JPH056089A - Developing device and developing roller used therefor - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to prevent strong adhesion of fine powder of one-component developer to the developer carrier, and to suppress the deterioration of the triboelectrification ability and the carrying ability of the developer for a long period of time. It is an object of the present invention to provide a developing device capable of forming a uniform developer layer and obtaining a good image without density reduction, density unevenness and ghost. A rough surface 10 having an average surface roughness Ra of 1.0 to 3.0 μm is formed on a surface of a base 6 of a developing sleeve 8 of a developing device, and graphite fine particles are dispersed on a binder resin on the rough surface 10. The resin coating layer 7 having an average surface roughness Ra of 0.8 to 2.5 μm was formed. [Effect] The rough surface 10 of the sleeve 8 having a predetermined roughness and the resin coating layer 7 can prevent the adhesion of fine powder of the one-component developer and the deterioration of the triboelectrification ability and the conveyance ability. A good image without unevenness and ghost can be obtained, and deterioration of the coating layer 7, peeling, scratches, etc. can be prevented and the life of the sleeve 8 can be extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image using a one-component developer, and more particularly to an improvement of the developer carrying member.

[0002]

2. Description of the Related Art A developing device using a one-component developer is widely used in electrophotographic copying machines and electrophotographic printers.

In such a developing device, the surface of the developer carrying member is subjected to a surface roughening treatment to improve the developer transporting performance, which is disclosed in JP-A-55-140858, 56-113172 and 57-.
It is described in Japanese Patent Publication No.-66455.

By the way, in a developing device using a one-component developer, toner particles are charged to a polarity for developing a latent image by friction with a developer carrying member. The above-described surface-roughened developer carrier also contributes to the appropriate triboelectric charging of the toner particles.

On the other hand, the developer is not consumed in the area of the developer carrier facing the non-image portion of the image carrier. However, if this condition is not consumed, the developer carrier will have an electrostatic mirroring force. It is thought that the cause is that the fine powder developer layer adheres strongly and is not easily consumed even in the image area of the image carrier, and also the charge amount of the developer on the fine powder developer layer is reduced. I will end up. Therefore, a ghost image is generated on the developed image, and the quality of the image is deteriorated.

That is, as shown in FIG. 6, since the non-printing portion (white background) is continued, only the thin developer is applied even if the printing is performed (a) portion, and the printing is continued, so the dark portion is dark. Density unevenness occurs in the portion (b) where development is performed. The mechanism of this ghost is deeply related to the layer of fine powder formed on the developer carrier. That is, there is a clear difference in the particle size distribution of the toner lowermost layer of the developer carrier between the toner consuming portion and the toner non-consuming portion, and the fine powder layer is formed in the toner lowermost layer in the non-consuming portion. is there. Since the fine powder has a large surface area per volume, it has a larger amount of triboelectric charge per mass than that having a large particle diameter, and is strongly electrostatically bound to the developer carrier by the mirroring force. . For this reason, the toner on the portion where the fine powder layer is formed cannot be sufficiently frictionally charged with the developer carrying member, so that the developing ability is deteriorated and appears as a ghost on the image.

[0007]

However, in recent years, in order to improve the image quality of the electrophotographic apparatus, the particle size of the toner has been further reduced. For example, in the case of an electrophotographic laser beam printer, when realizing a print density that is doubled from the conventional 300 dpi to 600 dpi (23.6 pel), the resolution, sharpness, etc. are increased to faithfully reproduce the electrostatic latent image. This is relatively easily solved by using a toner having a particle size of 9 μm to 4 μm.

As an example of such a small particle size toner,
The volume average particle diameter is 6.0 μm, and the volume average particle diameter is 3.5.
For example, a toner having a number distribution of 20 μm or less in a number distribution and a toner having a volume average particle size of 16 μm or more in a volume distribution of about 1% or less are used.

However, since such a small particle size toner has a larger specific surface area per volume than conventional toners, the charge amount per volume and weight increases and, as described above, the amount of fine powder is large. Due to the increase, the resin component in these small particle size toners becomes abundant, and as a result, the surface of the developer carrying member is easily contaminated by the high-triboelectrically charged fine powder of these small particle size toners. As a result, ghosts are likely to occur as described above.

As a countermeasure against the above-mentioned phenomenon, there is a technique in which a surface layer in which carbon black fine particles, graphite fine particles, etc. are dispersed in a binder resin is provided on a developer carrier to leak the electric charge of charged fine powder. , Same 1
-277265 and 2-176682.

Although the above technique is excellent in the ghost prevention effect, the surface layer is likely to be partially peeled off during long-term use, and the surface layer is abraded so that the chargeability of the toner is reduced. There are some points that the transportability is deteriorated, the toner layer becomes uneven, and the above-mentioned improvements are desired. Further, making it easy to form a surface layer having a desired average surface roughness is one of the improvements desired in the above-mentioned prior art.

An object of the present invention is to provide a developing device which can prevent strong adhesion of fine developer powder to a developer carrier and obtain a developed image with a good density.

Another object of the present invention is to use it for a long period of time.
A developer carrying member capable of forming a uniform developer layer over a long period of time by suppressing the deterioration of the triboelectrification ability and the carrying ability of the developer.
And a developing device having the same.

[0014]

According to one feature of the present invention, a developer carrying member has a rough surface formed by sandblasting and having an average surface roughness Ra of 1.0 to 3.0 μm. And a surface layer in which graphite fine particles are dispersed in a binder resin, which is applied to the rough surface of the substrate, and the average surface roughness Ra of the surface of the surface layer is 0.8 to
It is 2.5 μm.

Since the surface layer is coated on the rough surface of the substrate, the surface layer adheres strongly to the substrate and is not easily peeled off, and the change in the surface roughness of the surface layer due to use is suppressed to a small level. In addition, a surface layer having a required average surface roughness can be easily formed.

According to another feature of the present invention, another binder resin having fine particles dispersed therein is coated on the surface of the substrate on which the surface layer having fine graphite particles dispersed therein is coated. According to this, peeling of the surface layer is less likely to occur,
In addition, the change due to the use of the average surface roughness of the surface layer can be suppressed to be small.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the developing device of the present invention. In the present developing device, a one-component magnetic developer is used to develop the electrostatic latent image on the image carrier.

First, the one-component magnetic developer used in the present invention will be described.

The one-component magnetic developer is used as a binder resin for the magnetic toner as the main component, and is a homopolymer of styrene such as polystyrene and polyvinyltoluene, or a substitution product thereof; styrene-propylene copolymer, styrene-vinyltoluene copolymer. Coal, styrene-vinylnaphthalene copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene- Methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether Copolymer,
Styrene-based copolymers such as styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate , Polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin,
Tempel resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, paraffin wax, carnauba wax and the like can be used alone or in combination.

As the coloring material which can be further added to the magnetic toner, conventionally known carbon black, copper phthalocyanine, iron black and the like can be used.

As the magnetic fine particles contained in the magnetic toner, a substance which is magnetized when placed in a magnetic field is used.
Powders of ferromagnetic metals such as iron, cobalt and nickel, or alloys and compounds such as magnetite, γ-Fe ₂ O ₃ and ferrite can be used.

These magnetic particles are preferably magnetic powders having a BET specific surface area of 1 to ²⁰ m ² / g, particularly 2.5 to 12 m ² / g, and a Mohs hardness of 5 to 7 according to a nitrogen adsorption method. The content of the magnetic powder is preferably 10 to 70% by weight based on the weight of the toner.

If desired, the toner may contain a charge control agent, such as a metal complex salt of a monoazo dye, salicylic acid,
A negative charge control agent such as a metal complex salt of alkylsalicylic acid, dialkylsalicylic acid or naphthoic acid is used. Further, the toner has a volume resistivity of 10 ¹⁰ Ωcm or more, especially 10 ¹² Ωcm.
It is preferably not less than cm in terms of triboelectric charge retention and electrostatic transferability. The volume resistivity referred to here is 100
It is defined as a value obtained by molding at a pressure of kg / cm ² , applying an electric field of 100 V / cm to this, and converting the current value one minute after the application.

The amount of triboelectric charge of the negatively chargeable toner is -8 μc.
/ G to −20 μc / g is preferable. -8
When it is less than μc / g, the image density tends to be low, and the effect is particularly remarkable under high humidity. On the other hand, when it exceeds -20 μc / g, the toner charge is too high and the line image and the like become fine, and the image becomes poor especially under low humidity.

The negatively chargeable toner particles are as follows. That is, 10 g of toner particles left overnight in an environment of 25 ° C. and 50 to 60% RH and carrier iron powder not covered with a resin having a main particle size of 200 to 300 mesh (for example, manufactured by Nippon Iron Powder Co., Ltd. EFV200 / 300) 90
g and thoroughly mixed in an aluminum pot having a volume of about 200 cc under the above environment (hold in the hand and shake about 50 times up and down), and use an aluminum cell having a 400 mesh screen. Then, the triboelectric charge amount of the toner particles is measured by a usual blow-off method.
The toner particles having a negative triboelectric charge measured by this method are negatively charged toner particles.

The silica fine particles used as an external additive for improving the fluidity of the magnetic toner are so-called dry silica produced by vapor phase oxidation of a silicon halogen compound, or dry silica called fumed silica or water. So-called wet silica produced from glass or the like can be used, but dry silica which has few silanol groups on the surface and inside and has no production residue is preferable. In the case of dry silica, it is also possible to obtain a composite fine powder of silica and another metal oxide by using another metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound in the production process. Also includes.

The silica fine particles are preferably hydrophobized. A conventionally known hydrophobicizing method is used for the hydrophobicizing treatment, and the hydrophobicity is imparted by chemically treating with an organic silicon compound that reacts with or physically adsorbs the fine silica powder. As a preferred method, silica fine powder produced by vapor phase oxidation of a silicon halogen compound is treated with a silane coupling agent, or is treated with a silane coupling agent and simultaneously with an organosilicon compound.

Finally, when the hydrophobization degree of the treated silica fine powder is hydrophobized so as to show a value in the range of 30 to 80 as the hydrophobization degree measured by the methanol titration test, The developer containing the silica fine powder is preferable because the triboelectric charge amount distribution shows a sharp and uniform negative chargeability.

The methanol titration test is an experimental test for confirming the degree of hydrophobization of silica fine powder having a hydrophobized surface.

To evaluate the degree of hydrophobicity of the treated silica fines, the "methanol test" defined herein is conducted as follows. Test silica fine powder 0.2g
Is added to 50 ml of water in a 250 ml Erlenmeyer flask. Methanol is titrated from the burette until the total amount of silica is wet. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed by suspending the total amount of silica fines in the liquid and the degree of hydrophobicity is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached.

The amount of the silica fine particles applied is 0.05 to 3 parts by weight with respect to 100 parts by weight of the toner, and particularly preferably 0.1 to 2 parts by weight is excellent. It is possible to provide a developer having excellent stability and chargeability. To describe a preferable mode of addition, it is preferable that 0.01 to 1 part by weight of the silica fine powder with respect to the weight of the toner is attached to the surface of the toner particle.

Other additives, such as a tetrafluoroethylene resin, a lubricant such as zinc stearate, a fixing aid (such as low molecular weight polyethylene), or a conductive material, as long as they do not have a substantial adverse effect on the magnetic toner. A metal oxide such as tin oxide may be added as a property imparting agent.

In the production of the toner, the constituent materials are well kneaded by a heat kneader such as a hot roll, a kneader or an extruder, and then the toner is mechanically pulverized or classified to obtain the toner, or the material is put in a binder resin solution. Toner by a method of obtaining a toner by dispersing and then spraying, or by a polymerization method in which a predetermined material is mixed with a monomer that constitutes a binder resin to form an emulsion suspension and then polymerized to obtain a toner. Each method such as a method can be applied.

A developing device according to an embodiment of the present invention will be described below.

In FIG. 1, an image bearing member for bearing an electrostatic latent image formed by a known process, for example, an electrophotographic photosensitive drum 1 is rotated in the direction of arrow B. The developing sleeve 8 as a developer bearing member carries the magnetic toner 4 as a one-component magnetic developer supplied by the hopper 3 and rotates in the direction of arrow A, so that the developing sleeve 8 is rotated.
The toner 4 is conveyed to the developing area D where the photosensitive drum 1 and the photosensitive drum 1 face each other. Inside the developing sleeve 8, a magnet 5 is arranged to magnetically attract and hold the magnetic toner 4 on the developing sleeve 8. By friction with the developing sleeve 8, the toner 4 obtains a triboelectric charge capable of developing the electrostatic latent image on the photosensitive drum 1.

In order to regulate the layer thickness of the magnetic toner 4 conveyed to the developing area D, the regulating blade 2 made of a ferromagnetic metal is provided with a distance of about 200 to 300 μm from the surface of the developing sleeve 8.
It is suspended from the hopper 3 so as to face the developing sleeve 8 with a gap width of. By concentrating the magnetic force lines from the magnetic pole N _{1 of the} magnet 5 on the blade 2, a thin layer of the magnetic toner 4 is formed on the developing sleeve 8. Blade 2
It is also possible to use a non-magnetic blade.

The thin layer of the magnetic toner 4 formed on the developing sleeve 8 has a thickness of
It is preferably thinner than the minimum gap between the photosensitive drum 1 and the photosensitive drum 1. The present invention is particularly effective for a developing device of the type that develops an electrostatic latent image with such a thin toner layer, that is, a non-contact developing type developing device. However, in the developing area, the thickness of the toner layer is different from the developing sleeve 8 and the photosensitive drum 1.
The present invention can be applied to a developing device having a thickness equal to or greater than the minimum gap between the developing device and the contact developing type developing device.

In order to avoid complication of the description, a non-contact developing type developing device will be taken as an example in the following description.

A developing bias voltage is applied to the developing sleeve 8 by the power source 9 in order to fly the toner 4 from the toner layer of the magnetic toner 4 which is the one-component magnetic developer carried on the developing sleeve 8 toward the photosensitive drum 1. Is applied. When a direct current voltage is used as the developing bias voltage, a voltage having a value between the potential of the image portion (the area where the toner 4 is adhered and visualized) of the electrostatic latent image and the potential of the background portion is the developing sleeve. 8
Is preferably applied to. On the other hand, in order to increase the density of the developed image or improve the gradation, an alternating bias voltage may be applied to the developing sleeve 8 to form an oscillating electric field whose direction is alternately inverted in the developing region D. In this case, it is preferable to apply to the developing sleeve 8 an alternating bias voltage in which a DC voltage component having a value between the potential of the image portion and the potential of the background portion is superimposed.

Further, in so-called normal development in which toner is visualized by adhering toner to a high potential portion of an electrostatic latent image having a high potential portion and a low potential portion, toner charged to a polarity opposite to the polarity of the electrostatic latent image is used. On the other hand, in so-called reversal development, in which toner is visualized by adhering toner to a low potential portion of the electrostatic latent image, the toner uses a toner that is charged to the same polarity as the electrostatic latent image. The high potential and the low potential are expressed by absolute values. In any case, the toner 4 is charged to the polarity for developing the electrostatic latent image by friction with the developing sleeve 8. The silica externally added to the toner 4 is also charged by friction with the developing sleeve 8.

FIG. 2 is a block diagram showing another embodiment of the developing device of the present invention, and FIG. 3 is a block diagram showing still another embodiment of the developing device of the present invention.

In the developing device shown in FIGS. 2 and 3, as a member for controlling the layer thickness of the magnetic toner 4 on the developing sleeve 8, a material having rubber elasticity such as urethane rubber or silicone rubber, or phosphor bronze or stainless steel is used. An elastic plate 20 such as a material having metallic elasticity is used. The elastic plate 20 is pressed against the developing sleeve 8 in the developing device shown in FIG. 2 in a posture opposite to the rotational direction, and in the developing device shown in FIG. The feature is that they are pressed into contact with each other in the same direction as the rotation direction. In such a developing device, a thinner toner layer can be formed on the developing sleeve 8. 2 and 3
The other construction of the developing device is basically the same as that of the developing device shown in FIG. 1, and the same reference numerals as those in FIG. 2 and FIG. 3 denote the same members.

The developing device as shown in FIGS. 2 and 3 for forming the toner layer on the developing sleeve 8 as described above uses a one-component magnetic developer containing magnetic toner as a main component. It is also suitable for those using a one-component non-magnetic developer whose main component is non-magnetic toner. In any case, since the toner is rubbed against the developing sleeve 8 by the elastic plate 20, the triboelectric charge amount of the toner is increased and the image density is improved. Therefore, it is suitable for dealing with the shortage of the charge amount of toner in a high quality environment.

Now, the above-mentioned developing sleeve (developing roller)
Reference numeral 8 denotes a surface of the sleeve substrate 6 on which fine irregularities are provided, that is, a rough surface, on which a resin coating layer 7 containing and dispersing at least graphite fine particles is formed. Magnetic toner 4
The resin coating layer 7 is triboelectrically charged to the polarity for developing the latent image. The fine graphite particles contained are exposed on the surface of the resin coating layer 7. Since graphite leaks excess charge of the toner 4 and has excellent solid lubricity, it is useful for reducing the adhesion of the fine powder toner to the developing sleeve 8.

As the sleeve base 6, as shown in FIG. 4, the surface of a metal cylinder made of aluminum, stainless steel, brass or the like is roughened by sandblasting, or as shown in FIG. 5, aluminum, stainless steel, A fine powder of a substance different from graphite, preferably a hard inorganic substance, is applied to the metal cylinder 6'of brass or the like, and the adhesion to a resin different from the binder resin of the resin coating layer 7, preferably the metal forming the cylinder. The one formed by applying the intermediate layer 6 ″ dispersed in a resin stronger than the binder resin of the resin coating layer 7 is used.

FIG. 4 is a partially enlarged sectional view of the developing sleeve 8 using the former sleeve base 6, and FIG. 5 is a partially enlarged sectional view of the developing sleeve 8 using the latter sleeve base 6. .

Hereinafter, description will be made according to the embodiments of the present invention.

Example 1 As shown in FIG. 4, sandblasting was performed on the surface of the developing sleeve substrate 6 with irregular-shaped abrasive grains (abrasive grains having a plurality of pointed portions in which the shape of each particle is irregular). To form the rough surface 10, and to form the resin coating layer 7 on the rough surface 10,
Developing sleeve Nos. 2 to 4 according to the present invention were produced. In the developing sleeve No. 1 for comparison, the surface of the substrate 6 was not sandblasted and the rough surface 10 was not formed.

An aluminum alloy (3003) drawing pipe was used for the sleeve base 6, and sand blasting was performed with alundum abrasive grains. For the blasting, a general injection air type sandblasting machine (Pneumatic Blaster manufactured by Fuji Seisakusho) was used. The processing time was 60 seconds, and the sleeve substrate was rotated at a rotation speed of 20 rpm.

Table 1 shows the blasting conditions of the developing sleeve Nos. 1 to 4 and the average surface roughness (Ra) after the blasting.

The average surface roughness (Ra) is measured according to JIS B
The center line average roughness defined in −0601 is shown and is expressed in μm in this specification.

[0052]

[Table 1]

For forming the coating layer 7, a resin coating material containing graphite fine particles and carbon black fine particles as shown in Table 2 was used. Each part by weight shown in Table 2 was mixed, and glass beads were mixed with a paint shaker and dispersed for 3 hours to prepare a coating material. After adjusting the solid content of the coating material to 25%, the surface of the sleeve substrate 6 was prepared by an air spray method. To form a coating layer 7.

[0054]

[Table 2]

The adhering weight (coating amount) of the coating layer 7 of the developing sleeve Nos. 1 to 4 and the average surface roughness Ra of the coating layer are shown in Table 3 as surface roughness (after). The average surface roughness Ra of the sleeve base listed in Table 1 is shown again in Table 3 as the surface roughness (before).

[0056]

[Table 3]

A copying experiment was carried out by incorporating the developing sleeve Nos. 1 to 4 as described above into the developing device of the image forming apparatus.
The developing sleeve was evaluated.

The image forming apparatus used was a Canon laser beam printer LBPSX, which was used to continuously make 5000 copies under an environment in which both temperature and humidity were normal. The results are shown in Table 4.

[0059]

[Table 4]

The meaning of each mark in Table 4 is as follows. ◎:
Particularly excellent, ○: excellent, △: practically no problem, ×: practically problem, XX: unusable.

An analysis of the obtained results will be added below. The results shown in Table 4 are obtained for the continuous copying of 5000 sheets in the environment where both the temperature and humidity are low and the environment where both are high. Similarly obtained.

(A) When comparing the developing sleeves Nos. 1 to 4 with respect to the image density, only the developing sleeve No. 1 of the comparative example has a low image density. This is because in the developing sleeve Nos. 2 to 4 of the present invention, the rough surface 10 of fine irregularity having an appropriate roughness of the average surface roughness Ra of 1.0 to 3.0 is formed on the surface of the sleeve substrate 6. This is because the surface of the coating layer 7 applied and formed on the rough surface 10 becomes a rough surface having an appropriate roughness. In other words, with developing sleeve Nos. 2-4,
This is because the toner transporting force on the sleeve surface increased and the toner coating amount on the sleeve surface increased, whereas in the developing sleeve No. 1, the surface roughness was too small to exist.

Table 5 shows the Sm value of the developing sleeve surface (showing the average interval value of the irregularities on the surface of the resin layer), the surface roughness (before).
(It is the surface roughness Ra of the sleeve substrate listed in Table 1).

[0064]

[Table 5]

From the viewpoint of the average spacing Sm of the irregularities,
In order to increase the toner coating amount, as shown in Table 5, the appropriate Sm value on the surface of the developing sleeve is 30 to 70 μm.
It was found to be in the range of m.

The mean spacing of pr
ofile irregularities) Sm is specified in Section 6.4 of ISO 4287 / 1-1984.

(B) Ghost and Density Unevenness Ghosting and density unevenness are at a level above which there is no practical problem with developing sleeves Nos. 1 to 4, and developing sleeve No. 3 is particularly excellent. I understand. In these, the above-mentioned coating layer appropriately leaks the electric charge of the overcharged fine powder, and the good solid lubricity of graphite prevents the overcharged fine powder layer from being formed on the sleeve surface. Because.

(C) Film peeling While the developing sleeve No. 1 of the comparative example showed remarkable film peeling, in the developing sleeves No. 2 to 4 of the present invention, the surface of the substrate 6 was blasted to a predetermined level. It is considered that since the rough surface 10 was formed, the adhesion of the coating layer 7 to the substrate was improved, and therefore the coating did not peel off.

In the above, the case where an aluminum base is used as the developing sleeve base 6 has been shown, but the present invention is not limited to this.
As the substrate, a copper alloy, a stainless alloy, or the like could be used. As described above, the roughness of the rough surface 10 of the surface of the substrate 6 is preferably 1.0 to 3.0 in terms of the average surface roughness Ra, and it was effective in this range.

Further, it has been shown that the surface roughness of the resin coating layer 7 formed on the rough surface 10 of the substrate 6 is excellent when the average surface roughness Ra is in the range of 1.2 to 2.4 μm. But,
The present inventors have confirmed that Ra is 0.8 to
It was effective in the range of 2.5 μm.

Example 2 As shown in FIG. 5, a cylindrical base body 6 '(which corresponds to the base body of the sleeve No. 1 shown in Table 1) made of an aluminum drawing material was roughened by blasting. An intermediate resin layer 6 ″ containing fine particles of titanium oxide as a filler is applied according to the formulation shown in Table 6 to form a sleeve substrate 6 without directly forming the surface of the resin layer 6 ″. By being dispersed, the rough surface 12 having fine irregularities is formed. Incidentally, in all of Nos. 5 to 8, the coating amount of the intermediate resin layer was 4.08 g / m ² .

[0072]

[Table 6]

Then, a coating layer 7 was formed on the rough surface 12 using the resin coating material having the content shown in Table 7 to obtain developing sleeve Nos. 5 to 8 of the present invention.

[0074]

[Table 7]

Table 8 shows developing sleeve Nos. 5 to 8.
In all of Nos. 5 to 8, the coating amount of the coating layer 7 was 8.0.
It is g / m ² .

[0076]

[Table 8]

The developing sleeve Nos. 5 to 8 as described above are
As in the case of Example 1, a copying experiment was carried out by incorporating the developing sleeve in an image forming apparatus, and the developing sleeve was evaluated. The results are shown in Table 9.

[0078]

[Table 9]

In this way, in the case where the coating layer 7 is applied on the intermediate layer 6 ″, as shown in the developing sleeve No. 8, good results are obtained even when the average surface roughness Ra is 3.0 μm. This is because the rough surface shape of the coating layer 7 is different between the case of Fig. 4 and the case of Fig. 5, even if the same average surface roughness Ra is shown. It can be seen that when the surface roughness Ra is in the range of 1.0 to 3.0 μm, a sufficient toner conveying force and an appropriate toner triboelectric charging can be obtained.From the viewpoint of the average interval Sm value of unevenness, the Sm value is 40. It can be seen that a good toner conveying force can be obtained in the range of up to 70 μm.In the example of FIG. 5, the toner used for the resin layer 6 ″ containing the fine particle filler (titanium oxide in Table 6) as the base of the developing sleeve 8 is obtained. Adhesive resin (first resin)
It is desirable that the adhesiveness to the aluminum base 6'is stronger than the adhesiveness of the binder resin (second resin) of the coating layer 7 to the aluminum base 6 '. As a result, the coating layer 7 is less likely to peel off from the sleeve than when the coating layer 7 is directly applied to the substrate 6 '. Also, the coating layer 7 and the intermediate layer 6 ″ are resins that are different from each other in type, but they are easy to adapt to each other and have a strong adhesive force. Therefore, as compared with the case of FIG.
Even if the surface roughness Ra of the coated surface is small, the coating layer 7 is difficult to separate from the sleeve. In this way, since the improvement of the adhesive force to the metal substrate 6'is shared by the first resin forming the intermediate layer 6 ", the second resin forming the coating layer 7 has the hardness of the first resin. It is desirable that the hardness is higher than the hardness, in order to suppress wear of the coating layer 7.

The volume average particle size of the fine particle filler (titanium oxide in Table 6) dispersed in the intermediate layer 6 ″ in order to give the coating layer 7 an appropriate average surface roughness Ra is the same as the graphite dispersed in the coating layer 7. It is preferable that the particle size is larger than the volume average particle diameter of the fine particles. As shown in Table 6, the carbon black fine particles are dispersed in the intermediate layer 6 ″.
By adding this, the electric resistance of the intermediate layer 6 ″ is lowered as compared with the case where only the fine particle filler is dispersed, whereby the excessively charged charges of the toner flowing from the coating layer 7 can be easily flowed to the metal substrate 6 ′. In addition, the effect of the developing bias voltage can be easily exhibited.

In this way, in the case where the coating layer 7 is applied on the intermediate layer 6 ″, as shown in the developing sleeve No. 8, a good result is obtained even when the average surface roughness Ra is 3.0 μm. It is considered that this is because even if the same average surface roughness Ra is shown, the rough surface shape of the coating layer 7 is different between the case of FIG.

In any case, the average surface roughness Ra is 1.0.
It can be seen that a sufficient toner conveying force and an appropriate toner triboelectric charging can be obtained in the range of up to 3.0 μm. Also, from the viewpoint of the average spacing Sm value of the unevenness, it can be seen that a good toner conveying force can be obtained when the Sm value is in the range of 40 to 70 μm.

In the example of FIG. 5, the binder resin (first resin) used in the resin layer 6 ″ containing the fine particle filler (titanium oxide in Table 6) as the base of the developing sleeve 8 is
It is desirable that the adhesiveness to the aluminum base 6 ′ is stronger than the adhesiveness of the binder resin (second resin) of the coating layer 7 to the aluminum base 6 ′. As a result, the coating layer 7 is less likely to peel off from the sleeve than when the coating layer 7 is directly applied to the substrate 6 '. Also, the coating layer 7 and the intermediate layer 6 ″ are different in type, but they are resins so that they are easy to fit in each other and have a strong adhesive force to each other. Therefore, compared to the case of FIG. Even if the roughness Ra is small, the coating layer 7 is difficult to separate from the sleeve.

As described above, since the improvement of the adhesive force to the metal substrate 6'is shared by the first resin which constitutes the intermediate layer 6 ", the second resin which constitutes the coating layer 7 has the first hardness. 1
It is desirable that the hardness be higher than the hardness of the resin. This is to suppress wear of the coating layer 7.

The volume average particle diameter of the fine particle filler (titanium oxide in Table 6) dispersed in the intermediate layer 6 ″ in order to give the coating layer 7 an appropriate average surface roughness Ra is the same as the graphite dispersed in the coating layer 7. It is preferably larger than the volume average particle size of the fine particles.

As shown in Table 6, the carbon black fine particles are dispersed in the intermediate layer 6 "because the carbon black fine particles are dispersed in the intermediate layer 6" more than when the fine particle filler is dispersed by adding the carbon black fine particles. By lowering the electric resistance, it is possible to easily flow the excessively charged electric charge of the toner flowing from the coating layer 7 to the metal substrate 6'and to easily exert the effect of the developing bias voltage.

Since the fine particle filler such as titanium oxide mainly contributes to the roughening of the surface of the intermediate layer 6 ″, the carbon black fine particles dispersed in the intermediate layer 6 ″ have an average particle diameter larger than that of the fine particle filler. Is preferably smaller.

As the fine particle filler of the intermediate layer 6 ″, silica, potassium titanate, barium titanate, etc. can be used instead of titanium oxide. The volume average particle diameter of these fillers is 1. The thickness of 0 to 20 μm is suitable. Further, the coating amount of the intermediate layer 6 ″ on the metal cylinder 6 ′ is ² to 8 g / m ² , and good results are obtained.

In the examples of FIGS. 4 and 5, the resin coating layer 7 contains graphite fine particles and carbon black fine particles (carbon black contributes to effectively leak the overcharged portion of the toner 4). However, it was effective to include at least graphite fine particles. The volume average particle size of graphite is preferably 0.5 to 15 μm. The volume average particle size of carbon black is 5 to 300 mμ.
Was appropriate.

Since graphite also utilizes its solid lubricity, it is preferable that the average particle size is larger than that of carbon black. The ratio (weight ratio) of the resin of the coating layer 7 to graphite and carbon black, that is, resin / {(graphite) + (carbon black)} is 1/1 to 1/1
Was excellent in the range.

The amount of the resin coating layer 7 deposited is 8.0 mg / m.
^Although the case of ² was shown, a good result is obtained when the amount of adhesion is in the range of 4 to 12 mg / m ² .

As the resin binder for the coating layer 7, a phenol resin was used in each of the above examples, but in addition to this, epoxy, melamine, polyamide, silicone, polytetrafluoroethylene, polyvinyl chloride, polycarbonate, polystyrene, polymethacrylate. , Etc. could be used.

Further, in the example of FIG. 5, as the binder resin used for the intermediate layer 6 ″, other than the polyester resin shown in Table 6,
Phenolic resin, Teflon resin, epoxy resin, melamine resin, urea resin can be used. This middle layer 6 "
It is preferable to select a resin that satisfies the above-mentioned characteristics in relation to the resin of the coating layer 7. In addition, this intermediate layer 6 "
In addition, when further dispersing the carbon black fine particles in addition to the fine particle filler, the volume average particle diameter of the carbon black fine particles is appropriately 5 to 300 mμ as in the above.

The weight ratio of the resin to the fine particle filler and carbon black in the intermediate layer, that is, (resin) / {(fine particle filler) + (carbon black)} is 1/5 to
It was excellent at 3/1.

The present invention can also be applied to a developing device using a one-component non-magnetic developer. In that case, the magnet 5 is unnecessary in the example of FIGS.

Further, since the present invention has a remarkable effect of preventing ghost, it is suitable for a developing device using a one-component developer containing a toner having a particle diameter of 4-9 μm. Further, in order to develop an electrostatic latent image using developer particles frictionally charged on the surface of the developing sleeve (developing roller), the minimum gap between the developing sleeve and the image bearing member is 50 to 5 in the developing portion.
00 μm is suitable.

[0097]

As described above, in the present invention, the developer carrying member of the developing device has the average surface roughness Ra on the surface of the substrate.
Is 1.0 to 30. Since a rough surface of μm is formed and a surface layer having an average surface roughness Ra of 0.8 to 2.5 μm in which graphite fine particles are dispersed in a binder resin is formed on the rough surface, one-component development is performed. Even if a small particle size toner is used as an agent,
By developing, it is possible to obtain a good image without density reduction, density unevenness, and ghost, and deterioration, peeling of the resin coating layer,
By preventing scratches and the like, it is possible to extend the life of the developer carrier.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a developing device of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the developing device of the invention.

FIG. 3 is a configuration diagram showing still another embodiment of the developing device of the present invention.

FIG. 4 is a partially enlarged sectional view of a developing sleeve in the developing device of the present invention.

FIG. 5 is a partially enlarged cross-sectional view of another example of the developing sleeve in the developing device of the present invention.

FIG. 6 is an explanatory diagram of a ghost phenomenon.

[Explanation of symbols]

2 regulation blade 4 toner 6 Sleeve base 6'metal substrate 6 ″ middle layer 7 Resin coating layer 8 developing sleeve 10 rough surface 12 rough surface 20 elastic plate

Claims (24)

[Claims] 1. A method for transporting a one-component developer to a developing area facing an image bearing member carrying an electrostatic latent image, which is suitable for triboelectrifying the developer to a polarity for developing the latent image. And a movable developer carrier, a regulating member for regulating the layer thickness of the developer conveyed to the developing area, and a power source for applying a developing bias voltage to the developer carrier. Is a substrate having a rough surface with an average surface roughness Ra of 1.0 to 3.0 μm formed by sandblasting, and graphite fine particles dispersed in a binder resin applied to the rough surface of the substrate. And an average surface roughness Ra of the surface of the surface layer is 0.8 to 2.5 μm.
m is a developing device. 2. The developing device according to claim 1, wherein carbon black fine particles are further dispersed in the binder resin of the surface layer. 3. The adhesion amount of the surface layer to the substrate is 4 to
The developing device according to claim 2, wherein the developing device has a weight of 12 g / m ² . 4. An average spacing Sm of irregularities on the surface of the surface layer
Is 30 to 70 μm. 5. The substrate according to claim 1, wherein the surface of the metal roller is sandblasted with irregular-shaped abrasive grains.
3 or 4 developing device. 6. The developing device according to claim 1, wherein the power source applies a vibration bias voltage to the developer carrier. 7. The developing device according to claim 6, wherein the regulating member regulates a layer thickness of the developer so as to be thinner than a minimum gap between the developer carrier and the image carrier in the developing region. 8. A developing roller for triboelectrically charging a one-component developer to a polarity for developing an electrostatic latent image and supplying the same to an image carrier, and having an average surface roughness Ra formed by sandblasting of 1 A substrate roller having a rough surface of 0 to 3.0 μm, and a surface layer having graphite particles dispersed in a binder resin, which is applied to the rough surface of the substrate roller, Average surface roughness Ra is 0.8 to
A developing roller having a thickness of 2.5 μm. 9. The developing device according to claim 8, wherein carbon black fine particles are further dispersed in the binder resin of the surface layer. 10. The developing device according to claim ² , wherein the amount of the surface layer attached to the base roller is 4 to 12 g / m ² . 11. The average spacing S of the irregularities on the surface of the surface layer
The developing device according to claim 10, wherein m is 30 to 70 μm. 12. The developing device according to claim 8, wherein the base roller is formed by subjecting the surface of the metal roller to sandblasting with irregular-shaped abrasive grains. 13. Suitable for triboelectrifying the developer to a polarity for developing the latent image, for transporting the one-component developer to a developing area facing an image bearing member carrying an electrostatic latent image. And a movable developer carrier, a regulating member for regulating the layer thickness of the developer conveyed to the developing area, and a power source for applying a developing bias voltage to the developer carrier. Is a metal substrate, an intermediate layer in which fine powder is dispersed in a first binder resin applied to the metal substrate, and a surface layer in which fine graphite particles are dispersed in a second binder resin applied to the intermediate layer. And a developing device. 14. The developing device according to claim 13, wherein carbon fine powder and other fine powder having an average particle diameter larger than that of the carbon fine powder are dispersed in the first binder resin. 15. The developing device according to claim 13, wherein carbon black fine powder is further dispersed in the second binder resin. 16. The developing device according to claim 14, wherein carbon black fine powder is further dispersed in the second binder resin. 17. The developing device according to claim 13, 14, 15 or 16, wherein the adhesive force of the first binder resin to the metal of the base is larger than that of the second binder resin. 18. The developing device according to claim 17, wherein the power source applies a vibration bias voltage to the developer carrying member. 19. The regulating member controls the layer thickness of the developer,
19. The developing device according to claim 18, wherein the developing area is regulated so as to be thinner than a minimum gap between the developer bearing member and the image bearing member. 20. A developing roller for triboelectrically charging a one-component developer to a polarity for developing an electrostatic latent image and supplying it to an image carrier, a base metal roller, and a base metal roller coated on the base metal roller. An intermediate layer in which fine powder is dispersed in the first binder resin,
A developing roller having a surface layer in which fine graphite particles are dispersed in a second binder resin applied to the intermediate layer. 21. The developing roller according to claim 20, wherein carbon fine powder and other fine powder having an average particle size larger than that of the carbon fine powder are dispersed in the first binder resin. 22. The developing roller according to claim 20, wherein carbon black fine powder is further dispersed in the second binder resin. 23. The developing roller according to claim 22, wherein carbon black fine powder is further dispersed in the second binder resin. 24. The adhesion force to the metal constituting the base is
24. The developing roller according to claim 20, 21, 22, or 23, wherein the first binder resin is larger than the second binder resin.