JP3075242B2 - Toner carrier and image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, which supplies toner to an image forming body such as a photoreceptor or paper holding an electrostatic latent image, thereby forming a surface of the image forming body. And a toner carrier capable of forming a high-quality image with no image unevenness. More specifically, the present invention relates to a toner carrier for forming a visible image on a toner carrier and an image forming apparatus using the toner carrier. And an image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, a one-component toner is supplied to an image forming body such as a photosensitive member holding an electrostatic latent image, and the toner is supplied to the latent image. As a method of forming an image by adhering it to the surface and visualizing the same, a pressure development method is known (US Pat. Nos. 3152012 and 3731146).

In this pressure development method, a toner carrier carrying a toner is transferred to an image forming body (photoreceptor) holding an electrostatic latent image.
In this case, the toner is adhered to the latent image of the image forming body to form an image. Therefore, the toner carrier needs to be formed of a conductive elastic body having conductivity and elasticity.

That is, in this pressure development method, as shown in FIG. 2, for example, a toner application roller 5 for supplying toner and an image forming body (photoreceptor) 6 holding an electrostatic latent image are formed. A toner carrier (development roller) 1 is disposed between the toner carrier 1 and the toner carrier 1, the image forming body 6, and the toner application roller 5 by rotating each in the direction of the arrow in the drawing.
The toner 7 is transferred to the toner carrier 1 by the toner applying roller 5.
The toner is formed into a uniform thin layer by the stratification blade 8 and the toner carrier 1 is rotated while in contact with the image forming body 6 in this state, so that the toner formed in the thin layer is removed. The latent image is adhered from the toner carrier 1 to the latent image of the image forming body 6, and the latent image is visualized. In the figure, reference numeral 9 denotes a transfer unit, which transfers a toner image to a recording medium such as paper. Reference numeral 10 denotes a cleaning unit, and the cleaning blade 11 transfers the toner image to the surface of the image forming body 6 after the transfer. The remaining toner is removed.

In this case, the toner carrier 1 must rotate while maintaining a state in which the toner carrier 1 is in close contact with the image forming body 6.
For this reason, as shown in FIG. 1, silicone rubber, NBR, E
It has a structure in which a conductive elastic layer 3 made of a conductive elastic body provided with conductivity by blending a conductive agent into an elastic rubber such as PDM or polyurethane rubber or a foam is formed. Furthermore,
To control the chargeability and adhesion of the toner 7 and to control the frictional force between the image forming body 6 and the layering blade 8,
Alternatively, a surface layer 4 made of resin or the like is provided on the surface of the conductive elastic layer 3 to prevent contamination of the photoconductor by the elastic body.

Further, as disclosed in Japanese Patent Application Laid-Open No. 58-116559 and the like, the surface of a sleeve-shaped toner carrier disposed in a non-contact state in close proximity to an image forming body (photoreceptor) is formed. There has also been proposed a method in which a non-magnetic toner having a thin layer is carried, and the non-magnetic toner is caused to fly on a photoreceptor and developed to form an image.

Further, paper such as paper or OHP paper is used as an image forming body, and the toner carried on the toner carrier is directly flown through a hole formed in the control electrode, and the image is directly formed on paper or OHP paper. There is also proposed an image forming method for forming an image.

In the image forming method using the sleeve-shaped toner carrier and the image forming method using the control electrode, the toner carrier may be charged on the toner carrier for controlling the chargeability and adhesion of the toner, the photosensitive member, or the like. Stratified blade,
A surface layer made of a resin or the like is provided on the surface of the conductive elastic layer to reduce a frictional force with another member such as a control electrode.

As a surface layer formed on the surface of the toner carrier, resins such as melamine resin, phenol resin, alkyd resin, fluororesin and polyamide resin have been proposed, and a surface layer formed of these resins is formed. By doing so, it has been proposed to improve the friction of the toner carrier and the image.

[0010]

However, in recent years,
As printers have been accelerated, fine images have been demanded, and color images have been formed, the demand for supplying a more uniform and thinner toner layer from the toner carrier to the image forming body has increased. ing. In addition to a normal environment (NN environment) having a temperature of about 22 ° C. and a humidity of about 50% RH, a low-temperature and low-humidity environment (LL) having a temperature of about 15 ° C. and a humidity of about 10% RH.
Environment), a requirement for environmental dependency that stable image formation can be obtained even in a high-temperature and high-humidity environment (HH environment) such as a temperature of 32.5 ° C. and a humidity of 85% RH, and a demand for high durability. The following problems that cannot be dealt with by the carrier have become apparent.

(1) When a toner carrier is incorporated in a printer or the like and image output is repeated for a long period of time, stripes of light and shade unevenness appear in a halftone image in a direction parallel to the paper traveling direction. This phenomenon becomes significant when used in an HH environment. (2) When the toner carrier is incorporated into a printer or the like and image output is repeated for a long period of time, fog occurs in a white background image in a direction parallel to the paper traveling direction. This phenomenon becomes remarkable in the LL environment.

The present invention has been made in view of the above circumstances, and does not cause halftone unevenness or white background fogging in an image even when used for a long period of time, and does not cause a decrease in image quality even with environmental changes. It is an object of the present invention to provide a toner carrier capable of stably obtaining a good image and an image forming apparatus using the toner carrier.

[0013]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, the occurrence of the halftone unevenness and white background fog has been reduced.
As described below, it has been found that the cause is variation or variation in the dimensions of the toner carrier. Halftone unevenness There is a portion where the pressing force of the layering blade is increased due to the dimensional variation of the toner carrier, and the toner adheres to this portion of the layering blade during repeated image formation, and the halftone image is parallel to the paper traveling direction. Streaks of uneven shading appear in the direction. Then, in the HH environment, the toner carrier expands, and the pressing force of the stratification blade becomes strong, and this phenomenon appears remarkably early. Due to the dimensional variation of the white background fogging toner carrier, there is a portion where the pressure of the stratification blade is weakened, and the toner layer on the toner carrier stratified at this portion becomes thicker, and the insufficiently charged toner and frictional charging between the toner cause The ratio of the generated oppositely charged toner increases, and fog appears in a white background image in a direction parallel to the paper traveling direction. Then, in the LL environment, the toner carrier contracts, and the pressure of the stratification blade becomes weaker, so that this phenomenon appears remarkably.

The inventor of the present invention has conducted further studies to prevent the occurrence of image defects due to dimensional variations and fluctuations. As a result, the roller-like toner carrier having a conductive elastic layer formed on the outer periphery of a good conductive shaft has been developed. A cross-linkable resin layer is formed on the surface of the body, and the toner carrier is subjected to a low-temperature and low-humidity environment at a temperature of 15 ° C. and a humidity of 10% RH and a high-temperature and high-humidity environment at a temperature of 32.5 ° C. and a humidity of 85% RH. When the sum of A and B is 0.17 mm or less when the change in the roller outer diameter of A is A and the cylindricity of the roller is B in JIS B0621 is B, the temperature and humidity fluctuate for a long time. It has been found that even when used, a good halftone image without unevenness can be obtained, fogging in a white background image can be effectively prevented, and a good image can be stably obtained over a long period of time. Is completed .

Therefore, according to the present invention, the toner is carried on the surface to form a thin layer of the toner, and in this state, the toner is supplied to the surface of the image forming body by contacting or approaching the image forming body. Thus, in the toner carrier that forms a visible image on the surface of the image forming body, a roller in which a conductive elastic layer is formed on the outer periphery of a good conductive shaft and a crosslinkable resin layer is formed on the member surface Toner carrier,
Low temperature and low humidity environment of temperature 15 ℃ and humidity 10% RH and temperature 3
When the change in the outer diameter of the roller under a high temperature and high humidity environment of 2.5 ° C. and a humidity of 85% RH is A, and the cylindricity of the roller in JIS B0621 is B, the sum of A and B is 0. 1
Provided is a toner carrier, which is not more than 7 mm.

Further, according to the present invention, a toner is carried on the surface to form a thin layer of the toner, and in this state, the toner is supplied to the surface of the image forming body in contact with or close to the image forming body. Thus, an image forming apparatus comprising a toner carrier for forming a visible image on the surface of the image forming body, wherein the toner carrier of the present invention is used as the toner carrier. provide.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The toner carrier of the present invention has a conductive elastic layer 3 formed on the outside of a good conductive shaft 2 and a resin layer 4 formed on the surface thereof, for example, like the roller shown in FIG.

The conductive elastic layer 3 is made of an elastic material obtained by adding a conductive agent to a suitable rubber material to impart conductivity. The rubber material is not particularly limited, but includes nitrile rubber, ethylene propylene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, urethane rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, and the like. One or a mixture of two or more of these rubbers can be used. In particular, nitrile rubber, urethane rubber, epichlorohydrin rubber, and ethylene propylene rubber are preferably used.

The conductive agent added to the conductive elastic layer includes an ionic conductive agent and an electronic conductive agent. Examples of ionic conductive agents include tetraethylammonium,
Perchlorates, chlorates, hydrochlorides, bromates such as tetrabutylammonium, lauryltrimethylammonium, stearyltrimethylammonium, octadecyltrimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium and modified fatty acid dimethylethylammonium Ammonium salts such as salts, iodates, borofluorides, sulfates, alkyl sulfates, carboxylates and sulfonates; perchlorides of alkali metals or alkaline earth metals such as lithium, sodium, calcium and magnesium Acid salts, chlorates, hydrochlorides, bromates, iodates, borofluorides, trifluoromethyl sulfates,
Sulfonates and the like.

Examples of the electronic conductive agent include conductive carbon such as Ketjen black and acetylene black; SA
F, ISAF, HAF, FEF, GPF, SRF, F
Carbon for rubber such as T and MT; carbon for ink subjected to oxidation treatment; pyrolytic carbon; graphite; conductive metal oxides such as tin oxide, titanium oxide and zinc oxide; and metals such as nickel and copper. be able to.

The amount of the conductive agent to be added is not particularly limited, but in the case of the above-mentioned ionic conductive agent, 0.01 to 5 parts by weight, preferably 0.05 to 5 parts by weight, based on 100 parts by weight of the rubber component. The electronic conductive agent can be about 1 to 50 parts by weight, preferably about 5 to 40 parts by weight. Thereby, the resistance of the conductive elastic layer 3 is about 10 ³ to 10 ¹⁰ Ω · cm, particularly 10 ⁴ to 10 ⁸
It is preferable to adjust to Ω · cm.

In addition to the conductive agent, other rubber additives such as known fillers and cross-linking agents can be added to the conductive elastic layer 3 as required.

The hardness of the conductive elastic layer 3 is not particularly limited, but is preferably 60 or less according to JIS-A. In this case, if the hardness exceeds 60, the toner carrier becomes hard, the contact area with the photoreceptor or the like becomes small, and good image formation may not be performed. In some cases, image sticking may occur due to toner sticking to the layering blade or the like. However, if the hardness is too low, the friction with the photoreceptor or the layering blade increases, and image defects such as jitter may occur. Therefore, it is particularly preferable that the JIS-A hardness is usually about 25 to 55.

Since the conductive elastic layer 3 is usually used in contact with an image forming body such as a photoreceptor or the like, a layering blade or the like, it is preferable that the compression set is small, specifically, 20% or less. It is particularly preferably 10% or less. In this case, polyurethane rubber is particularly preferably used because it can be designed to have a relatively small compression set.

The surface roughness of the conductive elastic layer 3 is as follows:
It is preferable to be 15 μmRz or less in JIS 10-point average density. If it exceeds 15 μmRz, it is necessary to form a thick resin layer 4 formed on the surface of the toner carrier,
As a result, the surface of the toner carrier becomes hard, damaging the toner, causing the toner to adhere to the photoreceptor and the layered blade, etc., and may cause an image defect. However, if the Rz is too small, the Rz on the surface of the toner carrier when the resin layer 4 is formed becomes too small, and the toner carrying amount may decrease to lower the image density.
It is particularly preferable to be about mRz.

The toner carrier of the present invention is used to control the chargeability and adhesion of the toner, to reduce the frictional force between the photoconductor and a layered blade, and to prevent the photoconductor from being contaminated by an elastic body. Therefore, the resin layer 4 is provided on the member surface. The resin forming the resin layer 4 is mainly made of a cross-linkable resin, is cross-linked, and has 7
Preferably, it is 0% or more. In this case, if the solvent-insoluble portion is less than 70%, there is a case where, due to long-term storage, pressure contact marks of other members in contact with the toner carrier such as the photoreceptor and the layering blade are generated, and a problem such as a black horizontal line is generated in the image. Yes, particularly preferably, the solvent-insoluble portion is at least 80%.

The crosslinkable resin forming the resin layer 4 is a resin that undergoes self-crosslinking by heat, a catalyst, air (oxygen), moisture (water), an electron beam or the like, a crosslinking agent or another crosslinking resin. Any resin that crosslinks by reaction may be used.
Examples of the crosslinkable resin include reactive groups such as a hydroxyl group, a carboxyl group, an acid anhydride group, an amino group, an imino group, an isocyanate group, a methylol group, an alkoxymethyl group, an aldehyde group, a mercapto group, an epoxy group, and an unsaturated group. With polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin,
An acrylic urethane resin, a urethane resin, an alkyd resin, a phenol resin, a melamine resin, a urea resin, a silicone resin, a polyvinyl butyral resin, and a blend thereof are exemplified.

Among these, fluorine resins, polyamide resins, acrylic urethane resins, alkyd resins, phenol resins, melamine resins, silicone resins, and blends thereof, and among these, alkyd resins, phenol resins, melamine resins, And their blends are particularly preferably used in view of the charging ability of the toner, the non-staining property of the toner, the reduction of the frictional force with the partner member, the non-staining property of the photoreceptor, and the like. Incidentally, as the catalyst for crosslinking these resins, for example, peroxide,
Examples include radical catalysts such as azo compounds, acid catalysts, basic catalysts, and alkaline catalysts.

The crosslinking agent for crosslinking the resin includes a hydroxyl group, a carboxyl group, an acid anhydride group, an amino group, an imino group, an isocyanate group, a methylol group, an alkoxymethyl group, an aldehyde group, a mercapto group, and an epoxy group. Compounds having a molecular weight of 1,000 or less, preferably 500 or less, having two or more reactive groups such as an unsaturated group in one molecule, are preferably used. Specifically, polyol compounds, polyisocyanate compounds, polyaldehyde compounds, Examples thereof include a polyamine compound and a polyepoxy compound.

The resin layer 4 is mainly composed of a cross-linkable resin cross-linked by the cross-linking agent and the like. In addition, the resin layer 4 further has an improved charging ability to the toner and a frictional force with other members. Various additives such as a charge control agent, a lubricant, a conductive agent, and other resins can be added for the purpose of reducing or imparting conductivity. Here, although not particularly limited, it is preferable to make the resistance of the resin layer 4 higher than the resistance of the conductive elastic layer 3 in order to adjust the resistance of the toner carrier. The range is 10 ⁹ to 10 ¹⁶ Ω · cm
It is. More preferably, it is 10 ¹⁰ to 10 ¹³ Ω · cm.

The method of forming the resin layer 4 is not particularly limited, but usually, a cross-linkable resin, a cross-linking agent and other additives are dissolved or dispersed in a solvent, and a dip method, a roll coater method, a doctor blade method, Alternatively, a method of applying the conductive elastic layer 3 on the conductive elastic layer 3 by a spray method or the like, drying at room temperature or at a high temperature of about 50 to 170 ° C., and curing by crosslinking is adopted.

Examples of the solvent include alcohol solvents such as methanol, ethanol, isopropanol and butanol, ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbons such as hexane. Hydrogen solvents, alicyclic hydrocarbon solvents such as cyclohexane, ester solvents such as ethyl acetate, ether solvents such as isopropyl ether and tetrahydrofuran, amide solvents such as dimethylsulfamide, halogens such as chloroform and dichloroethane. Hydrocarbonated solvents and the like, and mixed solvents thereof are preferably used.

The thickness of the resin layer 4 is usually 1 to 50 μm.
It is preferable that the thickness is about 2 to 30 μm. If the thickness of the resin layer 4 is too small, a local discharge occurs, and the image tends to have horizontal lines. On the other hand, if the thickness is too large, the toner carrier becomes hard, damaging the toner and causing damage to the photosensitive member or the photosensitive member. In some cases, image sticking may occur due to toner sticking to the layering blade and the like.

The toner carrier of the present invention has the above-mentioned conductive elastic layer 3 and the above-mentioned resin layer 4, and may be provided between the above-mentioned conductive elastic layer 3 and the above-mentioned resin layer 4 as necessary. A suitable rubber layer or resin layer may be provided. Although the resistance of the toner carrier of the present invention depends on the use, it is usually 10 ⁶ to 10 ^12.
Ω · cm, particularly about 10 ⁷ to 10 ¹⁰ Ω · cm.
Further, the surface roughness of the toner carrier on which the resin layer is formed is preferably 10 μmRz or less, particularly 1 to 8 μmRz in terms of JIS 10-point average roughness. If it exceeds 10 μm Rz, the amount of charge of the toner may be small, or a reversely charged toner may be generated, which may cause image fog.
Is too small, the amount of toner carried becomes small, and the image density may decrease.

The toner carrier of the present invention is a roller having the conductive elastic layer 3 and the resin layer 4 and has a low temperature and low humidity environment (LL environment) at a temperature of 15 ° C. and a humidity of 10% RH. When the change in the outer diameter of the roller in a high-temperature and high-humidity environment (HH environment) at 0.5 ° C. and a humidity of 85% RH is A, and the cylindricity of the roller in JIS B0621 is B, the sum of A and B is It is 0.17 mm or less.

Here, the outer diameter change A between the LL environment / HH environment is the difference between the average outer diameter when left in the LL environment and the average outer diameter when left in the HH environment in mm or mm. μ
It is represented by m. In this case, the leaving time in the LL environment / HH environment is a time until the outer diameter of the roller stabilizes in each environment, and is appropriately set. However, usually, about 300 hours is sufficient. is there.

The cylindricity B is determined according to JIS B062.
As shown in FIG. 1, a shaft (toner carrier of the present invention)
Is sandwiched between two coaxial geometric cylinders, the difference between the radii of the two cylinders when the distance between the two coaxial cylinders is minimized is expressed in mm or μm, and specifically, It can be measured as follows.

Measurement of cylindricity As shown in FIG. 3A, the roller (toner carrier) of the present invention was vertically mounted on a rotary table t, and the shaft 2
Is rotated at a predetermined speed around the axis, a plurality of measurement points are set at equal intervals in the image forming portion L along the axial direction, and the detector s is applied to each measurement point of the rotating roller, and FIG. As shown in (B), a substantially circular measurement line c is obtained from the relative fluctuation of the detector s. The measurement line c can be obtained by sandwiching the measurement line c between two coaxial geometric cylinders p ¹ and p ² and calculating the difference B (mm or μm) between the radii. Note that the number of measurement points is appropriately selected according to the length of the image forming portion L, but it is generally preferable that the number is about 20 to 40.
Further, as the detector s and the rotary table t, “Roncom 46A” manufactured by Tokyo Seimitsu Co., Ltd. having both of them is preferably used. The measurement of the cylindricity is performed in a normal environment (NN environment) at a temperature of 22 ° C. and a humidity of about 50% RH.

The toner carrier of the present invention has the above LL environment /
Sum of outer diameter change A and cylindricity B between HH environments is 0.17 m
m or less, even when used for a long time in an environment in which the temperature and humidity fluctuate, a good halftone image without unevenness can be obtained, and the occurrence of fog in a white background image can be effectively prevented. A stable image can be obtained over a long period of time. Note that a more preferable range of the A + B value is 0.14 mm or less.

The toner carrier of the present invention is used as a toner carrier such as a developing roller in an image forming apparatus such as a developing device in an electrophotographic apparatus.
As shown in FIG. 3, the toner carrier of the present invention is provided between the toner applying roller 5 for supplying toner and the photosensitive drum (image forming body) 6 holding the electrostatic latent image.
The toner 7 is supplied to the developing roller 1 composed of the toner carrier of the present invention by the toner applying roller 5 to carry the toner 7 on the surface thereof, and the toner 7 is formed into a uniform thin layer by the layering blade 8. Further, the toner is supplied from the thin layer to the photosensitive drum (image forming body) 6 and the latent image is visualized by attaching the toner to the electrostatic latent image on the photosensitive drum (image forming body) 6. Since the details of the image forming apparatus shown in FIG. 2 have been described in the related art, the description thereof will be omitted.

The image forming apparatus using the toner carrier itself of the present invention is not limited to the one shown in FIG. 2, but carries the toner on the surface to form a thin layer of the toner. Any image forming apparatus that includes a toner carrier that forms a visible image on the surface of the image forming body by supplying the toner to the surface of the image forming body in contact with or in proximity to the image forming body. It may be. For example, paper or OH
A sheet such as P paper is used as an image forming body, and the toner carried on the toner carrier is made to fly directly through a hole formed in the control electrode to directly form an image on paper or OHP paper. Is also good.

[0042]

The present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the examples.

Example 1 2.85 parts of acetylene black was blended with 100 parts (parts by weight, the same applies hereinafter) of polyisoprene polyol having a molecular weight of 2500 (OH value: 47.1) and mixed by using a mixer. A polyol composition was prepared. After stirring and defoaming this polyol composition under reduced pressure, crude MDI (NCO%: 31.7) was added to 13.3.
3 parts were added and stirred for 2 minutes, 0.001 part of dibutyltin dilaurate was added, and the mixture was stirred for 3 minutes. Next, this was cast in a mold in which a metal shaft was placed and heated to 90 ° C. in advance, and cured at 90 ° C. for 12 hours to form a conductive elastic layer on the outer periphery of the metal shaft, thereby obtaining a roller.

The surface of the obtained roller is polished and the outer diameter at which the optimum stratified blade pressure is obtained is adjusted to an NN environment (temperature: 22 ° C.,
The surface was adjusted to JIS 10 point average roughness of 7 μm Rz while adjusting to 20.00 mm using 50% RH (wet skin). The surface roughness was measured using a surface roughness meter Surfcom 590A.
(Manufactured by Tokyo Seimitsu Co., Ltd.) (the same applies to the following examples).

Next, 10% by weight of an oil-free alkyd resin and 10% by weight of a melamine resin were dissolved in toluene, respectively.
Further, the roller is immersed and pulled up in a coating liquid in which 10 parts of carbon black is added and dispersed with respect to 100 parts of the resin component, and is heated at 100 ° C. for 5 hours to have a crosslinked and cured resin layer. A roller having the structure shown in FIG. 1 was prepared. The cylindricity of the obtained roller was 0.02 mm. The cylindricity was measured at equal intervals (axial direction) in a range corresponding to the image portion of the roller using Roncom 46A (manufactured by Tokyo Seimitsu Co., Ltd.). (The same applies to the following examples).

Example 2 A roller was prepared in the same manner as in Example 1, but the polishing conditions were adjusted to obtain a roller having a cylindricity of 0.04 mm.

Example 3 A roller was prepared in the same manner as in Example 1, but the polishing conditions were adjusted to obtain a roller having a cylindricity of 0.06 mm.

Comparative Example 1 A roller was prepared in the same manner as in Example 1, but the polishing conditions were adjusted to provide a roller having a cylindricity of 0.08 mm.

Comparative Example 2 Propylene oxide and ethylene oxide were added to glycerin to give a molecular weight of 500
Polyether polyol (OH value: 33) set to 0 10
0 parts (parts by weight, hereinafter the same), 1,4-butanediol 1.0 part, silicone surfactant 1.5 parts, nickel acetylacetonate 0.5 parts, dibutyltin dilaurate 0.01 parts and acetylene black 2 Was added and mixed using a mixer to prepare a polyol composition.

The polyol composition was stirred under reduced pressure to remove bubbles, and then 17.5 parts of urethane-modified MDI was added to give 2 parts.
After stirring for 1 minute, the shaft was placed and cast into a mold previously heated to 110 ° C., and cured at 110 ° C. for 2 hours to form a conductive elastic layer on the outer periphery of the metal shaft to obtain a roller. Polish the surface of the roller to make it JIS10
The point average roughness was adjusted to 7 μmRz. A roller was formed by forming a resin layer on this roller in the same manner as in Example 1.
The cylindricity of the produced roller was 0.02 mm.

Each of the rollers obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was subjected to the following characteristic tests. Table 1 shows the results.

(1) Roller outer diameter measurement in LL environment and HH environment Roller is installed in each environment room of LL environment (temperature 15 ° C., humidity 10% RH) and HH environment (temperature 32.5 ° C., humidity 85% RH). And store it in the environment room using a dimension measuring machine (LSM300
0, manufactured by Mitutoyo Corporation), the change with time in the outer diameter at 10 locations was measured at equal intervals (axial direction) in the range corresponding to the image portion of the roller, and the change was measured until no change in the outer diameter was observed at all locations. The average of the last measured values was taken as the outer diameter of the environment.

(2) Evaluation of LL Environment White Background Each roller after measuring the outer diameter in the LL environment is mounted on the developing unit shown in FIG.
00V, blade bias -600V, average particle size 7
μm non-magnetic one-component toner, linear velocity 60 mm / sec
An image was formed in an LL environment room by reversal development while rotating at a peripheral speed of c, and the occurrence of fog in a white background image was evaluated.

(3) Evaluation of halftone image after endurance in HH environment Each roller after measuring the outer diameter in the HH environment is mounted as a developing roller 1 on the developing unit shown in FIG.
00V, blade bias -600V, average particle size 7
μm non-magnetic one-component toner, linear velocity 60 mm / sec
An image was formed in a HH environment room by reversal development while rotating at a peripheral speed of c, and 1000 sheets were continuously printed in a 5% print pattern. Thereafter, the presence or absence of shading in the halftone image was evaluated, and the stratification blade 11 in the developing unit was observed.

[0055]

[Table 1]

As shown in Table 1, LL environment / H
The sum of outer diameter change A and cylindricity B between H environments is 0.17 mm
According to the following rollers (toner carrier) of Examples 1 to 3, even when used for a long time in an environment where the temperature and humidity fluctuate, a good halftone image without unevenness can be obtained and the white background image can be obtained. Fogging can be effectively prevented,
It was confirmed that good images could be stably obtained over a long period of time.

[0057]

According to the toner carrier of the present invention, even when used for a long time, halftone unevenness and white background fog do not occur in the image, and the image quality does not deteriorate even when the environment changes. A stable image can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a toner carrier according to one embodiment of the present invention.

FIG. 2 is a schematic diagram showing an image forming apparatus according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining a method of calculating cylindricity;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 toner carrier (developing roller) 2 shaft 3 conductive elastic layer 4 resin layer 5 toner coating roller 6 image forming body (photoconductor) 7 toner 8 layering blade 9 transfer unit 10 cleaning unit 11 cleaning blade

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takahiro Kawagoe 1302-57 Aobadai, Tokorozawa-shi, Saitama (56) References JP-A-9-6128 (JP, A) JP-A-9-6093 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/08

Claims (5)

(57) [Claims] A toner is carried on the surface to form a thin layer of the toner.
In a toner carrier that forms a visible image on the surface of the image forming body by supplying the toner to the surface of the image forming body, a conductive elastic layer is formed on the outer periphery of a good conductive shaft, and Is a roller-shaped toner carrier having a cross-linkable resin layer formed thereon.
0% RH low temperature and low humidity environment, temperature 32.5 ° C, humidity 85
The sum of A and B is 0.17 mm or less, where A is the change in the outer diameter of the roller under a high-temperature and high-humidity environment of% RH, and B is the cylindricity of the roller in JIS B0621. Toner carrier. 2. The crosslinkable resin forming the resin layer,
Fluorine resin, polyamide resin, acrylic urethane resin,
The toner carrier according to claim 1, wherein the toner carrier is one or a mixture of two or more selected from an alkyd resin, a phenol resin, a melamine resin, and a silicone resin. 3. The toner carrier according to claim 1, wherein the resin layer formed on the surface of the member has an average thickness of 1 to 50 μm. 4. The method according to claim 1, wherein the conductive elastic layer is made of nitrile rubber, ethylene propylene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, urethane rubber, acrylic rubber, chloroprene rubber,
The toner carrier according to claim 1, wherein the toner carrier is one or a mixture of two or more of butyl rubber and epichlorohydrin rubber. 5. A toner is carried on the surface to form a thin layer of the toner, and in this state, the toner is brought into contact with or close to the image forming body.
5. An image forming apparatus comprising a toner carrier for forming a visible image on the surface of the image forming body by supplying the toner to the surface of the image forming body, wherein the toner carrier is used as the toner carrier. An image forming apparatus using the toner carrier according to claim 1.