JP3267750B2 - How to regenerate your career - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier for a developer used in electrophotography and the like, and more particularly, to a method for recycling a recovered carrier.

[0002]

2. Description of the Related Art There has been proposed a method of regenerating a carrier whose characteristics as a carrier have been deteriorated due to an attached substance on the surface. Both have the same feature of removing the deposits on the surface, and the means for removing them are different. For example, a method of baking the carrier at a specific temperature to remove the deposits and regenerate the carrier (Japanese Unexamined Patent Publication No. 47-12286), first removes the deposits on the carrier surface as much as possible by air blow, and then heats the carrier to remove the deposits. After burning off the adhered toner, the carrier is subjected to a heat treatment to adjust the electric resistance value (JP-A-63-21294).
5) a method of cleaning the carrier by washing the carrier with a solvent to dissolve the toner adhering to the surface or dispersing the toner in the solvent to clean the carrier (JP-A-3-89254).

[0003] However, the method of burning the deposits on the surface of the carrier is such that combustion residues such as ash remain to change the characteristics of the surface of the carrier. The problem is that it takes a long time. Further, the method of dissolving or dispersing the toner on the carrier surface in a solvent to clean the toner surface may damage the surface coating of the carrier if the characteristics of the solvent are not selected, and may consume expensive solvent. There is a problem that the amount is large.

[0004]

SUMMARY OF THE INVENTION The present invention seeks to provide a carrier regenerating method that does not consume expensive materials, does not complicate the steps and equipment, and can recover the carrier performance in a short time. Is what you do.

[0005]

In order to solve the above-mentioned problems, the present invention provides a structure in which a carrier having deposits is mixed with an abrasive such as silicon carbide (SiC) or alumina (Al ₂ O ₃ ). This is a carrier regenerating method in which, after stirring to remove deposits on the carrier surface, the cleaned carrier is separated from the mixture. At that time the ratio of the particle size r _c of the carrier and the particle size r _g of the abrasive is 3 or more, i.e., particularly preferably a r _c / r _g ≧ 3. The regenerating method of the present invention forcibly removes the toner substance (particularly, binder resin) attached to the carrier surface by using an abrasive. And does not remain on the particle surface, and there is no fear of denaturation of the core material (ferrite, magnetite, iron, etc.) due to heat. Further, unlike the method of dissolving or dispersing the toner substance in a solvent, the toner substance can be completely removed from the particle surface without limiting the materials which can be regenerated and without worrying about waste liquid treatment.

Hereinafter, the present invention will be described in more detail. The present invention collects carrier particles degraded by a developing operation,
The collected carrier particles are stirred and mixed with an abrasive for an appropriate time to remove the toner fused to the particle surface, and then the carrier is separated from the mixture. In the step of stirring and mixing with the abrasive, any of general mixers may be used, and examples thereof include a ball mill, a ribbon blender, and a universal mixing stirrer. By this step, the toner substance attached to the carrier surface can be efficiently removed. In the case of a resin-coated carrier, the resin-coated layer can be removed together with the toner substance, but there is no particular problem by selecting an appropriate abrasive, a type of stirrer, and determining stirring conditions.

The abrasive used in the present invention varies depending on the material of the carrier and the type of the coating resin, but silicon carbide and alumina fine particles are optimal. In addition, separation of the toner from the collected developer (however, toner not fused to the carrier) and separation of the abrasive after the stirring and mixing step are performed by a general air classifier and a method using a particle size difference. Used.

Further, the abrasive used must completely remove the spent toner on the carrier surface and minimize the damage to the carrier surface. Further, since the carrier must be completely separated from the carrier regenerated in the separation step, it is preferable to use an abrasive having a particle size of 1/3 or less of the average particle size of the carrier.

As the carrier applicable to the reproducing method of the present invention, a carrier for electrophotographic developer known per se used in this field can be used. For example, iron oxide (magnetite), reduced iron, copper, ferrite, Examples include particles of nickel, cobalt, and the like, and alloys of zinc and aluminum. As the coating resin, acrylic resin, epoxy resin, silicone resin, urethane resin, polyacetal resin, polyamide resin, polycarbonate resin,
Any of known materials such as a phenol resin, a vinyl acetate resin, a cellulose resin, a polyolefin resin, a fluororesin, and an amino resin may be used. The carrier reproduced in this way can be restored to the same characteristics as a new carrier.

[0010]

The present invention will be specifically described below with reference to examples. In addition, the amount (part) of each component described in Examples and Comparative Examples is part by weight. Example 1 100 parts of a silicone resin (solid content: 20%) 100 parts of toluene 100 parts of carbon black 2 parts of this coating layer forming liquid was formed on a surface of 1000 parts of spherical ferrite having an average particle diameter of 100 μm using a fluidized bed type coating apparatus. As a result, carrier particles I were obtained. On the other hand, (manufacture of toner) A mixture composed of 87 parts of styrene-n-butyl methacrylate copolymer, 10 parts of carbon black, and 3 parts of metal-containing azo dye was melt-kneaded with a hot roll at 120 ° C., then cooled and solidified, and jetted. It was pulverized with a mill and classified to obtain toner particles I having an average of 10 μm. 97.5 parts of the carrier particles I and 2.5 parts of the toner particles I were mixed to form a developer A, and the following test was performed.

Test The process of developing and transferring the latent image on the selenium photoreceptor at a speed of 40 times per minute using the above developer was repeated 200,000 times while supplying toner. As a result of this test, the charge amount at the start of the test was -21.3 μc / g, and the image was clear. However, as the number of copies increased, the charge amount decreased, and
After the use of 100,000 sheets, the charge amount was as low as -12.1 μc / g, and the image had much background stain. The developer was taken out, and first, the toner electrostatically attached to the carrier was removed by blow-off.

Next, this carrier was stirred under the following formulation and conditions.

[0013] 100 parts of a carrier, SiO ₂ (Radiolite # 200, Shiraishi Calcium Co., Ltd.) 5 parts of an average particle diameter of 6.2 μm are stirred for 1 hour by a ball mill. After completion of the stirring, only the carrier is recovered using a cyclone classifier.

When the surface of the regenerated carrier was observed with a SEM, all of the abrasive and shavings were removed.
Some cracks of the silicon resin on the carrier surface were found, but within the allowable range. Next, this reproduction carrier 97.5
And 2.5 parts of the toner were mixed and used as a developer, and the same copying test was performed. As a result, the charge amount at the start of the test was −
The charge amount was also recovered at 18.5 μc / g, and the image was clear with no background staining.

Example 2 A test was conducted in the same manner as in Example 1. As a result, the charge amount at the start of the test was -20.9 μc / g, and after the use of 200,000 sheets, it was -1.
The image was as low as 1.3 μc / g, and the image had much background stain. The toner that electrostatically adhered to the carrier was removed from the deteriorated developer by blow-off.

Next, 100 parts of the carrier and 8 parts of Al ₂ O ₃ particles (average particle size: 3.5 μm) were stirred for 2 hours by a ball mill. After completion of the stirring, only the carrier was recovered by a cyclone classifier. When the surface of the regenerated carrier was observed by SEM, all the Al ₂ O ₃ particles and shavings were removed, and there was no damage to the coating on the carrier surface. Next, when this regenerated carrier was evaluated in the same manner as in Example 1,
The charge amount at the start of the test was -20.2 μc / g, which was the same as that of the new agent, and the image was good.

Example 3 Acrylic resin 30 parts Toluene 100 parts Ferrite (80 μm) 1000 parts A coating layer was formed using the above-mentioned formulation using a fluidized bed type coating apparatus to obtain carrier particles II. A developer was prepared by mixing 96 parts of the above carrier II and 4 parts of the toner particles I described in Example 1. The step of developing and transferring the latent image on the selenium photosensitive member at a speed of 25 times per minute using this developer was repeated 200,000 times.

As a result, the charge amount at the start of the test was -14.8.
Although the image was good at μc / g, the charge amount decreased as the number of copies increased, and the charge amount after using 200,000 sheets was −
The image was as low as 7.5 μc / g, and the image was also much soiled. The developer was taken out, and first, the toner electrostatically attached to the carrier was removed by blow-off. Next, this carrier was stirred under the following formulation and conditions.

Carrier 100 parts SiC (GC-4000) 2 parts The mixture was stirred for 30 minutes by a ball mill, and after the stirring was completed, only the carrier was recovered using a sieve having a mesh of 350 mesh (44 μm). With this carrier, a developer was prepared in the same manner as in the case of a new carrier. As a result, the charge amount was -13.9 μm.
c / g was the same as the new agent, and the image was good.

Comparative Example 1 The developer obtained by copying 200,000 sheets in Example 1 was mixed again only by removing the toner adhering to the carrier electrostatically by blow-off. When the agent was mixed again, the charge amount was -13.2 μc. /
g and the image was not improved. Comparative Example 2 The developer obtained by copying 200,000 sheets in Example 3 was blow-off only by removing the toner adhering to the carrier electrostatically, and the agent was mixed again. The charge amount was -7.2 μc.
/ G and the image was not improved.

[0021]

[0022]

[Table 1]

Examples 1 to 3 show that the developer can be regenerated at low cost by using this method. Also,
A developer was prepared using a regenerated carrier and evaluated.
Even if the image was copied for 10,000 copies, the image was obtained in good condition without any background stain. In the examples, when SiO ₂ is used, a slight damage of the coat film is observed. Therefore, it is preferable to use Al ₂ O ₃ or SiC as a polishing material in order to obtain a further effect. Although a known method can be used for separating the abrasive and the carrier, sieving is preferable in consideration of productivity. For that purpose, the maximum particle size of the abrasive needs to be sufficiently smaller than the particle size of the carrier.

[0024]

As described above, according to the present invention, a carrier having deteriorated characteristics due to adhesion of toner can be efficiently reproduced by a relatively simple method.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hidefumi Gohara 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (56) References JP-A-3-89254 (JP, A) JP-A Sho 58-97057 (JP, A) JP-A-61-140952 (JP, A) JP-A-62-248998 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/10

Claims (3)

(57) [Claims] 1. A method for regenerating a carrier, comprising mixing an abrasive with a carrier having an adhered substance, stirring the carrier, removing the adhered substance on the carrier surface, and separating the carrier from the mixture. 2. The method for regenerating a carrier according to claim 1, wherein the abrasive is silicon carbide or alumina. 3. The method according to claim 1, wherein the ratio of the particle size of the carrier to the particle size of the abrasive is 3 or more.
The carrier regeneration method as described.