JP3290130B2 - Toner recycling type developing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an image forming apparatus such as a copying machine or a printer using electrophotography, and develops toner remaining on the surface of a photoreceptor after a process of transferring to a recording sheet. The present invention relates to a toner recycling type developing method for reuse as an agent and a developing device suitable for carrying out the method.

[0002]

2. Description of the Related Art A dry developer applied to the developing system of the image forming apparatus includes a two-component developer in which a carrier (ferrite powder, iron powder, glass beads, etc.) which is a magnetic substance is mixed with a toner, It is roughly divided into a one-component developer in which a magnetic powder is carried on the toner itself. Each developer contains a binder resin and a colorant as main components, and also includes a wax for improving low-temperature fixability to a recording sheet and a polar (positive or negative) charge. A charge control agent or the like is added. The toner is manufactured into powder through a process such as melt-kneading, pulverization, and classification after these materials are mixed in a predetermined formulation.Finally, the toner is used for controlling fluidity, chargeability, cleaning properties, storage stability, and the like. , Silica, titanium oxide,
External additives such as alumina and various kinds of resin fine particles are adhered and surface-treated, and finally used as a developer.
By the way, in recent image forming apparatuses, there is a mechanism for reusing (recycling) toner in a developing apparatus for the purpose of resource saving, reduction of running cost, etc., or as a measure against stricter waste regulations. Additional ones are provided. When reusing toner,
After the toner image developed on the surface of the photoreceptor is transferred to the recording sheet, the toner (part of the toner image) remaining on the surface of the photoreceptor is scraped off with a cleaning blade or a fur brush, and the toner is removed by a developer. Is generally transported to a developer container in which the developer is stored and collected in unused developer.

[0003]

However, the toner collected as described above is scraped off from the photoreceptor by a cleaning blade or is conveyed to a developer container, When being stirred in the container, it receives a thermal or mechanical load, so that the above-mentioned external additive is buried in the toner (mainly in the binder resin) and the function of the external additive is sufficiently improved. There was a case that was not exhibited.
More specifically, image defects such as fogging that occurs on an image after fixing is deteriorated particularly due to a decrease in the chargeability of the toner and a deterioration in the rise of the charge. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a toner recycling type developing method and an apparatus thereof in which deterioration of fog caused by burying of an external additive is effectively prevented and a toner life is extended.

[0004]

According to the toner recycling developing method of the present invention, an electrostatic latent image formed on the surface of a photoreceptor is developed with a developer containing toner to visualize a toner image. After the toner image is transferred to the recording sheet, the toner remaining on the photoreceptor is collected, and the toner having the following materials and physical properties is used in a developing method in which the collected toner is reused for visualization. It is characterized by: As a material, a binder resin and a colorant are used as main components, and a mixture thereof is, for example, melt-kneaded,
It is manufactured into powder through processes such as pulverization and classification. The above-mentioned external additive is adhered to this powder and subjected to a surface treatment to obtain a toner to be used. Regarding its physical properties, a sample compressed and solidified at 500 kg / cm ² by a high-pressure press or a sample which was melted in an oven at 180 ° C. and then solidified by standing at room temperature was subjected to JIS B7725 and JISZ.
Vickers hardness determined by 2244 is 16.0H
V0.01 (10 g) or more, preferably 17.0 HV0.0
1 (10 g) or more. By having such a hardness, the external additive is prevented from being buried in the toner even when the toner is subjected to a thermal or mechanical load in a recovery step or the like. Therefore, the function of the external additive is always maintained, the life of the toner is extended, and image defects due to deterioration of fog are prevented.

According to the present invention, the binder resin constituting the main component of the toner has a Vickers hardness of 15.0 HV 0.01 (10 g) or more, preferably 16.0 HV 0.01 (10 g), according to the above-mentioned measuring method. ) It is characterized by using the above. This ensures that the Vickers hardness of the toner is as described above, and further increases are expected, so that the effects of the present invention are further exhibited.

On the other hand, a toner recycling type developing device according to the present invention comprises: a developer container for storing a developer containing toner;
The developer contained in the developer container is carried, and the carried developer is brought close to the photoconductor, so that toner is attracted to the electrostatic latent image formed on the surface of the photoconductor and the electrostatic latent image is formed. And a toner recovery unit that recovers the toner remaining on the photoreceptor and returns it to the developer container after the toner image is transferred to the recording sheet. It is characterized in that the toner is the same as in the above-mentioned developing method. This developing device is very suitable for carrying out the above-mentioned developing method, and has the same effect that the function of the external additive is always maintained and image defects due to deterioration of fog are prevented. .

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 conceptually shows an image forming means of a copying machine. Figure marks No. 1 denotes a photosensitive drum which rotates in the arrow A direction (photoconductor), the photosensitive drum 1
Around the corona charger 2, the optical system 3, the developer (one-component or two-component) 6 according to the rotation direction.
Container 4a, developing sleeve (developer) 4b, corona transfer device 5, cleaning blade 9
a, the static elimination means 10 are arranged in this order. Recording sheet shown in sign-7 is adapted to be transported from the right side in the figure passes between the photosensitive drum 1 and the corona transfer device 5,
A heating / pressurizing type fixing roller pair 8 is disposed at the transport destination. The cleaning blade 9a removes the toner remaining on the surface of the photosensitive drum 1 after the transfer (part of the toner image:
The collected toner 6b is scraped off, and the scraped toner 6b is returned to the developer container 4a via the collection conveyance path 9b. In this case, the toner collecting means 9 is constituted by the cleaning blade 9a and the collecting and conveying path 9b, and the developing device 4 is constituted by a combination of the collecting means 9, the developer container 4a and the developing sleeve 4b.

The image forming process by the image forming means includes:
It is as follows. First, the surface of the rotating photosensitive drum 1 is uniformly charged by corona discharge of the corona charger 2, and then an electrostatic latent image is formed on the surface of the photosensitive drum 1 by exposure of the optical system 3. . The developing sleeve 4b rotates while adsorbing the developer 6 contained in the developer container 4a, and the toner in the developer 6 (in the case of a one-component system, all of the developer 6 is toner) is exposed to light. It is attracted to the electrostatic latent image formed on the surface of the body drum 1 by the action of the opposite polarity. Thus, the electrostatic latent image is visualized as the toner image 6a.
Next, the recording sheet 7 is transferred to the photosensitive drum 1 and the corona transfer device 5.
And the toner image 6a is superimposed on the toner image 6a, and a transfer charge is given from the back surface by the corona transfer device 5, whereby the toner image 6a is transferred onto the recording sheet 7. Thereafter, the recording sheet 7 passes between the fixing roller pair 8, and at that time, the toner image 6a is fixed on the recording sheet 7. On the other hand, the toner 6b remaining on the surface of the photosensitive drum 1 without being transferred to the recording sheet 7 is scraped off by the cleaning blade 9a, thereby
Is cleaned, and thereafter, the charge is removed by the charge removing means 10. The toner 6b scraped off by the cleaning blade 9a is returned to the developer container 4a via the recovery conveyance path 9b, and is used again.

The developer is a one-component developer or a two-component developer. In the case of a one-component developer, the toner itself is used as the developer. In the case of a two-component developer, a carrier is mixed with the toner. The developer is used as a developer. Hereinafter, the materials constituting the toner according to the exemplary embodiment will be described.

(1) Main components <Binder resin> Binder resins include styrenes such as styrene, α-methylstyrene and chlorostyrene, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and acrylic acid. Acrylic esters such as octyl, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, methacrylic esters such as stearyl methacrylate, glycidyl methacrylate, acrylonitrile, maleic acid, maleic ester, vinyl chloride, Homopolymerized vinyl monomers such as vinyl acetate, vinyl benzoate, vinyl methyl ketone, vinyl hexyl ketone, vinyl methyl ether and vinyl isobutyl ether, or copolymerized vinyl resins such as styrene resins and acrylic resins Resin, Epoxy resins, polyester resins, polyurethane resins and the like are used.

<Colorant> The colorant is carbon black,
Aniline blue, calco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal and the like are used alone or in combination. The coloring agent needs to have a sufficient content of a sufficient concentration to form a visible image, and for example, is contained in an amount of about 1 to 20 parts by weight based on 100 parts by weight of the binder resin. .

(2) Other Additive Materials The toner of the present invention contains the above-mentioned binder resin and colorant as main components. In addition to these, the following materials are appropriately added. <Low Melting Wax> The low melting wax is added for the purpose of lowering the melting start temperature of the toner to improve the low-temperature fixability, and synthetic wax, petroleum wax and the like are used.
Examples of the synthetic wax include polypropylene wax and Fischer-Tropsch wax, and examples of the petroleum-based wax include paraffin wax, microwax, and petrotam. Other waxes include natural waxes such as carnauba wax, rice wax, and candelilla wax, and synthetic fats and oils. <Charge Control Agent> The charge control agent is added to impart polarity, and is divided into those for positively charged toner and those for negatively charged toner. Nigrosine dyes, quaternary ammonium salts, pyridinium salts, azines and the like are used for positively charged toners. For negatively charged toner, azo-based metal-containing complexes and salicylic acid-based metal complexes are used. <Release Agent> The release agent is added in order to ensure releasability between the heat roller for fixing and the toner, and low molecular weight polypropylene, low molecular weight polyethylene or the like is used.

(3) External additive In the toner of the present invention, the above-mentioned materials are mixed in a predetermined mixture,
The mixture is manufactured into a powder through processes such as melt-kneading, pulverization, and classification. Then, the powder is subjected to a surface treatment by mixing the following external additives to obtain a toner to be used. The external additives are added for controlling the fluidity, chargeability, cleaning property, storage stability, etc. of the toner, and silica, alumina, talc, clay, calcium carbonate, magnesium carbonate, titanium oxide or various resin fine particles are used. Used. The external additive is added at a ratio of about 0.3 to 3 parts by weight based on 100 parts by weight of the main component. Also,
In performing the surface treatment of the main component with the external additive, a method of mixing and stirring the main component and the external additive with a general stirrer such as a turbine-type stirrer, a Henschel mixer, or a super mixer may be used. .

The toner of the present invention is prepared by a high-pressure press machine.
Sample compressed and solidified at 00 kg / cm ² , or 180
JIS B7725 and JIS Z22
The Vickers hardness obtained by the method of No. 44 is 16.0 HV.
01 (10 g) or more. In order to impart such physical properties, for example, to a binder resin constituting most of the main components,
The Vickers hardness can be adjusted to 16.0 HV 0.01 (10 g) or more by using a material having a Vickers hardness of 15.0 HV 0.01 (10 g) or more and adding a main component other than the binder resin. Vickers hardness of binder resin is 15.0 HV 0.01
(10 g) or more, or 16.0 HV 0.01 (10 g) or more, the Vickers hardness of the toner will surely be 17.0 HV 0.01 (10 g) or more and further increase is expected. The effect is more preferably exhibited. A binder resin having a Vickers hardness having the above value can be obtained by appropriately selecting the monomer composition as described above, or by appropriately controlling polymerization conditions and the like during resin production. When the toner has the hardness as described above, the external additive is prevented from being buried in the toner even if the recovered toner is subjected to a thermal or mechanical load in the recovery step or the like. Therefore, even when reuse is repeated, the function of the external additive is always maintained, so that the life of the toner is prolonged, and image defects due to deterioration of fog are always prevented.

[0015]

Next, the effects of the present invention will be clarified by Examples 1 and 2 based on the present invention and Comparative Examples 1 and 2 based on the present invention. In each of the examples and comparative examples, as described below, the amounts of the binder resin, the colorant, the release agent, and the charge control agent as the main components, and the amounts of the external additives were all the same.・ Binder resin 100 parts ・ Coloring agent carbon black 5 parts ・ Release agent polypropylene wax 3 parts ・ Charge controlling agent Metal-containing complex salt dye 1 part ・ External additive hydrophobic silica 0.3 parts

Then, the kind of the binder resin is changed for each of Examples and Comparative Examples, and the above-mentioned colorant, release agent and charge controlling agent are mixed to produce a main component of the toner, and further, an external additive is added. To produce a toner. Table 1 shows the type of binder resin used in each of the examples and comparative examples, and the Vickers hardness HV 0.01 (10 g) of the binder resin and the toner. The Vickers hardness was determined according to JIS B7725 and JIS Z2244 for a sample that was melted in an oven at 180 ° C. and then solidified by standing at room temperature. The method for producing the toner is as follows. The binder resin, the colorant, the release agent and the charge control agent are mixed as described above using a super mixer, and the mixture is hot-melted and kneaded at 120 ° C. by a pressure kneader to obtain a kneaded product. After pulverizing with a mill, the powder was classified by a dry airflow separator to obtain a powder composed mainly of toner. Next, by mixing the above-mentioned external additives with 100 parts by weight of the powder using a Henschel mixer,
Surface treatment was performed by attaching hydrophobic silica to the powder surface.

[0017]

[Table 1]

Next, Examples 1 and 2 and Comparative Examples 1 and 2
And 4 parts by weight of the toner, and 100 parts by weight of the ferrite carrier were mixed with these toners. A commercially available copying machine equipped with a toner recycling system (Matsushita Electric Industrial Co., Ltd .: P
D-3018), continuous copying was performed up to 10,000 sheets, and the image density and fog in the non-image area were measured at the initial stage and after 10,000 sheets. The image density was measured on a solid image by a reflection densitometer (RD-914, manufactured by Macbeth), and the fog was measured by a colorimeter (ZE2000, manufactured by Nippon Denshoku Industries Co., Ltd.). Table 2 shows the results. Note that the image density needs to be 1.35 or more for practical use, and the fog needs to be 1.00 or less for practical use.

[0019]

[Table 2]

As can be seen from Table 2, in the toners of Examples 1 and 2 satisfying the conditions of the present invention, it was confirmed that neither the image density nor the fog had a practical problem.
On the other hand, in each of Comparative Examples 1 and 2, there is no practical problem with respect to the image density in any case, but fog after 10,000 sheets was significantly deteriorated and image defects occurred.

[0021]

As described above, according to the present invention,
By using a toner having the above-mentioned predetermined hardness or more, even if the toner is subjected to a thermal or mechanical load in the recovery step or the like, the external additive is prevented from being buried in the toner, and thus, even if the recycling is repeated. The function of the external additive is always maintained, the toner life is extended, and image defects due to deterioration of fog are always prevented.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an image forming unit according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum (photoreceptor), 4a ... Developer container, 4
b: developing sleeve (developer), 6: developer, 6a: toner image, 6b: collected toner, 7: recording sheet, 9: toner collecting means.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G03G 21/10 G03G 9/08 361 21/00 326 (72) Inventor Takeshi Matsumoto 3-1 Yomibacho, Shizuoka-shi, Shizuoka (56) References JP-A-6-282107 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/00-9/08 G03G 15/08-15/095

Claims (2)

(57) [Claims] 1. An electrostatic latent image formed on a surface of a photoreceptor,
After developing with a developer containing toner, the toner image is visualized as a toner image. On the other hand, after the toner image is transferred to a recording sheet, the toner remaining on the photoreceptor is collected, and the collected toner is visualized. in the toner recycling type developing method for reuse of, as the toner, a powder composed mainly of a binder resin and a colorant, the external additive is adhered to the powder surface ash
And the Vickers hardness of the binder resin is 15.0 HV 0.01.
(10 g) or more, and the Vickers hardness of the toner is
A toner recycling type developing method, wherein the toner has a viscosity of 16.0 HV 0.01 (10 g) or more. 2. An electrostatic latent image formed on a surface of a photoreceptor is usable.
A toner recycling type developing apparatus for visual image of carries a developer container containing a developer including a toner, the developer contained in the developer container, its
By bringing the developer carried in close proximity to the photoreceptor
The toner is attracted to the electrostatic latent image to form a toner image.
A developer for visualizing an image, and the image forming apparatus after the toner image is transferred to a recording sheet.
Collect the toner remaining on the photoconductor and return it to the developer container.
Toner collecting means, wherein the toner is a powder mainly composed of a binder resin and a colorant.
Body with external additives attached to the surface of this powder
The binder resin has a Vickers hardness of 15.0 HV 0.01.
(10 g) or more, and the Vickers hardness of the toner is 16.0 HV 0.01.
(10 g) or more
Development device.