JP2001034062A - Developer carrier and image forming apparatus - Google Patents

Abstract

(57) [Problem] To provide a developer carrier excellent in long-term durability and capable of forming a high-quality image. SOLUTION: The developer is carried on the surface to form a thin film thereof, and in this state, the developer is supplied to the surface of the image forming body by contacting or approaching the image forming body, whereby the surface of the image forming body is supplied. In a developer carrier for forming a visible image on the
Developer carrying member, the surface of the conductive elastic layer, the resin 100 parts by weight and 70 parts by weight of more than 200 parts by weight or less of 10 ⁰ -
A developer carrier having a coating layer made of a material containing a conductive powder of 10 ⁵ Ω · cm, and an image forming apparatus equipped with the developer carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer carrier and an image forming apparatus, and more particularly, to an image forming apparatus such as a copying machine, a facsimile, a printer, and the like. A developer carrying member for supplying a developer to the image forming body to form a visible image on the surface of the image forming body, providing a high-quality image without image unevenness, and a characteristic in long-term use. The present invention relates to a developer carrier having small changes and excellent durability, and an image forming apparatus equipped with 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 (developer) is supplied to an image forming body such as a photoconductor holding an electrostatic latent image. A pressure development method is known as an image forming method for visualizing toner by attaching toner to a latent image (US Pat.
No. 52012, No. 3731146, etc.). In this pressure development method, a toner carrier (developer carrier) carrying a toner is brought into contact with an image forming body (photoreceptor) holding an electrostatic latent image, and the toner is transferred to the latent image of the image forming body. The toner carrier is formed of a conductive elastic material having conductivity and elasticity. That is, in this pressure development method, as shown in FIG. 2, for example, a toner is applied between a toner applying roller 5 for supplying toner and an image forming body (photoconductor) 6 holding an electrostatic latent image. A carrier (development roller) 1 is disposed, and the toner 7 is rotated by the toner carrier 1, the image forming body 6, and the toner application roller 5 in the direction of the arrow in FIG.
Is supplied to the surface of the toner carrier 1, and the toner is formed into a uniform thin film by the layering blade 8. Then, 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 The image is made visible. In the drawing, 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 the toner remaining on the surface of the image forming body 6 after the transfer.

In such an image forming apparatus using the pressure development method, 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. As shown in the figure, a conductive agent is blended with an elastic rubber or foam such as silicone rubber, acrylonitrile butadiene rubber, ethylene propylene rubber, polyurethane rubber, etc. around the outer periphery of the shaft 2 made of a good conductive material such as metal. The structure is such that a conductive elastic layer 3 made of a conductive elastic body provided with is formed. further,
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 coating layer 4 made of a resin or the like is provided on the surface of the conductive elastic layer 3 in order to prevent contamination of the image forming body by the elastic body. On the other hand, an image forming method for forming an image by causing a toner carried on a toner carrier to fly in a straight line through an aperture-shaped control electrode on an image forming body made of paper such as paper or OHP paper is also proposed. Have been. Also, 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 (photoreceptor), and this is placed on the image forming body. A method of forming an image by developing by flying is also proposed (JP-A-58-116559).

[0004] In any case, the toner carrier is provided on the toner carrier for controlling the chargeability and adhesion of the toner or for reducing the frictional force with other members such as an image forming body, a layered blade, and a control electrode. To this end, a coating layer made of a resin or the like is provided on the surface of the conductive elastic layer. By the way, in order to obtain a bias voltage which is a driving force for transferring the developer held on the developer carrier to the image forming body,
The resistance value of the entire development carrier is about 10 ⁶ to 10 ¹¹ Ω. In many cases, in order to easily adjust the resistance, the specific resistance of the conductive elastic layer is set to be low, and the specific resistance of the coating layer made of resin is set to be high. At this time, the adjustment of the specific resistance of the coating layer is performed by adding a conductive powder such as carbon or metal oxide to the resin forming the coating layer. The present inventors have previously developed melamine resins, phenol resins, alkyd resins, fluororesins,
A developer carrier using a resin such as a polyamide resin for the coating layer has been proposed as a developer carrier capable of improving friction and an image.

[0005]

However, recently, the demand for image formation has become strict due to the speeding up of printers and the like, the demand for fine images, and the development of color images. Various problems that cannot be dealt with by the developer carrier have become apparent. In other words, when the developer carrier is incorporated in a printer or the like and used for a long period of time and the number of printed sheets increases, problems such as image fogging in a white background image and unevenness in density reduction in a black image become apparent. Was. The present invention has been made in view of the above circumstances, and does not cause image defects such as fog on a white background image and uneven density reduction in a black image even when used for a long period of time. It is an object of the present invention to provide an image forming apparatus equipped with a.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on a developer carrying member which is excellent in long-term durability and can form a high-quality image, and as a result, has obtained the following knowledge. That is, the fogging of the white background image and the density unevenness of the black image are caused by friction between the developer carrier and the developer, the developer application roller or the laminating blade when the developer carrier is used for a long time. In addition, the developer carrier surface coating layer is worn out, and a large amount of developer filming occurs on the surface of the coating layer. As a result, the surface of the developer carrier changes, and the charge amount of the developer decreases. It has been found that this can occur. As a result of further research, the present inventors have found that a developer carrier having a coating layer made of a resin containing an appropriate amount of conductive powder having a specific range of specific resistance is provided on the surface of the conductive elastic layer. However, it was found that it was possible to form a high quality image with excellent long-term durability. The present invention has been completed based on such findings. That is, the present invention
A developer is supported on the surface to form a thin film, and in this state, the visible image is formed on the surface of the image forming body by supplying the developer to the surface of the image forming body by contacting or approaching the image forming body. In the developer carrier to be formed, 100 parts by weight of the resin and 70 parts by weight of the
Of 200 parts by weight or less than the weight part 10 ⁰ ~10 ⁵ Ω · c
a developer carrying member having a coating layer made of a material containing a conductive powder of m. Further, the present invention provides a method in which a developer carrier is mounted, and a developer is carried on the surface of the developer carrier to form a thin film of the developer, and the developer carrier is brought into contact with or close to the image forming body. An image forming apparatus that forms a visible image on the surface of the image forming body by supplying a developer to the surface of the image forming body, wherein the developer supporting body is used as the developer supporting body. An image forming apparatus is provided.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a developer carrier of the present invention has a conductive elastic layer 3 formed on the outer periphery of a good conductive shaft 2 and a coating layer formed on the surface of the conductive elastic layer 3. 4 is formed. As the shaft 2, any material having good conductivity can be used, but usually, a metal such as a metal core bar made of a solid metal body or a metal cylindrical body having a hollow inside is used. A shaft made of is used. The conductive elastic layer 3 is made of an elastic material obtained by adding a conductive agent to an appropriate rubber material to impart conductivity. here,
There is no particular limitation on the rubber material. For example, nitrile rubber, ethylene propylene rubber, ethylene propylene diene 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 may be used, and these may be used alone or in combination of two or more. Among them, one or more selected from among butadiene rubber, ethylene propylene rubber and urethane rubber are particularly preferred. Are preferred.

On the other hand, conductive agents added to these rubber materials include an ionic conductive agent and an electronic conductive agent. Examples of the former ionic conductive agent include tetraethylammonium, tetrabutylammonium, lauryltrimethylammonium and the like. Perchlorate, chlorate, hydrochloride, such as octadecyltrimethylammonium, benzyltrimethylammonium, modified aliphatic dimethylethylammonium, such as dodecyltrimethylammonium, hexadecyltrimethylammonium, stearyltrimethylammonium;
Bromate, iodate, borofluoride, sulfate,
Ammonium salts such as alkyl sulfates, carboxylates, and sulfonates; perchlorates, chlorates, hydrochlorides, bromates, and iodines of alkali metals or alkaline earth metals such as lithium, sodium, calcium, and magnesium Acid salt,
Borofluoride, trifluoromethyl sulfate, sulfonate and the like can be mentioned. Examples of the electronic conductive agent include conductive carbon blacks such as Ketjen black and acetylene black; SAF, ISAF, HAF, F
Carbon black for rubber such as EF, GPF, SRF, FT, and MT; carbon black for ink after oxidation treatment, pyrolytic carbon black, graphite; conductive metal oxide such as tin oxide, titanium oxide, and zinc oxide; nickel And powders of metals such as copper.

These conductive agents may be used alone,
You may use it combining the above. The amount of addition
Although not particularly limited, in the case of an ion conductive agent,
0.01 to 5 parts by weight based on 100 parts by weight of the rubber material
Parts, preferably in the range of 0.05 to 2 parts by weight.
1 to 50 parts by weight, preferably 5
It can be in the range of ４０40 parts by weight. This conductive additive
By adjusting the addition amount, the specific resistance of the conductive elastic layer is reduced to 10
^Three-10 ¹²Ω · cm, especially 10^Four-10⁸Ω ・ cm range
It is preferable to adjust to the surroundings. In addition, this conductive elastic layer
May be a conventionally known filler, if necessary, in addition to the conductive agent.
Add other rubber additives, such as crosslinking agents, as appropriate
Can be. This conductive elastic layer has a hardness of Asker C type.
The angle is preferably in the range of 40 to 80 °, especially 50 to 75 °.
Good. When the hardness exceeds 80 °, the developer carrier becomes hard.
And the contact area with image formation etc. becomes smaller,
Image formation may not be possible and the developer may be damaged.
To fix toner on the image forming body or layering blade
Occurs, which causes image defects. Conversely, low hardness
If it becomes too high, friction with the image forming body and
Large, and image defects such as jitter may occur.
You.

Since the conductive elastic layer is used in contact with an image forming body, a layered blade or the like, it is preferable that the compression set is small, specifically, 20% or less, particularly 10% or less.
% Or less is preferable. In particular, polyurethane rubber is particularly preferable because the compression set can be designed to be small. 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 coating layer forming the surface of the developer carrying member, and as a result, the surface of the developer carrying member becomes hard and damages the developer, resulting in an image forming member. And the developer adheres to the stratification blade, which results in image failure, which is not preferable. On the other hand, if the Rz is too small, when the coating layer is formed, the Rz on the surface of the developer carrying member becomes too small, and the amount of the developer carried becomes small, so that the image density may be reduced. The surface roughness was measured using a surface roughness meter “Surfcom 590A” (manufactured by Tokyo Seimitsu Co., Ltd.) in the circumferential direction at a measurement length of 2.4 mm, a measurement speed of 0.3 mm / sec, and a cutoff wavelength of 0 mm. It is a value obtained by measuring 300 points or more at 0.8 mm so that there is no deviation in the shaft direction and circumferential direction of the roller (the same applies to the following).

In the developer carrying member of the present invention, in order to control the chargeability and adhesion of the developer, to reduce the frictional force with an image forming member, a layered blade, or the like, or
In order to prevent the image forming body from being contaminated by the elastic body, a coating layer made of a resin or the like is provided on the surface of the conductive elastic layer. This coating layer is preferably formed of a material containing a resin having a glass transition point of 10 ° C. or lower, and the resin preferably has a glass transition point of −50 to 0 ° C. When a resin having a glass transition point of more than 10 ° C. and 40 ° C. or less is used, the physical properties of the coating layer greatly change depending on the use environment temperature, and there is a possibility that the transport amount and charge amount of the developer may vary. When a resin having a glass transition point exceeding 40 ° C. is used, the coating layer becomes brittle, so that it cannot follow the deformation of the conductive elastic layer, and thus the coating layer is easily broken. The dynamic elastic modulus E ′ of the coating layer is 10 ⁷ to
It is preferably 10 ^9.8 dyn / cm ² , particularly preferably 10 ⁸ to ^109.6 dyn / cm ² . The loss tangent tan δ of the coating layer is preferably 0.7 or less, particularly preferably 0.05 to 0.5. Here, the loss tangent tan δ refers to the ratio of the dynamic loss E ″ to the dynamic elastic modulus E ′ (when stress is applied to the sample). The dynamic elastic modulus E ′ of the coating layer is 10 ⁷ to 10. ^9.8 dyn / cm
² , and the loss tangent tan δ is 0.7 or less, no filming of the developer or cracking of the coating layer occurs during the durable printing, and the image on the white background image is obtained when the developer carrier is used for a long time. Fogging can be prevented, and the occurrence of image noise can be prevented without causing insufficient density in a solid black image.

The resin used for forming the coating layer according to the present invention includes a crosslinkable resin. Here, the crosslinkable resin refers to a resin that is self-crosslinked by heat, a catalyst, air (oxygen), moisture (water), an electron beam, or the like, or a resin that is crosslinked by a reaction with a crosslinking agent or another crosslinkable resin. Examples of such crosslinkable resins include hydroxyl, carboxyl, acid anhydride, amino, imino, isocyanate, methylol, alkoxymethyl, aldehyde, mercapto, epoxy, and unsaturated groups. Resin, polyamide resin, acrylic urethane resin, alkyd resin, phenol resin, melamine resin, silicone resin, urethane resin, polyester resin, polyvinyl acetal resin, epoxy resin, polyether resin, amino resin, urea resin Acrylic resins, acrylic-modified silicone resins, styrene-butadiene resins, and the like, and mixtures thereof, may be used. Among them, fluorine resin, polyamide resin, acrylic urethane resin, alkyd resin, phenol resin, melamine resin, silicone resin, urethane resin, polyester resin, polyvinyl acetal resin, epoxy resin, acrylic resin, acrylic modified silicone resin, styrene butadiene Resins and mixtures thereof are preferred. Particularly, alkyd resins, phenol resins, melamine resins, polyester resins, acrylic resins, acryl-modified silicone resins, styrene-butadiene resins and mixtures thereof are suitable for the chargeability of the developer and the non-staining property to the developer. This is preferable from the viewpoints of reduction in frictional force with other members, non-contamination of the image forming body, and the like.

Examples of the catalyst include radical catalysts such as peroxides and azo compounds, acid catalysts, and basic catalysts. Examples of the crosslinking agent 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. A compound having a molecular weight of 1,000 or less having two or more groups in one molecule, preferably a compound having a molecular weight of 500 or less,
For example, polyol compounds, polyisocyanate compounds, polyaldehyde compounds, polyamine compounds, polyepoxy compounds and the like can be mentioned. The coating layer according to the present invention,
A solvent having an insolubility of 70% by weight or more is preferable. If the insolubility is less than 70% by weight, a contact mark of a member which is in contact with a toner carrier, such as an image forming member or a layered blade, after being left for a long period of time. As a result, a problem such as a horizontal black line may occur in the image. Particularly, those having a solvent insolubility of 80% by weight or more are preferable.

The coating layer according to the present invention comprises the above-mentioned crosslinkable resin or the like.
The main component is
Further improvement of power, reduction of frictional force with other members and conductivity
Charge control agent, lubricant, conductive agent, etc.
Various additives such as resin can be contained. Departure
In a light developer carrier, the resistance of such a coating layer
Is higher than the resistance of the conductive elastic layer.
It is preferable to adjust the resistance of the holding body, and this coating layer is preferable.
New specific resistance is 10⁷-10¹⁶Ω · cm
Especially 10 ⁹-10¹⁴The range of Ω · cm is preferable. Suffered
In order to set the specific resistance of the covering layer in such a range, the resin 10
0 parts by weight and more than 70 parts by weight and not more than 200 parts by weight
⁰-10^FiveCoated with material containing conductive powder of Ωcm
This can be achieved by forming a layer. Inherent of conductive powder
The resistance is preferably 10⁰-10^ThreeΩ · cm, tree
The content of the conductive powder to 100 parts by weight of the fat is preferably
Or 80 to 170 parts by weight. Specific resistance is 10^FiveΩ
cm or less, the resistivity of the coating layer
Is too high and conductive to achieve the desired resistivity
As the amount of powder becomes excessive, the coating layer becomes brittle and
The coating layer may crack. Also, 10⁰Less than Ω · cm
The use of conductive powder makes it possible to use the developer
If the coating layer wears, the conductive powder is exposed on the surface,
As a result, the surface resistance of the coating layer is significantly reduced, and
Insufficient charge of the developer on the carrier, fog on white background
This may cause image defects such as uneven density reduction of black images,
The goal of the invention is not achieved. Such conductive powder
Specifically, a tin oxide conductive layer is formed on the surface of barium sulfate.
Formed Pastoran TYPE-IV4410B [Mitsui Kin
2 × 10Ω · cm] and Pastoran T
YPE-IV4350 [Mitsui Metal Mining Co., Ltd., 3 × 1
0^FourΩ · cm], tin oxide conductive film on the surface of titanium oxide
Formed with W-1-P [Mitsubishi Materials Corporation,
10¹Ω · cm], tin oxide T-1 [Mitsubishi Materia
Le Co., Ltd., 10⁰Ω · cm], 2 of conductive zinc oxide
3-K [2 × 10 by Hakusui Chemical Industry Co., Ltd.^TwoΩ ・ c
m] and mixtures thereof. In addition,
The specific resistance of the conductive powder is AS-2 manufactured by Ando Electric Co., Ltd.
Using 0646 and SE-43 type powder electrodes
Put powder between electrodes, 100kg / cm^TwoBetween the electrodes with
And measure the electrical resistance with a tester.
This is the value obtained by converting the thickness of the powder when pressed.
You.

The resistance of the developer carrying member is 10 ⁶ to 10
¹² Ω is preferred, and 10 ⁷ to 10 ¹⁰ Ω is particularly preferred. Further, the surface roughness of the developer carrying member on which the coating layer is formed is determined by JI
S10 average roughness of 10 points or less, particularly 0.3 to 8
It is preferably set to μmRz. This average roughness is 10μ
If it exceeds mRz, the amount of charge of the developer becomes small or a reverse-charged developer is generated, which causes image fog, which is not preferable. On the other hand, if Rz is too small, the amount of developer carried is reduced, and the image density may be reduced. The method for forming the coating layer on the developer carrier of the present invention is not particularly limited, but usually, a coating solution obtained by dissolving or dispersing a crosslinkable resin, a crosslinker, and various additives as necessary. Dipping method, roll coater method, doctor blade method,
After applying it on the conductive elastic layer by spraying, etc.,
It is formed by drying at room temperature or at a temperature of about 50 to 170 ° C., and crosslinking and curing.

The thickness of the coating layer can be about 1 to 50 μm, but is particularly preferably in the range of 2 to 30 μm. If the thickness of the coating layer is too small, local discharge occurs, and horizontal white lines are likely to occur in the image. On the other hand, if the thickness is too large, the developer carrying member becomes hard and damages the developer, causing the developer to adhere to the image forming body or the layered blade, thereby causing an image defect. Examples of the solvent used for preparing the coating liquid 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; Aliphatic hydrocarbon solvents such as hexane; alicyclic hydrocarbon solvents such as cyclohexane; ester solvents such as ethyl acetate; ether solvents such as isopropyl ether and tetrahydrofuran; amide solvents such as dimethylformamide; Examples thereof include halogenated hydrocarbon solvents such as chloroethane and the like, and mixed solvents thereof. In the present invention, ketone solvents and mixed solvents of ketone solvents and aromatic hydrocarbons are particularly preferably used.

The developer carrying member of the present invention is used by being incorporated as a developing roller or the like in an image forming apparatus such as a developing device in an electrophotographic apparatus. For example, as shown in FIG. Drum (image forming body) holding toner applying roller 5 and electrostatic latent image
6, the developer carrying member of the present invention is disposed as a developing roller 1, and a toner 7 is carried by a toner applying roller 5, which is formed into a uniform thin layer by a layering blade 8. From the photosensitive drum (image forming body) 6
And makes toner adhere to the electrostatic latent image on the photosensitive drum (image forming body) 6 to visualize the latent image. The details of the image forming apparatus shown in FIG. Note that the image forming apparatus to which the developer carrying member of the present invention is attached is not limited to the one shown in FIG. 2, and the developer is carried on the surface to form a thin layer of the developer. Any material may be used as long as it forms a visible image on the surface of the image forming body by supplying a developer to the surface of the image forming body in contact with or close to the forming body. For example, paper such as paper or OHP paper is used as an image forming body, and the developer carried on the developer carrier is directly scattered through the holes formed in the control electrodes, and directly onto the paper or OHP paper. It may be one that forms an image.

As the developer carried on the developer carrier of the present invention, a non-magnetic one-component toner is preferably used, but a magnetic one-component developer can also be used. Even when monochrome image printing is performed using toner, the developer carrier and the image forming apparatus of the present invention can be suitably used.

[0019]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, the toner carrier obtained in each of Examples and Comparative Examples was subjected to a characteristic test in the following manner. (1) Layer Thickness of Coating Layer A vertical section of the roller to be tested was observed and measured with a scanning electron microscope. (2) Solvent insolubility of the coating layer A glass plate was prepared separately from the roller to be tested, and the coating liquid used for forming the coating layer of each roller was applied to the glass plate. The coating film was heated and cured to prepare a coating film sample. After immersing this glass plate in a solvent similar to that used for preparing the coating liquid at room temperature for 24 hours,
After drying, the weight of the coating film before and after immersion is measured, the solvent insolubility is calculated by the following equation, and the solvent insolubility of the coating layer of the roller is determined. Whether the solvent insolubility of the coating layer is 70% by weight or more It was confirmed. The solvent insolubility was 90% by weight or more in each case. Solvent insolubility = [(coating weight after immersion in solvent and drying) /
(Coating weight before immersion in solvent)] x 100 (% by weight)

(3) Measurement of Glass Transition Temperature of Coating Layer The glass transition temperature Tg (° C.) of the intermediate point was measured by differential scanning calorimetry (DSC) in accordance with the method for measuring the transition temperature of plastic according to JIS K7121. I asked. (4) Measurement of Dynamic Viscoelasticity of Coating Layer The dynamic elastic modulus E ′ [Log (dyn / cm ² )] and the loss tangent tan δ were measured by a dynamic viscoelasticity measuring apparatus rheograph SO.
It was measured by LID (Tokyo Seimitsu Co., Ltd.). The measurement conditions are
At room temperature (about 25 ° C) SET STRAIN: 0.5%, S
TATICSTRAIN: 1.0%, frequency: 5 Hz. (5) Surface roughness (Rz) For the roller to be tested, use a surface roughness meter Surfcom 590A.
(Manufactured by Tokyo Seimitsu Co., Ltd.) in a direction perpendicular to the axial direction (circumferential direction), measuring length 2.4 mm, measuring speed 0.3 mm /
The values measured at 300 points or more were averaged to obtain the JIS 10-point average roughness so that the cut-off wavelength was 0.8 mm and there was no deviation in the shaft direction and circumferential direction of the roller. (6) Resistance of coating layer (film resistance) A copper plate is prepared separately from the roller, and the coating liquid is applied to the copper plate by a bar coater using a coating film used for forming the coating layer of each roller. Then, the coating film was heated under the same conditions as those of each roller, and cured to form a uniform thin film. Resistivity meter R8
Using 340A (manufactured by Advantest), a voltage was applied so that the electric field strength became 5000 V / cm from the thickness of the formed thin film, and the volume resistivity was obtained. (7) Resistance of Roller A load of 500 g was applied to both ends of the roller to be tested, pressed against a copper plate, and a resistance value was measured by applying a voltage of 100 V using a resistivity meter R8340A (manufactured by Advantest). (8) Long-term operation Each toner carrier is attached to the developing unit shown in FIG. 2 as a developing roller, a developing bias is -400 V, a blade bias is -600 V, and a non-magnetic one-component negatively charged toner having an average particle diameter of 7 μm is used. An image was formed by reversal development while rotating at a linear speed of 50 mm / sec. Initially, it was confirmed that a good image appeared in a white background image and a black image on each toner carrier. As long-term operation conditions, 10,000 sheets of A4 size paper were printed in the horizontal direction in a 5% print pattern. (9) Toner Charge Amount After a long-term operation under the same apparatus conditions as described above, a uniform thin layer of toner formed on the surface of the developing roller was sucked and introduced into a Faraday gauge to measure the charge amount. At the same time, the weight of the sucked toner was also measured, and the toner charge per unit weight (μC / g) was determined. (10) Image evaluation After long-term operation, image evaluation was performed on a white background image and a black background image. The symbol x indicates that a large amount of image fog occurred in the white background image, and the symbol o indicates that the image was satisfactory without image fog. In the black background image, regarding the density reduction unevenness, the case where black density unevenness occurred was indicated by x, and the case where black density unevenness did not occur and was good was indicated by ○. In addition, Macbeth densitometer RD918 (Kollmorgen Instruments Corpora)
The density of the black was measured using the method described in the above section and was quantified.

Example 1 Propylene oxide and ethylene oxide were added to glycerin to give 100 parts (parts by weight, hereinafter the same) of a polyether polyol (OH value: 33 mgKOH / g) having a molecular weight of 5,000. 0 parts, nickel acetylacetonate 0.5 parts, dibutyltin dilaurate 0.01 parts and acetylene black 2.0 parts,
The mixture was mixed using a mixer to prepare a polyol composition.
After degassing by stirring this polyol composition under reduced pressure,
17.5 parts of urethane-modified MDI (diphenylmethane diisocyanate) was added, and the mixture was stirred for 2 minutes. The mixture was poured into a mold having a nickel-plated steel shaft placed therein and heated to 110 ° C. in advance, and cured at 110 ° C. for 2 hours. Then, a conductive elastic layer was formed on the outer periphery of the shaft to obtain a roller. The surface of the obtained roller was polished, and the surface was adjusted to a JIS 10-point average roughness of 10.5 μmRz. As described above, 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). Zemlac YC3372, an alkoxysilyl group-containing acrylic copolymer (manufactured by Kanegafuchi Chemical Co., Ltd., solid content: 50% by weight) as a binder resin, ZW806Z of organic esters as a dehydrating agent (Kanebuchi Chemical Industry Co., Ltd.), Organotin Zemrak BT1 as curing catalyst
20S (manufactured by Kanegafuchi Chemical Industry Co., Ltd.), Pastran TYPE-IV4410B (manufactured by Mitsui Mining & Smelting Co., Ltd.) having a tin oxide-based conductive layer formed on the surface of barium sulfate as a conductive powder, and MEK (methyl ethyl ketone) as a solvent.
Was used to prepare a coating liquid having the composition shown in Table 1 (the blending amount in Table 1 is shown in parts by weight, the same applies hereinafter). The roller is immersed in the coating liquid and pulled up.
FIG. 1 having a coating layer cured by crosslinking at 4 ° C. for 4 hours
The same roller-shaped toner carrier as in Example 1 was obtained.

Example 2 As a binder resin, Zemlac YC3372 (alkane silyl group-containing acrylic copolymer, manufactured by Kanegafuchi Chemical Co., Ltd., solid content: 50% by weight) and melamine resin Superpecamine L117 (Dainippon) Ink Chemical Industry Co., Ltd., solid content ratio 60% by weight) was used to prepare a coating liquid having the composition shown in Table 1, and the coating liquid was used to form a coating layer. Thus, a roller-shaped toner carrier was produced. Example 3 In Example 2, the conductive powder pastelan TYPE-IV was used.
4410B (Mitsui Metal Mining Co., Ltd.)
A coating liquid having the composition shown in the table was prepared, and a roller-shaped toner carrier was produced in the same manner as in Example 1 except that a coating layer was formed using this coating liquid. Example 4 In Example 3, the conductive powder was replaced with Pastoran TYPE-
Example 1 was repeated except that a coating solution having the composition shown in Table 1 was prepared in place of IV4350 (manufactured by Mitsui Mining & Smelting Co., Ltd.), which had higher resistance than IV4410B, and a coating layer was formed using this coating solution. In the same manner as in the above, a roller-shaped toner carrier was produced.

Example 5 As binder resins, Tuftec M1962, a polystyrene butadiene resin having a functional group (manufactured by Asahi Kasei Kogyo Co., Ltd.), and Super Beckamine L145, a melamine resin (manufactured by Dainippon Ink and Chemicals, Inc., solid content ratio) 60% by weight) and pastelan T as a conductive powder.
Using YPE-IV4410B (manufactured by Mitsui Mining & Smelting Co., Ltd.), P198 (manufactured by Dainippon Ink and Chemicals, Inc.) as a curing accelerator and Sulpers S3000 (manufactured by Zeneca Corporation) as a dispersant were added. A coating liquid having the composition shown in Table 1 was prepared using toluene as a solvent, and a roller-shaped toner carrier was produced in the same manner as in Example 1 except that a coating layer was formed using this coating liquid.

Example 6 In Example 5, a thermoplastic saturated copolyester resin, Elitel U, was used in place of Tuftec M1962.
Using E3400 (manufactured by Unitika Corporation), Solpers S24000 (manufactured by Zeneca Corporation) as a dispersant, MEK as a solvent, and preparing a coating solution having the composition shown in Table 1, and using this coating solution. A roller-shaped toner carrier was produced in the same manner as in Example 1 except that the coating layer was formed by the above method. Example 7 In Example 6, Dynal LR-258 which is a thermoplastic acrylic resin in place of Elitel UE3400 is used.
2 (manufactured by Mitsubishi Rayon Co., Ltd., solid content: 60% by weight), a mixed solvent of toluene and ethanol was used as a solvent to prepare a coating liquid having the composition shown in Table 1, and this coating liquid was used. A roller-shaped toner carrier was produced in the same manner as in Example 1 except that the coating layer was formed.

Comparative Example 1 In Example 1, the conductive powder Pastrun TYPE-IV was used.
Instead of 4410B, a coating liquid having the composition shown in Table 1 was prepared using carbon black # 220 (manufactured by Mikuni Dye Co., Ltd., solid content: 40% by weight) previously dispersed in a solvent and using toluene as a solvent. Then, a roller-shaped toner carrier was produced in the same manner as in Example 1 except that a coating layer was formed using this coating liquid. Comparative Example 2 In Example 2, conductive powder pastelan TYPE-IV
Instead of 4410B, a coating liquid having the composition shown in Table 1 was prepared using carbon black # 220 (manufactured by Mikuni Dye Co., Ltd., solid content: 40% by weight) previously dispersed in a solvent and using toluene as a solvent. Then, a roller-shaped toner carrier was produced in the same manner as in Example 1 except that a coating layer was formed using this coating liquid.

[0026]

[Table 1]

[0027]

[Table 2]

From the results shown in Table 1, it can be seen that the toner carriers of the examples show good toner chargeability without significant change in roller resistance even after long-term use, fog of white background images, and density of black images. It was confirmed that no deterioration unevenness was generated and a good image was stably obtained.

[0029]

According to the present invention, the developer carrier of the present invention exhibits good developer chargeability even when used for a long period of time. And is suitably used as a developer carrier of various image forming apparatuses.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a developer carrying member of the present invention.

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

[Explanation of symbols]

 1: toner carrier (developing roller) 2: shaft 3: conductive elastic layer 4: coating layer 5: toner applying roller 6: image forming body (photoreceptor) 7: toner 8: layered blade 9: transfer unit 10: Cleaning section 11: Cleaning blade

Continued on front page F term (reference) 2H077 AD06 EA13 EA14 EA15 EA16 FA01 FA13 FA22 FA25 3J103 AA02 AA14 AA23 AA51 BA41 FA12 FA30 GA02 GA52 GA57 GA58 GA60 HA03 HA12 HA20 HA41 HA45 HA47 HA53 4J002 AA011 AC011 AC031 AC06 BC1 BG031 CC181 CF001 CH041 CK021 CP031 DA026 DA036 DE096 DE106 DE136 DE186 DE196 DK006 EN136 EV186 EV256 FA086 FD116

Claims (12)

[Claims] An image forming member is formed by carrying a developer on the surface to form a thin film thereof, and in this state, contacting or approaching the image forming member and supplying the developer to the surface of the image forming member. In a developer carrier that forms a visible image on the surface,
Developer carrying member, the surface of the conductive elastic layer, the resin 100 parts by weight and 70 parts by weight of more than 200 parts by weight or less of 10 ⁰ -
A developer carrier having a coating layer made of a material containing a conductive powder of 10 ⁵ Ω · cm. 2. The method according to claim 1, wherein the conductive elastic layer is of Asker C type having a thickness of 40 to 40.
The developer carrier according to claim 1, wherein the developer carrier has a hardness of 80 °. 3. The developer carrier according to claim 1, wherein the conductive elastic layer is made of at least one rubber elastic material selected from butadiene rubber, ethylene propylene rubber, and urethane rubber. 4. The conductive elastic layer has a specific resistance of 10 ³ to 1
0 ¹⁰ Ω · cm and surface roughness of JIS 10 point average roughness of 1
The developer carrier according to claim 1, wherein the developer carrier is 5 μmRz or less. 5. The developer according to claim 1, wherein the resin constituting the coating layer is at least one selected from an acrylic resin, a styrene-butadiene resin, a polyester resin, an acryl-modified silicone resin, and a melamine resin. Carrier. 6. The developer carrier according to claim 1, wherein the resin constituting the coating layer has a glass transition point of 10 ° C. or less. 7. The coating layer having a dynamic elastic modulus E ′ of 10⁷~ 1
0^9.8dyn / cm ^TwoAnd the loss tangent tan δ is 0.7
The developer according to any one of claims 1 to 6, which is:
Carrier. 8. The developer carrier according to claim 1, wherein the coating layer has a thickness of 1 to 50 μm. 9. The developer carrier according to claim 1, wherein the coating layer has an insolubility in a solvent of 70% by weight or more. 10. The coating layer has a specific resistance of 10 ⁷ to 10 ^16.
The developer carrier according to any one of claims 1 to 9, wherein the developer carrier is Ω · cm. 11. The developer carrying member has a resistance of 10 ³ to 10 ^12.
Ω and surface roughness are 10 μm Rz in JIS 10 point average roughness
The developer carrier according to claim 1, wherein: 12. A developer carrier is mounted, and a developer is carried on the surface of the developer carrier to form a thin film, and the developer carrier is brought into contact with or close to the image forming body. By supplying a developer to the surface of the image forming body,
An image forming apparatus for forming a visible image on the surface of an image forming body, wherein the developer holding body according to claim 1 is used as the developer holding body.