JP2008070718A - Image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and a process cartridge that can achieve both of favorable removal of a discharge product and favorable toner cleaning property. <P>SOLUTION: The image forming apparatus includes at least an image holding body, an electrostatic latent image forming means that forms a latent image on the image holding body, a developing means that develops the latent image with toner to form a visible image, a transferring means that transfers the visible image to a recording medium and a cleaning means that removes the toner remaining on the image holding body after transfer by using a cleaning blade, and characterized in that: the toner comprises first inorganic particles having a number average particle diameter of 30 nm or less and containing a free surface treating agent by 2 to 50 mass%, and second inorganic particles having a number average particle diameter of 80 to 200 nm; and the pushing pressure of the cleaning blade to the image holding body is 1.0×10<SP>-2</SP>to 3.5×10<SP>-2</SP>mN/cm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that performs image formation by electrophotography and electrostatic recording, and a process cartridge used in the image forming apparatus.

  As a charging device for charging the image holding member by uniformly applying a charge to the surface of the image holding member holding the toner image, a non-contact charging method such as a scorotron or corotron using corona discharge, There are known two types of charging systems such as a contact charging system using a charging roller using discharge in a gap.

  In a charging device using corona discharge, a corona discharge is generated between the image carrier and the wire by applying a high voltage to the wire stretched opposite the surface of the image carrier to which charge is to be applied. Then, a predetermined charge is applied to the image carrier. This type of charger has the advantages of excellent charging uniformity and high-speed suitability, and lower torque of the pressing part of the blade and the image carrier than the contact charging method. There is a drawback in that image flow is caused by discharge products such as nitrogen oxides.

  When the discharge product adheres, the resistance of the surface of the image carrier is lowered, or the electrostatic characteristics thereof are deteriorated, for example, whitening of the image (image flow) occurs. The white spots in the image due to the adhesion of the discharge products tend to be prominent particularly under high temperature and high humidity.

  For example, as an image forming apparatus using a toner to which an external additive is added, a monodispersed large-diameter silica is used to improve the fluidity, chargeability, developability, transferability, and fixability of the toner (for example, Patent Document 1). And a method of using monodispersed large-diameter silica to suppress blade damage and obtain stable cleaning properties (see, for example, Patent Document 2), and the like, and can be expected to suppress toner slipping (cleaning failure). However, even when a low-abrasion type image carrier or a wear-type photosensitive member is used for low wear, the discharge product removal effect is still insufficient and there is room for improvement.

  Further, as a method using specific external additives having different particle diameters, a method for suppressing a decrease in toner cleaning properties and a photoreceptor damage (for example, see Patent Document 3) has been proposed. However, although an improvement effect is expected for a kneaded and pulverized toner having a large particle size, the effect on a substantially spherical toner prepared by a polymerization method is insufficient, and further, the toner base particles are not improved by a small-diameter external additive. Since the fluidity is improved, when used for a small-diameter substantially spherical toner, there is a disadvantage that the penetration property to the pressing portion between the blade and the image carrier is increased and the toner cleaning property is insufficiently improved.

  Further, there has been proposed a method (see, for example, Patent Document 4) that uses a high hardness blade to increase the pressing pressure against the image carrier to achieve both cleaning properties and removal of discharge products. However, damage and wear may occur depending on the image carrier used.

  Further, a method of using two blades and using a cleaning brush in combination (for example, see Patent Documents 5 and 6) has been proposed, but there are problems in terms of applicability to a small apparatus and cleaning of the cleaning brush. there were.

That is, a method for achieving a high level of toner cleaning properties and discharge product removal properties has not yet existed, and further improvements have been desired.
JP 2001-0666820 A Japanese Patent Laid-Open No. 2005-4051 JP 2002-268271 A JP 2005-164619 A JP-A-7-181852 JP 2004-170440 A

An object of the present invention is to solve the above-described problems in the prior art.
That is, an object of the present invention is to provide an image forming apparatus and a process cartridge that can achieve good removal of discharge products and good toner cleaning properties.

The object of the present invention is achieved by the following present invention.
That is, the image forming apparatus of the present invention is
<1> An image holding member, an electrostatic latent image forming unit that forms a latent image on the image holding member, a developing unit that develops the latent image with toner to form a visible image, and the visible image At least a transfer unit that transfers to a recording medium and a cleaning unit that removes toner remaining on the image carrier after transfer using a cleaning blade. The toner is free with a number average particle size of 30 nm or less. A first inorganic particle having a surface treatment agent amount of 2 to 50% by mass and a second inorganic particle having a number average particle diameter of 80 to 200 nm, and pressing the cleaning blade against the image carrier The image forming apparatus is characterized in that the pressure is 1.0 × 10 ^{−2 to} 3.5 × 10 ⁻² mN / cm.
<2> The image forming apparatus according to <1>, wherein the powder fluidity is 5 to 30%.

The process cartridge of the present invention is
<3> An image holding member that is detachable from a loading portion of the image forming apparatus, a developing device that forms a visible image by developing a latent image formed on the image holding member with toner, and an image holding A cleaning device that removes toner remaining on the body using a cleaning blade, wherein the toner has a number average particle size of 30 nm or less and a free surface treatment amount of 2 to 50% by mass. Inorganic particles and second inorganic particles having a number average particle diameter of 80 to 200 nm, and the pressing pressure of the cleaning blade against the image carrier is 1.0 × 10 ^{−2 to} 3.5 ×. It is a process cartridge characterized by being 10 ⁻² mN / cm.

  According to the present invention, it is possible to provide an image forming apparatus and a process cartridge capable of achieving good removal of discharge products and good toner cleaning properties.

The image forming apparatus of the present invention includes an image carrier, an electrostatic latent image forming unit that forms a latent image on the image carrier, a developing unit that develops the latent image with toner to form a visible image, The image forming apparatus includes at least a transfer unit that transfers the visible image to a recording medium, and a cleaning unit that removes toner remaining on the image holding member after transfer using a cleaning blade. The toner includes first inorganic particles having a number average particle diameter of 30 nm or less and a free surface treating agent amount of 2 to 50% by mass, and second inorganic particles having a number average particle diameter of 80 to 200 nm. The pressure of pressing the cleaning blade against the image carrier is 1.0 × 10 ^{−2 to} 3.5 × 10 ⁻² mN / cm.

  Under compaction in the vicinity of the pressing portion (nip) between the image carrier and the cleaning blade, the second inorganic particles (large-diameter external additive) and the first inorganic particles containing the free surface treatment agent (small-diameter external additive) Rolling contact of the large-diameter external additive increases. For this reason, the entry of the large-diameter external additive into the pressing portion is reduced, and the external additive mainly composed of the large-diameter external additive (slow agglomerate) is located near the pressing portion (nip) between the image carrier and the cleaning blade. Then, the toner is formed and accumulated by being damped by a dam of external additives (slow agglomerates). Since the accumulated material serves as a dam for clogging the discharge product, the discharge product can be removed well. Further, the accumulation of loose agglomerates can more effectively suppress slipping of toner and the like, and good toner cleaning properties can be obtained.

  In the case of an image forming apparatus using a non-contact type charging device, the effect can be exhibited more significantly by applying the image forming apparatus of the present invention. Although the detailed reason is unknown, it is assumed that the non-contact charging method generates a larger amount of discharge products than the contact charging method.

In the following, toner used in the image forming apparatus of the present invention will be described first.
[Electrostatic latent image developing toner]
The toner according to the present invention includes a first inorganic particle having a number average particle diameter of 30 nm or less and a free surface treating agent amount of 2 to 50% by mass, and a second inorganic particle having a number average particle diameter of 80 to 200 nm. And containing.

(External additive)
In the toner of the present invention, as the external additive, first inorganic particles (small external additive) having at least a number average particle size of 30 nm or less and a free surface treating agent amount of 2 to 50% by mass, and a number average particle are used. 2nd inorganic particle (large-diameter external additive) whose diameter is 80-200 nm is contained.

-Second inorganic particles (external additive for large diameter)-
The large-diameter external additive used in the present invention has a number average particle diameter of 80 to 200 nm. When the number average particle diameter is larger than 200 nm, the contact area with the small-diameter external additive is reduced, so that it is difficult to form slow aggregation. On the other hand, if the thickness is less than 80 nm, the adhesion to the toner surface increases, so the chance of contact with the small-diameter external additive decreases, and it is difficult to form loose aggregation.
The number average particle diameter of the large-diameter external additive is more preferably 100 to 150 nm, and particularly preferably 110 to 130 nm.

  A method for measuring the number average particle diameter of the external additives (the large-diameter external additive and the small-diameter external additive described later) will be described later.

As the large-diameter external additive, monodispersed spherical silica is preferably used particularly from the viewpoint of improving toner cleaning properties, improving transfer properties, and reducing torque. Since monodispersed spherical silica is monodispersed and spherical, it can be uniformly dispersed on the surface of the toner base particles, and a stable spacer effect can be obtained.
The definition of the monodispersion can be discussed in terms of the standard deviation with respect to the average particle diameter including aggregates, and the standard deviation is preferably number average particle diameter × 0.22 or less. In addition, the definition of the sphere in the present invention can be discussed in terms of Wadell's sphericity, and the sphericity is preferably 0.6 or more, and more preferably 0.8 or more.
The reason why silica is particularly preferable is that the refractive index is around 1.5, and even if the particle size is increased, the transparency is lowered due to light scattering, and particularly the haze value at the time of taking an image on OHP is affected. Not to mention.

  General fumed silica has a true specific gravity of 2.2, and the maximum particle size of 50 nm is a limit from the viewpoint of production. Moreover, although the particle size can be increased as an aggregate, uniform dispersion and a stable spacer effect cannot be obtained. On the other hand, other typical inorganic particles used as external additives include titanium oxide (true specific gravity 4.2, refractive index 2.6), alumina (true specific gravity 4.0, refractive index 1.8), oxidation Zinc (true specific gravity of 5.6, refractive index of 2.0) can be mentioned, but all of them have high true specific gravity, and when the particle size is 80 nm or more that effectively expresses the spacer effect, peeling from the toner base particles is likely to occur. The peeled particles are easily transferred to a charge imparting member, an image carrier, or the like, which causes charge reduction or image quality defects. Also, since the refractive index is high, it is not suitable for producing color images to use inorganic particles having a large particle size.

  The monodispersed spherical silica having a number average particle size of 80 to 200 nm in the present invention can be obtained by a sol-gel method which is a wet method. The particle size can be freely controlled by the hydrolysis of the sol-gel method, the weight ratio of alkoxysilane, ammonia, alcohol, water in the condensation polymerization step, the reaction temperature, the stirring rate, and the supply rate. Monodisperse and spherical shapes can also be achieved by making this technique.

  Specifically, tetramethoxysilane is dropped and stirred while applying temperature using ammonia water as a catalyst in the presence of water and alcohol. Next, the silica sol suspension obtained by the reaction is centrifuged to separate into wet silica gel, alcohol and aqueous ammonia. A solvent is added to wet silica gel to form a silica sol again, and a hydrophobizing agent is added to hydrophobize the silica surface. Next, the target monodispersed spherical silica can be obtained by removing the solvent from the hydrophobized silica sol, drying, and sieving. Further, the silica thus obtained may be treated again. Next, the silica external additive of the present invention can be obtained by removing the solvent from the hydrophobized silica sol and drying it.

Furthermore, a dry method such as a spray drying method in which a treatment agent or a solution containing a treatment agent is sprayed on particles suspended in a gas phase, or a wet method in which particles are immersed in a solution containing a treatment agent and dried. It can be processed by a method, a mixing method in which a processing agent and particles are mixed by a mixer. Further, after the surface treatment, a step of washing with a solvent and removing a residual treatment agent or a low-boiling residue may be added.
In addition, the manufacturing method of the monodispersed spherical silica in this invention is not limited to the said manufacturing method.

  As the hydrophobizing agent, a general coupling agent, silicone oil, fatty acid, fatty acid metal salt, or the like can be used, but it is preferable to perform surface treatment including a silane coupling agent from the viewpoint of production stability. .

The said silane compound can use a water-soluble thing.
As such a silane compound, chemical structural formula R _a SiX _4-a (wherein, a is an integer of 0 to 3, R represents an organic group such as a hydrogen atom, an alkyl group, and an alkenyl group; Represents a hydrolyzable group such as a chlorine atom, a methoxy group, and an ethoxy group.), And any type of chlorosilane, alkoxysilane, silazane, and a special silylating agent is used. It is also possible.
Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (Trimethylsilyl) urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxy Silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercapto Representative examples include propyltrimethoxysilane and γ-chloropropyltrimethoxysilane.
Particularly preferably, the hydrophobizing agent in the present invention includes dimethyldimethoxysilane, hexamethyldisilazane, methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane and the like.

  Specific examples of silicone oils include, for example, organosiloxane oligomers; cyclic compounds such as octamethylcyclotetrasiloxane or decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, tetravinyltetramethylcyclotetrasiloxane, linear or branched Can be mentioned. Alternatively, a highly reactive silicone oil in which a modifying group is introduced at a side chain, one end, both ends, side chain one end, side chain both ends, or the like may be used. Examples of the modifying group include alkoxy, carboxyl, carbinol, higher fatty acid modification, phenol, epoxy, methacryl, amino and the like, but are not particularly limited. Further, it may be a silicone oil having several kinds of modifying groups such as amino / alkoxy modification.

  Further, dimethyl silicone oil, these modified silicone oils, and other surface treatment agents may be mixed or used in combination (such as silane coupling agents (including HMDS), etc.). ). Examples of the treating agent used in combination include silane coupling agents, titanate coupling agents, aluminate coupling agents, various silicone oils, fatty acids, fatty acid metal salts, esterified products thereof, rosin acid, and the like. .

  The viscosity of the silicone oil is preferably 500 centistokes or less because it is easy to uniformly adhere to the surface of the external additive particles. More preferably, 300 centistokes or less is more suitable for use, and even more preferably 200 centistokes or less.

  The addition amount of the large-diameter external additive is preferably 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass with respect to 100 parts by mass of toner base particles described later. When the addition amount is less than 0.5 parts by mass, the effect of reducing non-electrostatic adhesion is small, and the effect of improving development and transfer may not be obtained sufficiently. On the other hand, the addition amount is more than 5 parts by mass. Then, the amount of the toner mother particle surface exceeding the amount that can be coated by one layer is exceeded, the coating becomes excessive, and the external additive is transferred to the contact member, which easily causes a secondary failure.

-First inorganic particles (small-diameter external additive)-
The small-diameter external additive used in the present invention has a number average particle diameter of 30 nm or less and a free surface treatment agent amount (that is, free carbon amount) of 2 to 50% by mass. If the amount of the free surface treatment agent is less than 2% by mass, the effect of the toner forming a slow agglomeration with the large diameter external additive cannot be obtained. On the other hand, when it exceeds 50% by mass, the powder agglomeration property of the toner is deteriorated, and the powder transportability, developability and transferability are deteriorated. The amount of the free surface treatment agent is more preferably 20 to 45% by mass, and particularly preferably 35 to 45% by mass.
Further, the smaller the number average particle diameter, the more the contact area with the large-diameter external additive increases, so that the effect can be expected. However, if the thickness is less than 5 nm, the adhesion to the surface of the toner base particles is high, and the toner tends to be buried in the toner surface due to stress in the developing machine, and there is a concern that the contact opportunity with the large-diameter external additive expected in the present invention may be reduced. The number average particle diameter is more preferably 20 nm or less, and particularly preferably 15 nm or less.

Here, a method for measuring the amount of the free surface treatment agent will be described.
2 g of toner is added to 40 ml of a 0.2% by mass surfactant (polyoxyethylene (10) octylphenyl ether having a polyoxyethylene polymerization degree of 10 manufactured by Wako Pure Chemical Industries, Ltd.), and the toner gets wet with the aqueous solution. Disperse sufficiently. In this state, an ultrasonic homogenizer US300T (manufactured by Nippon Seiki Seisakusho) was used, and ultrasonic vibration with an output of 20 W and a frequency of 20 kHz was applied for 1 minute to desorb the additive particles. Thereafter, the toner is separated under conditions of 3000 rpm × 7 minutes through a 50 ml centrifuge with a sedimentation tube (compact cooling high-speed centrifuge Model M160 IV, manufactured by Sakuma Seisakusho Co., Ltd.), and the supernatant liquid is separated into a membrane filter (Nippon Millipore (Japan Millipore ( After suction filtration with FHLP02500), the filtrate is further suction filtered with a membrane filter having a pore size of 0.22 μm (GSEP047SO) and a pore size of 0.025 μm (VSWP02500), and the furnace liquid is dried. NMR measurement of the dried residue can be performed under specified conditions (described in detail later), and the amount of the free surface treatment agent can be converted from the peak of the free treatment agent. In addition, when the sample amount required for the measurement could not be collected at one time, the same operation was repeated until the sample amount required for the measurement could be recovered.

The said small diameter external additive used for this invention can be manufactured by making a surface treatment agent react with a core material.
As a manufacturing method of the small-diameter external additive, a gas phase method, a wet manufacturing method including a sol-gel manufacturing method, or the like can be employed. Examples of the surface treatment method include a dry method such as a spray drying method in which a treatment agent or a solution containing a treatment agent is sprayed on particles suspended in a gas phase, or particles in a solution containing the treatment agent. Examples include a wet method of dipping and drying, and a mixing method of mixing the processing agent and particles with a mixer. Further, a step of washing with a solvent after the surface treatment to remove the residual treatment agent or low-boiling residue may be added. The production method is not particularly limited to the above method.

  Examples of the material used for the core material include silica, titania, metatitanic acid, zinc oxide, zirconia, magnesia, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide, and strontium titanate. Among them, silica is preferable. . Silica has higher liberty from the toner surface than titania and alumina, and the chance of contact with a large-diameter external additive increases, so that the effect of the present invention tends to be remarkable. As the core material, the above materials may be used alone or in combination.

Examples of the surface treatment agent include general coupling agents, silicone oils, fatty acids, fatty acid metal salts, etc. Among them, silicone oils and long chain silane coupling agents (carbon number of alkyl chain such as decylsilane) Is preferably 10 or more). As the surface treating agent, the above materials may be used alone or a plurality of materials including the above materials may be used in combination.
The amount of the free surface treatment agent described above can be controlled by adjusting the amount of the surface treatment agent added.

  The addition amount of the small-diameter external additive obtained as described above in the toner is preferably 0.3 to 10% by mass, and preferably 0.3 to 2% by mass with respect to the toner described later. Is more preferable. By being in the said range, the removal property of the discharge product which is the effect of this invention can be achieved favorably.

  The external additives (large particle and small particle) according to the present invention obtained as described above are added and mixed in the toner. Examples of the mixing method include a V-type blender, a Henschel mixer, and a ready. It can be carried out by a known mixer such as a Gemixer.

-Other external additives-
Furthermore, various other additives may be added to the electrostatic latent image developing toner of the present invention as required. Examples of these additives include other fluidizing agents, cleaning aids such as polystyrene particles, polymethyl methacrylate particles, and polyvinylidene fluoride particles, or transfer aids.
When the external additive (including large-sized particles and small-sized particles) and other additives are externally added to the toner, they may be added and mixed simultaneously or stepwise. Moreover, it does not matter even if it goes through a sieving process after external addition mixing.

(Toner mother particles)
The toner base particles used in the present invention can be produced from materials such as a binder resin, a colorant, and a release agent, and a charge control agent and the like may be added as necessary.
-Binder resin-
Examples of the binder resin used in the present invention include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate. , Α-methylene aliphatic monocarboxylic such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Examples of homopolymers and copolymers of acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl butyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene. -Maleic anhydride copolymer, polyethylene, polypropylene and the like. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

-Colorant-
Examples of the colorant used in the present invention include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green. Oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

-Release agent-
Typical examples of the release agent used in the present invention include low molecular polyethylene, low molecular polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

-Charge control agent-
As the charge control agent to be added as necessary, known ones can be used, but an azo metal complex compound, a metal complex compound of salicylic acid, and a resin type charge control agent containing a polar group should be used. Can do.

(Manufacture of toner for developing electrostatic latent images)
The method for producing the toner of the present invention preferably satisfies a range of a preferable average shape factor SF1 described below and a preferable range of a particle diameter described below, but is not particularly limited by the manufacturing method, and a known method is used. Can be used.
First, toner base particles containing a binder resin, a colorant, a release agent, and the like are prepared using the following method. For example, a binder resin, a colorant, a release agent, and a kneading and pulverizing method in which a charge control agent and the like are further kneaded, pulverized, and classified as necessary. Method of changing shape by thermal energy, emulsion polymerization of polymerizable monomer of binder resin, dispersion formed, dispersion of colorant, release agent, and charge control agent as required Are mixed, agglomerated, and heat-fused to obtain toner mother particles, an emulsion polymerization aggregation method, a polymerizable monomer, a colorant, and a release agent for obtaining a binder resin, and a charge control agent as required Suspension polymerization method in which solution such as suspension is polymerized by suspending in aqueous solvent, particle shape obtained by suspension polymerization method is changed by mechanical impact force or thermal energy, binder resin, coloring Suspension agent, release agent, and if necessary, charge control agent solution in aqueous solvent and granulate Solution suspension method can be used. In addition, a manufacturing method may be performed in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to give a core-shell structure.
Further, the toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  Next, external additives including the first inorganic particles (small-diameter external additive) and the second inorganic particles (large-diameter external additive) are externally added. As described above, the external additive is added by adding the external additive to the toner base particles obtained as described above, for example, using a known mixer such as a V-type blender, a Henschel mixer or a Redige mixer. The method of mixing is mentioned.

As the electrostatic latent image developing toner of the present invention, one having an average shape factor SF1 in the range of 127 to 150 (that is, substantially spherical shape) is used because it is superior in terms of both transferability and toner cleaning properties. More preferably, the range of 130-140 is more preferable.
The average shape factor SF1 is obtained by the following formula (1).
SF1 = (ML ² / A) × (π / 4) × 100 (1)
In Expression (1), ML represents the maximum toner length, A represents the projected area of the toner, and SF1 = 100 in the case of a true sphere. A specific method for obtaining the shape factor will be described later.

The volume average particle size of the toner of the present invention is preferably 3 to 6 μm, more preferably 5 to 6 μm, from the viewpoints of good developability, transferability, and high-quality images.
A method for measuring the volume average particle diameter of the toner will be described later.

Further, the toner for developing an electrostatic latent image of the present invention obtained from the above preferably has good powder characteristics as the toner, preferably has a powder flowability of 5 to 30%, and 5 to 15 % Is more preferable. The powder flowability is in the above range, so that the replenishment from the toner cartridge to the developing machine, the mixing ability of the replenished toner and the developer is performed well, and the good developability, chargeability, and transfer that do not change with time. Sex can be maintained. Therefore, it is preferable in terms of achieving improvement in image carrier scratches and maintenance of cleaning properties without deteriorating other characteristics.
As a method for controlling the powder fluidity within the above range, a method using the above-mentioned monodispersed spherical silica as the second inorganic particles (large-diameter external additive) can be cited as a good control method.

[Developer for electrostatic latent image development]
The electrostatic latent image developing developer of the present invention (hereinafter sometimes simply referred to as “developer”) is a one-component developer composed of the toner, but two-component development in which the toner is added to a carrier. Any of the agents may be used.

(Carrier)
As the carrier used in the present invention, a resin-coated carrier having a resin coating layer in which a conductive material is dispersed and contained on a core material is preferably used. When spherical toner is used as the toner base particles, the packing property is inevitably increased at the conveyance restriction portion in the developing device, and accordingly, a strong force is applied not only to the toner surface but also to the carrier. Therefore, by including a conductive material dispersed in the resin coating layer of the carrier, even if the resin coating layer is peeled off, it is possible to maintain high image quality over the long term without greatly changing the volume specific resistance of the carrier. can do.

Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to adjust the volume resistivity using the magnetic brush method, a magnetic material is used. Preferably there is.
The average particle diameter of the core material is generally 10 to 500 μm, preferably 30 to 100 μm.

  The matrix resin used for the resin coating layer is polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer. , Styrene-acrylic acid copolymer, straight silicone resin composed of organosiloxane bond or modified product thereof, fluororesin, polyester, polyurethane, polycarbonate, phenol resin, amino resin, melamine resin, benzoguanamine resin, urea resin, amide resin, epoxy Although resin etc. can be illustrated, it is not limited to these.

Examples of the conductive material include metals such as gold, silver, and copper, and titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black, but are not limited thereto. It is not a thing.
The content of the conductive material is preferably 1 to 50 parts by mass and more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the matrix resin.

  As a method for forming a resin coating layer on the surface of the carrier core material, a dipping method in which the carrier core material is immersed in a coating layer forming solution containing a matrix resin, a conductive material and a solvent, or a coating layer forming solution is used as the carrier. Spray method for spraying on the surface of the core material, fluidized bed method for spraying the coating layer forming solution in a state where the carrier core material is suspended by fluid air, mixing the carrier core material and the coating layer forming solution in a kneader coater, The kneader coater method etc. which remove a solvent are mentioned.

  The solvent used in the coating layer forming solution is not particularly limited as long as it dissolves the matrix resin. For example, aromatic hydrocarbons such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. , Ethers such as tetrahydrofuran and dioxane can be used.

  The average film thickness of the resin coating layer is usually 0.1 to 10 μm, but in the present invention, it is preferably in the range of 0.5 to 3 μm in order to develop a stable volume resistivity of the carrier over time. .

The volume resistivity of the carrier produced as described above is 10 ⁶ to 10 ¹⁴ in the range of 10 ³ to 10 ⁴ V / cm corresponding to the upper and lower limits of a normal development contrast potential in order to achieve high image quality. It is preferably Ωcm. If the volume resistivity of the carrier is less than 10 ⁶ Ωcm, the reproducibility of fine lines is poor, and toner fog is likely to occur on the background due to charge injection. Further, if the volume specific resistance of the carrier is larger than 10 ¹⁴ Ωcm, reproduction of black solid and halftone becomes worse. In addition, the amount of carrier transferred to the image carrier increases, and the image carrier is easily damaged.

  The content ratio of the toner and the carrier contained in the developer of the present invention is preferably in the range of 2:98 to 15:85, and more preferably in the range of 3:97 to 10:90.

<Image forming apparatus>
The image forming apparatus of the present invention includes an electrostatic latent image forming unit that forms a latent image on an image carrier (hereinafter, also referred to as “photosensitive member”), and the latent image is developed with toner to be visible. A developing unit that forms an image; a transfer unit that transfers the visible image to a recording medium; and a cleaning unit that removes toner remaining on the image carrier after the transfer using a cleaning blade. Become. The toner for forming an electrostatic latent image described above is used as the toner, and the pressing pressure of the cleaning blade against the image carrier is 1.0 × 10 ^{−2 to} 3.5 × 10 ⁻² mN / cm. It is characterized by that.
Hereinafter, the image forming apparatus of the present invention will be described in detail with a focus on a photoreceptor (image carrier) and a cleaning blade.

(Photoconductor)
The photoreceptor (image carrier) used in the image forming apparatus of the present invention is not particularly limited, and a conventionally known photoreceptor can be used. For example, an organic photosensitive layer is formed on a conductive support. A photoreceptor is preferably used. The organic photosensitive layer includes at least a charge generation layer formed by binding a charge generation material with a suitable resin as a binder (binder resin), and a charge transport layer in which the charge transport material is dispersed or dissolved in the binder resin. In addition, an undercoat layer, a protective layer, and the like can be formed as necessary.
Hereinafter, a photoreceptor having a charge generation layer, a charge transport layer, and a protective layer on a conductive support will be described.

-Conductive support:
Any conductive support may be used as long as it is conventionally used.
For example, metals such as aluminum, nickel, chromium, stainless steel; plastic films provided with thin films such as aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, ITO; And paper coated with or impregnated with an agent, plastic film, and the like. Furthermore, if necessary, the surface of the conductive support can be subjected to various treatments within a range that does not affect the image quality. For example, surface anodization treatment, chemical treatment or coloring treatment, or irregular reflection treatment such as graining or liquid honing can be performed.

An undercoat layer may be formed on the surface of the conductive support as desired.
The undercoat layer is an acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate In addition to polymer resin compounds such as maleic anhydride resin, silicone resin, phenol-formaldehyde resin, and melamine resin, there are organometallic compounds containing zirconium, titanium, aluminum, manganese, silicon atoms, and the like. These compounds can be used alone or as a mixture or polycondensate of a plurality of compounds.
The thickness of the undercoat layer is preferably 0.1 to 50 μm, and more preferably 0.2 to 30 μm.

-Charge generation layer:
The charge generation layer can be formed on the conductive support (when the undercoat layer is formed, on the undercoat layer).
As the charge generation material contained in the charge generation layer, phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine can be used. In particular, Bragg for CuKα characteristic X-rays Chlorogallium phthalocyanine crystal having strong diffraction peaks at angles of at least 7.4 °, 16.6 °, 25.5 ° and 28.3 ° of the angle (2θ ± 0.2 °), Bragg angle relative to CuKα characteristic X-ray (2θ Metal-free phthalocyanine crystal having strong diffraction peaks at least 7.7 °, 9.3 °, 16.9 °, 17.5 °, 22.4 ° and 28.8 ° of ± 0.2 °, CuKα characteristics Bragg angle (2θ ± 0.2 °) to X-ray of at least 7.5 °, 9.9 °, 12. Hydroxygallium phthalocyanine crystal having strong diffraction peaks at °, 16.3 °, 18.6 °, 25.1 ° and 28.3 °, Bragg angle (2θ ± 0.2 °) to CuKα characteristic X-ray of at least 9 Titanyl phthalocyanine crystals having strong diffraction peaks at .6 °, 24.1 ° and 27.2 ° can be used.

In addition, as the charge generation material, a quinone pigment, a perylene pigment, an indigo pigment, a bisbenzimidazole pigment, an anthrone pigment, a quinacridone pigment, and the like can be used.
The above charge generation materials can be used alone or in admixture of two or more.

Examples of the binder resin in the charge generation layer include the following. That is, polycarbonate resin such as bisphenol A type or bisphenol Z type, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer Examples thereof include a coalescing resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, phenol-formaldehyde resin, poly-N-vinylcarbazole and the like. These binder resins can be used alone or in combination of two or more.
The compounding ratio (mass ratio) of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10.

  As a solvent used for dispersion of the charge generating material, a solvent capable of dissolving the binder resin can be appropriately selected. As a method for dispersing the charge generating material in the resin, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a high pressure homogenizer can be used.

  Examples of the coating method include dip coating, push-up coating, spray coating, roll coater coating, and gravure coater coating. The thickness of the charge generation layer is generally set in the range of 0.01 to 5 μm, preferably 0.05 to 2.0 μm.

-Charge transport layer:
The charge transport layer can be formed on the charge generation layer.
The charge transport layer may contain inorganic particles. The content of the inorganic particles in the charge transport layer is suitably from 0.1 to 30% by weight, particularly preferably from 1 to 20% by weight, based on the total amount of the charge transport layer. If the content is less than 1% by mass, the modification effect due to the dispersion of inorganic particles is not sufficient. On the other hand, if the content exceeds 30% by mass, the residual potential increases due to repeated use.

Examples of inorganic particles include alumina, silica, titanium oxide, zinc oxide, cerium oxide, zinc sulfide, magnesium oxide, copper sulfate, sodium carbonate, magnesium sulfate, potassium chloride, calcium chloride, sodium chloride, nickel sulfate, antimony, and dioxide. Manganese, chromium oxide, tin oxide, zirconium oxide, barium sulfate, aluminum sulfate, silicon carbide, titanium carbide, boron carbide, tungsten carbide, zirconium carbide and the like can be mentioned, and silica is preferably used. These may be used alone or in combination of two or more as required.
The silica particles are preferably produced by chemical flame CVD, and as a specific example, produced by gas phase reaction of chlorosilane gas in a high-temperature flame of oxygen-hydrogen mixed gas or hydrocarbon-oxygen mixed gas. Is preferred.

The inorganic particles are preferably those that have been hydrophobized with a hydrophobizing agent. As the hydrophobizing agent, for example, a siloxane compound, a silane coupling agent, a titanium coupling agent, a polymer fatty acid or a metal salt thereof is used.
Examples of the siloxane compound include dihydroxypolysiloxane and octamethylcyclotetrasiloxane.
Examples of the silane coupling agent include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N -Vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane , Dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, and the like.

  The primary particle size of the inorganic particles is preferably 0.005 to 2.0 μm, and more preferably 0.01 to 1.0 μm, as the number average particle size. If it is less than 0.005 μm, sufficient mechanical strength on the surface of the photoreceptor cannot be obtained, and aggregation during dispersion tends to proceed. If it exceeds 2 μm, the surface roughness of the photoreceptor increases, the cleaning blade is worn and damaged, the cleaning characteristics are deteriorated, and image blurring tends to occur.

Examples of the charge transport material include oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole; 1,3,5-triphenyl-pyrazolin, 1- [ Pyrazoline derivatives such as pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazolin; triphenylamine, tri (p-methylphenyl) aminyl-4-amine, dibenzylaniline Aromatic tertiary amino compounds such as N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine etc .; 3- (4′-dimethylaminophenyl) 1,2,4-triazine derivatives such as -5,6-di- (4'-methoxyphenyl) -1,2,4-triazine; 4-diethylaminobenza Hydrazone derivatives such as rudehydr-1,1-diphenylhydrazone; quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline; benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) benzofuran; p- Α-stilbene derivatives such as (2,2-diphenylvinyl) -N, N-diphenylaniline; enamine derivatives; carbazole derivatives such as N-ethylcarbazole; poly-N-vinylcarbazole and derivatives thereof; Can be mentioned.
In addition, quinone compounds such as chloranil and broanthraquinone; tetraanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; xanthone An electron transport material such as a compound; a thiophene compound; and the like, and a polymer having a group composed of the above-described compound in the main chain or side chain can also be exemplified. These charge transport materials can be used alone or in combination of two or more.

  Examples of the binder resin include an acrylic resin, polyarylate, polyester resin, bisphenol A type or bisphenol Z type polycarbonate resin; polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, and the like. Insulating resins such as polysulfone, polyacrylamide, polyamide, and chlorine rubber; organic photoconductive polymers such as polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene;

The charge transport layer can be formed by applying and drying a solution in which the charge transport material and the binder resin are dissolved in an appropriate solvent.
Examples of the solvent used for forming the charge transport layer include aromatic hydrocarbon solvents such as toluene and chlorobenzene; aliphatic alcohol solvents such as methanol, ethanol and n-butanol; acetone, cyclohexanone and 2-butanone. Ketone solvents such as; halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride; cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether; or a mixed solvent thereof Can be used.

  The blending ratio (mass ratio) of the charge transport material and the binder resin is preferably 10: 1 to 1: 5. As a method for dispersing the inorganic particles in the charge transport layer, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a high-pressure homogenizer, an ultrasonic disperser, a colloid mill, and the like can be used.

Examples of dispersion of the coating liquid for forming the charge transport layer include dispersion of fluorine resin particles when inorganic particles or the charge transport layer is a surface layer in a solution of a binder resin or charge transport material dissolved in the above solvent. The method of doing is mentioned. It is also effective to add a small amount of a dispersion aid in order to improve the dispersion stability of the dispersion and to prevent aggregation during the formation of the coating film.
Examples of the dispersion aid include fluorine-based surfactants, fluorine-based polymers, silicone-based polymers, and silicone oils. From the viewpoint of high sensitivity and reduction in residual potential during repeated use, 0.1 to 1.0. A mass% fluorine-based graft polymer is preferably used.

  Examples of the coating method include dip coating, push-up coating, spray coating, roll coater coating, and gravure coater coating. The thickness of the charge transport layer is generally 5 to 60 μm, and preferably 10 to 50 μm. The above range is preferably selected from the viewpoint of surface abrasion resistance and charge retention performance. Further, the surface roughness Rz in the case where the charge transport layer is a surface layer is measured by, for example, a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd., JIS-94 standard), and is in the range of 0.01 to 1.0 μm (preferably, 0.1 to 0.8 μm) is preferably selected from the viewpoints of maintaining the transfer performance, the cleaning performance, and both.

・ Protective layer:
The protective layer is an arbitrary layer formed on the charge transport layer, and a conventionally known material can be applied as the composition.
A material in which conductive particles are dispersed in a binder resin, a material in which lubricating particles such as a fluororesin or an acrylic resin are dispersed in a normal charge transport layer material, or a hard coat agent such as silicon or acrylic can be used. However, in order to increase the durability of the photoreceptor, the protective layer preferably contains a resin having a crosslinked structure, and further includes a charge transporting material from the viewpoint of electrical characteristics, image quality maintenance, and the like (charge transporting ability). It is more preferable that the structure unit includes a structural unit having
Various materials can be used for forming the crosslinked structure, but phenolic resins, siloxane resins, urethane resins, epoxy resins, and the like are preferable in terms of characteristics, and those made of phenolic resins or siloxane-based resins are particularly preferable. In addition to the resin having a crosslinked structure, the protective layer includes a binder resin not having a crosslinked structure, conductive particles, and lubricating particles made of a fluororesin or an acrylic resin, if necessary. In forming the protective layer, a hard coat agent such as silicon or acrylic can be used as necessary.
The film thickness is preferably 1 to 50 μm, and the surface roughness Rz is preferably 0.01 to 1.0 μm.

Additives such as antioxidants, light stabilizers, and heat stabilizers in the photosensitive layer for the purpose of preventing deterioration of the photoreceptor due to ozone, oxidizing gas, or light or heat generated when the electrophotographic apparatus is operated. Can be added.
For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds.
Examples of light stabilizers include derivatives such as benzophenone, benzoazole, dithiocarbamate, and tetramethylpipen.
For the purpose of improving the smoothness of the surface, a leveling agent such as silicone oil can be added to the surface layer.

(Cleaning blade)
The cleaning blade used in the image forming apparatus of the present invention is a cleaning blade for pressing the photosensitive member to remove residual toner, and the pressing pressure between the cleaning blade and the image carrier is 1.0 × 10 ^{− 2 to} 3.5 × 10 ⁻² mN / cm. Note that when the pressing pressure is in the above range, there is a problem that the discharge product is not satisfactorily removed at the pressing portion. However, in the image forming apparatus of the present invention using the toner described above, the discharge generation The effect of removing objects is remarkably exhibited.
The pressing pressure will be described later in detail.

  The material of the cleaning blade is not particularly limited as long as it is an elastic body that satisfies the above physical properties, and various elastic bodies can be used. As a specific elastic body, an elastic body such as polyurethane, silicone rubber, nitrile rubber, chloroprene rubber or the like can be used.

Examples of polyurethane elastic bodies include polyurethanes generally synthesized through addition reactions of isocyanates with polyols and various hydrogen-containing compounds.
Examples of the polyol (component) include polyether polyols such as polypropylene glycol and polytetramethylene glycol; polyester polyols such as adipate polyol, polycaprolactam polyol, and polycarbonate polyol.
As the isocyanate (component), aromatic polyisocyanates such as tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, toluidine diisocyanate; hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate Aliphatic polyisocyanates such as, etc. can be used.

By preparing a urethane prepolymer from any of the above polyols and any of the above isocyanates, adding a curing agent thereto, pouring it into a predetermined mold, crosslinking and curing, and then aging at room temperature Can be manufactured.
As the curing agent, a dihydric alcohol such as 1,4-butanediol and a trihydric or higher polyhydric alcohol such as trimethylolpropane or pentaerythritol are usually used in combination.

(Charging device)
In general, the charging device includes a contact-type charging device and a non-contact-type charging device, and is not particularly limited in the present invention, but has excellent charging uniformity and high-speed suitability. It is preferable to use a non-contact type charging device from the viewpoint that the torque at the pressing portion between the cleaning blade and the image carrier is low. The non-contact type charging device has a problem in that a large amount of discharge products such as ozone and NO _x are generated, so that the image flow due to the discharge products is likely to occur. By applying the image forming apparatus, the effect of removing the discharge product is remarkably exhibited.

  Examples of the non-contact charging device include a scorotron and a corotron using corona discharge.

Next, an example of the image forming apparatus of the present invention is shown in FIG. FIG. 1 is a schematic diagram showing an example of an image forming apparatus of the present invention. In the figure, 10 is an image carrier (photoconductor), 12 is a charging roll, 14 is a laser exposure device, 16 is a developing device, and 18 is a developing device. A transfer roll, 19 is a static elimination lamp, 20 is a cleaning blade, and 22 is a fixing roll.
The image forming apparatus shown in FIG. 1 includes a charging roll 12, a laser exposure device 14, a developing device 16, a transfer roll 18, around the photoconductor 10 along the clockwise direction (the direction of arrow A in the figure). A static elimination lamp 19 and a cleaning blade 20 are arranged.

Here, the charging roll 12 uniformly charges the surface of the photoreceptor 10.
On the other hand, the transfer roll 18 is disposed so as to be in contact with the surface of the photoconductor 10, and the paper P can be inserted in the arrow B direction through the contact portion (transfer portion). In addition, a thermal fixing machine including a pair of fixing rolls 22 is disposed on the arrow B direction side with respect to the transfer unit, and the sheet P that has passed through the transfer unit contacts the pair of fixing rolls 22. Part (fixing part) can be inserted in the direction of arrow B.

The image formation by the image forming apparatus shown in FIG. 1 is performed as follows. First, the surface of the photoreceptor 10 is charged by the charging roll 12. Subsequently, the laser exposure device 14 irradiates the surface of the photosensitive member 10 with a laser beam corresponding to the image information to form an electrostatic latent image. Thereafter, the electrostatic latent image is developed by the developing device 16 and a toner image is formed on the surface of the photoreceptor 10. The toner image is transferred to the surface of the paper P by the transfer unit, and is transported to the fixing unit by a transport unit (not shown), and then the paper P on which the toner image is transferred is heated and pressed to form an image on the surface. It is formed.
On the other hand, after the transfer, the surface of the photoconductor 10 is neutralized by the static elimination lamp 19, and the cleaning blade 20 is used to remove other deposits such as residual toner and discharge products adhering to the surface of the photoconductor 10 after transfer. Prepare for the next image formation.

Next, FIG. 2 shows a state where the cleaning blade is pressed against the surface of the photoreceptor. In FIG. 2, 2 is a cleaning blade, and 1 is a photoreceptor that rotates in the direction of arrow A. The cleaning blade 2 is pressed against the surface of the photoreceptor 1 by a holding member 3, for example.
In the present invention, the pressing pressure (pressing linear pressure) of the cleaning blade 2 to the photosensitive member 1 is 1.0 × 10 ^{−2 to} 3.5 × 10 ⁻² N / mm, and further 3.0 ×. More preferably, it is 10 ^{−2 to} 3.5 × 10 ⁻² N / mm.
When cleaning is performed with a low pressing pressure such as the above range, the discharge product removal performance deteriorates, but the effect of removing the discharge product can be achieved by applying the image forming apparatus of the present invention using the above-described toner. Can be remarkably exhibited.

  Further, the amount of biting of the cleaning blade 2 (the amount of deformation of the cleaning blade 2 caused by being pressed against the surface of the photoreceptor 1, more specifically, d in FIG. 2, which should bite when the cleaning blade 2 is not deformed). Is preferably 0.7 to 1.5 mm, and more preferably 0.9 to 1.1 mm. Further, the pressing angle of the cleaning blade 2 against the photosensitive member 1 (the angle formed between the tangent to the surface of the photosensitive member 1 and the cleaning blade 2) is preferably 5 to 30 °, more preferably 10 to 25 °. More preferred. When the angle is smaller than the above range, the surface of the photoreceptor is bumped and cleaning failure is likely to occur. When the angle is larger, the problem of blade turning may occur.

(Process cartridge)
The image forming apparatus may be an image forming apparatus in which a process cartridge is detachable. Specifically, the process cartridge of the present invention is detachable from the loading portion of the image forming apparatus, and develops a visible image by developing the image carrier and the latent image formed on the image carrier with toner. At least a developing device for forming, and a cleaning device for removing toner remaining on the image carrier using a cleaning blade. The toner has a number average particle size of 30 nm or less and a free surface treatment agent amount of 2 Containing first inorganic particles of ˜50 mass% and second inorganic particles of number average particle size of 80 to 200 nm, and the pressing pressure of the cleaning blade against the image carrier is 1.0 ×. It is a process cartridge characterized by being 10 ^{−2 to} 3.5 × 10 ⁻² mN / cm.

(Image forming method)
The image forming method of the present invention includes an electrostatic latent image forming step of forming a latent image on an image carrier, a developing step of developing the latent image with toner to form a visible image, At least a transfer step for transferring to a recording medium and a cleaning step for removing toner remaining on the image carrier after transfer using a cleaning blade, wherein the toner is free with a number average particle size of 30 nm or less. A first inorganic particle having a surface treatment agent amount of 2 to 50% by mass and a second inorganic particle having a number average particle diameter of 80 to 200 nm, and pressing the cleaning blade against the image carrier The pressure is 1.0 × 10 ^{−2 to} 3.5 × 10 ⁻² mN / cm.
The image forming method of the present invention is preferably carried out using the image forming apparatus of the present invention described above.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In the examples, “parts” and “%” all mean “parts by mass” and “% by mass” unless otherwise specified.

First, the measurement method used in this example will be described.
-Number average particle diameter of external additives-
The measurement was performed using a scanning electron microscope (SEM: S-4700, manufactured by Hitachi, Ltd.). The externally added toner particles are observed with a scanning electron microscope (SEM: S-4700, manufactured by Hitachi, Ltd.) in 100 fields (50000 times), and circular particles corresponding to the image area of each external additive. Were measured at 1000 locations, and the average value was taken as the number average particle size of the external additive. In the case of composite external addition, mapping was performed at an acceleration voltage of 20 kV using an energy dispersive X-ray analyzer EMAX model 6923H (manufactured by HORIBA) attached to the electron microscope S4100, and the type of external additive was determined.

-Amount of free surface treatment agent for external additives-
2 g of toner is added to 40 ml of an aqueous solution of 0.2% surfactant (polyoxyethylene (10) octylphenyl ether having a polyoxyethylene polymerization degree of 10 manufactured by Wako Pure Chemical Industries, Ltd.) so that the toner gets wet with the aqueous solution. Disperse thoroughly. In this state, an ultrasonic homogenizer US300T (manufactured by Nippon Seiki Seisakusho) was used, and ultrasonic vibration with an output of 20 W and a frequency of 20 kHz was applied for 1 minute to desorb the additive particles. Thereafter, the toner is separated under conditions of 3000 rpm × 7 minutes through a 50 ml centrifuge with a sedimentation tube (compact cooling high-speed centrifuge Model M160 IV, manufactured by Sakuma Seisakusho Co., Ltd.), and the supernatant liquid is separated into a membrane filter (Nippon Millipore (Japan Millipore ( After removal with FHLP02500), the membrane was further removed with a membrane filter having a pore size of 0.22 μm (GSEP047SO) and a pore size of 0.025 μm (VSWP02500), and then the furnace liquid was dried. If the sample amount required for measurement could not be recovered, the same operation was repeated until the sample amount required for measurement could be recovered. NMR measurement was performed using 10 mg of the dried residue.
Proton NMR was measured using AL-400 (magnetic field 9.4T (H nucleus 400 MHz)) manufactured by JEOL. A sample tube (5 mmφ) made of zirconia is filled with a sample, a deuterated chloroform solvent, and TMS as a reference substance. This sample tube is set, and for example, measurement is performed at a frequency: Δ87 kHz / 400 MHz (= Δ20 ppm), measurement temperature: 25 ° C., integration number: 16 times, resolution 0.24 Hz (about 32000 points), free surface treatment agent It converted into the amount of free surface treating agents using the analytical curve from the peak intensity of origin. For example, when dimethyl silicone oil is used as the free surface treatment agent, NMR measurement is performed on the untreated external additive base material and dimethyl silicone oil (shake about 5 levels), and the amount of free surface treatment agent And a calibration curve of NMR peak intensity.

-Toner average shape factor SF1-
SF1 is obtained by the following formula (1).
SF1 = (ML ² / A) × (π / 4) × 100 (1)
In Expression (1), ML represents the maximum toner length, A represents the projected area of the toner, and SF1 = 100 in the case of a true sphere. As a specific method for obtaining the shape factor, a toner image is taken from an optical microscope into an image analyzer (LUZEX III: manufactured by Nireco Corporation), an equivalent circle diameter is measured, and the maximum length and area are calculated. This was done by determining the value of SF1 in the above formula for each particle.

-Volume average particle diameter of toner-
The volume average particle size (cumulative volume average particle size D50) of the toner was measured using Coulter Multisizer II (Beckman-Coulter) and the electrolyte using ISOTON-II (Beckman-Coulter). In the measurement, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant (sodium alkylbenzenesulfonate) as a dispersant, and this is added to 100 to 150 ml of an electrolytic solution. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a diameter in the range of 2 to 60 μm is measured using a 100 μm aperture as the aperture diameter by Coulter Multisizer II. . The number of particles to be sampled is 50,000. For the particle size range (channel) divided on the basis of the particle size distribution measured in this way, the cumulative distribution of the volume is drawn from the smaller diameter side, and the particle size that becomes 50% cumulative is the cumulative volume average particle size D50. Defined.

-Toner powder flowability-
Using a powder characteristic combination measuring device (powder tester PT-D) manufactured by Hosokawa Micron Corporation, sieves having openings of 53 μm, 45 μm, and 38 μm were arranged in series from the upper stage, and 2 g of accurately weighed on the 53 μm sieve. The toner was added, and the vibration was applied for 90 seconds with an amplitude of 1 mm, and the toner mass on each sieve after vibration was measured, and calculated using the following formula. In addition, the sample used what was left to stand in the environment of 25 degreeC / 50% RH for about 24 hours, and the measurement was performed in the environment of 25 degreeC / 50% RH.
(Normal temperature cohesion) = (W ₅₃ × 50) + (W ₄₅ × 30) + (W ₃₈ × 10) (2)
(W ₅₃ represents the mass of the developer remaining on the sieve having an aperture of 53 μm, W ₄₅ represents the mass of the developer remaining on the sieve having an aperture of 45 μm, and W ₃₈ represents a sieve having an aperture of 38 μm. This represents the mass of the developer remaining on the top.)

<Production of first inorganic particles (1)>
100 parts of hydrophilic silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.) prepared by a gas phase method is dispersed in 1000 parts of a toluene solution, 30 parts of decyltrimethoxysilane (KBM-3103, manufactured by Shin-Etsu Silicone), dimethyl silicone oil ( 30 parts of KF-96 (50 cs, manufactured by Shin-Etsu Silicone) were added, and after applying ultrasonic waves, toluene was distilled off with an evaporator, and heating was further performed at 150 ° C. for 1 hour, followed by pulverization. First inorganic particles (1), which are small diameter external additives having an average particle diameter of 12 nm, were obtained. The amount of the free surface treatment agent is shown in Table 1 below.

<Preparation of first inorganic particles (2)>
100 parts of hydrophilic silica (AEROSIL 50, manufactured by Nippon Aerosil Co., Ltd.) prepared by a gas phase method is dispersed in 1000 parts of a toluene solution, and 40 parts of decyltrimethoxysilane (KBM-3103, manufactured by Shin-Etsu Silicone) is added thereto to ultrasonically After applying toluene, toluene was distilled off with an evaporator, and after heating at 150 ° C. for 1 hour, the mixture was pulverized to obtain the first inorganic particles (2), which are small diameter external additives having a number average particle diameter of 30 nm. Obtained. The amount of the free surface treatment agent is shown in Table 1 below.

<Production of first inorganic particles (3)>
100 parts of hydrophilic titania (F-6, manufactured by Showa Denko KK) prepared by a gas phase method is dispersed in 1000 parts of a toluene solution, and 120 parts of carbinol-modified silicone oil (X-22-170DX, manufactured by Shin-Etsu Silicone) is dispersed. Toluene was distilled off with an evaporator after being added and subjected to ultrasonic waves, and further heated at 150 ° C. for 1 hour, and then pulverized to be a first inorganic additive as a small diameter external additive having a number average particle diameter of 15 nm. Particles (3) were obtained. The amount of the free surface treatment agent is shown in Table 1 below.

<Production of first inorganic particles (4)>
100 parts of hydrophilic titania (F-6, manufactured by Showa Denko KK) prepared by a gas phase method is dispersed in 1000 parts of a toluene solution, and 12 parts of dimethyl silicone oil (KF-96 (50 cs), manufactured by Shin-Etsu Silicone) is added. Then, after applying ultrasonic waves, toluene is distilled off by an evaporator, and further heating is performed at 150 ° C. for 1 hour, followed by pulverization, and first inorganic particles which are small diameter external additives having a number average particle diameter of 15 nm. (4) was obtained. The amount of the free surface treatment agent is shown in Table 1 below.

<Preparation of inorganic particles (5) for comparison>
100 parts of hydrophilic silica (OX50, manufactured by Nippon Aerosil Co., Ltd.) prepared by a gas phase method is dispersed in 1000 parts of a toluene solution, and 44 parts of methacryl-modified silicone oil (X-22-174DX, manufactured by Shin-Etsu Silicone) is added. After applying ultrasonic waves, toluene was distilled off with an evaporator, and heating was further performed at 150 ° C. for 1 hour, followed by pulverization to obtain inorganic particles (5) having a number average particle diameter of 40 nm. The amount of the free surface treatment agent is shown in Table 1 below.

<Production of inorganic particles (6) for comparison>
100 parts of hydrophilic silica (AEROSIL200, manufactured by Nippon Aerosil Co., Ltd.) prepared by a gas phase method is dispersed in 1000 parts of a toluene solution, and 75 parts of decyltrimethoxysilane (KBM-3103, manufactured by Shin-Etsu Silicone) is added to ultrasonic waves. After applying toluene, toluene was distilled off with an evaporator, and heating was further performed at 150 ° C. for 1 hour, followed by pulverization to obtain inorganic particles (6) having a number average particle diameter of 12 nm. The amount of the free surface treatment agent is shown in Table 1 below.

<Preparation of inorganic particles (7) for comparison>
100 parts of hydrophilic silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) prepared by a gas phase method is dispersed in 1000 parts of a toluene solution, and 42 parts of carbinol-modified silicone oil (X-22-170DX, manufactured by Shin-Etsu Silicone) is added. After applying ultrasonic waves, toluene was distilled off with an evaporator, and heating was further performed at 150 ° C. for 1 hour, followed by pulverization to obtain inorganic particles (7) having a number average particle diameter of 12 nm. The amount of the free surface treatment agent is shown in Table 1 below.

<Production of second inorganic particles (A)>
The silica sol obtained by the sol-gel method was treated with HMDS (hexamethyldisilazane), dried and pulverized. Disperse 100 parts of this HMDS-treated silica sol in 1000 parts of a toluene solution, add 3 parts of dimethyl silicone oil (KF-96 (50 cs), manufactured by Shin-Etsu Silicone), apply ultrasonic waves, and then distill off the toluene with an evaporator. Further, after heating at 150 ° C. for 1 hour, the mixture is pulverized and is a large-diameter external additive having a sphericity Ψ = 0.80 and a number average particle diameter D ₅₀ = 130 nm (standard deviation = 25 nm). Second inorganic particles (A) were obtained.

<Preparation of second inorganic particles (B)>
The silica sol obtained by the sol-gel method was subjected to HMDS treatment, dried and pulverized. Disperse 100 parts of this HMDS-treated silica sol in 1000 parts of a toluene solution, add 3 parts of dimethyl silicone oil (KF-96 (50 cs), manufactured by Shin-Etsu Silicone), apply ultrasonic waves, and then distill off the toluene with an evaporator. Further, after heating at 150 ° C. for 1 hour, the mixture was pulverized to obtain a second external additive having a large diameter, Ψ = 0.85, number average particle diameter D ₅₀ = 100 nm (standard deviation = 20 nm). Inorganic particles (B) were obtained.

<Production of second inorganic particles (C)>
Silica sol obtained by the sol-gel method is subjected to HMDS treatment, dried and pulverized to give a second inorganic additive which is a large-diameter external additive with Ψ = 0.75 and number average particle diameter D ₅₀ = 140 nm (standard deviation = 28 nm). Particles (C) were obtained.

[Production of toner]
<Preparation of resin particle dispersion>
・ Styrene ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 296 parts ・ N-butyl acrylate ・ ・ ・ ・ 104 parts ・ Acrylic acid ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ 6 parts ・ Dodecanethiol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 10 parts ・ Divinyl adipate ・ ・ ・ ・ ・ 1.6 parts (Wako Pure Chemical Industries, Ltd. ) Made)
A mixture obtained by mixing and dissolving the above components was mixed with 12 parts of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 8 Ion exchange with 8 parts of ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) dissolved in 610 parts of ion-exchanged water, dispersed in a flask, emulsified, and slowly mixed for 10 minutes. 50 parts of water was added and nitrogen substitution was performed at 0.1 liter / min for 20 minutes. Thereafter, while stirring the inside of the flask, the contents are heated in an oil bath until the content reaches 70 ° C., and emulsion polymerization is continued for 5 hours, and a resin particle dispersion liquid having an average particle size of 200 nm and a solid content concentration of 40% ( 1) was prepared. When a portion of the dispersion was left in an oven at 100 ° C. to remove moisture, DSC (differential scanning calorimeter) measurement was performed. The glass transition point was 53 ° C. and the weight average molecular weight was 32,000. Met.

<Preparation of Colorant Dispersion (Y)>
・ C. I. Pigment Yellow 74 (monoazo pigment) ... 100 parts (Daiichi Seika Co., Ltd .: Seika First Yellow 2054)
・ Anionic surfactant (Neogen RK: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ・ ・ ・ 10 parts ・ Ion-exchanged water ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・... 490 parts The above components were mixed and dissolved, and dispersed for 10 minutes using a homogenizer (manufactured by IKA: Ultra Tarrax) to prepare a colorant dispersant (Y).

<Preparation of Colorant Dispersion (M)>
The colorant is C.I. I. A colorant dispersion (M) was prepared in the same manner as the colorant dispersion (Y) except that it was changed to CI Pigment Red 122 (quinacridone pigment: manufactured by Dainichi Seika Co., Ltd .: Chromofine Magenta 6887).

<Preparation of Colorant Dispersion (C)>
The colorant is C.I. I. A colorant dispersion liquid (C) was prepared in the same manner as the colorant dispersion liquid (Y) except that it was changed to Pigment Blue 15: 3 (phthalocyanine pigment: manufactured by Dainichi Seika Co., Ltd .: Cyanine Blue 4937).

<Preparation of Colorant Dispersion (K)>
A colorant dispersion (K) was prepared in the same manner as the colorant dispersion (Y) except that the colorant was changed to carbon black (manufactured by Cabot: Regal 330).

<Preparation of release agent particle dispersion>
-Paraffin wax (Nippon Seiwa Co., Ltd .: HNP-9) ... 100 parts-Anionic surfactant (Lion Corp .: Ripar 860K) ... 10 parts-Ion exchange Water ·········································· 390 parts After mixing and dissolving the above components, a homogenizer (manufactured by IKA: Ultra Tarrax) is used. And a dispersion with a pressure discharge type homogenizer to prepare a release agent particle dispersion liquid in which release agent particles (paraffin wax) having an average particle size of 220 nm are dispersed.

(Manufacture of yellow toner base particles)
・ Resin particle dispersion ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 320 parts ・ Colorant dispersion (Y) ・ ・ ・ 80 parts ・ Separation Mold particle dispersion ········· 96 parts · Aluminum sulfate (Wako Pure Chemical Industries, Ltd.) ··· 1.5 parts · Ion-exchanged water ··· ... 1270 parts The above components are contained in a round stainless steel flask with a temperature control jacket, and 5 using a homogenizer (manufactured by IKA, Ultra Turrax T50). After being dispersed at 1,000 rpm for 5 minutes, it was transferred to a flask and left standing at 25 ° C. for 20 minutes with 4 paddles while stirring. Thereafter, the mixture was heated with a mantle heater while stirring and heated at a heating rate of 1 ° C./min until the inside reached 48 ° C., and held at 48 ° C. for 20 minutes. Next, 80 parts of the resin particle dispersion was gradually added and kept at 48 ° C. for 30 minutes, and then a 1N aqueous sodium hydroxide solution was added to adjust the pH to 6.5.
Thereafter, the temperature was raised to 95 ° C. at a rate of 1 ° C./min and held for 30 minutes. A 0.1N nitric acid aqueous solution was added to adjust the pH to 4.8, and the mixture was allowed to stand at 95 ° C. for 2 hours. Thereafter, the 1N aqueous sodium hydroxide solution was further added to adjust the pH to 6.5, and the mixture was allowed to stand at 95 ° C. for 4.7 hours. Thereafter, it was cooled to 30 ° C. at 10 ° C./min.
The resulting toner particle dispersion was filtered, (A) 2,000 parts of ion-exchanged water at 35 ° C. was added to the obtained toner particles, (B) allowed to stand for 20 minutes, and (C) then filtered. After the operations from (A) to (C) were repeated 5 times, the toner particles on the filter paper were transferred to a vacuum dryer and dried at 45 ° C. and 1,000 Pa or less for 10 hours. The reason why the pressure is 1,000 Pa or less is that the above-mentioned toner particles are in a water-containing state, and in the initial stage of drying, the water freezes even at 45 ° C. and then the water sublimates. This is because the pressure does not become constant. However, it was stable at 100 Pa at the end of drying. After returning the inside of the dryer to normal pressure, this was taken out to obtain toner mother particles.
The resulting yellow toner base particles had a volume average particle size D50 of 5.8 μm, a number average particle size distribution index GSDp of 1.23, and a shape factor SF1 of 136.

(Manufacture of magenta toner base particles)
Magenta toner base particles were prepared in the same manner as the yellow toner base particles, except that the colorant dispersion (Y) was changed to the colorant dispersion (M) that is a magenta colorant.
The obtained magenta toner base particles had a volume average particle diameter D50 of 5.6 μm, a number average particle size distribution index GSDp of 1.22, and a shape factor SF1 of 138.

(Manufacture of cyan toner base particles)
Cyan toner base particles were prepared in the same manner as the yellow toner base particles, except that the colorant dispersion (Y) was changed to a colorant dispersion (C) that was a cyan colorant.
The obtained cyan toner base particles had a volume average particle diameter D50 of 5.8 μm, a number average particle size distribution index GSDp of 1.22, and a shape factor SF1 of 134.

(Manufacture of black toner base particles)
Black toner base particles were prepared in the same manner as the yellow toner base particles, except that the colorant dispersion (Y) was changed to the colorant dispersion (K) which is a black colorant.
The obtained black toner base particles had a volume average particle diameter D50 of 5.7 μm, a number average particle size distribution index GSDp of 1.23, and a shape factor SF1 of 140.

<Production of carrier>
・ Ferrite particles (average particle size: 50 μm) 100 parts ・ Toluene 14 parts ・ Styrene-methacrylate copolymer (component ratio: 90/10) 2 parts ・ Carbon black (R330: manufactured by Cabot Corporation) 0.2 part First, ferrite The above components excluding the particles were stirred with a stirrer for 10 minutes to prepare a dispersed coating solution. Next, the coating solution and ferrite particles were placed in a vacuum degassing kneader and stirred at 60 ° C. for 30 minutes. Further, the carrier was obtained by deaeration by depressurization while heating and drying. This carrier had a volume resistivity of 10 ¹¹ Ωcm when an applied electric field of 1000 V / cm was applied.

[Example 1]
100 parts of black, cyan, magenta, and yellow of the toner base particles are each 1.2 parts of the first inorganic particles (1) and 1.5 parts of the second inorganic particles (A) using a Henschel mixer. After blending at 32 m / s × 10 minutes, coarse particles were removed using a sieve of 45 μm mesh to obtain toner of each color. 100 parts of the carrier and 5 parts of each toner are stirred for 20 minutes at 40 rpm using a V-blender, and sieved through a sieve having a 177 μm mesh. The developer (powder fluidity is black, cyan, magenta, yellow, respectively). 12%, 15%, 17%, 15%).

[Example 2]
100 parts of black, cyan, magenta, and yellow of the toner base particles are respectively mixed with 1.0 part of the first inorganic particles (2) and 1.2 parts of the second inorganic particles (B) at a peripheral speed of 32 m using a Henschel mixer. After blending for / s × 10 minutes, coarse particles were removed using a sieve of 45 μm mesh to obtain toner of each color. 100 parts of the carrier and 5 parts of each toner are stirred for 20 minutes at 40 rpm using a V-blender, and sieved through a sieve having a 177 μm mesh. The developer (powder fluidity is black, cyan, magenta, yellow, respectively). 21%, 24%, 27%, 28%).

[Example 3]
100 parts of each of the toner base particles black, cyan, magenta, and yellow were blended with 1.5 parts of the second inorganic particles (C) using a Henschel mixer, and a peripheral speed of 32 m / s × 10 minutes was further blended. After 1.3 parts of inorganic particles (3) were added and blended at a peripheral speed of 20 m / s × 5 minutes, coarse particles were removed using a 45 μm mesh sieve to obtain toner of each color. 100 parts of the carrier and 5 parts of each toner are stirred for 20 minutes at 40 rpm using a V-blender, and sieved through a sieve having a 177 μm mesh. The developer (powder fluidity is black, cyan, magenta, yellow, respectively). 20%, 22%, 23%, 26%).

[Example 4]
Using 100 parts of black, cyan, magenta and yellow of the toner base particles, 1.1 parts of the first inorganic particles (4) and 1 part of the second inorganic particles (A) were used at a peripheral speed of 32 m / s using a Henschel mixer. After blending for 10 minutes, coarse particles were removed using a 45 μm mesh sieve to obtain toner of each color. 100 parts of the carrier and 5 parts of each toner are stirred for 20 minutes at 40 rpm using a V-blender, and sieved through a sieve having a 177 μm mesh. The developer (powder fluidity is black, cyan, magenta, yellow, respectively). 14%, 16%, 17%, 19%).

[Comparative Example 1]
For each of the black, cyan, magenta, and yellow toners of Example 1, this was carried out except that comparative inorganic particles (5) were externally added to the toner base particles instead of the first inorganic particles (1). In the same manner as in Example 1, developer of each color (powder fluidity of 14%, 15%, 17% and 18% for black, cyan, magenta and yellow, respectively) was obtained.

[Comparative Example 2]
For each of the black, cyan, magenta, and yellow toners of Example 1, the procedure was carried out except that comparative inorganic particles (6) were externally added to the toner base particles instead of the first inorganic particles (1). In the same manner as in Example 1, developer of each color (powder fluidity: black, cyan, magenta, yellow, 30%, 35%, 36%, 38%, respectively) was obtained.

[Comparative Example 3]
For each of the black, cyan, magenta, and yellow toners of Example 1, this was carried out except that comparative inorganic particles (7) were externally added to the toner base particles instead of the first inorganic particles (1). In the same manner as in Example 1, developers of each color (powder fluidity of 15%, 17%, 20%, and 22% for black, cyan, magenta, and yellow, respectively) were obtained.

(Production of photosensitive drum)
To 170 parts of n-butyl alcohol in which 4 parts of polyvinyl butyral resin (S-REC BM-S, manufactured by Sekisui Chemical Co., Ltd.) was dissolved, 30 parts of an organic zirconium compound (acetylacetone zirconium butyrate) and an organic silane compound (γ-aminopropyltrimethoxy) 3 parts of silane) was added, mixed and stirred to obtain a coating solution for forming an undercoat layer. This coating solution is dip-coated on an aluminum support having an outer diameter of 60 mm roughened by a honing treatment, air-dried at room temperature for 5 minutes, and then the support is heated to 50 ° C. for 10 minutes. It was placed in a constant temperature and humidity chamber at 50 ° C. and 85% RH (dew point 47 ° C.), and a humidification hardening acceleration treatment was performed for 20 minutes. Then, it put in the hot air dryer and dried for 10 minutes at 170 degreeC, and formed the undercoat layer.

  Using a gallium chloride phthalocyanine as a charge generation material, a mixture of 15 parts, 10 parts of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide) and 300 parts of n-butyl alcohol was mixed with a sand mill. Time dispersed. The obtained dispersion was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm.

  Next, 40 parts of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine and 60 parts of bisphenol Z polycarbonate resin (viscosity average molecular weight 40,000) were added to 235 parts of tetrohydrofuran and monochlorobenzene. A coating solution obtained by sufficiently dissolving and mixing in 100 parts was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 20 μm.

Furthermore, the constituent materials shown below were dissolved in 5 parts of isopropyl alcohol, 3 parts of tetrahydrofuran and 0.3 part of distilled water, and 0.5 parts of ion exchange resin (Amberlyst 15E: manufactured by Rohm and Haas) was added. The hydrolysis was carried out for 24 hours by stirring at room temperature.
(Constituent materials)
・ Compound 1 shown below 2.0 parts ・ Methyltrimethoxysilane 2.0 parts ・ Tetramethoxysilane 0.5 part ・ Colloidal silica 0.3 part ・ Fluorine graft polymer (ZX007C: manufactured by Fuji Kasei) 0.5 part

  0.1 parts of aluminum trisacetylacetonate (Al (aqaq) 3) and 3,5-di-t-butyl-4-hydroxytoluene (BHT) are obtained by filtering and separating the ion exchange resin from the hydrolyzed product. 0.4 parts is added, and this coating solution is applied onto the charge transport layer by a ring-type dip coating method, air-dried at room temperature for 30 minutes, cured by heat treatment at 150 ° C. for 1 hour, and a film thickness of about A 3 μm protective layer was formed. This is defined as (photosensitive drum I). The outermost surface of the photosensitive drum I is constituted by a protective layer containing a siloxane resin having a crosslinked structure, and durability is enhanced.

(Evaluation of image quality)
Image forming apparatus (Fuji Xerox Co., Ltd., Docu Center Color 500, cleaning blade pressing pressure to photoconductor 3.5 × 10 ⁻² mN / m, blade biting amount 1.1 mm, cleaning blade pressing angle to photoconductor Was subjected to an image formation test using the developers obtained in Examples and Comparative Examples, using a modified machine in which the photosensitive member was changed to the above (Photosensitive drum I).

First, an image forming apparatus in which black, cyan, magenta, and yellow color developers were set was allowed to stand overnight in an environment of an air temperature of 10 ° C. and a humidity of 75%, and then a running test for 20,000 sheets was performed in a color mode. Next, the image forming apparatus was left for a day and night in an environment of an air temperature of 40 ° C. and a humidity of 75%, and then a running test of 20,000 sheets was performed in the color mode. After that, the image was left for a whole day and night in an environment of a temperature of 40 ° C. and a humidity of 75%, and 10 images were output in the color mode. Note that “Electrophotographic Society of Japan Test Chart No. 5-1” was used for the color mode image in the running test and image output.
The final 10 output images are visually observed to check for white spots (image flow) and streaks on the white background (if there is streaks, toner cleaning is insufficient. Evaluation of image quality degradation due to something).

1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. The cleaning blade is pressed against the surface of the photoreceptor.

Explanation of symbols

10 Image carrier (photoreceptor)
12 Charging roll 14 Laser exposure device 16 Developer 18 Transfer roll 19 Static elimination lamp 20 Cleaning blade

Claims (2)

An image carrier, an electrostatic latent image forming unit for forming a latent image on the image carrier, a developing unit for developing the latent image with toner to form a visible image, and the visible image on a recording medium. A transfer unit that transfers, and a cleaning unit that removes toner remaining on the image carrier after transfer using a cleaning blade;
The toner includes first inorganic particles having a number average particle diameter of 30 nm or less and a free surface treating agent amount of 2 to 50% by mass, and second inorganic particles having a number average particle diameter of 80 to 200 nm. Contains,
An image forming apparatus, wherein a pressure of pressing the cleaning blade against the image carrier is 1.0 × 10 ^{−2 to} 3.5 × 10 ⁻² mN / cm. It is detachable from the loading part of the image forming apparatus,
An image carrier, a developing device that develops a latent image formed on the image carrier with toner to form a visible image, and a cleaning device that removes toner remaining on the image carrier using a cleaning blade; Having at least
The toner includes first inorganic particles having a number average particle diameter of 30 nm or less and a free surface treating agent amount of 2 to 50% by mass, and second inorganic particles having a number average particle diameter of 80 to 200 nm. Contains,
A process cartridge, wherein the pressure of the cleaning blade against the image carrier is 1.0 × 10 ^{−2 to} 3.5 × 10 ⁻² mN / cm.

Images