JP4803013B2 - Image forming method and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming method and an image forming apparatus applicable to an electrophotographic copying machine and printer.

  In recent years, the demand for energy-saving technology has been increasing as a measure to prevent global warming. In response to this demand, energy-saving technology has been emphasized in the development of electrophotographic printers and copiers. Yes.

  As an energy saving effect related to electrophotography, a low-temperature fixing toner capable of fixing at a low temperature has been proposed in order to reduce power consumption in a fixing process (fixing process) that consumes the most power (Patent Document 1).

  Although this low-temperature fixing toner can be fixed on a transfer material at a lower temperature than conventional toners, the toner itself is liable to be fused and has a disadvantage that it is inferior in heat resistance inside the apparatus. Specifically, the toner component easily adheres to the photoconductor, adheres to the surface of the photoconductor, causes toner filming, and easily causes streak-like or spotted image defects. Further, the toner adhering to the photoconductor is transferred to a peripheral member in contact with the photoconductor to cause further image defects. For example, in a contact-type charger using roller charging, toner filming is transferred to the charging roller from the surface of the photosensitive member, causing uneven charging that coincides with the cycle of the charging roller, resulting in image defects such as blurring.

In order to solve the above problems, the researchers of the present invention have studied adding a large amount of an external additive to the toner to improve the fluidity of the toner and prevent toner filming. Certainly, an improvement effect for preventing the occurrence of toner filming was obtained by using a large amount of the external additive, but a side effect due to the addition of a large amount of the external additive also occurred. That is, the amount of the external additive released from the toner increases, and the external additive itself adheres to the surface of the photoconductor in a large amount, thereby causing raindrop-like image defects.
JP 2004-157423 A

  The object of the present invention is to solve the problems of the prior art as described above. That is, the present invention is to provide an image forming method and an image forming apparatus capable of preventing toner filming on the surface of a photoreceptor and a charging roller even when a low-temperature fixing toner is used, and preventing occurrence of image defects. Another object of the present invention is to provide an image forming method and an image forming apparatus with high printing durability capable of producing a good electrophotographic image.

  Also provided is an image forming method and an image forming apparatus capable of preventing toner filming on the surface of the photoreceptor and preventing image defects such as raindrops even when a large amount of fine particle external additive is used for the low-temperature fixing toner. It is an object of the present invention to provide a high printing durability image forming method and an image forming apparatus capable of producing a good electrophotographic image.

As a result of examining the above problems in detail, the present inventors have determined that the surface of the photoconductor can be obtained by giving the organic photoconductor a characteristic that the fine particle external additive does not easily adhere even if a large amount of the fine particle external additive is used. The present invention has been achieved by finding that a good electrophotographic image can be produced in which raindrop-like image defects due to toner filming and adhesion of fine particle external additives can be prevented. That is, the present invention is achieved by having the following configuration.
(1) Uniform charging is applied to the organic photoreceptor in the charging step, an electrostatic latent image is formed in the image exposure step, the electrostatic latent image is visualized into a toner image in the developing step, and the toner image is transferred to the transfer medium. In the image forming method including the step of transferring to the surface and the cleaning step of removing the residual toner after transfer, the organic photoreceptor has at least a charge generation layer and a charge transport layer, and the charge transport layer comprises the following compound (1): A method for forming an image, comprising: at least one kind of (4) to (5), wherein the toner used in the development step contains 1.5% by mass or more and 5.0% by mass or less of a fine particle external additive.

(2) The image forming method as described in (1) above, wherein the fine particle external additive is inorganic fine particles.
(3) The image forming method as described in 1 or 2 above, wherein the inorganic fine particles contain two or more kinds of inorganic fine particles having different particle diameters.
(4) The image forming method described in (1) above, wherein the fine particle external additive contains inorganic fine particles and organic fine particles.
(5) A uniform charging is applied using a charging roller in contact with the organic photoreceptor, an electrostatic latent image is formed by an image exposure unit, and the electrostatic latent image is visualized as a toner image by a developing unit. In an image forming apparatus having a means for transferring an image to a transfer medium and a cleaning means for removing residual toner after transfer, the organic photoreceptor has at least a charge generation layer and a charge transport layer, and the charge transport layer comprises: Image formation characterized in that it contains at least one compound (1) to (4), and the toner used in the developing means contains 1.5% by mass or more and 5.0% by mass or less of a fine particle external additive. apparatus.

  By using the image forming method and the image forming apparatus of the present invention, it is possible to prevent toner filming on the surface of the photoreceptor and the charging roller, and easily occur when toner containing a large amount of fine particle external additive is used. Further, it is possible to provide a high printing durability image forming method and an image forming apparatus capable of preventing the occurrence of a raindrop-like image defect and producing a good electrophotographic image.

  Hereinafter, the present invention will be described in detail.

  In the image forming method of the present invention, a uniform charge is imparted on an organic photoreceptor in a charging step, an electrostatic latent image is formed in an image exposure step, and the electrostatic latent image is visualized into a toner image in a development step. In the image forming method including a step of transferring a toner image to a transfer medium and a cleaning step of removing residual toner after transfer, the organic photoreceptor has at least a charge generation layer and a charge transport layer, and the charge transport layer includes A fine particle external additive containing at least one of the following compounds (1) to (4) and having a toner used in the development step of 1.5% by mass or more and 5.0% by mass or less (before adding the fine particle external additive) The toner is 100% by mass as a reference).

  The image forming method of the present invention has the above-described configuration, thereby preventing toner filming on the surface of the photosensitive member and the charging member (charging roller, etc.), and using a toner containing a large amount of fine particle external additive. It is possible to provide an image forming method and an image forming apparatus with high printing durability that can prevent the occurrence of raindrop-like image defects, which are likely to occur when used, and can produce good electrophotographic images. This is particularly effective when a low-temperature fixing toner is used as the toner.

  First, the organic photoreceptor according to the present invention will be described.

  In the present invention, the organic photoconductor means an electrophotographic photoconductor configured to have an organic compound having either a charge generation function or a charge transport function essential for the configuration of the electrophotographic photoconductor, It contains all known organic electrophotographic photoreceptors such as a photoreceptor composed of a known organic charge generating material or organic charge transport material, a photoreceptor composed of a polymer complex with a charge generating function and a charge transport function.

  The layer structure of the organic photoreceptor of the present invention preferably has a charge generation layer and a charge transport layer on a conductive support, and the charge transport layer is preferably formed of a plurality of layers. Moreover, it is preferable to provide an intermediate layer between the conductive support and the charge generation layer, which can block the entry of free carriers from the support. Hereinafter, preferred configurations of the organic photoreceptor of the present invention are shown.

Conductive Support The conductive support used in the photoreceptor of the present invention may be either a sheet or a cylinder, but in order to design an image forming apparatus in a compact manner, a cylindrical conductive support is used. Is preferred.

  Cylindrical conductive support means a cylindrical support necessary for forming an endless image by rotating. Conductivity is within a range of 0.1 mm or less in straightness and 0.1 mm or less in deflection. A support is preferred. Exceeding the roundness and shake range makes it difficult to form a good image.

As the conductive material, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ωcm or less at room temperature.

  As the conductive support used in the present invention, one having an alumite film that has been sealed on the surface thereof may be used. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing treatment in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / L, the aluminum ion concentration is 1 to 10 g / L, the liquid temperature is about 20 ° C., and the applied voltage is preferably about 20 V. It is not limited. The average film thickness of the anodized film is usually 20 μm or less, particularly preferably 10 μm or less.

Intermediate Layer In the present invention, it is preferable to provide an intermediate layer that can block the entry of free carriers from the support between the conductive support and the photosensitive layer.

  In the present invention, in order to improve the adhesion between the conductive support and the photosensitive layer, or to prevent charge injection from the support, an intermediate layer (including an undercoat layer) is provided between the support and the photosensitive layer. Including) can also be provided. Examples of the material for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units. Of these subbing resins, a polyamide resin is preferable as a resin capable of reducing the increase in residual potential due to repeated use. The film thickness of the intermediate layer using these resins is preferably 0.01 to 0.5 μm.

  Examples of the intermediate layer preferably used in the present invention include an intermediate layer using a curable metal resin obtained by thermosetting an organic metal compound such as a silane coupling agent or a titanium coupling agent. As for the film thickness of the intermediate | middle layer using curable metal resin, 0.1-2 micrometers is preferable.

  An intermediate layer preferably used in the present invention includes an intermediate layer in which inorganic particles are dispersed in a binder resin. The average particle diameter of the inorganic particles is preferably 0.01 to 1 μm. In particular, an intermediate layer in which N-type semiconductive fine particles subjected to surface treatment are dispersed in a binder is preferable. For example, an intermediate layer in which titanium oxide having an average particle size of 0.01 to 1 μm, which has been surface-treated with silica / alumina treatment and a silane compound, is dispersed in a polyamide resin. The film thickness of such an intermediate layer is preferably 1 to 20 μm.

  The N-type semiconducting fine particles are fine particles having the property of using conductive carriers as electrons. That is, the property that the conductive carrier is an electron is that the N-type semiconducting fine particles are contained in an insulating binder to effectively block hole injection from the substrate, and to convert electrons from the photosensitive layer into electrons. On the other hand, it has the property which does not show blocking property.

Specific examples of the N-type semiconductive fine particles include fine particles such as titanium oxide (TiO ₂ ) and zinc oxide (ZnO). In the present invention, titanium oxide is particularly preferably used.

  The average particle diameter of the N-type semiconducting fine particles used in the present invention is preferably in the range of 10 nm to 500 nm in the number average primary particle diameter, more preferably 10 nm to 200 nm, and particularly preferably 15 nm to 50 nm. .

  The intermediate layer using N-type semiconducting fine particles whose number average primary particle size is within the above range can be finely dispersed in the layer, has sufficient potential stability, and generates black spots. Has a prevention function.

  For example, in the case of titanium oxide, the number-average primary particle size of the N-type semiconducting fine particles is magnified 10,000 times by observation with a transmission electron microscope, and 100 particles are randomly observed as primary particles. It is measured as the number average diameter.

  The shape of the N-type semiconducting fine particles used in the present invention includes dendritic, needle-like, and granular shapes. For example, in the case of titanium oxide particles, the N-type semiconductive fine particles have a crystalline form. There are anatase type, rutile type, brookite type, amorphous type, etc., any crystal type may be used, or two or more crystal types may be mixed and used. Of these, the rutile type is the best.

  The surface treatment performed on the N-type semiconducting fine particles is performed for the purpose of adjusting the N-type semiconductivity and dispersibility, and examples thereof include alumina treatment, silica treatment, zirconia treatment, and reactive organosilicon compound treatment. . Although the number of treatments may be singular or plural, for example, one of them is a plurality of surface treatments, and the last surface treatment is a surface treatment with a reactive organosilicon compound in the plurality of surface treatments. Is. In addition, at least one of the surface treatments is at least one surface treatment selected from alumina, silica, and zirconia, and finally the surface treatment of the reactive organosilicon compound is performed. It is preferable.

  Alumina treatment, silica treatment, and zirconia treatment are treatments for depositing alumina, silica, or zirconia on the surface of the N-type semiconducting fine particles. Alumina, silica, and zirconia deposited on these surfaces include alumina, silica, Zirconia hydrates are also included. The surface treatment of the reactive organosilicon compound means using a reactive organosilicon compound in the treatment liquid.

  In this way, the surface treatment of the N-type semiconductive fine particles such as titanium oxide particles was performed at least twice, so that the surface of the N-type semiconductive fine particles was uniformly coated (treated), and the surface treatment was performed. When N-type semiconductive fine particles are used for the intermediate layer, the dispersibility of the N-type semiconductive fine particles such as titanium oxide particles in the intermediate layer is good, and the photosensitivity is high and does not cause image defects such as black spots. You can get a body.

  However, N-type semiconductivity generally decreases when surface treatment is repeated. Therefore, when high N-type semiconductivity is required, anatase type or brookite type titanium oxide having high N-type semiconductivity, Adopt processing.

Photosensitive layer The photosensitive layer configuration of the organic photoreceptor of the present invention includes a laminate configuration of at least a charge generation layer (CGL) containing a charge generation material and a charge transport layer (CTL) containing a charge transport layer on a conductive substrate. To do. Hereinafter, the organic photoreceptor of the present invention will be described focusing on the layer structure of the laminated structure.

Charge generation layer Charge generation layer: The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.

  A known charge generation material (CGM) can be used as the charge generation material (CGM). For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used. Among these, the CGM that can minimize the increase in residual potential due to repeated use has a three-dimensional and potential structure that can form a stable aggregate structure among a plurality of molecules. Specifically, a phthalocyanine having a specific crystal structure. CGM of pigments and perylene pigments. For example, CGMs such as titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ° with respect to Cu—Kα rays and benzimidazole perylene having a maximum peak at 2θ of 12.4 have little deterioration due to repeated use. Potential increase can be reduced.

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.01 μm to 2 μm.

Charge Transport Layer The charge transport layer according to the present invention contains a charge transport material according to the present invention, that is, at least one of the compounds (1) to (4).

  The charge transport material according to the present invention contains at least one of the compounds (1) to (4), and together with these compounds, other charge transport materials (for example, triphenylamine derivatives, hydrazone compounds, styryl compounds). , Benzidine compounds, butadiene compounds, etc.). However, when used in combination, at least one of the compounds (1) to (4) may be used as a main charge transport material (60% or more, more preferably 70% or more by mass ratio of all charge transport materials). preferable.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  The charge transport layer may be composed of a single layer, but may be composed of two or more layers. In the case of being composed of two or more layers, it is necessary for the uppermost charge transport layer to contain at least one of the following compounds (1) to (4) in order to obtain the effects of the present invention. . The total film thickness of the charge transport layer is preferably 10 to 40 μm, particularly preferably 12 to 30 μm.

  Solvents or dispersion media used to form layers such as intermediate layers, charge generation layers, and charge transport layers include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone , Methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, Tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cello Lube, and the like. The present invention is not limited to these. These solvents may be used alone or as a mixed solvent of two or more.

Developer The toner used in the development step of the present invention contains 1.5% by mass or more and 5.0% by mass or less of the fine particle external additive. In the present invention, the fine particle external additive means fine particles added after the production of the toner particle main body. As the fine particle external additive, inorganic fine particles and organic fine particles can be used alone or in combination.

  When the fine particle external additive is contained in the toner in an amount of 1.5% by mass or more and 5.0% by mass or less and used in combination with the organic photoreceptor according to the present invention described above, Produces a good electrophotographic image by preventing toner filming on the charging roller and preventing the occurrence of raindrop-like image defects that are likely to occur when toner containing a large amount of fine particle external additive is used. An image forming method and an image forming apparatus with high printing durability can be provided.

  When the amount of the fine particle external additive (total amount) in the toner is less than 1.5% by mass, toner filming is likely to occur on the surface of the photoreceptor and the charging member, and image defects such as image blurring and white streak are likely to occur. Further, in the case of a low-temperature fixing toner (specification fixing machine having a paper temperature of about 120 ° C. or less), in a long-term copy or the like, the fluidity of the toner is likely to decrease, and the image density is likely to decrease.

  On the other hand, if the amount of the fine particle external additive in the toner is more than 5.0% by mass, the fine particle external additive is easily released from the toner surface, and the free fine particle external additive adheres to the surface of the photoreceptor or the charging member. It tends to be a raindrop-like image defect or a rough image with deteriorated sharpness. The amount of the fine particle external additive is more preferably 2.0% by mass or more and 4.5% by mass or less.

  Furthermore, the inorganic external additive (inorganic fine particle external additive) preferably contains inorganic fine particles having a number average particle diameter of 5 to 300 nm.

  What is preferably used as the material for the inorganic fine particles of 5 to 300 nm is silica, alumina, titania, zirconia and the like. These inorganic fine particles preferably have a hydrophobic surface.

  The inorganic fine particles of 5 to 300 nm are preferably added to the toner in an amount of 1.5 to 5.0% by mass, more preferably 1.5 to 4.5% by mass. If added beyond this range, there is a problem that the fine particles themselves are liberated, and the scattered particles cause contamination of the band electrode and the transfer electrode, causing image defects such as image blurring and white streaks. .

  As the inorganic external additive, it is preferable to use two or more kinds of inorganic fine particles having different particle diameters in combination. Among these, it is more preferable to use in combination with a large particle size inorganic fine particle having a number average primary particle size of 0.1 to 0.3 μm and a small particle size inorganic fine particle (5 to 40 nm inorganic inorganic fine particle). It is also preferable to use two or more different kinds of inorganic fine particles in combination. These inorganic fine particles preferably have a hydrophobic surface.

  The above-mentioned particle size of the inorganic fine particles is a number average particle size, which is magnified 2000 times by observation with a transmission electron microscope, observed 100 particles, and measured as a ferret diameter by image analysis.

  In addition, the hydrophobic treatment to the inorganic fine particles is preferably a hydrophobic treatment with a so-called coupling agent such as various titanium coupling agents and silane coupling agents, and silicone oil. Further, aluminum stearate, zinc stearate, stear Hydrophobizing treatment with a higher fatty acid metal salt such as calcium phosphate is also preferably used.

  Examples of the organic fine particles include a styrene polymer, an acrylic polymer, a styrene / acrylic copolymer, the above cross-linked resin, a benzoguanamine, a melamine resin, and the like, and a mixture thereof may be used. The polymerizable monomer (monomer) which is a constituent material of the polymer and resin will be described.

  Examples of the styrene monomer include styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, 2,5. -Dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, 2,4,5-trimethylstyrene, 2,4,6-trimethylstyrene, pn-butylstyrene, pt-butylstyrene, Examples include pn-hexyl styrene, pn-octyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichloro styrene, among others. Styrene is preferably used. These styrene monomers may be used alone or in combination of two or more.

  Examples of the acrylic monomer include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate, acrylic acid, methacrylic acid, acrylonitrile, and acrylamide. Of these, methyl methacrylate is preferably used. These acrylic monomers may be used alone or in combination of two or more.

  Examples of the crosslinkable monomer that increases the degree of crosslinking include divinylbenzene, divinyltoluene, ethylene glycol di (meth) acrylate, ethylene oxide di (meth) acrylate, tetraethylene oxide di (meth) acrylate, and 1,6-hexanediol di (meta). ) Acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolpropane tri (meth) acrylate, tetramethylolpropane tetra (meth) acrylate, etc. It is done. Monomers having two or more ethylenically unsaturated groups in these molecules may be used alone or in combination of two or more.

<Number average particle diameter of organic fine particles>
The number average particle diameter of the organic fine particles is preferably 50 to 200 nm, and more preferably 70 to 100 nm. If it is less than 50 nm, it is buried in the toner surface, and it is difficult to maintain the transfer efficiency over a long period of time. On the other hand, if it exceeds 200 nm, it is difficult to hold on the toner surface. The degree of crosslinking is 80% or more, and more preferably 90% or more. The number average particle diameter of the organic fine particles is specifically measured by the following method.

  Take a 30,000 times photograph with a scanning electron microscope, and capture the photograph image with a scanner. The image processing analyzer LUZEX AP (manufactured by Nireco) binarizes the organic fine particles present on the toner surface of the photographic image, calculates the horizontal ferret diameter for 100 organic fine particles, and averages the values. Is the number average particle size. When the number average primary particle diameter of the organic fine particles is small and exists as an aggregate on the toner surface, the particle diameter of the primary particles forming the aggregate is measured.

  The addition amount of the organic fine particles depends on the resin particle diameter, but is generally 0.5 to 3.0% by mass. By setting the content to 0.5 to 3.0% by mass, the transfer efficiency is maintained over a long period of time, and the retention performance on the toner surface is also improved, so that contamination of the photoreceptor and the charging member can be further suppressed. Because.

  The organic fine particles are preferably used in combination with inorganic fine particles to constitute the total amount of the fine particle external additive of the present invention. When the organic fine particles are used alone, it is difficult to maintain developability and transfer efficiency over a long period of time, and the image density and the like tend to decrease.

  As a method for adding the fine particle external additive to the toner, various known mixing devices such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer can be used.

The toner of the present invention is premised on that toner base particles (also referred to as colored particles) can be formed before adding the fine particle external additive. The colored particles are formed of a colorant (pigment, dye, etc.), a release agent, a binder, and the like, and can be prepared by a pulverization method or a polymerization method. The toner of the present invention is a polymerized toner prepared by a polymerization method. Is more preferable for forming a color image with good sharpness and color reproducibility.
"toner"
The toner physical properties and constituent materials according to the present invention will be described below.

<Glass transition temperature of toner>
The glass transition temperature of the toner can be measured using a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer) or a TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer).

  As a measurement procedure, 4.5 to 5.0 mg of toner is precisely weighed to two decimal places, enclosed in an aluminum pan (KITNO.0219-0041), and set in a DSC-7 sample holder. The reference used an empty aluminum pan. The measurement conditions were a measurement temperature of 0 to 200 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. Analysis was performed based on the data in Heat.

  The glass transition temperature draws an extension of the baseline before the rise of the first endothermic peak and a tangent line indicating the maximum slope between the rise of the first peak and the peak apex, and the intersection is taken as the glass transition point. Show.

<Average circularity of colored particles>
The colored particles refer to toner base particles containing a binder resin, a colorant, and a release agent before attaching the fine particle external additive. The circularity of the colored particles is a value measured using “FPIA-2100” (manufactured by Sysmex). Specifically, after the toner is blended with an aqueous solution containing a surfactant and subjected to ultrasonic dispersion for 1 minute and dispersed, the number of detected HPFs in the measurement condition HPF (high magnification imaging) mode using “FPIA-2100”. Measurement is performed at an appropriate concentration of 3000 to 10,000. Within this range, reproducible identical measurement values can be obtained. The circularity defined by the following formula was measured.

Circularity = (perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)
The average circularity is a value calculated by adding the circularity of each particle and dividing by the total number of particles. Incidentally, in order not to collect data of the fine particle external additive detached from the toner, the circularity is measured by measuring particles having a number reference particle diameter of 2 μm or more.

<Binder resin>
When the toner particles constituting the toner of the present invention are produced by a pulverization method, a dissolution suspension method, or the like, a styrene resin, (meth) acrylic resin, styrene- (meta) is used as a binder resin constituting the toner. ) Known vinyl resins such as acrylic copolymer resins and olefin resins, polyester resins, polyamide resins, carbonate resins, polyethers, polyvinyl acetate resins, polysulfones, epoxy resins, polyurethane resins, urea resins, etc. These various resins can be used. These can be used alone or in combination of two or more.

  In addition, when the toner particles constituting the toner of the present invention are produced by a suspension polymerization method, a miniemulsion polymerization aggregation method, an emulsion polymerization aggregation method, or the like, a polymerizable single amount for obtaining each resin constituting the toner Examples of the body include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2 , 4-dimethylstyrene, pt-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, etc. Or styrene styrene derivative; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, ethyl methacrylate Methacrylic acid such as propyl, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate Ester derivatives; methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate Acrylate derivatives such as phenyl acrylate; olefins such as ethylene, propylene, isobutylene; vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinyl Vinyl halides such as vinylidene fluoride; vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone Vinyl ketones; N-vinyl compounds such as N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone; vinyl compounds such as vinylnaphthalene and vinylpyridine; acrylic acid or methacrylic such as acrylonitrile, methacrylonitrile, acrylamide Examples thereof include vinyl monomers such as acid derivatives. These vinyl monomers can be used alone or in combination of two or more.

  Moreover, it is preferable to use combining what has an ionic dissociation group as a polymerizable monomer. The polymerizable monomer having an ionic dissociation group has, for example, a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group, and specifically includes acrylic acid, methacrylic acid, Maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl And methacrylate and 3-chloro-2-acid phosphooxypropyl methacrylate.

  Furthermore, as a polymerizable monomer, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol A binder resin having a crosslinked structure can also be obtained using polyfunctional vinyls such as diacrylate.

<Chain transfer agent>
In order to adjust the molecular weight of the resin, a commonly used chain transfer agent can be used. The chain transfer agent used is not particularly limited. For example, mercaptans such as octyl mercaptan, dodecyl mercaptan, t-dodecyl mercaptan, mercaptopropionate such as n-octyl-3-mercaptopropionate, terpinolene, Carbon tetrabromide and α-methylstyrene dimer are used.

<Radical polymerization initiator>
The radical polymerization initiator used in the present invention can be appropriately used as long as it is water-soluble. For example, persulfates such as potassium persulfate and ammonium persulfate, azo compounds such as 4,4'-azobis-4-cyanovaleric acid and its salts, 2,2'-azobis (2-amidinopropane) salts, peroxides Compounds and the like.

  Furthermore, you may use the said radical polymerization initiator as a redox-type initiator combined with the reducing agent as needed. By using a redox initiator, the polymerization activity is increased, the polymerization temperature can be lowered, and the polymerization time can be shortened.

<Surfactant>
The surfactant that can be used when emulsion polymerization is performed using the radical polymerizable monomer is not particularly limited, but the following ionic surfactants are preferably used.

  Examples of ionic surfactants include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, stearic acid) Potassium, calcium oleate), and the like.

  Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester Polymerization may be carried out in combination with the ionic surfactant described above as required.

  In the present invention, these are mainly used as an emulsifier at the time of emulsion polymerization, but may be used for other processes or purposes, for example, as a dispersing agent for associated particles.

<Colorant>
As the colorant used in the present invention, all known dyes and pigments can be used. Specifically, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium Yellow, yellow iron oxide, ocher, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, permanent yellow (NCG), Vulcan fast yellow (5G, R), tart Rajn Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Permanent Red 4R, Para Red, Faise Red, Parachlor Ortho Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brillia Tokarmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Torujin 5B Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red , Pyrazolone red, polyazo red, chrome vermilion, benzidine orange, perinone orange, oil orange, Baltic Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine Blue, Bituminous Blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, anthraquinone green, titanium oxide, ritbon and mixtures thereof can be used. As for content, 1-20 mass parts is preferable with respect to 100 mass parts of resin (binder resin).

<Release agent>
In the present invention, it is preferable that a release agent (hereinafter also referred to as wax) is contained in the toner in order to impart appropriate release properties to the toner and prevent the occurrence of offset. The mold release agent preferably has a melting point of 40 to 150 ° C, more preferably 50 to 110 ° C.

  By having a melting point within the above range, it has been confirmed that good fixability can be obtained and good offset resistance and durability can be obtained even when the fixing temperature is set to a low temperature.

  The melting point of the release agent can be determined by differential scanning calorimetry (DSC). That is, the melting peak value when a sample of several mg is ripened at a constant rate of temperature rise, for example, (10 ° C./min) is defined as the melting point.

  Examples of the release agent that can be used in the present invention include solid paraffin wax, micro wax, rice wax, fatty acid amide wax, fatty acid wax, aliphatic monoketone, fatty acid metal salt wax, and fatty acid ester wax. Partially saponified fatty acid ester wax, silicon varnish, higher alcohol and carnauba wax are preferably used.

  In the present invention, ester compounds represented by the following general formula are particularly preferred.

R _1- (OCO-R ₂ ) n
In formula, n is an integer of 1-4, Preferably it is 2-4, More preferably, it is 3-4, More preferably, it is 4. R ₁ and R ₂ each represents a hydrocarbon group that may have a substituent. R ₁ has 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, and more preferably 2 to 5 carbon atoms. R ₂ has 1 to 40 carbon atoms, preferably 16 to 30 carbon atoms, and more preferably 18 to 26 carbon atoms.

  In the present invention, the toner may be formed using a dispersion obtained by heating and stirring in an aqueous medium using a surfactant or a dispersant described later as a release agent. In this case, for example, it is possible to prepare a wax emulsion prepared by emulsifying a release agent, and add it together with the colorant dispersion when the resin particles are aggregated.

<Charge control agent>
The toner of the present invention may contain a charge control agent as necessary. As the charge control agent, all known ones can be used. For example, fluorine activators, salicylic acid metal salts, metal salts of salicylic acid derivatives, etc., specifically, nigrosine dye Bontron 03, quaternary ammonium salt Bontron P-51, azotron metal complex salt Bontron S-34, oxynaphthoic acid metal complex E-82, salicylic acid metal complex E-84, phenolic condensate E-89 (above, Orient Chemical Industry) TP-302, TP-415 of quaternary ammonium salt molybdenum complex (above, manufactured by Hodogaya Chemical Co., Ltd.), copy charge PSY VP2038 of quaternary ammonium salt, copy blue PR of triphenylmethane derivative, class Copy charge of ammonium salt NEGVP2036, copy charge NX VP434 (Manufactured by Kist), LRA-901, LR-147 (manufactured by Nippon Carlit Co., Ltd.) which is a boron complex, and other high molecular compounds having a functional group such as a sulfonic acid group, a carboxyl group, and a quaternary ammonium salt. Among these, azo metal complex compounds are preferable, and for example, those disclosed in paragraphs 0009 to 0012 of JP-A-2002-351150 are preferably used.

  In the present invention, the amount of charge control agent used is determined uniquely by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is uniquely limited. Although it is not a thing, Preferably it is used in 0.1-2 mass parts with respect to 100 mass parts of binder resin. Preferably the range of 0.2-5 mass parts is good.

  In the present invention, a charge control agent is preferably contained in the vicinity of the toner surface. That is, by containing the toner in the vicinity of the toner surface, it is possible to effectively impart chargeability to the toner and to ensure that the toner has fluidity by containing the charge control agent so as not to be exposed on the toner surface.

  As a specific content method, for example, there is a method of controlling the amount of the charge control agent added to the resin particles constituting the toner. That is, a method in which a large amount of charge control agent is added to the resin particles constituting the vicinity of the toner surface and the resin particles are aggregated so that the toner surface is formed with resin particles to which no charge control agent is added, An example is a method in which resin particles containing a control agent are aggregated and then encapsulated with a resin component not containing a charge control agent on the surface of the aggregated particles.

  As a method of incorporating the resin particles into the resin particles, when the dispersion diameter is kneaded with the binder resin and the dispersion diameter is adjusted or released, it may be added to the aqueous phase side and incorporated into the toner during the aggregation process or drying process.

<Toner manufacturing method>
The toner production method is not particularly limited as long as a toner satisfying the claims can be obtained. For example, suspension polymerization method, emulsion polymerization aggregation method, miniemulsion polymerization aggregation method, dispersion polymerization method, dissolution suspension method, Examples thereof include a melting method and a kneading and pulverizing method. Among these, the emulsion polymerization aggregation method and the miniemulsion polymerization aggregation method are preferably used because the average circularity of the colored particles can be easily controlled.

  Below, an example of miniemulsion polymerization / emulsion polymerization and an aggregation method is demonstrated.

(1) Dissolution / dispersion step of dissolving or dispersing the release agent in the radical polymerizable monomer (2) Polymerization step for preparing a dispersion of resin particles A having a hydrophilic resin and a hydrophobic resin (3) ) Aggregation step of aggregating resin particles and colorant particles in an aqueous medium to obtain aggregated particles (4) The aggregated aggregated particles are fused and aged by thermal energy, and a hydrophilic resin is applied to the surface of the toner base. An agglomeration step in which a hydrophobic resin is oriented inside to produce a toner base having a core / shell structure, and resin particles B are added during the growth process of the resin particles A, and after agglomeration is continued, agglomeration step (5) (6) Cooling step for cooling the dispersion of the toner base (7) Solid-liquid separation of the toner base from the cooled dispersion of the toner base And the concerned Cleaning step for removing surfactant from toner base (8) Drying step for drying washed toner base (9) Step for adding external fine particle additive to dried toner base Explained.

(Dissolution / dispersion process)
This step is a step of preparing a radical polymerizable monomer solution of the release agent by dissolving or dispersing the release agent in the radical polymerizable monomer.

(Polymerization process)
In a preferred example of this polymerization process, a radically polymerizable monomer solution in which a release agent is dissolved or dispersed in an aqueous medium containing a surfactant is added, and mechanical energy is applied to form droplets. Then, the polymerization reaction is advanced in the droplets by radicals from the water-soluble radical polymerization initiator. In addition, you may add the resin particle as a core particle in the said aqueous medium, and you may perform several steps of polymerization reaction.

  By this polymerization step, resin particles having a release agent, a hydrophilic resin, and a hydrophobic resin are obtained. Such resin particles may be colored particles or non-colored particles. The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. Further, when using resin particles that are not colored, in the fusing step described later, the dispersion of the colorant particles is added to the dispersion of the resin particles to fuse the resin particles and the colorant particles. Thus, the toner base can be obtained.

(Aggregation / fusion process)
A salting-out agent composed of an alkali metal salt or an alkaline earth metal salt is added as a flocculant having a critical aggregation concentration or more in water containing resin particles and, if necessary, colorant particles to form aggregated particles. . In the aggregating step, release agent particles, charge control agents, internal additive particles such as resin particles having different thermal characteristics, and the like can be aggregated together with the resin particles and the colorant particles.

  Specifically, the aggregation of the resin particles A is started, and particle growth is advanced to a target particle size. For example, when a toner having a median particle size (D50) of 6 μm on a volume basis is produced, aggregation is advanced until the particle size of the aggregated particles A grows to 30 to 70% of the toner particle size. Add the dispersion. The resin particles B preferably have a Tg higher than that of the resin particles A, and the addition amount of the resin particles B is preferably 10 to 80% by mass with respect to the resin particles A.

  After the dispersion of resin particles B is added, aggregation is further advanced and the particles are grown to the final particle size. After completion of the aggregation, the resin particles B are taken into the aggregate of the resin particles A.

  In this step, if a hydrophilic resin and a hydrophobic resin are present in the resin particle A, the hydrophilic resin is oriented on the surface of the particle to form a toner base having a core-shell structure. It can be done.

(Aging process)
Aging means preparing the aggregated and fused toner to a proper circularity. Aging is preferably performed by thermal energy (heating).

(Cooling process)
This step is a step of cooling the toner base dispersion. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

(Solid-liquid separation and washing process)
In this solid-liquid separation / washing step, a solid-liquid separation process for solid-liquid separation of the toner base from the dispersion of the toner base cooled to a predetermined temperature in the above-described step, and a solid-liquid separated toner cake (in a wet state) A cleaning process is performed to remove deposits such as a surfactant and a salting-out agent from an aggregate obtained by agglomerating a toner base in a cake form. The filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.

(Drying process)
This step is a step of drying the washed toner cake to obtain a dried toner base. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The moisture content of the dried toner base is preferably 5% by mass or less, and more preferably 2% by mass or less. In addition, when the toner bases subjected to the drying treatment are aggregated with a weak interparticle attractive force, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

(External treatment process)
This step is a step of preparing a toner by mixing the dried toner base with a fine particle external additive as necessary. As a mixing device for the fine particle external additive, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

<Developer>
The toner according to the present invention can be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to.

  Further, it can be mixed with a carrier and used as a two-component developer. As the carrier, conventionally known magnetic particles such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Ferrite particles are particularly preferable. The particle diameter of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm.

  The particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The coating resin is not particularly limited. For example, an olefin resin, a styrene resin, a styrene-acrylic resin, a silicon resin, an ester resin, a fluorine-containing polymer resin, or the like is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to. Among these, a coat carrier coated with a styrene-acrylic resin is more preferable because it can prevent the external additive from being detached and can ensure durability.

  Next, an image forming apparatus using the image forming method of the present invention will be described.

  FIG. 1 is a schematic cross-sectional view of an image forming apparatus 1 using a contact charging method according to the present invention. The image forming apparatus 1 includes a photosensitive cartridge 2, a developing cartridge 3, an exposure device 4 that emits a laser beam modulated based on an image signal from the outside while deflecting, a paper feeding device 5 that supplies recording paper, A transfer roller 6, a fixing device 7, a paper discharge tray 8, and a cleaning device 9 using a cleaning blade are disposed.

  The photoconductor cartridge 2 includes a photoconductor 21 formed by forming a thin film layer of an organic photoconductive material on the outer peripheral surface of a cylindrical body, a charging brush 22 and the like. The developing cartridge 3 includes a developing sleeve (not shown), a stirring roller, and a toner tank in which toner and a carrier are accommodated. A developing bias is applied to the developing sleeve from a developing power source (not shown). Both cartridges are closed when inserted into the image forming apparatus 1 in order to prevent problems caused by mechanical contact when the cartridge is attached to or detached from the image forming apparatus 1, and are removed from the image forming apparatus 1. A protective cover (not shown) that is sometimes opened is provided.

  Since the image forming process is well known, only a brief description will be given below. First, the surface of the photoreceptor 21 is uniformly charged with a predetermined voltage by the charging brush 22. The exposure device 4 generates a modulated laser beam (indicated by a broken arrow in the figure), deflects the laser beam by a polygon mirror (not shown), deflects and scans the surface of the photosensitive member 21, and applies it to the charged surface. The electrostatic latent images corresponding to the image information are sequentially formed. The toner in the toner tank is stirred by a stirring roller and then supplied onto the developing sleeve to form a toner image corresponding to the electrostatic latent image at a portion facing the photoreceptor 21. At the same time, residual toner present in a portion (non-image portion) that has not been exposed on the surface of the photoreceptor 21 is collected by the cleaning device 9 using a cleaning blade. On the other hand, the toner image is electrostatically transferred onto the recording paper by the transfer roller 6 disposed facing the photoconductor 21. Note that the recording paper is conveyed from the paper feeding device 5 along a conveyance path indicated by a solid line arrow in the drawing. Next, the recording paper is conveyed to the fixing device 7 where the unfixed toner image is heat-fixed on the recording paper. Finally, the recording paper on which a desired image is formed is discharged from the paper discharge tray 8. By repeating the above-described series of processes, a large amount of original can be duplicated at high speed.

  The charging brush mechanically agitates the residual toner sent to the contact portion with the photoconductor by the rotation of the photoconductor, and diffuses it on the surface of the photoconductor until it becomes unreadable. The charging brush electrostatically adsorbs and collects residual toner having the opposite polarity (reverse polarity) to the charging polarity of the photoconductor, and charges it to the same polarity (regular polarity) as the charging polarity of the photoconductor. Discharge onto the surface of the photoreceptor.

  FIG. 2 is a schematic cross-sectional view of a photosensitive cartridge 2 that is detachable from the image forming apparatus 1. The photosensitive member cartridge 2 includes a protective member 28 with a protective cover, a photosensitive member 21 as an image carrier, a charging brush 22 disposed around the photosensitive member 21, and a power source for applying a predetermined voltage to the charging brush 22. The connecting member 23, the pre-charge film 24, the charge leveling members (sponge-like charging members) 25 and 26, and the power source connecting member 27 are accommodated.

  The photosensitive member 21 is rotated in the direction of the arrow in the drawing by a driving device (not shown). The charging brush 22 is obtained by implanting conductive yarn made of hairy fibers on a brush support. The charging brush 22 is in contact with the surface of the photosensitive member 21 and is rotated in the same direction as the rotational direction of the photosensitive member 21 in the direction of the arrow in the drawing, that is, in the contact portion with the photosensitive member 21 by a driving device (not shown). . At the time of image formation, a voltage is applied to the charging brush 22 from a charging power source (not shown), whereby the surface of the photoreceptor 21 is uniformly charged to a predetermined polarity. On the other hand, at the time of non-image formation, a voltage having a polarity opposite to that at the time of image formation is applied to the charging brush 22 from the charging power source. The charging polarity of the toner is the same as the polarity of the charging voltage at the time of image formation. Therefore, at the time of non-image formation, the toner accumulated in the charging brush 22 can be ejected onto the photoreceptor 21 by electrostatic repulsion.

  The precharge film 24 and the charge leveling members 25 and 26 are arranged for the purpose of compensating for uneven charging due to the charging brush 22.

  A charging roller may be used instead of the charging brush shown in FIGS. FIG. 3 is a sectional view showing the configuration of the charging roller.

  As shown in FIG. 3, the charging roller 22R comprises a cored bar 22a and a rubber layer such as chloroprene rubber, urethane rubber, silicone rubber or the like, which is a conductive elastic member provided on the outer periphery thereof, or a sponge layer 22b thereof. Preferably, the outermost layer is configured by providing a protective layer 22c made of a releasable fluorine-based resin or silicone resin layer having a thickness of 0.01 to 1 μm.

  The charging roller is preferably brought into contact with the photoreceptor 21 with a pressure contact force of 10 to 100 g / cm. The rotation of the charging roller is preferably 1 to 8 times the peripheral speed of the photosensitive drum 21.

  FIG. 4 is a cross-sectional configuration diagram of a color image forming apparatus using the organic photoreceptor of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 41 and a fixing means 50. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  An image forming unit 10Y that forms a yellow image includes a charging unit 22Y, an exposure unit 30Y, a developing unit 23Y, and a primary transfer unit disposed around a drum-shaped photoconductor 21Y as a first image carrier. A primary transfer roller 5Y and a cleaning means 6Y are provided. The image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 21M as a first image carrier, a charging unit 22M, an exposure unit 30M, a developing unit 23M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photosensitive member 21C as a first image carrier, a charging unit 22C, an exposure unit 30C, a developing unit 23C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photosensitive member 21Bk as a first image carrier, a charging unit (brush charging) 22Bk, an exposure unit 30Bk, a developing unit 23Bk, and a primary transfer roller as a primary transfer unit. 5Bk and cleaning means 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 22Y, 22M, 22C, and 22Bk that rotate around the photosensitive drums 21Y, 21M, 21C, and 21Bk, and image exposure means 30Y, 30M, 30C and 30Bk, rotating developing means 23Y, 23M, 23C and 23Bk, and cleaning means 5Y, 5M, 5C and 5Bk for cleaning the photosensitive drums 21Y, 21M, 21C and 21Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of the toner images formed on the photoreceptors 21Y, 21M, 21C, and 21Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y includes a charging unit 22Y (hereinafter simply referred to as a charging unit 22Y or a charger 22Y), an exposure unit 30Y, a developing unit 23Y, and a cleaning unit 5Y (around a photosensitive drum 21Y as an image forming body). Hereinafter, the cleaning unit 5Y or the cleaning blade 5Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 21Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 21Y, the charging unit 22Y, the developing unit 23Y, and the cleaning unit 5Y are provided so as to be integrated.

  The charging unit 22Y is a unit that applies a uniform potential to the photosensitive drum 21Y. In the present embodiment, a corona discharge type charger 22Y is used for the photosensitive drum 21Y.

  The image exposure unit 30Y performs exposure based on the image signal (yellow) on the photosensitive drum 21Y given a uniform potential by the charger 22Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 30Y, the exposure means 30Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 21Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A sheet P as a recording material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the sheet cassette 40 is fed by a sheet feeding means 41 and includes a plurality of intermediate rollers. After passing through 42A, 42B, 42C, 42D and the registration roller 43, it is conveyed to the secondary transfer roller 5A as the secondary transfer means, and is secondarily transferred onto the paper P, and the color images are collectively transferred. The paper P on which the color image has been transferred is fixed by the fixing unit 50, is sandwiched between the paper discharge rollers 45, and is placed on a paper discharge tray 46 outside the apparatus.

  On the other hand, after the color image is transferred onto the sheet P by the secondary transfer roller 5A as the secondary transfer unit, the residual toner is removed by the cleaning unit 6A from the endless belt-shaped intermediate transfer body 70 from which the sheet P is separated by curvature.

  During the image forming process, the primary transfer roller 5Bk is always in pressure contact with the photoreceptor 21Bk. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 21Y, 21M, and 21C, respectively, only during color image formation.

  The secondary transfer roller 5A comes into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the sheet P passes through the secondary transfer roller 5A and secondary transfer is performed.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is arranged on the left side of the photoreceptors 21Y, 21M, 21C, 21Bk in the figure. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6A. Consists of.

  Although the image forming apparatus is a contact charging type image forming apparatus, the same effect can be obtained by using a non-contact type scorotron charger as the charging means. Is equally applicable. The exposure light source may also be a light source other than a laser, such as an LED light source.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In the following text, “part” means “part by mass”.

Production of Photoreceptor 1 Photoreceptor 1 was produced as follows.

Intermediate layer The following intermediate layer coating solution is applied by dip coating onto a washed cylindrical aluminum substrate having a diameter of 30 mm (10 points surface roughness Rz: 0.81 μm by cutting), and 120 ° C. for 30 minutes. And an intermediate layer having a dry film thickness of 5 μm was formed.

  The following intermediate layer dispersion is diluted twice with the same mixed solvent, and is allowed to stand overnight and then filtered (filter; rigesh mesh filter made by Nippon Pole Co., Ltd., nominal filtration accuracy: 5 microns, pressure: 50 kPa). Produced.

(Preparation of intermediate layer dispersion)
Binder resin: (Polyamide) 1 part Rutile titanium oxide (primary particle size 35 nm; titanium oxide pigment prepared by surface treatment with dimethylpolysiloxane having a hydroxyl group at the terminal and having a hydrophobization degree of 33) 5.6 parts Ethanol / n-Propyl alcohol / THF (= 45/20/30 mass ratio) 10 parts The above components were mixed and dispersed in a batch system for 10 hours using a sand mill disperser to prepare an intermediate layer dispersion.

Charge generation layer: CGL
Charge generation material (CGM): oxytitanyl phthalocyanine (a titanyl phthalosine pigment having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum by Cu-Kα characteristic X-ray) 24 parts polyvinyl butyral resin “S-LEC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 2-butanone / cyclohexanone = 4/1 (v / v) 300 parts The above composition is mixed, dispersed using a sand mill, and charged. A generation layer coating solution was prepared. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.5 μm on the intermediate layer.

Charge transport layer (CTL)
Charge transport material (CTM-1: Compound (1)) 225 parts Polycarbonate (Z300: Mitsubishi Gas Chemical) 300 parts Dichloromethane 2000 parts Silicon oil (KF-54: Shin-Etsu Chemical) 1 part is mixed and dissolved. Thus, a charge transport layer coating solution 1 was prepared. This coating solution was applied onto the charge generation layer by a dip coating method and dried at 110 ° C. for 70 minutes to form a charge transport layer having a dry film thickness of 23.0 μm.

Production of photoconductors 2 to 7 Photoconductors 2 to 7 were produced in the same manner as photoconductor 1 except that the type of charge transport material in the charge transport layer was changed as shown in Table 1 in the production of photoconductor 1.

  CTMR-1 in Table 1 represents a charge transport material having the following structure.

  A toner used in the present invention was prepared as follows.

(Preparation of colored particles)
<< Preparation of colored particles 1 >>
(Production of resin particles A)
First stage polymerization Into a 5 L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device, 8 g of sodium dodecyl sulfate was charged with 3 L of ion-exchanged water, and stirred while stirring at a rate of 230 rpm under a nitrogen stream. The temperature was raised to 80 ° C. After heating, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the liquid temperature was again 80 ° C., the following monomer mixture was added dropwise over 1 hour, and then heated at 80 ° C. for 2 hours. Polymerization was performed by stirring to prepare resin particles. This is referred to as “resin particles (1H)”.

Styrene 480g
n-Butyl acrylate 250g
Methacrylic acid 68.0g
n-Octanethiol 16.0g
Second stage polymerization A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device was charged with a solution prepared by dissolving 7 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 800 ml of ion-exchanged water. After heating to ℃, 260 g of the resin particles (1H) and a solution prepared by dissolving the following monomer solution at 90 ℃ were added, and a mechanical disperser CLEARMIX (M Technique Co., Ltd.) having a circulation path was added. ) To prepare a dispersion containing emulsified particles (oil droplets).

223 g of styrene
142g of n-butyl acrylate
n-Octanethiol 1.5g
190g of polyethylene wax (melting point 70 ° C)
Next, an initiator solution prepared by dissolving 6 g of potassium persulfate in 200 ml of ion-exchanged water is added to this dispersion, and this system is heated and stirred at 82 ° C. for 1 hour to obtain resin particles. It was. This is referred to as “resin particles (1HM)”.

Third stage polymerization Further, a solution prepared by dissolving 11 g of potassium persulfate in 400 ml of ion-exchanged water was added, and under a temperature condition of 82 ° C,
405 g of styrene
162 g of n-butyl acrylate
Methacrylic acid 33g
n-Octanethiol 8g
A monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin particles. This is designated as “resin particle A”.

  A part of the resin particles A were collected and measured after washing and drying, and Tg was 21 ° C.

(Production of resin particles B)
Into a 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction device, 2.3 g of sodium dodecyl sulfate was charged with 3 L of ion-exchanged water, and the internal temperature was adjusted while stirring at a stirring speed of 230 rpm under a nitrogen stream. The temperature was raised to 80 ° C. After heating, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the liquid temperature was again 80 ° C., the following monomer mixture was added dropwise over 1 hour, and then heated at 80 ° C. for 2 hours. Polymerization was performed by stirring to prepare resin particles. This is a dispersion of “resin particles B”.

Styrene 520g
210g of n-butyl acrylate
Methacrylic acid 68.0g
n-Octanethiol 16.0g
A part of the dispersion of resin particles B was collected, measured after washing and drying, and Tg was 48 ° C.

(Preparation of colorant dispersion 1)
90 g of sodium dodecyl sulfate was dissolved in 1600 ml of ion-exchanged water with stirring. While stirring this solution, 420 g of Legal 330R (Cabot carbon black) was gradually added, and then dispersed using a stirrer “CLEAMIX” (M Technique Co., Ltd.) to obtain a colorant. A dispersion of particles was prepared. This is designated as “colorant dispersion 1”. The particle diameter of the colorant particles in this colorant dispersion liquid 1 was 110 nm as measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

(Aggregation / fusion process)
In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 300 g of resin particles A in terms of solid content, 1400 g of ion-exchanged water, 120 g of “colorant dispersion 1”, polyoxy A solution prepared by dissolving 3 g of ethylene (2) sodium dodecyl ether sulfate in 120 ml of ion-exchanged water was added and the liquid temperature was adjusted to 30 ° C., and then the pH was adjusted to 10 by adding a 5 M aqueous sodium hydroxide solution. Next, an aqueous solution in which 35 g of magnesium chloride was dissolved in 35 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 90 ° C. In this state, the particle size of the associated particles was measured with “Coulter Multisizer 3”, and when the median diameter on the volume basis became 3.1 μm, 260 g of the dispersion of resin particles B was added, and further the particle growth reaction Was continued.

  When the desired particle size is reached, an aqueous solution in which 150 g of sodium chloride is dissolved in 600 ml of ion-exchanged water is added to stop particle growth, and further, the mixture is heated and stirred at a liquid temperature of 98 ° C. as a fusion process, whereby FPIA Fusion between particles was allowed to proceed until the circularity was 0.985 as measured by -2100. Thereafter, the solution was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

(Washing / drying process)
The particles generated in the aggregation / fusion process were solid-liquid separated with a basket type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a wet cake of toner base particles. The wet cake was washed with ion exchange water at 45 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the basket-type centrifuge, and then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). Was dried until the content became 0.5% by mass to prepare colored particles 1. The glass transition point of the colored particles 1 was 22 ° C.

<< Preparation of colored particles 2 >>
In the preparation of the colored particles 1, the second monomer polymerization monomer mass of the resin particles A is 245 g, n-butyl acrylate is 120 g, the third polymerization monomer weight is 423 g of styrene, n-butyl. Colored particles 2 were prepared in the same manner except that the acrylate was changed to 144 g and the methacrylic acid was changed to 33 g, and the agglomeration and fusion steps were carried out so that the circularity was 0.972. The colored glass 2 had a glass transition point of 33 ° C.

<< Preparation of colored particles 3 >>
In the preparation of the colored particles 1, the resin monomer A has a second-stage polymerization monomer weight of 263 g of styrene and n-butyl acrylate of 102 g, a third-stage polymerization monomer weight of styrene 423 g, and n-butyl. Colored particles 3 were prepared in the same manner except that the acrylate was changed to 144 g and the methacrylic acid was changed to 33 g, and the agglomeration and fusion steps were carried out so that the circularity was 0.961. The glass transition point of the colored particles 3 was 40 ° C.

[Production of toner]
《External treatment process》
To 100% by mass of each of the “colored particles 1 to 3” prepared above, fine particle external additives such as hydrophobic silica shown in Table 2 are added in the amounts shown in Table 3, and mixed by a Henschel mixer. Toners 1 to 11 were produced.

[Cyan developer]
Next, a ferrite carrier having a volume average particle diameter of 50 μm coated with a silicone resin was mixed with each of the prepared toners to prepare “Developers 1 to 11” having a toner concentration of 6%.

[Evaluation]
《Image evaluation》
Attach each photoconductor and developer (combined in Table 4) to the image forming unit for black in the digital multifunction machine bizhub C450 remodeled machine (roller charging type, remodeled to paper temperature 110 ° C fixing machine) In a humid (20 ° C, 50% RH) environment, 10,000 copies of original monochrome image data with character images (printing rate 5%) were printed intermittently on A4 fine paper (64 g / m ² ). Image evaluation was performed.

"Evaluation of toner contamination on photoconductor"
The surface of the photoreceptor was visually observed after copying 10,000 sheets, and at the same time, the correlation with the image defect of the output halftone image was evaluated.

Evaluation criteria: A: Little or no toner filming is observed on the surface of the photoreceptor, and no correlated image defects (streaks or speckled image defects) occur (good).

  ○: Toner filming is observed at several places on the surface of the photoreceptor, but no correlated image defects are generated (practicality is possible).

  X: A lot of toner filming was observed on the surface of the photoreceptor, and correlated image defects were also generated (not practical).

"Evaluation of external additive contamination on photoconductor"
The surface of the photoreceptor was visually observed after copying 10,000 sheets, and at the same time, the correlation with the image defect of the output halftone image was evaluated.

Evaluation criteria: A: Little or no adhesion of fine particle external additive was observed on the surface of the photoreceptor, and no correlated image defect (raindrop image defect) occurred (good).

  ○: A slight amount of contamination of the fine particle external additive is observed on the surface of the photoreceptor, but no correlated image defect occurs (practicality is possible).

  X: Adhesion contamination of the fine particle external additive is widely observed on the surface of the photoreceptor, and correlated image defects are also generated (impracticality is impossible).

"Evaluation of charging roller contamination"
A: Little or no contamination such as toner filming is observed on the surface of the charging roller, and no correlated image defects (image defects such as image blur) occur (good).

  ◯: Contamination such as toner filming is observed in several places on the surface of the charging roller, but no correlated image defect occurs (practicality is possible).

  X: Many occurrences of contamination such as toner filming are observed on the surface of the charging roller, and correlated image defects are also generated (not practical).

  From the results of Table 4, combination No. using a photoreceptor containing a charge transport material according to the present invention and a toner containing a fine particle external additive of 1.5% by mass or more and 5.0% or less is used. (Nos. 1-9, 12-16), while any combination obtained a good evaluation result in each evaluation, 10, 11, and 17 show that there is a problem with at least one of the evaluation items.

1 is a schematic cross-sectional view of an image forming apparatus using a contact charging system according to the present invention. 2 is a schematic cross-sectional view of a photosensitive cartridge that is detachable from an image forming apparatus. FIG. It is sectional drawing which showed the structure of the charging roller. 1 is a cross-sectional configuration diagram of a color image forming apparatus using an organic photoreceptor of the present invention.

Explanation of symbols

10Y, 10M, 10C, 10Bk Image forming unit 1Y, 1M, 1C, 1Bk Photoconductor 2Y, 2M, 2C, 2Bk Charging unit 3Y, 3M, 3C, 3Bk Exposure unit 4Y, 4M, 4C, 4Bk Developing unit

Claims (5)

A uniform charge is applied to the organic photoreceptor in the charging process, an electrostatic latent image is formed in the image exposure process, the electrostatic latent image is visualized as a toner image in the development process, and the toner image is transferred to a transfer medium. In the image forming method having a step and a cleaning step of removing residual toner after transfer, the organic photoreceptor has at least a charge generation layer and a charge transport layer, and the charge transport layer comprises the following compounds (1) to (4): ), And the toner used in the development step contains 1.5% by mass or more and 5.0% by mass or less of the fine particle external additive.

The image forming method according to claim 1, wherein the fine particle external additive is inorganic fine particles. 3. The image forming method according to claim 1, wherein the inorganic fine particles contain two or more kinds of inorganic fine particles having different particle diameters. 2. The image forming method according to claim 1, wherein the fine particle external additive contains inorganic fine particles and organic fine particles. Uniform charging is applied using a charging roller in contact with the organic photoreceptor, an electrostatic latent image is formed by the image exposure means, the electrostatic latent image is visualized as a toner image by the developing means, and the toner image is transferred. In an image forming apparatus having a means for transferring to a medium and a cleaning means for removing residual toner after transfer, the organic photoreceptor has at least a charge generation layer and a charge transport layer, and the charge transport layer comprises the following compound (1 An image forming apparatus comprising: at least one of (4) to (4), wherein the toner used in the developing unit contains a fine particle external additive of 1.5% by mass or more and 5.0% by mass or less.

Images