JP6183079B2 - Image forming method - Google Patents

Description

  The present invention relates to an electrophotographic image forming method.

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, by applying a lubricant to a photoconductor, a frictional force between the photoconductor and a cleaning blade, a friction between a toner and a photoconductor. The force has been reduced, thereby preventing the toner from slipping through and achieving good cleaning properties.
As a method for applying the lubricant to the photosensitive member, for example, a device for applying the lubricant to an image forming apparatus and applying the lubricant by the apparatus (see Patent Document 1), or a powder containing a developer containing toner. There is a method of adding a lubricant as an external additive and supplying it to a photoreceptor together with a toner at the time of development (see Patent Document 2). A method of supplying a toner and a toner together with a toner at the time of development has been preferably adopted rather than a method of installing a device for applying a lubricant to a forming device.

On the other hand, from the viewpoint of suppressing the abrasion of the surface of the photoreceptor, a highly durable one having a hardened surface layer as the outermost surface is used. For a photoreceptor having such a hardened surface layer, it is considered preferable to use a fatty acid metal such as zinc stearate having a high lubricating effect as a lubricant.
However, when such a photoconductor is used and a fatty acid metal is used as a lubricant, there is a problem that a lubricant memory may be generated. This occurs because the hardened surface layer of the photoconductor is difficult to be scraped. Specifically, since the supply amount of the lubricant is proportional to the image density of the original, the same original pattern is continuously applied. If a halftone image is output after output, density unevenness (lubricant memory) depending on the original pattern occurs.

Further, conventionally, as a charging device mounted on an electrophotographic image forming apparatus, a device using a corona discharge phenomenon such as a scorotron charger has been widely used. However, a charging device using a corona discharge phenomenon is used. In this case, there is a problem that ozone and nitrogen oxide are generated in the image forming process. On the other hand, when a charging roller type charging device that charges a photoconductor by bringing a conductive charging roller close to or in contact with the photoconductor, the generation of ozone and nitrogen oxides is greatly reduced. In recent years, it has become mainstream because of its high power efficiency.
However, a lubricant memory is more likely to occur in an image forming apparatus that employs such a charging roller type charging device and the photosensitive member on which the cured surface layer is formed. This is considered to be because the lubricant is difficult to remove because it is difficult to remove the photoconductor.

JP 2012-68466 A Japanese Patent Laid-Open No. 2004-233612

  The present invention has been made in view of the above circumstances, and the object thereof is to use a photoreceptor having a cured surface layer in which metal oxide fine particles are contained in a cured resin, and An object of the present invention is to provide an image forming method capable of obtaining excellent cleaning properties for a long period of time and suppressing the generation of lubricant memory even when the photosensitive member is charged by a charging roller.

The image forming method of the present invention comprises a charging step of charging a photoreceptor with a charging roller, an exposure step of forming an electrostatic latent image by exposing the charged photoreceptor, and the electrostatic latent image as an electrostatic image. In an image forming method, comprising: a developing step of developing with a developing toner; a transferring step of transferring a developed toner image onto a transfer material; and a cleaning step of cleaning the photosensitive member with a cleaning blade after transferring the toner image. ,
The photoreceptor has a cured surface layer on an organic photosensitive layer, and the cured surface layer contains metal oxide fine particles in a cured resin obtained by curing a polymerizable compound having at least an acryloyl group or a methacryloyl group. And
The toner for developing an electrostatic charge image used in the development step includes, on the toner base particles, at least a first external additive made of silica (SiO ₂ ) and a second external additive made of a fatty acid metal salt. And a third external additive made of polytetrafluoroethylene.

  In the image forming method of the present invention, it is preferable that the cured surface layer constituting the photoreceptor contains silica fine particles in addition to the metal oxide fine particles.

  In the image forming method of the present invention, it is preferable that the metal oxide fine particles are surface-treated with a surface treatment agent containing a compound having a reactive organic group.

  In the image forming method of the present invention, it is preferable that the cured surface layer constituting the photoreceptor contains a non-reactive charge transport material.

  In the image forming method of the present invention, the non-reactive charge transporting material is preferably represented by the following general formula (1).

[In General Formula (1), R ¹ and R ² each represent a hydrogen atom or a methyl group, and R ³ represents an alkyl group having 1 to 5 carbon atoms. ]

According to the image forming method of the present invention, the first external additive composed of at least silica (SiO ₂ ), the second external additive composed of a fatty acid metal salt, and the polytetrafluoroethylene composed of at least a toner base particle. A photosensitive member having a cured surface layer in which metal oxide fine particles are contained in a cured resin by using an electrostatic charge image developing toner to which an external additive containing 3 external additives is added; Even when the photosensitive member is charged by the charging roller, excellent cleaning properties can be obtained over a long period of time, and generation of lubricant memory can be suppressed.

1 is a cross-sectional view illustrating an example of a configuration of a charging roller type image forming apparatus used in an image forming method of the present invention. FIG. 2 is an explanatory cross-sectional view illustrating an example of a configuration of a charging roller in the image forming apparatus illustrated in FIG. 1.

  Hereinafter, the present invention will be specifically described.

(Image forming method)
The image forming method of the present invention is a general electrophotographic image forming method using a photoconductor having a cured surface layer. The photoconductor in the charging step is charged by a charging roller, and the photoconductor in the cleaning step. Is an image forming method in which the cleaning is performed by a cleaning blade.
Specifically, a charging process for uniformly charging the photoreceptor using a charging roller, an exposure process for forming an electrostatic latent image by exposing the uniformly charged photoreceptor, and this electrostatic latent image. A developing process for developing the image with an electrostatic image developing toner (hereinafter also simply referred to as “toner”), which will be described in detail below, and a toner image obtained by the development is transferred onto a transfer material such as paper. A transfer step, a fixing step of fixing the toner image transferred onto the transfer material onto the transfer material by a contact heating type fixing process, and a cleaning step of cleaning the photosensitive member with a cleaning blade after transferring the toner image. And have.

〔toner〕
The toner used in the image forming method of the present invention includes at least a first external additive composed of silica (SiO ₂ ), a second external additive composed of a fatty acid metal salt, and polytetrafluoro on the toner base particles. A third external additive made of ethylene is added.

By using the toner in which particulate silica (SiO ₂ ), fatty acid metal salt and polytetrafluoroethylene are added to the toner base particles as described above, metal oxide fine particles are contained in the cured resin. Even when a photosensitive member having a cured surface layer is used and the photosensitive member is charged by a charging roller, excellent cleaning properties can be obtained over a long period of time and generation of lubricant memory can be suppressed. it can.
The reason for this is that, since the fatty acid metal salt has a high lubricating effect, excellent cleaning properties can be obtained. Polytetrafluoroethylene has a lower lubricating effect than the fatty acid metal salt, but the polytetrafluoroethylene forms an aggregate with silica (SiO ₂ ), and the aggregate forms the surface of the photoreceptor from the surface of the toner particles. It is presumed that an effect of efficiently moving to the surface can be obtained. The silica (SiO ₂ ) is thought to polish the fatty acid metal salt layer that is inevitably formed on the surface of the photoreceptor by the fatty acid metal salt and causes lubricant memory. As a result, excellent cleaning properties can be obtained over a long period of time, and the occurrence of lubricant memory can be suppressed.

[First external additive]
The number average particle diameter of silica (SiO ₂ ) constituting the first external additive is preferably 10 to 2000 nm, more preferably 30 to 150 nm.
When the number average particle diameter of silica (SiO ₂ ) is 30 nm or more, the adhesion force to the toner particles can be reduced, and the behavior with the toner particles on the photoreceptor is suppressed. It is possible to reliably exhibit the polishing action of the period. By being 150 nm or less, it can be reliably adhered to the surface of the toner particles.

The number average particle diameter of silica (SiO ₂ ) is measured by an image analysis method.
Specifically, a photograph of the toner is taken at a magnification of 30,000 using a scanning electron microscope, the photograph image is captured by a scanner, and the image processing analysis apparatus “LUZEX AP (manufactured by Nireco)” The external additive present on the surface of the toner particles is binarized, the horizontal ferret diameter is calculated for any 100 silica (SiO ₂ ) particles, and the average value is taken as the number average particle diameter.

The addition ratio of silica (SiO ₂ ) is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner base particles.
When the addition ratio of silica (SiO ₂ ) is in the above range, the intended polishing action can be surely exhibited.

[Second external additive]
Examples of the fatty acid metal salt constituting the second external additive include zinc stearate, calcium stearate, aluminum stearate, zinc laurate, and zinc myristate.
These can be used alone or in combination of two or more.

The number average particle diameter of the fatty acid metal salt is preferably 0.5 to 20 μm, more preferably 0.8 to 2 μm.
When the number average particle diameter of the fatty acid metal salt is 0.5 μm or more, the adhesion force to the toner particles can be reduced, and it is suppressed that the fatty acid metal salt behaves together with the toner particles on the photoreceptor. The desired cleaning properties can be obtained with certainty. Moreover, generation | occurrence | production of an image defect can be suppressed reliably because the number average particle diameter of a fatty-acid metal salt is 20 micrometers or less.

  The number average particle diameter of the fatty acid metal salt is the same as the method for measuring the number average particle diameter of the first external additive, except that the horizontal ferret diameter is calculated for 100 fatty acid metal salts. It is obtained.

The addition ratio of the fatty acid metal salt is preferably 0.01 to 0.5 parts by mass, more preferably 0.02 to 0.2 parts by mass with respect to 100 parts by mass of the toner base particles.
When the addition ratio of the fatty acid metal salt is 0.01 parts by mass or more, desired cleaning properties can be obtained with certainty. In addition, since the addition ratio of the second external additive is 0.5 parts by mass or less, it is possible to reliably suppress the toner chargeability from being reduced and to reliably suppress the occurrence of toner scattering and fogging. it can.

[Third external additive]
The polytetrafluoroethylene constituting the third external additive preferably has a number average molecular weight of 500 to 20,000, more preferably 1,000 to 5,000.
By using polytetrafluoroethylene having a number average molecular weight of 500 or more, aggregation with toner base particles in the developing device can be suppressed. Further, by using polytetrafluoroethylene having a number average molecular weight larger than 20,000, sufficient spreadability on the photoreceptor can be obtained, and sufficient cleaning properties can be obtained.

  The number average molecular weight of polytetrafluoroethylene is S.I. This method is obtained in accordance with Wu's method (Polymer Engineering & Science, 1988, Vol. 28, 538, 1989, Vol. 29, 273). This method is a method for calculating the number average molecular weight, weight average molecular weight, and molecular weight distribution from the elastic modulus at the time of melting of the resin, and is particularly useful for measuring the molecular weight of a resin insoluble in a solvent typified by polytetrafluoroethylene. It is. The measuring apparatus uses a viscoelasticity measuring machine “MCR500” manufactured by Anton Paar, and measures dynamic viscoelasticity at 380 ° C. However, a parallel plate is used as a jig for holding the sample, the thickness when the sample is melted is 1.4 to 1.5 mm, and the frequency range is 0.001 to 500 rad / sec. The deformation amount of the sample at the time of melting is selected from a range of 0.8 to 3% on the circumference with respect to the thickness of the sample when the frequency is 1 rad / second or more, and 2 to 2 when the frequency is 1 rad / second or less. Select from a range of 10%. The sampling frequency of the measurement values is 5 points per digit at regular logarithmic intervals. Further, in two consecutive measurements, the measurement is repeated until the average deviation of the storage elastic modulus (G ′ (ω)) at each measurement frequency (ω) is 5% or less. Using the frequency (ω) and storage elastic modulus (G ′ (ω)) obtained by measurement, S.P. The number average molecular weight (Mn) was determined according to the Wu method. However, time t = 1 / ω and G (t) = G ′ (ω).

The number average particle size of the polytetrafluoroethylene is preferably 0.5 to 20 μm, more preferably 0.8 to 2 μm.
When the number average particle diameter of polytetrafluoroethylene is 0.5 μm or more, it is easy to form an aggregate with silica (SiO ₂ ), so that it easily moves to the surface of the photoreceptor. Further, the adhesion force to the toner particles can be reduced, and the behavior with the toner particles on the photoconductor is suppressed, so that the desired cleaning property can be reliably obtained. In addition, when the number average particle diameter of polytetrafluoroethylene is 20 μm or less, formation of aggregates of toner particles on the photoreceptor is suppressed, and black spot-like image defects occur on the obtained image. Can be suppressed.

  The number average particle diameter of the polytetrafluoroethylene is the same as that in the above-described method for measuring the number average particle diameter of the first external additive except that the horizontal ferret diameter is calculated for 100 polytetrafluoroethylenes. Is obtained.

The addition ratio of polytetrafluoroethylene is preferably 0.01 to 1.0 part by mass, and more preferably 0.05 to 0.50 part by mass with respect to 100 parts by mass of the toner base particles.
When the addition ratio of polytetrafluoroethylene is 0.01 parts by mass or more, the polytetrafluoroethylene contained in the toner is easily supplied stably to the surface of the photoreceptor, and sufficient cleaning properties are obtained. . Further, when the addition ratio of polytetrafluoroethylene is 1.0 part by mass or less, sufficient fluidity can be obtained for the toner.

[Other external additives]
The toner according to the present invention includes an external additive other than the first external additive made of silica, the second external additive made of a fatty acid metal salt, and the third external additive made of polytetrafluoroethylene. It may be contained. As other external additives, calcium titanate (CaO ₃ Ti) is preferably used.
When calcium titanate is added as another external additive, the frictional force between the photoreceptor and the cleaning blade can be further reduced. This is presumably because calcium titanate forms an aggregate with the third external additive made of polytetrafluoroethylene, and this aggregate efficiently moves from the surface of the toner particles to the surface of the photoreceptor.
In addition to the above, other external additives may contain those that improve the charging performance and fluidity of the toner. Specifically, inorganic oxide fine particles made of alumina, titanium oxide or the like, composite oxide fine particles, organic fine particles, or the like can be used.

  The amount of the external additive added is the sum of the first external additive, the second external additive, the third external additive, and the other external additives, and is based on 100 parts by mass of the toner base particles. It is preferable that it is 0.1-10.0 mass parts.

  The toner base particles (hereinafter, also referred to as “toner particles”) contain at least a binder resin. If necessary, internal additives such as a colorant, a release agent, and a charge control agent are added. It may be contained.

[Binder resin]
The binder resin constituting the toner particles is not particularly limited, and various known resins can be used. For example, styrene resin, acrylic resin, styrene-acrylic resin, polyester resin, silicone resin, olefin resin Amide resin or epoxy resin.
The binder resin preferably contains a styrene-acrylic resin from the viewpoint of toner particle size, shape controllability and chargeability.

Examples of the polymerizable monomer for obtaining a styrene-acrylic resin include styrene monomers such as styrene, methylstyrene, methoxystyrene, butylstyrene, phenylstyrene, chlorostyrene; methyl (meth) acrylate. , (Meth) acrylate ester monomers such as ethyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl (meth) acrylate; carboxylic acid monomers such as acrylic acid, methacrylic acid and fumaric acid can do.
These can be used alone or in combination of two or more.

The glass transition point (Tg) of the binder resin is preferably 30 to 50 ° C, more preferably 30 to 45 ° C.
When the glass transition point of the binder resin is in the above range, both low-temperature fixability and heat-resistant storage stability can be obtained.

The glass transition point of the binder resin is measured using “Diamond DSC” (manufactured by PerkinElmer).
As a measurement procedure, 3.0 mg of a sample (binder resin) is sealed in an aluminum pan and set in a holder. The reference used an empty aluminum pan. The measurement conditions were a measurement temperature of 0 ° C. 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. Perform analysis based on the data in Heat, draw a baseline extension 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, The intersection point is shown as the glass transition point.

[Colorant]
When the toner particles contain a colorant, generally known dyes and pigments can be used as the colorant.
As a colorant for obtaining a black toner, various known materials such as carbon black such as furnace black and channel black, magnetic materials such as magnetite and ferrite, dyes, and inorganic pigments containing nonmagnetic iron oxide are arbitrarily selected. Can be used.
As the colorant for obtaining a color toner, known ones such as dyes and organic pigments can be arbitrarily used. Specifically, examples of the organic pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 81: 4, 122, 139, 144, 149, 166, 177, 178, 222, 238 269, C.I. I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Blue 15; 3, 60, 76, and the like. Examples of the dye include C.I. I. Solvent Red 1, 49, 52, 58, 68, 11, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 69, 70, 93, 95 and the like.
The colorant for obtaining the toner of each color can be used singly or in combination of two or more for each color.
It is preferable that the content rate of a coloring agent is 1-10 mass parts with respect to 100 mass parts of binder resin, More preferably, it is 2-8 mass parts.

〔Release agent〕
When the toner particles contain a release agent, examples of the release agent include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, paraffin wax, and sazol wax. Long-chain hydrocarbon waxes such as dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, behenate behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehe Esters, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate and other ester waxes, ethylenediamine base Niruamido, an amide-based waxes such as trimellitic acid tristearyl amide.

  The content ratio of the release agent is usually 1 to 30 parts by mass, more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the binder resin. When the content ratio of the release agent is within the above range, sufficient fixing separation property can be obtained.

[Charge control agent]
When the charge control agent is contained in the toner particles, various known compounds can be used as the charge control agent.
The content ratio of the charge control agent is usually 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the binder resin.

[Average particle diameter of toner particles]
The average particle diameter of the toner particles according to the present invention is preferably 3 to 9 μm, and more preferably 3 to 8 μm, for example, in terms of volume-based median diameter. This particle size can be controlled by the concentration of the coagulant used, the amount of organic solvent added, the fusing time, and the composition of the polymer, for example, when the emulsion coagulation method described later is employed.
When the volume-based median diameter is in the above range, the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

The volume-based median diameter of the toner particles is measured and calculated using a measuring device in which “Multisizer 3” (manufactured by Beckman Coulter) is connected to a computer system equipped with data processing software “Software V3.51”. Is.
Specifically, 0.02 g of a sample (toner particles) was added to 20 mL of a surfactant solution (for example, a surfactant obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). Solution) and ultrasonically disperse for 1 minute to prepare a toner particle dispersion. This toner particle dispersion is placed in “ISOTONII” (manufactured by Beckman Coulter) in the sample stand. Pipette into a beaker until the displayed concentration of the measuring device is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measurement apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle size is the volume-based median diameter.

[Average circularity of toner particles]
The toner particles according to the present invention preferably have an average circularity of 0.930 to 1.000, more preferably 0.950 to 0.995, from the viewpoint of improving transfer efficiency.

In the present invention, the average circularity of toner particles is measured using “FPIA-2100” (manufactured by Sysmex).
Specifically, the sample (toner particles) is blended with an aqueous solution containing a surfactant, subjected to ultrasonic dispersion treatment for 1 minute to disperse, and then subjected to measurement conditions HPF by “FPIA-2100” (manufactured by Sysmex). In the (high-magnification imaging) mode, photographing is performed at an appropriate density of 3,000 to 10,000 HPF detections, and the circularity of each toner particle is calculated according to the following formula (T). Calculated by adding the degree and dividing by the total number of toner particles.
Formula (T): Circularity = (perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)

[Toner softening point]
The softening point of the toner is preferably 80 to 120 ° C., more preferably 90 to 110 ° C., from the viewpoint of obtaining low temperature fixability for the toner.

The softening point of the toner is measured by a flow tester shown below.
Specifically, first, in an environment of 20 ° C. and 50% RH, 1.1 g of a sample (toner) was placed in a petri dish and left flat for 12 hours or more, and then a molding machine “SSP-10A” (Shimadzu) Pressed with a force of 3820 kg / cm ² for 30 seconds to produce a cylindrical molded sample having a diameter of 1 cm. Then, the molded sample was subjected to a flow tester “24 ° C. and 50% RH in a flow tester“ CFT-500D "(manufactured by Shimadzu Corporation), with a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds, and a heating rate of 6 ° C./min (1 mm diameter × 1 mm) more, extruded from the time of preheating ends with piston diameter 1 cm, offset method temperature T _offset measured by setting the offset value 5mm at a melt temperature measurement method of temperature ramps is the softening point That.

[Toner Production Method]
The toner according to the present invention includes at least a first external additive made of silica, a second external additive made of a fatty acid metal salt, and a third external additive made of polytetrafluoroethylene. The method for producing the toner particles is not particularly limited, and the kneading and pulverization method, suspension polymerization method, emulsion aggregation method, dissolution suspension method, polyester elongation method, dispersion weight are not particularly limited. Known methods such as legal methods are listed.
Among these, it is preferable to employ an emulsion aggregation method from the viewpoints of particle size uniformity, shape controllability, and ease of forming a core-shell structure, which are advantageous for high image quality and high charge stability.
In the emulsion aggregation method, a dispersion of fine particles of a binder resin (hereinafter also referred to as “resin fine particles”) dispersed by a surfactant or a dispersion stabilizer is used to form a toner particle composition such as fine particles of a colorant as necessary. By mixing with the component dispersion and adding a flocculant to agglomerate until the desired toner particle size is obtained, and thereafter or simultaneously with the agglomeration, the resin fine particles are fused together to control the shape of the toner. A method of forming particles.
Here, the resin fine particles may be composite particles formed of a plurality of layers having two or more layers made of resins having different compositions.
The resin fine particles can be produced, for example, by an emulsion polymerization method, a miniemulsion polymerization method, a phase inversion emulsification method, or the like, or can be produced by combining several production methods. When an internal additive is contained in the resin fine particles, it is preferable to use a miniemulsion polymerization method.
When an internal additive is contained in the toner particles, the resin fine particles may contain an internal additive, or a dispersion of internal additive fine particles consisting of only the internal additive is separately prepared and the internal additive is added. The agent fine particles may be aggregated together when the resin fine particles are aggregated.
Further, when the toner particles are configured to have a core-shell structure, resin fine particles having different compositions may be added at a time difference during aggregation and aggregated.

To the obtained dried toner particles, at least the first external additive powder made of silica, the second external additive powder made of fatty acid metal salt, and the polytetrafluoroethylene first powder. The external additive is added by a dry method of adding and mixing external additives each including the powder of the external additive 3, thereby producing a toner used in the image forming method of the present invention.
As a mixing device for the external additive, various known mixing devices such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer can be used.

(Developer)
The toner according to the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer.
When toner is used as a two-component developer, the mixing amount of the toner with respect to the carrier is preferably 2 to 10% by mass.
A mixing device for mixing the toner and the carrier is not particularly limited, and examples thereof include a Nauter mixer, a W cone, and a V-type mixer.

The carrier preferably has an average particle diameter of 10 to 60 μm in terms of volume-based median diameter.
In the present invention, the volume-based median diameter of the carrier is typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser. It is.

  Further, as the carrier, it is preferable to use a coated carrier in which magnetic particles are used as a core material (core) and the surface thereof is coated with a resin. The resin used for coating the core material is not particularly limited, and various resins can be used. For example, for a toner configured as a positively charged toner, a fluorine-based resin, a fluorine-acrylic acid-based resin is used. Resin, silicone resin, modified silicone resin and the like can be used, and in particular, a condensation type silicone resin is preferably used. For example, for a toner configured as a negatively charged one, styrene-acrylic Resin, mixed resin of styrene-acrylic resin and melamine resin and its cured resin, silicone resin, modified silicone resin, epoxy resin, polyester resin, urethane resin, polyethylene resin, etc. can be used Among them, a mixed resin of styrene-acrylic resin and melamine resin and a cured resin thereof, and It is preferable to use a slip-type silicone resin.

  When the toner according to the present invention is used as a two-component developer, a charge control agent, an adhesion improver, a primer treatment agent, a resistance control agent, etc. are further added to the toner and carrier as necessary. A two-component developer can also be formed.

[Image forming apparatus]
As the image forming apparatus used in the image forming method of the present invention, a charging system having a charging roller system is used. Such a charging roller type image forming apparatus may have a configuration in which the charging roller is provided in contact with the photosensitive member, or may be provided in proximity.
FIG. 1 is an explanatory sectional view showing an example of the configuration of a charging roller type image forming apparatus used in the image forming method of the present invention.
The image forming apparatus includes a drum-shaped photoreceptor 10 that is an electrostatic latent image carrier, a charging roller 11 that applies a uniform potential to the surface of the photoreceptor 10 by corona discharge having the same polarity as the toner, and the like. A charging means including a cleaning roller 15 for cleaning; and an exposure means 12 for forming an electrostatic latent image by performing image exposure on the surface of the uniformly charged photoreceptor 10 by image data using a polygon mirror or the like. A developing means 13 provided with a developing sleeve 13a that is rotated, and the toner held on the developing sleeve 13a is conveyed to the surface of the photoconductor 10 to visualize the electrostatic latent image to form a toner image; Transfer means 14 for transferring the image to the transfer material P as necessary, fixing means 17 for fixing the toner image on the transfer material P, and cleaning blade 18a for removing residual toner on the photoreceptor 10. Those having a cleaning means 18 having.

[Photoreceptor]
The photoreceptor 10 used in the image forming method of the present invention is an organic photoreceptor having a cured surface layer on an organic photosensitive layer.

  The layer structure of the photoreceptor is not particularly limited as long as the organic photosensitive layer and the cured surface layer are laminated in this order on the conductive support. Specifically, the following (1) and (2) The thing which has the following layer structure is mentioned.

(1) Layer structure in which an intermediate layer, a charge generation layer containing a charge generation material as an organic photosensitive layer, a charge transport layer containing a charge transport material, and a cured surface layer are laminated in this order on a conductive support. .
(2) A layer structure in which an intermediate layer, a photosensitive layer containing a charge generation material and a charge transport material as an organic photosensitive layer, and a cured surface layer are laminated in this order on a conductive support.

  In the present invention, the organic photoreceptor means a structure in which at least one of a charge generation function and a charge transport function essential to the configuration of the electrophotographic photoreceptor is exhibited by an organic compound. Includes all known organic photoreceptors such as those having an organic photosensitive layer composed of a generating material or an organic charge transport material, and those having an organic photosensitive layer in which a charge generation function and a charge transport function are composed of a polymer complex Say things.

  Hereinafter, the case where the photoconductor has the layer configuration (1) will be described in detail.

(Cured surface layer)
The cured surface layer in the photoreceptor used in the image forming method of the present invention is a protective layer, and contains metal oxide fine particles in a cured resin obtained by curing a polymerizable compound having at least an acryloyl group or a methacryloyl group. It is supposed to be made.
The metal oxide fine particles contained in the cured surface layer are preferably those that have been surface treated with a surface treating agent containing a compound having a reactive organic group.
The cured surface layer preferably contains silica fine particles, and preferably contains a non-reactive charge transport material. The cured surface layer may contain other components such as an antioxidant and a lubricant as necessary.

  The layer thickness of the cured surface layer is preferably 0.2 to 10 μm, more preferably 0.5 to 5 μm.

(Polymerizable compound)
The cured resin constituting the cured surface layer is obtained by polymerizing and curing a polymerizable compound by irradiation with active rays such as ultraviolet rays and electron beams. As the polymerizable compound, those having two or more polymerizable functional groups are preferably used, and those having one polymerizable functional group can be used in combination. Specifically, examples of the polymerizable compound include styrene monomers, acrylic monomers, methacrylic monomers, vinyl toluene monomers, vinyl acetate monomers, N-vinyl pyrrolidone monomers, and the like.

As the polymerizable compound, an acrylic monomer having two or more acryloyl groups (CH ₂ ═CHCO—) or methacryloyl groups (CH ₂ ═CCH ₃ CO—) can be cured with a small amount of light or in a short time. Or it is especially preferable that they are these oligomers.

  In the present invention, the polymerizable compounds may be used alone or in combination. In addition, these polymerizable compounds may use monomers, but may be used after oligomerization.

  Specific examples of the polymerizable compound are shown below.

However, in the chemical formulas showing the exemplified compounds M1 to M14, R represents an acryloyl group (CH ₂ ═CHCO—), and R ′ represents a methacryloyl group (CH ₂ ═CCH ₃ CO—).

(Metal oxide fine particles)
The cured surface layer contains fine metal oxide particles that have been surface-treated with a surface treatment agent containing a compound having a reactive organic group (hereinafter also referred to as “reactive organic group-containing surface treatment agent”). The metal oxide fine particles are obtained by subjecting metal oxide fine particles (hereinafter also referred to as “untreated metal oxide fine particles”) as a raw material to a surface treatment with a reactive organic group-containing surface treatment agent. A reactive organic group is introduced on the surface of the fine particles.

  Examples of the untreated metal oxide fine particles include silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide), zirconium oxide, tin oxide, titania (titanium oxide), niobium oxide, molybdenum oxide, Vanadium oxide or the like can be used. Among these, it is preferable to use tin oxide from the viewpoints of hardness, conductivity, and light transmittance.

  The number average primary particle size of the metal oxide fine particles is preferably 1 to 300 nm, more preferably 3 to 100 nm, and still more preferably 5 to 40 nm.

  In the present invention, the number average primary particle size of the metal oxide fine particles is a photographic image obtained by taking a magnified photograph of 10,000 times with a scanning electron microscope (manufactured by JEOL Ltd.) and randomly capturing 300 particles with a scanner (aggregation). The number average primary particle size was calculated using an automatic image processing analyzer “LUZEX AP (software version Ver. 1.32)” (manufactured by Nireco Corporation).

The reactive organic group-containing surface treatment agent is preferably one that reacts with a hydroxy group or the like present on the surface of the metal oxide fine particles. Examples of such a reactive organic group-containing surface treatment agent include a silane coupling agent. And titanium coupling agents.
Moreover, as a reactive organic group containing surface treating agent, the surface treating agent which has a radically polymerizable reactive group is preferable. Examples of the radical polymerizable reactive group include a vinyl group, an acryloyl group, and a methacryloyl group. Such a radical polymerizable reactive group can react with the polymerizable compound according to the present invention to form a firm cured surface layer. As the surface treatment agent having a radical polymerizable reactive group, a silane coupling agent having a radical polymerizable reactive group such as a vinyl group, an acryloyl group, or a methacryloyl group is preferable.

  Specific examples of the reactive organic group-containing surface treatment agent include silane coupling agents having an acryloyl group or a methacryloyl group represented by the following exemplary compounds (S-1) to (S-36).

_{S-1: CH 2 = CHSi} (CH 3) (OCH 3) 2
_{S-2: CH 2 = CHSi} (OCH 3) 3
S-3: CH ₂ = CHSiCl _{3
S-4: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
_{S-6: CH 2 = CHCOO} (CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-7: CH 2 = CHCOO} (CH 2) 3 Si (OCH 3) 3
_{S-8: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) Cl 2
_{S-9: CH 2 = CHCOO} (CH 2) 2 SiCl 3
_{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
S-11: CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17: CH 2 = C} (CH 3) COO (CH 2) 2 SiCl 3
_{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19: CH 2 = C} (CH 3) COO (CH 2) 3 SiCl 3
_{S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
_{S-21: CH 2 = C} (CH 3) Si (OCH 3) 3
_{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
_{S-23: CH 2 = CHSi} (OCH 3) 3
_{S-24: CH 2 = C} (CH 3) Si (CH 3) (OCH 3) 2
_{S-25: CH 2 = CHSi} (CH 3) Cl 2
_{S-26: CH 2 = CHCOOSi} (OCH 3) 3
_{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
_{S-28: CH 2 = C} (CH 3) COOSi (OCH 3) 3
_{S-29: CH 2 = C} (CH 3) COOSi (OC 2 H 5) 3
_{S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
_{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
_{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
_{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
_{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
_{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
_{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2

  Moreover, as a reactive organic group containing surface treating agent, you may use the silane compound which has a reactive organic group in which radical polymerization is possible other than what is shown to said S-1 to S-36.

  The reactive organic group-containing surface treatment agent may be used alone or in combination of two or more.

  The treatment amount of the reactive organic group-containing surface treatment agent is preferably 0.1 to 200 parts by mass, more preferably 7 to 70 parts by mass with respect to 100 parts by mass of the untreated metal oxide fine particles.

  Examples of the treatment method for the untreated metal oxide fine particles of the reactive organic group-containing surface treatment agent include, for example, a slurry containing untreated metal oxide fine particles and a reactive organic group-containing surface treatment agent (suspension of solid particles). The method of wet crushing is mentioned. By this method, re-aggregation of the untreated metal oxide fine particles is prevented, and at the same time, the surface treatment of the untreated metal oxide fine particles proceeds. Thereafter, the solvent is removed to form powder.

  Examples of the surface treatment apparatus include a wet media dispersion type apparatus. In this wet media dispersion type device, beads are filled as a medium in a container, and agitation disk mounted perpendicular to the rotation axis is rotated at high speed to crush and pulverize agglomerated particles of untreated metal oxide fine particles. It is an apparatus having a step of dispersing, and the structure thereof is not limited as long as the untreated metal oxide fine particles are sufficiently dispersed and surface treated when performing surface treatment on the untreated metal oxide fine particles. For example, various types such as a vertical type, a horizontal type, a continuous type, and a batch type can be adopted. Specifically, a sand mill, ultra visco mill, pearl mill, glen mill, dyno mill, agitator mill, dynamic mill and the like can be used. These dispersion-type devices are finely pulverized and dispersed by impact crushing, friction, shearing, shear stress, etc., using a grinding medium (media) such as balls and beads.

  As beads used in the wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone, etc. can be used, but those made of zirconia or zircon are particularly preferable. In addition, the size of the beads is preferably about 0.1 to 1.0 mm in the present invention.

  Various materials such as stainless steel, nylon and ceramic can be used for the disk and container inner wall used in the wet media dispersion type apparatus. In the present invention, the disk and container inner wall made of ceramic such as zirconia or silicon carbide are particularly used. Is preferred.

  The content ratio of the metal oxide fine particles in the cured surface layer is preferably 20 to 170 parts by mass, more preferably 25 to 130 parts by mass with respect to 100 parts by mass of the cured resin. The cured resin in the cured surface layer may be considered to be constituted by a curing reaction of all polymerizable compounds contained in the cured surface layer forming coating liquid described later.

(Non-reactive charge transport material)
In the present invention, the non-reactive charge transport material contained in the cured surface layer is a surface treatment of a polymerizable compound or metal oxide fine particles for forming the cured surface layer when the cured surface layer is formed. The thing which does not react with the reactive organic group of the used surface treating agent.
This non-reactive charge transport material has charge transport properties for transporting charge carriers in the cured surface layer, does not substantially exhibit absorption in the ultraviolet region, and has a molecular weight of 450 or less (preferably , 320 or more and 420 or less), and can enter the voids of the cured resin of the cured surface layer. For this reason, it is possible to smoothly inject charge carriers from the charge transport layer without reducing the wear resistance of the cured surface layer, and it is possible to transport charges to the surface of the cured surface layer.

  Examples of the non-reactive charge transport material include compounds represented by the general formula (1).

In general formula (1), R ¹ and R ² each represent a hydrogen atom or a methyl group.

In general formula (1), R < ³ > shows a C1-C5 alkyl group.
Examples of the alkyl group having 1 to 5 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, and n-to. Xyl group, 3-methylpentan-2-yl group, 3-methylpentan-3-yl group, 4-methylpentyl group, 4-methylpentan-2-yl group, 1,3-dimethylbutyl group, 3,3 -A dimethylbutyl group, a 3, 3- dimethylbutan-2-yl group, etc. are mentioned. Of these, from the viewpoint of solubility, a propyl group, an n-butyl group, and an n-pentyl group are preferable.

  Specific examples of the compound represented by the general formula (1) are shown below.

  The compound represented by the general formula (1) can be synthesized by a known synthesis method, for example, a method disclosed in JP-A-2006-143720.

  The content ratio of the non-reactive charge transport material in the cured surface layer is preferably 2 to 60 parts by mass, more preferably 5 to 50 parts by mass, and still more preferably 10 to 100 parts by mass of the cured resin. -35 parts by mass. Further, the content ratio of the non-reactive charge transport material relative to the cured resin may be regarded as the same as the ratio relative to the content ratio of the polymerizable compound in the cured surface layer forming coating liquid described later.

  The cured surface layer according to the present invention may contain other components in addition to the cured resin, the metal oxide fine particles, and the non-reactive charge transport material. For example, various antioxidants can be contained. Various lubricant particles can also be added. For example, fluorine atom-containing resin particles can be added. Examples of the fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluorinated ethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these One or two or more types are preferably selected from the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

  The layer thickness of the cured surface layer is preferably 0.2 to 10 μm, more preferably 0.5 to 6 μm.

  Hereinafter, the structure of the photoreceptor other than the cured surface layer will be described.

[Conductive support]
The conductive support constituting the photosensitive member may have any conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or a sheet, aluminum or copper Metal foils such as those laminated on plastic films, aluminum, indium oxide, tin oxide, etc. deposited on plastic films, metals with conductive layers applied alone or with a binder resin, plastic films and For example, paper.

[Middle layer]
In the photoreceptor, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive support and the organic photosensitive layer. In consideration of various failure prevention, it is preferable to provide an intermediate layer.

  Such an intermediate layer contains, for example, a binder resin (hereinafter also referred to as “binder resin for intermediate layer”) and, if necessary, conductive particles and metal oxide particles.

  Examples of the intermediate layer binder resin include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide resin, polyurethane resin, and gelatin. Among these, alcohol-soluble polyamide resins are preferable.

The intermediate layer can contain various conductive particles and metal oxide particles for the purpose of adjusting the resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide can be used. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used.
The average particle diameter of such metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  These metal oxide particles may be used alone or in combination of two or more. When two or more kinds are mixed, it may take the form of a solid solution or fusion.

  The content ratio of the conductive particles or the metal oxide particles is preferably 20 to 400 parts by mass, more preferably 50 to 350 parts by mass with respect to 100 parts by mass of the binder resin.

  The thickness of the intermediate layer is preferably 0.1 to 15 μm, more preferably 0.3 to 10 μm.

(Charge generation layer)
The charge generation layer in the organic photosensitive layer constituting the photoreceptor contains a charge generation material and a binder resin (hereinafter also referred to as “binder resin for charge generation layer”).

  Examples of charge generation materials include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, pyranthrone and diphthaloylpyrene. Examples thereof include, but are not limited to, ring quinone pigments and phthalocyanine pigments. Among these, polycyclic quinone pigments and titanyl phthalocyanine pigments are preferable. These charge generation materials may be used alone or in combination of two or more.

  As the binder resin for the charge generation layer, known resins can be used. For example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, Polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (eg, vinyl chloride-vinyl acetate copolymer resins, chlorides) Vinyl-vinyl acetate-maleic anhydride copolymer resin), poly-vinylcarbazole resin, and the like, but are not limited thereto. Among these, polyvinyl butyral resin is preferable.

  The content ratio of the charge generation material in the charge generation layer is preferably 1 to 600 parts by mass, more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin for charge generation layer.

  The layer thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin for the charge generation layer, the content ratio, etc., but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm. is there.

(Charge transport layer)
The charge transport layer in the organic photosensitive layer constituting the photoreceptor contains a charge transport material and a binder resin (hereinafter also referred to as “binder resin for charge transport layer”).

  Examples of the charge transport material contained in the charge transport layer include a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, and a butadiene compound as a material that transports charges (holes).

  As the binder resin for the charge transport layer, a known resin can be used. Polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, styrene-methacrylic acid Examples include ester copolymer resins, and polycarbonate resins are preferred.

  The content ratio of the charge transport material in the charge transport layer is preferably 10 to 500 parts by weight, more preferably 20 to 250 parts by weight with respect to 100 parts by weight of the charge transport layer binder resin.

  The layer thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics and the content ratio of the binder resin for the charge transport layer, and is preferably 5 to 40 μm, more preferably 10 to 30 μm.

  In the charge transport layer, an antioxidant, an electronic conductive agent, a stabilizer, silicone oil, or the like may be added. As the antioxidant, those disclosed in JP-A No. 2000-305291 and as the electronic conductive agent are disclosed in JP-A Nos. 50-137543 and 58-76483.

[Method for producing photoreceptor]
The above photoreceptor can be produced, for example, as follows.
Process (1): The process of forming an intermediate | middle layer by apply | coating the coating liquid for intermediate | middle layer formation to the outer peripheral surface of an electroconductive support body, and drying.
Step (2): A step of forming a charge generation layer by applying a coating solution for forming a charge generation layer on the outer peripheral surface of an intermediate layer formed on a conductive support and drying it.
Step (3): A step of forming a charge transport layer by applying a coating liquid for forming a charge transport layer to the outer peripheral surface of the charge generation layer formed on the intermediate layer and drying.
Step (4): A cured surface layer is formed by applying a coating solution for forming a cured surface layer to the outer peripheral surface of the charge transport layer formed on the charge generation layer, drying, and performing a curing treatment by irradiation with active rays or the like. Process.

[Step (1): Formation of intermediate layer]
The intermediate layer is prepared by dissolving an intermediate layer binder resin in a solvent to prepare a coating solution for forming an intermediate layer (hereinafter also referred to as “intermediate layer forming coating solution”). After the metal oxide particles are dispersed, the coating liquid can be formed on the conductive support in a certain film thickness to form a coating film, and the coating film can be dried.
Examples of the coating method for the intermediate layer forming coating solution include known dip coating methods, spray coating methods, spinner coating methods, bead coating methods, blade coating methods, beam coating methods, slide hopper methods, circular slide hopper methods, and the like. A method is mentioned.
The method for drying the coating film can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  The solvent used in the intermediate layer forming step is preferably a solvent in which conductive particles and metal oxide particles are well dispersed and the binder resin for the intermediate layer, particularly the polyamide resin, is dissolved. Specifically, alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol are excellent in solubility and coating performance of polyamide resin. preferable. In addition, examples of co-solvents that can be used in combination with the above-described solvent to improve storage stability and particle dispersibility and obtain a preferable effect include benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The concentration of the binder resin for the intermediate layer in the coating liquid for forming the intermediate layer is appropriately selected according to the thickness of the intermediate layer and the production rate.

  As a means for dispersing the conductive fine particles and metal oxide fine particles, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but is not limited thereto.

[Step (2): Formation of Charge Generation Layer]
The charge generation layer is a coating solution for forming a charge generation layer (hereinafter referred to as “charge generation layer formation coating solution”) by dispersing a charge generation material in a solution in which a binder resin for charge generation layer is dissolved in a solvent. The coating solution is applied on the intermediate layer to a certain film thickness to form a coating film, and the coating film is dried.
As a coating method for the charge generation layer forming coating solution, for example, dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular slide hopper method and the like are known. The method is mentioned.
The method for drying the coating film can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  Examples of the solvent used for forming the charge generation layer include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, t-butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, Examples include, but are not limited to, 4-methoxy-4-methyl-2-pentanone, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

  As a means for dispersing the charge generating substance, for example, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but is not limited thereto.

[Step (3): Formation of Charge Transport Layer]
The charge transport layer is a charge transport layer forming coating solution (hereinafter also referred to as “charge transport layer forming coating solution”) in which a charge transport layer binder resin and a charge transport material are dissolved in a solvent. The coating solution can be formed by coating the charge generation layer with a certain film thickness to form a coating film and drying the coating film.
As a coating method of the coating solution for forming the charge transport layer, for example, dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular slide hopper method and the like are known. The method is mentioned.
The method for drying the coating film can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  Examples of the solvent used for forming the charge transport layer include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, and 1,4. -Dioxane, 1,3-dioxolane, pyridine, diethylamine and the like are exemplified, but not limited thereto.

[Step (4): Formation of cured surface layer]
The cured surface layer is a cured surface layer forming coating solution (hereinafter, referred to as “cured surface layer forming coating solution” in which a polymerizable compound, a non-reactive charge transport material, metal oxide fine particles, and a polymerization initiator are mixed in a solvent. And the coating liquid is applied onto the charge transport layer, a coating film is formed, the coating film is dried, and a curing treatment is performed.

  The cured surface layer as described above is a reaction between reactive organic groups of metal oxide fine particles, a reaction between the reactive organic group and a polymerizable compound, and a reaction between polymerizable compounds in the process of coating, drying and curing. Etc., it is formed as a cross-linked curable resin.

  As the solvent used for forming the cured surface layer, any solvent can be used as long as it can dissolve or disperse the polymerizable compound, the metal oxide fine particles, and the non-reactive charge transport material. For example, methanol, ethanol, n -Propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane , 1,3-dioxolane, pyridine and diethylamine, but are not limited thereto.

  Examples of the application method of the coating solution for forming the hardened surface layer include well-known methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper, and circular slide hopper. The method is mentioned.

  The coating film may be cured without being dried, but it is preferable to perform the curing treatment after natural drying or heat drying.

  Drying conditions can be appropriately selected depending on the type of solvent, film thickness, and the like. The drying temperature is preferably room temperature to 180 ° C, particularly preferably 80 to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

  Examples of the method of reacting the polymerizable compound include a method of reacting by electron beam cleavage and a method of reacting with light and heat by adding a radical polymerization initiator. As the radical polymerization initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used. A photopolymerization initiator and a thermal polymerization initiator can also be used in combination.

Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylazobisvaleronyl), 2,2′-azobis (2-methyl). Azo compounds such as butyronitrile); benzoyl peroxide (BPO), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, etc. And peroxides.
Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (“Irgacure 369” manufactured by BASF Japan Ltd.), 2-hydroxy-2 -Methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) Acetophenone or ketal photoinitiators such as oximes; benzoin, benzoin methyl ether Benzoin ether photopolymerization initiators such as benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether; benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyl Benzophenone photopolymerization initiators such as phenyl ether, acrylated benzophenone, 1,4-benzoylbenzene; 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4- Examples thereof include thioxanthone photopolymerization initiators such as dichlorothioxanthone.
Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, and bis (2,4,6-trimethylbenzoyl). Phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine Compounds, triazine compounds, imidazole compounds and the like. In addition, a photopolymerization accelerator having a photopolymerization promoting effect can be used alone or in combination with the photopolymerization initiator. Examples of the photopolymerization accelerator include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, and 4,4′-dimethylaminobenzophenone. Etc.

  As the radical polymerization initiator, a photopolymerization initiator is preferable, and an alkylphenone compound or a phosphine oxide compound is particularly preferable. In particular, a compound having an α-aminoalkylphenone structure or an acylphosphine oxide structure is preferable.

  The polymerization initiators may be used alone or in combination of two or more.

  It is preferable that the addition ratio of a polymerization initiator is 0.1-20 mass parts with respect to 100 mass parts of polymeric compounds, More preferably, it is 0.5-10 mass parts.

  In this method for producing a photoreceptor, the coating film is irradiated with actinic rays as a curing treatment, radicals are generated and polymerized, and a cross-linking reaction is formed between molecules and within the molecule, and then cured. A cured resin is produced. As the actinic radiation, ultraviolet rays and electron beams are more preferred, and ultraviolet rays are particularly preferred because they are easy to use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, an LED, or the like can be used.
Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² .
The power of the lamp is preferably 0.1 kW to 5 kW, particularly preferably 0.5 kW to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.5 to 10 Mrad.

  The irradiation time for obtaining the necessary amount of active ray irradiation is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of work efficiency.

  In the step of forming the hardened surface layer, drying can be performed before and after irradiating active rays and during irradiation with active rays, and the timing of drying can be appropriately selected by combining these.

  Through the above steps, a photoreceptor having a cured surface layer of a crosslinkable curable resin is obtained.

[Charging roller]
As shown in FIG. 2, the charging roller 11 is laminated on the surface of the core metal 11 a, and an elastic layer 11 b for reducing charging noise and imparting elasticity to obtain uniform adhesion to the photoreceptor 10. On the surface, a charging roller 11 is laminated with a resistance control layer 11c for obtaining a highly uniform electric resistance as a whole as required, and a surface layer 11d is laminated on the resistance control layer 11c. The structure is such that a charging nip portion is formed by being urged in the direction of the photoconductor 10 by a pressing spring 11 e and pressed against the surface of the photoconductor 10 with a predetermined pressing force. It is rotated following the rotation of.

  The cored bar 11a is, for example, plated with a metal such as iron, copper, stainless steel, aluminum and nickel, or the surface of these metals in a range that does not impair the conductivity in order to obtain rust prevention and scratch resistance. The outer diameter is 3 to 20 mm, for example.

  The elastic layer 11b is made of, for example, a material obtained by adding conductive fine particles made of carbon black, carbon graphite, or the like, or conductive salt fine particles made of an alkali metal salt, ammonium salt, or the like to an elastic material such as rubber. Specific examples of the elastic material include natural rubber, ethylene propylene diene methylene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), and butadiene rubber (BR). And synthetic rubbers such as nitrile-butadiene rubber (NBR) and chloroprene rubber (CR), resins such as polyamide resin, polyurethane resin, silicone resin and fluororesin, and foams such as foamed sponge. The magnitude of elasticity can be adjusted by adding process oil, plasticizer and the like to the elastic material.

The elastic layer 11b preferably has a volume resistivity in the range of 1 × 10 ¹ to 1 × 10 ¹⁰ Ω · cm. Moreover, it is preferable that the layer thickness is 500-5000 micrometers, More preferably, it is 500-3000 micrometers.
The volume resistivity of the elastic layer 11b is a value measured according to JIS K 6911.

  The resistance control layer 11c is provided for the purpose of having a uniform electrical resistance for the charging roller 11 as a whole, but may be omitted. The resistance control layer 11c can be provided by coating a material having moderate conductivity or covering a tube having moderate conductivity.

  Specific materials constituting the resistance control layer 11c include basic materials such as resins such as polyamide resin, polyurethane resin, fluororesin, and silicone resin; rubbers such as epichlorohydrin rubber, urethane rubber, chloroprene rubber, and acrylonitrile rubber. Conductive fine particles made of carbon black, carbon graphite, etc .; conductive metal oxide fine particles made of conductive titanium oxide, conductive zinc oxide, conductive tin oxide, etc .; conductive properties made of alkali metal salt, ammonium salt, etc. Examples include those to which a conductive agent such as salt fine particles is added.

The volume resistivity of the resistance control layer 11c is preferably in the range of 1 × 10 ⁻² to 1 × 10 ¹⁴ Ω · cm, more preferably 1 × 10 ¹ to 1 × 10 ¹⁰ Ω · cm. Moreover, it is preferable that the layer thickness is 0.5-100 micrometers, More preferably, it is 1-50 micrometers, More preferably, it is 1-20 micrometers.
The volume resistivity of the resistance control layer 11c is a value measured according to JIS K 6911.

  The surface layer 11d is used for the purpose of preventing bleeding out of the surface of the charging roller where the plasticizer or the like in the elastic layer 11b is obtained, for the purpose of obtaining the slipperiness or smoothness of the surface of the charging roller, or for pinning on the photoreceptor 10. Even if there is a defect such as a hole, it is provided for the purpose of preventing the occurrence of leakage, etc., and it is applied with a material having an appropriate conductivity, or a tube having an appropriate conductivity is coated. Is provided.

  When the surface layer 11d is provided by material coating, specific materials include polyamide resin, polyurethane resin, acrylic resin, fluororesin and silicone resin, epichlorohydrin rubber, urethane rubber, chloroprene rubber and acrylonitrile rubber. Conductive agents such as conductive fine particles made of carbon black, carbon graphite, etc .; conductive metal oxide fine particles made of conductive titanium oxide, conductive zinc oxide, conductive tin oxide, etc. were added to basic materials such as Things. Examples of the coating method include a dip coating method, a roll coating method, and a spray coating method.

  Further, when the surface layer 11d is provided by covering the tube, as a specific tube, nylon 12, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), polyvinylidene fluoride, tetrafluoroethylene-6 Propylene fluorinated copolymer resin (FEP): Polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, polyamide, and other thermoplastic elastomers added with the above conductive agents are molded into tubes The thing which was done is mentioned. This tube may be heat-shrinkable or non-heat-shrinkable.

The surface layer 11d preferably has a volume resistivity in the range of 1 × 10 ¹ to 1 × 10 ⁸ Ω · cm, more preferably 1 × 10 ¹ to 1 × 10 ⁵ Ω · cm. Moreover, it is preferable that the layer thickness is 0.5-100 micrometers, More preferably, it is 1-50 micrometers, More preferably, it is 1-20 micrometers.
The volume resistivity of the surface layer 11d is a value measured according to JIS K 6911.

  The surface layer 11d preferably has a surface roughness Rz of 1 to 30 μm, more preferably 2 to 20 μm, and still more preferably 5 to 10 μm.

In the charging roller 11 as described above, when the charging bias voltage is applied from the power source S1 to the core 11a of the charging roller 11, the surface of the photoconductor 10 is charged to a predetermined potential having a predetermined polarity. Here, the charging bias voltage may be, for example, only a DC voltage, but it is preferably an oscillating voltage in which an AC voltage is superimposed on the DC voltage because of excellent charging uniformity.
The charging bias voltage can be set to, for example, about −2.5 to −1.5 kV.

  An example of the charging conditions by the charging roller shown in FIG. 2 is a sine wave having a DC voltage (Vdc) forming a charging bias voltage of −500 V, an AC voltage (Vac) of 1000 Hz, and a peak-to-peak voltage of 1300 V. By applying this charging bias voltage, the surface of the photoreceptor 10 is uniformly charged to -500V.

  The charging roller 11 has a length based on the length in the longitudinal direction of the photoconductor 10, and the length in the longitudinal direction can be set to 320 mm, for example.

[Cleaning blade]
As the cleaning blade 18a used in the image forming method of the present invention, one made of a rubber material which is an elastic body is preferably used. Examples of rubber materials include urethane rubber, silicon rubber, fluorine rubber, chloropyrene rubber, and butadiene rubber. Among these, urethane rubber is particularly excellent in wear characteristics compared to other rubbers. It is preferable to use urethane rubber.

  The shape and material of the cleaning blade 18a may be appropriately determined according to various conditions such as toner characteristics, photoconductor characteristics, intermediate transfer body, secondary transfer body, contact angle and contact pressure of the cleaning blade 18a. it can.

  The contact pressure of the cleaning blade 18a with the photoconductor 10 is preferably set to about 2.0 to 6.0 gf / mm.

In this image forming apparatus, the photoconductor 10 is rotationally driven, and the surface of the photoconductor 10 is uniformly charged to a predetermined potential by the charging roller 11 in a state where a charging bias voltage is applied from the power source S1.
Next, the uniformly charged photoreceptor 10 is exposed by the exposure unit 12 to form an electrostatic latent image, and the electrostatic latent image is developed by the developing unit 13 to form a toner image. The toner image formed on the photosensitive member 10 is transferred by the transfer unit 14 onto the transfer material P that is transported in time, separated from the photosensitive member 10 by a separation unit (not shown), and then fixed by the fixing unit 17. By fixing, a visible image is formed.
The toner remaining on the photoconductor 10 is removed by the cleaning blade 18a of the cleaning means 18, and the removed toner is stored in the storage unit 18b.

  The image forming apparatus used in the image forming method of the present invention is not limited to the one having the above configuration, and a color image having a configuration in which image forming units related to a plurality of photoconductors are provided along the intermediate transfer body. It may be a forming device.

According to the image forming method as described above, the toner base particles are composed of at least a first external additive composed of silica (SiO ₂ ), a second external additive composed of a fatty acid metal salt, and polytetrafluoroethylene. By using a toner to which an external additive containing a third external additive is added, a photoreceptor having a cured surface layer in which metal oxide fine particles are contained in a cured resin is used, and a charging roller Thus, even when the photosensitive member is charged, excellent cleaning properties can be obtained over a long period of time, and generation of lubricant memory can be suppressed.

  As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

[Toner Preparation Example 1]
(1) Formation of colored particles (toner base particles) (1-1) Production process of resin fine particles [1] for core portion A multilayer structure is obtained through first-stage polymerization, second-stage polymerization and third-stage polymerization shown below. The core resin fine particles [1] were prepared.

(A) First stage polymerization (resin fine particles [A1])
A surfactant solution prepared by dissolving 4 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 3040 parts by mass of ion-exchanged water in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction apparatus. The internal temperature was raised to 80 ° C. while stirring and stirring at a stirring speed of 230 rpm under a nitrogen stream. To this surfactant solution, a polymerization initiator solution in which 10 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 400 parts by mass of ion-exchanged water was added to a temperature of 75 ° C., and then 532 masses of styrene. A monomer mixture consisting of 1 part by weight, 200 parts by weight of n-butyl acrylate, 68 parts by weight of methacrylic acid, and 16.4 parts by weight of n-octyl mercaptan was dropped over 1 hour, and this system was kept at 75 ° C. for 2 hours. Polymerization (first stage polymerization) was carried out by heating and stirring to produce resin fine particles [A1]. The weight average molecular weight (Mw) of the resin fine particles [A1] produced by the first stage polymerization was 16,500.

The weight average molecular weight (Mw) was measured using “HLC-8220” (manufactured by Tosoh Corporation) and the column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation) while maintaining the column temperature at 40 ° C. and tetrahydrofuran as a carrier solvent. (THF) was allowed to flow at a flow rate of 0.2 ml / min, and the measurement sample was dissolved in tetrahydrofuran to a concentration of 1 mg / ml under a dissolution condition in which treatment was performed for 5 minutes using an ultrasonic disperser at room temperature. A sample solution is obtained by treatment with a 2 μm membrane filter, and 10 μl of this sample solution is injected into the apparatus together with the carrier solvent described above, detected using a refractive index detector (RI detector), and the molecular weight of the measurement sample Use a calibration curve whose distribution was measured using monodisperse polystyrene standard particles. And calculate. As a standard polystyrene sample for calibration curve measurement, molecular weights manufactured by Pressure Chemical Co., Ltd. are 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1 .1 × 10 ⁵ , 3.9 × 10 ⁶ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and at least about 10 standard polystyrene samples were measured, and a calibration curve It was created. A refractive index detector was used as the detector.

(B) Second stage polymerization (resin fine particles [A2]: formation of intermediate layer)
In a flask equipped with a stirrer, a monomer mixture comprising 101.1 parts by mass of styrene, 62.2 parts by mass of n-butyl acrylate, 12.3 parts by mass of methacrylic acid, and 1.75 parts by mass of n-octyl mercaptan In addition, 93.8 parts by mass of paraffin wax “HNP-57” (manufactured by Nippon Seiki Co., Ltd.) was added as a release agent, and the mixture was heated to 90 ° C. and dissolved.

  On the other hand, a surfactant solution in which 3 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate was dissolved in 1560 parts by mass of ion-exchanged water was heated to 98 ° C., and the resin fine particles [A1 ] 32.8 parts by mass (in terms of solid content) was added, and the monomer solution containing the paraffin wax was mixed and dispersed for 8 hours using a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. And a dispersion containing emulsified particles having a dispersed particle diameter of 340 nm was prepared. Next, a polymerization initiator solution in which 6 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water was added to this emulsified particle dispersion, and the system was polymerized by heating and stirring at 98 ° C. for 12 hours. (Second-stage polymerization) was performed to produce resin fine particles [A2]. The resin fine particles [A2] prepared by the second stage polymerization had a weight average molecular weight (Mw) of 23,000.

(C) Third-stage polymerization (core resin fine particles [1]: formation of outer layer)
A polymerization initiator solution in which 5.45 parts by mass of potassium persulfate was dissolved in 220 parts by mass of ion-exchanged water was added to the resin fine particles [A2], and 293.8 parts by mass of styrene under a temperature condition of 80 ° C. A monomer mixed solution consisting of 154.1 parts by mass of n-butyl acrylate and 7.08 parts by mass of n-octyl mercaptan was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (third stage polymerization) was performed by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin particles [1] for the core part. The weight average molecular weight (Mw) of the resin fine particles [1] for the core part was 26,800. The volume average particle diameter of the resin fine particles [1] for core portion was 125 nm. Furthermore, the glass transition point (Tg) of the resin fine particles [1] for the core portion was 28.1 ° C.

(1-2) Production process of resin fine particle [1] for shell layer In the first stage polymerization of the resin fine particle [1] for the core part, 548 parts by mass of styrene, 156 parts by mass of 2-ethylhexyl acrylate, methacrylic acid In the same manner except that a monomer mixed solution in which n-octyl mercaptan was changed to 16.5 parts by mass was subjected to a polymerization reaction and post-reaction treatment, and resin particles for shell layer [1] Was made. The glass transition point (Tg) of the resin fine particles for shell layer [1] was 53.0 ° C.

(1-3) Preparation of Colorant Fine Particle Dispersion 90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water, and while stirring this solution, 420 parts by mass of carbon black “Regal 330R” (manufactured by Cabot) Was then gradually added, followed by a dispersion treatment using a stirrer “CLEARMIX” (manufactured by M Technique Co., Ltd.) to prepare a colorant fine particle dispersion [1] in which colorant fine particles were dispersed.
The particle diameter of the colorant fine particles in this colorant fine particle dispersion [1] was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.) and found to be 110 nm.

(1-4) Preparation of toner base particles [1] (a) Formation of core part [1] 420 parts by mass of resin fine particles for core part [1] (solid content conversion), 900 parts by mass of ion-exchanged water, and coloring 100 parts by mass of the agent fine particle dispersion [1] was placed in a reaction vessel equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device and stirred. After adjusting the temperature in the reaction vessel to 30 ° C., 5 mol / liter sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8-11.
Next, an aqueous solution obtained by dissolving 60 parts by mass of magnesium chloride hexahydrate in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the heating was started, and the system was heated to 80 ° C. (core formation temperature) over 80 minutes. In this state, the particle diameter of the particles was measured with “Coulter Multisizer 3” (manufactured by Coulter Inc.), and when the volume-based median diameter (D ₅₀ ) of the particles became 5.8 μm, sodium chloride 40.2 An aqueous solution in which parts by mass are dissolved in 1000 parts by mass of ion-exchanged water is added to stop the growth of the particle size, and further, as an aging treatment, the mixture is heated and stirred at a liquid temperature of 80 ° C. (core part aging temperature) for 1 hour. Wearing was continued to form the core [1]. The circularity of the core [1] was 0.930 as measured by “FPIA2100” (manufactured by Sysmex Corporation). In addition, using a field emission scanning electron microscope JSM-7401F (manufactured by JEOL Ltd.), the core part [1] was observed at a magnification of 10,000 by scanning transmission electron microscopy, and the colorant was dissolved in the binder resin. It was confirmed that no colorant-dispersed fine particles remained.

(B) Formation of Shell Layer Next, 46.8 parts by mass of resin fine particles for shell layer [1] (in terms of solid content) are added at 65 ° C., and further 2 parts by mass of magnesium chloride hexahydrate is added to ion-exchanged water 60 An aqueous solution dissolved in parts by mass was added over 10 minutes, and then the temperature was raised to 80 ° C. (shell formation temperature), and stirring was continued for 1 hour. Resin fine particles for the shell layer were formed on the surface of the core part [1]. After fusing the particles of [1], aging treatment was performed at 80 ° C. (shell aging temperature) to a predetermined circularity to form a shell layer. Here, an aqueous solution in which 40.2 parts by mass of sodium chloride was dissolved in 1000 parts by mass of ion-exchanged water was added, and the mixture was cooled to 30 ° C. at 8 ° C./min. By repeatedly washing with exchanged water and then drying with hot air of 40 ° C., the volume-based median diameter (D ₅₀ ) having a shell layer on the surface of the core part is 5.9 μm, and the glass transition point (Tg) is Toner base particles [1] at 31 ° C. were obtained.

(2) Addition of external additive To 100 parts by mass of the dried toner base particles [1], 0.15 part by mass of polytetrafluoroethylene (average molecular weight 1,000, particle size 1 μm), zinc stearate (particle size 15 μm) ) 0.07 parts by mass, 1 part by mass of negatively chargeable silica “RX-200 (manufactured by Nippon Aerosil Co., Ltd.)” and 1 part by mass of negatively chargeable silica “NX90 (manufactured by Nippon Aerosil Co., Ltd.)” were added. (Nippon Coke Co., Ltd.) using a rotating blade peripheral speed of 35 m / sec and a processing temperature of 32 ° C. for 20 minutes, and then removing coarse particles using a sieve having an opening of 45 μm. 1] was produced.

[Toner Preparation Examples 2 to 9]
Toners [2] to [9] were prepared in the same manner as in (2) External additive addition step in Toner Preparation Example 1 except that external additives were used according to the formulation shown in Table 1 below. .

[Manufacture of developer]
For each of the toners [1] to [9], a developer carrier [1] to [9] is mixed by mixing a ferrite carrier having a volume average particle diameter of 35 μm coated with a silicone resin so that the toner concentration becomes 7.5% by mass. [9] was prepared.

[Photosensitive body preparation example 1]
As shown below, an intermediate layer and an organic photosensitive layer composed of a charge generation layer and a charge transport layer are laminated in this order on a conductive support, and a cured surface layer is formed as a surface layer on the organic photosensitive layer. An organophotoreceptor [1] having a layered structure was prepared.
(1) Production of conductive support A conductive support [1] was prepared by cutting the surface of a cylindrical aluminum support having a diameter of 30 mm to make the surface fine and rough.

(2) Formation of intermediate layer A dispersion having the following composition was diluted twice with the same mixed solvent, allowed to stand overnight and then filtered (filter; using a lymesh 5 μm filter manufactured by Nihon Pall Co., Ltd.). 1] was prepared.
-Binder resin: Polyamide resin "CM8000" (manufactured by Toray Industries, Inc.) 1 part by mass-Metal oxide particles: Titanium oxide "SMT500SAS" (manufactured by Teika) 3 parts by mass-Solvent: Methanol 10 parts by mass Using a sand mill as a disperser The dispersion was carried out for 10 hours in a batch mode.
This intermediate layer forming coating solution [1] was applied on the conductive support [1] by a dip coating method to form an intermediate layer [1] having a dry film thickness of 2 μm.

(3) Formation of charge generation layer Charge generation material: 20 parts by mass of the following pigment (CG-1) Binder resin: Polyvinyl butyral resin “# 6000-C” (manufactured by Denki Kagaku Kogyo)
10 parts by mass Solvent: 700 parts by mass of t-butyl acetate Solvent: 4-Methoxy-4-methyl-2-pentanone 300 parts by mass are mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. did. This charge generation layer coating solution was applied onto the intermediate layer [1] by a dip coating method and dried to form a charge generation layer [1] having a dry film thickness of 0.3 μm.

<Synthesis of Pigment (CG-1)>
(1) Synthesis of amorphous titanyl phthalocyanine 1,3-diiminoisoindoline; 29.2 parts by mass are dispersed in 200 parts by mass of o-dichlorobenzene, and titanium tetra-n-butoxide; 20.4 parts by mass are added. It heated at 150-160 degreeC for 5 hours under nitrogen atmosphere. After allowing to cool, the precipitated crystals were filtered, washed with chloroform, washed with 2% aqueous hydrochloric acid, washed with water, washed with methanol, and dried to obtain 26.2 parts by mass (yield 91%) of crude titanyl phthalocyanine.
Next, the crude titanyl phthalocyanine was dissolved by stirring for 1 hour in 250 parts by mass of concentrated sulfuric acid at 5 ° C. or less, and this was poured into 5000 parts by mass of water at 20 ° C. The precipitated crystals were filtered and sufficiently washed with water to obtain 225 parts by mass of a wet paste product.
This wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain 24.8 parts by mass of amorphous titanyl phthalocyanine (yield 86%).

(2) Synthesis of (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine (CG-1) 10.0 parts by mass of the above amorphous titanyl phthalocyanine and (2R, 3R) -2,3-butanediol 0 .94 parts by mass (0.6 equivalent ratio) (equivalent ratio is equivalent to titanyl phthalocyanine, hereinafter the same) was mixed in 200 parts by mass of orthochlorobenzene (ODB), and heated and stirred at 60 to 70 ° C. for 6.0 hours. After standing overnight, methanol was added to the reaction solution, and the resulting crystals were filtered. The crystals after filtration were washed with methanol (a pigment containing (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine). CG-1: 10.3 mass parts was obtained. In the X-ray diffraction spectrum of the pigment (CG-1), there are clear peaks at 8.3 °, 24.7 °, 25.1 °, and 26.5 °. There is a peak in the 576 and 648 in the mass spectra, O-Ti-O both absorption appears Ti = O near 970 cm ^-1, around 630 cm ^-1 in the IR spectrum. In addition, since thermal analysis (TG) has a mass loss of about 7% at 390 to 410 ° C., a 1: 1 adduct and a non-adduct (addition) of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol (Not) presumed to be a mixture of titanyl phthalocyanine.
It was 31.2 m < ² > / g when the BET specific surface area of the obtained pigment (CG-1) was measured with the flow type specific surface area automatic measuring apparatus (Micrometrics flow soap type: Shimadzu Corporation).

(4) Formation of charge transport layer 225 parts by mass of charge transport material (compound A below) Binder: 300 parts by mass of polycarbonate resin “Z300” (Mitsubishi Gas Chemical) • Antioxidant “Irganox 1010” (manufactured by Ciba Geigy Japan) ) 6 parts by mass-Solvent: THF (tetrahydrofuran) 1600 parts by mass-Solvent: 400 parts by mass of toluene-Silicone oil "KF-50" (manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass dissolved to form a coating solution for forming a charge transport layer [1 Was prepared.
The charge transport layer forming coating solution [1] was applied onto the charge generation layer [1] using a circular slide hopper coating apparatus to form a charge transport layer [1] having a dry film thickness of 20 μm.

(5) Formation of cured surface layer First, the surface treatment of metal oxide fine particles was performed with a surface treatment agent having a reactive organic group as follows.
Metal oxide fine particles: Tin oxide (manufactured by CIK Nanotech Co., Ltd., number average primary particle diameter 20 nm, volume resistivity: 1.05 × 10 ⁵ (Ω · cm)) 100 parts by mass, surface treatment agent: above-mentioned exemplified compound (S _{-15: CH 2 = C (CH} 3) COO (CH 2) 3 Si (OCH 3) 3) 30 parts by mass, solvent: a mixed solvent mixture 300 parts by weight of toluene / isopropyl alcohol = 1/1 (weight ratio) The liquid is put into a sand mill together with zirconia beads, stirred at a rotational speed of 1500 rpm at about 40 ° C., and the treated mixture is taken out, put into a Henschel mixer and stirred at a rotational speed of 1500 rpm for 15 minutes, and then at 120 ° C. for 3 hours. By drying, surface treatment with a compound having a reactive organic group for tin oxide was performed to obtain surface-treated tin oxide.
By this surface treatment, the particle surface of tin oxide was coated with the exemplary compound (S-15).

-Surface-treated tin oxide 80 parts by mass-Polymerizable compound (Exemplified Compound M1) 100 parts by mass-Non-reactive charge transport material (Exemplified Compound CTM-8) 20 parts by mass-Polymerization initiator "Irgacure 819" ( BASF Japan Ltd.) 10 parts by mass-Silica fine particles "RX-50" (Nippon Aerosil Co., Ltd.) 25 parts by mass-2-butanol 320 parts by mass-Tetrahydrofuran 80 parts by mass The composition of the coating solution is sufficiently mixed and stirred. Then, a coating solution for forming a cured surface layer was prepared. The coating solution for forming the cured surface layer is applied onto the charge transport layer [1] using a circular slide hopper applicator, and after application, the coating is irradiated with ultraviolet rays for 1 minute using a metal halide lamp, resulting in a dry film thickness of 3 A cured surface layer having a thickness of 0.0 μm was formed, whereby a photoreceptor [1] was produced.

[Photoconductor Preparation Examples 2 to 4]
In the formation process of the (5) cured surface layer in the photoreceptor production example 1, the addition amount of the silica fine particles was changed to 5 parts by mass, 50 parts by mass, and 0 parts by mass (not added), respectively. Photoconductors [2] to [4] were prepared.

[Photoconductor Preparation Example 5]
In the same manner as in Preparation Example 1 of the photoreceptor, an intermediate layer, a charge generation layer, and a charge transport layer were formed on the conductive support. Then
-Charge transport material (compound A) 75 parts by mass-Binder: Polycarbonate resin "Z300" (Mitsubishi Gas Chemical Co., Ltd.) 100 parts by mass-Antioxidant "Irganox 1010" (Nippon Ciba Geigy) 2 parts by mass-Silica fine particles " RX-50 "(manufactured by Nippon Aerosil Co., Ltd.) 25 parts by mass-Solvent: THF (tetrahydrofuran) 533 parts by mass-Solvent: Toluene 133 parts by mass-Silicone oil" KF-50 "(manufactured by Shin-Etsu Chemical Co., Ltd.) From 0.33 parts by mass The composition of the resulting coating solution was mixed and stirred to sufficiently dissolve or disperse to prepare a surface layer forming coating solution [5].
This surface layer forming coating solution [5] is applied onto the charge generation layer using a circular slide hopper coating apparatus, and dried at 120 ° C. for 70 minutes to form a surface layer having a dry film thickness of 3.0 μm, Thus, a photoreceptor [5] was produced.

<Examples 1-10, Comparative Examples 1-3>
The charging means of the digital color multifunction peripheral “bizhub C360” (manufactured by Konica Minolta Co., Ltd.) is remodeled into a charging roller type as shown in FIG. 1, and the above photoreceptors [1] to [5] are used as the photoreceptors according to Table 3. In accordance with Table 3, developers [1] to [9] were loaded and used to form images, and the lubricant memory and cleaning properties were evaluated.
As the charging roller, a nylon resin having a diameter of 1.0 cmφ was used.
The cleaning blade was installed so that the angle formed with the photoconductor was 7.5 ° and the contact pressure was 7.0 gf / mm ² .

(1) Lubricant memory In a high-temperature and high-humidity environment (temperature 30 ° C., humidity 85% RH), after 100 pattern images having an image portion A and a non-image portion B are output in succession, the entire halftone image is 1 Output. For this halftone image, “Macbeth RD920” (manufactured by Macbeth) was used to measure the reflection density (D1) of the portion corresponding to the image portion A and the reflection density (D0) of the portion corresponding to the non-image portion B. Then, the density difference ΔD (D1−D0) was calculated, thereby evaluating the degree of occurrence of image density unevenness. The results are shown in Table 1.
In the present invention, if ΔD is less than 0.3, it is judged that there is no practical problem, and if it is less than 0.1, it is evaluated as excellent.

(2) Cleaning property In a low-temperature and low-humidity environment (temperature: 10 ° C., humidity: 10% RH), the surface of the photoconductor after 2,000 test images having a pixel rate of 5% were output continuously was visually observed. Evaluation was performed according to the following evaluation criteria. The results are shown in Table 1.
In the present invention, it is judged that there is no practical problem if it is “◯” or “Δ”.
-Evaluation criteria-
○: No deposits are observed on the surface of the photoreceptor.
X: One or more deposits are observed on the surface of the photoreceptor.

DESCRIPTION OF SYMBOLS 10 Photoconductor 11 Charging roller 11a Metal core 11b Elastic layer 11c Resistance control layer 11d Surface layer 11e Pressure spring 12 Exposure means 13 Development means 13a Development sleeve 14 Transfer means 15 Cleaning roller 17 Fixing means 18 Cleaning means 18a Cleaning blade 18b Storage part P Transfer material

Claims (5)

A charging step for charging the photosensitive member with a charging roller, an exposure step for forming an electrostatic latent image by exposing the charged photosensitive member, and a developing step for developing the electrostatic latent image with toner for developing an electrostatic image. And an image forming method comprising: a transfer step of transferring the developed toner image to a transfer material; and a cleaning step of cleaning the photosensitive member with a cleaning blade after transferring the toner image.
The photoreceptor has a cured surface layer on an organic photosensitive layer, and the cured surface layer contains metal oxide fine particles in a cured resin obtained by curing a polymerizable compound having at least an acryloyl group or a methacryloyl group. And
The toner for developing an electrostatic charge image used in the development step includes, on the toner base particles, at least a first external additive made of silica (SiO ₂ ) and a second external additive made of a fatty acid metal salt. And an image forming method comprising: adding a third external additive made of polytetrafluoroethylene.   2. The image forming method according to claim 1, wherein the cured surface layer constituting the photoconductor contains silica fine particles in addition to the metal oxide fine particles.   The image forming method according to claim 1, wherein the metal oxide fine particles are surface-treated with a surface treatment agent containing a compound having a reactive organic group.   The image forming method according to any one of claims 1 to 3, wherein the cured surface layer constituting the photoconductor contains a non-reactive charge transport material. The image forming method according to claim 4, wherein the non-reactive charge transport material is represented by the following general formula (1).

[In General Formula (1), R ¹ and R ² each represent a hydrogen atom or a methyl group, and R ³ represents an alkyl group having 1 to 5 carbon atoms. ]

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