JP3052749B2 - Developer carrying member and electrophotographic apparatus using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin film of a developer by carrying a developer on the surface, and in this state, contacting a latent image holding member holding an electrostatic latent image on the surface to remove the electrostatic latent image from the thin film. The present invention relates to a developer carrying member for adhering the developer to a surface of a latent image holding member to visualize the electrostatic latent image, and an electrophotographic apparatus using the developer carrying member.

[0002]

2. Description of the Related Art Conventionally, in a conductive member, for example, in an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus, a non-magnetic one-component developer is supplied to a photosensitive drum holding a latent image, and the photosensitive drum is supplied. As a developing method for visualizing the latent image by attaching the developer to the latent image, a pressure developing method is known (U.S. Pat.
According to this method, no magnetic material is required, so that the apparatus can be easily simplified and downsized, and the toner can be easily colored.

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

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 disposed in contact with the photosensitive drum 5 and slightly apart from the toner coating roller 4. The developing roller 1, the photosensitive drum 5 and the toner coating roller 4 are respectively arranged in the directions indicated by arrows in FIG. By the rotation, the toner 6 is supplied to the surface of the developing roller 1 by the toner applying roller 4, and the toner is adjusted to a uniform thin layer by the layering blade 7, and the developing roller 1 contacts the photosensitive drum 5 in this state. By rotating while rotating, the toner formed in a thin layer adheres to the latent image on the photosensitive drum 5 from the developing roller 1 and the latent image is visualized. In addition,
In the drawing, reference numeral 8 denotes a transfer unit, which transfers a toner image onto a recording medium such as paper. Reference numeral 9 denotes a cleaning unit, which remains on the surface of the photosensitive drum 5 after transfer by a cleaning blade 10. The 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. Further, it has been proposed to provide a surface layer provided with conductivity by blending a conductive powder on the elastic layer 3 for the purpose of improving the surface friction property, image quality and the like.

[0006]

However, the conventional conductive developing roller has the following disadvantages. 1. When a single elastic layer is formed of silicone rubber, urethane elastomer, etc., when the hardness is reduced to obtain good adhesion, not only contamination of the photosensitive drum occurs but also a suitable surface roughness is obtained. Polishing becomes difficult. 2. Not only in the case of a single layer, but also in the case of providing a surface layer containing a conductive powder, the resistance of the elastic layer is 10 ⁵ to 10 ⁸ Ωcm.
It is difficult to control the resistance. 3. When the resistance of the surface layer is controlled by the conductive powder, the resistance tends to be partially non-uniform, so that uneven density occurs in halftone or the like. 4. It is difficult to stably produce a coating material for providing a surface layer having a uniform resistance.

Further, a conductive developing roller composed of a single elastic layer generally has insufficient charging rise characteristics of toner on the roller, and has problems such as fog due to poor charging of toner, cleaning failure due to selection phenomenon, and print density reduction. And print quality is significantly reduced by long-term continuous printing. This phenomenon is particularly remarkable under a high temperature and high humidity environment.

The present invention has been made in view of the above circumstances, and provides not only low hardness and good adhesiveness, but also a low-friction, high-quality image without contamination of a photoreceptor and the like. It is an object of the present invention to provide a developer-carrying member that does not cause a variation in performance in terms of manufacturing, and an electrophotographic apparatus using the member.

[0009]

Means for Solving the Problems The present inventors have developed a developing member used in an electrophotographic apparatus, that is, a developer carrying member, from an elastic material having a volume resistivity ρ1 of 10 ⁷ Ωcm or less on a conductive support. A first coating layer having a volume resistivity ρ2 satisfying ρ2 / ρ1 ≧ 1000, and further containing any one of the main components of a soluble nylon, a urethane-modified acrylic resin, a modified polycarbonate, and a fluororesin which does not contain a conductive powder. By forming the second coating layer, a developer having low hardness and good adhesion, not contaminating the photoreceptor and the like, having low friction and causing no variation in performance in terms of production. It has been found that a supporting member can be obtained. Further, when the surface roughness R of the first coating layer is 3 to 15 μm in JIS 10-point roughness Rz and the thickness of the second coating layer is d, by satisfying 0.1 <d <3 × R It has been found that a high-quality image free from fog and density unevenness can be obtained, and the present invention has been accomplished.

Hereinafter, the present invention will be described in detail. In the present invention, the first coating layer is made of polyurethane or EPDM.
Elastomers and foam materials such as carbon black, metals, metal oxide powders and other conductive powders and ionic conductive substances such as sodium perchlorate 10 ³ to 10 ⁷ Ωcm, especially 10 ⁴ to 10 ⁷ Ωc
Those adjusted to m are preferred.

In this case, the base material is polyurethane, natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber,
Examples thereof include polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, and mixtures thereof, with polyurethane and EPDM being particularly preferred.

First, polyurethane is described. The polyurethane elastomer and the foam material may be any of those produced by various methods. For example, a method in which carbon black is blended in a polyurethane prepolymer and the prepolymer is subjected to a crosslinking reaction. A conductive material can be blended and the polyol can be obtained by a method such as a method of reacting the polyol with a polyisocyanate by a one-shot method.

As the urethane used as the base material of the first coating layer, as a polyhydroxyl compound, a polyol used for producing a general flexible polyurethane foam or a urethane elastomer, for example, a polyether polyol having a polyhydroxyl group at a terminal, Polyester polyols, and polyether polyester polyols which are a mixture of both, and polyolefin polyols such as polybutadiene polyols and polyisoprene polyols, and so-called polymer polyols obtained by polymerizing ethylenically unsaturated monomers in polyols Common polyols 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, carbon number 2-1
For example, aliphatic polyisocyanate No. 8, alicyclic polyisocyanate 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.

On the other hand, EPDM is a terpolymer composed of ethylene, propylene and a third component in this case. The third component is not particularly limited, but may be dicyclopentadiene, ethylidene norbornene, or the like. 1,4-hexadiene and the like are preferably used. The proportions of the above-mentioned ethylene, propylene and the third component are not particularly limited, but the ethylene content is 5 to 95%.
It is preferable that the content of propylene is 5 to 95% by weight, and the content of the third component is 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 is EP
It can be 5 to 80 parts by weight based on 100 parts by weight of DM. 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, in addition to the above, a peptizing agent, a foaming agent, which is generally used as a compounding material for rubber,
Plasticizers, softeners, tackifiers, antiblocking agents, separating agents, release agents, extenders, coloring agents, and the like can be added.

The elastic layer mainly composed of polyurethane or EPDM is charged with various charged materials such as nigrosine, triaminophenylmethane and cationic dye for the purpose of controlling the amount of toner charge on the surface when used as a developing member. A fine powder such as a control agent, silicone resin, silicone rubber, or nylon can be added. In this case, the additive amount of these additives depends on the polyurethane or EPDM1.
The charge control agent is 1 to 5 parts by weight with respect to 00 parts by weight,
The fine powder is preferably used in an amount of 1 to 10 parts by weight.

Examples of the conductive material include conductive carbon such as Ketjen Black EC and acetylene black, SAF, ISAF, HAF, and FE.
Rubber carbon such as F, GPF, SRF, FT, MT, etc.
Metals and metal oxides such as color (ink) carbon, 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 polyaniline, polypyrrole, and polyacetylene. Among them, carbon black is inexpensive and easily controls conductivity in a small amount. Usually, 0.5 to 5 parts per 100 parts by weight of urethane.
It is preferably used in an amount of 0 parts by weight, particularly in the range of 1 to 30 parts by weight.

Examples of ion conductive substances include sodium perchlorate, lithium perchlorate, calcium perchlorate,
Inorganic ionic conductive materials such as lithium chloride and organic ionic conductive materials such as modified aliphatic dimethylammonium ethosulfate, stearyl ammonium acetate, lauryl ammonium acetate, octadecyltrimethylammonium perchlorate, tetrabutylammonium borate, etc. Is exemplified.

In the present invention, the second coating layer is the uppermost layer of the developing member and is a layer which comes into contact with the toner, so that it has good releasability from the toner, and its volume resistivity ρ2 is 1 % of the volume resistivity of the elastic layer. It is required that ρ2 / ρ1 ≧ 1000. When ρ2 / ρ1 <1000, it is not only difficult to set the developing member to 10 ⁵ Ωcm to 10 ⁸ Ωcm, but also it is easy for leakage to occur when voltage is applied. This skin layer must also have flexibility so that cracks and the like do not occur when the developing member is compressed. More specifically, the dynamic elastic modulus at room temperature may be 6 × 10 ⁹ dyn / cm ² or less.

Furthermore the thickness d of the skin layer, when the surface roughness of the first coating layer was R, needs to be in the range of 3~15μm in R _z is 0.1 <d <3 × R Is done. The surface of the developing member needs to have a certain degree of surface roughness to transport the toner.
When xR, the surface roughness of the second coating layer becomes 3 μm or less, and the conveyance of the toner becomes uneven. d depends on R _z , but is preferably 1 to 20, more preferably 3
About 10 μm.

Examples of the resin having the above-mentioned desirable properties for the second coating layer include soluble nylon, urethane-modified acrylic resin, modified polycarbonate, and fluororesin.

Here, the soluble nylon refers to a polymer which is soluble in a general organic solvent by copolymerizing a different type of polyamide unit with ordinary nylon 6, nylon 66, or the like, or chemically modifying an amide group. Nylon. Many copolymerized nylons are alcohol-soluble by terpolymerization, for example, 6/66/12 and 6/66/6.
10/12, 6/610/11/12 nylon and the like.

As the modified nylon, N-methoxymethylated nylon, N-ethoxyethylated nylon or the like in which the hydrogen of the amide group is substituted with an alkoxyl group are used. In addition, the urethane-modified acrylic resin is obtained by introducing a urethane component to the acrylic resin to impart flexibility and flexibility.

As a method of modifying the acrylic resin with a urethane component, it is effective to chemically bond the urethane resin and the acrylic resin component from the viewpoint of compatibility, liquid stability, film flexibility and the like. . Specifically, a reaction of a polymer having a hydroxyl group introduced into an acrylic polymer with a urethane prepolymer having an isocyanate group at a molecular terminal by β-hydroxyethyl methacrylate or the like or a molecular terminal as described below (one terminal, both terminals) ) Is synthesized by the reaction of an acrylic component having a hydroxyl group with a urethane prepolymer (A: acrylic acid, acrylate monomer or oligomer).

Embedded image

The urethane-modified acrylic resin of the present invention is not limited to the above-mentioned method, but may also be a method of adding a diisocyanate to an acrylic diol mixed system,
It can also be obtained by adding an isocyanate polyester or polyether at both ends to an acrylic monomer and polymerizing the urethane acrylate. Further, the glass transition temperature T _g is at room temperature as acrylic resin component used in these synthetic polymers about 8
Those having a temperature of up to 0 ° C. are preferred, and those containing, for example, ethyl methacrylate, isobutyl methacrylate, glycidyl methacrylate, etc. in addition to the above β-hydroxyethyl methacrylate are used. In this case, the composition of the acrylic component in the urethane-modified acrylic resin is 5
It is preferably from 90 to 90% by weight, particularly preferably from 20 to 80% by weight, particularly preferably from 50 to 70% by weight.

Further, the modified polycarbonate used in the present invention is not limited to the bisphenol A type represented by the following general formula (1), but also has the structure represented by the following general formulas (2) and (3). A polymer containing a repeating unit is preferably used. Although the degree of polymerization is not particularly limited, it is generally 10 to 1000, preferably about 50 to 200.

[0027]

Embedded image (However, R ₁ , R ₂ , R ₃ , and R ₄ represent a hydrogen atom, a substituted or unsubstituted aliphatic group, a carbocyclic group, or an aromatic group, and R ₅ , R ₆ , R ₇ , R ₈ , R _{9, R 10, R 11,} R 12
Represents a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic group or a carbocyclic group, and Z represents an atomic group necessary for forming a substituted or unsubstituted carbocyclic or heterocyclic ring. Further, m is an integer of 0 to 10, n is 0 or 1, and p of A and B is an integer of 1 to 10. )

Here, these polycarbonates are easily synthesized, for example, by reacting a diol compound represented by the following formula (4) with phosgene in a methylene chloride solution in the presence of an alkali.

Embedded image The structure of the polycarbonate that can be used in the present invention is not limited to those described above, and may be a copolymer of these, or a copolymer with another aliphatic or aromatic diol compound.

As the fluororesin used in the present invention, general fluorine-containing polymers such as polytetrafluoroethylene and polyvinylidene fluoride are used, and particularly, a solvent-soluble fluororesin is preferably used. Examples of the solvent-soluble fluororesin include CH ₂ CF ₂ , C ₂ F ₄ , and C ₃ F ₆
Vinylidene fluoride copolymers such as terpolymers of C ₂ F ₄
, Fluoroolefin and a vinyl ether such as C ₂ F ₃ Cl, vinyl esters, copolymers of hydrocarbon olefins vinylsilane such, the various copolymers and perfluoroalkyl group and copolymers of fluoroacrylate and acrylate A polymer of a substituted diepoxy compound or the like is used. These resins may be used alone as the resin component of the present invention, or may be used as a mixture with other resins.

These resin films have a certain degree of conductivity and can be used alone. To further add conductivity, the above-mentioned ionic conductive substance, charge transfer complex, etc. can be added.

The charge transfer complex imparts conductivity to tetracyanoethylene and / or a derivative thereof, tetracyanoquinodimethane and / or a derivative thereof, benzoquinone and / or a derivative thereof, chloranil and / or a derivative thereof, anthraquinone and a derivative thereof. And / or its derivatives, anthracene and / or its derivatives, dichlorodicyanobenzoquinone and / or its derivatives, ferrocene and / or its derivatives, phthalocyanine and / or its derivatives, tetrathiafulvalene and / or its derivatives, etc. It is done by substance. These can be used alone, but they may be used in combination of two or more, or even in combination with the ionic conductive material.

As a method of forming the second coating layer, a solvent and, if necessary, a conductive substance are added to adjust the concentration of the coating solution, and then a spray method, a roll coater method, a dipping method, an extrusion method, or the like is used. Formed on the first coating layer. At this time, if necessary, a primer can be used to improve the adhesion between the first coating layer and the second coating layer.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The conductive agent carrier (developing member) of the present invention will be described below.
Examples and devices using the members will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples. (Example 1) 100 parts (parts by weight, hereinafter the same) of polyether polyol (Asahi Glass Co., Ltd .: Exenol 828, OH value 33) having a molecular weight of 5,000 by adding propylene oxide and ethylene oxide to glycerin were added to 1,4 -10 parts of butanediol, 1.5 parts of a silicone surfactant (L-520, manufactured by Nippon Yunika), 0.5 parts of nickel acetyl acetate, 0.01 part of dibutyltin dilaurate, and acetylene black (Denka, pH 6.0). 9) 4.
After adding 0 parts and preliminarily mixing using a mixer, the mixture was kneaded with a paint roll to uniformly disperse acetylene black, thereby preparing a polyol composition.

After the polyol composition was stirred under reduced pressure to remove bubbles, 17.5 parts of urethane-modified MDI (Sumijur PF, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was added and 2 parts were added.
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 metal shaft to obtain a roller having the structure shown in FIG. The surface of the obtained roller is polished and the surface is JIS10-point average roughness 7 μmR
Adjusted to _z to form the first coating layer. At this time, a sheet sample having a thickness of 3 mm was prepared at the same time, and the volume resistivity was measured to be 3.5 × 10 ³ Ωcm. Next, the above roller is mixed with soluble nylon (CM800) in methanol.
0, a volume resistivity of 5 × 10 ¹³ Ωcm, manufactured by Toray Industries, Inc.) was immersed in a solution in which 10% by weight was dissolved, pulled up and dried to form a second coating layer of about 5 μm. At this time, the roller resistance was 3 × 10 ⁷ Ω and R _z was 5 μm.

Example 2 Instead of soluble nylon, urethane-modified acrylic (EAV-8B, volume resistivity 8 × 1)
A roller was made in the same manner as in Example 1 except that a second coating layer of about 5 μm was formed using a 10% by weight MEK / toluene solution (0 ¹² Ωcm, manufactured by Asia Industry Co., Ltd.). At this time, the roller resistance was 5 × 10 ⁶ Ω, and R _z was 5 μm.

Example 3 Five parts of acetylene black were blended with 100 parts of a polyisoprene polyol having a molecular weight of 2500 (OH group = 47.1), and the mixture was stirred for 30 minutes. Then, crude MDI (NCO% = 31.7) was added to 13.3.
3 parts, 0.001 part of dibutyltin dilaurate,
Stirred for minutes. Next, a shaft is arranged, and the reaction mixture is poured into a mold preheated to 90 ° C.
A curing reaction was performed at 12 ° C. for 12 hours to obtain a roller. By polishing the surface of the roller to prepare a first coating layer having an average roughness 7μmR _z. Volume resistivity by sheet sample is 7 × 10
It was ³ Ωcm.

Next, the above roller was coated with MEK soluble copolymer polycarbonate (2 × 10 ¹³ Ωcm, manufactured by Idemitsu Kosan Co., Ltd.).
A second coating layer of about 5 μm was formed using a weight% MEK solution. At this time, the roller resistance was 2 × 10 ⁷ Ω, and R _z was 5 μm.

Example 4 5% by weight of a solvent-soluble fluororesin (Velflon 1000, volume resistivity 2 × 10 ¹³ Ωcm, manufactured by NOF Corporation) instead of copolymerized polycarbonate
A roller was prepared in the same manner as in Example 3, except that a second coating layer of about 5 μm was formed using a toluene solution. At this time, the roller resistance was 5 × 10 ⁷ Ω, and Rz was 5 μm.

(Example 5) 100 parts of EPDM (EP33, manufactured by Nippon Synthetic Rubber Co., Ltd.) was added to ISAF carbon 2
5 parts, 5 parts of zinc white, 1 part of stearic acid and 1 part of dicumyl peroxide were mixed by a roll mill, the mixture was wound around the outer periphery of a metal shaft, and 100 kg / cm ² in a mold preheated to 150 ° C. The roller having the structure shown in FIG. 1 was obtained by molding for 30 minutes under the pressure described above, and its surface was polished to a JIS 10-point average roughness of 7 μm. The volume resistivity of the sheet sample was 2 × 10 ⁴ Ωcm. Next, a second coating layer of about 5 μm was formed in the same manner as in Example 2 using the above roller. At this time, the roller resistance is 5 × 10
^{7 Ω,} R _z was 5 [mu] m.

Comparative Example 1 A first coating layer was prepared in the same manner as in Example 1 except that acetylene black was used as one part, and used as an evaluation sample. The volume resistivity of the sheet sample prepared at the same time was 7 × 10 ⁷ Ωcm.

Comparative Example 2 10 parts of carbon black (manufactured by Printex 95, Degussa) were added to 90 parts of a solution of 10% by weight of soluble nylon in methanol used in Example 1 and mixed with Red Devil. Thus, a dispersion was obtained. The roll prepared in Comparative Example 1 was immersed in the dispersion and dried to form a second coating layer of about 6 μm. At this time, the roll resistance was 5 × 10 ⁷ Ω, and R _z was 5 μm. The volume resistivity of only the second coating layer is 5 × 10 ⁷ Ω.
cm.

(Comparative Example 3) The roller having only the first coating layer prepared in Example 1 was immersed in a solution in which 20% by weight of soluble nylon was dissolved in methanol, pulled up and dried, and dried to about 26 μm. A second coating layer was formed. At this time, the roller resistance was 2 × 10 ⁸ Ω and R _z was 2 μm.

(Comparative Example 4) The roller having only the first coating layer prepared in Example 1 was immersed in a solution in which 10% by weight of an acrylic resin (Hitaroid 3001, manufactured by Hitachi Chemical Co., Ltd.) was dissolved in MEK. To form a second coating layer of about 5 μm. At this time, R _z was 5 μm. Roller resistance could not be measured because cracks occurred during compression.

The rolls obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were subjected to the following characteristic tests. (1) Contamination of photosensitive drum Each roller is made of NEC, Printer PC-PR1000E /
4 and pressed against the photosensitive drum at a load of 500 g at both ends.
The mixture was allowed to stand at 85 ° C. and 85% RH for 5 hours, and the surface of the photosensitive drum was contaminated, and the actual image was visually observed. (2) Amount of toner charge Each roller is mounted on the developing unit shown in FIG. 2 as a developing roller and rotated at a peripheral speed of 50 mm / sec to form a uniform thin toner layer on the surface of the developing roller. The layer was sucked with air and introduced into a Faraday gauge, and the charge amount was measured. (3) Surface lubrication Each roller is manufactured by Shinto Kagaku's surface measurement device HEIDON-14.
The sample was fixed to the sample stage D, and the frictional force was measured using a SUS plate at a load of 50 g and a speed of 100 mm / min. Comparative Example 1
The frictional force of each roller was set to 1, and the relative value was regarded as the surface smoothness of each roller. (4) Image output Using the developing unit shown in FIG. 2 with each roller as a developing roller, using a non-magnetic one-component toner having an average particle diameter of 7 μm, image is output by reversal development while rotating at a linear speed of 60 mm / sec. The initial solid black, halftone density unevenness, character sharpness (character thickening), fog, occurrence of dust, etc. were evaluated. (5) Roller Wear The roller diameter after 60 hours of rotation was measured by a laser outer diameter measuring machine LMS3000 (manufactured by Mitutoyo Corporation) using the same developing device. The difference between the roller diameters before and after the test was defined as the roller wear amount. Table 1 shows the results.

[0045]

[Table 1]

[0046]

According to the present invention, it is possible to obtain not only a high-quality image having low hardness and good adhesion, but also low contamination and no fog or density unevenness without contaminating a photoreceptor or the like. In addition, it is possible to provide a developer carrying member (developing member) and an electrophotographic apparatus using the developer carrying member, which do not cause variations in performance even in manufacturing.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view of an electrophotographic apparatus showing an example of the present invention.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takahiro Kawagoe 1302-57 Aobadai, Tokorozawa-shi, Saitama (56) References JP-A-64-66674 (JP, A) JP-A-5-107874 (JP, A) JP-A-5-281831 (JP, A) JP-A-2-294675 (JP, A) JP-A-4-208960 (JP, A) JP-A-4-24670 (JP, A) JP-A-4-208961 ( JP, A) JP-A-4-134468 (JP, A) JP-A-6-186838 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/02 G03G 15/08 501 D G03G 15/09 A G03G 15/16 103

Claims (4)

(57) [Claims] A developer is carried on the surface to form a thin film of the developer, and in this state, the developer contacts the latent image holding member holding the electrostatic latent image on the surface to transfer the developer from the thin film. A developer carrying member for adhering to the surface of the image carrier to visualize the electrostatic latent image, comprising: a first coating layer made of an elastic body having a volume resistivity ρ1 of 10 ⁷ Ωcm or less; and a first coating layer formed on the first coating layer. And the volume resistivity ρ
2 having a second coating layer satisfying ρ2 / ρ1 ≧ 1000, and the first coating layer has a surface roughness R of 3 to 15 in JIS 10 point roughness Rz.
a developer carrying member satisfying a condition of 0.1 <d <3 × R when the thickness of the second coating layer is d. 2. The method according to claim 1, wherein the second coating layer is mainly composed of any one selected from a soluble nylon containing no conductive powder, a urethane-modified acrylic resin, a modified polycarbonate, and a fluororesin. Developer carrying member. 3. The developer-carrying member according to claim 1, wherein the first coating layer is based on a polyurethane elastomer or EPDM. 4. The developer carrying member according to claim 1, wherein the developer is carried on a surface of the developer carrying member to form a thin film of the developer. A developing device for contacting the latent image holding member holding the electrostatic latent image on the surface thereof and adhering the developer from the thin film to the surface of the latent image holding member to visualize the electrostatic latent image; Electrophotographic apparatus.