JPH09269651A - Developing roller and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing roller capable of securing stable toner electrifying property even in the case of using over a long term, and surely reproducing an excellent image over a long period, by improving the conductivity stability and contamination resistance, while preventing other property such as the adhesive strength owing to hardness lowering from being deteriorated, by reforming of the roller surface. SOLUTION: The developing roller 1 composed by forming an elastic layer 3 provided with conductivity on an outer periphery of a conductive shaft 2 and further forming a surface skin layer 4 on the elastic layer 3 as necessary, visualizes an electrostatic latent image, by carrying the developer and forming a thin layer of the developer on the surface, coming, in a state of the above, into contact with or close to he latent image carrier carrying the electrostatic latent image on the surface and feeding the developer onto the latent image carrier surface, and metallic oxide particles of <=30μm average grain size are stuck-fixed on the roller 1 surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus such as a copying machine or a printer, or an electrostatic recording apparatus, in which a developer is supplied to the surface of a latent image holding member having an electrostatic latent image held on the surface of the electrostatic latent image holding member. The developing roller for visualizing the latent electrostatic image and the developing device using the developing roller will be described in more detail. The conductive stability and the stain resistance are excellent, and a good image can be reliably obtained even in long-term use. The present invention relates to a developing roller and a developing device using the developing roller.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, an electrostatic recording apparatus, etc., a developer (toner) is supplied to the surface of a latent image holding member such as a photosensitive drum holding an electrostatic latent image. A contact developing method is known as a developing method for visualizing an electrostatic latent image on the surface of a latent image carrier (US Pat. No. 315).
No. 2021, No. 3731146, etc.), this method has advantages that a magnetic material is not required, so that the apparatus can be simplified and miniaturized easily, and toner can be easily colored.

In this contact developing method, a developing roller carrying a toner (usually a non-magnetic one-component developer) on its surface is brought into direct contact with or close to the surface of a latent image holding member such as a photosensitive drum to form a toner. Is developed by adhering to the surface of the latent image carrier, and therefore the developing roller must be formed of an elastic body.

That is, in this contact developing method, as shown in FIG. 2, for example, the developing roller is provided between the toner applying roller 5 for supplying toner and the photosensitive drum 6 holding the electrostatic latent image. 1 is in contact with the photosensitive drum 6 and is spaced apart from the toner applying roller 5 by a small amount. The developing roller 1, the photosensitive drum 6 and the toner applying roller 5 are provided.
Toner is supplied to the surface of the developing roller 1 by the toner applying roller 5, and the toner is adjusted into a uniform thin layer by the stratifying blade 8 in this state. 1 is the photosensitive drum 6
The toner formed in a thin layer by electrostatically adhering to the latent image on the photosensitive drum 6 from the developing roller 1 by rotating while making contact with the latent image is visualized. In the figure, reference numeral 9 is a transfer portion, which transfers a toner image onto a recording medium such as paper, and 10 is a cleaning portion, which is cleaned by a cleaning blade 11 and is transferred to the surface of the photosensitive drum 6 after transfer. The residual toner is removed.

In this case, the developing roller 1 must rotate while securely holding the state in which the developing roller 1 is in close contact with the photosensitive drum 6. Therefore, as shown in FIG. The shaft 2 has a structure in which an elastic layer 3 is formed on the outer periphery of an elastic body made of an elastic material such as urethane rubber, silicone rubber, NBR, EPDM, etc., or a polyurethane foam, etc., to which a conductive agent is added to provide conductivity. . Further, it has been proposed to provide a conductive layer made of a resin mixed with a conductive powder or a very thin insulating layer as the skin layer 4 on the elastic layers 3.

[Problems to be Solved by the Invention]

However, the performance of these conventional developing rollers is not always satisfactory from the viewpoint of maintaining stable developing performance for a long period of time, and further improvement in performance is desired. In this case, there is still room for improvement in performance deterioration during long-term use due to the charging property and stain resistance of the toner, but the improvement of the elastic layer 3 and the skin layer 4 reduces the hardness. There is a limit to the improvement because of the balance with other characteristics such as the improvement of adhesion by
It is desired to improve these properties by modifying the roller surface where the toner and the developing roller come into contact with each other.

The present invention has been made in view of the above circumstances, and the modification of the roller surface does not deteriorate other characteristics such as an improvement in adhesion due to a reduction in hardness, and the conductive stability,
(EN) Provided are a developing roller capable of improving stain resistance, ensuring stable toner chargeability even in long-term use, and reliably reproducing a good image for a long term, and a developing device using the developing roller. The purpose is to

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has formed an elastic layer having conductivity on the outer periphery of a good conductive shaft, and has a developer on the surface. To form a thin layer of the developer, and in this state, the developer is supplied to the surface of the latent image holding member by contacting or approaching the latent image holding member holding the electrostatic latent image on the surface. hand,
In the developing roller for visualizing the electrostatic latent image, by adhering and fixing fine metal oxide particles having an average particle diameter of 30 μm or less on the roller surface, other characteristics such as adhesion improvement due to low hardness are deteriorated. In addition, it is possible to improve conductivity stability and stain resistance and achieve stable toner chargeability even in long-term use. Particularly, by using titanium oxide as metal oxide particles, the purpose can be effectively achieved. The present invention has been discovered and the present invention has been completed.

Therefore, according to the present invention, an elastic layer having conductivity is formed on the outer periphery of a shaft having good conductivity, and a developer is carried on the surface to form a thin layer of the developer. In a developing roller for visualizing the electrostatic latent image by supplying a developer to the surface of the latent image holding member by contacting the latent image holding member holding the electrostatic latent image on the surface thereof, an average particle diameter is formed on the roller surface. Provided is a developing roller having metal oxide particles of 30 μm or less adhered and fixed.

According to the present invention, the latent image holding member for holding an electrostatic latent image on the surface thereof is brought into contact with the surface of the latent image holding member while the outer peripheral surface of the latent image holding member is loaded with the developer, so that the latent image is formed by the developer. There is provided a developing device comprising a developing roller that supplies the electrostatic latent image to the surface of a holding body to visualize the electrostatic latent image, wherein the developing roller of the present invention is used as the developing roller.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The developing roller of the present invention, as shown in FIG.
A roller 1 in which an elastic layer 3 having conductivity is formed on the outer circumference of a shaft 2 having good conductivity, and a skin layer 4 is further formed if necessary.
It is obtained by adhering and fixing fine metal oxide particles on the surface of.

Here, as the shaft 2, any one can be used as long as it has good conductivity, but normally, a cored bar made of a solid body, a cylindrical body hollowed out, etc. The metal or resin shaft of is used.

Elastic layer 3 formed on the outer periphery of the shaft 2
Is formed of an elastic material having conductivity, and uses, for example, an elastomer or foam material such as polyurethane or EPDM as a base material, and conductive powder such as carbon black, metal, metal oxide, or sodium perchlorate. A material to which conductivity is imparted can be suitably used by mixing an ion conductive material such as.

In this case, the conductivity of the elastic layer 3 is not particularly limited, but the resistance value is 10 ³ to 10 ¹⁰ Ω.
It is preferable to adjust to a medium resistance region of cm ² , particularly 10 ⁴ to 10 ⁸ Ωcm ² . Resistance value is 10 ³ Ωc
If it is less than m ² , electric charge may leak to a latent image holding member such as a photosensitive drum, or the developing roller itself may be destroyed by a voltage. On the other hand, if it exceeds 10 ¹⁰ Ωcm ² , the background fog on the image may occur. It tends to occur.

Specific examples of the base material of the elastic layer 3 include polyurethane, natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber and acrylic. Examples thereof include rubber and mixtures thereof, and particularly polyurethane and EPDM.
Is preferred.

The polyurethane used as the base material of the elastic layer 3 will be described. As a polyhydroxyl compound for obtaining the polyurethane, a polyol used for producing a general flexible polyurethane foam or a urethane elastomer, for example, a polyhydroxyl group at a terminal is used. In addition to polyether polyols having, polyester polyols, and polyether polyester polyols that are copolymers of both, polyolefin polyols such as polybutadiene polyol and polyisoprene polyol, and an ethylenically unsaturated monomer are polymerized in the polyol. A general polyol such as a so-called polymer polyol obtained by the above can be used. Further, as the isocyanate compound, similarly, a polyisocyanate used in the production of general flexible polyurethane foams and urethane elastomers, that is, tolylene diisocyanate (TDI), composition TDI, 4,4′-diphenylmethane diisocyanate (MDI), composition MDI, carbon number 2
18 aliphatic polyisocyanates, alicyclic polyisocyanates having 4 to 15 carbon atoms, and mixtures and modified products of these polyisocyanates such as prepolymers obtained by partially reacting with polyols are used.

In this case, the mixing ratio of the polyol and the polyisocyanate is usually about polyisocyanate / polyol = 1 to 1.3, but the mixing ratio is less than 1 particularly for the purpose of lowering the hardness of the elastic layer 3. Good.

E used as a base material for the elastic layer 3
Explaining PDM, this EPDM is a terpolymer composed of ethylene, propylene and a third component, and the third component is not particularly limited,
Dicyclopentadiene, ethylidene norbornene, 1,
4-hexadiene and the like are preferably used. The proportions of ethylene, propylene and the third component are not particularly limited, but the content of ethylene is 5 to 95% by weight, the content of propylene is 5 to 95% by weight, and the content of the third component is The iodine value is preferably 0 to 50. Note that two or more types of EPDM having different iodine values can be used in combination. In this case, silicone rubber, silicone-modified EPDM, or both of them may be blended and used. The mixing amount of the silicone rubber, the silicone-modified EPDM, or a blend thereof may be 5 to 80 parts by weight with respect to 100 parts by weight of EPDM. The silicone-modified EPDM refers to a hybrid rubber in which the binding force between both polymers of EPDM and silicone is enhanced through a silanol compound or siloxane.

The elastic layer 3 having EPDM as a base material,
A cross-linking agent and a vulcanizing agent can be added in order to cross-link this into a substance on rubber. In this case, a crosslinking aid, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanization retarder, etc. can be used in both cases of organic peroxide crosslinking and sulfur crosslinking. Further, in addition to the above, it is necessary to add peptizers, foaming agents, plasticizers, softening agents, anti-tacking agents, separating agents, release agents, extenders, coloring agents, etc., which are generally used as a compounding agent for rubber. You can

As the conductive material blended in the elastic layer 3, conductive powder or particles of carbon, metal, metal oxide, conductive polymer or the like, or ion conductive material is preferably used.

More specifically, as the conductive powder or particles, conductive carbon such as Ketjen black EC or acetylene black, SAF, ISAF, HAF, FE can be used.
Rubber carbon such as F, GPF, SRF, FT, MT, etc.
Metals and metal oxides such as color (ink) carbon that has been subjected to oxidation treatment, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium, etc.
Examples thereof include conductive polymers such as polyanine, polypyrrole, and polyacetylene. Among these, the carbon-based conductive material is advantageous in that the resistance is less dependent on the environment, is relatively inexpensive, and the conductivity can be controlled in a small amount. In addition,
These electrically conductive powders and particles are not particularly limited, but are usually used in an amount of 0.5 to 50 parts by weight, particularly 1 to 30 parts by weight with respect to 100 parts by weight of urethane or EPDM.

Specific examples of the ionic conductive substance include inorganic ionic conductive substances such as sodium perchlorate, calcium perchlorate and lithium chloride, modified aliphatic dimethyl ammonium sulfate, stearyl ammonium acetate, lauryl ammonium acetate. , Octadecyltrimethylammonium perchlorate, tetrabutylammonium borofluorate, and other organic ionic conductive materials. These ionic conductive materials are advantageous in that the resistance is uniform and the voltage dependence is small. In addition, although these ion conductive materials are not particularly limited, usually urethane or EPDM100 is used.
0.01 to 30 parts by weight, especially 0.01 to 30 parts by weight
Used in the range of 5 parts by weight.

Further, the elastic layer 3 is made of various charge control agents such as nigrosine, triaminophenylmethane, cationic dye, silicone resin, silicone rubber, nylon, etc. for the purpose of controlling the charge amount of the carried toner. Fine powder can be added. in this case,
The amount of these additives added is the above-mentioned polyurethane or EPDM.
It is preferable that the charge control agent is 1 to 5 parts by weight and the fine powder is 1 to 10 parts by weight with respect to 100 parts by weight.

The hardness of the elastic layer 3 is not particularly limited, but is preferably 60 ° or less, particularly 25 to 55 ° on the JIS-A scale. In this case, if the elastic layer 3 has a JIS-A hardness of more than 60 °, the contact area with the photosensitive drum or the like may be reduced, and good development may not be achieved. When the developing roller is deformed or eccentric for some reason, uneven density of the image occurs. Therefore, even when the hardness of the elastic layer 3 is set to be low,
It is preferable to make the compression set as small as possible, and specifically, it is preferable that the compression set be 20% or less.

The developing roller of the present invention, as shown in FIG. 1, is a resin containing conductive powder on the elastic layer 3 for the purpose of lowering the frictional resistance of the roller surface and improving the toner charge amount to some extent. A conductive layer made of, or a very thin insulating layer can be formed as the skin layer 4. This skin layer 4
Any resin component may be used as long as it is capable of forming a film on the elastic layer 3 which has excellent strength and does not deform or fall off even after long-term use.
Phenolic resin, nylon, fluororesin, alkyd resin, melamine resin, silicone resin, acrylic resin, acrylic urethane resin, and these modified resins alone,
Alternatively, two or more kinds can be mixed and used. As the conductive material used in the case where these resins are made conductive to form a conductive layer, the same conductive materials as those exemplified as the conductive material used in the elastic layer 3 can be exemplified. It is preferable to use carbon for the layer 4. In this case, the carbon used as the conductive material of the skin layer 4 is not particularly limited, but the one having an oil supply amount of 80 ml / 100 g or less and the specific surface area of 160 m ² / g or less, particularly the oil supply amount of 30 to 80 ml, the specific surface area 30-1
It is preferable to use one having 50 m ² / g. Examples of such carbon include Printex35 and Print.
ex25 (manufactured by Degussa), CF9, # 52, #
45 (manufactured by Mitsubishi Kasei Co., Ltd.) can be exemplified. The carbon content may be 5 to 60 parts by weight, especially 10 to 40 parts by weight, based on 100 parts by weight of the resin component.

The thickness of the skin layer 4 is appropriately selected according to the type of base resin and whether it is a conductive layer or an insulating layer.
Although not particularly limited, when the skin layer 4 is used as a conductive layer, it is preferably 1 to 100 μm, particularly preferably 3 to 50 μm, and when it is less than 1 μm, the roller base material itself is exposed on the surface. There is a possibility that the characteristics of the epidermis layer cannot be fully drawn out, while 100 μm
If it exceeds, the roller surface becomes hard depending on the type of the base resin, and the elasticity of the elastic layer 3 cannot be sufficiently exerted.
The skin layer 4 may not be able to follow the elastic deformation of the elastic layer 3 and cracks may occur. Further, when the skin layer 4 is used as an insulating layer, it is preferably a very thin layer having a thickness of 50 μm or less, particularly 1 to 30 μm. When it exceeds 50 μm, the roller surface is completely covered with the insulating layer, and the entire roller is In some cases, a good image cannot be obtained because the resistance is extremely increased.

As a method for forming the skin layer 4 on the elastic layer 3, a coating solution is prepared by dissolving the resin component in a solvent and dispersing or dissolving an additive material such as a conductive material, which is optionally added thereto. The method of applying to the surface of the elastic layer 3 is preferably adopted. The concentration of the resin component in this coating solution is not particularly limited, but is appropriately selected according to the thickness of the skin layer 4 to be formed, but it is usually preferably about 2 to 20%. As the solvent for preparing this coating solution, any solvent can be used as long as it can dissolve the resin forming the skin layer, lower alcohols such as methanol, ethanol and isopropanol, ketones such as methyl ethyl ketone and cyclohexane, Toluene and xylene are preferably used. In particular, it is preferable to use a mixed solvent of these in order to obtain a favorable film property in the drying step after coating. A dispersant may be added to the coating solution for the purpose of improving the dispersion stability of the conductive material such as carbon.

The coating solution can be applied by a spray method, a roll coater method, a dipping method or the like after preparing the solution. For example, the application by dipping is performed by immersing the roller composed of the shaft 2 and the elastic layer 3 in the coating solution having the resin concentration at room temperature for 5 seconds to 5 minutes, preferably 10 seconds to 1 minute, and pulling it up to dry. Can be adopted. When the spray method is adopted, the resin concentration in the coating solution can be set higher than that in the dipping method, and for example, a coating solution prepared to have a concentration of 30 to 60% can be used. In any case, the coating may be performed by appropriately selecting the optimum resin concentration, coating method, and coating conditions so as to obtain a desired film thickness.

The developing roller of the present invention adheres and fixes the metal oxide particles on the elastic layer 3 or, when the skin layer 4 is formed, by fixing the metal oxide particles on the elastic layer 3 to improve the toner charge amount and toner resistance. It has improved pollution resistance. In this case, examples of the metal oxide include titanium oxide, zinc oxide, lead oxide, aluminum oxide, tin oxide, molybdenum oxide, vanadium pentoxide, and the like. In this case, titanium oxide, vanadium pentoxide, molybdenum oxide and the like are preferably used when the developing roller is used to perform development by positively charging the developer, and among these, titanium oxide is particularly preferably used. Further, in the case of a developing roller that develops by negatively charging the developer, zinc oxide, lead oxide, aluminum oxide, tin oxide or the like is preferably used. The average particle size of these metal oxide particles is 3
The average particle size is 0 μm or less, preferably 0.1 to 10 μm, and when the average particle size exceeds 30 μm, the distribution of the particles themselves may appear in the image.

As a method for adhering and fixing the metal oxide particles to the roller surface, a method of rubbing the roller surface with a non-woven fabric containing metal oxide particles is preferably used to adhere and fix the metal oxide particles to the roller surface. However, in the case of more uniformly attaching and fixing, the metal oxide is dispersed in an appropriate solvent, and the roller is immersed in the dispersion,
It is possible to employ a method in which the dispersion liquid is contained in a non-woven fabric and applied to the surface of the roller so as to be stretched, and then the solvent is scattered by heating. In this case, the metal oxide particles adhere to and are fixed on the roller surface by their own adsorption force, and exert an adsorption force that can sufficiently endure the image display.

Here, one of the reasons why the chargeability of the toner is improved and stabilized by adhering and fixing the metal oxide particles on the roller surface is electronegativity as a property of the metal oxide. For example, those having a high electronegativity such as titanium oxide and vanadium pentoxide have the property of being easily negatively charged by themselves, and thus exhibit the effect of positively charging the toner, such as zinc oxide and lead oxide. On the contrary, if the electronegativity is low, the toner itself is likely to be positively charged, and thus the toner is likely to be negatively charged. Another is the high dielectric constant of metal oxides. In particular, titanium oxide has a relative dielectric constant of 100 or more at a measurement frequency of 1 MHz, and it is considered that this is because the charged charge of the toner is easily expressed. Further, it is considered that the reason why the stain resistance is improved is that the metal oxide has excellent stain resistance as compared with various resin materials, and the roller surface is covered with this metal oxide, so that the stain resistance is improved.

The developing roller of the present invention can be used by incorporating it in an ordinary developing device for developing by a contact developing method. Specifically, as shown in FIG. The developing roller 1 of the present invention is provided between the roller 5 and the latent image holding member 6 such as a photosensitive drum holding an electrostatic latent image.
Is provided in contact with the latent image carrier 6 and the toner 7 is supplied to the developing roller 1 by the toner applying roller 5.
This is adjusted to a uniform thin layer by the layering blade 8, and toner is further supplied from this thin layer to the latent image holding member 6 to adhere the toner to the electrostatic latent image of the latent image holding member 6 to visualize the latent image. To do. Note that the details of FIG. 2 have already been described in the related art, and thus description thereof will be omitted.

In this case, the developing roller and the developing device of the present invention are preferably used both when the developer is positively charged for development and when the developer is negatively charged for development. The metal oxide to be attached and fixed to the surface is appropriately selected and used according to the charge polarity of the agent.

[0034]

The developing roller of the present invention is improved in conductivity stability and stain resistance without deteriorating other characteristics such as adhesion improvement due to low hardness by modifying the roller surface. In addition, it is possible to secure a stable toner charging property even in long-term use and reliably reproduce a good image for a long period of time. Therefore, the developing device using the developing roller of the present invention can surely perform good and stable development for a long period of time.

[0035]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. [Example 1] 100 parts by weight of polyether polyol having a molecular weight of 5,000 by adding propylene oxide and ethylene oxide to glycerin and urethane-modified MD
I25.0 parts (weight part, the same hereafter), 1,4-butanediol 2.5 parts, dibutyltin laurate 0.01 part,
Denka black (manufactured by Denki Kagaku Kogyo Co., Ltd.) (2.0 parts) was blended, poured into a mold heated to 110 ° C., and cured for 2 hours to form a conductive elastic layer made of polyurethane on the outer circumference of a metal shaft. A layer was formed to produce a conductive member. The surface of the obtained conductive member is dry-polished to form a roller, and the surface roughness is JIS 10 point roughness Rz =
The thickness was adjusted to 15 μm (JIS-A hardness = 52 °).

On the other hand, titanium oxide (average particle size 5 μm) was dispersed in a 50% by weight ethanol solution, the dispersion was put in a cylindrical glass container, and the roller-shaped conductive member was placed therein at 1 cm / sec. After the titanium oxide is attached to the surface of the conductive member by immersing it at the same speed and pulling it at the same speed, it is dried in an atmosphere at 80 ° C for 1 hour to remove ethanol, and the resulting roller surface is evenly rubbed with a nonwoven fabric. Then
Titanium oxide particles having weak adhesion were removed, and the titanium oxide particles adhering were mechanically fixed to obtain a developing roller.

The developing roller thus obtained was incorporated into the developing apparatus shown in FIG. 1 as the developing roller 1, and this developing apparatus was incorporated into the developing unit of a commercially available laser beam printer, and an image was formed by using a polyester positive charging toner. ,
Image evaluation was performed. The obtained image was a good image without any image defects such as fog and uneven density.

Further, when the charge amount of the toner carried on the surface of the developing roller was measured using a Faraday gauge,
It had a sufficient charge amount of 15 μC / g. Furthermore, a continuous sheet passing test of 10,000 sheets was conducted using the above laser beam printer using the developing roller of the present example. As a result, a good image at the initial stage was maintained to the end, and there was no change on the surface of the developing roller. I was not able to admit. Next, the developing roller of this embodiment was pressed against the photosensitive drum of the developing unit at a pressure of 500 g and left in an atmosphere of 50 ° C. and 85% for 5 days. No change was observed on the photosensitive drum after leaving it.

[Example 2] PR30781 (manufactured by Sumitomo Durez) was used as a resol type phenol resin.
XE2 (Degussa) was used as carbon in a solution prepared by dissolving this in an ethanol solvent to a resin concentration of 10%.
(Manufactured by the company) was mixed for 15 phr with respect to the resin concentration and dispersed for 1 hour with a sand grinder to obtain a coating solution.

The above coating solution was placed in a cylindrical glass container,
A roller-shaped conductive member obtained in the same manner as in Example 1 was immersed therein at a speed of 1 cm / sec and pulled up at the same speed to form a skin layer on the surface of the conductive member, and then at 110 ° C. for 3 hours. The surface layer was crosslinked by heating to obtain a developing roller having a skin layer. In this case, the film forming property of the skin layer was extremely good.

When the surface conductivity of the obtained developing roller was measured, it was 10 ² Ωcm ² , and a sufficiently low resistance was achieved. The hardness of this developing roller was 52 degrees in JIS-A hardness, and the surface roughness was 15 μm in terms of JIS 10-point roughness Rz. Further, when the obtained roller was cut along the axial direction and observed with an optical microscope, it was confirmed that the skin layer was a uniform thin film with a film thickness of about 6 μm. Furthermore, when a predetermined stress was applied to the roller surface to compress the roller surface, the surface skin layer satisfactorily followed the deformation of the roller surface, and no inconvenience such as cracking occurred.

Titanium oxide particles were attached and fixed to the surface of this developing roller in the same manner as in Example 1 to obtain a finished product. When the performance of this developing roller was evaluated in the same manner as in Example 1, excellent image characteristics were obtained. Particularly when solid black printing was performed on the entire surface, there was no difference in density between the front and rear edges, and the toner charging start-up ability was excellent. It was confirmed. The toner charge amount was 20 μC / g. Further, in the 10,000-sheet continuous paper passing test, the initial good image was kept until the end, and no change was observed on the surface of the developing roller.

[Comparative Example 1] A developing roller was obtained in the same manner as in Example 1 except that titanium oxide was not attached to the surface.
When the performance of the obtained developing roller was evaluated in the same manner as in Example 1, some fog was confirmed in the initial image. The toner charge amount was 7 μC / g. Furthermore,
In the continuous paper feeding test, the fog increased and the black density tended to decrease.

[Comparative Example 2] A developing roller was obtained in the same manner as in Example 2 except that titanium oxide was not attached to the surface.
When the performance of the obtained developing roller was evaluated in the same manner as in Example 1, image fog was confirmed in the initial image.
Further, when a black solid image was printed on the entire surface, a slight difference in density between the front and rear edges was observed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a developing roller of the present invention.

FIG. 2 is a schematic sectional view showing an example of the developing device of the present invention.

[Explanation of symbols]

 1 Developing Roller 2 Shaft 3 Elastic Layer 4 Skin Layer 5 Toner Application Roller 6 Photosensitive Drum (Latent Image Holding Body) 7 Toner (Developer) 8 Layering Blade 9 Transfer Section 10 Cleaning Section 11 Cleaning Blade

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Harashima 43-1-206 Sachigaoka, Asahi-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Takahiro Kawagoe 1302-57, Aobadai, Tokorozawa, Saitama Prefecture

Claims (3)

[Claims] 1. An elastic layer having conductivity is formed on the outer circumference of a good conductive shaft, and a developer is carried on the surface to form a thin layer of the developer. In this state, an electrostatic latent image is formed. In a developing roller that supplies a developer to the surface of the latent image carrier by contacting or approaching the latent image carrier held on the surface to visualize the electrostatic latent image, the average particle diameter of the roller surface is 30
A developing roller having metal oxide particles of μm or less adhered and fixed. 2. The developing roller according to claim 1, wherein the metal oxide particles adhered and fixed to the roller surface are titanium oxide. 3. A latent image carrier that holds an electrostatic latent image on its surface and a latent image carrier that contacts or approaches the surface of the latent image carrier with the outer peripheral surface carrying the developer. A developing device comprising a developing roller for supplying the electrostatic latent image to a surface to visualize the electrostatic latent image, wherein the developing roller according to claim 1 or 2 is used as the developing roller.