JP2012103493A - Image forming apparatus, image forming method, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that achieves suppression of filming, improvement of cleaning performance, and stable supply of protectant; extends the life of an image carrier and peripheral members thereof; and outputs excellent image for a long period.SOLUTION: An image forming apparatus includes at least: an image carrier; developing means for developing an electrostatic latent image formed on the image carrier; and protectant supply means for supplying protectant to the image carrier. Developer included in the developing means contains boron nitride having an average primary particle diameter of 2.0 μm or more and 14.0 μm or less; and the protectant contains at least one kind of fatty acid metal salt and boron nitride having an average primary particle diameter of 0.1 μm or more and 2.0 μm or less.

Description

  The present invention relates to an image forming apparatus, an image forming method, and a process cartridge.

Conventionally, in image formation by electrophotography, a static image is formed on an image carrier such as a photoconductive substance (sometimes referred to as an “electrostatic latent image carrier”, “electrophotographic photosensitive member”, or “photosensitive member”). A latent image is formed by electric charges, and charged toner particles are attached to the electrostatic latent image to form a visible image. The visible image formed by the toner is finally transferred to a recording medium such as paper, and then fixed on the recording medium by heat, pressure, solvent gas, or the like, and becomes an output image.
This electrophotographic image forming method is based on a so-called two-component development method that uses friction charging by stirring or mixing of toner particles and carrier particles by a method of charging toner particles for visualization, and carrier particles. It is roughly classified into a so-called one-component development method in which charge is imparted to toner particles without using the toner. Of these, the one-component development method is more advantageous than the two-component development method in terms of space saving and cost reduction, and is therefore widely used in small printers and facsimiles.

In these electrophotographic image forming apparatuses, the image carrier is generally charged while rotating an image carrier such as a drum shape or a belt shape, regardless of the development method, and the image carrier by laser light or the like. A latent image pattern is formed on the body, which is visualized by a developing device, and further transferred onto a recording medium.
Further, the toner component that has not been transferred remains on the image carrier after the visible image is transferred to the recording medium. If this residual toner component is directly conveyed to the charging step, it may hinder the uniform charging of the image carrier. Generally, the toner remaining on the image carrier after passing through the transfer step. Components are removed in a cleaning process, and the surface of the image carrier is sufficiently cleaned, and then charging is performed.

In recent years, in order to reduce the size and cost of an image forming apparatus using the electrophotographic method, a contact charging method and a proximity charging method are frequently used in the charging step of the image formation. However, since it is difficult to uniformly charge the surface of the image carrier due to slight contact unevenness between the charging member and the surface of the image carrier, a gap variation between the charging member and the surface of the image carrier, etc. An AC superposition charging method in which an alternating current (AC) component is superimposed on a (DC) component has come to be used.
The proximity charging method based on the AC superimposed charging can realize a reduction in size and image quality of the apparatus, and at the same time, can keep the charging member and the image carrier in a non-contact state while maintaining charging uniformity. Deterioration can be suppressed.
However, when the image carrier is an organic photoreceptor (OPC), the energy of the AC superimposed charging cuts the resin chain on the surface of the image carrier and reduces the mechanical strength. It was found that wear was accelerated significantly. Further, since the AC superimposed charging activates the surface of the image carrier, there is a problem that the adhesion between the surface of the image carrier and the toner is increased, and the cleaning performance for the image carrier is lowered.
On the other hand, since the colorization of output images has progressed recently, development has been progressing in the direction of toner particle size reduction and circularization to improve image quality and stabilize image quality. In the image forming method, the problem with respect to cleaning is increasing. In order to clean such toner, it may be a countermeasure to increase the rubbing force of the cleaning member against the image carrier as compared with the conventional case, but stress due to friction in the cleaning process causes the image carrier to wear, Furthermore, there is a problem that the cleaning member is deteriorated quickly.
Thus, electrical stress and physical stress exist in each step of image formation by the electrophotographic method. Then, the surface state of the image carrier subjected to these stresses changes with the use time.

In the past, various protective agents (sometimes referred to as a lubricant or an image carrier protective agent) for reducing friction between the image carrier and the cleaning member and improving cleaning properties, Many proposals have been made regarding supply methods.
For example, a proposal has been made to use a fatty acid metal salt as the protective agent applied to the image carrier (see Patent Document 1). However, in this proposed technique, since the fatty acid metal salt is an organic substance, the fatty acid metal salt is weak against charging hazards (particularly, charging by the AC superimposed charging method), and the fatty acid metal salt changes in quality and loses lubricity. In addition, there is a problem that deterioration of the cleaning member is accelerated and contamination of the charging member is promoted.
A proposal has been made to scrape off the protective agent of the molded body with a brush to supply the protective agent to the image carrier, to incorporate the protective agent into a developer, and to supply the protective agent to the image carrier. (See Patent Documents 2 and 3). However, this proposed technique has a problem in that depending on the materials used as the protective agent and the developer, an adverse effect on the development occurs, which hinders the formation of a high-quality image.
There has been a proposal of adding inorganic fine particles as an external additive to a toner (see Patent Document 4). However, this proposed technique adds the inorganic fine particles in order to adjust the charge amount of the toner. Even if the inorganic fine particles are used as the protective agent, the inorganic fine particles alone are sufficient. There is a problem that the effect is not obtained, the inorganic fine particles easily film on the surface of the image carrier, and it is difficult to obtain the protective effect of the image carrier.
A proposal has been made that a fatty acid metal salt and boron nitride are blended as the protective agent applied to the image carrier (see Patent Document 5). However, this proposed technique has a problem that when the boron nitride content is large, the protective agent is cured, and the supply of the protective agent to the image carrier is unstable.

  On the other hand, extending the life of the image forming apparatus and the members used in the image forming apparatus is of great interest in the market from the viewpoint of protecting the global environment by reducing running costs and waste, and the image carrier In addition, there is a demand for extending the life of the peripheral members.

  Therefore, suppression of filming, improvement in cleaning properties, and stable supply of a protective agent can be achieved, the life of the image carrier and its peripheral members can be extended, and good images can be output over a long period of time. At present, an image forming apparatus, an image forming method, and a process cartridge are not yet provided.

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, according to the present invention, filming can be suppressed, cleaning properties can be improved, and a stable supply of a protective agent can be achieved, and the life of the image carrier and its peripheral members can be extended. An object of the present invention is to provide an image forming apparatus, an image forming method, and a process cartridge capable of outputting.

Means for solving the problems are as follows. That is,
<1> An image carrier, at least a developing unit that develops an electrostatic latent image formed on the image carrier, and a protective agent supply unit that supplies a protective agent to the image carrier, The developer includes boron nitride having an average primary particle size of 2.0 μm to 14.0 μm, and the protective agent includes at least one fatty acid metal salt and an average primary particle size of 0.1 μm to 2.0 μm. An image forming apparatus including boron nitride.
<2> The developer according to <1>, wherein the developer is a two-component developer including a toner and a carrier, and boron nitride is added in an amount of 0.05% by mass to 0.5% by mass with respect to the mass of the toner. This is an image forming apparatus.
<3> The image forming apparatus according to any one of <1> to <2>, wherein the protective agent contains 5% by mass to 30% by mass of boron nitride.
<4> The image forming apparatus according to any one of <1> to <3>, wherein the fatty acid metal salt includes zinc stearate.
<5> The image forming apparatus according to any one of <1> to <4>, wherein the protective agent comprises at least a fatty acid metal salt and boron nitride mixed, heated and melted, and then cooled and solid-molded. .
<6> At least a development step for developing the electrostatic latent image formed on the image carrier and a protective agent supply step for supplying a protective agent to the image carrier, and the developer in the development step is an average primary It contains boron nitride having a particle size of 2.0 μm or more and 14.0 μm or less, and the protective agent contains at least one fatty acid metal salt and boron nitride having an average primary particle size of 0.1 μm or more and 2.0 μm or less. This is a featured image forming method.
<7> The developer according to <6>, wherein the developer is a two-component developer including a toner and a carrier, and boron nitride is added in an amount of 0.05% by mass to 0.5% by mass with respect to the mass of the toner. This is an image forming method.
<8> The image forming method according to any one of <6> to <7>, wherein the protective agent contains 5% by mass to 30% by mass of boron nitride.
<9> The image forming method according to any one of <6> to <8>, wherein the fatty acid metal salt contains zinc stearate.
<10> The image forming method according to any one of <6> to <9>, wherein the protective agent comprises at least a fatty acid metal salt and boron nitride mixed, heated and melted, and then cooled and solid-molded. .
<11> An image carrier, at least a developing unit that develops an electrostatic latent image formed on the image carrier, and a protective agent supply unit that supplies a protective agent to the image carrier, The developer includes boron nitride having an average primary particle size of 2.0 μm to 14.0 μm, and the protective agent includes at least one fatty acid metal salt and an average primary particle size of 0.1 μm to 2.0 μm. A process cartridge containing boron nitride.
<12> The developer according to <11>, wherein the developer is a two-component developer containing a toner and a carrier, and boron nitride is added in an amount of 0.05% by mass to 0.5% by mass with respect to the mass of the toner. This is a process cartridge.
<13> The process cartridge according to any one of <11> to <12>, wherein the protective agent contains 5% by mass to 30% by mass of boron nitride.
<14> The process cartridge according to any one of <11> to <13>, wherein the fatty acid metal salt includes zinc stearate.
<15> The process cartridge according to any one of <11> to <14>, wherein the protective agent comprises at least a fatty acid metal salt and boron nitride mixed, heated and melted, and then cooled and solid-molded.

  According to the present invention, the above-described problems can be solved, filming can be suppressed, cleaning performance can be improved, and a stable supply of a protective agent can be achieved, and the life of the image carrier and its peripheral members can be extended. Therefore, it is possible to provide an image forming apparatus, an image forming method, and a process cartridge capable of outputting a good image over a long period of time.

FIG. 1 is a schematic view showing an example of a protective agent supply means. FIG. 2 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a schematic view showing a process cartridge according to an embodiment of the present invention. FIG. 4 is a diagram of a solid vertical band chart used for filming evaluation in the example.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention has at least an image carrier, a protective agent supplying unit, and a developing unit, a protective layer forming unit, an electrostatic latent image forming unit, a transfer unit, a fixing unit, It has cleaning means and other means as required.
The image forming method of the present invention includes at least a protective agent supplying step and a developing step, and further includes a protective layer forming step, an electrostatic latent image forming step, a transfer step, a fixing step, and a cleaning step. Depending on the process, other steps are included.

  The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the protective agent supplying step can be performed by the protective agent supplying unit, and the developing step is performed by the developing unit. The protective layer forming step can be performed by the protective layer forming unit, the electrostatic latent image forming step can be performed by the electrostatic latent image forming unit, and the transfer step can be performed by the transfer unit. The fixing step can be performed by the fixing unit, the cleaning step can be performed by the cleaning unit, and the other steps can be performed by the other unit.

<Image carrier>
The image carrier is not particularly limited with respect to the material, shape, structure, size, etc., and can be appropriately selected from known ones. The shape is preferably a drum shape, Examples of the material include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors such as polysilane and phthalopolymethine.

<Protective agent supply means and protective agent supply step>
The protective agent supplying step is a step of supplying the protective agent to the image carrier, and can be performed by the protective agent supplying means. The protective agent supply means has at least a protective agent supply member.

<< protective agent >>
The protective agent contains at least a fatty acid metal salt and boron nitride, and further contains other components as necessary.

-Fatty acid metal salt-
The fatty acid metal salt is not particularly limited and may be appropriately selected depending on the intended purpose. For example, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, stearin Strontium acid, calcium stearate, cadmium stearate, magnesium stearate, zinc stearate, zinc oleate, magnesium oleate, iron oleate, cobalt oleate, copper oleate, lead oleate, manganese oleate, zinc palmitate, Cobalt palmitate, lead palmitate, magnesium palmitate, aluminum palmitate, calcium palmitate, lead caprylate, lead caprate, zinc linolenate, cobalt linolenate, calcium linolenate, Lumpur zinc, cadmium ricinoleate, and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, zinc stearate is preferable in terms of excellent protective layer formation speed.

As content in the said protective agent of the said fatty-acid metal salt, 70 to 95 mass% is preferable, and 80 to 90 mass% is more preferable.
When the content of the fatty acid metal salt is less than 70% by mass, the protective layer forming speed on the image carrier may be reduced and filming may occur. When the content is more than 95% by mass, the cleaning property is deteriorated. In some cases, toner slip-through increases or cleaning failure occurs.

-Boron nitride-
The boron nitride is particularly excellent in film formability because it easily cleaves and lubricates because the hexagonal mesh planes in which atoms are firmly combined overlap with each other at a wide interval, and the force acting between the layers is only weak van der Waals force. Material. Further, since boron nitride is an inorganic substance, it is chemically and thermally stable, and lubricity does not deteriorate even when charging hazard is applied.

When the protective agent contains boron nitride, the lubricity is not lost even when a charging hazard is applied, and deterioration of the cleaning performance of the image carrier can be prevented.
On the other hand, when the protective agent does not contain boron nitride, a large amount of toner may slip through the cleaning blade, and the toner may appear directly on the image or contaminate the charging member.
By supplying the protective agent containing boron nitride to the image carrier, it is possible to maintain the lubricity of the image carrier and maintain good cleaning properties even when subjected to a charging hazard.

In order to obtain the effect of improving the cleaning property for the image carrier, it is preferable that the average primary particle size of the boron nitride is small. This is because the smaller the average primary particle size, the larger the specific surface area, and the easier it is to coat the surface of the image carrier.
The average primary particle size of the boron nitride is 0.1 μm or more and 2.0 μm or less, preferably 0.3 μm or more and 0.5 μm or less.
If the average primary particle size of the boron nitride is less than 0.1 μm, it may accumulate on the image carrier and cause filming. If it exceeds 2.0 μm, the surface of the image carrier In some cases, the film cannot be sufficiently coated, and the effect of improving the cleaning property cannot be obtained.
On the other hand, when the average primary particle size of the boron nitride is within the preferable range, it is advantageous in that a cleaning property improving effect can be obtained without causing filming.
Here, the average primary particle size of the boron nitride means a number average particle size in a projected area equivalent diameter of the primary particles of the boron nitride, and for example, boron nitride is measured using an apparatus such as a scanning electron microscope. be able to.

As content in the said protective agent of the said boron nitride, 5 mass% or more and 30 mass% or less are preferable, and 10 mass% or more and 20 mass% or less are more preferable.
When the content of the boron nitride in the protective agent is less than 5% by mass, the effect of improving the lubricity and cleaning properties by the boron nitride may not be obtained. When the content exceeds 30% by mass, a large cleaning property is obtained. However, the protective agent may be cured and difficult to supply to the image carrier. Further, the boron nitride may adhere to the surface of the image carrier and cause filming.
On the other hand, when the content of the boron nitride in the protective agent is within the more preferable range, it is advantageous in that an effect of improving lubricity and cleaning properties for the image carrier can be obtained.

  There is no restriction | limiting in particular as mixing of the said boron nitride and the said fatty-acid metal salt, According to the objective, it can select suitably, For example, it is preferable to stir and mix using a well-known mixing apparatus.

The protective agent may be either a powder or a molded product, but it is formed in a block shape or a bar shape because the adjustment of the supply amount to the image carrier is easy and the device is downsized. It is preferable to do.
The method for forming the protective agent into blocks or bars is not particularly limited. For example, by heating and melting the powdery protective agent into a mold, and then cooling it. There are a method of solidifying and forming a protective agent block, a method of putting the powdery protective agent into a mold and applying pressure in the mold to form a protective agent block.

<< Protective agent supply member >>
The protective agent supply member is a member that supplies the protective agent to the surface of the image carrier.
When the protective agent block (block-shaped protective agent) is used as the protective agent, the protective agent supply member is preferably brush-shaped.
When the protective agent supply member is brush-shaped, the fibers (brush fibers) of the brush-shaped protective agent supply member (brush) are flexible in order to suppress mechanical stress with the surface of the image carrier. It is preferable to have sex.

The material for the brush fiber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyolefin resins (for example, polyethylene and polypropylene); polyvinyl resins and polyvinylidene resins (for example, polystyrene and acrylic resins). , Polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone); vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; styrene-butadiene resin; fluorine Resin (eg, polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene); polyester; nylon; acrylic; rayon; polyurethane; Boneto; phenol resins; amino resins (eg, urea - formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, polyamide resins); and the like. These may be used individually by 1 type and may use 2 or more types together.
In order to adjust the degree of bending, for example, diene rubber, styrene-butadiene rubber (SBR), ethylene propylene rubber, isoprene rubber, nitrile rubber, urethane rubber, silicone rubber, hydrin rubber, norbornene rubber and the like are combined. It may be used.

The average fiber diameter of the brush fibers is preferably 10 μm to 500 μm.
The average length of the brush fibers is preferably 1 mm to 15 mm.
The average brush density of the brush is preferably 10,000 to 300,000 per square inch (1.5 × 10 ^{7 to} 4.5 × 10 ⁸ per square meter).
Furthermore, the said protective agent supply member produced the said brush fiber from several to several hundred fine fiber from the surface of the uniformity and stability of supply, for example, The average density of the said brush fiber Is preferably high. Specifically, 50 fine fibers of 6.7 decitex (6 denier), such as 333 decitex = 6.7 decitex × 50 filament (300 denier = 6 denier × 50 filament), are bundled into one fiber. It may be the one that has been flocked.

A coating layer may be provided on the surface of the brush, if necessary, in order to stabilize the surface shape, environmental stability, etc. of the brush.
As the component forming the coating layer, it is preferable to use a component that can be deformed according to the bending of the brush fiber.
The component forming the coating layer is not particularly limited as long as it can maintain the flexibility of the brush, and can be appropriately selected according to the purpose. For example, polyethylene, polypropylene, chlorinated polyethylene , Polyolefin resins such as chlorosulfonated polyethylene; polyvinyls such as polystyrene, acrylic (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polybiliketone, and poly Vinylidene resins; vinyl chloride-vinyl acetate copolymers; silicone resins composed of organosiloxane bonds or modified products thereof (for example, alkyd resins, polyester resins, epoxy resins, polyurethanes, etc.) Modified products); fluorine resins such as perfluoroalkyl ether, polyfluorovinyl, polyfluorovinylidene and polychlorotrifluoroethylene; polyamides; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; Can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

The support for the protective agent supply member includes a fixed mold and a rotatable roll.
When the support is in the form of a roll, a roll brush produced by winding the brush fibers in a spiral shape around a metal core using a piled tape can be used as the protective agent supply member. .

<Protective layer forming means and protective layer forming step>
In the protective layer forming step, the protective agent supplied to the surface of the image carrier by the protective agent supply means is thinned using a protective layer forming member, and a protective layer is formed on the surface of the image carrier. The protective layer can be formed by the protective layer forming means.

<< Protective layer forming member >>
The protective layer forming member is not particularly limited as long as it can form a protective layer by thinning the protective agent supplied to the surface of the image carrier, and is appropriately selected according to the purpose. For example, a blade.

-Blade-
The blade is fixed to the blade support by any method such as adhesion or fusion so that the tip can be pressed against the surface of the image carrier.
There is no restriction | limiting in particular as a material of the said blade, Generally a well-known material can be suitably selected according to the objective, For example, a rubber blade, an elastic metal blade, etc. are mentioned.
There is no restriction | limiting in particular as said rubber blade, According to the objective, it can select suitably, For example, urethane rubber, hydrin rubber, silicone rubber, fluororubber etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Further, as these rubber blades, the contact portion with the image carrier may be coated with a low friction coefficient material, impregnated or the like. Further, in order to adjust the hardness of the elastic blade, a filler represented by an organic filler, an inorganic filler, or the like may be dispersed.

There is no restriction | limiting in particular as thickness of the said braid | blade, Although it cannot define uniquely by balance with pressing force, For example, 0.5 mm-5 mm are preferable and 1 mm-3 mm are more preferable.
Similarly, the length of the blade that protrudes from the blade support and can be deflected, that is, the so-called free length, is not uniquely defined by the balance with the pressing force. 15 mm is preferable and 2 mm to 10 mm is more preferable.

There is no restriction | limiting in particular as said elastic metal blade, According to the objective, it can select suitably, For example, the spring board etc. which use stainless steel, quenching ribbon steel, phosphor bronze, beryllium copper, etc. are mentioned. In addition, a surface layer such as resin, rubber, or elastomer is formed on the surface of these elastic metal blades via a coupling agent, primer component, etc., if necessary, by a method such as coating or dipping, and if necessary, heat curing is performed. If necessary, an elastic metal blade subjected to surface polishing or the like may be used.
The elastic metal blade may be subjected to processing such as bending in a direction substantially parallel to the support shaft after installation in order to suppress twisting of the blade.
There is no restriction | limiting in particular as a material which forms the said surface layer, According to the objective, it can select suitably, For example, perfluoro alkoxy alkane (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene hexafluoro Fluorine resins such as propylene copolymer (FEP) and polyvinylidene chloride (PVdF) can be used. If necessary, silicone rubber such as fluorine rubber or methylphenyl silicone elastomer may be used together with the filler.

  The thickness of the elastic metal blade is not particularly limited and is not uniquely defined by the balance with the pressing force. For example, it is preferably 0.05 mm to 3 mm, more preferably 0.1 mm to 1 mm. .

The force (pressing force) for pressing the image carrier may be such that the protective agent supplied to the surface of the image carrier is extended to be in the state of a protective layer or a protective film. For example, the linear pressure is 5 gf. / Cm to 80 gf / cm is preferable, and 10 gf / cm to 60 gf / cm is more preferable.
When the pressing force is less than 5 gf / cm, a sufficient amount of the protective agent may not be supplied, which may promote deterioration in cleaning properties and deterioration of the image carrier, and when it exceeds 80 gf / cm, The lifetime of the image carrier, the protective agent, the protective agent supply member, etc. may be reduced.

  Here, there is no restriction | limiting in particular as measurement of the said pressing force, It can select suitably from well-known things, For example, it is preferable to use only a spring.

<Developing means and development process>
The developing step is a step of developing the electrostatic latent image formed on the image carrier using a toner or a developer to form a visible image, and can be performed by a developing unit.
The developing means is not particularly limited as long as it can be developed using, for example, the toner or the developer, and can be appropriately selected from known ones. For example, the toner or developer is accommodated. Preferred examples include those having at least a developing unit capable of bringing the toner or developer into contact or non-contact with the electrostatic latent image.

<< Developer >>
As the developer, a two-component developer containing a toner and a carrier is preferable. The two-component developer is advantageous in terms of prolonging the service life when used in a high-speed printer or the like corresponding to the recent improvement in information processing speed.

-Toner-
The toner used in the present invention is added with boron nitride.
When supplying the boron nitride from the process cartridge of the present invention, which will be described later, a mechanism for supplying only boron nitride may be provided separately from the toner. However, from the viewpoint of space saving and cost reduction, such a mechanism is provided. It is preferable to supply only the toner into the developing means without providing it. However, since boron nitride added to the toner has a different function from a fluidity improver such as silica and is ultimately intended to be supplied to the surface of the image carrier, it is strongly adhered to the toner surface. Must not.

The average primary particle size of the boron nitride is 2.0 μm or more and 14.0 μm or less, and preferably 4.0 μm or more and 7.0 μm or less.
If the average primary particle size of the boron nitride is less than 2.0 μm, it may be difficult to remove with a cleaning blade, and it may accumulate on the image carrier and cause filming. When the average primary particle size of the boron nitride exceeds 14.0 μm, the effect of improving the cleaning property may be small and may appear as a white spot on the image.
On the other hand, if the average primary particle size of the boron nitride is within the preferable range, the boron nitride has the same size as the toner base particles or several times as large as the toner base particles, and therefore adheres firmly to the surface of the toner base particles. However, the effect of improving the cleaning property for the image carrier is advantageous in terms of suppressing filming.
Here, the average primary particle size of the boron nitride means a number average particle size in a projected area equivalent diameter of the primary particles of the boron nitride, and for example, boron nitride is measured using an apparatus such as a scanning electron microscope. be able to.

Since the supply amount of the developer supplied from the developing unit to the image carrier changes depending on the image area to be imaged, supply of the boron nitride in the developer is excessive depending on the image area. May be.
The amount of boron nitride added to the toner is preferably 0.05% by mass or more and 0.5% by mass or less, and more preferably 0.1% by mass or more and 0.25% by mass or less with respect to the toner mass.
When the amount of boron nitride added to the toner is less than 0.05% by mass with respect to the toner mass, the effect of improving the cleaning property may not be sufficiently exhibited, and when it exceeds 0.5% by mass, The fluidity of the developer may be lowered, and charging failure and toner scattering may be caused.
On the other hand, if the amount of boron nitride added to the toner is within the more preferable range, it is advantageous in that the effect of improving the cleaning property for the image carrier can be exhibited while maintaining the fluidity of the developer. It is.

There is no restriction | limiting in particular as mixing of the said boron nitride and the said toner, According to the objective, it can select suitably, For example, it is preferable to stir and mix using a mixing apparatus.
Examples of the mixing device include an auster mixer, a turbula mixer, a rotary blender, a container drum mixer, a V-type blender double cone blender, a ribbon blender, a paddle blender, a vertical ribbon blender, a nauter mixer, a Henschel mixer, A micro speed mixer, a flow jet mixer, etc. are mentioned.

  The toner used in the present invention is not particularly limited as long as the above conditions are satisfied, and can be appropriately selected from known ones according to the purpose. Examples of such a toner production method include a kneading / pulverization method, a polymerization method, a dissolution suspension method, and a spray granulation method.

--Kneading and grinding method--
The kneading and pulverizing method is, for example, a method of manufacturing the toner base particles by melt-kneading a toner material containing at least a binder resin and a colorant, pulverizing and classifying the obtained kneaded material. is there.
In the melt kneading, the toner materials are mixed, and the mixture is charged into a melt kneader and melt kneaded. As the melt kneader, for example, a uniaxial or biaxial continuous kneader or a batch kneader using a roll mill can be used. For example, a KTK type twin screw extruder manufactured by Kobe Steel, a TEM type extruder manufactured by Toshiba Machine Co., Ltd., a twin screw extruder manufactured by Casey Kay Co., Ltd., a PCM type twin screw extruder manufactured by Ikegai Co., Ltd. Used. This melt-kneading is preferably performed under appropriate conditions so as not to cause the molecular chains of the binder resin to be broken. Specifically, the melt-kneading temperature is determined with reference to the softening point of the binder resin. If the temperature is higher than the softening point, cutting is severe, and if the temperature is too low, dispersion may not proceed.

  In the pulverization, the kneaded product obtained by the kneading is pulverized. In this pulverization, it is preferable that the kneaded material is first coarsely pulverized and then finely pulverized. At this time, a method of pulverizing by colliding with a collision plate in a jet stream, pulverizing particles by colliding with each other in a jet stream, or pulverizing with a narrow gap between a rotor and a stator that rotate mechanically is preferably used. .

In the classification, the pulverized product obtained by the pulverization is classified and adjusted to particles having a predetermined particle diameter. The classification can be performed, for example, by removing the fine particle portion with a cyclone, a decanter, a centrifuge, or the like.
After the pulverization and classification are completed, the pulverized product is classified into an air stream by centrifugal force or the like, and toner base particles having a predetermined particle diameter can be produced.

  Next, the external additive is externally added to the toner base particles. By mixing and stirring the toner base particles and the external additive using a mixer, the surface of the toner base particles is coated while being crushed. At this time, it is important from the viewpoint of durability that the external additives such as inorganic fine particles and resin fine particles are uniformly and firmly attached to the toner base particles.

--- Polymerization method--
As a method for producing a toner by the polymerization method, for example, a toner material containing a modified polyester resin capable of at least urea or urethane bonding and a colorant is dissolved or dispersed in an organic solvent. Then, the solution or dispersion is dispersed in an aqueous medium, subjected to a polyaddition reaction, the solvent of this dispersion is removed and washed.

  Examples of the modified polyester resin capable of being bonded with urea or urethane include, for example, polyester prepolymer having an isocyanate group obtained by reacting a carboxyl group or a hydroxyl group at a terminal of a polyester with a polyvalent isocyanate compound (PIC). Can be mentioned. The modified polyester resin obtained by crosslinking and / or extending the molecular chain by the reaction of this polyester prepolymer and amines can improve the hot offset property while maintaining the low temperature fixability.

Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethyl caproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexyl). Aromatic diisocyanate (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanate (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; , Oxime, caprolactam and the like blocked. These may be used individually by 1 type and may use 2 or more types together.
The ratio of the polyvalent isocyanate compound (PIC) is preferably 5/1 to 1/1 as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group, 4/1 to 1.2 / 1 is more preferable, and 2.5 / 1 to 1.5 / 1 is still more preferable.

  As for the isocyanate group contained per molecule in the polyester prepolymer (A) which has the said isocyanate group, 1 or more are preferable, an average of 1.5-3 is more preferable, and an average of 1.8-2. Five is more preferable.

Examples of amines (B) to be reacted with the polyester prepolymer include a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4), an amino acid (B5). ), B1 to B5 amino groups blocked (B6), and the like.
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3 ′). -Dimethyl dicyclohexyl methane, diamine cyclohexane, isophorone diamine, etc.); aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like.
Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine.
Examples of the amino alcohol (B3) include ethanolamine and hydroxyethylaniline.
Examples of the amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan.
Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid.
Examples of the B1 to B5 amino group blocked (B6) include ketimine compounds and oxazolidine compounds obtained from the B1 to B5 amines and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). It is done. Among these amines (B), B1 and a mixture of B1 and a small amount of B2 are particularly preferable.

  The ratio of the amines (B) is equivalent to the equivalent ratio [NCO] / [NHx of the isocyanate group [NCO] in the polyester prepolymer (A) having an isocyanate group and the amino group [NHx] in the amine (B). ] Is preferably 1/2 to 2/1, more preferably 1.5 / 1 to 1 / 1.5, and still more preferably 1.2 / 1 to 1 / 1.2.

  According to the method for producing a toner by the polymerization method as described above, a toner having a small particle diameter and a spherical shape can be produced at low cost with little environmental load.

-Career-
There is no restriction | limiting in particular as said carrier, Although it can select suitably according to the objective, What has a core material and the resin layer which coat | covers this core material is preferable.

  There is no restriction | limiting in particular as a material of the said core material, It can select suitably from well-known things, For example, 50-90 emu / g manganese-strontium (Mn-Sr) type material, manganese-magnesium (Mn-) Mg) -based materials and the like are preferable, and highly magnetized materials such as iron powder (100 emu / g or more) and magnetite (75 to 120 emu / g) are preferable in terms of securing image density. In addition, a weakly magnetized material such as a copper-zinc (Cu—Zn) -based (30 to 80 emu / g) is advantageous in that it can weaken the contact with the photoconductor in which the toner is in a spiked state and is advantageous in improving the image quality. Is preferred. These may be used individually by 1 type and may use 2 or more types together.

The particle diameter of the core material is preferably 10 μm to 150 μm, more preferably 40 μm to 100 μm, in terms of average particle diameter (volume average particle diameter (D ₅₀ )).
When the average particle diameter (volume average particle diameter (D ₅₀ )) is less than 10 μm, the distribution of carrier particles may increase the number of fine powders, lower the magnetization per particle, and cause carrier scattering. If the thickness exceeds 150 μm, the specific surface area may decrease and toner scattering may occur. In the case of a full color having a large solid portion, the reproduction of the solid portion may be deteriorated.

  The material for the resin layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include amino resins, polyvinyl resins, polystyrene resins, halogenated olefin resins, polyester resins, and polycarbonate resins. , Polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer, vinylidene fluoride and vinyl fluoride For example, fluoroterpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, silicone resins, and the like. These may be used individually by 1 type and may use 2 or more types together.

Examples of the amino resin include urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin.
Examples of the polyvinyl resin include acrylic resin, polymethyl methacrylate resin, polyacrylonitrile resin, polyvinyl acetate resin, polyvinyl alcohol resin, and polyvinyl butyral resin.
Examples of the polystyrene resin include polystyrene resin and styrene acrylic copolymer resin.
Examples of the halogenated olefin resin include polyvinyl chloride.
Examples of the polyester resin include polyethylene terephthalate resin and polybutylene terephthalate resin.

The resin layer may contain conductive powder or the like as necessary. Examples of the conductive powder include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide.
For example, the resin layer is prepared by dissolving the silicone resin or the like in a solvent to prepare a coating solution, and then uniformly coating the coating solution on the surface of the core material by a known coating method, drying, and baking. It can be formed by doing.
Examples of the coating method include a dipping method, a spray method, and a brush coating method.
There is no restriction | limiting in particular as said solvent, According to the objective, it can select suitably, For example, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cersol butyl acetate, etc. are mentioned.
The baking is not particularly limited, and may be an external heating method or an internal heating method. For example, a stationary electric furnace, a fluid electric furnace, a rotary electric furnace, a burner furnace, etc. The method of using, the method of using a microwave, etc. are mentioned.

There is no particular limitation on the mixing of the carrier and the toner, and any one appropriately selected from known ones can be used. For example, mixing can be performed by stirring using a mixing device. Is preferred.
Examples of the mixing device include a turbula mixer, an auster mixer, a rotary blender, a container drum mixer, a V-type blender double cone blender, a ribbon blender, a paddle blender, a vertical ribbon blender, a nauter mixer, and a Henschel mixer. , Micro speed mixer, flow jet mixer and the like.

<Electrostatic latent image forming step and electrostatic latent image forming means>
The electrostatic latent image forming step is a step of forming an electrostatic latent image on the image carrier.
The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the image carrier and then performing imagewise exposure, and can be performed by the electrostatic latent image forming unit. .
The electrostatic latent image forming unit includes, for example, at least a charger that uniformly charges the surface of the image carrier and an exposure unit that exposes the surface of the image carrier imagewise.

The charging can be performed, for example, by applying a voltage to the surface of the image carrier using the charger.
The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charger including a conductive or semiconductive roll, brush, film, rubber blade, or the like. And non-contact chargers utilizing corona discharge such as corotron and scorotron.

The exposure can be performed, for example, by exposing the surface of the image carrier imagewise using the exposure device.
The exposure device is not particularly limited as long as it can be exposed like an image to be formed on the surface of the image carrier charged by the charger, and can be appropriately selected according to the purpose. Examples thereof include various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system.

<Transfer means and transfer process>
The transfer step is a step of transferring a visible image to a recording medium, and the transfer can be performed by the transfer unit.
The transfer step is a step of transferring a visible image formed on the image carrier onto a recording medium, and using an intermediate transfer member, after first transferring the visible image onto the intermediate transfer member, The visible image is preferably secondarily transferred onto the recording medium, and two or more colors, preferably full-color toner is used as the toner, and the visible image is transferred onto an intermediate transfer member to form a composite transfer image. It is more preferable to include a primary transfer step and a secondary transfer step of transferring the composite transfer image onto a recording medium.

There is no restriction | limiting in particular as said intermediate transfer body, It can select suitably from well-known things, For example, a transfer belt etc. are mentioned suitably.
The intermediate transfer member is, for example, a metal oxide such as tin oxide or indium oxide, or conductive particles such as carbon black or a conductive polymer, alone or in combination, and kneaded with a thermoplastic resin, and then extrusion molding. An endless belt obtained by centrifugal molding while adding the conductive particles and conductive polymer to the belt obtained by the above, or a resin solution containing a thermal crosslinking reactive monomer or oligomer as necessary. is there.

The transfer means includes a primary transfer means for transferring the visible image onto the intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. It is preferable to have.
The transfer unit (the primary transfer unit and the secondary transfer unit) preferably includes at least a transfer unit that peels and charges the visible image formed on the image carrier to the recording medium side. . There may be one transfer means or two or more transfer means.

Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is not particularly limited and can be appropriately selected from known recording media (such as recording paper).

<Fixing means and fixing process>
The fixing step is a step of fixing the visible image transferred on the recording medium by the fixing unit, and may be performed each time the toner of each color is transferred to the recording medium, or may be applied to the toner of each color. On the other hand, it may be performed simultaneously at the same time in a state in which they are laminated.
The fixing unit is not particularly limited and may be appropriately selected depending on the intended purpose, but a known heating and pressing unit is preferable.
Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt.

<Cleaning means and cleaning process>
The cleaning step is a step of removing the toner and the like remaining on the image carrier, and can be performed by a cleaning unit.
The cleaning means is not particularly limited as long as residual toner on the image carrier can be removed, and can be appropriately selected from known cleaners, such as a magnetic brush cleaner, an electrostatic brush cleaner, Examples thereof include a magnetic roller cleaner, a blade cleaner, a brush cleaner, and a web cleaner.

-Static elimination means and static elimination process-
The neutralization step is a step of performing neutralization by applying a neutralization bias to the image carrier, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited, and may be appropriately selected from known neutralizers as long as it can apply a neutralization bias to the electrostatic latent image carrier. Preferably mentioned.

Here, it demonstrates based on FIG. The protective agent supply apparatus 2 in FIG. 1 shows an example of the protective agent supply means.
The protective agent supply device 2 includes a protective agent 21 formed in a block shape (bar shape), a protective agent supply member 22 as a supply member, a pressing force applying mechanism 23, a protective layer forming mechanism 24, and the like. It is provided opposite to the photosensitive drum 1 as a body.
The protective layer forming mechanism 24 includes a blade 24a that contacts the photosensitive drum 1 in a non-counter direction, a blade support 24b that supports the blade 24a, and the blade 24a together with the blade support 24b. There is an urging means 24c for urging to one side.

Although the coil spring is illustrated as the pressing force applying mechanism 23 and the urging means 24c, there is no particular limitation, and for example, a member having rubber elasticity, a leaf spring, and other elastic members may be used.
The protective agent 21 comes into contact with the protective agent supply member 22 in the form of a rotating brush by the pressing force of the pressing force applying mechanism 23. The protective agent supply member 22 rotates and rubs with the photosensitive drum 1 with a linear velocity difference. At this time, the protective agent 21 held on the surface of the protective agent supply member 22 is transferred to the photoconductor. Supply to the surface of the drum 1.
The protective agent 21 supplied to the surface of the photosensitive drum 1 is thinned (formed into a film) by the protective layer forming mechanism 24.
Although it is possible to secure the supply amount of the protective agent 21 by increasing the pressing force of the pressing force applying mechanism 23, the protective agent supply member 22 is liable to deteriorate, and the protective agent is used over a long period of time. 21 cannot be stably supplied.

The deteriorated protective agent 21 is removed by the cleaning device 4 together with the toner component remaining on the photosensitive drum 1. The cleaning device 4 may be used also as the protective agent supply device 2, but the function of removing the toner component remaining on the surface of the image carrier and the function of forming a protective layer are the image carrier. In the present invention, the functions are separated, and the cleaning device 4 is provided on the upstream side of the protective agent supply device 2 in the rotation direction of the photosensitive drum 1. Yes.
The cleaning device 4 includes a cleaning blade 41 as a cleaning member, a cleaning pressing mechanism 42, and the like. Although the coil spring is illustrated as the cleaning pressing mechanism 42, there is no particular limitation, and for example, a member having rubber elasticity, a leaf spring, and other elastic members may be used.

Next, a description will be given based on FIG. A color copying machine 100 in FIG. 2 shows an example of the image forming apparatus.
The color copying machine 100 includes an apparatus main body 101, a scanner 102 provided on the upper surface of the apparatus main body 101, and an automatic document feeder (ADF) 103 provided on the scanner 102.
A paper feed unit 104 having a plurality of paper feed cassettes 104a, 104b, 104c, and 104d is provided at the lower portion of the apparatus main body 101.
An endless intermediate transfer belt 105 as an intermediate transfer member is disposed at a substantially central portion of the apparatus main body 101. The intermediate transfer belt 105 is supported by being wound around a plurality of support rollers 106, 107, 108, and the like, and is driven to rotate clockwise by a drive source (not shown).
An intermediate transfer body cleaning device 109 for removing residual toner remaining on the intermediate transfer belt 105 after secondary transfer is provided in the vicinity of the support roller 108.
On the intermediate transfer belt 105 stretched between the support roller 106 and the support roller 107, yellow (Y), magenta (M), cyan (C), black are arranged along the conveyance direction. The tandem image forming unit 10 includes process cartridges 12Y, 12M, 12C, and 12K as four image forming units (K) arranged side by side. However, these four color orders are examples, and are not limited to this.

An exposure device 8 is disposed above the tandem image forming unit 10. A secondary transfer roller 110 as a transfer device is disposed on the opposite side of the intermediate transfer belt 105 from the support roller 108. The image on the intermediate transfer belt 105 is transferred to the sheet (paper) fed from the paper feeding unit 104 by the secondary transfer roller 110.
On the left side of the secondary transfer roller 110, a fixing device 111 for fixing the transferred image on the sheet is provided. The fixing device 111 includes an endless belt-like fixing belt 111a and a pressure roller 111b that presses against the fixing belt 111a.
Below the fixing device 111, a sheet reversing device 112 for reversing the sheet when recording images on both sides of the sheet is provided substantially parallel to the tandem image forming unit 10.

Here, a series of processes for image formation will be described using a negative-positive process.
The image carrier 1 typified by a photoconductor (OPC) having an organic photoconductive layer is neutralized by a neutralizing lamp (not shown) or the like, and is uniformly negatively charged by a charging roller 3 as the charging device. .
When the photosensitive drum 1 is charged by the charging roller 3, an appropriate voltage is applied to the charging roller 3 to charge the photosensitive drum 1 to a desired potential from a voltage application device (not shown). A large voltage or a charging voltage obtained by superimposing an AC voltage thereon is applied.
The charged photosensitive drum 1 forms a latent image with laser light irradiated by the exposure device 8 such as a laser optical system (the absolute value of the exposure portion potential is lower than the absolute value of the non-exposure portion potential). ) Is performed.
The laser beam is emitted from a semiconductor laser and scans the surface of the photosensitive drum 1 in the direction of the rotation axis of the photosensitive drum 1 by a polygonal polygonal mirror (polygon) that rotates at high speed.

  The latent image formed in this way is developed with the developer composed of toner particles or a mixture of toner particles and carrier particles supplied onto the developing roller 51 of the developing device 5 to form a toner visible image. It is formed. At the time of developing the latent image, a voltage having an appropriate magnitude or a developing bias in which an AC voltage is superimposed on the voltage between the exposed portion and the non-exposed portion of the photosensitive drum 1 is supplied from a voltage application mechanism (not shown). Applied to the developing sleeve. The toner image formed on the photosensitive drum 1 corresponding to each color is transferred and transferred onto the intermediate transfer belt 105 by the transfer roller 6 and fed from the paper feeding unit 104 or a manual feed tray. A superposed toner image (color image) is collectively transferred by the secondary transfer roller 110 onto a recording medium (sheet) such as paper fed from 113. It is preferable that a potential having a polarity opposite to the toner charging polarity is applied to the transfer roller 6 as a transfer bias.

The toner particles remaining on the photosensitive drum 1 are cleaned by the cleaning blade 41 and collected in a toner collection chamber in the cleaning device 4.
The sheet after the image transfer is sent to the fixing device 111, where heat and pressure are applied to fix the transferred image, and then the sheet is stacked on the paper discharge tray 116 by the paper discharge roller pair 115.
Alternatively, the conveyance path is switched by a switching claw (not shown), put into the sheet reversing device 112, reversed there and guided again to the transfer position, and after the image is recorded on the back side, the discharge roller pair 115. As a result, the sheet is discharged onto the discharge tray 116.
After the image transfer, the intermediate transfer belt 105 has residual toner removed by an intermediate transfer member cleaning device 109, and prepares for the image formation by the tandem image forming unit 10 again.

  The image forming apparatus uses a plurality of the developing devices 5 arranged, and after sequentially transferring a plurality of toner images of different colors sequentially produced by the plurality of developing devices 5 onto an intermediate recording medium, Is not limited to the “tandem-type intermediate transfer method”, in which the toner images are transferred to a recording medium such as paper and then fixed, and a plurality of similarly produced toner images are sequentially stacked on the recording medium. For example, a “tandem direct transfer method” may be used in which fixing is performed after transfer.

  The charging roller 3 is preferably disposed in contact with or close to the surface of the photosensitive drum 1. As a result, compared to a corona discharger using a discharge wire (so-called corotron or scorotron), the amount of ozone generated during charging can be greatly suppressed. However, in the charging roller 3 that performs charging in contact with or close to the surface of the photosensitive drum 1, electric discharge is performed in a region near the surface of the photosensitive drum 1, so that electrical stress on the photosensitive drum 1 is large.

(Process cartridge)
The process cartridge of the present invention includes an image carrier, a developing unit that develops an electrostatic latent image formed on the image carrier using a developer, and a protective agent supply unit that supplies a protective agent to the image carrier. And the developer in the developing unit includes boron nitride having an average primary particle size of 2.0 μm or more and 14.0 μm or less, and the protective agent includes at least one fatty acid metal salt and an average primary. It is necessary to contain boron nitride having a particle size of 0.1 μm or more and 2.0 μm or less.

The developer is preferably a two-component developer containing a toner and a carrier, and boron nitride is preferably added in an amount of 0.05% by mass to 0.5% by mass with respect to the mass of the toner.
The protective agent preferably contains 5% by mass to 30% by mass of boron nitride.
As the fatty acid metal salt, zinc stearate is preferable.
The protective agent is preferably formed by mixing at least a fatty acid metal salt and boron nitride, heating and melting, and then cooling to form a solid.
The process cartridge of the present invention can be detachably provided for various image forming apparatuses, and is preferably provided detachably for the image forming apparatus of the present invention.

Here, it demonstrates based on FIG. A process cartridge 12 in FIG. 3 shows an example of the process cartridge.
In the process cartridge 12, a photosensitive drum 1, a protective agent supply device 2, a charging roller 3, a developing device 5, a cleaning device 4 and the like are integrally accommodated.
The developing device 5 includes a developing roller 51, conveying screws 52 and 53 for circulating the developer while stirring and conveying, a preset case 54 for containing toner, and the like.
The cleaning blade 41 is abutted at an angle similar to a so-called counter type (leading type).

The protective agent 21 is supplied from the protective agent supply member 22 to the surface of the photosensitive drum 1 from which the residual toner and the deteriorated protective agent 21 are removed by the cleaning device 4, and the protective layer forming mechanism 24 forms a film. A protective layer is formed.
The photosensitive drum 1 having a protective layer formed on the surface by the protective agent supply device 2 is charged with an electrostatic latent image by exposure light L such as a laser. The latent image is visualized as a toner image by the developing device 5 and transferred to the intermediate transfer belt 105 by a transfer roller 6 as a transfer device outside the process cartridge 12. In the case of the direct transfer method, the recording medium is preferably a sheet.

  According to the image forming apparatus, the image forming method, and the process cartridge of the present invention, the life of the image carrier and the members around the image carrier can be extended, so that a good image can be output over a long period of time.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
In the following examples and comparative examples, the average primary particle size of boron nitride is a value determined as follows.

<Average primary particle size of boron nitride>
The average primary particle size of boron nitride was determined as an average value of 20 by analyzing an observation image obtained by a scanning electron microscope (manufactured by ZEISS, ULTRA55).

Example 1
-Preparation of protective agent-
Zinc stearate (manufactured by Nippon Oil & Fats Co., Ltd., GF200) and boron nitride (manufactured by Momentive Performance Materials, average primary particle size: 0.3 μm), with a mass ratio (zinc stearate: boron nitride) of 90: 10 and mixed using an aster mixer (Cube 6640, manufactured by Oster) by stirring for 30 seconds at a stirring speed of 12,300 rpm, and then melted to form a block (300 mm × 8 mm × 10 mm). The protective agent was mounted on a protective agent supply device of a color copier (manufactured by Ricoh Co., Ltd., Imagio MP C2200).
-Production of developer-
Next, the black (Bk) toner for Imagio MP C2200 was extracted from the cartridge, boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) was added at 0.10% by mass to the toner mass, and Using a star mixer (Cube 6640, manufactured by Oster Co., Ltd.), 3 sets of stirring and stirring for 10 seconds at a stirring speed of 12,300 rpm were repeated for 3 sets.
The obtained toner and a ferrite carrier having a volume average particle diameter of 50 μm are blended in a mass ratio (ferrite carrier: toner) of 95: 5, and a stirring speed of 67 rpm is used using a turbula mixer (T2F, manufactured by Turbula). For 5 minutes. The produced developer was mounted on a developing device of a color copying machine (Imagio MP C2200, manufactured by Ricoh Co., Ltd.).

<Evaluation>
Using a color copying machine (Imagio MP C2200, manufactured by Ricoh Co., Ltd.) equipped with the produced protective agent and developer, filming on the image carrier, cleaning properties for the image carrier, monochrome (Bk), And the supply performance of the protective agent to the image carrier were evaluated as follows. The results are shown in Table 1.

<< Filming Evaluation >>
Using the chart of the solid vertical belt image shown in FIG. 4, 500 sheets were run (paper passing), and the surface of the subsequent image carrier was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
◎: Little filming occurs on the image carrier ○: Little filming occurs on the image carrier △: Filming occurs slightly on the image carrier ×: Filming is severe on the image carrier Occur (bad)

<< Evaluation of cleaning properties >>
After running 500 sheets, it is replaced with a new image carrier, and a 2 mm thick linear sponge tape (Scotch tape 4016, manufactured by Sumitomo 3M Co.) is used at the upper end of the opening of the developing means to slip through the toner catcher. (1 mm thick, 8 mm × 310 mm felt, manufactured by Ashiya Co., Ltd.) was attached. The toner catcher removes the toner slipped downstream of the cleaning blade while running 20 sheets of the 5% image area ratio chart (passing paper) after running 100 sheets using the chart having the image area ratio of 5%. Collected at. The collected slip-off toner was visually observed, and the cleaning property was evaluated according to the following criteria.
〔Evaluation criteria〕
◎: Very little toner has passed through the cleaning blade ○: Little toner has passed through the cleaning blade △: Some toner has passed through the cleaning blade ×: Very much toner has passed through the cleaning blade (bad)

<< Evaluation of protective agent supply performance >>
The protective agent supply performance was evaluated according to the following criteria based on the pressing force required to supply the protective agent to the image carrier.
The pressing force was measured with a spring alone.
〔Evaluation criteria〕
◯: It can be sufficiently supplied with the pressing force of the pressing member mounted on the Imagio MP C2200.
(Triangle | delta): The pressing force of 150%-200% of the pressing member mounted in Imagio MP C2200 is required.
X: A pressing force of 200% or more of the pressing member mounted on the Imagio MP C2200 is required (defective).

(Example 2)
In Example 1, the amount of boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) added to the black (Bk) toner in developer preparation is 0.10 mass relative to the toner mass. Evaluation was performed in the same manner as in Example 1 except that the toner content was changed from 0.25% to 0.25% by weight with respect to the toner weight. The results are shown in Table 1.

(Example 3)
In Example 1, the amount of boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) added to the black (Bk) toner in developer preparation is 0.10 mass relative to the toner mass. Evaluation was performed in the same manner as in Example 1 except that the toner content was changed from 0.5% to 0.50% by mass with respect to the toner mass. The results are shown in Table 1.

Example 4
In Example 1, in the preparation of the protective agent, a blend of zinc stearate and boron nitride (Momentive Performance Materials, average primary particle size: 0.3 μm) was mixed at a mass ratio (zinc stearate: boron nitride) of 90. : The evaluation was performed in the same manner as in Example 1 except that the mass ratio (zinc stearate: boron nitride) was changed to 80:20. The results are shown in Table 1.

(Example 5)
In Example 1, in the preparation of the protective agent, a blend of zinc stearate and boron nitride (Momentive Performance Materials, average primary particle size: 0.3 μm) was mixed at a mass ratio (zinc stearate: boron nitride) of 90. : The mass ratio (zinc stearate: boron nitride) is changed from 10 to 80:20, and boron nitride added to the black (Bk) toner in the preparation of the developer (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) ) Was added in the same manner as in Example 1 except that the amount added was changed from 0.10% by mass to 0.25% by mass with respect to the toner mass. The results are shown in Table 1.

(Example 6)
In Example 1, the composition of zinc stearate and boron nitride (manufactured by Momentive Performance Materials, average primary particle size of 0.3 μm) in the preparation of the protective agent was mass ratio (zinc stearate: boron nitride) in mass. Boron nitride added to black (Bk) toner (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5) is changed from the ratio 90:10 to the mass ratio (zinc stearate: boron nitride) to 80:20. 0.0 μm) was evaluated in the same manner as in Example 1 except that the addition amount was changed from 0.10% by mass to 0.50% by mass with respect to the toner mass. The results are shown in Table 1.

(Example 7)
In Example 2, the addition amount of boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) added to the black (Bk) toner in the developer production is 0.25 mass relative to the toner mass. Evaluation was performed in the same manner as in Example 2 except that the amount was changed from 0.0% to 0.03% by mass with respect to the toner mass. The results are shown in Table 1.

(Example 8)
In Example 2, the addition amount of boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) added to the black (Bk) toner in the developer production is 0.25 mass relative to the toner mass. Evaluation was performed in the same manner as in Example 2 except that the toner content was changed from 0.75% to 0.75% by weight with respect to the toner weight. The results are shown in Table 1.

Example 9
In Example 2, in the preparation of the protective agent, a blend of zinc stearate and boron nitride (Momentive Performance Materials, average primary particle size 0.3 μm) was mixed at a mass ratio (zinc stearate: boron nitride) of 90. : The evaluation was performed in the same manner as in Example 2 except that the mass ratio (zinc stearate: boron nitride) was changed to 97: 3. The results are shown in Table 1.

(Example 10)
In Example 2, in the preparation of the protective agent, a blend of zinc stearate and boron nitride (Momentive Performance Materials, average primary particle size 0.3 μm) was mixed at a mass ratio (zinc stearate: boron nitride) of 90. : The evaluation was performed in the same manner as in Example 2 except that the mass ratio (zinc stearate: boron nitride) was changed to 60:40. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, evaluation was performed in the same manner as in Example 1 except that boron nitride was not added to the black (Bk) toner in the preparation of the developer. The results are shown in Table 1.

(Comparative Example 2)
In Example 1, in the preparation of the protective agent, a blend of zinc stearate and boron nitride (Momentive Performance Materials, average primary particle size: 0.3 μm) was mixed at a mass ratio (zinc stearate: boron nitride) of 90. : The mass ratio (zinc stearate: boron nitride) was changed from 10 to 80:20, and evaluation was performed in the same manner as in Example 1 except that boron nitride was not added to the black (Bk) toner in the developer preparation. Went. The results are shown in Table 1.

(Comparative Example 3)
In Example 1, in the preparation of the protective agent, a blend of zinc stearate and boron nitride (Momentive Performance Materials, average primary particle size: 0.3 μm) was mixed at a mass ratio (zinc stearate: boron nitride) of 90. : The mass ratio (zinc stearate: boron nitride) was changed from 10 to 70:30, and evaluation was performed in the same manner as in Example 1 except that boron nitride was not added to the black (Bk) toner in the developer preparation. Went. The results are shown in Table 1.

(Comparative Example 4)
In Example 2, boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size of 5.0 μm) added to the black (Bk) toner in developer preparation is boron nitride (manufactured by Momentive Performance Materials, Evaluation was performed in the same manner as in Example 2 except that the average primary particle size was changed to 0.3 μm. The results are shown in Table 1.

(Comparative Example 5)
In Example 5, boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) added to the black (Bk) toner in developer preparation was boron nitride (manufactured by Momentive Performance Materials, average Evaluation was performed in the same manner as in Example 5 except that the primary particle size was changed to 0.3 μm. The results are shown in Table 1.

(Comparative Example 6)
In Example 2, boron nitride (manufactured by Momentive Performance Materials, average primary particle size 0.3 μm) in the preparation of the protective agent, boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) The evaluation was performed in the same manner as in Example 2 except that it was replaced with. The results are shown in Table 1.

(Comparative Example 7)
In Example 5, boron nitride (manufactured by Momentive Performance Materials, average primary particle size 0.3 μm) in the preparation of the protective agent was changed to boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm). The evaluation was performed in the same manner as in Example 5 except that it was replaced. The results are shown in Table 1.

(Comparative Example 8)
In Example 2, boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 5.0 μm) added to the black (Bk) toner in developer preparation was boron nitride (manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particles). Evaluation was performed in the same manner as in Example 2 except that the diameter was changed to 15.0 μm. The results are shown in Table 1.

  From the results shown in Table 1, it was found that Examples 1 to 10 can suppress filming, improve cleaning properties, and stably supply a protective agent, as compared with Comparative Examples 1 to 8. Of the above three evaluation items, up to one Δ is allowed.

  The image forming apparatus, the image forming method, and the process cartridge of the present invention can realize a long life of the image carrier and its peripheral members, and are excellent in terms of protecting the global environment by reducing running costs and waste, Since a good image can be output over a long period of time, it can be suitably used for, for example, a multifunction machine including at least one of a copying machine, a printer, a facsimile machine, and a plotter.

1 Photosensitive drum as an image carrier 1Y Photosensitive drum (for yellow)
1M Photosensitive drum (for magenta)
1C Photosensitive drum (for cyan)
1K photoconductor drum (for black)
2 Protective Agent Supply Device 3 Charging Roller as Charging Device 4 Cleaning Device 5 Developing Device 6 Transfer Roller as Transfer Device 6Y Transfer Roller (for Yellow)
6M transfer roller (for magenta)
6C transfer roller (for cyan)
6K transfer roller (for black)
8 Exposure device 10 Tandem image forming unit 12 Process cartridge 12Y Process cartridge (for yellow)
12M process cartridge (for magenta)
12C process cartridge (for cyan)
12K process cartridge (for black)
21 Protective agent (image carrier protective agent)
DESCRIPTION OF SYMBOLS 22 Protective agent supply member as supply member 23 Pressing force giving mechanism 24 Protective layer forming mechanism 24a Blade 24b Blade support 24c Energizing means 41 Cleaning blade 42 Cleaning pressing mechanism 51 Developing roller 52 Conveying screw 53 Conveying screw 54 Preset case 100 Color Copying machine 101 Main body 102 Scanner 103 Automatic document feeder 104 Paper feed unit 105 Intermediate transfer belt 106 Support roller 107 Support roller 108 Support roller 109 Intermediate transfer body cleaning device 110 Secondary transfer roller 111 Fixing device 111a Fixing belt 111b Pressure roller 112 Sheet reversing device 113 Manual feed tray 114 Transport roller pair 115 Paper discharge roller pair 116 Paper discharge tray

Japanese Patent Publication No.51-22380 JP 2004-333961 A JP 2009-48107 A JP 2007-304246 A JP 2006-350240 A

Claims (7)

  At least an image carrier, a developing unit that develops an electrostatic latent image formed on the image carrier, and a protective agent supply unit that supplies a protective agent to the image carrier. And boron nitride having an average primary particle size of 2.0 μm to 14.0 μm, and the protective agent includes at least one fatty acid metal salt and boron nitride having an average primary particle size of 0.1 μm to 2.0 μm. An image forming apparatus including the image forming apparatus.   The image forming apparatus according to claim 1, wherein the developer is a two-component developer including a toner and a carrier, and boron nitride is added in an amount of 0.05% by mass to 0.5% by mass with respect to the toner mass. .   The image forming apparatus according to claim 1, wherein the protective agent contains 5% by mass to 30% by mass of boron nitride.   The image forming apparatus according to claim 1, wherein the fatty acid metal salt contains zinc stearate.   The image forming apparatus according to claim 1, wherein the protective agent comprises at least a fatty acid metal salt and boron nitride mixed, heated and melted, and then cooled and solid-molded.   At least a developing step for developing the electrostatic latent image formed on the image carrier and a protective agent supplying step for supplying a protective agent to the image carrier, and the developer in the developing step has an average primary particle size of 2 0.0 μm or more and 14.0 μm or less of boron nitride, and the protective agent contains at least one fatty acid metal salt and boron nitride having an average primary particle size of 0.1 μm or more and 2.0 μm or less. Image forming method.   At least an image carrier, a developing unit that develops an electrostatic latent image formed on the image carrier, and a protective agent supply unit that supplies a protective agent to the image carrier. And boron nitride having an average primary particle size of 2.0 μm to 14.0 μm, and the protective agent includes at least one fatty acid metal salt and boron nitride having an average primary particle size of 0.1 μm to 2.0 μm. A process cartridge comprising: