JPH07261542A - Developing roller and developing device - Google Patents

Abstract

PURPOSE:To provide a developing roller having low hardness and good adhesiveness, causing no trouble to pollute a photoreceptor, obtaining a high-quality image having no density irregularity and no backing fog, and having no deterioration of the image quality in use over a long period by forming an elastic layer out of a urethane elastomer containing carbon black with pH of 5 or above. CONSTITUTION:A developing roller 1 is formed with a conducting elastic layer 3 on the outer periphery of a good-conductivity shaft 2, and the elastic layer 3 is made of a urethane elastomer containing carbon black with pH of 5 or above. The urethane elastomer forming the elastic layer 3 has the electrical resistivity of 10<4>-10<10>OMEGA.cm, the hardness of 55 deg. or below at the JIS-A scale, the surface roughness of 10mumR2 or below in the JIS 10-point average roughness due to the combination of carbon black. Furnace black is used for the carbon black, and polyolefin polyol is used as the polyol to obtain the urethane elastomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing roller and 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, it relates to a developing device used, and more particularly to a developing roller which is excellent in stain resistance and can surely obtain 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, an electrostatic recording apparatus, etc., 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 A pressure developing method is known as a developing method for visualizing a latent image by attaching a developer (US Pat. No. 3,152,2012).
No. 3731146, etc.), this method does not require a magnetic material, so that the apparatus can be simplified and downsized, and the toner can be colored easily.

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

That is, in this pressure developing method, as shown in FIG. 2, for example, between the toner coating roller 4 for supplying toner and the photoconductor 5 holding the electrostatic latent image,
The developing roller 1 is arranged in contact with the photoconductor 5 and slightly separated from the toner applying roller 4, and the developing roller 1, the photoconductor 5 and the toner applying roller 4 are respectively arranged in the directions of arrows in the drawing. By rotating, the toner 6 is supplied to the surface of the developing roller 1 by the toner applying roller 4, and this toner is adjusted to a uniform thin layer by the stratifying 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 from the developing roller 1 to the latent image on the photoconductor 5 so that the latent image becomes visible. In the figure, reference numeral 8 is a transfer section, which is adapted to transfer a toner image onto a recording medium such as paper, and 9 is a cleaning section whose cleaning blade 10 transfers the toner image onto the surface of the photoreceptor 5. It is designed to remove the residual toner.

In this case, the developing roller 1 must rotate while securely holding the state in which the developing roller 1 is in close contact with the photoconductor 5.
Therefore, as shown in FIG. 1, silicone rubber, NB, etc. are attached to the outer periphery of the shaft 2 made of a metal or other good conductive material.
It has a structure in which an elastic layer 3 made of an elastic body to which conductivity is imparted is formed by mixing a conductive agent into elastic rubber such as R or EPDM or urethane foam.

[0006]

However, the above-mentioned conventional developing roller has the following drawbacks due to the characteristics of its elastic layer. 1. When the elastic layer is formed of an elastic rubber such as silicone rubber or NBR, the photoreceptor may be contaminated if the hardness is lowered to obtain good adhesion. 2. When the elastic layer is formed from a sponge 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 clogging of the toner, or the toner may be improperly charged, resulting in poor image quality. May decrease.

[0007] Generally, a developing roller composed of a single elastic layer does not have sufficient charge rise characteristics of toner on the roller, and problems such as poor cleaning due to fog selective development due to poor charging of toner and reduction in print density occur. Easy,
The printing quality is significantly deteriorated by long-term continuous printing. This phenomenon is particularly remarkable in 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 photosensitive member, and has no uneven density or background fog. An object of the present invention is to provide a developing roller that can obtain a high-quality image and that does not cause deterioration in image quality even after long-term use, and a developing device using the developing roller.

[0009]

Means for Solving the Problems The present inventor has conducted diligent studies to achieve the above-mentioned object, and as a result, in a developing roller having a conductive elastic layer formed on the outer periphery of a good conductive shaft. The elastic layer is formed of a urethane elastomer containing carbon black having a pH of 5 or more,
In particular, its resistivity is 10 ⁴ to 10 ¹⁰ Ωcm, and its hardness is JIS
By adjusting the surface roughness to 55 ° or less on the A scale and to 10 μmR _z or less in accordance with JIS 10-point average roughness, a nonmagnetic one-component developer is carried on the surface of the developing roller to form a thin layer of the developer. Then, by bringing this into contact with a latent image carrier such as a photoconductor to develop the electrostatic latent image on the latent image carrier,
The developing roller adheres well to the latent image carrier, and without causing the inconvenience of contaminating the latent image carrier, high-quality images without density unevenness or background fog can be obtained, and in long-term use. Does not cause deterioration of image quality,
Further, they have found that the above-mentioned excellent performance can be reliably exhibited even in a high temperature and high humidity environment by blending silicone powder with such urethane elastomer to form the elastic layer of the roller, and completed the present invention. It has come to do.

Therefore, according to the present invention, a conductive elastic layer is formed on the outer periphery of a shaft having good conductivity, and a nonmagnetic one-component developer is carried on the surface of the elastic layer to form a thin layer of the developer. In this state, the electrostatic latent image is held in contact with the latent image holding member on the surface thereof to adhere the developer from the thin layer to the electrostatic latent image on the surface of the latent image holding member. A developing roller for visualizing an image, wherein the elastic layer is made of a urethane elastomer containing carbon black having a pH of 5 or more.

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

Further, according to the present invention, a roller-shaped or drum-shaped latent image holding member for holding an electrostatic latent image on the surface and a latent image holding member for carrying a non-magnetic one-component developer on the outer peripheral surface are carried. The non-magnetic one-component developer is attached to the electrostatic latent image on the surface of the latent image holding member by contacting the surface and rotating in association with the rotational movement of the latent image holding member to form the electrostatic latent image. A developing device comprising a developing roller for visualization, wherein the developing roller of the present invention is used as the developing roller.

The present invention will be described in more detail below.
In the developing roller of the present invention, as shown in FIG. 1, an elastic layer 3 having conductivity is formed on the outer circumference of a good conductive shaft 2.

Here, as the shaft 2, any one can be used as long as it has good conductivity, but usually, a cored bar made of a metallic solid 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 is made of a urethane elastomer containing carbon black having a pH of 5 or more. In this case, this urethane elastomer is manufactured by various methods. For example, a method of blending carbon black into a polyurethane prepolymer and crosslinking and curing the prepolymer, a method of blending a conductive material with a polyol, and reacting the polyol with a polyisocyanate by a one-shot method, etc. Can be obtained at Further, it may be thermoplastic urethane.

The polyol used in the present invention may be a mixture of polyether polyol, polyester polyol and polyolefin polyol. 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, for example. A trifunctional or higher polyhydric alcohol is used as an alcohol component, and these are mixed with an aliphatic dicarboxylic acid such as adipic acid, sebacic acid, suberic acid, brassic acid, succinic acid, or an aromatic dicarboxylic acid such as terephthalic acid or isophthalic acid. Examples thereof include a condensation type polyester polyol obtained as a basic acid component. Examples of the polyolefin polyol include polybutadiene polyol and polyisoprene polyol.

The polyisocyanate is not particularly limited, but polyisocyanate having a bent molecular structure is preferably used, and polyisocyanate represented by the following general formula (1) is particularly preferably used. . Such a polyisocyanate hinders the crystallization of the polyurethane chain, so that it is easy to reduce the hardness, and moreover, the entanglement of the molecular chains is easily formed and the so-called pseudo-crosslinked structure is provided, so that the mold release is also easy.

[0018]

[Chemical 1] (In the formula, R represents a carbon-carbon bond or an alkylene group, and R ′ represents hydrogen or an alkyl group.)

Specific examples of such polyisocyanate include 2,4-toluene diisocyanate and 2,6-
Toluene diisocyanate, a mixture thereof, m-tetramethylxylylene diisocyanate, m-xylene diisocyanate, m-phenylene diisocyanate, diphenylmethane-4,4′-diisocyanate and the like can be mentioned. Of these, diphenylmethane-4,4'-diisocyanate is particularly preferred. In particular, modified diphenylmethane-4,4'-diisocyanate containing uretonimine modified diphenylmethane-4,4'-diisocyanate is preferable from the viewpoint of reduction of photoreceptor contamination. In addition,
The content ratio is preferably 5 to 50% by weight. Also, crude diphenylmethane-4,4'-diisocyanate is preferably used.

In the developing roller of the present invention, carbon black is mixed with the urethane elastomer to impart conductivity, and the elastic layer 3 is made of the conductive urethane elastomer.
In this case, carbon black having a pH of 5 or higher is 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 is nonmagnetic. The pH of the carbon black is set to 5 or more in order to negatively charge the toner of the one-component developer.
In fact, when using non-magnetic one-component negative charging toner,
On the roller containing carbon black having a value of less than 5, reverse polarity toner was increased and toner dust was observed.

As the carbon black used in the developing roller of the present invention, any of acetylene black, Ketjen black, furnace black and the like can be used as long as it has a pH of 5 or more, but 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 on the surface of carbon black, particularly carboxyl groups, and is an index for knowing acidity and basicity. That is, in general, oxygen-containing functional groups such as phenolic hydroxyl groups, carboxyl groups, and quinone-type oxygen are present on the surface of carbon black, and the number of surface functional groups varies depending on the type of carbon black. In this case, the surface properties of carbon black differ mainly depending on the production method, and the surface of the channel black has many functional groups, whereas the surface of the furnace black or acetylene black has few functional groups. The pH of this carbon black is, for example, about 5 g of a sample is boiled in 150 cc of distilled water for 5 minutes, left to stand, cooled to room temperature, and centrifuged for 3 minutes (2,000 RPM) in a centrifuge. It can be determined by removing the supernatant and separating the sludge, placing it in a beaker as a measurement sample, and measuring the pH with a pH meter.

The elastic layer 3 thus obtained is
Although not particularly limited, it is preferable to adjust the resistance value to 10 ⁴ to 10 ¹⁰ Ωcm, particularly 10 ⁶ to 10 ⁹ Ωcm by blending 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 destroyed by the voltage. On the other hand, if the resistance value exceeds 10 ¹⁰ Ωcm, background fog is likely 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 blending ratio of carbon black with respect to the urethane elastomer is not particularly limited and is usually within a range in which the resistance value of the elastic layer can be adjusted to the above range. Specifically, 100 parts by weight of the urethane elastomer (parts by weight, hereinafter 0.5-50 for the same)
Parts, in particular 1 to 30 parts. The resistance value may be adjusted by adding an ion conductive substance such as sodium perchlorate or tetraethylammonium chloride.

The hardness of the elastic layer 3 is not particularly limited, but 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
If it exceeds °, the contact area with the photosensitive drum etc. will be small and good development may not be possible, but if the hardness is too low, the compression set becomes large and the developing roller is deformed or eccentric for some reason. In this case, density unevenness of the image will occur. Therefore, even when the hardness of the elastic layer is set to a low hardness, it is preferable that the compression set is as small as possible, and specifically, it is preferably 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 μmR _z or less, particularly 1
It is preferably set to 8 μmR _z . Surface roughness is 10μ
When it exceeds mR _z , the layer thickness of the toner layer of the non-magnetic one-component developer (toner) and the uniformity of charging may be impaired.
When it is 10 μmR _z or less, the adhesion of the toner can be improved, and the image deterioration due to the abrasion of the roller during long-term use can be more reliably prevented.

In the developing roller of the present invention, the elastic layer 3 of the developing roller is p.
The urethane elastomer is formed by blending carbon black of H5 or more, and the elastic layer 3 made of the urethane elastomer is preferably adjusted in resistance value, hardness and surface roughness as described above. Since the elastic layer 3 can be formed by adding silicone powder, it is possible to effectively prevent performance deterioration under high temperature and high humidity environment, and particularly effective for generation of fog under high temperature and high humidity environment. Can be reduced to

That is, since urethane elastomers generally have 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, which causes fog. On the other hand, silicone powder has excellent water repellency, and by dispersing it in urethane elastomer,
In particular, it is possible to suppress moisture absorption on the roller surface. Therefore, by adding the silicone powder to the urethane elastomer to form the elastic layer of the roller, the toner chargeability is prevented from deteriorating under high temperature and high humidity without contaminating the image carrier, and a clear image without fog is obtained. Is surely obtained even under high temperature and high humidity.

The silicone powder may be any one of fine particles of silicone resin, fine particles of silicone rubber, and particles of silicone oil supported on an inorganic carrier. Those having a particle size of 0.1 to 20 μm, more preferably 0.5 to 5 μm according to the legal method are preferably used. In this case, if the particle diameter 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 blending amount of the silicone powder is not particularly limited, but is usually about 0.1 to 30 parts, particularly 1 to 1 with respect to 100 parts of the urethane elastomer.
It is desirable that the amount is about 0. 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 charge control agent added is a dye or pigment used for toner charge control, and examples thereof include nigrosine-based dyes, triaminotriphenylmethane-based dyes, cationic dyes, dioxazines, azo-based pigments, azochrome complexes, and quinacridone. To be The amount of these charge control agents to be compounded is usually 0.1 to 20 with respect to 100 parts of the urethane elastomer.
It is desirable that the amount is about 1 part, especially about 1 to 5 parts.

The developing roller of the present invention can be incorporated in an ordinary developing device using a non-magnetic monochromatic developer. Specifically, as shown in FIG. 2, a toner applying roller for supplying toner. 4 and the photosensitive drum 5 holding the electrostatic latent image, the developing roller 1 of the present invention is disposed in contact with the photosensitive drum 5, and the toner 6 is supplied to the developing roller 1 by the toner applying roller 4. Then, this is made into a uniform thin layer by the layering blade 7, toner is further supplied from this thin layer to the photosensitive drum 5, and toner is attached to the electrostatic latent image of the photosensitive drum 5 to visualize the latent image. You can Note that FIG.
Since details of the above have been described in the related art, the description thereof will be omitted.

[0030]

The present invention will be specifically described 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 5000 by adding propylene oxide and ethylene oxide to glycerin (Exenol 8 manufactured by Asahi Glass Co., Ltd.)
28) (OH number 33) 100 parts (weight part, the same applies hereinafter)
In addition, 1.0 part of 1,4-butanediol, 1.5 parts of a silicon surfactant (L-520 manufactured by Nippon Unica Co., Ltd.), 0.5 part of nickel acetylacetonate, 0.01 part of dibutyltin dilaurate and acetylene. 1.0 part of black (manufactured by DENKA CORPORATION, pH 6.9) was added, and premixed using a mixer, and then kneaded with a paint roll to uniformly disperse acetylene black to prepare a polyol composition.

After degassing by stirring this polyol composition under reduced pressure, 17.5 parts of urethane-modified MDI (Sumijour PF manufactured by Sumitomo Bayer Urethane Co., Ltd.) was added to obtain 2
Stir for 1 minute and then cast into a mold heated to 110 ° C,
After curing for 2 hours, an elastic layer was formed on the outer circumference of the metallic shaft to obtain a roller having the structure shown in FIG. The surface of the obtained roller is ground to a JIS 10-point average roughness of 7 μmR.
_The developing roller A was adjusted to _z . Further, 1 part of a 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.

[Embodiment 2] A developing roller A (silicone powder was not added) was prepared in the same manner as in Embodiment 1 except that 1,4-butanediol was not added and the addition amount of Sumidule PF was 12.5 parts. Formulation) and B (silicone powder formulation) were produced.

Example 3 3.32 parts of acetylene black was mixed with 100 parts of polyisoprene polyol having a molecular weight of 2500 (OH group = 47.1), and the mixture was stirred for 30 minutes.
After that, the crude MDI (NCO% = 31.7) is set to 1.
3.33 parts and 0.001 part of dibutyltin dilaurate were added and stirred for 3 minutes. Next, place the shaft, and
The 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 is obtained from the obtained roller in the same manner as in Example 1.
(Silicone powder not blended) and B (Silicone powder blended) were prepared.

[Example 4] Uretonimine modified MDI3
1% of modified MDI containing 0% by weight (NCO% = 29.0)
Developing rollers A (no silicone powder blended) and B (silicone powder blended) 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) was used in place of acetylene black.
A developing roller A (without silicone powder) was manufactured in the same manner as in Example 1 except that 1 part 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., Ltd., particle size: 0.8 μm) was added instead of Trefil E-500 as a silicone powder. B (silicone powder blend) was manufactured.

[Example 7] 100 parts of Exenol 82
Add 8 parts of Sumidule PF to 8 and add 3 at 60 ° C.
The reaction was carried out for a minute to obtain a prepolymer. Ketjen EC black (Lion Co., pH
9.0 parts) and 100 parts of Exenol 828 are further added, and the mixture is stirred and mixed to prepare a polyol composition.
A developing roller A (containing no 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 (blended with silicone powder) was manufactured in the same manner.

[Example 8] Furnace black HAF (manufactured by Mitsubishi Kasei Co., pH 7.
Developing rollers A (without silicone powder blended) and B (with silicone powder blended) were manufactured 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 type charge control agent (BONTRON N-04, manufactured by Orient Chemical Industry Co., Ltd.) was further added to the polyol composition. Body unblended) and B (blended with silicone powder) were produced.

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

[Comparative Example 1] A developing roller A (silicone powder was not used) was used in the same manner as in Example 1 except that 30 parts of carbon black PRINTEX-U (manufactured by Degussa) having a pH of 4.0 was added instead of acetylene black. Formulation) and B (silicone powder formulation) were produced.

[Comparative Example 2] The addition amount of 1,4-butanediol was 3 parts, the addition amount of Sumidule PF was 27.5 parts, and 30 parts of PRINTEX-U was added instead of acetylene black. In the same manner as in Example 1, developing rollers A (no silicone powder blended) and B (silicone powder blended) were manufactured.

COMPARATIVE EXAMPLE 3 Instead of acetylene black, natural graphite AOP (manufactured by Nippon Graphite Co., pH 6.
Developing rollers A (without silicone powder) and B (with silicone powder) were manufactured in the same manner as in Example 1 except that 15 parts of 3) were 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 R _z was adjusted.

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

The following characteristic tests were conducted on the developing rollers obtained in Examples 1 to 10 and Comparative Examples 1 to 5 above. The results are shown in Table 1. (1) Electric resistance A sheet-shaped sample prepared under the same conditions as each roller was measured by applying a voltage of 100 V using a resistivity meter Hiresta (manufactured by Mitsubishi Petrochemical Co., Ltd.). (2) Hardness and compression set A sheet-shaped sample prepared under the same conditions as each roller was measured according to JIS-K6301 (A type for hardness). (3) Surface roughness Handysurf E-30 surface roughness meter for each roller
It was measured using A type (manufactured by Tokyo Seimitsu Co., Ltd.). (4) Contamination of photosensitive drum Each roller is 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 confirm the contamination of the surface of the photosensitive drum. I confirmed it. (5) Toner charge amount Each roller is installed as a developing roller in the developing unit section shown in FIG. 2 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 as a developing roller to the developing unit shown in FIG. 2, and image output is performed while reversing development and rotating at a peripheral speed of 60 mm / sec. The occurrence of fog and toner dust was evaluated.
At the same time, the toner filming state on the roller surface after 2000 printing was also observed.

[0047]

[Table 1] Note) * 1: Roller A is not blended with silicone powder, Roller B is blended with silicone powder. * 2: 3: 1 step: 23 ° C, 55% R
For the H condition and the two-step writing, the upper level is 23 ° C,
The test results were obtained under the conditions of 55% RH and the lower row at 33 ° C. and 85% RH.

As is clear from the results shown in Table 1, according to the development of the present invention, a high-quality image having no density unevenness or background fog is obtained without inconvenience such as contaminating the photosensitive member. Moreover, it was confirmed that the image quality does not deteriorate even after long-term use, and that the addition of the silicone powder can prevent the deterioration of the performance even under high temperature and high humidity. It was also confirmed that the addition of the charge control agent improves the toner charge amount.

[0049]

As described above, according to the developing roller of the present invention, the developing roller has a low hardness and a good adhesiveness, does not cause the inconvenience of contaminating the photoconductor, etc., and has the uneven density and the background. A high-quality image without fog can be obtained, and the image quality does not deteriorate even after long-term use.

[Brief description of drawings]

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

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

[Explanation of symbols]

 1 Developing Roller 2 Shaft 3 Elastic Body 4 Toner Application Roller 5 Photosensitive Drum (Latent Image Holding Body) 6 Toner (Non-Magnetic One-Component Developer) 7 Layering Blade 8 Transfer Section 9 Cleaning Section 10 Cleaning Blade

Claims (9)

[Claims] 1. An elastic layer having conductivity is formed on the 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. In this state, the electrostatic latent image is held in contact with the latent image holding member, and the developer is adhered to the electrostatic latent image on the surface of the latent image holding member from the thin layer to visualize the electrostatic latent image. In the developing roller,
A developing roller, wherein the elastic layer is made of urethane elastomer containing carbon black having a pH of 5 or more. 2. The urethane elastomer forming the elastic layer has a resistivity of 10 ⁴ to 10 ¹⁰ Ωcm and a hardness of JIS-A.
The developing roller according to claim 1, wherein the developing roller has a scale of 55 ° or less and a surface roughness of JIS 10-point average roughness of 10 μmR _z or less. 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 is obtained by using polyolefin polyol as the polyol. 5. A urethane elastomer comprising uretonimine-modified diphenylmethane-4 as an isocyanate,
Modified diphenylmethane containing 4'-diisocyanate-
The developing roller according to any one of claims 1 to 4, which is obtained by using 4,4'-diisocyanate. 6. The developing roller according to claim 1, wherein the urethane elastomer is obtained by using crude diphenylmethane-4,4′-diisocyanate as the isocyanate. 7. The developing roller according to claim 1, wherein the urethane elastomer forming the elastic layer contains a silicone powder. 8. The developing roller according to claim 1, wherein the urethane elastomer forming the elastic layer contains a charge control agent. 9. A roller-shaped or drum-shaped latent image holding member for holding an electrostatic latent image on the surface, and a non-magnetic one-component developer carried on the outer peripheral surface of the latent image holding member contacting the surface of the latent image holding member. A developing roller that rotates in conjunction with the rotational movement of the latent image carrier to attach the non-magnetic one-component developer to the electrostatic latent image on the surface of the latent image carrier to visualize the electrostatic latent image. A developing device comprising: the developing roller according to any one of claims 1 to 8 as the developing roller.