JPH09325576A - Electrostatic charging member and electrostatic charging device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformalize an electric resistance of a surface layer, to improve an electrostatic chargeability, to suppress a sticking of a toner, etc., and to improve a durability of an electrostatic charge member by providing the surface layer consisting of a water based polyurethane resin formed by imparting a hydrophilic group to a polyurethane resin at a periphery of an intermediate layer. SOLUTION: This charge member is formed in roller shape for example, and composed of a conductive supporting body 101 having a shape of a core metal, the intermediate layer (elastic layer) 102 provided at the periphery of the conductive supporting body 101 and the surface layer 103 formed on the outer periphery of the elastic layer 102. In this case, the water based polyurethane resin formed by imparting the hydrophilic group to the polyurethane resin is used as the surface layer 103 on the surface of the outer periphery of the elastic layer 102. In this way, an excellent nonadherence and wear resistance against toner is imparted. The water based polyurethane resin formed in such a way hardly contaminates the surface of an org. photoreceptor since a self-dispersion type polyurethane water dispersion which does not use an emulsion, etc., is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member used in an electrophotographic apparatus and a charging apparatus using the same.
More specifically, it relates to a charging member having an intermediate layer around a conductive support and a charging device using the charging member.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus of an electrophotographic apparatus, a corona discharger has been widely used as a charging method for uniformly charging the entire surface of a photoconductor. Although this corona discharger is effective as a means for uniformly charging the photoconductor to a certain constant potential, it requires a high-voltage power source, and it produces ozone due to discharge, and a large amount of ozone is generated. If it occurs, it not only adversely affects the environment, but also has the disadvantage that ozone deteriorates the charging member and the photoconductor.

On the other hand, a contact roller charging system in which a charging roller (charging member) is brought into contact with a photosensitive member and a voltage is applied while being driven to rotate to charge the surface of the photosensitive member has been put into practical use. This method has the advantages of lowering the voltage of the power supply and less ozone generation, but it is inferior to the corona discharge method in terms of charging uniformity.

In order to improve the uniformity of charging, for example, in the "contact charging method" disclosed in Japanese Patent Laid-Open No. 63-149668, the charging start voltage is doubled when a DC voltage is applied. It is disclosed that the uniformity of charging can be considerably improved by superimposing the AC voltage having the above peak-to-peak voltage. However, in the contact charging method of charging by applying a voltage in which the AC voltage and the DC voltage are superposed, the vibration of the machine generated by the superposed AC voltage gives an unpleasant environment as a charging sound, and ，
The consumption of a large amount of AC voltage causes a disadvantage that the reduction of ozone generation is impaired.

Although these disadvantages are solved by applying only a DC voltage to the charging device to carry out charging,
The problem remains that it is difficult to obtain uniform charging with only a DC voltage. Therefore, according to JP-A-5-341627, the uniformity of charging and the withstand voltage are improved by using epichlorohydrin rubber, which is semiconductive by the rubber itself, in the elastic layer of the charging member (charging roller). In addition, the ozone generation amount is reduced to 1/30 to 1/40 of AC superposition.

As a conventional charging member, Japanese Patent Laid-Open No. 7-
No. 72710, "Charging Member and Charging Device". This charging member has a sponge layer (elastic layer) of the charging member provided with a functional layer (surface layer) containing a water-based polymer compound, and is charged by the functional layer containing the water-based polymer compound. Smooth the surface of the member,
The object to be charged (photoconductor) is favorably charged and the charging noise is reduced.

[0007]

However, according to the above-mentioned conventional charging member, although the non-adhesive surface layer is formed on the semiconductive elastic layer, it is used as a charger of a copying machine. If so, toner, paper dust, etc. will adhere to the surface of the charging member. As a result, the electric resistance of the charging member is increased, the charging performance is deteriorated, and charging unevenness occurs, which is a problem in terms of durability. That is, residual toner particles that have slipped through the cleaning unit and remain on the photoconductor adhere to the surface of the charging member that is in contact with the photoconductor, and have the above-described adverse effect.

According to Japanese Patent Laid-Open No. 7-72710, a functional layer containing a water-based polymer compound smoothes the surface of a charging member so that an object to be charged (photoreceptor) can be favorably charged. However, the functional layer is not composed only of a water-based polymer compound, and conductive particles (conductive filler) are doped to adjust the electrical resistance of the functional layer (surface layer) to conduct a conductive treatment. When the surface of the functional layer is enlarged, the difference in electrical resistance between the part where the conductive particles are dispersed and the part where the aqueous polymer compound is present is locally different. Therefore, there is a problem that the charged body (photoreceptor) cannot be uniformly charged.

The water-based polyurethane resin used as the water-based polymer compound is formed by forcibly emulsifying the polyurethane resin with a surfactant and by imparting a hydrophilic group to the polyurethane resin. When two types of water-based polyurethane resin, that is, water-based polyurethane resin, are used and used as the surface layer, the former has a relatively high resistance and the latter has a relatively low resistance. However, according to Japanese Patent Application Laid-Open No. 7-72710, an aqueous polyurethane resin forcibly emulsified with a surfactant is used, as is apparent from the fact that conductive particles (conductive filler) are doped and conductive treatment is performed. Therefore, when used for a long time, the surfactant (emulsifier / dispersant) gradually leaches out to the surface of the surface layer, and the leached emulsifier or dispersant contaminates the photoreceptor surface. There was a point. When a surface layer formed using this type of water-based polyurethane resin is used in an image forming apparatus, there is a problem that image deterioration occurs.

Further, according to the above-mentioned conventional charging member using the epichlorohydrin rubber in the elastic layer, the electric resistance of the epichlorohydrin rubber has very little humidity dependence, but has large temperature dependence, especially in a low temperature range of use environment. In case of
There was a problem that the electric resistance increased and the charging potential decreased.

This problem will be described in detail.
From 0% normal temperature and humidity (hereinafter referred to as M environment) to 30 ° C, 90
There is very little fluctuation in electric resistance over high temperature and high humidity (hereinafter referred to as H environment) of 10%, but 10 ° C, 15% from M environment.
The fluctuation in the electric resistance during low temperature and low humidity (hereinafter referred to as L environment) increases by about 1 order, and as a result, the charging potential in the L environment decreases.

As a countermeasure for the above, it is necessary to detect the temperature of the roller surface and correct the charging potential with an applied voltage corresponding to the temperature, but this method has a problem of increasing the cost of the member. .

The present invention has been made in view of the above problems, and an object thereof is to make the electric resistance of the surface layer uniform and improve the charging performance.

The present invention has been made in view of the above problems, and suppresses the adhesion of toner or the like to the surface of the charging member to improve the durability of the charging member and increase the cost. It is an object of the present invention to prevent a decrease in the charging potential in the L environment without causing an electric shock.

[0015]

In order to achieve the above object, a charging member according to claim 1 is a charging member having an intermediate layer around a conductive support, wherein a polyurethane is provided around the intermediate layer. A surface layer made of a water-based polyurethane resin formed by giving a hydrophilic group to a resin is provided.

In the charging member according to the second aspect, the intermediate layer is made of an elastic material.

In the charging member according to the third aspect, the intermediate layer is made of a medium resistance material.

Further, in the charging member according to the fourth aspect, the surface layer does not contain a surfactant.

The charging member according to a fifth aspect is a charging member having an intermediate layer around a conductive support, wherein the intermediate layer is epichlorohydrin-ethylene oxide-
It is composed of an allyl glycidyl ether terpolymer rubber.

Further, in the charging member according to claim 6, the composition ratio (mol%) of the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer rubber is 4
It is in the range of 0/58/2 to 60/32/8.

According to a seventh aspect of the present invention, there is provided a charging device, wherein the charging member according to any one of the first to sixth aspects is used, and a voltage applied to the conductive support in a state where the charging member is in contact with the image carrier. The DC voltage is used as.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, regarding a charging member according to the present invention and a charging device using the same, the shape and configuration example of the charging member according to the present invention. A detailed description will be given with reference to the drawings.

Shape and Configuration Example of Charging Member of the Present Invention First, a shape example of the charging member of the present invention will be described. The charging member of the present invention is, for example, in the shape of a roller as shown in FIG.
An elastic layer (intermediate layer of the present invention) 102 provided around the conductive support 101, and a surface layer 103 formed on the outer peripheral surface of the elastic layer 102.

Alternatively, the charging member of the present invention comprises a conductive support 101 in the form of a flat plate as shown in FIG. 2, an elastic layer 102 provided around the conductive support 101, and an elastic layer 102. It may be composed of the surface layer 103 formed on the outer peripheral surface, but a roller shape is preferable in terms of uniform charging.

Further, the charging member of the present invention, as shown in FIG. 3, is a conductive support member 10 having a pair of parallel axes.
1, an endless belt-shaped elastic layer 102, and an elastic layer 1
02, and the surface layer 103 formed on the outer peripheral surface.

It should be noted that in FIGS. 1 to 3, an adhesive layer for improving the adhesiveness between the conductive support 101, the elastic layer 102 and the surface layer 103 may be provided. For example,
In the case of a roller shape, the conductive support 101 may be treated with a conductive primer such as synthetic rubber containing a conductive substance such as carbon black.

As the conductive support 101, a metal such as iron, stainless steel or aluminum, a conductive resin such as a carbon black dispersed resin or a metal particle dispersed resin can be used, and the shape thereof is rod-like, plate-like or the like. Is used.

The elastic layer 102 has an electric resistance of 10 ⁷ to
Good results are obtained in the range of 10 ⁹ Ω · cm.
Therefore, polar rubbers such as epichlorohydrin rubber, nitrile rubber, urethane rubber, chloroprene rubber, and acrylic rubber can be used as the material, but among them, the electric resistance of the rubber itself is relatively small, and further the environment resistance is high. It uses epichlorohydrin rubber because of its good properties.

Further, epichlorohydrin rubber (abbreviation: E)
CO) is an ECO homopolymer, a copolymer of ECO and ethylene oxide (abbreviation: EO), a copolymer of ECO and allyl glycidyl ether (abbreviation: AGE), ECO
There is a terpolymer of EO and AGE (abbreviation: GECO). Among them, GECO is preferable because of its relatively low electric resistance and good environmental resistance.

In the GECO system, the composition ratio (mol%) of each unit is shown by the hatched portion in FIG.
It was found that those having a ratio of 40/58/2 to 60/32/8 can reduce the increase in electric resistance under the L environment.

FIG. 4 is a diagram showing the relationship between the AGE content (mol%) and the ECO content (mol%), which are the composition ratios of the respective units. Further, FIG. 5 shows the relationship between the electric resistance and the three environments (L environment, M environment, H environment) under each composition ratio shown in FIG.

The layer thickness of the elastic layer 102 is 0.5 to 1
Good results are obtained in the range of 0 mm. The reason is that when the thickness of the elastic layer 102 is less than 0.5 mm, the organic photoconductor (abbreviation: OPC) causes dielectric breakdown and charging becomes unstable, and there is a pinhole in the OPC. The current concentrates on that portion, and the leakage easily occurs, and as a result, horizontal stripes appear on the image. Also,
This is because if the layer thickness of the elastic layer 102 is thicker than 10 mm, the charging efficiency is lowered and it becomes necessary to apply a higher voltage, and as a result, the ozone generation amount is increased.

On the basis of the above points, by using the water-based polyurethane resin formed by imparting a hydrophilic group to the polyurethane resin as the surface layer 103 on the outer peripheral surface of the elastic layer 102, it is excellent for toner and the like. It has been found that it can have non-adhesiveness and abrasion resistance and is effective as a means for improving the durability of the charging member without contaminating the OPC.

The water-based polyurethane resin used for the surface layer 103 is a water-soluble type or self-dispersing type by imparting some hydrophilic groups (hydrophilic groups or hydrophilic segments) to the urethane elastomer of the crosslinked structure. Therefore, it does not contain a surfactant. Further, this resin is classified into a reactive type and a non-reactive type depending on the presence or absence of reactivity. The reactive type is a type that has reactivity such as a blocked isocyanate group in the structure, regenerates a free isocyanate group by post-treatment such as heating, and causes a crosslinking reaction. On the other hand, since the non-reactive type does not have a reactive group in the structure, a strong coating can be formed by either air drying or heat drying. These resins are marketed by Dai-ichi Kogyo Seiyaku Co., Ltd. under the names of "Elastron" series as a reactive type and "Superflex" series as a non-reactive type.

In addition, conventional aqueous resin emulsions and latexes such as vinyl acetate emulsion, ethylene vinyl acetate emulsion, vinyl chloride emulsion, acrylic emulsion, butadiene rubber latex, isoprene rubber latex, styrene-butadiene rubber latex, chloroprene rubber latex, etc. Since the emulsifier and the dispersant are contained therein, when the surface layer 103 is formed by using these water-based resin emulsion or latex, the emulsifier and the dispersant ooze out to the surface of the surface layer 103, The leached emulsifier and dispersant contaminate the OPC surface. As a result, when the surface layer 103 formed by using a water-based resin emulsion or latex is used in an image forming apparatus, there is a problem that image deterioration occurs. However, by adding a hydrophilic group to the polyurethane resin used in the present invention, Since the formed water-based polyurethane resin is a self-dispersion type polyurethane water dispersion that does not use an emulsifier, etc.
Does not contaminate the surface.

Configuration Example of Charging Device of the Present Invention Next, the configuration of the charging device of the present invention using the above charging member will be described with reference to FIG. In the figure, 601
Indicates the charging member of the present invention, and here, the roller-shaped charging member shown in FIG. 1 is used. Reference numeral 602 indicates a DC power supply for applying a DC voltage to the core of the charging member 601. The charging member 601 and the DC power source 602 constitute the charging device of the present invention.

FIG. 6 shows an example in which the charging device of the present invention is applied to an electrophotographic device. In this electrophotographic device, the primary charging member 6 is provided on the peripheral surface of a drum-shaped electrophotographic photosensitive member 603.
01, image exposure device (not shown), developing unit 604,
A transfer charging device 605, a cleaning device 606, and a pre-exposure device (not shown) are arranged. In the figure, reference numeral 607 denotes exposure light emitted from the image exposure device, and 60
Reference numeral 8 denotes pre-exposure light of the pre-exposure device, and 609 denotes a transfer target member such as paper.

For example, an electrophotographic photosensitive member 60 such as OPC
Primary charging member (charging member 60) disposed in contact with
A voltage (for example, −
1400 V) is applied to charge the surface of the electrophotographic photosensitive member 603, and an image on a document is imagewise exposed to the electrophotographic photosensitive member 603 by an image exposure device to form an electrostatic latent image.

Next, the developer in the developing unit 604 is adhered to the electrophotographic photosensitive member 603 to develop the electrostatic latent image on the electrophotographic photosensitive member 603, and further to develop on the electrophotographic photosensitive member 603. The transfer charging device 605 transfers the agent to a transfer target member 609 such as paper, and the cleaning device 606 collects the developer remaining on the electrophotographic photoreceptor 603 without being transferred to the paper at the time of transfer. Further, when residual charge remains on the electrophotographic photosensitive member 603, it is better to remove the residual charge on the electrophotographic photosensitive member 603 by a pre-exposure device before performing the primary charging by the charging member 601.

The process leading to the present invention has been described above by describing the shape and configuration example of the charging member of the present invention and the configuration example of the charging device of the present invention. However, uniform charging is achieved only by applying a DC voltage. The charging uniformity of the charging member 601 of the present invention, which is to be obtained, is naturally different from that of a conventional charging roller (for example, Japanese Patent Laid-Open Nos. 64-73364 and 64-73367) which is left to superimpose AC voltage. The electrical characteristics (R, C) and the layer structure of the rollers are greatly different. That is, the AC voltage superposition type has the elastic layer 1
02 (rubber in which conductive particles such as carbon black are dispersed in rubber) and a surface resistance layer, the surface resistance layer functions as a capacitor, so that the electrostatic capacity is large and the uniform effect of the charging potential due to the AC voltage superposition is obtained. large.

On the other hand, in the type only applying the DC voltage of the present invention, the roller layer acts as a resistor (that is,
Since the electrostatic capacity is small), superimposing an AC voltage hardly contributes to uniform charging.

Embodiments 1 to 5 Hereinafter, regarding the charging member of the present invention, [Embodiment 1], [Embodiment 2], [Embodiment 3], [Embodiment 4], [Embodiment 5]
Will be described in this order with reference to the drawings.

[Embodiment 1] In Embodiment 1, the charging member is prepared by the following method. First, as the conductive support 101, a φ8 mm stainless steel core is used. Next, the elastic layer 102 is made with the following composition. GECO epichlorohydrin (prototype 1 described later) 100 parts by weight Light calcium carbonate 30 parts by weight Sub: Product name GT (manufactured by Tenma Sub Chemical Co., Ltd.) 10 parts by weight Zinc white 5 parts by weight Stearic acid 0.5 parts by weight Vulcanization accelerator: product Name Nox Cellar TT (Ouchi Shinko Kagaku) 1.0 parts by weight 〃: Brand name Nox Cellar DM (Ouchi Shinko Kagaku) 1.5 parts by weight 〃: Brand name Barnock R (Ouchi Shinko Kagaku) 1.0 parts by weight Part Vulcanizing agent: Trade name Salfax PMC (Tsurumi Chemical Co., Ltd.) 0.25 parts by weight

After kneading the above-mentioned compound to form a compound having a uniform composition, it was molded on a φ8 mm stainless steel core metal (conductive support 101) by a molding method (primary vulcanization: 150 ° C. × 15).
Min, secondary vulcanization: 155 ° C. × 7 hours), and a roller-shaped elastic layer 102 having an outer diameter of 14 mm was provided.

The composition ratio of this GECO type epichlorohydrin (trial 1) was ECO: 40 mol%, EO: 5
3 mol%, AGE: 7 mol%, and the relationship between the AGE content (mol%) and the ECO content (mol%) is shown in a of FIG. The electric resistance of this elastic roller under each environment is shown in FIG.

The electric resistance of the roller was measured by leaving the roller in each environment for 16 hours and then winding a copper foil tape (made by Scotch No. 1181: 3M) having a width of 25.4 mm around the circumference of the roller. Then, a DC voltage of 1000 V was applied between the roller core metal and the electrode, and the current value 1 minute after that was measured to obtain the resistance value between the core metal and the electrode.

Next, the surface layer 103 was formed on the above-prepared elastic roller as follows. First, as a water-based polyurethane resin, a non-reactive type (Superflex 107:
100 parts by weight (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was diluted with 100 parts by weight of water. This solution was applied onto the elastic roller by dip coating, dried at 100 ° C. for 15 minutes, and the film thickness after drying was 10 μm.
The surface layer 103 was provided. Table 1 shows the results of measuring the electrical resistance of the charging roller (charging member) having the surface layer 103 formed on the elastic roller in the M environment in this way.

The charging roller (charging member) manufactured as described above is a regular developing type copying machine FT5500 (manufactured by Ricoh).
It was attached instead of the primary corona charger, and was brought into contact with the surface of the OPC drum to be driven to rotate. A DC voltage of -1,400 V was applied as the primary charging voltage, and 5000 sheets were continuously operated under the M environment and the L environment, and the potential of the OPC dark potential was measured, and the contamination state of the charging roller surface and the image quality were measured and evaluated.

The results of the above measurements and evaluations are shown in Table 1.
The state of contamination of toner on the surface of the charging roller was evaluated according to the following criteria. Double circle: A small amount of toner adheres, but you can easily wipe off the adhered matter on the roller surface with a cloth. ◯: A small amount of toner remains on the roller surface after wiping. Δ: The film cannot be completely wiped off, and a thin film such as toner remains on the roller surface. X: Toner or the like is strongly adhered to the roller surface.

[0050]

[Table 1]

Example 2 Instead of the GECO type epichlorohydrin (trial 1) containing the elastic layer 102 of Example 1, a GECO type epichlorohydrin (Epichromer C) was used.
G: manufactured by Daiso), an elastic roller was prepared in the same manner.

The composition ratio of this GECO type epichlorohydrin (epichromer CG) was ECO: 52 mol%, EO: 41 mol%, AGE: 7 mol%.
The relationship between the E content (mol%) and the ECO content (mol%) is shown in b of FIG. The electric resistance of this elastic roller under each environment is shown in b of FIG.

Next, the surface layer 103 was formed on the above-prepared elastic roller as follows. First, as an aqueous polyurethane resin, a resin comprising 100 parts by weight of a reactive type (Elastron H-3: manufactured by Dai-ichi Kogyo Seiyaku), 2 parts by weight of a catalyst (Elastron Catalyst 64: manufactured by Dai-ichi Kogyo Seiyaku), and 100 parts by weight of water. The solution was made a weakly alkaline base with a sodium hydrogencarbonate aqueous solution (2 wt%) as a pH adjuster.

This liquid is dip coated on the elastic roller,
Surface layer 10 having a film thickness of 8 μm after drying at 150 ° C. for 10 minutes
3 were provided.

Table 1 shows the electric resistance value of the charging roller (charging member) in which the surface layer 103 is formed on the elastic roller in the M environment, and the evaluation result by the actual machine performed in the same manner as in Example 1. .

Example 3 Instead of the GECO type epichlorohydrin (trial 1) containing the elastic layer 102 of Example 1, a GECO type epichlorohydrin (epichromer CG) was used.
102: manufactured by Daiso Co., Ltd., and an elastic roller was similarly prepared.

The composition ratio of this GECO type epichlorohydrin (epichromer CG102) was ECO: 40.
Mol%, EO: 56 mol%, AGE: 4 mol%,
The relationship between the AGE content (mol%) and the ECO content (mol%) is shown in c of FIG. The electric resistance of this elastic roller under each environment is shown in FIG.

Next, the surface layer 103 was formed on the elastic roller prepared above as follows. First, a surface layer 103 having a film thickness of 7 μm was provided with the same non-reactive water-based polyurethane resin (Superflex 107) paint as in Example 1.

Table 1 shows the electric resistance value of the charging roller (charging member) having the surface layer 103 formed on the elastic roller in the M environment and the evaluation result by the actual machine performed in the same manner as in Example 1.

Example 4 Instead of the GECO type epichlorohydrin (trial 1) containing the elastic layer 102 of Example 1, a GECO type epichlorohydrin (Zecron 210) was used.
An elastic roller was prepared in the same manner except that it was manufactured by Nippon Zeon.

The composition ratio of this GECO type epichlorohydrin (Zeklon 2101) is ECO: 50 mol%, EO: 47.5 mol%, AGE: 2.5 mol%, and the AGE content (mol%) and ECO The relationship with the content (mol%) is shown in d of FIG. The electric resistance of this elastic roller under each environment is shown in d of FIG.

Next, the surface layer 103 was formed on the above-prepared elastic roller as follows. First, a surface layer 103 having a film thickness of 20 μm was provided with the same non-reactive water-based polyurethane resin (Superflex 107) paint as in Example 1.

Table 1 shows the electric resistance value of the charging roller in which the surface layer 103 is formed on the elastic roller in the M environment and the evaluation result by the actual machine performed in the same manner as in Example 1.

[Embodiment 5] Instead of the GECO-based epichlorohydrin (Prototype 1) containing the elastic layer 102 of Example 1, a GECO-based epichlorohydrin (epichromer CG) was used.
107: manufactured by Daiso), an elastic roller was prepared in the same manner.

The composition ratio of this GECO type epichlorohydrin (epichromer CG107) was ECO: 56.
Mol%, EO: 41 mol%, AGE: 3 mol%,
The relationship between the AGE content (mol%) and the ECO content (mol%) is shown in e of FIG. The electric resistance of this elastic roller under each environment is shown in FIG.

Next, the surface layer 103 was formed on the above-prepared elastic roller as follows. First, the same reactive water-based polyurethane resin as in Example 2 (Elastron H-
3) A surface layer 103 having a film thickness of 4 μm was provided with a paint.

Table 1 shows the electric resistance value of the charging roller in which the surface layer 103 is formed on the elastic roller in the M environment and the evaluation result by the actual machine performed in the same manner as in Example 1.

COMPARATIVE EXAMPLE 1 Here, Comparative Example 1 is used as a comparative example.
Was created as follows. Table 1 shows the results of evaluation performed in the same manner as in Example 1 by using the same elastic roller as in Example 1 as the charging roller without forming the surface layer 103 on the outer peripheral surface thereof.

[Comparative Example 2] Here, Comparative Example 2 is used as a comparative example.
Was created as follows. Elastic layer 102 of Example 1
An elastic roller was prepared in the same manner except that GECO-based epichlorohydrin (Prototype 2 described later) was used in place of the compounded GECO-based epichlorohydrin (Prototype 1).

The composition ratio of this GECO type epichlorohydrin (prototype 2) was ECO: 45 mol%, EO: 4
6 mol%, AGE: 9 mol%, and the relationship between the AGE content (mol%) and the ECO content (mol%) is shown in f of FIG. The electric resistance of this elastic roller under each environment is shown in f of FIG.

A surface layer 103 having a film thickness of 10 μm was formed on the elastic roller prepared as described above in the same manner as in Example 1.

The electric resistance value of this charging roller in the M environment and the evaluation by the actual machine were performed in the same manner as in Example 1, and the evaluation results are shown in Table 1.

COMPARATIVE EXAMPLE 3 Here, Comparative Example 3 is used as a comparative example.
Was created as follows. Elastic layer 102 of Example 1
Instead of the compounded GECO-based epichlorohydrin (Prototype 1), GECO-based epichlorohydrin (Zecron 310
0: manufactured by Zeon Corporation), an elastic roller was prepared in the same manner.

The composition ratio of this GECO type epichlorohydrin (Zeklon 3100) was ECO: 65 mol%, EO: 27 mol%, AGE: 8 mol%.
The relationship between the E content (mol%) and the ECO content (mol%) is shown in g of FIG. The electric resistance of this elastic roller under each environment is shown in FIG.

A surface layer 103 having a film thickness of 15 μm was formed on the elastic roller prepared as described above in the same manner as in Example 1.

The electrical resistance value of this charging roller in the M environment and the evaluation by the actual machine were performed in the same manner as in Example 1, and the evaluation results are shown in Table 1.

[Comparative Example 4] Here, Comparative Example 4 is used as a comparative example.
Was created as follows. Elastic layer 102 of Example 1
An elastic roller was prepared in the same manner except that GECO-based epichlorohydrin (Prototype 3 described later) was used instead of the GECO-based epichlorohydrin (Prototype 1).

The composition ratio of this GECO type epichlorohydrin (trial 3) was ECO: 35 mol%, EO: 6
0 mol%, AGE: 5 mol%, and the relationship between the AGE content (mol%) and the ECO content (mol%) is shown in h of FIG. The electric resistance of this elastic roller under each environment is shown in h of FIG.

A surface layer 103 having a film thickness of 12 μm was formed on the elastic roller prepared as described above in the same manner as in Example 1.

The electrical resistance value of this charging roller in the M environment and the evaluation by the actual machine were performed in the same manner as in Example 1, and the evaluation results are shown in Table 1.

COMPARATIVE EXAMPLE 5 Here, Comparative Example 5 is used as a comparative example.
Was created as follows. Elastic layer 102 of Example 1
Instead of the compounded GECO-based epichlorohydrin (Prototype 1), GECO-based epichlorohydrin (Epichromer C
G104: manufactured by Daiso), an elastic roller was prepared in the same manner.

The composition ratio of this GECO type epichlorohydrin (epichromer CG104) was ECO: 63.
Mol%, EO: 34.5 mol%, AGE: 2.5 mol%
And AGE content (mol%) and ECO content (mol%)
The relationship with is shown in i of FIG. The electric resistance of this elastic roller under each environment is shown in i of FIG.

A surface layer 103 having a film thickness of 8 μm was formed on the elastic roller prepared as described above in the same manner as in Example 1.

The electric resistance value of this charging roller in the M environment and the evaluation by the actual machine were performed in the same manner as in Example 1, and the evaluation results are shown in Table 1.

[Comparative Example 6] Here, Comparative Example 6 is used as a comparative example.
Was created as follows. Elastic layer 102 of Example 1
An elastic roller was prepared in the same manner except that GECO epichlorohydrin (Prototype 4 described later) was used in place of the compounded GECO epichlorohydrin (Prototype 1).

The composition ratio of this GECO type epichlorohydrin (prototype 4) was ECO: 45 mol%, EO: 5
4 mol%, AGE: 1 mol%, and the relationship between the AGE content (mol%) and the ECO content (mol%) is shown in j of FIG. The electric resistance of this elastic roller under each environment is shown in j of FIG.

The surface layer 103 having a film thickness of 7 μm was formed on the elastic roller prepared as described above in the same manner as in Example 1.

The electrical resistance value of this charging roller in the M environment and the evaluation by the actual machine were performed in the same manner as in Example 1, and the evaluation results are shown in Table 1.

As described above, as is clear from Examples 1 to 5 and Comparative Examples 1 to 6, the charging member of the present invention can suppress the adhesion of toner and the like to the charging roller,
Furthermore, since it is possible to prevent the charging potential from decreasing even under the L environment, the initial image quality can be maintained for a long period of time.

Further, since the uniform charging can be performed by applying only the DC voltage, the cost of the charging device can be reduced.

[0091]

As described above, according to the charging member of the present invention (claims 1 to 4), in the charging member having the intermediate layer around the conductive support, the polyurethane is formed around the intermediate layer. Since the surface layer made of water-based polyurethane resin formed by giving a hydrophilic group to the resin is provided, it is not necessary to do conductive treatment by doping conductive particles, the electric resistance of the surface layer is made uniform, and the charging performance is improved. Can be achieved. Further, even when used for a long period of time, the surfactant (emulsifier / dispersant) does not seep out to the surface of the surface layer, so that the initial image quality can be maintained for a long period of time.

The charging member of the present invention (claims 5 and 6)
According to the method, in the charging member having the intermediate layer around the conductive support, the intermediate layer is made of epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer rubber. Resistance fluctuations are reduced, and the charged potential on the photoconductor is
Alternatively, since the charging potential is stable even when the first copy is made in the morning, good output image quality can be maintained, and the cost of the charging device can be reduced.

According to the charging device of the present invention (Claim 7), the voltage applied to the conductive support in the state where the charging member is in contact with the image carrier is a direct current voltage, so that ozone is generated. It is possible to reduce the amount and cost of the power supply, and to provide an inexpensive charging device.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a shape and a configuration example of a charging member of the present invention.

FIG. 2 is an explanatory diagram showing a shape and a configuration example of a charging member of the present invention.

FIG. 3 is an explanatory diagram showing a shape and a configuration example of a charging member of the present invention.

FIG. 4 is an explanatory diagram showing the relationship between the AGE content (mol%) and the ECO content (mol%), which are the composition ratios of each unit.

FIG. 5: Three environments (L environment, M environment, H) for each composition ratio
It is explanatory drawing which shows the relationship between (under environment) and electric resistance.

FIG. 6 is an explanatory diagram showing an example in which the charging device of the present invention is applied to an electrophotographic apparatus.

[Explanation of symbols]

 101 Conductive Support 102 Elastic Layer 103 Surface Layer 601 Charging Member 602 DC Power Supply

Claims (7)

[Claims] 1. A charging member having an intermediate layer around a conductive support, wherein a surface layer made of a water-based polyurethane resin formed by imparting a hydrophilic group to a polyurethane resin is provided around the intermediate layer. Characteristic charging member. 2. The charging member according to claim 1, wherein the intermediate layer is made of an elastic material. 3. The charging member according to claim 1, wherein the intermediate layer is made of a medium resistance material. 4. The charging member according to claim 1, wherein the surface layer does not contain a surfactant. 5. A charging member having an intermediate layer around a conductive support, wherein the intermediate layer comprises epichlorohydrin-
A charging member comprising an ethylene oxide-allyl glycidyl ether terpolymer rubber. 6. The composition ratio (mol%) of the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer rubber is in the range of 40/58/2 to 60/32/8. 5. The charging member according to item 5. 7. The charging member according to claim 1, wherein a DC voltage is used as a voltage applied to the conductive support in a state where the charging member is in contact with an image carrier. Charging device.