JPH11149201A - Manufacture of charging member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a changing member superior in releasability from a photosensitive body drum and toner, capable of preventing the leak of a charged potential against a photosensitive defect, and stably and uniformly charging. SOLUTION: A semiconductive elastic layer 22 comprising epichlorohydrin rubber is formed on a stainless steel-made conductive support body (core metal) 21. This roller is set in an ultraviolet radiation irradiation device, and an ultraviolet radiation is irradiated onto the semiconductive layer 22 from an ultraviolet lamp (a high pressure mercury lamp) to reform its surface layer, to form a protection layer 23 and form a charged roller 20. The output of the used ultraviolet lamp is 80 W/cm, a rated power is 2000 W, a wave length is 200 to 450 nm, and an irradiation time is three minutes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a charging member (such as a charging roller) for performing a charging process on a photosensitive member in an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art A charging roller type image forming apparatus 110 will be described with reference to FIG. The charging roller is the most general charging member used in the image forming apparatus. In FIG. 5, reference numeral 101 denotes a photosensitive drum on which an electrostatic latent image is formed, and reference numeral 102 denotes a charging roller that contacts the photosensitive drum 101 and performs a charging process. Reference numeral 103 denotes exposure of laser light or light reflected from a document. Reference numeral 104 denotes a developing roller for attaching toner to the electrostatic latent image on the photoreceptor 101;
Reference numeral 05 denotes a power pack for applying a voltage to the charging roller 102, reference numeral 106 denotes a transfer roller, and reference numeral 107 denotes a recording sheet conveyed from a sheet feeding unit. The transfer roller 106 transfers the toner image on the photosensitive drum 101 to the recording paper 107. Reference numeral 108 denotes a cleaning device for the surface of the photoconductor drum, and reference numeral 109 denotes a surface voltmeter for measuring the surface potential of the photoconductor drum 101. In FIG. 5, functional units normally required in other electrophotographic processes are not shown.

The image forming apparatus 11 configured as described above
The basic image forming operation at 0 will be described. By applying a voltage from a power pack 105 to a charging roller 102 which is in contact with the photosensitive drum 101, the surface of the photosensitive drum 101 is uniformly charged to a high potential. Immediately thereafter, when image light (exposure 103) is irradiated on the surface of the photosensitive drum 101, the irradiated portion has a lower potential. Since the image light has a light amount distribution corresponding to the black / white of the image, the potential distribution corresponding to the recorded image, that is, an electrostatic latent image is formed on the surface of the photosensitive drum 101 by the irradiation of the image light.

The portion where the electrostatic latent image is formed is the developing roller 1
After passing through 04, toner adheres according to the level of the potential, and a toner image is formed by visualizing the electrostatic latent image.
The recording paper 107 is conveyed to the portion where the toner image is formed by a registration roller (not shown) at a predetermined timing, and overlaps the toner image. This toner image is transferred to a transfer roller.
After being transferred to the recording paper 107 by the roller 106, the recording paper 107 is separated from the photosensitive drum 101. The separated recording paper is conveyed through a conveyance path, is fixed by heat and pressure by a fixing unit (not shown), and is discharged outside the apparatus. After the transfer, the photosensitive drum 10
The surface of 1 is cleaned by a cleaning device 108, and residual charges are erased by a quenching lamp (not shown), so that the surface is prepared for the next image forming process.

[0005] The mechanism of charging the surface of the photosensitive drum 101 by the charging roller 102 is as follows.
2. It is known that the discharge is in accordance with Paschen's law in a minute space between the photosensitive drums 101. The contact-type charging roller 102 abuts on the photosensitive drum 101 made of a metal substrate with a predetermined pressing force, and the photosensitive drum 101
When the charging roller 102 does not have sufficient flexibility, a floating occurs between the charging roller 102 and the photosensitive drum 101 in a slight depression on the surface. Because of the variation, charging failure occurs.

Therefore, in the charging roller 102, as shown in FIG. 6, a semiconductive elastic layer 20 is formed on a conductive support 201.
By providing 2, the floating of the photosensitive drum 101 is prevented.

A rubber material is often used for the semiconductive elastic layer 202. Generally, since the rubber material contains an oil therein for imparting flexibility, the photosensitive drum 1
There is a problem that the oil oozes out with the pressing force of 01.
As a method for eliminating this, as shown in FIG. 6, a protective layer 20 having a barrier function is formed on a semiconductive elastic layer 202.
Those that form No. 3 have been proposed. This protective layer 203
By using an appropriate resin material, a barrier effect can be obtained. However, as described above, since the charging roller needs flexibility, the protective layer 203 needs to sufficiently follow the deformation of the semiconductive elastic layer 202.

The protective layer 203 is required to have good mechanical strength and good releasability from the photosensitive drum 101 because it rotates in contact with the photosensitive drum 101, and is also required to have a good contact with the toner. Good releasability is also required. If the releasability from the toner is poor, the residual toner that has not been completely removed by the cleaning device 108 may adhere to the surface of the charging roller 102, so that the difference in resistance between the toner-adhered portion and the non-adhered portion may occur. Will occur,
Causes poor charging.

When a resin alone is used as the material of the protective layer 203, the fluctuation of the electric resistance due to the environment is large, and the fluctuation of the charging potential of the photosensitive drum becomes large.
It is necessary to impart conductivity to the resin by using some method. As a means for adjusting the resistance value of the protective layer, one using a conductive additive is known. For example, Japanese Patent Application Laid-Open No. 4-1
Japanese Patent Application Publication No. 06565 discloses a technique in which carbon black is dispersed in a resin for forming a protective layer to reduce the resistance value of the protective layer. It is described that this technique has an effect of suppressing a change in a resistance value and a charging potential due to a change in environmental conditions and a decrease in image density. Similarly, Japanese Patent Application Laid-Open No. 7-9381 proposes a method in which metal salt conductive particles such as tin oxide are added to a resin as means for adjusting the resistance of a protective layer.

However, when carbon black or metal salt conductive particles are used, the resistance value of these particles is 1%.
Since it is as low as 0 ² Ω · cm or less, it is easily affected by the dispersion condition of these particles with respect to the resin, whereby the aggregated portion of fine conductive particles becomes an electrically conductive portion,
There has been a problem that sandy image density unevenness is likely to occur, and a leak is likely to occur at a contact portion with a photosensitive drum defect. Further, when the metal salt conductive particles are used, if the added amount is increased to such an extent that charging unevenness does not occur, the protective layer will significantly deteriorate in film strength. In general, the protective layer 203 as described above is formed by diluting a resin (addition of conductive particles as necessary) in a solvent, and performing a surface treatment such as spray coating or dipping on the semiconductive elastic layer using the diluted resin. ing.

However, due to the dispersibility of the conductive particles at the time of preparing the paint, (1) the image density and the charged potential fluctuate.
(2) There is a problem that the range of material selection is narrowed by the method, and (3) the equipment and process for forming the protective layer 203 are complicated, so that it is difficult to reduce the manufacturing cost of the charging roller.

Next, a description will be given of a charging current leak to a photosensitive member defect. The charging current flows due to the voltage applied from the conductive support 201, but if there is a photoconductor defect such as a pinhole, the charging current flows intensively toward the defect. Thereby, the vicinity of the defect of the photoconductor is not charged, and the obtained image has white spots (normal development) and black spots (reversal development).
Appears as. The resistance of the semiconductive elastic layer and the protective layer greatly influences the concentrated leakage of the charging current. In particular, when the resistance value of the protective layer is low, the portion of the charging failure becomes large. Therefore, if the resistance of the protective layer is sufficiently high,
This leak becomes a charging failure at one point corresponding to the defect (abuts on the defective portion), and a minimum image defect is required. However, setting the protective layer to a high resistance value lowers the charging ability of the charging roller.

[0013]

SUMMARY OF THE INVENTION A method for manufacturing a charging member according to the present invention has been made in view of the above-mentioned problems of the prior art, and its object is to use ultraviolet irradiation for forming a protective layer. It is an object of the present invention to provide a charging member which is excellent in releasability from a photoreceptor drum and releasability from a toner, prevents leakage of a charging potential to a photoreceptor defect, and can perform stable and uniform charging.

[0014]

A method for manufacturing a charging member according to claim 1 is a method for manufacturing a charging member having a semiconductive elastic layer formed on a conductive support, the method comprising: The protective layer is formed by irradiating the surface of the elastic layer with ultraviolet rays and modifying the surface of the elastic layer.

According to a second aspect of the present invention, there is provided a method for manufacturing a charging member.
In claim 1, the ultraviolet irradiation treatment is performed in an atmosphere of nitrogen gas, oxygen gas or carbon dioxide gas.

According to a third aspect of the present invention, there is provided a method for manufacturing a charging member.
The method according to claim 2, wherein the surface of the semiconductive elastic layer is subjected to a heat treatment before performing the ultraviolet irradiation treatment.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a charging member.
In claim 2, the surface of the semiconductive elastic layer is subjected to a heat treatment after the ultraviolet irradiation treatment.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a charging member.
The semiconductor device according to any one of claims 1 to 4, wherein the semiconductive elastic layer is formed of a material mainly containing epichlorohydrin rubber, which is a non-dispersed medium resistance material.

[0019] According to a sixth aspect of the present invention, there is provided a method for manufacturing a charging member.
The semiconductor device according to any one of claims 1 to 4, wherein the semiconductive elastic layer is formed of a medium-resistance thermoplastic elastomer material.

According to a seventh aspect of the present invention, there is provided a method for manufacturing a charging member.
In any one of the first to sixth aspects, the friction coefficient of the surface of the protective layer is adjusted to 0.1 to 1.2 by the ultraviolet irradiation treatment.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, taking a charging roller as a representative example of a charging member as an example. FIG. 1 is a schematic sectional view showing the structure of an ultraviolet irradiation device, and FIG. 2 is a plan sectional view thereof. FIG. 3 is a cross-sectional view of a charging roller manufactured using the ultraviolet irradiation device. 4A and 4B are explanatory views showing a method for evaluating the adhesion between the charging roller and the photoconductor, wherein FIG. 4A is a front view and FIG. 4B is a side view.

An ultraviolet irradiation apparatus 10 shown in FIGS. 1 and 2 includes an irradiation box 11, a support rotating portion 12 of a charging roller provided in the irradiation box 11, and a halogen heater both provided near the support rotating portion 12. A unit 13 and an ultraviolet light source 14 are provided. The irradiation box 1
1, a top plate is provided with an opening / closing member (not shown) for inserting and removing a charging roller, a gas supply section 11a at a lower portion, and a gas discharge section 11b at an upper portion. The support rotating unit 1
Numeral 2 is rotatable by a driving mechanism (not shown), and supports and rotates the charging roller 20 (or 102) in the vertical direction. The positions of the halogen heater unit 13 and the ultraviolet light source 14 are fixed. As the halogen heater unit 13, for example, a US-01 type E manufactured by Ushio Inc. with a rating of 100V can be used.

In the ultraviolet irradiation apparatus 10, the charging roller 20, the outermost layer of which is formed as a semiconductive elastic layer 22 (see FIG. 3), is fixed to the support rotating unit 12, and irradiated under an air atmosphere or as desired. By supplying / discharging a predetermined gas into / from the box 11, the air in the box is sufficiently replaced with this gas, and while continuing to supply / discharge this gas and rotating the charging roller, Is irradiated with ultraviolet light from an ultraviolet light source 14. The surface layer of the semiconductive elastic layer is modified by this ultraviolet irradiation treatment to form the protective layer 23 as shown in FIG. 21 is a conductive support.

In FIG. 3, the semiconductive elastic layer 22 is formed of epichlorohydrin rubber. JP-A-5-34
As disclosed in Japanese Patent No. 1627, this is not a synthetic rubber in which conductive particles are dispersed, but itself is a medium-resistance material. Better than one consisting of conductive particles / synthetic rubber. This does not complicate the layer configuration for charging unevenness of the charging roller, and is advantageous in terms of productivity of the charging roller. Further, in the present invention, a thermoplastic elastomer may be used as the material of the semiconductive elastic layer 22. Thermoplastic elastomers can be regenerated unlike rubber, which eliminates the need for a vulcanization step, is advantageous in reducing energy consumption and preventing environmental pollution, and also simplifies the charging roller manufacturing process. The charging roller can be provided at low cost.

Conventionally, the protective layer 203 of the charging roller 102
As the resin used for (FIG. 6), polyamide resin, fluorine resin, polyvinyl butyral resin and the like are used. As described above, (i) the image density and the charge are determined by the dispersibility of the conductive particles at the time of preparing the paint. The potential fluctuates, (ii)
The method of selection narrows the range of materials, (iii) the cost of the charging roller becomes difficult due to the complicated equipment and process for forming the protective layer 203, and (iv) the quality becomes unstable due to the complicated process. There was a problem such as easy.

On the other hand, in the present invention, since the protective layer 23 (FIG. 3) is formed by irradiating ultraviolet rays, the process is simple, and the characteristics (releasability and resistance value) required for the protective layer are simplified. And it can be obtained stably. Regarding ultraviolet rays to be irradiated, desirable wavelength, illuminance and irradiation time are set according to the material of the semiconductive elastic layer 22. The irradiation time is usually about 1 minute to 60 minutes. In the manufacture of the charging roller, it is necessary to uniformly irradiate the surface of the roller with ultraviolet rays. For this purpose, a method of rotating the roller with respect to an ultraviolet light source or a method of conveying the roller with a conveyor to emit the ultraviolet ray is used. A device that emits light from above and below the roller can be used.

[0027]

EXAMPLES Hereinafter, comparative examples and examples of the present invention will be described. Comparative Example 1 A charging roller 102 having the structure shown in FIG. 6 was manufactured. In this case, a rigid round bar made of stainless steel was used as the conductive support 201, and epichlorohydrin rubber (trade name: Epichromer CG, manufactured by Daiso Corporation) was used as the semiconductive elastic layer 202. Conductive support 20
1, a semiconductive elastic layer 202 is formed thereon, and a fluororesin (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate-based curing agent, epichlorohydrin rubber, silica Was coated to a film thickness of about 7 μm.

Comparative Example 2 A charging roller 102 having the structure shown in FIG. 6 was manufactured. In this case, a rigid round bar made of stainless steel is added as the conductive support 201, and carbon black is added to ethylene propylene rubber (trade name: EP21, manufactured by Nippon Synthetic Rubber Co., Ltd.) as the semiconductive elastic layer 202. Each of the prepared resin compositions was employed. A semiconductive elastic layer 202 is formed on a conductive support 201, and the semiconductive elastic layer 20 is further formed.
As a protective layer 203, carbon black (Denka HS-100, manufactured by Denka Co., Ltd.) was dispersed in a polyamide resin (Vestamelt T-171, manufactured by Daicel Huls) so as to be 7 wt% of the total solid content. About 7 resin compositions
It was coated to a thickness of μm.

Examples 1 to 6 A charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel was used as the conductive support 21, and epichlorohydrin rubber (trade name: Epichromer CG, manufactured by Daiso Corporation) was used as the semiconductive elastic layer 22. After forming the semiconductive elastic layer 22 on the conductive support 21, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays using the ultraviolet irradiating apparatus 10 of FIG. 1. In the ultraviolet irradiation, an ultraviolet lamp output 80 W / c is used as the ultraviolet light source 14.
m, a rated power of 2,000 W, and a high-pressure mercury lamp having a wavelength of 200 to 450 nm, and the irradiation time was changed to 30 seconds, 3 minutes, 10 minutes, and 30 minutes (Examples 1 to 4). In addition, a charging roller in which a protective layer 23 was formed by using a low-pressure mercury lamp having a rated power of 200 W and a wavelength of 100 to 300 nm and varying the irradiation time to 10 minutes and 60 minutes was also manufactured (Example 5,
6). In the following Examples 7 to 17, the ultraviolet irradiation device 10 of FIG. 1 was used in the same manner.

Example 7 A charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel was used as the conductive support 21, and a styrene-based thermoplastic elastomer was used as the semiconductive elastic layer 22. Conductive support 21
After the semiconductive elastic layer 22 was formed thereon, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays. For UV irradiation, UV lamp output 80W / c
m, a rated power of 2000 W, a high-pressure mercury lamp with a wavelength of 200 to 450 nm, and an irradiation time of 10 minutes.

Example 8 A charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel is used as the conductive support 21, and ethylene propylene rubber [trade name: EP21, Nippon Synthetic Rubber Co., Ltd.] is used as the semiconductive elastic layer 22.
Manufactured by the Company) and carbon black added. After the semiconductive elastic layer 22 was formed on the conductive support 21, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays. In the ultraviolet irradiation, a high-pressure mercury lamp having an ultraviolet lamp output of 80 W / cm, a rated power of 2000 W, and a wavelength of 200 to 450 nm was used, and the irradiation time was 10 minutes.

Examples 9 to 11 The charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel was used as the conductive support 21, and epichlorohydrin rubber (trade name: Epichromer CG, manufactured by Daiso Corporation) was used as the semiconductive elastic layer 22. After the semiconductive elastic layer 22 was formed on the conductive support 21, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays. In the ultraviolet irradiation, the air in the irradiation box 11 of FIG.
Using a low-pressure mercury lamp of ~ 300 nm (Sen Engineering Co., Ltd.), the irradiation time was changed to 1 minute, 5 minutes, and 10 minutes (corresponding to Examples 9, 10, and 11, respectively).

Example 12 A charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel was used as the conductive support 21, and epichlorohydrin rubber (trade name: Epichromer CG, manufactured by Daiso Corporation) was used as the semiconductive elastic layer 22. After the semiconductive elastic layer 22 was formed on the conductive support 21, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays. In the ultraviolet irradiation, the air in the irradiation box 11 shown in FIG.
The irradiation time was set to 10 minutes using a low-pressure mercury lamp of ~ 300 nm (Sen Engineering Co., Ltd.).

Example 13 A charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel was used as the conductive support 21, and epichlorohydrin rubber (trade name: Epichromer CG, manufactured by Daiso Corporation) was used as the semiconductive elastic layer 22. After the semiconductive elastic layer 22 was formed on the conductive support 21, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays. In the ultraviolet irradiation, the air in the irradiation box 11 of FIG. 1 was replaced with carbon dioxide gas, and the irradiation time was set to 10 minutes using a low-pressure mercury lamp (Sen Engineering Co., Ltd.) having a rated power of 200 W and a wavelength of 100 to 300 nm. .

Example 14 A charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel was used as the conductive support 21, and a styrene-based thermoplastic elastomer was used as the semiconductive elastic layer 22. After the semiconductive elastic layer 22 was formed on the conductive support 21, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays. In the ultraviolet irradiation, the air in the irradiation box 11 of FIG.
The irradiation time was set to 10 minutes using a low-pressure mercury lamp having a wavelength of 100 to 300 nm (Sen Engineering Co., Ltd.).

Example 15 A charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel is used as the conductive support 21, and ethylene propylene rubber [trade name: EP21, Nippon Synthetic Rubber Co., Ltd.] is used as the semiconductive elastic layer 22.
Manufactured by the Company) and carbon black added thereto. After the semiconductive elastic layer 22 was formed on the conductive support 21, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays. Fig. 1
Of the irradiation box 11 was replaced with nitrogen gas, and the irradiation time was set to 10 minutes using a low-pressure mercury lamp (Sen Engineering Co., Ltd.) having a rated power of 200 W and a wavelength of 100 to 300 nm.

Example 16 A charging roller 20 having the structure shown in FIG. 3 was manufactured. In this case, a rigid round bar made of stainless steel was used as the conductive support 21, and epichlorohydrin rubber (trade name: Epichromer CG, manufactured by Daiso Corporation) was used as the semiconductive elastic layer 22. After the semiconductive elastic layer 22 was formed on the conductive support 21, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays. That is, the roller on which the semiconductive elastic layer 22 is formed is set in the irradiation box 11 of FIG. 1, and the roller is heated at 80 ° C. for 30 minutes by the halogen heater unit 13 in an air atmosphere before irradiation with ultraviolet rays. After 30 minutes, the protective layer 23 was formed by irradiating the semiconductive elastic layer 22 with ultraviolet rays without heating the roller in a nitrogen atmosphere. In this ultraviolet irradiation, a rated power of 200 W and a wavelength of 1
A low-pressure mercury lamp of 00 to 300 nm [Sen Engineering Co., Ltd.] was used, and the irradiation time was 1 minute.

Example 17 A charging roller 20 having the structure shown in FIG. 3 was manufactured. Example 1
6 and the semiconductive elastic layer 2 on the conductive support 21 under the same conditions.
2 was prepared. This roller was set in the irradiation box 11 of FIG. 1, and the semiconductive elastic layer 22 was irradiated with ultraviolet rays under the same conditions as in Example 16 without heating the roller in a nitrogen atmosphere. One hour after the ultraviolet irradiation, the interior of the irradiation box 11 was returned to the air atmosphere, and the charging roller was heated by the halogen heater unit 13 at 80 ° C. for 30 minutes to form the protective layer 23.

In the above Examples 1 to 17, the roller (semiconductive elastic layer 22)
Was not heated, but ultraviolet irradiation and halogen heater 13
By performing the heating of the roller in parallel with the above, it was possible to produce a charging roller having excellent performance equivalent to that of the above-described embodiment by irradiating ultraviolet rays for a shorter time. Further, in the present invention, the surface layer of the elastic layer is not limited to the case where the surface layer is modified to be a protective layer by irradiating the surface with ultraviolet light, and the protective layer is formed of a polyamide resin, a fluororesin, or the like. Thereafter, by irradiating this protective layer with ultraviolet light, it has been confirmed that the ultraviolet light irradiation time can be shortened and the intended object of the present invention can be achieved. Further, in the above description, the charging roller is taken as the charging member. However, the present invention is not limited to this, and can be applied to a blade-shaped charging member made of rubber or a thermoplastic elastomer.

Next, a method of evaluating the quality of the charging roller manufactured in the comparative example and the example will be described. [Evaluation of Quality of Charging Roller] (1) Measuring method of friction coefficient of charging roller surface: Placing plain paper on a measuring table, placing the produced fixing roller thereon, and further placing a load of 500 g thereon. Then, the plain paper is pulled out, the torque at that time is measured, and the torque is obtained by dividing the torque by the load.

(2) Method of evaluating photoreceptor leakage and charging uniformity: Image evaluation was performed using the image forming apparatus shown in FIG. The photoconductor leak means a concentrated leak of a charging current to a photoconductor defect. Regarding this photoconductor leak,
The following ranking was performed. Rank 1: There is no white spot due to a leak on the image, or the diameter of the white spot is less than 2 mm.
Rank 2: A blank spot My diameter is 2 mm or more, but it is not streaked. Rank 3: Streak-like white spots have occurred on the image.

(3) Evaluation method of adhesion to photoreceptor: As shown in FIG. 4, four charging rollers 20 (and charging roller 1
02) is arranged in parallel with the photoreceptor 101, and the outer peripheral surfaces thereof are pressed against each other with a pressure of 1000 g using a rubber band 31. The resultant is left for 5 days in an environment of a temperature of 30 ° C. and a humidity of 90%, and
The adhesion between the charging roller and the photoconductor 101 was evaluated. The criteria for evaluation are the presence or absence of adhesion. In this case, the rubber band 31 was hooked on the conductive support 21 of the charging roller 20.

Tables 1 and 2 show the structures of the charging rollers according to Comparative Examples 1 and 2 and Examples 1 to 17, and Tables 3 and 4 show the evaluation results.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

As apparent from the above description, the following effects can be obtained according to the present invention. (1) In the method for manufacturing a charging member, the protective layer is formed by irradiating the surface of the semiconductive elastic layer with ultraviolet rays and modifying the surface to form a protective layer. A charging roller which is excellent in releasability, prevents leakage of charging current to a photoconductor defect, and can perform stable and uniform charging can be obtained. Further, the cost can be reduced by simplifying the manufacturing process.

(2) Claim 2 In this method of manufacturing a charging member, the ultraviolet irradiation is performed in an atmosphere of nitrogen gas, oxygen gas or carbon dioxide gas. In a short time, it is possible to manufacture a charging roller as excellent as that of the first aspect.

(3) In the method of manufacturing a charging member, the surface of the semiconductive elastic layer is heated before performing the ultraviolet irradiation treatment. Can be further reduced. Further, since the releasability is good as described above, the durability of the charging roller is also improved.

(4) In the manufacturing method of the charging member, the surface of the semiconductive elastic layer is heated after performing the ultraviolet irradiation treatment. Can be further reduced. Further, since the releasability is good as described above, the durability of the charging roller is also improved.

(5) Claim 5 In this method of manufacturing a charging member, the semiconductive elastic layer is formed of a material mainly composed of epichlorohydrin rubber, which is a non-dispersed medium-resistance material. Unlike the case where an elastic layer is formed using dispersed synthetic rubber (conductive agent / synthetic rubber), epichlorohydrin rubber itself has a medium resistance and does not cause electrical nonuniformity. The configuration is not complicated and the production is advantageous.
In addition, a charging member having higher withstand voltage than the conductive agent / synthetic rubber can be manufactured.

(6) A sixth aspect of the present invention provides a method for manufacturing a charging member, wherein the semiconductive elastic layer is formed of a medium-resistance thermoplastic elastomer material, unlike the case where the elastic layer is formed of rubber. Recycling is possible, and there is no need for a vulcanization step, which is advantageous in terms of reducing energy consumption and preventing environmental pollution. Further, the manufacturing process of the charging member is simplified, and the cost can be reduced.

(7) In the method for manufacturing a charging member, since the friction coefficient of the surface of the protective layer is set to 0.1 to 1.2 by the ultraviolet irradiation treatment, the charging due to uneven contamination on the surface of the charging member is performed. It is possible to suppress the occurrence of defects, the occurrence of fusion of the toner to the photoconductor, and the slip with the photoconductor. Further, it is effective for preventing sticking to the photoreceptor and stabilizing the charging potential with time by reducing abrasion of the charging member. The present invention can be effectively applied to an electrophotographic image forming apparatus such as a PPC copier, a laser printer, and a facsimile.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a structure of an ultraviolet irradiation device according to a charging member manufacturing method of the present invention.

FIG. 2 is a plan sectional view of FIG.

FIG. 3 is a cross-sectional view of a charging roller manufactured by the method of the present invention.

4A and 4B are explanatory diagrams illustrating a method for evaluating the adhesion between a charging roller and a photoconductor, wherein FIG. 4A is a front view and FIG. 4B is a side view.

FIG. 5 is an explanatory diagram illustrating a configuration of an image forming apparatus using a charging roller.

FIG. 6 is a cross-sectional view of a conventional charging roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ultraviolet irradiation apparatus 11 Irradiation box 11a Gas supply part 11b Gas discharge part 12 Support rotation part 13 Halogen heater unit 14 Ultraviolet light source (mercury lamp) 20 Charging roller 21 Conductive support 22 Semiconductive elastic layer 23 Protective layer 31 Rubber rubber 101 Photosensitive Body drum 102 Charging roller 103 Exposure 104 Developing roller 105 Power pack 106 Transfer roller 107 Recording paper 108 Cleaning device 109 Surface voltmeter 110 Image forming device 201 Conductive support 202 Semiconductive elastic layer 203 Protective layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Norihiko Yasue Ricoh Co., Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (7)

[Claims] 1. A method for manufacturing a charging member having a semiconductive elastic layer formed on a conductive support, wherein the surface of the semiconductive elastic layer is irradiated with ultraviolet rays to modify the surface. And forming a protective layer. 2. The method for manufacturing a charging member according to claim 1, wherein said ultraviolet irradiation treatment is performed in an atmosphere of nitrogen gas, oxygen gas or carbon dioxide gas. 3. The method for manufacturing a charging member according to claim 2, wherein the surface of the semiconductive elastic layer is subjected to a heat treatment before performing the ultraviolet irradiation treatment. 4. The method for manufacturing a charging member according to claim 2, wherein the surface of the semiconductive elastic layer is subjected to a heat treatment after performing the ultraviolet irradiation treatment. 5. The semiconductor device according to claim 1, wherein the semiconductive elastic layer is formed of a material mainly composed of epichlorohydrin rubber, which is a non-dispersed medium resistance material. A method for manufacturing a charging member. 6. The method for manufacturing a charging member according to claim 1, wherein said semiconductive elastic layer is formed of a medium-resistance thermoplastic elastomer material. 7. The method for manufacturing a charging member according to claim 1, wherein a coefficient of friction of the surface of the protective layer is adjusted to 0.1 to 1.2 by the ultraviolet irradiation treatment. .