JP4244197B2 - Electrophotographic carrier processing method - Google Patents

Description

  The present invention relates to a method for processing an electrophotographic carrier, and more particularly to an effective method for processing a used carrier coated with a fluorine resin.

  In recent years, awareness of environmental conservation has increased rapidly. In the fields of copiers that use electrophotography, laser printers, facsimiles, printing machines, etc., various improvements have been made to reuse recovered parts in order to meet such environmental conservation requirements. It has been. For example, in a copying machine, various devices arranged so as to surround a photoconductor can be easily attached and detached, and various devices that have undergone a certain use state are removed, After each part is collected and the function is recovered through processes such as disassembly and cleaning, it is again attached to the copying machine. In this way, recently, the cycle of reuse has been slow, leading to an improvement in the recovery rate and consequently to environmental conservation.

  However, in a copying machine or the like, an electrophotographic carrier that constitutes a two-component developer together with toner is difficult to reuse or recycle, and even if collected, it is buried without being subjected to any processing. Alternatively, measures such as incineration at high temperatures have been taken, and this has also caused a reduction in the recycling rate of copier parts. Among them, in particular, in a carrier in which the surface of fine magnetic particles is coated with a fluororesin, it is preferably used from the viewpoint of favorably controlling the chargeability. When a carrier coated with a fluororesin is treated at high temperature in the furnace, an acid gas is generated and the furnace material is damaged. In addition, a decomposition gas generated by the high temperature treatment, particularly hydrofluoric acid (hydrofluoric acid), is not suitable. In some cases, it is extremely toxic.

  On the other hand, an electrophotographic carrier is one of the basic materials in copying technology, and its powder characteristics including its electromagnetic characteristics, mechanical characteristics, and surface characteristics need to be controlled severely. is there. For this reason, when recycling the carrier, it is necessary to avoid adverse effects on these characteristics, which is also one of the causes of rejuvenation of the carrier for electrophotography. is there.

  By the way, as one of the techniques used for carrier recovery, a resin coated with a magnetic material can be melted, carbonized, decomposed, etc. in an oxygen-containing or non-oxygen atmosphere using a high-temperature firing furnace. There is a method of peeling by a method. This method is inexpensive in terms of equipment, and can treat together toner that is electrostatically attached to the carrier surface, toner that is firmly attached to the carrier surface, so-called impacted toner, and so on. There is an advantage. However, in the case of a carrier coated with a fluororesin, as described above, the generated gas may damage the furnace, and the hydrofluoric acid must be treated. There are inherent problems such as the possibility that the magnetic body itself, which is the core of the carrier, may be denatured.

  As another method, there is a method of recycling the carrier by mechanically peeling the coat resin on the surface of the magnetic material using a ball mill or the like. Specifically, the carrier collected from the market is housed in a container together with hard balls such as alumina balls, and a small amount of solvent and water are added to rotate the carrier surface so that the coating resin on the carrier surface is physically and forcibly forced. Although it is possible to peel the coating resin to some extent by this method, the carrier itself (specifically, the magnetic material itself) is crushed by the peeling action. (Refer to FIG. 7), and a problem that an organic substance such as a coating resin that adheres and remains on the surface of the magnetic particles is still required after the peeling process.

  Furthermore, as another technique used for carrier recovery, there is a so-called wet peeling method in which the coating resin is removed by bringing the carrier into contact with an organic solvent or a release agent. By adopting such a method, there is an advantage that the quality of the recovered magnetic material to be obtained can be secured to a high level without inviting the modification of the magnetic material, but it is necessary to recover the solvent or the release agent. In addition, the apparatus becomes complicated, and there are concerns about the danger of ignition and explosion and the environmental impact due to the use of flammable organic solvents.

  On the other hand, Patent Documents 1 to 4 disclose a method of separating a coating resin and a magnetic material of an electrophotographic carrier using supercritical water or subcritical water. However, all of the methods described in these patent documents are actually directed to a carrier coated with silicone resin, and the fluorine resin is removed from the carrier coated with fluorine resin. No detailed examination has been made on the method to do so, and therefore no consideration has been given to various problems caused by the decomposition of the fluorine resin. And in those patent documents 1-4, since the conditions of temperature: 300 degreeC or more and pressure: 20 Mpa or more are employ | adopted also in the state of supercritical water or subcritical water, such supercritical water or The subcritical water may modify the magnetic body itself (particularly the surface of the magnetic body) that is a carrier core coated with a fluororesin, and the magnetic body may not be able to exhibit the desired characteristics. There is a problem that the magnetic material from which the fluorine resin is removed by such a separation method cannot be reused as it is as the carrier core. Further, in the temperature and pressure regions as described above, a large and complicated device with pressure resistance is required for the separation operation, and the processing concentration of the carrier cannot be increased. Is a water / magnetic material (weight ratio), which can only be up to about 2.5, so that the amount of treatment per treatment is small and the treatment cannot be carried out inexpensively. There are inherent disadvantages.

JP 2003-98762 A JP 2003-96198 A JP 2001-290311 A JP 2002-244351 A

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that the magnetic material surface is coated without adversely affecting the characteristics of the magnetic material constituting the carrier. It is another object of the present invention to provide a treatment method that can effectively remove a resin containing a fluorine resin, and to remove a resin (coating resin) containing a fluorine resin from a carrier. An object of the present invention is to provide a method for advantageously recycling a carrier by reusing the magnetic material as it is and coating the surface with a predetermined resin.

  As a result of intensive studies to solve such problems, the present inventors have determined that the carrier coated with a fluororesin is a subcritical water, particularly at a temperature of 280 ° C. or lower and a pressure of at least 0. It is possible to effectively remove the fluorine resin coated on the surface of the magnetic material without adversely affecting the properties of the magnetic material itself by bringing it into contact with subcritical water under a state of 1 MPa or more. I found it.

Accordingly, the present invention has been completed on the basis of such knowledge, and the first aspect thereof is a method for processing a carrier constituting an electrophotographic developer together with a toner, the inner surface of a container In a processing vessel in which is made of polytetrafluoroethylene, a carrier having a magnetic surface coated with a resin layer containing at least a fluorine resin is in a state where the temperature is 280 ° C. or lower and the pressure is at least 0.1 MPa or higher. When the subcritical water and the carrier are brought into contact with each other in a ratio of 0.5: 1 to 2: 1 on a weight basis, the surface of the magnetic material of the carrier is coated. The present invention is also directed to a method for treating an electrophotographic carrier, wherein the resin is removed.

Furthermore, in the second aspect of the electrophotographic carrier processing method according to the present invention, the resin layer containing the fluorine resin is composed of a fluorine resin alone, or (A) a fluorine resin and (B) a polyester. A blend of at least one resin selected from the group consisting of resin, acrylic resin, silicone resin, polyethylene resin, polypropylene resin, polystyrene resin, polyacrylonitrile resin, polyurethane resin and epoxy resin, or (A) resin component And (B) a copolymer of a resin component, a graft polymer, or a block polymer.

In addition, in the third aspect of the present invention, a magnetic material represented by the following composition formula (I) is employed as the magnetic material of the carrier.
(MeO) _1-n (Fe ₂ O ₃ ) _{n + 1} (I)
[However, in composition formula (I), Me represents Co, Ni, Mn, Zn or Fe, while n satisfies 0 ≦ n ≦ 1. ]

  In addition, the present invention is also directed to the method for recycling the electrophotographic carrier as described above, and the magnetic material from which the coating resin layer has been removed from the electrophotographic carrier by the method as described above. The aspect of the present invention is a method for recycling a carrier for electrophotography using a magnetic material, which is used as it is, and is coated with a predetermined resin on the surface of the magnetic material to obtain a target carrier.

  According to the first aspect of the method for processing an electrophotographic carrier according to the present invention, the carrier coated with the resin layer containing a fluororesin has a temperature of 280 ° C., particularly in subcritical water. Hereinafter, the resin coated on the surface of the magnetic material is effectively removed and the resin is removed from the place where the pressure can be brought into contact with subcritical water at a pressure of at least 0.1 MPa. In the magnetic material, the desired characteristics are advantageously ensured without adversely affecting the powder characteristics including the electromagnetic characteristics, mechanical characteristics, surface characteristics, etc. It has characteristics.

  Therefore, as described above, in the magnetic body from which the resin containing the fluorine resin is removed, it can be advantageously reused (reused) as it is as a constituent material of the carrier.

Further, according to the process how the electrophotographic carrier according to the present invention, the resin coated on the magnetic member surface, so that more is more effectively removed.

  In addition, according to the method for recycling the electrophotographic carrier according to the present invention, the used carrier in the developer provided for use is simply and inexpensively regenerated into an electrophotographic carrier having ensured functionality, It can be used.

  Incidentally, an electrophotographic carrier to be processed is a component that constitutes a developer together with toner in a copying machine or the like, and is generally composed of fine magnetic particles and a resin, and the surface of the magnetic material is It has a structure coated with resin. In the present invention, in particular, the magnetic particles whose surfaces are coated with a resin layer containing a fluorine resin are effectively treated. The electrophotographic carrier includes a magnetic substance alone, a magnetic substance surface coated with a resin, and a carrier having various particle diameters. The present invention can be applied to any structure of the carrier. Is possible.

  More specifically, the magnetic material constituting the electrophotographic carrier is not particularly limited, for example, a ferromagnetic metal such as iron, cobalt, nickel, ferrite powder such as zinc, manganese, magnesium, etc. A conventionally well-known thing can be mentioned. Among these, since ferrite can arbitrarily control its magnetic properties, a metal oxide magnetic material represented by the composition formula (I) is particularly preferably employed. In the composition formula (I), Me represents Co, Ni, Mn, Zn or Fe, while n is a number satisfying 0 ≦ n ≦ 1, and is represented by the composition formula (I). Typical examples of the magnetic material include magnetite, hematite, and jacobsite, and these are usually sintered bodies. In addition, the average particle size of the magnetic material is generally about 10 to 100 μm.

  On the other hand, in the present invention, the resin constituting the surface of the electrophotographic carrier to be processed, that is, the resin coated on the surface of the magnetic material is a resin (fluorine resin) containing at least fluorine atoms as described above. Such fluorine resins include, for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, tetrafluoroethylene / hexafluoropropylene copolymer (PFEP), Examples thereof include polyvinylidene fluoride (PVDF) and perfluoroacrylate resin. A carrier coated with a resin containing at least one of these known fluorine resins is effectively treated in the present invention.

  As described above, the coating resin layer formed on the surface of the magnetic material only needs to contain at least a fluorine resin, or may be made of only a fluorine resin, or (A) a fluorine resin, (B) A blend of at least one resin selected from resins other than fluorine resins conventionally used in electrophotographic carriers, or the co-weight of (A) resin component and (B) resin component It may be composed of a polymer, a graft polymer, or a block polymer, and is further formed by sequentially applying a plurality of resins (A) resin component and (B) resin component to the surface of the magnetic material. Alternatively, a layer structure in which (A) a layer made of a resin component and (B) a layer made of a resin component are laminated may be adopted. Here, the resin component (B) is not particularly limited, and specific examples thereof include polyester resin, acrylic resin, silicone resin, polyolefin resin (for example, polyethylene resin, polypropylene resin, polystyrene resin), polyacrylonitrile. Examples thereof include a resin, a polyurethane resin, and an epoxy resin.

  Furthermore, in the coating resin layer as described above, various known additives may be uniformly contained as in the conventional carrier. For example, for the purpose of controlling the conductivity of the carrier itself, A conductive material such as carbon black may be contained. Needless to say, when various additives such as a conductive material are added, they can be appropriately contained in a normal addition amount.

  Such an electrophotographic carrier is processed in accordance with the present invention. At this time, the carrier to be processed can be used even if it is unused, but in general, it is used as a developer, and the carrier in the collected developer is processed. It becomes.

  When processing a used carrier, a large amount of toner remains in the collected developer in addition to the carrier, and the toner is electrostatically attached to the carrier. It is desirable that a pretreatment is performed in which the toner adhering to the carrier is roughly removed by a known separation operation such as air blowing, sieving, or a combination thereof.

  Then, by bringing the carrier thus obtained into contact with predetermined subcritical water according to the present invention, the coating resin layer containing the fluorine resin formed on the magnetic surface is advantageously removed. It is.

  More specifically, the subcritical water employed in the present invention is subcritical water that satisfies the conditions of a temperature of 280 ° C. or lower and a pressure of at least 0.1 MPa or higher among the subcritical waters ( (See FIG. 1). Such subcritical water has characteristics such as low ionic product, relative dielectric constant, and density compared to normal water, and it exhibits acid / base catalytic function, lipophilicity, and fluidity. In the present invention, a coating resin layer such as a fluorine resin is removed by oxidative decomposition or dissolution using the high reactivity. Further, the subcritical water employed in the present invention is more preferably one satisfying the conditions of temperature: 100 to 280 ° C. and pressure: 0.1 to 20 MPa among the temperature and pressure ranges as described above.

  When subcritical water or supercritical water exceeding the above range is used, the coating resin layer made of fluorine resin or the like formed on the carrier surface can be removed, but the carrier core body. Since the magnetic material (especially the surface of the magnetic material) tends to be denatured, the treated magnetic material cannot be reused as a carrier as it is. An operation such as heat treatment is required again. In addition, since the high temperature treatment is performed, acidic gas such as hydrofluoric acid having high reactivity is generated in the decomposition process, which may cause a problem that the treatment vessel made of SUS or the like is corroded. In particular, when processing a carrier to which toner adheres, various fragments are generated, and the processing container is easily corroded.

  By the way, in order to treat an electrophotographic carrier as described above with subcritical water under specific conditions according to the present invention, first, a carrier to be treated and water are accommodated in a predetermined treatment container.

  At this time, the treatment container is not particularly limited as long as it can withstand a temperature of 280 ° C. and a high pressure for forming a subcritical state, and is made of SUS that has been conventionally used. The pressure vessel can be used. In particular, in the present invention, since the above-described conditions are adopted, a PTFE container having excellent heat resistance and chemical resistance and a container whose surface is coated with such PTFE is used. In this way, if a processing container in which the inner surface of the processing container (the surface to be processed contacts) is made of PTFE is employed, even if acid gas or the like is generated, the processing container is corroded. Deterioration and the like are effectively suppressed or prevented, and wear due to contact between the carrier and the inner surface of the processing container is also advantageously suppressed. Incidentally, in the case of processing at higher temperature and higher pressure than the above-mentioned conditions, PTFE is difficult to use due to problems such as the melting point of PTFE, and higher energy cost and expensive equipment are required.

  In addition, the water contained in the treatment container is not particularly limited, and any ordinary water such as distilled water, purified water, or tap water can be used. It is desirable that purified water treated with a commercially available water purifier or the like is used because there is concern about the influence of chlorine contained for disinfection.

  And after sealing the processing container in which the carrier and water are accommodated, the processing container is heated under a general temperature rising condition so that the inside of the container has a desired temperature and pressure, whereby the processing container is heated. The water contained in the water is brought to a subcritical state. When the carrier is brought into contact with the subcritical water in this way, the coating resin that has been firmly and firmly fixed to the surface of the magnetic material is peeled, dissolved, melted, decomposed, etc. It is advantageously removed from the body surface. In addition, the reaction conditions at this time are milder than when supercritical water is used, so the influence on the magnetic particles is suppressed as much as possible, and the electromagnetic properties and mechanical properties of the magnetic materials are reduced. The powder characteristics such as surface characteristics are sufficiently maintained. When processing by contacting the carrier with subcritical water, in order to promote the reaction, insert a stirring shaft, rotate the processing container itself, or stir using a magnet or the like from the outside, It is also possible to stir the carrier in the container.

  In addition, the amount of water that gives subcritical water is not particularly limited, and is appropriately set according to the type of coating resin, and thus the type of carrier, but the weight of water and the carrier to be treated. It is desirable that the ratio is used in a ratio of water: carrier = 0.5: 1 to 40: 1. In other words, it is desirable that the water and the carrier are introduced into the processing container so that the liquid-solid ratio (water / carrier weight ratio) is 0.5 to 40. This is because if the amount of water present in the system is less than the above ratio, the coating resin on the carrier surface may not be sufficiently removed, and if it exceeds the above ratio, the processing container This is because the amount of carrier accommodated in the container is extremely small, and the processing cost increases. And among the above-mentioned ranges, the ratio of water: carrier = 0.5: 1 to 2: 1 can be more suitably employed, and by adopting such a ratio, the amount of carrier that can be processed at one time As a result, the processing cost can be further advantageously reduced.

  Furthermore, even in the time (reaction time) in which the carrier to be treated is brought into contact with the subcritical water, it is appropriately set according to the type of the coating resin, the liquid-solid ratio, etc. It is desirable that the time is ˜24 hours, more preferably 1 hour to 12 hours. This is because if the time is shorter than the above-mentioned time range, the coating resin on the carrier surface tends not to be sufficiently removed, and if the time is longer than the above-mentioned time range, the surface of the magnetic material may be modified. This is because it is economically disadvantageous.

  Thus, after the treatment with the subcritical water as described above, the treatment container is cooled, and the magnetic substance from which the strong adhesion with the coating resin including the fluorine resin is removed is taken out of the treatment water in the treatment container. It is. The magnetic material separated from the treated water and taken out is usually subjected to a washing treatment with water or a drying treatment.

  In the magnetic material thus obtained, the coating resin is effectively removed and the desired properties are advantageously ensured, so the virgin core material (uncoated resin, unused) As in the case of the magnetic particles, the carrier core material can be advantageously reused as it is. In addition, if such a magnetic material surface is coated with a carrier resin such as a fluorine resin or a silicone resin by a conventionally known method, an electrophotographic carrier as one component of the developer can be advantageously regenerated. Thus, recycling of the electrophotographic carrier can be realized extremely well.

  Hereinafter, some experimental examples including examples of the present invention will be shown to clarify the present invention more specifically. However, the present invention is not limited by the description of such experimental examples. It goes without saying that it is not something that you receive. In addition to the following examples, the present invention includes various changes, modifications, and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that improvements and the like can be added.

  In the following experimental examples, the amount of residual carbon in the magnetic material was evaluated using SEM / EDS (JEOL JSM-6360LV) and CHN coder (Yanaco Analytical Chemicals MT-5). Here, quantitative conditions by EDS (Energy Dispersion Spectrometer) were carried out at an acceleration voltage of 10 kV and an imaging magnification of 1,000. The surface state of the magnetic material was measured using XPS (ESCA-3300 manufactured by Shimadzu Corporation), while the crystal structure of the magnetic material was measured using an X-ray diffractometer (RINT-2000 manufactured by Rigaku Corporation).

<Experimental example 1>
A developer containing a carrier having the following composition obtained by coating the surface of a magnetic material (virgin magnetic material) having an average particle diameter of about 50 μm with a resin layer containing a fluorine resin was collected from the market. Then, the recovered developer was easily separated from the toner by blow-off to prepare a recovery carrier. Moreover, the scanning electron micrograph (SEM photograph) of this collection | recovery carrier was shown in FIG.
-Carrier composition-
Magnetic material: Fe ₂ O ₃ 63 parts by weight
MnO 17 parts by weight Resin layer: Perfluoroacrylate resin 5 parts by weight
15 parts by weight of polyester resin
Carbon black 0.5 parts by weight

  Next, 10 g of distilled water and 10 g of the recovered carrier were placed in a pressure-resistant container with a polytetrafluoroethylene lining having a capacity of 60 ml so that the liquid-solid ratio was 1, and the temperature was increased at 1 ° C./min. It heated to 250 degreeC with the temperature rate, and the process by subcritical water was performed by hold | maintaining for the predetermined time on the conditions of this temperature: 250 degreeC and pressure: 3MPa. During the treatment with the subcritical water, the contents in the pressure vessel were continuously stirred. Then, after cooling to room temperature and solid-liquid separation according to a conventional method, the magnetic material constituting the recovery carrier was recovered as a solid.

-Evaluation of residual carbon-
The morphology of the magnetic material thus obtained was observed, and an SEM photograph of the treatment time (referred to as the retention time after the temperature rise; hereinafter the same) was 2.5 hours is shown in FIG. By comparing the SEM photograph of FIG. 3 with the SEM photograph of FIG. 2 before the treatment with subcritical water, it can be recognized that the resin layer on the surface of the magnetic material is effectively peeled off. Further, it has been clarified that there is no abnormality in the form of the magnetic material, and it can be used as it is and reproduced as a carrier.

Further, the carbon content of the magnetic material obtained by the treatment with subcritical water and the carbon content of the unused carrier were measured using a CHN coder, and the following values were obtained from the obtained values:
Carbon residual ratio (%) = [Measured carbon amount after subcritical water treatment (wt%)]
÷ [Measured carbon content of unused carrier (wt%)] x 100
As a result, the carbon residual rate (%) was calculated. As a result, the carbon residual rate became 2% after 5 hours. The carbon residual rate of the virgin magnetic material was 2%, and the coating resin on the carrier surface could be completely removed by treatment with subcritical water for 5 hours.

-Crystal structure analysis-
Furthermore, the crystal structure analysis of the magnetic material obtained above (processing time: 6, 12, 24 hours) was performed, and the obtained X-ray diffraction graph is shown in FIG. The X-ray diffraction conditions were Cu Kα 50 kV-100 mA. In addition to the magnetic bodies (b) to (d) obtained above, FIG. 4 also shows an X-ray diffraction pattern of the virgin magnetic body (a) for comparison. From FIG. 4, the crystal forms of the obtained magnetic bodies (b) to (d) are all Jacobsite, and there is no difference in crystal size and interplanar spacing compared to the virgin magnetic body (a). From this, it was confirmed that there was no change in the crystal form and crystal form.

-Analysis of surface condition-
Moreover, the surface state analysis of the magnetic material obtained above was performed, and the XPS spectrum was shown in FIG. In addition to the magnetic body (b) obtained above, FIG. 5 shows a virgin magnetic body (a) that is not coated with a resin and a supercriticality in Experimental Example 5 described later for comparison. The XPS spectrum of the magnetic substance (c) obtained by treatment with water is also shown. As is clear from FIG. 5, it can be seen that the magnetic material treated with subcritical water has no change in Fe2p and is not denatured.

  From the above results, the obtained magnetic material was not modified and the coating resin was completely removed. As a magnetic material for giving a carrier, it was advantageous as it was or after the surface was coated with the resin. It became clear that it could be used for

<Experimental example 2>
A developer similar to that in Experimental Example 1 was collected from the market. Then, the collected developer was passed through a 20 micron mesh sieve, and the toner electrostatically attached to the carrier surface was removed by decompressing from the bottom of the mesh to prepare a recovered carrier.

  Then, 5 g of the recovered carrier and 10 g of distilled water (liquid-solid ratio: 2) are put into a pressure-resistant container with a Teflon (registered trademark) lining, and in the same manner as in Experimental Example 1, subcritical water is used. Processing was carried out to obtain a magnetic material. However, the processing time was 2 hours.

  When evaluation of residual carbon, crystal structure analysis, and surface state analysis of the obtained magnetic material were performed in the same manner as in Experimental Example 1, the carbon residual ratio was 4%, which changed to an X-ray diffraction pattern and an XPS spectrum. Was not recognized.

<Experimental example 3>
5 g of a carrier in which a coating resin layer made of a blend of a polyester resin and a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin is formed on the surface of a magnetic material made of ferrite containing MnO and having an average particle diameter of about 50 μm, Put together with 3 g of distilled water in a Teflon-lined pressure vessel with a capacity of 80 ml (liquid / solid ratio: 0.6), and after sealing, heat to 280 ° C. at a rate of 1 ° C./min, and Then, under the conditions of such temperature: 280 ° C. and pressure: 3 MPa, the treatment with subcritical water was performed by maintaining for 2 hours, and then the same operation as in Experimental Example 1 was performed to obtain a magnetic material.

  Then, evaluation of residual carbon, crystal structure analysis, and surface state analysis of the obtained magnetic material were performed in the same manner as in Experimental Example 1. As a result, the carbon residual ratio was 5.5%, and the acceleration voltage was 15 kV. Even when SEM observation was performed, no residual resin was observed, and there was no abnormality in the form. In addition, no change was observed in the X-ray diffraction pattern and XPS spectrum.

<Experimental example 4>
The recovery carrier prepared in Experimental Example 2 is used so that the liquid-solid ratio becomes 0.4, and is maintained for 3 hours under the conditions of temperature: 280 ° C. and pressure: 2 MPa. Thereafter, the same operation as in Experimental Example 1 was performed to obtain a magnetic body.

  Then, evaluation of residual carbon, crystal structure analysis, and surface state analysis of the obtained magnetic material were performed in the same manner as in Experimental Example 1. The carbon residual ratio was 15%. Resin residue was observed in some places by SEM observation.

<Experimental example 5>
The recovery carrier prepared in Experimental Example 1 was treated in the same manner as Experimental Example 1 with a liquid-solid ratio of 1: However, as treatment conditions, the conditions (temperature: 380 ° C., pressure: 25 MPa) at which water is in a supercritical state are adopted, and the carrier is held for 12 hours under such temperature and pressure conditions, thereby using supercritical water. The treatment was performed, and then the same operation as in Experimental Example 1 was performed to obtain a magnetic material.

  And when the evaluation of the residual carbon of the obtained magnetic substance, the crystal structure analysis and the surface state analysis were performed in the same manner as in Experimental Example 1, the carbon residual ratio was 2%, and even when SEM observation was performed, There was no residual resin, and there was no abnormality in the form. However, as shown in FIG. 5, in the XPS spectrum, a new peak that does not exist in the virgin magnetic material appeared at a binding energy of Fe2p of about 715 eV. The reason for the appearance of this peak is not clear, but it is understood that the surface state of the magnetic material was changed by the treatment with supercritical water. Further, in the XPS spectrum, the peak area near about 711 eV is larger than that of the virgin magnetic material and is also shifted to the high energy side, so it is clear that the surface state was changed. is there.

<Experimental example 6>
The recovered carrier prepared in Experimental Example 1 was heat-treated at 400 ° C. for 2 hours in an air atmosphere, whereby the resin layer formed on the surface of the magnetic material was thermally decomposed. Then, an SEM photograph of the heat-treated carrier was taken and shown in FIG.

  As is apparent from FIG. 6, even when the treatment is performed at a high temperature (400 ° C.) for 2 hours, the resin and toner are not completely removed on the surface of the magnetic material. However, in order to completely remove the resin and toner by a heat treatment in an air atmosphere, a temperature treatment of 600 ° C. or higher is necessary. If such a temperature is adopted, the state of the surface of the magnetic material is denatured. Therefore, it cannot be reused as a magnetic material.

<Experimental example 7>
The recovered carrier prepared in Experimental Example 1 is put into a container together with an alumina ball having a diameter of 5 mm, and a small amount of a solvent and water are added thereto, and then the container is rotated for 24 hours to thereby obtain a resin on the carrier surface. The layer was forced to peel mechanically. And the SEM photograph of the carrier from which the resin layer was peeled off with alumina balls was taken and shown in FIG.

  As is clear from FIG. 7, when the resin layer is mechanically peeled off with an alumina ball, the magnetic body itself is also crushed. Moreover, the process of isolate | separating organic substance is further required after operation.

It is a state diagram of water for explaining subcritical water employed in the present invention. 3 is an SEM photograph of the surface of a recovered carrier in which a developer recovered from the market is separated from toner by blow-off. It is a SEM photograph of the magnetic body obtained in Experimental Example 1, and is a SEM photograph of the carrier surface after the recovered carrier shown in FIG. 2 is treated with subcritical water according to the present invention. 6 is an X-ray diffraction diagram showing the results of crystal structure analysis performed in Experimental Example 1. FIG. 3 is an XPS spectrum showing the result of surface state analysis performed in Experimental Example 1. It is a SEM photograph of the carrier surface which thermally decomposed the collection | recovery carrier shown by FIG. It is a SEM photograph of the carrier surface which processed the collection carrier shown in Drawing 2 using alumina beads.

Claims (4)

A method of processing a carrier constituting an electrophotographic developer together with a toner, wherein the inner surface of the container is made of polytetrafluoroethylene, and the magnetic surface is coated with a resin layer containing at least a fluorine resin. The carrier thus obtained is subcritical water at a temperature of 280 ° C. or lower and a pressure of at least 0.1 MPa, and the subcritical water and the carrier have a weight ratio of 0.5: 1 to 2: 1. A method for processing an electrophotographic carrier, wherein the resin coated on the magnetic surface of the carrier is removed by bringing the carrier into contact at a ratio . The resin layer containing the fluorine resin is composed of a fluorine resin alone, or (A) a fluorine resin and (B) a polyester resin, an acrylic resin, a silicone resin, a polyethylene resin, a polypropylene resin, a polystyrene resin, and a polyacrylonitrile resin. , A blend of at least one resin selected from the group consisting of polyurethane resin and epoxy resin, or a copolymer, graft polymer, or block polymer of (A) resin component and (B) resin component processing method of the electrophotographic carrier according to claim 1 which is composed of. The processing method of the carrier for electrophotography of Claim 1 or Claim 2 with which the magnetic body of the said carrier is shown by the following compositional formula (I).
(MeO) _1-n (Fe ₂ O ₃ ) _{n + 1} (I)
[However, in composition formula (I), Me represents Co, Ni, Mn, Zn or Fe, while n satisfies 0 ≦ n ≦ 1. ] The magnetic material from which the coating resin layer has been removed from the electrophotographic carrier by the method according to any one of claims 1 to 3 is used as it is, and a surface of the magnetic material is coated with a predetermined resin. A method for recycling an electrophotographic carrier using a magnetic material, wherein the carrier is a target carrier.

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