JP2000010399A - Toner carrier and manufacture thereof, and image- forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner carrier excellent in durability and capable of forming a high-quality image and an image-forming device using it. SOLUTION: In this toner carrier 1 forming a visible image by carrying a thin film of toner on its surface, being brought into contact with or close to an image-forming body and feeding the toner onto the surface of the image- forming body, a first coat of resin 4a with a specific resistance of not more than 106 Ωcm is formed on the surface of a conductive elastic substrate and a second coat of resin 4b containing no conductive fine grains and having a specific resistance of not less than 1010 Ωcm is formed thereon; this toner carrier 1 is installed in an image-forming device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner carrier, a method for manufacturing the same, and an image forming apparatus using the toner carrier. More specifically, the present invention relates to a toner carrier excellent in long-term durability and capable of forming a high-quality image, a method for efficiently manufacturing the toner carrier, and an image forming apparatus equipped with the toner carrier. is there.

[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 photoconductor holding an electrostatic latent image.
As an image forming method for visualizing the toner by attaching the toner to the latent image, a pressure development method is known (US Pat.
No. 152012, No. 3731146). In this pressure development method, a toner carrier carrying toner is brought into contact with an image forming body (photoreceptor) holding an electrostatic latent image, and the toner is attached to the latent image of the image forming body. Therefore, the toner carrier needs to be formed of a conductive elastic body having conductivity and elasticity.

FIG. 2 is a schematic diagram showing an example of an image forming apparatus using the pressure development system. In the pressure development system, as shown in FIG. A toner carrier (developing roller) 1 is disposed between a toner applying roller 5 and an image forming body (photoconductor) 6 holding an electrostatic latent image, and the toner carrier 1, the image forming body 6 and the toner As the application roller 5 rotates in the direction of the arrow in the figure, the toner 7 is supplied to the surface of the toner carrier 1 by the toner application roller 5, and the toner is arranged into a uniform thin layer by the layering blade 8. . And
In this state, when the toner carrier 1 rotates while being in contact with the image forming body 6, the toner formed in a thin layer adheres from the toner carrier 1 to the latent image of the image forming body 6, and Is to be 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,
The cleaning blade 11 removes toner remaining on the surface of the image forming body after transfer.

In such an image forming apparatus using the pressure development method, the toner carrier 1 must rotate while maintaining a state in which it is in close contact with the image forming body 6. Therefore, the schematic sectional view of FIG. As shown in FIG. 2, on the outer periphery of the shaft 2 made of a good conductive material such as metal, silicone rubber, NBR (acrylonitrile-butadiene copolymer rubber), EPDM (ethylene-propylene-diene copolymer rubber), polyurethane rubber, etc. 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 elastic rubber or foam is formed. Further, a coating made of resin or the like is used to control the chargeability and adhesion of the toner 7 or to control the frictional force between the image forming body 6 and the layering blade 8 and to prevent the photoconductor from being contaminated by the elastic body. The layer 4 is provided on the surface of the conductive elastic layer 3. On the other hand, there is also proposed an image forming method of forming an image by directly flying toner carried on a toner carrier through a hole-shaped control electrode onto an image forming body made of paper such as paper or OHP paper. Have been. In addition, a thin layer of non-magnetic toner is carried on the surface of a sleeve-shaped toner carrier disposed in a non-contact state close to the image forming body (photoconductor), and the non-magnetic toner flies over the photoconductor. A method of forming an image by developing the image is also proposed (JP-A-58-116559).

[0005] In any case, on the toner carrier, the charge and adhesion of the toner are controlled, or the frictional force with other members such as a photoconductor, a layered blade, and a control electrode is reduced. In addition, a coating layer made of a resin or the like is provided on the surface of the conductive elastic layer. Incidentally, in order to obtain a bias voltage serving as a driving force for transferring the toner held on the toner carrier to the image forming body,
As a whole, the resistance value is about 10 ⁶ to 10 ¹¹ Ω · cm. In many cases, the resistance of the conductive elastic layer is set to a low resistance and the resistance of the resin coating layer is set to a high resistance in order to easily adjust the resistance. At this time, the resistance of the resin coating layer is determined by incorporating conductive fine particles such as carbon and metal oxide into the resin. However, printers and the like are accelerated, fine images are required, or color images are formed, the demands on image formation become severe, and in the conventional toner carrier as described above,
Problems that cannot be dealt with have become apparent. That is, if the number of printed sheets is increased by incorporating the toner carrier into the image forming apparatus and using it for a long time, image defects such as fog of a white image, roughness of a halftone image, and uneven shading of a black image occur. there were.

[0006]

Under such circumstances, the present invention provides a durable, long-lasting image forming apparatus that does not cause fogging of a white image, roughness of a halftone image, or shading of a black image. It is an object of the present invention to provide a toner carrier having excellent performance and an image forming apparatus using the same.

[0007]

Means for Solving the Problems The present inventors have intensively studied a toner carrier having excellent long-term durability and capable of forming a high-quality image. In the process, if the toner is used for a long time, the coating layer on the surface of the toner carrier is worn out or toner filming occurs due to friction with the toner, the toner applying roller or the layering blade, and as a result, the toner It has been found that the surface properties of the body change, the charge amount of the toner decreases, and image defects such as fog of a white image, roughness of a halftone image, and uneven density of a black image occur. The present inventors conducted further research based on this finding, and as a result, provided a first resin coating layer having a specific resistance or less on the surface of the conductive elastic base material, and further provided a conductive resin The toner carrier provided with a second resin coating layer that does not contain fine particles and has a specific resistance not less than a certain value has excellent long-term durability and can form a high-quality image. It has been found that the coating layer and the second resin coating layer can be easily manufactured by forming them by a coating method using a specific solvent. The present invention has been completed based on such findings.

That is, according to the present invention, the toner is carried on the surface.
To form a thin film that contacts or approaches the image forming body.
By supplying toner to the surface of the image forming body,
Conductive elasticity in the toner carrier that forms a visible image
The resistivity of the substrate is 10 ⁶The first tree of Ω · cm or less
A resin coating layer is provided, and conductive fine particles are
First, the specific resistance is 10^TenSecond resin coating layer of Ω · cm or more
And a toner carrier, characterized in that
An image forming apparatus provided with a toner carrier is provided.
is there. Further, the toner carrier comprises a conductive elastic base material.
For the first resin coating layer using a poor solvent for the formed elastic body
Poor solubility in the coating liquid and the resin constituting the first resin coating layer
Using a coating solution for the second resin coating layer using a solvent,
The first resin coating layer and the second resin
Manufacture by sequentially forming resin coating layers
Can be.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive elastic substrate referred to in the present invention refers to a substrate provided with a conductive elastic layer outside a shaft or the like. As illustrated in FIG. 3, the toner carrier of the present invention
A conductive elastic layer is formed on the outside of a good conductive shaft or the like, and two resin coating layers are formed on the surface thereof. FIG. 3 is a schematic view showing an example of the toner carrier of the present invention, in which a conductive elastic layer 3 is provided on the outer periphery of a shaft 2, and a first resin is provided on the surface of the conductive elastic layer 3. This shows a structure in which a coating layer 4a and a second resin coating layer 4b are sequentially formed. For the conductive elastic layer, an elastic material obtained by adding a conductive agent to an appropriate rubber-like elastic body to impart conductivity is used. Here, there is no particular limitation on the rubber-like elastic body,
It can be arbitrarily selected from those conventionally used in conventional toner carriers. Examples of the rubbery elastic body include nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber,
Examples include silicone rubber, urethane rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, and the like. These may be used alone or in combination of two or more. Among them, nitrile rubber, urethane rubber, epichlorohydrin rubber, ethylene propylene rubber, and ethylene propylene diene rubber are particularly preferable.

As the conductive agent, an ionic conductive agent or an electronic conductive agent is used. Examples of the ion conductive agent include tetraethylammonium, tetrabutylammonium,
Perchlorates, chlorates, hydrochlorides, bromine such as dodecyltrimethylammonium (eg, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (eg, stearyltrimethylammonium), benzyltrimethylammonium, modified fatty acid dimethylethylammonium Acid salt,
Ammonium salts such as iodate, borofluoride, sulfate, ethyl sulfate, carboxylate and sulfonate; and perchlorine of alkali metals and alkaline earth metals such as lithium, sodium, potassium, calcium and magnesium Acid, chlorate, hydrochloride, bromate, iodate,
Borofluoride, trifluoromethyl sulfate, sulfonate and the like can be mentioned. Examples of the electron conductive agent include conductive carbon such as Ketjen black and acetylene black; SAF, ISAF, HAF, FEF, and the like.
Rubber carbon such as GPF, SRF, FT, and MT; carbon for oxidation-treated ink, pyrolytic carbon, and graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; metals such as nickel and copper And the like.

[0011] These conductive agents may be used alone or in combination of two or more. The amount of addition is not particularly limited, but in the case of the ionic conductive agent, usually 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the rubber-like elastic body. Selected by range. On the other hand, in the case of the electronic conductive agent, it is selected in the range of 1 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of the rubber-like elastic body. Thereby, the resistance value of the conductive elastic layer is
It is preferable to adjust to a range of 10 ³ to 10 ¹⁰ Ω · cm, and particularly preferable to adjust to a range of 10 ⁴ to 10 ⁸ Ω · cm. Note that, in addition to the conductive agent, other rubber additives such as a known filler and a crosslinking agent can be appropriately added to the conductive elastic layer as needed.

This conductive elastic layer preferably has a hardness of not more than 60 ° according to JIS-A, particularly preferably in the range of 25 to 55 °. If the hardness exceeds 60 °, the toner carrier becomes hard, the contact area with the photoreceptor or the like becomes small, and there is a possibility that a good image cannot be formed. Further, the toner is damaged, and the toner adheres to the photoreceptor or the layered blade, and the image is likely to be defective. Conversely, if the hardness is too low, the friction with the photoreceptor or the stratification blade increases, and image defects such as jitter may occur.
In addition, since the conductive elastic layer is used in contact with a photoreceptor, a layered blade, or the like, the compression set is preferably small, specifically, 20% or less, particularly preferably 10% or less. In particular, polyurethane rubber is advantageous because compression set can be designed to be small. Further, the surface roughness of the conductive elastic layer is preferably 15 μmRz or less, particularly preferably 3 to 10 μmRz in terms of JIS 10-point average roughness. If the average roughness exceeds 15 μmRz, it is necessary to form a thick surface layer of the toner carrier, and as a result,
The surface of the toner carrier becomes hard, which damages the toner and causes the toner to adhere to the photoreceptor or the layered blade. Further, when Rz is too small, when the surface layer is formed, Rz on the surface of the toner carrier becomes too small, and the amount of toner carried becomes small.
The image density may decrease, which is not preferable.

In the toner carrier of the present invention, the chargeability and adhesion of the toner are controlled, or the frictional force with the photoreceptor and the layering blade is reduced, and the photoreceptor is prevented from being contaminated by the elastic body. The first resin coating layer and the second resin coating layer are sequentially provided on the surface of the conductive elastic substrate, that is, on the surface of the conductive elastic layer. Here, the first
For the resin coating layer, it is preferable to use a resin that dissolves in a poor solvent for the rubber-like elastic body constituting the conductive elastic layer.
The first resin coating layer coating solution prepared using the poor solvent,
When applied on the conductive elastic layer as described later, the conductive elastic layer does not swell, so that there is no inconvenience such as wrinkling of the coating film during drying. As such a resin,
For example, an alcohol-soluble copolymerized polyamide, a water-soluble acrylic resin, a water-soluble butyral resin, and the like are preferable. Among them, an alcohol-soluble copolymerized polyamide is particularly preferable. The first resin coating layer needs to have a specific resistance of 10 ⁶ Ω · cm or less, and preferably in a range of 10 ³ to 10 ⁶ Ω · cm. Therefore, the coating layer usually contains a conductive agent. Examples of the conductive agent include the same ones as exemplified in the description of the conductive elastic layer.

The method of forming the first resin coating layer is not particularly limited, but usually, a resin and other additives are dissolved or dispersed in a solvent to prepare a coating solution, and the coating solution is dipped. The first resin coating layer is formed by coating the conductive elastic layer on the conductive elastic layer by a coating method, a roll coater method, a doctor blade method, a spraying method, or the like, and drying and curing it at room temperature or at a temperature of about 50 to 170 ° C. Its thickness is usually in the range of about 3 to 30 μm, preferably 5 to 20 μm. On the other hand, the second
In the resin coating layer, it is preferable to use a resin that dissolves in a poor solvent for the resin constituting the first resin coating layer. By preparing a coating solution for the second resin coating layer using this poor solvent and applying it on the first resin coating layer as described later, the solvent used for forming the first resin coating layer is completely removed. It can be applied in a state where it remains without being so-called air-dried state,
It is preferable from the viewpoint of improving production efficiency.

Examples of the resin used for the second resin coating layer include ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as hexane, and cyclohexane. Alicyclic hydrocarbon solvents such as ethyl acetate, etc., isopropyl ether,
Examples thereof include resins that dissolve in ether solvents such as tetrahydrofuran, amide solvents such as dimethylsulfamide, and halogenated hydrocarbon solvents such as chloroform and dichloroethane. Examples of such resins include polyester resins, polyether resins, fluororesins, epoxy resins, amino resins, polyamide resins,
Acrylic resin, acrylic urethane resin, urethane resin,
Examples include alkyd resins, phenol resins, melamine resins, urea resins, silicone resins, polyvinyl butyral resins, and the like, and blends thereof. Among them, fluorine resin, polyamide resin, acrylic urethane resin, alkyd resin, phenol resin, melamine resin,
Silicone resins and their blends are preferred. In particular, alkyd resins, phenolic resins, melamine resins, and their blends are useful for improving the chargeability of the toner, non-staining properties for the toner, reducing the frictional force with other members, and reducing the photoreceptor. It is preferable from the viewpoint of non-staining property and the like.

The second resin coating layer in the present invention is preferably made of a cross-linked resin, and the soluble portion of the resin before cross-linking when extracted with a good solvent, for example, methyl ethyl ketone, toluene or the like, is 30% by weight or less, especially It is preferably at most 10% by weight. If the soluble portion exceeds 30% by weight, it has a relatively low molecular weight and a large amount of uncured components, resulting in insufficient durability, contamination of the photoreceptor, contamination and aggregation of the toner, abrasion of the coating layer, and an increase in the coefficient of friction. This is not preferred.
Note that the amount of the solvent-soluble portion can be calculated according to the following equation. Solvent soluble part amount (% by weight) = [(weight before solvent extraction−weight after solvent extraction) / weight before solvent extraction] × 100

The above-mentioned cross-linked resin is, for example, a cross-linkable resin capable of self-cross-linking by heat, catalyst, air (oxygen), moisture (water), electron beam, or the like, or a reaction with a cross-linking agent or another cross-linkable resin. A resin obtained by subjecting a crosslinkable resin to a crosslinking treatment. Here, examples of the crosslinkable resin include 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. Resin having a reactive group (crosslinkable group), specifically, polyester resin, polyether resin, fluororesin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, Melamine resin, urea resin, silicone resin, polyvinyl butyral resin and the like can be mentioned. These may be used alone or in combination of two or more. Among these, a fluororesin, a polyamide resin, an acrylic urethane resin, an alkyd resin, a phenol resin, a melamine resin, a silicone resin and a blend thereof are preferable. In particular, an alkyd resin, a phenol resin, a melamine resin and a blend thereof are preferable. It is preferable from the viewpoints of charging ability of toner, non-staining property to toner, reduction of frictional force with other members, non-staining property to photoreceptor, and the like.

Examples of the catalyst include radical catalysts such as peroxides and azo compounds, acid catalysts, basic catalysts, alkali catalysts, and the like. These are appropriately selected according to the type of the crosslinkable resin. You. Examples of the crosslinking agent 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. A compound having a molecular weight of about 1000 or less, preferably two or more compounds having a molecular weight of 500 or less, specifically a polyol compound,
Polyisocyanate compounds, polyaldehyde compounds, polyamine compounds, polyepoxy compounds, and the like.
These are appropriately selected according to the type of the crosslinkable resin.
In the present invention, this second resin coating layer does not contain conductive fine particles, and its specific resistance needs to be 10 ¹⁰ Ω · cm or more, and preferably 10 ¹⁰ to 10 ¹⁶ Ω · cm.
Range.

Various additives such as a charge control agent, a lubricant, and other resins are added to the second resin coating layer for the purpose of improving the chargeability to the toner and reducing the frictional force with other members. Can be. The method for forming the second resin coating layer is not particularly limited, but usually, a coating liquid is prepared by dissolving or dispersing a crosslinkable resin, a crosslinking agent, and other additives in a solvent. Is applied on the first resin coating layer by a dip method, a roll coater method, a doctor blade method, a spray method, or the like, dried at room temperature or at a temperature of about 50 to 170 ° C., and cured by crosslinking to form a second resin coating layer. To form Its thickness is usually about 1 to 20 μm, preferably 3 to 10 μm.
It is in the range of μm. The thickness of the second resin coating layer is 1 μm
If it is less than 20 μm, local discharge may occur, and horizontal white lines may be easily generated in the image. If it exceeds 20 μm, the toner carrier becomes hard and damages the toner, and the toner adheres to the photoreceptor or the layered blade. Occurs, causing image failure. The resistance value of the toner carrier of the present invention is usually 1
0 ⁴ to 10 ¹⁰ Ω · cm, preferably 10 ⁴ to 10 ⁸ Ω · cm
cm.

The surface roughness of the toner carrier, that is, the surface roughness of the second resin coating layer is preferably 10 μmRz or less, particularly preferably 1 to 8 μmRz, in terms of JIS 10-point average roughness. If it exceeds 10 μmRz, the amount of charge of the toner becomes small, or a reversely charged toner is generated, which causes image fog, which is not preferable. If Rz is too small, the amount of toner carried is reduced, and the image density is undesirably reduced. The present invention also provides an image forming apparatus equipped with the above-mentioned toner carrier. There is no particular limitation on the type of the image forming apparatus of the present invention, for example, (1)
A pressure developing method in which an image is formed by bringing a toner carrier carrying a toner into contact with an image forming body (photoreceptor) holding an electrostatic latent image and attaching toner to the latent image of the image forming body; (2) a method of forming an image by directly flying toner carried on a toner carrier through a hole-shaped control electrode on an image forming body made of paper sheets, and (3) an image forming body (photosensitive A non-magnetic toner layered in a thin layer is carried on the surface of a sleeve-shaped toner carrier disposed in a non-contact state in close proximity to the photoconductor, and the non-magnetic toner is developed by flying the photoconductor onto a photoconductor. , Or any other method. As an example of the image forming apparatus of the present invention, the apparatus of the pressure developing system shown in FIG.

[0021]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The characteristics of the toner carriers prepared in Examples and Comparative Examples were determined according to the following procedure. (1) Layer thickness of surface layer A vertical section of the toner carrier was observed and measured with a scanning electron microscope.

(2) Solvent-soluble portion of second resin coating layer A glass plate is prepared separately from the toner carrier, and the coating liquid used for forming the second resin coating layer of each toner carrier is applied to the glass. It was applied on a plate, and the coating film was heated and crosslinked and cured under the same conditions as in the preparation of each toner carrier. Thereafter, the entire glass plate was immersed in methyl ethyl ketone at 25 ° C. for 24 hours, dried, and the weight of the coating film before and after immersion was measured. 2 The amount of the solvent-soluble portion of the resin coating layer was defined as the amount. Solvent soluble part amount (% by weight) = [(weight before solvent extraction−weight after solvent extraction) / weight before solvent extraction] × 100 (3) Volume resistivity of coating layer A copper plate was prepared, and The coating solution was applied on the copper plate using the coating solution used for forming the coating layer, and the coating film was heated under the same conditions as those of the respective toner carriers to perform crosslinking and curing. Thereafter, the resistance between the copper plate and the measurement electrode was measured to obtain the specific resistance of the coating layer.

(4) Resistance of Toner Carrier Each toner carrier on a copper plate is 500 g on each side.
And applied a voltage of 100 V using a resistivity meter R8340A (manufactured by Advantest) to measure the resistance value. (5) Toner Conveyance Amount of each toner carrier as a developing roller is mounted on the developing unit of the image forming apparatus shown in FIG. 2 and is rotated at a peripheral speed of 50 mm / sec. A thin toner layer was formed, the thin toner layer was sucked, the weight was measured, and the value obtained by dividing the weight by the sucked area was defined as the toner transport amount. (6) Amount of toner charge Each toner carrier is mounted as a developing roller on the developing unit of the image forming apparatus shown in FIG. 2 and rotated at a peripheral speed of 50 mm / sec. A thin toner layer was formed, and the thin toner layer was sucked and introduced into a Faraday gauge, and the charge amount was measured.

(7) Image Evaluation Each toner carrier is set as a developing roller in the developing unit of the image forming apparatus shown in FIG.
A non-magnetic one-component toner having an average particle diameter of 7 μm was used at a linear velocity of 60 mm /
An image was formed by reversal development while rotating at a peripheral speed of seconds, and image evaluation on a white background, a halftone image, and a black background image was performed before and after a 3000-sheet durability test. Evaluation Criteria <Fog> ○: No fog ×: White background fog <Black image> ○: Normal density ×: Light density

Example 1 Polyisoprene polyol having a molecular weight of 2500 (OH value:
(47.1 mg KOH / g) and 2.85 parts by weight of acetylene black were mixed with 100 parts by weight, and mixed using a mixer to prepare a polyol composition. After defoaming by stirring this polyol composition under reduced pressure, crude MDI (crude meta-xylylene diisocyanate) (NCO weight%; 31.7)
13.33 parts by weight was added and stirred for 2 minutes, and 0.001 parts by weight of dibutyltin dilaurate was added and stirred for 3 minutes. Next, this was cast in a mold in which a shaft was placed and heated to 90 ° C. in advance, and cured at 90 ° C. for 12 hours to form a conductive elastic body on the outer periphery of the metal shaft to obtain a roller. The surface of the obtained roller is polished and the surface is JIS 10-point average roughness 1
It was adjusted to 0 μm Rz. Next, soluble copolymer nylon (CM8000, manufactured by Toray Industries, Inc.) was dissolved in methanol to a concentration of 10% by weight, carbon black (Printex35, manufactured by Degussa) was added to the resin at 50% by weight, and glass beads were further added. And then 5 on a paint shaker
By shaking for a time, a coating solution was prepared. The roller was immersed in the coating liquid, pulled up, and air-dried for 1 hour to form a first resin layer. Next, an oil-free alkyd resin (M6402, manufactured by Dainippon Ink and Chemicals, Inc.), a melamine resin (145 manufactured by Dainippon Ink and Chemicals, Inc.) and silicone oil (KR211, manufactured by Shin-Etsu Silicone Co., Ltd.) were used in methyl ethyl ketone at a resin weight ratio of 56:20. : 24, and dissolved to give a total resin concentration of 20% by weight to prepare a coating liquid. The roller provided with the first resin layer was immersed in the coating liquid and pulled up to form a second resin layer. At that time, no elution into the first resin layer was confirmed. Next, this was heated at 110 ° C. for 4 hours to obtain a toner carrier having a three-layer structure shown in FIG. 3 and having a crosslinked and cured second resin layer.

This toner carrier is replaced with a commercially available LBP (NEC)
2200X), and measured the initial image, toner transport amount, and toner charge amount. Next, an image sample having a print density of 5% was subjected to a 3,000-sheet passing test. After the printing, the image was evaluated again, and the toner conveyance amount and the toner charge amount were measured. The obtained image is good both at the beginning and after the endurance,
The toner conveyance amount and the toner charge amount were hardly reduced. The results are shown in Table 1. Comparative Example 1 In Example 1, except that the first resin layer was not provided and the resin concentration of the coating liquid for forming the second resin layer was changed to 35% by weight.
A toner carrier was manufactured in the same manner as in Example 1. The results are shown in Table 1. Since the resistance value of the toner carrier became extremely high, a predetermined developing bias could not be secured, and in the initial image, black density was insufficient and white background fogging occurred on the front side, resulting in image failure.

Comparative Example 2 A toner was prepared in the same manner as in Comparative Example 1, except that carbon black was added to the second resin layer forming coating solution in an amount of 25% by weight with respect to the resin. A carrier was produced. The results are shown in Table 1. Although the initial image and the initial charge amount were good, the toner charge amount after the printing paper-passing test similar to that in Example 1 was low, and the image after the durability had a lot of white background fog. Comparative Example 3 A toner carrier was manufactured in the same manner as in Example 1, except that the second resin layer was not provided. The results are shown in Table 1. The initial charge amount was rather low, and the toner charge amount was remarkably reduced by the printing paper-passing test, and the image after the endurance had much white background fog.

[0028]

[Table 1]

[Note] CM8000: Soluble copolymer nylon manufactured by Toray Industries, weight%
Is a value based on the total amount with methanol. CB: Carbon black, Printex 35 M6402 manufactured by Degussa Co., Ltd .: Oil-free alkyd resin manufactured by Dainippon Ink and Chemicals, Inc. L145: Melamine resin manufactured by Dainippon Ink and Chemicals, Inc. KR211: Silicone resin manufactured by Shin-Etsu Silicone Co., Ltd. M6402 / L145 / KR211 is weight%. , And the value of the total amount of resin relative to the total of these resins and methyl ethyl ketone. MEK: Methyl ethyl ketone

[0030]

The toner carrier of the present invention is excellent in durability without generation of fog of a white image, roughness of a halftone image or unevenness of density of a black image even when used for a long period of time. It is suitably used as a toner carrier of various image forming apparatuses.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a toner carrier.

FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus using a pressure development method.

FIG. 3 is a schematic sectional view showing an example of the toner carrier of the present invention.

[Explanation of symbols]

 1: toner carrier (developing roller) 2: shaft 3: conductive elastic layer 4: coating layer 4a: first resin coating layer 4b: second resin coating 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 Continued on the front page (72) Inventor Hiroshi Kaneda 3-21-7, Ogawanishimachi, Kodaira-shi, Tokyo (72) Inventor Hiroshi Harashima 43-1-206, Sachigaoka, Asahi-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Kawagoe Takahiro 1302-57 Aobadai, Tokorozawa-shi, Saitama F-term (reference) 2H077 AD06 AD13 AD36 EA14 FA01 FA12 FA22 FA25 GA17 3J103 AA02 AA15 AA51 FA12 FA15 FA30 GA02 GA52 HA03 HA12 HA20 HA41 HA46 4J038 CD092 CE071 CG141 DB002DD DF 002 DF002 PA02

Claims (7)

[Claims] 1. A toner carrying member which forms a visible image by carrying a toner on the surface to form a thin film thereof and contacting or approaching the image forming body and supplying the toner to the surface of the image forming body. A first resin coating layer having a specific resistance of 10 ⁶ Ω · cm or less is provided on the surface of the conductive elastic base material, and no conductive fine particles are contained thereon;
A toner carrier having a second resin coating layer of ¹⁰ Ω · cm or more. 2. The toner carrier according to claim 1, wherein the resin constituting the first resin coating layer is a resin soluble in a poor solvent for the elastic body constituting the conductive elastic substrate. 3. The toner carrier according to claim 1, wherein the resin constituting the first resin coating layer is an alcohol-soluble copolymerized polyamide resin. 4. The resin constituting the second resin coating layer comprises a first resin coating layer.
4. The toner carrier according to claim 1, wherein the resin is a resin soluble in a poor solvent for the resin constituting the resin coating layer. 5. The method according to claim 1, wherein the second resin coating layer is formed of a crosslinked resin, and the soluble portion of the resin before the crosslinking is extracted with a good solvent.
5. The toner carrier according to claim 1, wherein the amount of the toner carrier is 0% by weight or less. 6. A method of applying a coating liquid on the surface of a conductive elastic base material to form a first resin coating layer and a second resin coating layer in order, and forming a first resin coating layer when manufacturing a toner carrier. The layer coating liquid uses a poor solvent for the elastic body constituting the conductive elastic substrate, and the second resin coating layer coating liquid contains a poor solvent for the resin constituting the first resin coating layer. 6. The method for producing a toner carrier according to claim 1, wherein the toner carrier is used. 7. A toner carrying member that forms a visible image by carrying toner on the surface to form a thin film thereof and supplying toner to the surface of the image forming material in contact with or in proximity to the image forming material. An image forming apparatus, wherein the toner carrier according to any one of claims 1 to 5 is used as the toner carrier in a mounted image forming apparatus.