JP2010078771A - Developer holder, manufacturing method for developer holder, developing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer holder that ensures satisfactory image density and also suppresses development ghost over a long period of time, to provide a manufacturing method for the developer holder, and a developing device that has the developer holder, and to provide an image forming apparatus that has the developing device and forms a high quality image. <P>SOLUTION: The developer holder has a surface layer made of metal on a hollow cylindrical substrate; and the surface layer has a sea-island structure that includes a sea portion made of a first metal and an island portion made of a second metal different from the first metal; and there are provided the developing device having the developer holder, the image forming apparatus having the developing device, and the manufacturing method for the developer holder. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developer holder, a method for manufacturing the developer holder, and an image forming apparatus.

  In copying machines and printing machines using electrophotographic technology, electrostatic latent images are developed by electrostatically adsorbing the developer to the electrostatic latent image formed on the photoreceptor. For this supply, a cylindrical developer holding member is used. In such development, it is necessary to supply an amount of developer corresponding to the charged potential of the photoreceptor to the electrostatic latent image.

  When a developer with a small particle size or a developer with high charging performance is used, a developing capacity distribution is generated in the developer on the developer holding member due to the development history. The developer may not be supplied. Since such development ghosts are related to the charging performance of the developer, a developer having a small particle diameter or a developer with improved charging performance, which is being developed to obtain high quality image quality, is used. This is particularly noticeable when used.

As a technique for dealing with the development ghost, for example, a method for suppressing the development ghost by providing a resin layer containing a phenol resin and carbon and having conductivity and surface lubricity on the surface of the developer holding member. Is disclosed (for example, refer to Patent Document 1).
Further, a method is disclosed in which the development ghost is suppressed by providing a film made of molybdenum, which is superior in wear resistance compared to the case where a resin layer is provided, on the surface of the developer holder (for example, a patent). Reference 2).
JP 2000-231257 A JP-A-7-281517

  An object of the present invention is to provide a developer holding body whose chargeability is controlled even when a surface layer made of metal is provided.

As a result of intensive studies, the present inventors have found that the above object can be achieved by a developer holder having a surface layer having a specific configuration, and completed the present invention.
That is, the present invention
<1> On a hollow cylindrical substrate, a surface layer made of a metal is provided, and the surface layer includes a sea part made of a first metal and an island part made of a second metal different from the first metal. A developer holding member having a sea-island structure composed of

<2> The developer holding according to <1>, wherein the first metal is one selected from Ni, Zn, and Cu, and the second metal is Pd or Sn. Is the body.

<3> The developer holder according to <1> or <2>, wherein the first metal is Cu and the second metal is Pd.

<4> The developer holder according to any one of <1> to <3>, wherein the surface layer has an area of 1.0 to 90% in the surface layer. .

<5> The developer holder according to any one of <1> to <4>, wherein an undercoat layer is provided between the substrate and the surface layer.

<6> The developer holding member according to any one of <1> to <5>, a developer supplying unit that supplies the developer onto the developer holding member, and the development supplied by the developer supplying unit. And a charging unit that charges the agent.

<7> A latent image holding member, latent image forming means for forming a latent image on the surface of the latent image holding member, and developing the latent image with toner to form a toner image. And a transfer unit that transfers the toner image to a transfer medium.

<8> The method for producing a developer holding member according to any one of <1> to <5>, wherein the surface of the hollow cylindrical substrate is subjected to electrolytic treatment with an electrolytic solution containing a first metal. After forming the sea part, including a step of forming an island part by electrolytic treatment with an electrolytic solution containing a second metal different from the first metal, and providing a surface layer having a sea island structure on the surface This is a method for producing a developer holding member.

<9> After forming the sea portion by electrolytic treatment with the electrolytic solution containing the first metal, the island portion is formed by electrolytic treatment with an electrolytic solution containing a second metal different from the first metal. Before performing the step of forming, a metal layer is formed on the surface of the hollow cylindrical substrate by electrolytic treatment with the electrolytic solution containing the first metal, and then electrolyzed with the electrolytic solution containing the second metal. The method for producing a developer holding member according to <8>, wherein the step of forming the convex portion by processing is repeated a predetermined number of times.

<10> Either <8> or <9>, wherein the first metal is one selected from Ni, Cu, and Au, and the second metal is Pd or Rd Or a developer holding member manufacturing method according to claim 1.

<11> Any one of <8> to <10>, including a step of forming a base layer on a roughened hollow cylindrical surface before the surface layer forming step. The method for producing a developer holding member as described in 1. above.

According to the first aspect of the present invention, the chargeability is controlled even when a surface layer made of metal is provided.
According to the second aspect of the present invention, a good image density is ensured as compared with the case where this configuration is not provided.
According to the invention of claim 3, a good image density is ensured as compared with the case where the present configuration is not provided.
According to the fourth aspect of the present invention, the developer holding body whose chargeability is controlled can be efficiently manufactured as compared with the case where this configuration is not provided.

<Developer holder>
The developer holder of the present embodiment includes a surface layer made of metal on a hollow cylindrical base, and the surface layer is a sea part made of a first metal and a second different from the first metal. It has a sea-island structure composed of an island part made of the above metal.
Thus, by having a sea-island structure in which different types of metals coexist in the surface layer, the wear resistance is reduced as compared with the resin layer. In addition, the surface layer exhibits an intermediate charging characteristic between the first metal and the second metal constituting the sea-island structure, and the charging property is controlled.

  When a developer with a small particle size or a developer with high charging performance is used, a developing capacity distribution is generated in the developer on the developer holding member due to the development history, and as a result, an amount corresponding to the charging potential of the photoreceptor. The developer may not be supplied. This phenomenon is called development ghost, and the generation mechanism is explained as follows.

  FIG. 5 shows an outline of a developing device using magnetic toner. The developing device includes a developer holding body 11, a magnet 12, a developer hopper 13, and a developing blade 14. Developer 15 is stored in the developer hopper 13, and the developer is attracted to the developer holder 11 by the magnetic force of the magnet 12. As the developer holding body 11 rotates, the developer attached on the developer holding body is controlled to a predetermined film thickness by the developing blade 14. Further, the developer is charged by friction between the developers and friction with the developing blade 14. The charged developer is transferred to the electrostatic latent image on the electrostatic latent image holding member by a Coulomb force at a location close to the electrostatic latent image holding member 16, and the electrostatic latent image is visualized. At the time of this visualization, only the developer located in the portion corresponding to the electrostatic latent image is consumed among the developers on the developer holder 11. A new developer is supplied to the consumed portion by the rotation of the developer holder, and is charged by the developing blade 14.

Since the development is performed in such an operation, the developer newly supplied to the portion where the developer has been consumed in the developing process is only once subjected to frictional charging by the developing blade, but the portion of the developer that has not been consumed. Repeatedly receives frictional charge.
As a result, the charge amount of the developer on the developer holder 11 has a distribution according to the development history. As the charge amount increases, the Coulomb interaction between the developer and the electrostatic latent image increases, but at the same time, the attractive force between the developer and the developer holding member also increases. The amount of developer transferred to the electrostatic latent image, that is, the developing ability, is determined by the magnitude relationship between these forces.

  In actual development, there are cases where the developing ability of the part to which the developer is newly supplied becomes higher and lower than that of the other part, and the electrostatic latent image is added to the print result accordingly. A different image appears.

  For example, consider a case where a document having a portion written as “AAAAAA” and a halftone dot region having a uniform density is copied as shown in FIG. Normally, the peripheral speed of the developer holding body 11 is faster than the peripheral speed of the electrostatic latent image holding body 16, but here the peripheral speeds of both are assumed to be equal for convenience of explanation. Further, the development is performed from above in the figure.

  Since the circumference of the developer holder is generally shorter than the length of the original, it is necessary for the developer holder to rotate a plurality of times in order to copy one original. In FIGS. 6B and 6C, the length indicated by L is the length around the developer holding member. By developing this portion, a developer layer having a distribution of developing ability in a form corresponding to the electrostatic latent image is formed on the surface of the developer holding member, and this layer allows development of the next portion. Will be done. At this time, if the developing ability of the developer in the part used for character development is higher than the developer in the other part, as shown in FIG. An image called a positive ghost, which is not in the electrostatic latent image, appears in the development result at a position corresponding to the length L. On the other hand, if the developing ability of the portion is low, the negative ghost, as shown in FIG. 6C, is developed in which the electrostatic latent image is not developed even though the electrostatic latent image exists. The phenomenon called occurs.

The method of providing a resin layer on the surface of the developer holder against negative ghost complicates the resin layer formation process, and the resin layer is easily worn. The surface state changes and the period during which development ghosts can be kept constant is short.
Further, in the method of providing a molybdenum layer on the surface of the developer holding member, when a low-temperature fixing toner developed in recent years is used, the density of the obtained image is lowered because the chargeability of molybdenum is low.

-Substrate-
The substrate according to the present embodiment has a hollow cylindrical shape. The material of the substrate is a material that can withstand the roughening of the surface as will be described later. Specifically, aluminum and its alloys, metal materials such as SUS, and the like are preferable, and aluminum or its alloy is preferable. .

In the present embodiment, in order to increase the amount of developer conveyed by the developer holding member, it is preferable to use a rough hollow cylindrical substrate.
Here, “roughening” in the present embodiment means that the arithmetic average surface roughness Ra ₁ of the substrate surface is processed to be 1.0 μm or more. Examples of the roughening of the substrate include a dry blasting method in which particles are sprayed, a honing method in which particles are sprayed in a wet method, and a grinding wheel grinding method.

In this embodiment, the surface roughness of the substrate is preferably such that the arithmetic average surface roughness Ra ₁ is in the range of 1.4 μm to 3.5 μm, and more preferably 1.7 μm to 3.2 μm. Preferably, it is 2.5 μm or more and 3.1 μm or less. If Ra ₁ is less than 1.4 μm, it will be difficult to ensure the amount of developer conveyed by the developer holder, and if it is greater than 3.5 μm, the developer holder during the roughening process. May be difficult to manufacture with high accuracy.
The arithmetic average surface roughness Ra ₁ of the substrate is measured by Tokyo Seimitsu Co., Ltd. (Surfcom 1400A-3DF) according to JIS B 0601 (2001). Specifically, 9 points in total, 3 in the circumferential direction and 3 in the axial direction, are measured under the measurement conditions of the tip of the stylus 2 μmR, the measurement speed 0.3 mm / s, the cut-off value 0.8 mm, and the measurement length 4.0 mm. It is obtained by measuring in the direction and calculating the average value. Hereinafter, the “arithmetic average surface roughness” is determined by the same measurement method.

-Surface layer-
The developer holding member of the present embodiment includes a surface layer having a sea-island structure including a sea portion made of a first metal and an island portion made of a second metal different from the first metal.
Here, the “sea-island structure” in the present embodiment means that the sea part made of the first metal and the island part made of the second metal are on the outer surface of the surface layer, that is, the surface in contact with the developer. Both mean the state of coexisting as a single metal. Further, “sea part” means that the existence ratio in the surface layer exceeds 50%.

The form of the surface layer in this embodiment will be described with reference to FIG. Here, FIG. 1 is a schematic sectional view showing an aspect of the developer holding member of the present embodiment.
As shown in FIG. 1 (a), as a first aspect of the developer holder of the present embodiment, a surface layer 40a is formed on a substrate 10, and this surface layer 40a constitutes a sea part. A form in which the convex portion 30 made of the second metal constituting the island portion is present on the metal layer 20 made of the first metal can be mentioned.

As shown in FIG. 1B, as a second aspect of the developer holding member of the present embodiment, a surface layer 40b is formed on the substrate 10, and this surface layer 40b In the thickness direction of the metal layer 20 made of the first metal, the metal lump 32 made of the second metal is dispersed and contained, and on the metal layer 20, the second metal constituting the island portion is formed. The form in which the convex part 30 which consists of exists is mentioned.
In the case of the surface layer 40b as shown in FIG. 1 (b), the metal lump 32 is included in the metal layer 20 even when the convex portion 30 which is an island portion on the surface is lost due to wear due to use. Therefore, the change in chargeability is reduced in continuous use without being biased toward the charge characteristics of the metal layer 20 alone. Further, when the metal layer 20 is further worn, the metal lump 32 in the metal layer 20 is exposed to form a new island portion, and no significant change in charging property is observed.

  In addition, in each aspect shown by FIG. 1, although the surface layer showed the aspect comprised from 2 types of metal single-piece | units, as a surface layer in this embodiment, the above-mentioned sea island structure exists on the surface If it does, the form which contains the metal different from the 1st and 2nd metal, for example, the metal layer and metal lump which consist of a 3rd metal in the range which does not impair the effect of this embodiment may be sufficient.

Nickel (Ni), zinc (Zn), copper (Cu), and gold (Au) can be applied as the first metal that forms the sea part in the sea-island structure. Cu is preferable, and Cu is particularly preferable.
In addition, palladium (Pd) and rhodium (Rd) can be applied as the second metal forming the island portion in the sea-island structure. Among these, Pd is preferable from the viewpoint of cost.

Moreover, in the surface layer in this embodiment, it is preferable that the area which an island part occupies is 1.0 to 90%. Here, the area occupied by the island means the area of the island relative to the total surface area of the surface layer, that is, the surface in contact with the developer, and the other is the area of the sea.
The area occupied by the island is more preferably in the range of 5.0 to 80%, and still more preferably in the range of 10 to 70%. Within this range, it is possible to achieve both good image density and suppression of development ghost over a long period of time.
If the area occupied by the island portion is smaller than 1.0%, the charging suppression effect by the island portion is weakened, and the developer becomes highly charged, so that a ghost is likely to be generated. Since the island portion is covered, the charge amount of the developer cannot be increased, and the density is lowered.

The area occupied by the island part exposed on the surface of the surface layer can be calculated by using a scanning electron microscope (SEM). Specifically, it is as follows.
A transparent sheet obtained by copying graph paper is superimposed on the photograph taken with the SEM in the photographing region (24 μm × 18 μm), the Pd area is measured, and the Pd area ratio in the whole is obtained.

When the surface layer in the present embodiment has a sea-island structure on the surface as shown in FIG. 1B, and the metal lump 32 is dispersed and inherent in the thickness direction of the metal layer 20, From the viewpoint of obtaining stable chargeability and wear resistance, the region (thickness) where the metal layer 20 and the metal lump 32 coexist is 1 with respect to the thickness direction from the surface of the surface layer. % Or more, preferably 5% or more.
On the other hand, it is preferable that the region where the metal lump 32 is dispersed is 90% or less from the surface of the surface layer in the thickness direction because of an increase in manufacturing steps and cost.

As for the surface roughness of the surface layer, the arithmetic average surface roughness Ra ₂ is preferably in the range of 1.0 μm to 3.2 μm, more preferably 1.7 μm to 2.9 μm. More preferably, it is 3 μm or more and 2.85 μm or less. When Ra ₂ is smaller than 1.0 μm, it is difficult to secure the amount of developer conveyed by the developer holder. When Ra ₂ is larger than 3.2 μm, the developing capability is improved because the conveying ability is improved. Although the amount of the agent increases, the developer becomes non-uniformly charged, and a developer with low charge also enters, so for example, an image failure such as toner scattering may occur at the trailing edge of the character image quality or solid image quality. This is not preferable.

Further, the arithmetic average surface roughness Ra ₂ of the surface layer is preferably such that Ra ₂ / Ra ₁ is 0.7 or more and less than 1 with respect to the arithmetic average surface roughness Ra ₁ of the substrate, and is 0.75 or more. It is more preferably 0.99 or less, and further preferably 0.80 or more and 0.98 or less. When the value of Ra ₂ / Ra ₁ is less than 0.7, the smoothness of the surface of the development holding member is increased, unevenness in developer conveyance may occur, and image density unevenness may occur. If it exceeds, ghost may occur, which is not preferable.

In order to obtain a surface layer having such a surface roughness, it is preferable to add a brightener. The addition amount of the brightener of the surface layer, can not say differs categorically on the type of metal and gloss agents, as falling within the scope of the arithmetic average surface roughness Ra _2, it is preferable to appropriately adjust.
The brightener that can be added to the surface layer is not particularly limited as long as it can be adjusted within the range of the arithmetic average surface roughness Ra _2. For example, for zinc, DuoZinc 100 and Zinclite 1600 are used. Zinclite S-3400, Zinclite K-2500, Zinclite K-7500, Zinc NH, Zinc A-100, Zinc A-200, Zinc ACK, Zinc A (above, manufactured by Okuno Pharmaceutical Co., Ltd.), etc. For tin, there can be mentioned Top Flora R, Top Flora MU (manufactured by Okuno Pharmaceutical Co., Ltd.), and the like. For nickel, Super Neolite, Super Zener, Monolite, Top Serena, Top Lunar, Top Leona NL, Acuna B-30, Acuna B, Turbo Light (above, Okuno Pharmaceutical Co., Ltd.), # 810 , # 81, # 83, # 81-J (above, manufactured by Ebara Eugelite Co., Ltd.), etc. For copper, KOTAC1, KOTAC2 (above, manufactured by Daiwa Special Co., Ltd.), Elecopper 25MU, Elecopper 25A (above, manufactured by Okuno Pharmaceutical Co., Ltd.).

The thickness of the surface layer is preferably in the range of 0.3 μm to 30 μm, more preferably 0.6 μm to 7 μm, and even more preferably 2.5 μm to 4 μm. If the thickness of the surface layer is less than 0.3 μm, the ground layer may be exposed due to repeated running, and the ghost suppression may not be maintained. If it is thicker than 30 μm, the film thickness becomes thick. In-plane roughness variation of the surface layer occurs and image density unevenness may occur, which is not preferable, and a thinner film thickness is desirable from the viewpoint of production cost. The film thickness of the surface layer here is a total of 36 film thicknesses of 4 locations in the circumferential direction and 9 locations in the axial direction per developer holder using a fluorescent X-ray film thickness meter (SFT3000S: manufactured by SII). It means the average value.
In addition, the thickness of the surface layer in this embodiment means the thickness of all the surface layers including a sea part and an island part.

-Other layers-
The developer holder of the present embodiment is not particularly limited as long as it has a substrate and a surface layer. For example, the adhesion between the substrate and the surface layer is increased, or the charge amount is adjusted. You may provide the base layer for performing.
As the underlayer, for example, a metal such as nickel, copper, chromium, or gold can be used, and nickel or copper is preferably used.
The undercoat layer may be a single layer or two or more layers. The total thickness of the undercoat layer is preferably 0.3 μm or more and 5.0 μm or less, and more preferably 1.5 μm or more and 4.0 μm or less.
The undercoat layer is preferably formed by electrolytic plating or electroless plating, and more preferably formed by electroless plating.

<Method for producing developer holder>
Hereinafter, a method for producing the developer holding member of the present embodiment will be described.
The method for producing a developer holding member of the present embodiment is different from the first metal after forming a sea part on the surface of a hollow cylindrical substrate by electrolytic treatment with an electrolytic solution containing the first metal. The method includes a step of forming an island portion by electrolytic treatment with an electrolytic solution containing a second metal, and a surface layer having a sea-island structure is provided on the surface.
By using this manufacturing method, a surface layer having a sea-island structure is formed on the surface of a hollow cylindrical substrate, and the developer holder of the above-described embodiment can be obtained.

  In the present embodiment, as shown in FIG. 1B, in addition to the surface sea-island structure, in order to obtain a surface layer in which the metal lump 32 is dispersed and contained in the metal layer 20, the first Before performing the step of forming an island portion by electrolytic treatment with an electrolytic solution containing a second metal different from the first metal after electrolytic treatment with an electrolytic solution containing one metal And forming a metal layer on the surface of the hollow cylindrical base by electrolytic treatment with the first metal-containing electrolytic solution, and then subjecting the surface to electrolytic treatment with the electrolytic solution containing the second metal. It is preferable to use a method of repeating the step of forming a predetermined number of times.

This method will be described below with reference to FIG.
First, the base 10 is immersed in an electrolytic solution containing a first metal constituting the sea portion, and an electrolytic treatment is performed using the base as a cathode to form the metal layer 20a. Then, it immerses in the electrolyte containing a 2nd metal, and forms the convex part (metal lump) 32 on the metal layer 20a [FIG. 2 (a)].
Then, this base | substrate 10 is again immersed in the electrolyte containing a 1st metal, and the metal layer 20b which consists of a 1st metal is formed on the convex part (metal lump) 32 [FIG.2 (b)]. Subsequently, the base body 10 is immersed in an electrolyte containing a second metal, and a convex portion (metal lump) is formed on the metal layer 20b.
By repeating this step a predetermined number of times (FIG. 2 (c)), a state in which the metal lump is dispersed and contained in the metal layer is obtained, and then the first method is used in the same manner as the formation of the metal layer. As shown in FIG. 1 (b), the sea part made of the metal is formed, and the island part made of the second metal is formed on the sea part by the same method as the formation of the convex part. A morphological surface layer is obtained.

Note that the number of times the formation of the metal layer and the formation of the convex portion is repeated is the number of times that the region (thickness) where the metal lump is dispersed in the thickness direction of the metal layer is obtained by the desired thickness. The desired amount may be determined as appropriate depending on the life required for the developer holder to be produced and the cost. In general, the number of repetitions is preferably 1 or more, more preferably 10 or more, and even more preferably 20 or more.
In addition, the metal layer formed between the protrusions is preferably about 0.01 to 0.3 μm in order to further reduce the change in chargeability due to wear, More preferably, it is in the range of 1 μm. This preferable range is the same in the case of the sea part between a convex part and an island part.

In the present embodiment, during the electrolytic treatment, the hollow cylindrical substrate may be immersed in an electrolytic solution containing a desired metal, and the electrolytic treatment may be performed using the substrate as a cathode.
In addition, when a brightener is added to the surface layer, the brightener is added to the electrolytic solution, and the electrolytic treatment may be performed after mixing so as to be uniform.

Note that the thickness of the metal layer or the sea part is adjusted by the temperature of the electrolytic treatment, the current density, or the electrolytic treatment time. For example, the higher the electric field treatment temperature, the higher the current density, and the longer the electric field treatment time, the larger the film thickness.
Further, when forming the convex portion (metal lump) or the island portion, the size (area occupied by the island portion) is adjusted by the temperature of the electrolytic treatment, the current density, or the electrolytic treatment time. For example, the higher the electric field treatment temperature, the higher the current density, and the longer the electric field treatment time, the larger the electric field treatment.
By changing the electrolytic treatment conditions as described above, the final film thickness of the surface layer is controlled.

  The surface roughness of the surface layer is controlled by adjusting the surface roughness of the substrate, the shape and size of the islands, the amount of brightener added to the surface layer, and the thickness of the surface layer.

  In addition, you may produce a surface layer not only by the said electroplating but by electroless plating.

<Developing device>
The developing device according to the present embodiment includes a developer holding member, a developer supplying unit that supplies the developer onto the developer holding member, and a charging unit that charges the developer supplied by the developer supplying unit. Have.

  Here, the developer holder in the developing device of this embodiment is the developer holder of this embodiment.

  The developer supply means in the developing device of the present embodiment is not particularly limited as long as it is used for supplying the developer to the developer holder, such as a stirring member (agitator), a spiral conveyance member (auger), and the like. What is normally applied to a developing device is appropriately applied.

  The charging means in the developing device of the present embodiment is not particularly limited as long as it can charge the developer to a charge amount that can be transferred to the electrostatic latent image on the electrostatic latent image holding member by Coulomb force. The charging means can be used without any limitation, and charging means normally used in a developing device is appropriately applied. Usually, the developer is charged by friction between the developers or friction with a developer layer regulating member for controlling the developer attached on the developer holding member to a predetermined film thickness.

The developer applicable to this embodiment may be either a magnetic one-component developer or a two-component developer.
As the composition of the developer that can be applied to the developing device of the present embodiment, the composition that is usually applied to the developer is appropriately applied.

FIG. 3 shows an example of a developing device suitable for carrying out this embodiment, but the present invention is not limited to this.
In FIG. 3, the developing device 3 is disposed opposite to the image carrier 1. In the developing housing 8, a developing roll section 4 and a stirring member (developer supply means) 9 are provided. A magnetic roll 5 for forming a uniform magnetic field in the axial direction, a developer holder (developing sleeve) 6 mounted on the outer periphery of the magnet roll 5, and the developing sleeve 6 are pressed against the developing roll unit 4. And a developer layer regulating member 7 made of a soft elastic body.
The magnet roll 5 has a magnetic pattern indicated by N and S, for example, in the drawing, and is fixed to the developing housing 8 in the developing sleeve 6. The developing sleeve 6 is rotatably supported by the developing housing 8. An agitating member 9 for agitating the developer T is also rotatably provided in the developing housing 8.

  As a configuration of the developer layer regulating member 7 used in the present embodiment, a member in which a soft elastic sheet is formed on a plate material such as stainless steel, copper, iron and resin is used. Examples of the soft elastic sheet include silicone rubber, urethane rubber, butadiene rubber, natural rubber, isoprene rubber, styrene butadiene rubber, butyl rubber, nitrile butadiene rubber, chloroprene rubber, ethylene propylene rubber, epichlorohydrin rubber, and the like. A material obtained by molding an elastic body alone, or a material obtained by directly attaching a sheet to a metal sheet metal such as iron, stainless steel, or aluminum is also used.

  The developer T is agitated and conveyed by the rotation of the agitating member 9 in the hopper 2, so that the developer T that can withstand high-quality images can be supplied to the developing roll unit 4 side. After the developer T adheres to the surface of the developing sleeve 6 by the magnetic force of the magnet roll 5, the layer thickness is regulated by the protruding amount of the developer layer regulating member 7 and the contact pressure, and the developer T is triboelectrically charged. The developer that is frictionally charged and conveyed onto the developing sleeve 6 moves to the image carrier 1 according to the amount of charge and is developed.

  In such a developing method, the surface of the developer holding member is subjected to strong stress such that the developer is pressed due to friction between the developing sleeve 6 and the developer layer regulating member 7 in contact therewith. Since the developer holding member in the form is less worn and the amount of developer transported to the image holding member 1 is stabilized, the occurrence of development ghosts can be suppressed over a long period of time, and a good image density can be obtained. .

<Image forming apparatus>
The image forming apparatus according to this embodiment includes a latent image holding member, latent image forming means for forming a latent image on the surface of the latent image holding member, and developing the latent image with toner to form a toner image. The developing device according to the present exemplary embodiment and a transfer unit that transfers the toner image to a transfer target.

  FIG. 4 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of the image forming apparatus of the present embodiment. An image forming apparatus 100 shown in FIG. 4 includes an electrophotographic photosensitive member (image holding member) 107, a charging device 108 such as a corotron or a scorotron for charging the electrophotographic photosensitive member 107, and a power source 109 connected to the charging device 108. An exposure device (latent image forming means) 110 that exposes the electrophotographic photosensitive member 107 charged by the charging device 108 to form an electrostatic latent image, and develops the electrostatic latent image formed by the exposure device 110 with toner. Then, a developing device (developing unit) 111 that forms a toner image, a transfer device (transfer unit) 112 that transfers the toner image formed by the developing device 111 to the transfer member 500, and the electrophotographic photosensitive member 107 after transfer. A cleaning device 113 that removes the toner being discharged, a static eliminator 114, and a fixing device (fixing means) 115.

As each device in the image forming apparatus 100, any of those employed in a conventional image forming apparatus can be applied.
In the present embodiment, an image forming apparatus in which the static eliminator 114 is not provided may be used. In FIG. 4, the charging device 108 is a contact-type charging device, but may be a non-contact type charging device such as a corotron charger.
Furthermore, other configurations that are normally applied to the image forming apparatus may be provided as appropriate.

  Hereinafter, the present embodiment will be described more specifically by way of examples. However, the present embodiment is not limited to these examples.

[Example 1]
(Preparation of developer holder 1)
-Fabrication of substrate-
After the pultrusion molding, the hollow cylindrical Al (aluminum: A6063) pipe subjected to the cutting process was subjected to a blasting treatment using FGB # 60 / # 80 which is a spherical abrasive. The blast pressure was 0.2 MPa, and the blast time was 60 seconds.
The arithmetic average surface roughness Ra ₁ of the obtained aluminum tube (substrate) was measured by the above method and found to be 3.2 μm.

-Formation of underlayer-
The aluminum tube (base) subjected to the blast treatment is subjected to Ni-P electroless treatment using a main agent (manufactured by Okuno Seiyaku Kogyo; trade name Top Nicolo BL-M / BL-1), and is formed of nickel. An underlayer having a thickness of 3.0 ± 0.5 μm was formed.

-Formation of surface layer-
Using a liquid obtained by adding a brightener to a copper sulfate bath built using a main agent (trade name; copper sulfate, manufactured by Sumitomo Metal Mining Co., Ltd.), the aluminum tube (substrate) on which the base layer is formed is used as a cathode. The metal layer (sea part) which consists of copper was formed. Here, the treatment time was 5 minutes, the treatment temperature was 20-25 ° C., and the voltage was 2V.
Thereafter, using a Pd bath that was constructed using a main agent (trade name: IPC Axela, manufactured by Okuno Pharmaceutical Co., Ltd.), an electrolytic treatment was performed using the aluminum tube (substrate) on which the metal layer was formed as a cathode, and from palladium. The convex part (island part) which becomes is formed. Here, the treatment time was 60 seconds, the treatment temperature was 25 ° C., and the Ph was 2.2 to 2.3.

After the electrolytic treatment, the substrate was washed with water a plurality of times, and then dried in an atmosphere of 50 ° C. for 10 minutes or more to obtain a developer holder 1 having a structure as shown in FIG.
The arithmetic average surface roughness Ra ₂ of the obtained surface layer was measured by the above method and found to be 2.6 μm.

(Observation of the sea-island structure and measurement of the area occupied by the island)
The surface layer of the obtained developer holder 1 was observed with SEMEDX Type N (manufactured by HITACHI) to confirm the presence or absence of a sea-island structure.
As a result, a sea-island structure of a sea part made of copper and an island part made of palladium was confirmed.
Moreover, it was 9.3% when the area which the island part occupied in the surface layer measured by the said method.

(Evaluation)
-Evaluation of development ghost-
Magnetic one-component development prepared by the following method using a modified machine in which the developer holder of the image forming apparatus (Fuji Xerox Co., Ltd., DocuPrint 340A) is changed to the developer holder 1-1 to 1-8 produced above. After printing one solid black and three solid whites with the agent, 50 ghost chart images shown in FIG. 6 were printed continuously, and the print results were visually inspected, and evaluated according to the following criteria. .
A: No ghost occurred
○: Generation of ghost is slight Δ: Ghost is generated but is in a practically acceptable level ×: Ghost is clearly generated and is not acceptable

(Preparation of developer)
Binder resin: Polyester resin 50 parts by mass (alcohol component: propylene oxide adduct of bisphenol A, acid component: terephthalic acid, MI: 5 g / 10 min, Tg: 60 ° C.)
Magnetite (particle size: 0.25 μm) 50 parts by mass Polypropylene wax 3.5 parts by mass (trade name: 660P, manufactured by Sanyo Chemical Co., Ltd.)

The material having the above composition was powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder having a set temperature of 140 ° C. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a volume average particle diameter D50 of 5.8 μm. Further, this pulverized product was classified to obtain a toner classified product having D50 of 6.2 μm and particles of 4 μm or less of 22% by number.
The average of surface treatment with 1.2 parts by mass of dimethylsilicone oil-treated silica fine particles having a particle size of 12 nm (carbon amount 7.5% by mass) and 10% by mass of decyltrimethoxysilane with respect to 100 parts by mass of the obtained toner classified product. A magnetic one-component developer was prepared by externally adding 0.6 parts by mass of titanium oxide fine particles having primary particles of 50 nm using a Henschel mixer.

Further, development for evaluation of development ghost was performed using a non-contact jumping development method under the following conditions.
Development bias (AC): Square wave, 1.8 kVpp, Duty ratio 50%, Frequency 3.3 kHz
Development bias (DC): -410V
・ V _HIGH : -500V, V _LOW : -150V
・ Distance between drum and developer holder: 220 μm
-Ambient temperature: 28 ° C, humidity: 85% RH

-Evaluation of image density-
The image density was evaluated by the following method.
The image density was evaluated by measuring the print result with an X-Rite densitometer (manufactured by X-Rite) and evaluating the density according to the following criteria based on the amount of variation in the density.
A: Fluctuation amount is less than 5% B: Fluctuation amount is 5% or more and less than 10% X: Fluctuation amount is 10% or more The evaluation results are shown in Table 1.

[Comparative Example 1]
(Preparation of developer holder a)
A substrate prepared by cutting aluminum tube material (A6063) is DIP-coated with a coating solution in which graphite and carbon are dispersed at a ratio of 40/20 parts to 100 parts of phenol resin, and fired at 170 ° C. Thus, a developer holding member a was produced.
The developer holding body a thus obtained was evaluated for development ghost and image density in the same manner as in Example 1. The results are also shown in Table 1.

[Comparative Example 2]
(Preparation of developer holder b)
A base body having a roughened surface is produced by subjecting the holding body aluminum pipe material (A6063) to cutting and blasting, and a main agent (trade name: copper sulfate manufactured by Sumitomo Metal Mining) is applied to the surface, followed by washing and drying. Thus, a developer holding member b was produced.
With respect to the obtained developer holder b, development ghost and image density were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[Comparative Example 3]
(Preparation of developer holder c)
In Example 1, it was dried for 10 minutes in an atmosphere of 30 ° C. using a molybdenum bath built using a main agent (trade name; 5C011, manufactured by Nippon Surface Chemical Co., Ltd.), then naturally dried and composed of molybdenum. A developer holding member c was produced in the same manner except that the surface layer was formed.
The developer holding member c thus obtained was evaluated for development ghost and image density in the same manner as in Example 1. The results are also shown in Table 1.

As is clear from Table 1, by using a developer holder having a surface layer having a sea-island structure on a hollow cylindrical substrate, it is possible to achieve both suppression of ghost generation and securing of image density. I understand.
On the other hand, a ghost was seen in the sleeve of Comparative Example 1, and a ghost was seen in the sleeve of Comparative Example 2 having a surface layer of only copper. Further, the sleeve of Comparative Example 3 having a surface layer of only molybdenum has a problem in image density although no ghost is observed.

[Examples 2 to 6]
(Preparation of developer holders 2 to 6)
After forming the metal layer and the convex portion in the same manner as in the method for producing the developer holding body 1 of Example 1, the step of further forming the metal layer (sea portion) and the convex portion (island portion) by the following method. And developer holders 2 to 6 were obtained.
Using a copper sulfate bath built using a main agent (trade name: copper sulfate, manufactured by Sumitomo Metal Mining), electrolytic treatment was performed using the aluminum tube (substrate) on which the above base layer was formed as a cathode, and a metal layer ( Sea part) was formed. Here, the treatment time was the time (seconds) shown in Table 2 below, the treatment temperature was 20 to 25 ° C., and the voltage was 2V.
Thereafter, electrolytic treatment was carried out using a Pd bath built using a main agent (trade name: IPC Axela, manufactured by Okuno Seiyaku Kogyo Co., Ltd.), with the aluminum tube (substrate) on which the metal layer was formed as a cathode, and a convex portion. (Island) was formed. Here, the treatment time was 60 seconds, the treatment temperature was 25 ° C., and the Ph was 2.2 to 2.3.
The arithmetic average surface roughness Ra _{2 of} the obtained surface layer and the area occupied by the islands in the surface layer were measured by the above methods, and the results are also shown in Table 2.

For the obtained developer holders 2 to 6, development ghost and image density were evaluated in the same manner as in Example 1.
The development ghost was evaluated by continuing printing up to 500 sheets by the method described above.
The evaluation results are shown in Table 2.

As shown in Table 2, when a developer holding body having a surface layer having a sea-island structure on a hollow cylindrical substrate is used, generation of ghosts is suppressed even during long-term use, and image density is also good. I understand. In particular, as in Examples 2 to 6, when the processing time for forming the second metal layer was 5 to 50 seconds, it was found that ghosting can be suppressed even when more printing is performed.
This is because the metal layer between the island part and the metal block separating the island part does not become too thick because the processing time at the time of the second metal layer formation is appropriate, and the surface layer is worn by continuing printing. Thus, even if the island part is removed, it is considered that the occurrence of ghosts cannot be seen up to 500 sheets by showing an intermediate charging characteristic between copper and palladium.

[Examples 7 to 10]
(Preparation of developer holders 7 to 10)
After forming the metal layer and the convex portion in the same manner as in the method for producing the developer holding body 1 of Example 1, the step of further forming the metal layer (sea portion) and the convex portion (island portion) by the following method. And developer holders 7 to 10 were obtained.
Using a copper sulfate bath built using a main agent (trade name: copper sulfate, manufactured by Sumitomo Metal Mining), electrolytic treatment was performed using the aluminum tube (substrate) on which the above base layer was formed as a cathode, and a metal layer ( Sea part) was formed. Here, the treatment time was 10 seconds, the treatment temperature was 20 to 25 ° C., and the voltage was 2V.
Thereafter, electrolytic treatment was carried out using a Pd bath built using a main agent (trade name: IPC Axela, manufactured by Okuno Seiyaku Kogyo Co., Ltd.), with the aluminum tube (substrate) on which the metal layer was formed as a cathode, and a convex portion. (Island) was formed. Here, the treatment time was the time (seconds) shown in Table 3 below, the treatment temperature was 25 ° C., and Ph was 2.2 to 2.3.
The arithmetic average surface roughness Ra _{2 of} the obtained surface layer and the area occupied by the islands in the surface layer were measured by the above methods, and the results are also shown in Table 3.

With respect to the obtained developer holders 7 to 10, the development ghost and the image density were evaluated in the same manner as in Example 1.
The development ghost was evaluated by continuing printing up to 500 sheets by the method described above.
The evaluation results are shown in Table 3.
Here, in order to compare the area of the island portion, the evaluation results of Example 3 are also shown in Table 3.

As shown in Table 3, when a developer holding body having a surface layer having a sea-island structure on a hollow cylindrical substrate is used, generation of ghosts is suppressed even during long-term use, and image density is also good. I understand. In particular, it can be seen that this effect is more excellent when the area occupied by the islands falls within the range of 4.8 to 54%.
On the other hand, as in Comparative Example 4, when the developer holding body having a surface layer whose entire surface is covered with palladium because the processing time at the time of forming the convex portion is too long, the generation of ghosts cannot be suppressed, Also, a good image density could not be obtained.

[Examples 11 to 25]
(Preparation of developer holders 11 to 25)
After forming the metal layer and the convex portion in the same manner as in the method for producing the developer holding body 1 of Example 1, the step of further forming the metal layer (sea portion) and the convex portion (island portion) by the following method. These were repeated the number of times shown in Table 4 below to obtain developer holders 11 to 25.
Using a copper sulfate bath built using a main agent (trade name: copper sulfate, manufactured by Sumitomo Metal Mining), electrolytic treatment was performed using the aluminum tube (substrate) on which the above base layer was formed as a cathode, and a metal layer ( Sea part) was formed. Here, the treatment time was the time (seconds) shown in Table 4 below, the treatment temperature was 20 to 25 ° C., and the voltage was 2V.
Thereafter, electrolytic treatment was carried out using a Pd bath built using a main agent (trade name: IPC Axela, manufactured by Okuno Seiyaku Kogyo Co., Ltd.), with the aluminum tube (substrate) on which the metal layer was formed as a cathode, and a convex portion. (Island) was formed. Here, the treatment time was the time (seconds) shown in Table 4 below, the treatment temperature was 25 ° C., and Ph was 2.2 to 2.3.
The arithmetic average surface roughness Ra _{2 of} the obtained surface layer and the area occupied by the islands in the surface layer were measured by the above method, and the results are also shown in Table 4.

For the obtained developer holders 11 to 25, development ghost and image density were evaluated in the same manner as in Example 1.
The development ghost was evaluated by continuing printing up to 50000 sheets by the method described above.
The evaluation results are shown in Table 4.
Here, in order to compare the number of repetitions of the processing, the evaluation results of Example 2, Example 3, and Example 5 are also shown in Table 4.

  As shown in Table 4, when a developer holding body having a surface layer having a sea-island structure on a hollow cylindrical substrate is used, generation of ghosts is suppressed even in long-term use, and image density is also good. I understand. In particular, it has been found that the greater the number of processing repetitions, the more ghosts can be suppressed even when more printing is performed.

(A)-(b) It is a schematic sectional drawing which shows the aspect of the developer holding body of this embodiment. (A)-(c) It is a schematic sectional drawing for demonstrating the manufacturing method of the developer holding body of this embodiment. It is a schematic block diagram which shows an example of the image development apparatus of this embodiment. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a figure which shows the general structure of a developing device. (A)-(C) It is a figure for demonstrating the ghost which generate | occur | produces when printing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,107 Image holding body 2 Hopper 3, 111 Developing apparatus 4 Developing sleeve part 5 Magnet roll 6 Developing sleeve (Developer holding body)
7 Developer layer regulating member 8 Developing housing 9 Stirring member 10 Base 20 Metal layer (sea)
30 Convex (island)
32 Metal lump (island)
40 Surface layer 100 Image forming apparatus 108 Charging apparatus 109 Power supply 110 Exposure apparatus 112 Transfer apparatus 113 Cleaning apparatus 114 Static eliminator 115 Fixing apparatus 500 Transfer body T Magnetic single component developer

Claims (4)

Provided with a surface layer made of metal on a hollow cylindrical substrate,
The developer holding member, wherein the surface layer has a sea-island structure composed of a sea part made of a first metal and an island part made of a second metal different from the first metal. A developer holder according to claim 1;
Developer supply means for supplying the developer onto the developer holder;
Charging means for charging the developer supplied by the developer supply means;
A developing device comprising: A latent image carrier,
Latent image forming means for forming a latent image on the surface of the latent image holding member;
The developing device according to claim 2, wherein the latent image is developed with toner to form a toner image;
Transfer means for transferring the toner image to a transfer object;
An image forming apparatus comprising: A method for producing a developer holder according to claim 1,
The surface of the hollow cylindrical substrate is electrolyzed with an electrolyte containing a first metal to form a sea portion, and then electrolyzed with an electrolyte containing a second metal different from the first metal. And a step of forming an island portion, and a surface layer having a sea-island structure is provided on the surface.

Images