JP2003280259A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of effectively preventing an image carrier from being filmed with toner left after transfer in a simultaneous developing/cleaning system image forming apparatus. <P>SOLUTION: The one-component toner 7, which is used for the cleanerless simultaneous developing/cleaning system image forming apparatus, comprises the synchronous toner where the additive agent 4b sticks to a base particle 4a, an asynchronous base particle 4a' with no additive agent 4b stuck and free additive agent 4b in a coexisting state. In this case, the additive agent isolation ratio of the one-component toner 7 is set to be ≤7%. It is preferable that the additive agent isolation ratio of the one-component toner 7 is set to be ≤6% in the case of a contact electrification, especially. Then, the image carrier is prevented from being filmed with the toner left after transfer. Besides, at the contact electrification process, a contact electrifying device such as an electrifying roller coming into contact with the image carrier is prevented from being soiled. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention does not include a cleaning device for cleaning transfer residual toner on an image bearing member, but an image forming apparatus of a cleanerless simultaneous development cleaning system for cleaning the transfer residual toner at the same time as development. Belong to the technical field.

[0002]

2. Description of the Related Art Conventionally, in an apparatus for forming an image by an electrophotographic process in which charging, exposing, developing, transferring, and cleaning steps are repeated, a burden of processing waste toner generated in the cleaning step and a concomitant increase in price of consumables are caused. As a countermeasure against a short maintenance cycle or the like, an image forming apparatus of a cleanerless simultaneous development cleaning system using a reversal development method has been proposed, for example, in Japanese Patent Laid-Open No. 2001-175084.

An image forming apparatus of the cleaning-less simultaneous development type cleaning system can be easily understood by referring to the above-mentioned publication, so a detailed description thereof will be omitted.
For the time being, here is a brief explanation. In the cleanerless simultaneous development cleaning method using the reversal development method, first, the charge-removing lamp is used to make the photoconductor potential uniform. At this time, transfer residual toner adheres to the photoconductor, and the charging polarity of these toner particles is not generally constant, and positively charged particles and negatively charged particles are present. Next, the photoreceptor is uniformly negatively charged. At this time, the transfer residual toner is also corona charged at the same time, and all the particles are charged to the same negative polarity as the developing toner. Next, laser exposure is performed on the photoconductor to form an electrostatic latent image. At this time, the untransferred toner remains in both the exposed and unexposed areas. Next, the toner is attached by reversal development to the portion where the surface potential is attenuated by the exposure. The negatively charged toner is transferred to the exposed portion on the higher potential side than the developing bias to be developed, and the untransferred toner attached to the unexposed portion on the lower potential side than the developing bias is at the developing bias. It is transferred to the surface and cleaning is performed. Next, the toner on the photoconductor is transferred to the paper. Next, the distribution of the toner remaining in the image form on the photoconductor is made uniform, the light blocking effect in the exposure step is suppressed, and the cleaning at the same time as the development is facilitated. The above-mentioned publication also discloses a cleanerless simultaneous development cleaning system using a regular development method.

[0004]

By the way, the toner used in the conventional image forming apparatus of the cleaner-less simultaneous development type cleaning system is generally used in order to improve the characteristics of the toner such as fluidity or chargeability. An external additive according to the purpose of improving the toner characteristics is attached to the mother particles.

However, in such a toner, generally, the added external additive hardly adheres to the mother particles, and the free external additive released from the mother particles is often mixed in the toner. . This free external additive is usually
In the developing section, it is difficult to regulate and the charge amount is low.

If the external additive release ratio of the toner (free external additive amount / total external additive amount) is too large, after the step of transferring the toner from the image carrier to the transfer material or the intermediate transfer medium is completed. As a result, a large amount of free external additive remains on the image carrier as a transfer residue. The residual free external additive remaining after the transfer passes through the charging step of the image bearing member, so that the adhesive force to the image bearing member increases, and it becomes difficult to collect the residual external additive from the mother particles in the developing section where cleaning is performed at the same time. . Then, after the image forming apparatus is used for a long period of time, the residual free external additive remaining after transfer causes a problem of fixing the image carrier and filming of the image carrier.

In particular, in the case of non-contact development, since it is not expected that the free external additive remaining on the image bearing member will be scraped off by friction, it is more difficult to suppress the occurrence of filming on the image bearing member. Become. Further, in the case of contact development, the free external additive is likely to adhere to the charging roller, and the resin film of the external additive is gradually formed around the free external additive adhering to the charging roller as a core to lower the charging ability. Then, there is a problem that the image density cannot be obtained.

The present invention has been made in view of the above circumstances, and an object thereof is to effectively prevent filming of an image carrier due to transfer residual toner in an image forming apparatus of a cleaning simultaneous developing system. It is to provide an image forming apparatus capable of performing the same.

[0009]

In order to solve this problem, the image forming apparatus of the present invention comprises a plurality of mother particles and a large number of external additives attached to these mother particles. An image in which an image is formed by transferring a toner image obtained by developing an electrostatic latent image on an image bearing member with toner composed of particles to a transfer material or an intermediate transfer medium, and cleaning the residual toner after transfer by cleaning during development. In the forming apparatus, the external additive liberation rate of the free external additive liberated from the mother particles is set to 7% or less. Further, the invention of claim 2 is characterized in that the charging of the image bearing member by the charger is contact charging and the liberation rate of the external additive is set to 6% or less.

[0010]

In the image forming apparatus of the present invention thus constructed, the external additive release rate of the toner used in the image forming apparatus for cleaning the transfer residual toner by the simultaneous developing cleaning system is set to be 7% or less. Therefore, the amount of free external additive remaining on the image carrier when the toner is transferred from the image carrier to the transfer material or the intermediate transfer medium is reduced. This allows
When there is a possibility that the free external additive remaining on the image bearing member may pass through the charging step to increase the adhesive force to the image bearing member and be more difficult to collect from the mother particles in the simultaneous developing and cleaning section. In addition, since there is almost no free external additive remaining on the image carrier, the occurrence of filming on the image carrier is suppressed even when the image forming apparatus is used for a long period of time. In particular, in the case of non-contact development in which the scraping due to friction of the free external additive remaining on the image bearing member cannot be expected, the occurrence of filming on the image bearing member is more effectively suppressed.

Further, when a charging device such as a charging roller contacts the image bearing member to perform contact charging, the free external additive remaining after transfer easily adheres to the charging device, and the free external addition that adheres to the charging device. There is a possibility that the resin film of the external additive will be gradually formed around the agent as the core, and the charging ability will be reduced, but in the case of this contact charging,
Since the release rate of the external additive in the toner is set to 6% or less, the occurrence of filming on the image carrier can be suppressed more effectively.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing an image forming apparatus according to a non-contact charging method and a contact development simultaneous cleaning method, which is an example of an embodiment of the image forming apparatus according to the present invention.

As shown in FIG. 1, the image forming apparatus 1 of this example has an organic photoconductor 2 which is an image carrier for carrying an electrostatic latent image and a toner image, respectively, and an organic photoconductor 2 which is separated from the organic photoconductor 2. A charger 3 including a corona charger 3a for non-contact charging the organic photoconductor 2 to a uniform potential, and an electrostatic latent image on the organic photoconductor 2 is developed with a one-component toner 4 to form a toner on the organic photoconductor 2. A developing device 5 for forming an image, and a transfer device 7 for transferring the toner image on the organic photoconductor 2 to a transfer material 6 by a transfer roller 7a.
And a fixing device (not shown) for fixing the transferred image on the transfer material 6. Therefore, the image forming apparatus 1 of this example
Is a non-contact charging method and a contact development simultaneous cleaning method.

The developing device 5 carries the one-component toner 4 and conveys it to the organic photoconductor 2, and at the same time, collects the untransferred toner on the organic photoconductor 2 and a one-component toner 4 on the developing roller 5a. And a regulation blade 5c for regulating the one-component toner 4 to form a thin layer of the toner 4 having a predetermined thickness.

Further, as shown in FIG. 2, the one-component toner 4
Is composed of a large number of toner base particles 4a and a large number of particles of the external additive 4b. In that case, in the one-component toner 4, the synchronous toner in which the external additive 4b is attached to the toner mother particle 4a, and the asynchronous mother particle 4a 'in which the external additive 4b is not attached,
Asynchronous external additive (free external additive) 4b 'particles that do not adhere to the toner mother particles 4a are mixed. The synchronous external additive 4b attached to the toner base particles 4a is indicated by reference numeral "4b""in FIG. 2, and the toner base particles 4a to which the external additive 4b is attached is referred to as synchronous toner.

In the image forming apparatus 1 of this example configured as described above, the same operation as the cleanerless simultaneous development cleaning operation using the reversal developing method disclosed in the above-mentioned publication is performed. That is, first, the corona charger 3
Due to the non-contact charging of a, the organic photosensitive member 2 is charged to a uniform negative potential. At this time, transfer residual toner from the previous image formation adheres on the organic photoconductor 2, and these transfer residual toners are also corona charged at the same time, and all particles have the same negative electrode as the one-component toner 4 for development. Charged with nature.
Next, the organic photoconductor 2 is exposed by a laser or the like to form an electrostatic latent image. At this time, the untransferred toner remains in both the exposed portion and the unexposed portion. Next, the one-component toner 4 conveyed by the developing roller 5a is attached by reversal development to the portion where the surface potential is attenuated by the exposure. The negatively charged toner is transferred to the exposed portion on the higher potential side than the developing bias to be developed, and at the same time, the untransferred toner attached to the unexposed portion on the lower potential side than the developing bias is at the developing bias. 5a is transferred to the surface for cleaning. Then, the toner image on the organic photoconductor 2 is transferred to the transfer material 6. Next, the organic photoconductor 2
The distribution of the toner remaining on the image in the upper portion is made uniform, and the light blocking effect in the exposure step is suppressed, and
Simultaneous development cleaning is facilitated. It is needless to say that the cleanerless simultaneous development cleaning operation using the regular developing method disclosed in the above-mentioned publication can be performed.

By the way, the external additive release rate of the one-component toner 4 used in the image forming apparatus 1 of this example is 7%.
It is set below.

The external additive release rate of the one-component toner 4 is most appropriately determined for the toner transferred to the transfer material 6 at the time of transfer, but the external additive release rate of the one-component toner 4 on the transfer material 6 is determined. Since it is relatively difficult to obtain the rate, the developing device 5
By determining the external additive release rate of the one-component toner 4 supplied to the toner, the external additive release rate can be obtained more easily.

The amount of free external additive 4b 'of the one-component toner 4,
The external additive release rate and the slope of the synchronization straight line (synchronization distribution graph) are, for example, the particle analyzer (PT1
000) to analyze the toner mother particles 4
It can be determined easily and more accurately by analyzing the state of adhesion between a and the external additive 4b.

This toner analysis method using a particle analyzer is disclosed in detail in Japanese Patent Application Laid-Open No. 2000-047425, and since it can be understood by referring to this publication, a detailed description thereof will be omitted here, but for the time being. ,
Briefly explained.

The toner base particles 4a and the external additive 4 obtained by this toner analysis method are plotted on a diagram in which the horizontal axis represents the equivalent particle diameter of the toner base particles 4a and the vertical axis represents the external additive 4b.
When the equivalent particle diameter of each equivalent particle of b is plotted for each particle of the one-component toner 4, an equivalent particle diameter distribution chart of the toner particles is obtained. From this equivalent particle size distribution diagram, the adhesion state of the external additive 4b to the toner base particles 4a of the one-component toner 4 is analyzed. In that case, in this equivalent particle size distribution chart, a minimum of 2
One approximate line passing through the origin obtained by using the multiplication method is obtained (for details, refer to the above-mentioned publication), and the toner mother particles 4a
The adhesion state between the external additive 4b and the external additive 4b is analyzed by the slope of this approximate straight line (that is, the synchronous distribution graph) (equivalent particle diameter of the external additive 4b / equivalent particle diameter of the toner mother particles 4a). The external additive release rate is given as a percentage of the amount of the free external additive 4b 'with respect to the total amount of the external additive 4b of the one-component toner 4 obtained by the toner analysis method using the particle analyzer.

Further, in the synchronous toner in which the external additive 4b is attached to the toner base particles 4a, some of the external additives 4b are solidified as shown in FIG.
Some of them are sparsely attached to the entire surface of a, and some of the external additives 4b are almost uniformly attached to the toner mother particles 4a as shown in FIG. 3B. Now, assuming that the toner base particles 4a and the external additive 4b have the same amount in these synchronous toners, the external additive 4b shown in FIG.
The slope of the synchronization straight line (the slope of the above-mentioned approximate straight line) of the synchronization toner that is sparsely attached to the toner is relatively small, and
The external additive 4b shown in (b) has a relatively large inclination of the synchronization straight line in the synchronization toner in which the external additive 4b adheres to the toner mother particles 4a substantially uniformly. Therefore, the state of the synchronous toner can be known from the inclination of this straight line. Further, toners having the same inclination of the synchronization straight line have uniform charging characteristics, and have the same developing condition.

As the toner mother particles 4a of the one-component toner 4 used in the image forming apparatus 1 of this example, toner mother particles obtained by a pulverization method and a polymerization method (hereinafter, the former is a pulverization toner, the latter is a polymerization toner). Also referred to as 4a). As the pulverized toner 4a, at least a pigment (coloring agent) is contained in a resin binder, a release agent and a charge control agent are added in some cases, and the mixture is uniformly mixed with a Henschel mixer and then melted and kneaded with a twin-screw extruder. After cooling, a coarse pulverization-fine pulverization step is performed, and the toner mother particles obtained by the classification treatment are further externally added with external additives to obtain toner particles.

As the binder resin, known toner resins can be used, and examples thereof include polystyrene and poly-.
α-methylstyrene, chloropolystyrene, styrene-
Chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer Polymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid ester-methacrylic acid ester copolymer, styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, styrene- A styrene resin such as a vinyl methyl ether copolymer, which is a homopolymer or copolymer containing styrene or a styrene substitute, a polyester resin, an epoxy resin, a urethane modified epoxy resin, a silicone modified epoxy resin, a vinyl chloride resin, a rosin modified malein. Acid resin, phenyl tree , Polyethylene, polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, etc. Alternatively, they can be mixed and used. Particularly in the present invention, styrene-acrylic acid ester-based resin, styrene-methacrylic acid ester-based resin, and polyester resin are preferable. In the present invention, the binder resin has a glass transition temperature of 50 ° C to 75 ° C and a flow softening temperature of 10 ° C.
The range of 0 ° C to 150 ° C is preferable.

As the colorant, a known colorant for toner can be used. For example, carbon black, lamp black, magnetite, titanium black, chrome yellow, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6G, calco oil blue, quinacridone, benzidine yellow, rose bengal, malachite green lake, Quinoline yellow, C.I. I. Pigment Red 4
8: 1, C.I. I. Pigment Red 122, C.I. I.
Pigment Red 57: 1, C.I. I. Pigment Red 184, C.I. I. Pigment Yellow 12, C.I.
I. Pigment Yellow 17, C.I. I. Pigment
Yellow 97, C.I. I. Pigment Yellow 180,
C. I. Solvent Yellow 162, C.I. I. Pigment Blue 5: 1, C.I. I. Pigment Blue 1
Dyes and pigments such as 5: 3 can be used alone or in combination.

As the release agent, known release agents for toner can be used. Examples thereof include paraffin wax, microwax, microcrystalline wax, cadilla wax, carnauba wax, rice wax, montan wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax and oxidized polypropylene wax. Among them, polyethylene wax, polypropylene wax, carnauba wax, ester wax and the like are preferably used.

As the charge adjusting agent, known charge adjusting agents for toner can be used. For example, oil black, oil black BY, Bontron S-22 {produced by Orient Chemical Industry Co., Ltd.}, Bontron S-34 {produced by Orient Chemical Industry Co., Ltd.}, salicylic acid metal complex E-81 {Orient Chemical Industry Co., Ltd.) , Thioindigo pigments, sulfonylamine derivatives of copper phthalocyanine, Spiron Black TRH {produced by Hodogaya Chemical Co., Ltd.}, calixarene compounds, organic boron compounds, fluorine-containing quaternary ammonium salt compounds, monoazo metal complexes, Examples thereof include aromatic hydroxylcarboxylic acid-based metal complexes, aromatic dicarboxylic acid-based metal complexes, and polysaccharides. Among them, colorless or white ones are preferable for color toners.

The component ratio (weight ratio) in the pulverized toner 4a is 100 parts by weight of the binder resin.
The colorant is 0.5 to 15 parts by weight, preferably 1 to 10 parts by weight, and the release agent is 1 to 10 parts by weight.
Parts by weight, preferably 2.5 to 8 parts by weight, and the charge control agent is 0.1 to 7 parts by weight, preferably 0.5 to 5 parts by weight. The pulverized toner thus obtained has an average particle diameter of 5 μm to 10 μm.
m, preferably 6 μm to 9 μm.

In such a pulverized toner 4a,
For the purpose of improving the transfer efficiency, it may be spheroidized, and for that purpose, a device capable of crushing in a relatively round spherical shape in the crushing process, for example, a turbo mill known as a mechanical crusher {Kawasaki Heavy Industries ( The circularity can be up to 0.93 by using the product manufactured by K.K. Alternatively, the crushed toner is a commercially available hot air spheronizing device surfing system SFS-
The circularity can be up to 1.00 by using the 3rd type (manufactured by Nippon Pneumatic Mfg. Co., Ltd.).

The polymerization toner 4a includes suspension polymerization method and emulsion polymerization method. In the suspension polymerization method, a polymerizable monomer (monomer), a color pigment, and a release agent are further added, and if necessary, a mixture containing a dye, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives is added. The dissolved or dispersed monomer composition is added to an aqueous phase containing a suspension stabilizer (water-soluble polymer, poorly water-soluble inorganic substance) with stirring to granulate,
It can be polymerized to form colored polymerized toner particles having a desired particle size.

Further, in the emulsion polymerization method, a monomer and a releasing agent are further dispersed in water if necessary, and a polymerization initiator, an emulsifier (surfactant), etc. are dispersed in the water to carry out polymerization. Colored toner particles having a desired particle size can be formed by adding a charge control agent and an aggregating agent (electrolyte). Regarding the materials used for preparing the polymerized toner, the same materials as those for the pulverized toner described above can be used for the colorant, the release agent, the charge control agent, and the fluidity improver.

As the polymerizable monomer (monomer), a known vinyl-based monomer can be used, and examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene and p. -Methoxystyrene, p-ethylstyrene, vinyltoluene, 2,4-
Dimethylstyrene, pn-butylstyrene, p-phenylstyrene, p-chlorostyrene, divinylbenzene, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate. , Dodecyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacrylic acid Isobutyl, methacrylic acid n
-Octyl, dodecyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, cinnamic acid,
Ethylene glycol, propylene glycol, maleic anhydride, phthalic anhydride, ethylene, propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propyleneate, acrylonitrile, methacrylonitrile, vinylmethyl Ether, vinyl ethyl ether, vinyl ketone,
Examples thereof include vinyl hexyl ketone and vinyl naphthalene. Examples of the fluorine-containing monomer include 2,2
2-trifluoroethyl acrylate, 2,2,3,3
-Tetrafluoropropyl acrylate, vinylidene fluoride, ethylene trifluoride, tetrafluoroethylene, trifluoropropylene and the like can be used because the fluorine atom is effective for negative charge control.

Known emulsifiers (surfactants) can be used. For example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate, dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride. , Hexadecyltrimethylammonium bromide, dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether and the like.

As the polymerization initiator, known ones can be used. For example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, 4,4′-azobiscyanovaleric acid, t-butyl hydroperoxide, benzoyl peroxide, 2,2′-azobis-isobutyronitrile, etc. is there.

Known coagulants (electrolytes) can be used. Examples thereof include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, aluminum sulfate, iron sulfate and the like.

Even in the case of such a polymerization toner 4a,
For the purpose of improving the transfer efficiency, spheroidizing treatment may be performed. As a method for adjusting the circularity of the polymerization toner, the emulsion polymerization method is performed by controlling the temperature and time in the aggregation process of the secondary particles. The circularity can be changed freely, and the range is 0.
94 to 1.00. In addition, in the suspension polymerization method, since a spherical toner is possible, the circularity is in the range of 0.98 to 1.00. Also, in order to adjust the circularity, the toner T
Circularity is 0.94 by deforming by heating at temperature above g.
It is possible to freely adjust the value up to 0.98.

The polymerization method toner 4a can be prepared by a dispersion polymerization method other than the above-mentioned method, for example, JP-A-63-304.
It can also be produced by the method disclosed in Japanese Patent Publication No. 002. In this case, since the shape is close to a true sphere, in order to control the shape, it is possible to press the toner at a temperature higher than the Tg temperature to obtain a desired toner shape. In this way
The obtained polymerized toner has an average particle diameter of 4 μm to 9 μm, preferably 4.5 μm to 8 μm. In the present invention, the average particle diameter and circularity of toner particles and the like are values measured by FPIA2100 manufactured by Sysmex Corporation.

As the external additive 4b of the one-component toner 4, silica, titanium dioxide, alumina, magnesium fluoride, silicon carbide, boron carbide, titanium carbide, zirconium carbide, boron nitride, titanium nitride, zirconium nitride, magnetite is used. , Molybdenum disulfide, aluminum stearate, magnesium stearate, zinc stearate, calcium stearate, metal titanate, silicon metal salt, each having an average primary particle size of 1 to 50.
Those having a thickness of 0 nm, preferably 5 to 200 nm can be used. However, it is preferable to contain an element that is rarely contained in the composition of the mother particles so that it can be detected by PT-1000.

The external additives 4b are each surface-treated for hydrophobization and fluidization. In the case of negative charging treatment, the surface treatment of this external additive is carried out by chemically treating with a surface treating agent such as a silane coupling agent, a higher fatty acid, or a silicone oil, which reacts or physically adsorbs with the external additive. Done. As the surface treatment agent, for example, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, Brommethyldimethylchlorosilane, α-chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxy. Silane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,
For example, 3-diphenyltetramethyldisiloxane and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and having a hydroxyl group bonded to Si in each terminal unit are used. Moreover, these can also be used in 1 type (s) or 2 or more types of mixture. Further, in the case of the positive charging treatment, the surface treatment of the external additive is performed by chemically treating it with a coupling agent having an amino group or a surface treatment agent such as silicone oil. Furthermore, this external additive 4b is also manufactured by a general manufacturing method that has been conventionally performed.

Then, the toner mother particles 4a and the external additive 4b are respectively used to, for example, the toner mother particles 4
a and the external additive 4b are added in appropriate amounts to a known composite machine such as a Henschel mixer, a V-type blender, a reversing mixer, a high speed mixer, a cyclomix, an axial mixer, etc., and externally added to the toner mother particles 4a. The particles of the one-component toner 4 to which the particles of the agent 4b are attached are prepared.

According to the image forming apparatus 1 of this example, the external additive of the one-component toner 4 used in the image forming apparatus 1 for cleaning the transfer residual toner by the non-contact charging and the non-contact cleanerless development simultaneous cleaning system. Since the liberation rate is set to a small value of 7% or less, the liberated external additive 4b 'remaining on the organic photoconductor 2 during toner transfer from the organic photoconductor 2 to the transfer material 6 can be reduced. As a result, the free external additive 4b 'remaining on the organic photoconductor 2 passes through the charging process to increase the adhesive force to the organic photoconductor 2 and is more difficult to collect from the mother particles 4a in the developing simultaneous cleaning section. In the case where there is a possibility that this may occur, since there is almost no free external additive 4b remaining on the organic photoconductor 2, the occurrence of filming of the organic photoconductor 2 is suppressed even when the image forming apparatus 1 is used for a long period of time. can do. Particularly, in the case of non-contact development in which the scraping of the free external additive 4b ′ remaining on the organic photoconductor 2 cannot be expected, the occurrence of filming of the organic photoconductor 2 can be suppressed more effectively.

FIG. 4 is a diagram schematically showing another example of the embodiment of the present invention, which is an image forming apparatus of a non-contact charging system and a non-contact development simultaneous cleaning system.

As shown in FIG. 4, the image forming apparatus 1 of this example is different from the image forming apparatus 1 shown in FIG.
And the developing roller 5a are spaced apart from each other with a predetermined developing gap L. Therefore, the image forming apparatus 1 of this example is of the non-contact charging type and the non-contact developing simultaneous cleaning type. The external additive release rate of the one-component toner 4 used in the contact-charged image forming apparatus 1 of this example is also set to 7% or less as in the example shown in FIG. Other configurations and other effects of the image forming apparatus 1 of this example are the same as those of the example shown in FIG.

FIG. 5 is a diagram schematically showing an image forming apparatus of a contact charging type and a contact development simultaneous cleaning type, which is still another example of the embodiment of the present invention.

As shown in FIG. 5, the image forming apparatus 1 of this example is different from the image forming apparatus 1 shown in FIG. 1 in that the charger 3 is composed of a charging roller 3b. The charging roller 3b contacts the image carrier 2 to charge the image carrier 2. Therefore, the image forming apparatus 1 of this example
Is a contact charging method and a contact development simultaneous cleaning method. The external additive release rate of the one-component toner 4 used in the contact-charged image forming apparatus 1 of this example is preferably set to 6% or less in consideration of contamination of the charging roller 3b. Other configurations and other effects of the image forming apparatus 1 of this example are the same as those of the example shown in FIG.

FIG. 6 is a diagram schematically showing an image forming apparatus of a contact charging type and a non-contact development simultaneous cleaning type, which is still another example of the embodiment of the present invention.

As shown in FIG. 6, the image forming apparatus 1 of this example is different from the image forming apparatus 1 shown in FIG.
And the developing roller 5a are spaced apart from each other with a predetermined developing gap L. Therefore, the image forming apparatus 1 of this example is of a contact charging type and a non-contact development simultaneous cleaning type. Similarly to the example shown in FIG. 5, the external additive release rate of the one-component toner 4 used in the contact-charged image forming apparatus 1 of this example is also set to 6% or less in consideration of the contamination of the charging roller 3b. It is preferable. Other configurations and other effects of the image forming apparatus 1 of this example are as shown in FIG.
It is the same as the example shown in. The image forming apparatus 1 of the present invention
Is a secondary transfer type image forming apparatus 1 that primarily transfers the toner image on the image carrier 2 to an intermediate transfer medium (not shown) and transfers the primary transfer image on the intermediate transfer medium to a transfer material 6 such as paper. Can also be applied to.

Next, an embodiment of the image forming apparatus 1 of this example will be described. Experiments were carried out on the filming of the organic photoconductor 2 and the contamination of the charging roller for four examples belonging to the present invention and two comparative examples not belonging to the present invention.

The materials and the manufacturing method of the one-component toner 4 used in this experiment are the polyvalent metal compound of the polycondensation polyester of aromatic dicarboxylic acid and alkylene etherified bisphenol A in any of the examples and the comparative examples. 100 parts by weight of a 50:50 (weight ratio) mixture of partially cross-linked products, 5 parts by weight of phthalocyanine blue as a cyan pigment, 3 parts by weight of polypropylene having a melting point of 152 ° C. and a molecular weight Mw of 4000 as a releasing agent, and a charge. 2 parts by weight of salicylic acid metal complex E-81 {manufactured by Orient Chemical Industry Co., Ltd.} as a control agent is used in a Henschel mixer 20C.
Was uniformly mixed, and then kneaded with a twin-screw extruder and cooled. The cooled product was crushed by a jet mill and classified by an airflow classifier to obtain toner base particles 4a having an average particle size of 8 μm.

Further, to 100 parts by weight of the toner mother particles obtained as described above, 1.2 parts by weight of silica TG810G (manufactured by Cabot) which is an external additive 4b and treated with hexamethyldisilazane is added. Henschel mixer 20
External addition treatment was carried out with C to prepare Toner 4 of each example.

The circularity was set to 0.964. The circularity was measured by measuring the shape of toner mother particles with FPIA-2100 manufactured by Sysmec Corporation, and using this measurement value,
The circularity of the toner base particles is defined as circularity = (circumferential length of circle having the same projected area as the particles) / (projected contour length of actual particle) ≦ 1. Then, the closer the circularity is to 1, the more spherical the toner becomes.

Table 1 shows the measurement results of the charging method, the developing method, the slope of the synchronous distribution, and the external additive liberation rate in Examples and Comparative Examples.

[0053]

[Table 1]

As shown in Table 1, in the examples, the charging method and the developing method are the non-contact charging and the contact developing shown in FIG. 1, respectively, and the inclination of the one-component toner 4 is 0.504,
The external additive release rate is 6.82%, and the examples are
The charging method and the developing method are the non-contact charging and the non-contact developing shown in FIG. 4, respectively, the inclination of the one-component toner 4 is 0.504, and the external additive release rate is 6.82%. The charging method and the developing method are the contact charging and the contact developing shown in FIG. 5, respectively, the inclination of the one-component toner 4 is 0.492, and the external additive release rate is 5.86%. The charging method and the developing method are the contact charging and the non-contact developing shown in FIG. 6, respectively, and the inclination of the one-component toner 4 is 0.490 and the external additive release rate is 5.44%.

Further, in the comparative example, the charging system and the developing system are the non-contact charging and the non-contact developing shown in FIG. 4, respectively, and the inclination of the one-component toner 4 is 0.506 and the external additive release rate is 7.07. In the comparative example, the charging method and the developing method are the non-contact charging and the non-contact developing shown in FIG. 4, respectively, and the inclination of the one-component toner 4 is 0.505,
The external additive release rate is 7.54%, and the comparative example is
The charging method and the developing method are the contact charging and the non-contact developing shown in FIG. 6, respectively, and the inclination of the one-component toner 4 is 0.
498, the release rate of the external additive is 7.05%.

On the other hand, as for the developing conditions, the peripheral speed of the organic photoconductor 2 is set to 180 mm / sec, and the peripheral speed ratio between the developing roller 5a and the organic photoconductor 2 is common to all of the examples and the comparative examples. Was set to 2. Further, in the case of non-contact development, the development gap L was set to 210 μm. Further, the developing bias is set to a direct current (DC) of -200 V in common in each of the examples and the comparative examples, and in the case of non-contact development, an alternating current (AC) having a frequency of 2.0 kHz and a peak / peak voltage of 1500 V is applied to this DC. ) Was superimposed. Furthermore, the dark potential and the bright potential of the organic photoconductor 2 were set to -600V and -200V, respectively.

With respect to the evaluation method, the photoreceptor filming was evaluated as defective if the printing was performed after printing 3,000 sheets, and the solid printing caused the removal due to the filming. After 3,000 sheets of durable printing, the surface of the charging roller 3b was washed with isopropyl alcohol, and when solid printing was performed thereafter, if the change in image density was 0.1 or more, it was judged as defective.
The smaller the value, the better.

Table 1 shows the evaluation results of the photoconductor filming and the contamination of the charging roller. As shown in Table 1, with regard to the filming of the photoconductor, all of the examples and the examples were good, and all of the comparative examples and the examples were poor. Regarding the contamination of the charging roller, both the example and the example were good, and the comparative example was bad. Therefore, according to the present invention, it has been found that in an image forming apparatus that is cleaned by cleaning at the same time as development, it is possible to prevent photoreceptor filming and charging roller contamination due to transfer residual toner.

[0059]

As is apparent from the above description, according to the image forming apparatus of the present invention, the liberation rate of the external additive of the toner used in the image forming apparatus for cleaning by the simultaneous development cleaning is set to be 7% or less. Therefore, it is possible to reduce the amount of free external additive remaining on the image carrier when the toner is transferred from the image carrier to the transfer material or the intermediate transfer medium. As a result, even if the image forming apparatus is used for a long period of time, the occurrence of filming on the image carrier can be reliably suppressed. In particular, in the case of non-contact development in which the scraping due to friction of the free external additive remaining on the image bearing member cannot be expected, the occurrence of filming on the image bearing member is more effectively suppressed.

When a charging device such as a charging roller contacts the image carrier to perform contact charging, the external additive release rate of the toner is set to a small value of 6% or less, so that the filming of the image carrier is performed. It is possible to more effectively suppress the occurrence of the above-mentioned phenomenon and also to effectively prevent the charging device such as the charging roller from being soiled.

[Brief description of drawings]

FIG. 1 is a diagram schematically illustrating an image forming apparatus according to a non-contact charging method and a contact development simultaneous cleaning method, which is an example of an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing a state of attachment of an external additive to mother particles of toner.

3A and 3B show a state in which an external additive is attached to a mother particle of a toner analyzed by a particle analyzer, FIG. 3A is a diagram showing a case where an external additive is attached to the mother particle, and a slope of a synchronization straight line is small; FIG. 4 is a diagram showing a case where a slope of a synchronization straight line in which an external additive is attached to a mother particle is large.

FIG. 4 is a diagram schematically showing an image forming apparatus according to another embodiment of the present invention, which uses a non-contact charging method and a non-contact development simultaneous cleaning method.

FIG. 5 is a diagram schematically showing an image forming apparatus of a contact charging type and a contact development simultaneous cleaning type, which is still another example of the embodiment of the present invention.

FIG. 6 is a diagram schematically showing an image forming apparatus of a contact charging system and a non-contact development simultaneous cleaning system, which is still another example of the embodiment of the invention.

[Explanation of symbols]

1 ... Image forming apparatus, 2 ... Image carrier, 3 ... Charging device, 3a ...
Corona charger, 3b ... Charging roller, 4 ... One-component toner,
4a ... Mother particles, 4b ... External additive, 4a '... Asynchronous mother particles,
4b '... free external additive, 4b "... synchronous external additive, 5 ... developing device (simultaneous development cleaning system), 5a ... developing roller, 6
... transfer material, 7 ... transfer device, 7a ... transfer roller

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Rie Miyazaki             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation F term (reference) 2H005 AA08 CB13 EA10                 2H077 AA37 AC04 AC16 AD02 AD06                       AD36 EA11 EA16 GA17                 2H134 GA01 HF13 KG01 KG03 KG07                       KG08 KH17                 2H200 FA14 GA16 GA23 GA46 GA54                       GA57 GA59 GB37 HA03 HA12                       HB03 HB12 HB17 HB22

Claims (2)

[Claims] 1. An electrostatic latent image is formed on an image carrier uniformly charged by a charger, and the electrostatic latent image is formed by a large number of mother particles and a large number of external additives attached to the respective mother particles. In the image forming apparatus, an image is formed by developing with a toner composed of agent particles, and the toner image is transferred to a transfer material or an intermediate transfer medium to form an image, and the transfer residual toner is cleaned by simultaneous cleaning with development. The external additive release rate of the free external additive released from the particles is 7
The image forming apparatus is characterized by being set to less than or equal to%. 2. The image forming apparatus according to claim 1, wherein the charging of the image carrier by the charger is contact charging, and the external additive release rate is set to 6% or less. .