1, and 30,000 copies were repeatedly tested.

  A core material C was obtained in the same manner as in Example 1 except that the used developer A before separating the toner component of Reference Example 1 was used instead of the used resin-coated carrier A. Thereafter, the resin was coated in the same manner as in Reference Example 1 to obtain a resin-coated carrier C. Further, developer C was obtained in the same manner as in Reference Example 1, and 30,000 copies were repeatedly tested.

  A core material D was obtained in the same manner as in Example 2 except that the carbonization temperature was 500 ° C., the decarburization treatment was 600 ° C., and the treatment conditions for the characteristic adjustment treatment were oxygen concentration 0 volume% and 1100 ° C. . Thereafter, the resin was coated in the same manner as in Reference Example 1 to obtain a resin-coated carrier D. Further, developer D was obtained in the same manner as in Reference Example 1, and 30,000 copies were repeatedly tested.

  A core material E was obtained in the same manner as in Example 1 except that the carbonization temperature was 800 ° C., the decarburization treatment was 900 ° C., and the characteristic adjustment treatment conditions were oxygen concentration 5% and 1300 ° C. Thereafter, the resin was coated in the same manner as in Reference Example 1 to obtain a resin-coated carrier E. Further, developer E was obtained in the same manner as in Reference Example 1, and 30,000 copies were repeatedly tested.

Comparative example

[Comparative Example 1]
The used developer A before separating the toner component of Reference Example 1 was used, and this was subjected to a heat treatment in a combustion atmosphere at 700 ° C. in a rotary kiln furnace, whereby a core material F was obtained. Thereafter, the resin was coated in the same manner as in Reference Example 1 to obtain a resin-coated carrier F. Further, the developer F was obtained in the same manner as in Reference Example 1, and 30,000 copies were repeatedly tested.

[Comparative Example 2]
The toner was removed from the used developer A of Reference Example 1 with an air classifier to separate the toner components, and a used resin-coated carrier A was obtained.

  This used carrier A was subjected to heat treatment at 550 ° C. in a combustion atmosphere using a screw-type heating furnace, and further using a tunnel-trolley type electric furnace, with an oxygen concentration of 3% by volume and 1200 ° C. The core material G was obtained by heat treatment. Thereafter, the resin was coated in the same manner as in Reference Example 1 to obtain a resin-coated carrier G. Further, a developer G was obtained in the same manner as in Reference Example 1, and 30,000 copies were repeatedly copied.

  Table 1 shows the properties (carbon content, saturation magnetization, and scattering amount) of the core materials of Examples 1 to 4 and Comparative Examples 1 to 2 together with the conditions of the regeneration process. Table 2 shows the characteristics of the developer (results of repeated copying test and peeling rate of 30,000 sheets) together with the conditions of the regeneration processing step. The properties of the core material and the developer were evaluated in accordance with the method described in Reference Example 1 described above.

  As a result, although the screw type heating furnace which performed the carbonization process and the decarburization process of Examples 1 to 4 could be operated without any problems, the rotary kiln furnace in Comparative Example 1 and the screw in Comparative Example 2 were operated. -For type heating furnaces, combustion of the coating resin component occurs, heating temperature control is unstable due to thermal runaway, adhesion occurs on the inner wall of the apparatus, and the supply of processed material cannot be performed stably. It was.

  Moreover, although operation of the tunnel-trolley type electric furnace which performed the characteristic adjustment process of Example 1-Example 4 did not have a problem, when Comparative Example 2 was performed, removal of coating resin in a screw type heating furnace Therefore, due to the gas generated from the coating resin, the variation of the actual oxygen concentration measurement value with respect to the oxygen concentration set value was large, and the oxygen concentration control was not stable.

  Further, as is apparent from Table 1, the core materials B to E of Examples 1 to 4 have the same core material characteristics as the core material A of Reference Example 1 which is an unreproduced product.

  On the other hand, the core material F of Comparative Example 1 had a large amount of residual carbon before the characteristic adjustment treatment (third heat treatment), and many coating resin components remained in the finally regenerated core material. Further, the saturation magnetization is remarkably inferior to the core A of the comparative example 1 that has not been reproduced, and the amount of scattering of the core is large. In the core material G of Comparative Example 2, as in Comparative Example 1, a large amount of residual carbon is detected in the core material before the characteristic adjustment process (third heat treatment) and finally regenerated.

  As is clear from Table 2, the developer B to the developer E of Examples 1 to 4 relate to the transition of the charge amount (comparison between the initial and 30,000 sheets) and the coating resin peeling rate after 30,000 sheets. The same characteristics as those of the developer A of Reference Example 1 using the carrier core material A which is an unreproduced product are shown. In addition, there is no problem in image evaluation in the initial stage and after 30,000 sheets.

  On the other hand, the developer F of Comparative Example 1 has an image density that is too high after the resin coating again because a large amount of the coating resin component remains in the finally regenerated core material. The result was extremely low. In addition, as can be seen from the fact that the saturation magnetization of the core material does not recover and has a remarkably low value and the amount of scattering is large, a large amount of carrier scattering occurs due to the inclusion of many low magnetization particles. . As a result, repeated copying tests had to be abandoned.

  Further, although the developer G of Comparative Example 2 had a slightly high initial charge amount, it was an acceptable level in the initial image evaluation. However, in the image evaluation after the repeated copying test of 30,000 sheets, the charge amount is remarkably reduced, toner scattering occurs, and carrier scattering is also observed. As can be seen from the fact that the coating resin peeling rate after 30,000 sheets is large, the coating resin has not been sufficiently removed by the regeneration treatment, and the core material A of Reference Example 1 which is an unregenerated core material is restored. This is probably because the adhesiveness of the newly coated resin was hindered by the failure, and it was easily peeled off.

  The carrier obtained by the method for regenerating a carrier for a two-component electrostatic charge image dry developer according to the present invention can completely remove spent toner and coated resin, and makes the carrier characteristics the initial characteristics. In addition to being able to recover, it can impart desired properties. Accordingly, the carrier obtained by the present invention is suitably used as a carrier for a two-component electrostatic charge image dry developer by coating a resin if necessary.

Claims (7)

A method for reclaiming a carrier whose surface is coated with a resin, wherein the used two-component developer is carbonized, decarburized, and then subjected to characteristic treatment. A method for regenerating a carrier for a charge image dry developer. A method for reclaiming a carrier whose surface is coated with a resin, comprising: carbonizing a resin-coated carrier obtained by separating toner components from a used two-component developer by detoning, and then decarburizing. And then subjecting it to a characteristic treatment. A method for regenerating a carrier for a two-component electrostatic charge image dry developer. The method for regenerating a carrier for a two-component electrostatic charge image dry developer according to claim 1 or 2, wherein the carbonization is performed in an oxygen-free atmosphere at 500 to 800 ° C. The method for regenerating a carrier for a two-component electrostatic charge image dry developer according to claim 1, 2 or 3, wherein the decarburization treatment is performed in a combustion atmosphere of 600 to 900 ° C. The method for regenerating a carrier for a two-component electrostatic charge image dry developer according to any one of claims 1 to 4, wherein the characteristic adjustment treatment is performed at 1100C to 1300C and an oxygen concentration of 0 to 5% by volume. The method for regenerating a carrier for a two-component electrostatic charge image dry developer according to any one of claims 1 to 5, wherein a residual carbon amount before the property adjustment treatment is 0.1 wt% or less. Heatable cylinders with screws inside are arranged in two upper and lower stages, and further using a device having a cooling part, the carbonization process is performed on the upper cylinder part and the decarburization process is performed on the lower cylinder part. The method for regenerating a carrier for a two-component electrostatic charge image dry developer according to any one of claims 1 to 6, which is carried out continuously.