JP3159156B2 - Developing roller and developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing roller for visualizing an electrostatic latent image with a non-magnetic one-component developer in an electrophotographic apparatus such as a copying machine or a printer, or an electrostatic recording apparatus. More specifically, the present invention relates to a developing roller having excellent stain resistance and capable of reliably obtaining a good image even in long-term use, and a developing device using the 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 non-magnetic one-component developer is supplied to a photosensitive member holding a latent image and the latent image on the photosensitive member is supplied to the photosensitive member. As a developing method for visualizing a latent image by attaching a developer, a pressure developing method is known (US Pat. No. 3,515,2012).
According to this method, since a magnetic material is not required, the apparatus can be simplified and downsized easily, 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 developing method, as shown in FIG. 2, for example, a toner applying roller 4 for supplying toner and a photoconductor 5 holding an electrostatic latent image
The developing roller 1 is disposed in contact with the photoconductor 5 and slightly separated from the toner coating roller 4. The developing roller 1, the photoconductor 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 arranged in a uniform thin layer by the layering blade 7, and the developing roller 1 contacts the photoconductor 5 in this state. By rotating while rotating, the toner formed in a thin layer adheres to the latent image on the photoconductor 5 from the developing roller 1 and the latent image is 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 a surface of the photoreceptor 5 after transfer by a cleaning blade 10. The remaining toner is removed.

In this case, the developing roller 1 must rotate while reliably maintaining a state in which the developing roller 1 is in close contact with the photosensitive member 5.
For this reason, as shown in FIG. 1, silicone rubber, NB
It has a structure in which a conductive agent is blended into an elastic rubber such as R or EPDM or urethane foam to form an elastic layer 3 made of an elastic body having 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 or NBR, if the hardness is lowered to obtain good adhesion, contamination of the photoconductor may occur. 2. When the elastic layer is formed from a sponge body such as urethane foam, if the toner enters the elastic layer and is used for a long period of time, the roller may become hard due to toner clogging, or toner charging failure may occur, resulting in poor image quality. May decrease.

Further, a developing roller composed of a single elastic layer generally has insufficient charging rise characteristics of toner on the roller, and causes problems such as poor cleaning due to fogging selective development due to poor charging of toner and a decrease in print density. Easy,
The 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, has low hardness and good adhesion, does not cause inconvenience such as contaminating a photoreceptor, etc., and has no unevenness in density or background fog. An object of the present invention is to provide a developing roller capable of obtaining a high-quality image and not causing deterioration in image quality even when used for a long period of time, and a developing device using the developing roller.

[0009]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, have formed an elastic layer having conductivity on the outer periphery of a good conductive shaft. In the developing roller, the elastic layer may be used as an isocyanate and modified diphenylmethane-4,4′-
Diisocyanate or crude diphenylmethane-4,4 '
-A single-layered elastic layer formed by adding carbon black having a pH of 5 or more to a urethane elastomer obtained using a diisocyanate, and in particular, the low efficiency of the urethane elastomer forming an elastic layer is 10 ⁴ to 10 ¹⁰ Ωcm,
Hardness is 55 ° or less on JIS-A scale, and surface roughness is J
By adjusting below 10μmRz in IS10-point average roughness, negatively charges the same time to form a thin layer of the developer carrying a non-magnetic one-component developer on the developing roller surface, which photosensitive member When the electrostatic latent image on the latent image holding member is developed by contacting the latent image holding member with the developing device, the developing roller may be brought into good contact with the latent image holding member, and the latent image holding member may be contaminated. A high-quality image without unevenness of density or background fogging can be obtained without causing unevenness, and the image quality does not deteriorate even after long-term use. It has been found that by forming the elastic layer of the roller, the above-mentioned excellent performance can be surely exerted even in a high-temperature and high-humidity environment, and the present invention has been completed.

Accordingly, the present invention provides an electroconductive elastic layer formed on the outer periphery of a highly conductive shaft, and a nonmagnetic one-component developer carried on the surface of the elastic layer to form a thin layer of the developer. While forming, the non-magnetic one-component developer is negatively charged, and in this state, the developer contacts the latent image holding member holding the electrostatic latent image on the surface, and transfers the developer from the thin layer to the surface of the latent image holding member. A developing roller for adhering to the electrostatic latent image and visualizing the electrostatic latent image, wherein the elastic layer is a single-layered elastic layer made of a urethane elastomer containing carbon black having a pH of 5 or more; Is a modified diphenylmethane-4,4′-
Diisocyanate or crude diphenylmethane-4,4 '
-To provide a developing roller, which does not substantially contaminate the latent image holding member obtained by using diisocyanate.

In this case, according to a preferred embodiment, the urethane elastomer forming the elastic layer has a resistivity of 10 ⁴ to 10 ¹⁰ Ωcm, a hardness of 55 ° or less on a JIS-A scale, and a surface roughness of JIS 10 points average roughness 10μ
Provided are a developing roller having an mRz or less and a developing roller in which a urethane elastomer for forming an elastic layer contains silicone powder.

Further, the present invention provides a roller- or drum-shaped latent image holding member for holding an electrostatic latent image on a surface thereof, and a latent image holding member provided with a non-magnetic one-component developer on an outer peripheral surface thereof. The non-magnetic one-component developer is adhered to the electrostatic latent image on the surface of the latent image holding member by rotating the surface of the latent image holding member in contact with the surface of the latent image holding member. A developing device comprising a developing roller for visualization, wherein the developing roller according to the present invention is used as the developing roller.

Hereinafter, the present invention will be described in more detail.
As shown in FIG. 1, the developing roller of the present invention is formed by forming a conductive elastic layer 3 on the outer periphery of a good conductive shaft 2.

As the shaft 2, any shaft having good conductivity can be used, but usually a metal core made of a solid metal body or the inside is 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 has a single-layer structure made of a urethane elastomer containing carbon black having a pH of 5 or more. In this case, the urethane elastomer is used as an isocyanate. What is necessary is just to use the specific isocyanate, and the manufacturing method may be any. For example, a method in which carbon black is blended in a polyurethane prepolymer and the prepolymer is crosslinked and cured. A conductive material can be blended with a polyol, 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. Further, thermoplastic urethane may be used.

The polyol used in the present invention is not particularly limited, and examples thereof include a polyether polyol, a polyester polyol, a polyolefin polyol, and a mixture thereof. Examples of such polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. Examples of polyester polyols include aliphatic glycols such as ethylene glycol, propylene glycol, butylene glycol, pentene glycol, and hexene glycol; glycols such as polyalkylene glycols such as diethylene glycol and dipropylene glycol; and trimethylolpropane. Polyhydric alcohols having three or more functional groups are used as alcohol components, and these are used in the form of aliphatic dicarboxylic acids such as adipic acid, sebacic acid, suberic acid, brassic acid, and succinic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid. Examples thereof include condensed polyester polyols obtained as a basic acid component. Examples of the polyolefin polyol include polybutadiene polyol and polyisoprene polyol.

In the present invention, uretonimine-modified diphenylmethane-4,
Modified diphenylmethane-4,4'-diisocyanate such as 4'-diisocyanate, urethane-modified diphenylmethane-4,4'-diisocyanate, or crude diphenylmethane-4,4'-diisocyanate is used. Use of these isocyanates Thus, contamination of the photoreceptor can be reduced.

In the developing roller of the present invention, the urethane elastomer is blended with carbon black to impart conductivity, and the conductive urethane elastomer is used to form the elastic layer 3.
, And in this case, carbon black having a pH of 5 or more was used. That is, it is known that the triboelectrification characteristics of carbon black become positive as the pH value increases and conversely become negative as the pH decreases. In this case, the developing roller of the present invention has a non-magnetic property. The carbon black has a pH of 5 or more to negatively charge the toner of the one-component developer.
In fact, when using a non-magnetic one-component negatively chargeable toner,
On the roller containing carbon black having a value of less than 5, the amount of the toner of the opposite polarity increased and toner dust was observed.

As long as the carbon black used in the developing roller of the present invention has a pH of 5 or more, any of acetylene black, Ketjen black, furnace black and the like can be used. Furnace black having a pH of 6 or more is particularly preferable. used.

Here, the pH of carbon black varies depending on the number of functional groups, particularly carboxyl groups, etc. on the surface of carbon black, and serves as an index for knowing acidity and basicity. That is, generally, the surface of carbon black contains oxygen-containing functional groups such as phenolic hydroxyl groups, carboxyl groups, and quinone-type oxygen, and the number of these surface functional groups differs depending on the type of carbon black. In this case, the surface properties of the carbon black mainly differ depending on the production method, and there are many functional groups on the surface of the channel black, but few on the surfaces of the furnace black and the acetylene black. For the pH of the carbon black, for example, about 5 g of a sample is boiled in 150 cc of distilled water for 5 minutes, left to cool to room temperature, and centrifuged (2,000 RPM) for 3 minutes in a centrifuge. The sludge can be separated by removing the supernatant, put into a beaker as a measurement sample, and measure the pH with a pH meter to determine the sludge.

The elastic layer 3 thus obtained is
Although not subject to any particular limitation, it is preferable that the resistance of the carbon black be 10 ⁴ to 10 ¹⁰ Ωcm, particularly 10 ⁶ to 10 ⁹ Ωcm, depending on the composition of the carbon black. If the resistance value is less than 10 ⁴ Ωcm, electric charges may leak to the photosensitive drum or the like, or the developing roller itself may be broken by a voltage. On the other hand, if the resistance value exceeds 10 ¹⁰ Ωcm, fogging tends to occur. In this case, the resistance value may be adjusted by using other conductive additives such as metal powder and metal oxide together with the carbon black. The mixing ratio of the carbon black to the urethane elastomer is not particularly limited, and is generally in a range where the resistance value of the elastic layer can be adjusted to the above range. Specifically, 100 parts of the urethane elastomer (parts by weight, hereinafter 0.5 to 50 for the same)
Parts, especially 1 to 30 parts. Further, the adjustment of the resistance value may be performed by blending an ionic conductive substance such as sodium perchlorate and tetraethylammonium chloride.

Although the hardness of the elastic layer 3 is not particularly limited, it is not more than 55 ° on the JIS-A scale, especially 25 °.
It is preferable to set it to 45 °. In this case, the hardness is 55
Exceeding ° may result in a small contact area with the photosensitive drum or the like, making it impossible to perform good development.However, 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 a low hardness, it is preferable to reduce the compression set as much as possible, specifically, it is preferable to set it to 20% or less.

The surface roughness of the elastic layer 3, that is, the surface roughness of the developing roller of the present invention is not particularly limited, but the JIS 10-point average roughness is 10 μmRz or less, particularly 1 μmRz.
８8 μmRz is preferred. Surface roughness 10μ
If it exceeds mRz, the thickness of the toner layer of the non-magnetic one-component developer (toner) and the uniformity of charging may be impaired.
By adjusting the thickness to 10 μmRz or less, the adhesion of the toner can be improved, and the deterioration of the image due to the wear of the roller during long-term use can be more reliably prevented.

In the developing roller of the present invention, the elastic layer 3 is formed of the urethane elastomer containing the specific isocyanate and carbon black having a pH of 5 or more. Preferably, the elastic layer 3 made of the urethane elastomer has a resistance value of: Although the hardness and the surface roughness are adjusted as described above, the elastic layer 3 can be formed by further adding a silicone powder to the urethane elastomer, whereby the performance degradation under a high temperature and high humidity environment is prevented. It is possible to effectively prevent the occurrence of fog, particularly in a high-temperature and high-humidity environment.

That is, since the urethane elastomer generally has high hygroscopicity, the toner charging ability on the roller surface is reduced under high temperature and high humidity. This leads to an increase in the amount of weakly charged toner in the toner layer on the roller surface, causing fogging. On the other hand, silicone powder is excellent in water repellency and by dispersing it in urethane elastomer,
In particular, it is possible to suppress the hygroscopicity of the roller surface.
Therefore, by adding the silicone powder to the urethane elastomer to form the elastic layer of the roller, it is possible to prevent the toner charging property from deteriorating under high temperature and high humidity without contaminating the latent image holding member, and to realize clear and fog-free. Images can be reliably obtained even under high temperature and high humidity.

The silicone powder may be any of fine particles of silicone resin, fine particles of silicone rubber, and particles of silicone oil supported on an inorganic carrier. Particles having a particle size of 0.1 to 20 μm, more preferably 0.5 to 5 μm, are preferably used. In this case, if the particle size of the silicone powder exceeds 20 μm, the smoothness of the roller surface becomes non-uniform, and the chargeability of the toner becomes non-uniform, which may cause deterioration in image quality. The amount of the silicone powder is not particularly limited, but is usually about 0.1 to 30 parts, and especially about 1 to 1 part, per 100 parts of the urethane elastomer.
It is desirable to use about 0 parts. Further, various charge control agents can be added for the purpose of controlling the toner charge amount on the roller surface using the urethane elastomer. The added charge control agent is a dye or pigment used for controlling toner charge, and examples thereof include nigrosine, triaminotriphenylmethane, dye, cationic dye, dioxazine, azo pigment, azochrome complex, and quinacridone. Can be The amount of these charge control agents is usually 0.1 to 20 with respect to 100 parts of the urethane elastomer.
Parts, especially about 1 to 5 parts.

The developing roller of the present invention can be incorporated in a normal developing device using a non-magnetic monodisperse developer. Specifically, as shown in FIG. 2, a toner applying roller for supplying toner The developing roller 1 of the present invention is disposed between the photosensitive drum 5 and the photosensitive drum 5 holding the electrostatic latent image in a state where the developing roller 1 is in contact with the photosensitive drum 5, and the toner applying roller 4 supplies the toner 6 to the developing roller 1. 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. Can be. Note that FIG.
Is described in the prior art, and the description is omitted.

[0028]

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. [Example 1] Polyether polyol having a molecular weight of 5,000 by adding propylene oxide and ethylene oxide to glycerin (Exenol 8 manufactured by Asahi Glass Co., Ltd.)
28) (OH value 33) 100 parts (parts by weight, the same applies hereinafter)
1.0 part of 1,4-butanediol, 1.5 parts of a silicon surfactant (manufactured by Nippon Unica, L-520), 0.5 part of nickel acetylacetonate, 0.01 part of dibutyltin dilaurate and acetylene 1.0 part of black (manufactured by Denka, pH 6.9) was added, and the mixture was preliminarily mixed using a mixer, and then kneaded with a paint roll to uniformly disperse acetylene black, thereby preparing a polyol composition.

The polyol composition was stirred under reduced pressure to remove bubbles, and then 17.5 parts of urethane-modified MDI (Sumijur PF, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was added, followed by 2 additions.
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 surface of the obtained roller is polished and the surface is JIS10-point average roughness 7 μmR
Adjusted to _z , and used as developing roller A. In addition, 1 part of silicone powder (Toray Silicone Co., Ltd., Trefil E-500, particle size: 3 μm) was added to the above polyol composition, and a developing roller B was manufactured in the same manner.

Example 2 A developing roller A (silicone powder-free) was prepared in the same manner as in Example 1 except that 1,4-butanediol was not added and the amount of Sumidur PF was changed to 12.5 parts. Compound B) and B (silicone powder compound).

Example 3 3.32 parts of acetylene black was blended with 100 parts of a polyisoprene polyol having a molecular weight of 2500 (OH group = 47.1) and stirred for 30 minutes.
After that, Crude MDI (NCO% = 31.7)
3.33 parts and 0.001 part of dibutyltin dilaurate were added and stirred for 3 minutes. Next, the shaft is arranged, and 9
This reaction mixture was poured into a mold heated to 0 ° C., and a curing reaction was performed at 90 ° C. for 12 hours to obtain a roller.
The developing roller A was obtained from the obtained roller in the same manner as in Example 1.
(No silicone powder blended) and B (silicone powder blended) were prepared.

Example 4 Uretonimine-modified MDI3
1 modified MDI containing 0% by weight (NCO% = 29.0)
Developing rollers A (without silicone powder) and B (with silicone powder) were prepared in the same manner as in Example 3 except that 3.47 parts were used.

Example 5 Ketjen EC Black (manufactured by Lion Corporation, pH 9.0) instead of acetylene black
Developing roller A (without silicone powder) was produced in the same manner as in Example 1 except that 1 part of was added.

Example 6 A developing roller was prepared in the same manner as in Example 1 except that 1 part of Tospearl 108 (manufactured by Toshiba Silicone Co., particle size 0.8 μm) was added as a silicone powder instead of Trefil E-500. B (compound of silicone powder) was produced.

Example 7 100 parts of Exenol 82
Add 25 parts of Sumidur PF to 8 and add 3 parts at 60 ° C.
After reacting for 1 minute, a prepolymer was obtained. Ketjen EC Black (manufactured by Lion, pH
9.0), and 100 parts of Exenol 828 were further added and stirred and mixed to prepare a polyol composition.
A developing roller A (without silicone powder) was manufactured in the same manner as in Example 1. Further, 1 part of Trefil E-500 was added to the above polyol composition, and a developing roller B (containing silicone powder) was produced in the same manner.

Example 8 A furnace black HAF (manufactured by Mitsubishi Kasei, pH 7.0) was used in place of acetylene black.
Developing rollers A (without silicone powder) and B (with silicone powder) were produced in the same manner as in Example 1 except that 15 parts of 5) were added.

Example 9 A developing roller A (silicone powder) was prepared in the same manner as in Example 1 except that 3 parts of a nigrosine-based charge control agent (BONTRON N-04, manufactured by Orient Chemical Industries) was further added to the polyol composition. (Body unblended) and B (silicone powder blended) were produced.

Example 10 In Example 1, a triaminotriphenylmethane-based charge control agent (Copy Blue PR, manufactured by Hoechst Japan) was used as a charge control agent.
Developing rollers A (without silicone powder) and B (with silicone powder) were produced in the same manner except that 3 parts were added.

Comparative Example 1 A developing roller A (silicone powder) was prepared in the same manner as in Example 1 except that 30 parts of carbon black PRINTEX-U (manufactured by Degussa) was added in place of acetylene black. Compound B) and B (silicone powder compound).

COMPARATIVE EXAMPLE 2 The amount of 1,4-butanediol was 3 parts, the amount of Sumidur PF was 27.5 parts, and 30 parts of PRINTEX-U were added in place of acetylene black. Developing rollers A (without silicone powder) and B (with silicone powder) were produced in the same manner as in Example 1.

Comparative Example 3 In place of acetylene black, natural graphite AOP (manufactured by Nippon Graphite Co., Ltd., pH 6.
Developing rollers A (without silicone powder) and B (with silicone powder) were produced in the same manner as in Example 1 except that 15 parts of 3) was added.

[Comparative Example 4] In place of acetylene black, 30 parts of PRINTEX-U was added, and in the surface polishing step, the surface roughness was 13 μm in terms of JIS 10-point average roughness.
Developing rollers A (without silicone powder) and B (with silicone powder) were manufactured in the same manner as in Example 1, except that the adjustment was made to _Rz .

Comparative Example 5 8.3 of Example 1 was replaced with tolylene diisocyanate instead of urethane-modified MDI.
A developing roller A (without silicone powder) was manufactured in the same manner except that a part was added.

With respect to the developing rollers obtained in Examples 1 to 10 and Comparative Examples 1 to 5, the following characteristic tests were performed. Table 1 shows the results. (1) Electric Resistance A sheet-like sample prepared under the same conditions as each roller was measured using a resistivity meter Hiresta (manufactured by Mitsubishi Yuka Corporation) by applying a voltage of 100 V. (2) Hardness and Compression Permanent A sheet-like sample prepared under the same conditions as each roller was measured according to JIS-K6301 (hardness is A type). (3) Surface roughness For each roller, a surface roughness meter Handy Surf E-30
It was measured using a type A (manufactured by Tokyo Seimitsu Co., Ltd.). (4) Contamination of photosensitive drum Each roller was pressed against a photosensitive drum for printer SP-3 manufactured by Ricoh Co., Ltd. with a load of 500 g, and left at 30 ° C. and 85% RH for 72 hours to visually check the surface of the photosensitive drum for contamination. Confirmed. (5) Toner charge amount 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. (6) Image output Each roller is attached to the developing unit shown in FIG. 2 as a developing roller, and images are output while reversing development and rotating at a linear speed of 60 mm / sec. Was evaluated for fog and toner dust.
At the same time, the state of toner filming on the roller surface after 2,000 prints was also observed.

[0045]

[Table 1] Note) * 1: Roller A contains no silicone powder, Roller B contains silicone powder.
For the condition of H, two-stage writing, the upper stage is 23 ° C,
The lower row shows the results of testing under the conditions of 55% RH, and the lower row shows the results of tests performed at 33 ° C. and 85% RH.

As is evident from the results in Table 1, according to the development of the present invention, a high-quality image free from unevenness of density and background fog can be obtained without inconvenience such as contamination of the photoreceptor. In addition, it was confirmed that the image quality did not deteriorate even after long-term use, and that the addition of the silicone powder could prevent the performance deterioration even under high temperature and high humidity. It was also found that the charge amount of the toner was improved by the addition of the charge control agent.

[0047]

As described above, according to the developing roller of the present invention, it has low hardness and good adhesion, does not cause inconvenience such as contaminating a photoreceptor, etc., and has uneven density and ground. A high-quality image without fogging or the like can be obtained, and the image quality does not deteriorate even after long-term use.

[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 Development 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

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-187732 (JP, A) JP-A-4-256985 (JP, A) JP-A-3-249675 (JP, A) JP-A-4-249 134468 (JP, A) JP-A-4-199156 (JP, A) JP-A-4-204,971 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08-15 / 095 F16C 13/00

Claims (6)

(57) [Claims] An elastic layer having conductivity is formed on an outer periphery of a good conductive shaft, and a non-magnetic one-component developer is carried on the surface of the elastic layer to form a thin layer of the developer.
The non-magnetic one-component developer is negatively charged, and in this state, the developer contacts the latent image holding member holding the electrostatic latent image on the surface, and transfers the developer from the thin layer to the electrostatic latent image on the surface of the latent image holding member. In a developing roller for adhering to an image and visualizing the electrostatic latent image, the elastic layer is a single-layer elastic layer made of a urethane elastomer containing carbon black having a pH of 5 or more, and the urethane elastomer is used as an isocyanate. A developing roller which does not substantially contaminate the latent image holding member obtained by using modified diphenylmethane-4,4'-diisocyanate or crude diphenylmethane-4,4'-diisocyanate. 2. The urethane elastomer forming the elastic layer has a resistivity of 10 ⁴ to 10 ¹⁰ Ωcm and a hardness of JIS-A.
2. The developing roller according to claim 1, wherein the developing roller has a surface roughness of not more than 55 [deg.] And a surface roughness of not more than 10 [mu] mRz in terms of JIS 10 point average roughness. 3. The developing roller according to claim 1, wherein the carbon black is furnace black. 4. The developing roller according to claim 1, wherein the urethane elastomer forming the elastic layer contains a silicone powder. 5. The developing roller according to claim 1, wherein the urethane elastomer forming the elastic layer contains a charge control agent. 6. A roller-shaped or drum-shaped latent image holder for holding an electrostatic latent image on a surface thereof, and a non-magnetic one-component developer supported on an outer peripheral surface of the latent image holder. A developing roller that visualizes the electrostatic latent image by causing the non-magnetic one-component developer to adhere to the electrostatic latent image on the surface of the latent image holding member by rotating in conjunction with the rotational movement of the latent image holding member; A developing device comprising: the developing roller according to claim 1 as the developing roller.