JPH10123826A - Developing roller and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a developing roller capable of obtaing such images that are not lowered in density and can be surely reproduced as excellent images over a long term, even when it is used for a long time. SOLUTION: An electrical conductive elastic layer 3 is formed on the outside circumference of a good electrical conductive shaft 2. Then, one-component developer is carried on the surface of the layer 3 so as to form the thin layer thereof. By bringing the developing roller into contact with an image forming body or making it proximate to the image forming body in such a state and supplying the developer to the surface of the image forming body, a visible image is formed on the surface of the image forming body. In such a case, the layer 3 is provided with a resin component whose elongation percentage of a break time by the standard of JIS K7113 is <=10% on the surface part.

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, an electrostatic recording apparatus, or the like, a photosensitive drum or belt holding an electrostatic latent image, a sheet of paper, OHP, photographic paper, or the like. Supply a one-component developer to an image forming body such as a class, a developing roller for forming a visible image on the surface of these image forming body and a developing device using the developing roller,
More specifically, the present invention relates to a developing roller having excellent durability and capable of reproducing a good image over a long period of time without lowering the image density even when used for a long period of time, 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 or an electrostatic recording apparatus, a one-component developer is supplied to a latent image holding member such as a photosensitive drum holding a latent image, and a latent image holding member is supplied. As a developing method for visualizing the latent image by attaching the developer to the latent image on the surface, a pressure developing method is known (US Pat. Nos. 3,115,2012 and 3,731,146). According to this method, Since no magnetic material is required, the device can be easily simplified and downsized, and the toner can be easily colored.

In this pressure development method, a developing roller carrying a toner (usually a non-magnetic one-component developer is used) is brought into contact with a latent image holding member such as a photosensitive drum holding an electrostatic latent image. The development is performed by attaching toner to the latent image on the latent image holding member. For this reason, it is necessary to form the developing roller with a conductive elastic material.

That is, in this pressure development method, for example, as shown in FIG. 2, a toner-applying roller 4 for supplying toner and a photosensitive drum 5 holding an electrostatic latent image are provided. The developing roller 1 is provided, and the developing roller 1, the photosensitive drum 5, and the toner applying roller 4 rotate in the directions of arrows in the figure, respectively, so that the toner 6 is applied to the surface of the developing roller 1 by the toner applying roller 4. Supplied,
The toner is formed into a uniform thin layer by the layering blade 7, and the developing roller 1 rotates in contact with the photosensitive drum 5 in this state, so that the toner formed in the thin layer is transferred from the developing roller 1 to the photosensitive drum 5. The latent image is directly attached to the latent image so that the latent image can be visualized. In the drawing, reference numeral 8 denotes a transfer unit, which transfers a toner image to a recording medium such as paper. Reference numeral 9 denotes a cleaning unit, which is provided on the surface of the photosensitive drum 5 after transfer by a cleaning blade 10. The remaining toner is removed.

In this case, the developing roller 1 includes a photosensitive drum 5
It is necessary to rotate while securely maintaining a state of being in close contact with the shaft. Therefore, as shown in FIG.
It has a structure in which a conductive agent is blended into an elastic rubber such as NBR or EPDM, urethane foam, or the like to form an elastic layer 3 made of an elastic body provided with conductivity.

[0006]

However, the conventional developing roller has the following disadvantages due to the characteristics of the elastic layer. 1) When the elastic layer is formed of an elastic rubber such as silicone rubber, NBR, EPDM, etc., if the hardness is reduced to obtain good adhesion, the oil component contained in the rubber bleeds on the roller surface to adhere the toner. The image density may decrease when used for a long period of time. 2) When the elastic layer is formed of a sponge body such as urethane foam, if the toner penetrates into the elastic layer and is used for a long time, the roller becomes hard due to toner clogging or the toner is charged poorly. The concentration may decrease.

Further, when the latent image holding member has a belt shape instead of a drum shape, or when a toner is directly supplied from a developing roller to a recording medium such as paper, OHP, photographic paper, or the like, an image is formed. There is also a forming method, and in such a method, a similar developing roller can be used. In this case, the same problem as described above may occur.

The present invention has been made in view of the above circumstances, and a developing roller capable of reliably reproducing a good image over a long period without a decrease in image density even after a long-term use. And a developing device using the developing roller.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, one component has been formed on the surface of a developing roller having a conductive elastic layer formed on the outer periphery of a good conductive shaft. A developer is carried thereon to form a thin layer of the developer, and the developing roller is brought into contact with or in proximity to an image forming body such as a latent image holding body having an electrostatic latent image held on its surface, thereby forming the image forming body. It has been found that the surface condition of the roller greatly affects the decrease in image density that occurs when a visible image is formed on the surface of the image forming body by supplying the developer to the surface. As a result of further study focusing on the above, it was found that a resin component for improving the surface condition was added to the surface of the elastic layer. In this case, JIS K7
By using a resin component having an elongation at break of 10% or less according to the provisions of 113, it is possible to effectively suppress a decrease in image density and reliably reproduce a good image even for long-term use. It has been found that the quality of the initial image can be improved, and the present invention has been completed.

Accordingly, the present invention comprises forming a conductive elastic layer on the outer periphery of a highly conductive shaft, carrying a one-component developer on the surface of the elastic layer, and forming a thin layer of the developer. In this state, by contacting or approaching the image forming body, by supplying the developer to the surface of the image forming body, a developing roller that forms a visible image on the surface of the image forming body,
A developing roller, wherein the elastic layer has a resin component having an elongation at break of 10% or less according to JIS K7113 on a surface portion thereof, and a one-component developer carried on an outer peripheral surface. A developing device comprising a developing roller for forming a visible image on the surface of the image forming body by causing the one-component developer to adhere to the surface of the image forming body by rotating in contact with or close to the surface of the image forming body; A developing device using the developing roller of the present invention as the developing roller.

The mechanism by which the above-mentioned resin component is applied to the surface of the elastic layer to prevent a decrease in image density due to long-term use is not clear, but is presumed as follows. That is, the elongation at break on the surface of the developing roller is 10%.
% Or less of the resin component having a very low elongation, it is possible to effectively prevent the deformation of the roller surface during development, and the characteristic change of the resin component is extremely small even after long-term use. It is presumed that the above effects can be obtained because a good surface state is maintained. Also,
In the developing roller of the present invention, the charging performance of the developer can be appropriately controlled by appropriately selecting the resin component according to the application and the developer, and a good image can be reliably obtained. is there.

Further, in the developing roller of the present invention, the surface roughness of the elastic layer is changed by applying the resin component to the surface of the elastic layer. Therefore, the present inventor has conducted further studies to ensure proper surface roughness without impairing the effects of the resin component application even after the resin component application, and as a result, the elastic layer base material surface roughness and Optimizing the relationship with the thickness of the resin component applied to the surface of the elastic layer, and maintaining a good surface roughness by forming the resin component having a low elongation ratio thinner than the surface roughness of the base material of the elastic layer. JIS 10 point average roughness R of the substrate surface of the elastic layer
When z is a and the thickness of the resin component applied to the base material surface is b, by adjusting these relations so as to be 0.01 <b / a <2, an appropriate surface roughness can be obtained. It has been found that the chargeability and the durability can be improved while maintaining good developer transportability while maintaining the above-mentioned conditions.

Accordingly, the present invention provides, as a preferred embodiment, a case where the JIS 10 point average roughness Rz of the surface of the base material of the elastic layer is a and the thickness of the resin component applied to the base material surface is b. The developing roller of the present invention, which satisfies the relationship of 0.01 <b / a <2, and the developing device of the present invention using the developing roller are provided.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As shown in FIG. 1, the developing roller of the present invention has a conductive elastic layer 3 formed on the outer periphery of a highly conductive shaft 2. In the present invention, the surface of the elastic layer 3 of the developing roller is used. And a resin component having an elongation at break of 10% or less according to JIS K7113.

As the shaft 2, any shaft having good conductivity can be used, but usually, a metal core made of a metallic solid body and the inside thereof are hollowed out. A metal shaft such as a metal cylinder is used.

Next, the elastic layer 3 formed on the outer periphery of the shaft 2 is made of an elastomer such as polyurethane or EPDM, a foam material, or another resin molded body as a base material. By blending a conductive powder such as powder or an ionic conductive material such as sodium perchlorate, the conductivity is adjusted to an optimum medium resistance range of 10 ³ to 10 ¹⁰ Ωcm, especially 10 ⁴ to
Those adjusted to 10 ⁸ Ωcm are preferred.

In this case, the above-mentioned base material is specifically made of polyurethane, natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber. (EPD
M), chloroprene rubber, acrylic rubber, and mixtures thereof.
Is preferred. Examples of other resins used as the base include phenolic resins, polyesters, polycarbonates, and the like.

The polyurethane used as the base material of the elastic layer 3 will be described. The polyurethane elastomer and the foam material may be any of those produced by various methods. For example, carbon black is blended in a polyurethane prepolymer, It can be obtained by a method of causing a polymer to undergo a crosslinking reaction, a method of blending a conductive material with a polyol, and reacting the polyol with a polyisocyanate by a one-shot method.

Examples of the polyhydroxyl compound used for obtaining the polyurethane include polyols used in the production of general flexible polyurethane foams and urethane elastomers, for example, polyether polyols having a polyhydroxyl group at the end, polyester polyols, and both. In addition to polyether polyester polyol which is a polymer, polyolefin polyols such as polybutadiene polyol and polyisoprene polyol, and general polyols such as a so-called polymer polyol obtained by polymerizing an ethylenically unsaturated monomer in a polyol include Can be used. Examples of the polyisocyanate compound include polyisocyanates which are also used for producing general flexible polyurethane foams and urethane elastomers, that is, tolylene diisocyanate (TDI), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI, aliphatic polyisocyanates having 2 to 18 carbon atoms, 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, etc. Used.

On the other hand, EPDM is a terpolymer composed of ethylene, propylene and a third component. The third component is not particularly limited, but may be dicyclopentadiene, ethylidene norbornene, 4-hexadiene or the like is 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 amount is preferably from 0 to 50 in iodine value. Note that two or more types of EPDM having different iodine values can be used in combination. The above-mentioned EPDM may be used by blending silicone rubber or silicone-modified EPDM or both. In this case, the mixing amount of the silicone rubber and the silicone-modified EPDM can be 5 to 80 parts by weight based on 100 parts by weight of the EPDM. The silicone-modified EPDM refers to a hybrid rubber in which the bonding force between both EPDM and silicone polymers is increased via a silanol compound or siloxane.

Further, a crosslinking agent and a vulcanizing agent can be added to crosslink the elastic layer into a rubbery substance. In this case, a vulcanization aid, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanization retarder, and the like can be used in both cases of organic peroxide crosslinking and sulfur crosslinking. Furthermore, peptizing agents, foaming agents, plasticizers, softeners, tackifiers, antiblocking agents, separating agents, release agents, extenders, and coloring agents that are commonly used as rubber compounding agents in addition to the above. Etc. can be added.

When the elastic layer 3 is formed using polyurethane or EPDM as a base material, for example, nigrosine, triaminophenylmethane, a cationic dye, etc., for the purpose of controlling the amount of toner charge on the surface when used as a developing roller. Various charge control agents, fine powders of silicone resin, silicone rubber, nylon and the like can be added. In this case, the amount of these additives is preferably 1 to 5 parts by weight, and the fine powder is preferably 1 to 10 parts by weight, based on 100 parts by weight of the polyurethane or EPDM.

Next, as a conductive material used for imparting conductivity to the elastic layer 3, powdery conductive materials such as Ketjen Black EC and acetylene black, SAF, ISAF , HAF,
Carbon for rubber such as FEF, GPF, SRF, FT, MT, carbon for color (ink) which has been oxidized, etc.
Metals such as pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium, and metal oxides, and conductive polymers such as polyaniline, polypyrrole, and polyacetylene. Can be Among them, carbon black is inexpensive and easily controls conductivity in a small amount. These conductive powders are usually made of urethane or EP.
It is suitably used in the range of 0.5 to 50 parts by weight, particularly 1 to 30 parts by weight, based on 100 parts by weight of a base material such as DM.

Examples of the ionic conductive substance used as the conductive material include inorganic ionic conductive substances such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride; Examples thereof include organic ionic conductive materials such as ammonium ethosulfate, stearyl ammonium acetate, lauryl ammonium acetate, octadecyltrimethylammonium perchlorate, and tetrabutylammonium borate.

In the present invention, although the elastic layer 3 is not particularly limited, the elastic layer 3 has a resistance value of 10 ³ Ωcm to 10 ¹⁰ Ωcm, particularly 10 ⁴ ΩΩ to 10 ⁸ ΩΩ, depending on the composition of the conductive material.
cm is preferable. Charge and the resistance value is less than 10 ³ [Omega] cm is or leak into the image forming member such as a photosensitive drum, there is a case where the developing roller itself or destroyed by voltage, whereas when it exceeds 10 ¹⁰ [Omega] cm, earth developed image Fogging is likely to occur.

The hardness of the elastic layer 3 is not particularly limited. However, when the developing roller is brought into contact with a latent image holding member such as a photosensitive drum or an image forming member such as paper sheets to perform development. Is 60 ° or less on the JIS-A scale, especially 25 to
Preferably, it is 55 °. In this case, the hardness is 60 °
Exceeding the contact area of the image forming body becomes small, and good development may not be performed.On the contrary, when the hardness is too low, the compression set becomes large, and the developing roller is deformed or eccentric for some reason. In this case, uneven image density occurs. For this reason, even when the hardness of the elastic layer is set to be low, it is preferable to reduce the compression set as much as possible, specifically, it is preferable to set the compression set to 20% or less.

In the developing roller of the present invention, a resin component having an elongation at break of 10% or less according to JIS K7113 is applied to the surface of the elastic layer 3.

The resin component is not particularly limited as long as it has the above-mentioned elongation and is non-contaminating with respect to a latent image holding member such as a photosensitive drum or an image forming member such as paper sheets. Although not limited, urea resin, melamine resin, alkyd resin, modified alkyd resin such as phenol-modified / silicone-modified, oil-free alkyd resin, acrylic resin, silicone resin, fluorine resin, phenol resin, polyamide resin, epoxy resin, polyester resin , Maleic acid resin, urethane resin and the like. Among them, urea resin, melamine resin, silicone resin, phenol resin,
One or two or more resins selected from alkyd resins, various modified alkyd resins, oil-free alkyd resins, acrylic resins and moisture-curable urethane resins are suitably used, and among them, various modified alkyd resins or oil-free alkyd resins and melamine A resin mixed with a resin or a phenol resin is preferably used because of its low elongation and high mechanical strength. In addition, melamine resins are preferably used because they have an electron supply property due to unpaired electrons of the nitrogen group in the resin, and phenol resins are preferably used because they have electronic dielectric properties due to their high dielectric constant. Is done.

Here, the resin component is J as described above.
10% elongation at break according to IS K7113
The following, preferably 5% or less is used. In this case, if the elongation at break exceeds 10%, the roller surface will be deformed during long-term use, resulting in poor transport of the developer and the like, resulting in a decrease in the density of the obtained image.

The resin component may or may not contain a conductive material, and can be appropriately selected according to adjustment of roller resistance and the like. Note that, although not particularly limited, when a conductive material is added, the above-described conductive powder is suitably used, and carbon black is particularly preferably used.

As a means for applying such a resin component to the surface of the elastic layer, a method of surface-treating the elastic layer of the roller with a resin solution containing the above resin component is suitably employed. In this case, the surface treatment is performed by spraying after preparing the resin solution,
It can be performed by a roll coater method, a dipping method, or the like. For example, for the surface treatment by dipping, a method of dipping in a resin solution having the above concentration at room temperature for 5 seconds to 5 minutes, preferably for 10 seconds to 1 minute, pulling it up, and drying it can be adopted. When the spray method is employed, the concentration of the resin in the processing solution can be set higher than that of the dipping method, and for example, a resin whose concentration is adjusted to 10 to 30% can be used. The solvent for preparing the resin solution may be any solvent as long as it dissolves the above resin. Usually, lower alcohols such as methanol, ethanol, and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; toluene,
Xylene or the like is preferably used.

Although the surface treatment with the above resin component can reduce the friction of the roller surface to some extent, various additives can be used to further reduce the friction. In this case, silicone resin, silicone resin powder, fluorine-based and silicone-based surfactants, silicone-based surfactants can be used as additives capable of reducing friction without causing contamination of the photoreceptor and reducing the uniformity of the surface treatment. Coupling agents and silica powder are preferably used.

Examples of the silicone resin include those soluble in solvents, for example, methyl silicone, methyl phenyl silicone, modified products thereof, and silicone epoxy block copolymer.

As the silicone resin powder, for example, methyl silicone or methyl phenyl silicone polymer,
Examples include fine powder of an amino group-modified silicone polymer, and those having a true spherical shape and an amorphous shape having an average particle size of 0.1 to 100 μm are preferably used.

As the fluorinated surfactant, an ionic surfactant in which an alkyl fluoride is bonded to a carboxylic acid, a carboxylate, a sulfonate, or the like, or a nonionic surfactant in which an alkyl fluoride is bonded to an alcohol, an ether, or the like. And polymer-based polymers such as polymers and copolymers containing alkyl fluoride in the side chain and main chain.

Examples of the silicone-based surfactant include high-molecular-weight surfactants such as conjugates of methyl silicone such as siloxane oxyethylene with hydrophilic and lipophilic segments, and copolymers of methyl silicone and acrylic segments. Things.

As the silicon-based coupling agent, not only an ordinary silane coupling agent but also an amino group at the terminal,
Includes silanes into which isocyanate groups, vinyl groups, etc. have been introduced.

These may be used alone or in combination of two or more. In addition, a fluororesin also effectively acts as a friction reducing agent. The amount of the friction reducing agent to be used is 1 to 100 parts by weight, preferably 10 to 75 parts by weight, based on 100 parts by weight of the resin component. When an ionic conductive material is used as the conductive material, the amount of the ionic conductive material to be added to the resin solution is adjusted by the amount of the resin component 10.
It is preferably 0.001 to 1 part by weight based on 0 part by weight.

Here, in the developing roller of the present invention, although not particularly limited, the surface roughness of the base material of the elastic layer 3,
That is, the surface roughness of the elastic layer 3 before applying the resin component to the surface is a (JIS 10 point average roughness Rz), and the thickness of the resin component applied on the elastic layer base material is b (μm ), It is preferable to adjust the surface roughness of the substrate surface of the elastic layer 3 and the thickness of the resin component so as to satisfy the relationship of 0.01 <b / a <2. The chargeability and durability can be improved while maintaining an appropriate surface roughness and maintaining good developer transportability. In addition,
If b / a ≧ 2, the surface roughness may be low and the toner transport amount may be insufficient, while if b / a ≦ 0.01, the durability is reduced and the effect of the present invention is sufficiently achieved. May not be obtained.

In this case, the surface roughness a of the base material of the elastic layer and the thickness b of the resin component need only satisfy the above relationship, and are not particularly limited. Roughness a, that is, JIS 10-point average roughness Rz of the substrate surface
Is 30 μm or less, particularly 0.1 to 30 μm,
It is preferable that the thickness is about 15 μm. On the other hand, the thickness b of the resin component may be a thickness that satisfies the above relationship with respect to the preferable surface roughness Rz (a), and specifically, is 0. It is preferably about 1 to 20 μm, particularly about 1 to 10 μm. The elastic layer 3 after the application of the resin component
The surface roughness of the developing roller of the present invention, that is, the surface roughness of the developing roller of the present invention is not particularly limited.
Is preferably 15 μm or less, particularly preferably 1 to 10 μm.

Here, the resin component applied to the surface of the elastic layer 3 by the above-mentioned surface treatment, even if it is in the form of a film that covers the entire surface of the elastic layer 3, is a concave portion having minute irregularities on the surface of the elastic layer 3. It may be in a dispersed state in which a resin component is provided therein, or may be in a state in which most of the surface of the elastic layer 3 is covered and the tips of the convex portions of the fine irregularities on the surface of the elastic layer 3 are partially exposed. . In this case, the thickness b of the resin component is an average thickness of the resin component provided on the surface of the elastic layer 3 in these various forms, and can be measured by the following method. For example, the elastic layer (1 cm × 1 cm) to which the resin component was applied was sampled from several places of the roller, the cross section of the elastic layer was observed, the thickness of each resin was measured, and the total of these thicknesses was measured. It is obtained by dividing by the number of elastic layer pieces. Means for observing the thickness of the resin component is not particularly limited, and a known means such as an electron or optical microscope can be used.

The developing roller of the present invention can be incorporated in an ordinary developing device using a one-component developer, and more specifically, as shown in FIG. The developing roller 1 of the present invention is disposed between the photosensitive drum 5 holding the electrostatic latent image and the toner 6 is supplied to the developing roller 1 by the toner applying roller 4, and the toner 6 is uniformly thinned by the layering blade 7. The toner is supplied to the photosensitive drum 5 from the thin layer, and the toner is adhered to the electrostatic latent image on the photosensitive drum 5 to visualize the latent image. In this case, in FIG. 2, the surface of the developing roller 1 is in contact with the photosensitive drum 5, but the developing roller of the present invention does not necessarily have to be in contact with the image forming body such as the photosensitive drum 5. The developing roller 1 and the photosensitive drum 5 may be in a non-contact proximity state as long as the toner can be transferred. Since the details of FIG. 2 have been described in the related art, the description thereof is omitted.

The developing roller of the present invention is preferably used when an electrostatic latent image held on the surface of the photosensitive drum 5 is visualized with a one-component developer as shown in FIG. The image forming body that forms a visible image by supplying a developer with the developing roller of the present invention is not limited to the above-described photosensitive drum, and a latent image holding body other than a drum shape such as a belt shape, and further a recording medium The present invention can be suitably applied to an application in which a developer is directly supplied to paper sheets such as paper, OHP, and photographic paper as a medium to form a visible image on these paper sheets. For example, as in a mechanism disclosed in Japanese Patent Application Laid-Open No. 8-129293, in a state where a back electrode roller is disposed on the back side of paper such as paper or OHP, a developer is applied to the front side of the paper sheet. By bringing the carried developing roller close to and flying the developer on the developing roller toward the back electrode roller while controlling the developer on the aperture electrode, the paper disposed between the back electrode roller and the developing roller is controlled. The developing roller of the present invention can also be suitably used as a developing roller that supplies a developer to leaves to form a visible image on the paper sheet,
Also in this case, by using the developing roller of the present invention,
The image density can be effectively prevented from lowering due to long-term use, and a good image can be reliably reproduced over a long period of time.

As the one-component developer used when the development is performed using the developing roller of the present invention, a non-magnetic one-component developer is preferably used. The developing roller and the developing device of the present invention can also be suitably used, for example, when printing black and white images using a magnetic one-component developer.

[0045]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, the surface treatment was performed by immersing in a treatment solution at room temperature for 30 seconds.

Example 1 Glycerin was added with propylene oxide and ethylene oxide to give a molecular weight of 500
100 parts by weight of polyether polyol (Exenol 828 from Asahi Glass Co., Ltd.) (OH value: 33) (parts by weight,
The same applies hereinafter), 1.0 part of 1,4-butanediol, and a silicone surfactant (L-520, manufactured by Nippon Yunika).
5 parts, 0.5 parts of nickel acetylacetonate, 0.01 parts of dibutyltin dilaurate and 2.0 parts of acetylene black (manufactured by Denka) are added, preliminarily mixed using a mixer, and kneaded with a paint roll. Thus, acetylene black was uniformly dispersed to prepare a polyol composition.

The polyol composition was stirred under reduced pressure to remove bubbles, and then 17.5 parts of urethane-modified MDI (Sumitomo Bayer Urethane Co., Ltd., Sumidur PF) was added, followed by adding 2 parts.
Stir for a minute and then pour into a mold heated to 110 ° C.
After curing for 2 hours, an elastic layer was formed on the outer periphery of the metallic shaft to obtain a roller having the structure shown in FIG. The developing roller was prepared by polishing the surface of the obtained roller. The JIS 10-point average roughness Rz of the roller surface was 7.0 μm.

Next, a mixed resin obtained by mixing an oil-free alkyd resin and a melamine resin (in this order, Beccolite M-6402 and Super Beckamine L110, both manufactured by Dainippon Ink and Chemicals, Inc.) at a ratio of 4: 1 was mixed in toluene. To 10
A resin solution was prepared by dissolving the solution in a concentration by weight, and the developing roller was immersed in the resin solution, pulled up, heated and dried, and subjected to a surface treatment. When the fracture surface of this roller was observed, the thickness of the mixed resin applied to the roller surface by the surface treatment was 5 μm (average value, the same applies hereinafter).
Met.

On the other hand, using a mixed resin of the above oil-free alkyd resin and melamine resin, JIS K7113
Prepare the first type test piece specified in JIS K71
When a tensile test was performed according to the provisions of Example 13, the elongation at break was less than 3%.

Example 2 The same as Example 1 except that the surface treatment was performed using a resin solution in which a resol type phenol resin PR50232 (manufactured by Sumitomo Durez) was dissolved at a concentration of 10% by weight in a methyl ethyl ketone solvent. To form a developing roller. When the fracture surface of this roller was observed, the thickness of the phenol resin applied to the roller surface by the surface treatment was 2 μm.

On the other hand, using the above phenol resin, JIS
Prepare the first test piece specified in K7113,
When a tensile test was performed in accordance with IS K7113, the elongation at break was less than 3%.

Example 3 Carbon black Printix 35 as a conductive agent in a phenol resin for surface treatment
Example 2 except that 20 phr (manufactured by Degussa) was added.
A developing roller was prepared in the same manner as described above. Observation of the fracture surface of this roller revealed that the thickness of the phenol resin to which the carbon black was added, which was applied to the roller surface by the surface treatment, was 3 μm.

On the other hand, a first type test piece specified in JIS K7113 was prepared using the phenol resin to which the carbon black was added, and a tensile test was performed in accordance with JIS K7113. 3
%. When the resistance value of this resin was measured, it was 10 ⁴ Ωcm, and it was confirmed that the resin was rendered conductive by the addition of carbon.

Example 4 A developing roller was prepared in the same manner as in Example 1 except that the surface treatment by dipping was repeated several times to increase the thickness of the resin applied to the roller surface. When the fracture surface of this roller was observed, the thickness of the resin applied to the roller surface by the surface treatment was 2
It was 0 μm. The resistance value of this roller was measured by the following method and found to be 10 ¹¹ Ω, indicating that the roller surface was almost completely covered with resin.

Comparative Example 1 Soluble Copolymer Nylon CM8
000 (manufactured by Toray Industries Co., Ltd.) in a concentration of 15% by weight in methanol, except that the surface treatment was performed using a resin solution.
A developing roller was prepared in the same manner as in Example 1. When the fracture surface of this roller was observed, the thickness of the nylon applied to the roller surface by the surface treatment was 5 μm.

On the other hand, a first type test piece specified in JIS K7113 was prepared using the above soluble copolymerized nylon, and a tensile test was performed in accordance with JIS K7113. The elongation at break was 100% or more. Met.

Comparative Example 2 A developing roller was prepared in the same manner as in Example 1 except that the surface treatment was not performed.

The following characteristic tests were performed on the developing rollers obtained in the above Examples and Comparative Examples. Table 1 shows the results. (1) Roller Resistance Each roller was pressed against both ends of a copper plate with a load of 500 g applied thereto, and measured by applying a voltage of 100 V using a resistivity meter R8340A (manufactured by Advantest). (2) Image Output Each roller is attached to the developing unit shown in FIG. 2 as a developing roller, and a non-magnetic one-component toner having an average particle size of 7 μm is used. The reverse development is performed while rotating at a peripheral speed of a linear speed of 60 mm / sec. Image output was repeated to evaluate the image quality.

[0059]

[Table 1]

As is clear from Table 1, according to the developing roller of the present invention, it is possible to effectively suppress a decrease in image density even for a long-term use and to reliably reproduce a good image, It was also confirmed that the image quality was excellent. In addition, the rollers of Examples 1 to 3 in which the surface roughness (a) of the base material of the elastic layer and the thickness (b) of the resin component on the surface were optimized were excellent in developer transportability and excellent density. It was confirmed that images could be obtained reliably. After the image forming test, the developing roller of Comparative Example 1 was taken out, and the surface thereof was observed with a microscope. The surface morphology was greatly changed, and the nylon existing on the surface was elongated and the surface was smoothed. It was confirmed that. As a result, it is considered that the transport of the developer was insufficient and the density was reduced.

[0061]

As described above, according to the developing roller and the developing device using the same according to the present invention, a good image can be surely obtained by effectively suppressing a decrease in image density even for long-term use. And the quality of the initial image can be improved.

[Brief description of the 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]

 DESCRIPTION OF SYMBOLS 1 Developing roller 2 Shaft 3 Elastic layer 4 Toner application roller 5 Photosensitive drum (latent image holding body) 6 Toner (one-component developer) 7 Layering blade 8 Transfer part 9 Cleaning part 10 Cleaning blade

Claims (6)

[Claims] An elastic layer having conductivity is formed on the outer periphery of a good conductive shaft, and a one-component developer is carried on the surface of the elastic layer to form a thin layer of the developer. In a developing roller for forming a visible image on the surface of the image forming body by supplying the developer to the surface of the image forming body in contact with or in proximity to the image forming body, the elastic layer has a JIS on a surface portion thereof. A developing roller comprising a resin component having an elongation at break of 10% or less according to K7113. 2. When the JIS 10-point average roughness Rz of the surface of the substrate of the elastic layer is a and the thickness of the resin component applied to the surface of the substrate is b, 0.01 <b / a <2. The developing roller according to claim 1, wherein the following relationship is satisfied. 3. The resin component is selected from a urea resin, a melamine resin, an alkyd resin, a modified alkyd resin, an oil-free alkyd resin, an acrylic resin, a silicone resin, a phenol resin, and a moisture-curable urethane resin.
The developing roller according to claim 1, wherein the developing roller contains one or more kinds. 4. The method according to claim 1, wherein a one-component developer is supplied to a surface of the latent image holding member holding the electrostatic latent image on the surface to visualize the electrostatic latent image. The developing roller according to the above item. 5. The image forming apparatus according to claim 1, wherein the one-component developer is brought into contact with or close to the surface of the image forming body while the one-component developer is carried on the outer peripheral surface, and the one-component developer is attached to the surface of the image forming body. A developing device comprising a developing roller for forming a visible image on a body surface, wherein the developing roller according to claim 1 is used as the developing roller. 6. The developing device according to claim 5, wherein a one-component developer is supplied to a surface of the latent image holding member holding the electrostatic latent image on the surface to visualize the electrostatic latent image.