JPH11167245A - Electrifying member and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrifying member having excellent environmental stability which does not cause image defects due to toner contamination of the electrifying member or melt sticking of a toner on the electrifying surface, by incorporating a specified polymer compd. into the outermost layer and preparing the polymer compd. having water-repellent groups. SOLUTION: This electrifying roller has a multilayered structure comprising a conductive core metal 2a, an elastic layer 2b concentrically formed as integrated with the core metal 2a by die molding or the like into a roller shape, and further an outermost layer 2d formed around the layer 2b. By using a material prepared by introducing water-repellent groups into a polymer compd. having carbon atoms and nitrogen atoms as the main chain for the outermost layer 2d, low water absorption, low surface energy and low hardness can be realized. As the polymer compd. having carbon atoms and nitrogen atoms in the main chain, a polyurethane resin and an acryl urethane resin can be used. Thereby, the obtd. roller has excellent environmental stability and durable stability and gives a good image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member and an electrophotographic apparatus having the same.

[0002]

2. Description of the Related Art A process of an electrophotographic apparatus such as an electronic copying machine and an electrostatic recording apparatus has a step of uniformly charging an object to be charged. As a charging method, a corona charging method is generally used. However, the corona charging method often generates products such as ozone, and requires additional means and mechanisms to cope with the problem. There is a problem that it is easy to increase the size and increase the cost.

Therefore, recently, a contact charging method has been studied as a new charging method replacing the corona charging method, and some of them have been put to practical use.

In the contact charging method, a charging member to which a voltage is applied is brought into contact with a charged body with a predetermined pressing force to charge the charged body. Since the generation of ozone is greatly reduced as compared with the corona charging method, there is an advantage that the corona charging method does not require any additional means or mechanism. As the applied voltage, a superimposed voltage of a DC voltage and an AC voltage having a peak-to-peak voltage that is about twice the charging start voltage when the DC voltage is applied to the charging member is often used.

[0005]

However, the above-mentioned charging member has the following problems.

[0006] The main constituent materials of the surface layer of the charging member are a binder material and a conductivity-imparting agent. As the binder material, resins such as polyurethane and polyamide are widely used in terms of economy and versatility.

However, these materials have high water absorption,
Since the electrical characteristics differ depending on the use environment, the environmental stability of charging is not sufficient.

[0008] In addition, it has the following problems.

For example, when a roller-shaped contact charging member is used in an electrophotographic apparatus, toner and paper dust adhere to the surface of the charging member or the surface of the member to be charged as the durability increases, resulting in poor charging or image defects due to contamination. May cause

[0010] This staining phenomenon is likely to occur when the surface energy of the surface of the charging member is high (the contact angle with water is small) and the surface hardness of the charging member is high. It often appears remarkably in an executed electrophotographic apparatus or a high-speed type electrophotographic apparatus.

The reason for this is that, when an AC voltage is used in combination with the applied voltage, the applied AC voltage causes vibration in the charging member, and pulsating pressure due to the vibration is applied to the contact portion between the charging member and the member to be charged. It is considered that this promotes the transfer and adhesion of the fouling substance such as toner from the surface of the charged body to the charging member surface and the fusion of the fouled substance such as toner to the surface of the charged body. Further, in a high-speed type electrophotographic apparatus, it is necessary to increase the frequency of the applied AC voltage in order to prevent the occurrence of charging unevenness corresponding to the frequency pitch of the AC voltage applied to the charging member. By increasing the number of times of pulsating pressure caused by the above-mentioned vibration generated in the contact portion with the charged body, the transfer and adhesion of a fouling substance such as toner from the surface of the charged body to the charging member surface and the toner and the like on the surface of the charged body It is believed that this further promotes the strong adhesion of

When contact charging is performed by applying only a DC voltage, the charging member does not vibrate as compared with the case where contact charging is performed by applying an AC voltage. Although image defects due to defective charging due to fusion or the like are reduced, image defects due to dirt on the surface of the charging member are likely to occur due to inferior charging ability.

Further, when only the DC voltage is applied, when the polarity of the bias applied to the charging member is opposite to the polarity of the toner charge, the toner or the like easily adheres to the charging member, so that further image defects occur. It will be easier.

The fusion of toner and the like to the surface of the member to be charged is a phenomenon peculiar to a contact-type charging member. However, even in a non-contact type charging member, particularly in a system in which charging is performed by applying an AC voltage. In addition, since toner, paper dust, and the like easily adhere to the surface of the charging member due to electric attraction, the same problem as that of the contact type charging member occurs.

Therefore, in order to solve the above problems, it is necessary to use a material having low water absorption, low surface energy and low hardness for the surface layer.

As the low-hardness material, there are a large number of the above-mentioned polyamides and urethanes, but it is difficult to achieve low water absorption and low surface energy.

On the other hand, materials having low water absorption and low surface energy include fluorine resin and silicone resin, but it is difficult to achieve low hardness.

As a remedy, a method of blending a low-grade material with a material having low hygroscopicity and low surface energy (cold blending or hot blending) can be considered. In addition to the lack of characteristics, there are drawbacks such as difficulty in obtaining required characteristics and restriction on material selection (eg, compatibility).

An object of the present invention is to provide a charging member and an electrophotographic apparatus having the same, which have excellent environmental stability and do not cause image defects due to toner contamination of the charging member and fusion of toner on the surface of the charged member. Is to do.

[0020]

That is, the present invention provides a charging member in which the outermost layer contains a polymer compound comprising a main chain containing at least a carbon atom and a nitrogen atom, wherein the polymer compound is A charging member having a group having water repellency.

Further, the present invention is an electrophotographic apparatus having the above charging member.

By using, as the outermost layer, a material in which a polymer having a carbon atom and a nitrogen atom in the main chain is introduced with a group having water repellency, low water absorption, low surface energy and low hardness can be achieved. It is possible to provide a charging member and an electrophotographic apparatus having the same, which have excellent environmental stability and do not cause image defects due to toner contamination of the charging member and fusion of the toner to the surface of the charged member.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the high molecular compound having a carbon atom and a nitrogen atom in the main chain include a polyurethane resin, an acrylic urethane resin and a polyamide resin.

The water-repellent groups include -F,-
Groups containing a fluorine atom such as CH ₂ F, —CHF ₂ , —CF ₃ , —CH ₂ CF _3, and —OCF ₃ , and [(CH
₃ ) ₂ SiO] _n , [(C ₂ H ₅ ) ₂ SiO] _n ,
[(C ₆ H ₅ ) ₂ SiO] _n , [(CH ₂ ＣＨCH) ₂ S
iO] _n , [(CH ₃ ) (C ₆ H ₅ ) SiO] _n ,
[(CH ₃ ) (CH ₂ ＣＨCH) SiO] _n and [(C _{6
H 5) (CH 2 = CH} ) SiO] compounds and containing silicon atoms of _{n such, [(CF 3 CH 2 CH} 2) 2 Si
O] _{n and} other compounds containing both a fluorine atom and a silicon atom.

Particularly, in the case of a polyurethane resin, it can be obtained by a reaction between a polyol and an isocyanate. By appropriately selecting the kind and the mixing ratio of the polyol and the isocyanate, chemical and physical properties are larger than those of other resins. This is preferable because it has a feature that different materials can be prepared relatively easily. At this time, the polymer compound used in the present invention can be obtained by using at least one of a polyol and an isocyanate into which a water-repellent group containing a silicon atom, a fluorine atom and the like has been introduced.

In general, as the isocyanate, those conventionally used can be used, for example, TDI, MD
I, NDI, TODI, HDI, IPDI, XDI, LDI and the like. Further, as described above, those in which a water-repellent group containing a silicon atom, a fluorine atom, or the like is introduced can be used.

As the polyol, those conventionally used can be used, such as polyethylene glycol (PEG) and polypropylene glycol (PPG).
And polytetramethylene ether glycol (PTM
G) and the like. Further, as described above, those in which a water-repellent group containing a silicon atom, a fluorine atom, or the like is introduced can be used.

The above isocyanates and polyols may be used alone or in combination of two or more.

In the polymer compound used in the present invention,
Since groups containing silicon atoms and fluorine atoms tend to be oriented on the surface, low water absorption and low surface energy can be effectively exhibited. It does not impair characteristics such as typical strength.

The content of at least one of silicon atoms and fluorine atoms in the polymer compound of the present invention is 0.01
10 to 10% by weight, preferably 0.1 to 5% by weight.
If the content is less than 0.01% by weight, the effect is insufficient, and
If the amount is more than 10% by weight, the properties of the modifying group become strong, and the properties of the polymer compound become insufficient. For example, in the case of the above-mentioned polyurethane resin, if less than 0.01% by weight,
Problems such as poor environmental stability and toner contamination, 10% by weight
When the value exceeds, problems such as toner fusion to a charged member (photoreceptor) due to an increase in hardness are likely to occur.

The amount of at least one of fluorine atoms and silicon atoms introduced can be quantified by performing composition analysis and determining the number of atoms occupying one unit of the repeating structure of the polymer compound.

The hardness of the surface of the charging member of the present invention is not more than 90 degrees, preferably not more than 85 degrees.
If it exceeds 90 degrees, although the charging characteristics are good, fusion of the toner or the like to the member to be charged is likely to occur, which may cause an image defect. Therefore, it is necessary to use a relatively low hardness polyurethane resin to be contained in the outermost layer. The surface hardness is a value measured by a micro rubber hardness meter manufactured by Kobunshi Keiki Co., Ltd.

These polymer compounds used for the outermost layer include:
A conductivity-imparting agent, a lubricant, a curing agent, and other additives may be added. Examples of the conductivity-imparting agent include carbon black and graphite, metal oxides such as titanium oxide, tin oxide and zinc oxide, and metal powders such as gold, silver, copper and nickel. You may use it in combination of 2 or more types.

As a method of forming the outermost layer, the above-mentioned polymer compound is formed into a coating material and formed into a tube by a suitable method such as dip coating and roll coating, or a suitable means such as a die or extrusion. May be coated. At this time, when the tube has heat shrinkability, the inner diameter is made larger than that of the support, and after the support is inserted into the tube, it can be covered by heat shrinkage. In the case where the tube does not have heat shrinkability, the tube may be made smaller in inner diameter than the support, and may be fitted after being expanded by a suitable means such as air.

In the present invention, a conductive elastic layer may be provided if necessary.

For the conductive elastic layer, for example, ethylene propylene rubber (EPDM), nitrile rubber (NBR), styrene butadiene rubber (SBR), butadiene rubber (B
R), isoprene rubber (IR), chloroprene rubber (C
R), rubber materials such as acrylic rubber (ACM), silicone rubber, and fluoro rubber, and thermoplastic elastomers such as polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, and polyamide can be used.

The elastic layer may be made of either a solid or a sponge, but a sponge is preferable from the viewpoint of reducing charging noise.

FIG. 1 is a schematic structural view of an example of an electrophotographic apparatus having the charging member of the present invention.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) as a member to be charged, and is rotated at a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow. 1a is a conductive drum support made of aluminum or the like of the photosensitive drum 1, and 1b is the drum support 1a.
Is a photosensitive layer formed on the outer peripheral surface of the photosensitive layer.

Reference numeral 2 denotes a contact charging member. This embodiment is a roller body (hereinafter, referred to as a charging roller) which is disposed substantially in parallel to the surface of the photosensitive drum 1 and in contact with the drum genera by a predetermined pressing force. Then, the photosensitive drum 1 is driven to rotate.

As shown in FIG. 2, the charging roller 2 of this embodiment includes a conductive metal core 2a and an elastic layer 2b of a conductive rubber or the like formed concentrically and integrally with the metal core by molding or the like into a roller shape. When,
Further, it has a composite layer structure including the outermost layer 2d formed on the outer periphery. Further, if necessary, an intermediate layer 2c can be provided between the elastic layer 2b and the outermost layer 2d. In the charging roller 2 of this embodiment, the above-described polymer compound is used for the outermost layer 2d, which is a material layer that is in contact with the surface of the photosensitive drum 1, which is a member to be charged.

Reference numeral 3 denotes a power supply for applying a voltage to the charging roller 2. By applying a predetermined voltage from the power supply to the metal core 2 a of the charging roller 2, the peripheral surface of the rotating photosensitive drum 1 has a predetermined polarity and potential. Is charged by a contact charging method.

The voltage to the charging roller 2 may only DC voltage is a DC voltage V _DC and an AC voltage V _AC superposed voltage to a uniformly charged photosensitive drum 1 surface of the member to be charged (oscillating voltage) Is preferably applied.

The surface of the photosensitive drum 1 which has been uniformly primary-charged to a predetermined potential by the charging roller 2 is subjected to laser beam scanning exposure 4 of target image information by a laser scanner (image exposure means) (not shown), and a developing unit 5. The steps of toner development and transfer of the formed toner image to the transfer material 7 by the transfer means 6 are sequentially performed, and the transfer material 7 that has been transferred from the surface of the photosensitive drum 1 after receiving the toner image is introduced into a fixing means (not shown). It is output as an image formed product (print). After the transfer of the toner image, the surface of the photosensitive drum 1 is cleaned by a cleaning device 8 to remove adhered and contaminated matter of toner remaining after transfer, and is repeatedly used for image formation.

[0045]

Embodiments will be described below. (Example 1) [Preparation of compound for elastic layer] 100 parts by weight of EPDM, 5 parts by weight of zinc oxide, 1 part by weight of higher fatty acid, 5 parts by weight of conductive carbon black, 10 parts by weight of paraffin oil, 2 parts by weight of sulfur, 1 part by weight of a vulcanization accelerator MBT, 1 part by weight of a vulcanization accelerator TMTD and a vulcanization accelerator ZnMDC
1.5 parts by weight were mixed for 20 minutes while cooling with two rolls to prepare a compound.

[Preparation of paint for outermost layer] Fluorine-introduced polyol (PTMG) 80 parts by weight Isocyanate (TDI) 20 parts by weight DMF 100 parts by weight Conductive titanium oxide 40 parts by weight is kneaded using a small bead mill, and urethane paint Was prepared.

[Preparation and evaluation of charging roller] 6 m in diameter
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on the rubber roller and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 10 μm. The content of fluorine in the polyurethane resin is 1.0
% By weight, and the micro hardness of the surface was 79 degrees.

This charging roller was attached to the primary charging position of a cartridge used in a laser beam printer (Laser Jet 4si, manufactured by Hewlett-Packard Company). DC voltage -750 V AC voltage 2.0 kV (peak-to-peak voltage) Frequency 650 Hz bias To a low-temperature, low-humidity environment (15 ° C-10% R
H), an initial image evaluation and a durability test were performed in a high temperature and high humidity environment (32.5 ° C.-80% RH). Table 1 shows the results.

(Example 2) [Preparation of compound for elastic layer] Same as Example 1 [Preparation of paint for outermost layer] Same as Example 1 except that the amount of fluorine introduced into the polyol was changed.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on the rubber roller, and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 12 μm. The content of fluorine in the polyurethane resin is 0.0
1% by weight, and the micro hardness of the surface was 76 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 3) [Preparation of compound for elastic layer] Same as Example 1 [Preparation of paint for outermost layer] Same as Example 1 except that the amount of fluorine introduced into the polyol was changed.

[Preparation and Evaluation of Charging Roller] 6 m in diameter
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was applied onto the rubber roller by dip coating, and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 11 μm. The content of fluorine in the polyurethane resin is 10.
0% by weight, and the micro hardness of the surface was 85 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 4) [Preparation of compound for elastic layer] Same as Example 1 [Preparation of paint for outermost layer] Same as Example 1 except that the amount of fluorine introduced into the polyol was changed.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on this rubber roller, and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 10 μm. The content of fluorine in the polyurethane resin is 0.1
% By weight, and the micro hardness of the surface was 77 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 5) [Preparation of compound for elastic layer] Same as in Example 1 [Preparation of paint for outermost layer] Same as Example 1 except that the amount of fluorine to be introduced into polyol was changed.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on the rubber roller and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 14 μm. The content of fluorine in the polyurethane resin is 5.0
% By weight, and the micro hardness of the surface was 81 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 6) [Preparation of compound for elastic layer] Same as in Example 1 [Preparation of paint for outermost layer] Polydimethylsiloxane chain-introduced polyol (PTMG) 80 parts by weight Isocyanate (TDI) 20 parts by weight DMF 100 30 parts by weight of conductive titanium oxide was kneaded using a small bead mill to prepare a urethane paint.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on the rubber roller and dried by heating at 80 ° C. for 30 minutes to obtain a charging roller having an outermost layer having a thickness of 14 μm. Silicon content in polyurethane resin is 1.3
% By weight, and the micro hardness of the surface was 80 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 7) [Preparation of compound for elastic layer] Same as in Example 1 [Preparation of paint for outermost layer] Fluorine and polydimethylsiloxane chain-introduced polyol (PTMG) 80 parts by weight Isocyanate (TDI) 20 parts by weight 100 parts by weight of DMF and 35 parts by weight of conductive titanium oxide were kneaded using a small bead mill to prepare a urethane paint.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on the rubber roller, and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 11 μm. The content of fluorine in the polyurethane resin is 1.0
% By weight, the content of silicon was 1.0% by weight, and the micro hardness of the surface was 81 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 8) [Preparation of compound for elastic layer] Same as in Example 1 [Preparation of paint for outermost layer] Fluorine-introduced polyol (PTMG) 75 parts by weight Isocyanate (TDI) 25 parts by weight DMF 100 parts by weight Forty parts by weight of titanium oxide was kneaded using a small bead mill to prepare a urethane paint.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on the rubber roller and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 10 μm. The content of fluorine in the polyurethane resin is 1.0
% By weight, and the micro hardness of the surface was 90 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 9) [Preparation of compound for elastic layer] 100 parts by weight of EPDM, 5 parts by weight of zinc oxide, 1 part by weight of higher fatty acid, 5 parts by weight of conductive carbon black, 10 parts by weight of paraffin oil, 2 parts by weight of sulfur Parts, vulcanization accelerator MBT 1 part by weight, vulcanization accelerator TMTD 1 part by weight, vulcanization accelerator ZnMDC1.
5 parts by weight and 10 parts by weight of a foaming agent (sodium bicarbonate) were mixed for 20 minutes while cooling with two rolls to prepare a compound.

[Preparation of Tube for Outermost Layer] 80 parts by weight of fluorine-introduced polyol (PTMG) 20 parts by weight of isocyanate (TDI) 40 parts by weight of conductive titanium oxide were kneaded using a two-roll mill, and a high solid content and high viscosity were obtained. Was obtained.

This polymer compound was heated and molded using a mold to produce a tube having an inner diameter of 11 mm and a thickness of 500 μm.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the above-mentioned compound for an elastic layer was heated and foamed and vulcanized at 150 ° C. for 15 minutes on a stainless steel core metal of m to obtain a sponge roller having an elastic layer having a thickness of 3 mm.

Next, the outermost layer tube was fitted onto the sponge roller while expanding the inner diameter by using air to form a charging roller. The content of fluorine in the polyurethane resin was 1.0% by weight, and the micro hardness of the surface was 80 degrees.

The charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 10) [Preparation of compound for elastic layer] Same as in Example 1 [Preparation of paint for outermost layer] 40 parts by weight of fluorinated polyol (PTMG) 40 parts by weight of fluorinated polyol (PEG) Isocyanate (TDI) 20 parts by weight DMF 100 parts by weight Conductive titanium oxide 40 parts by weight was kneaded using a small bead mill to prepare a urethane paint.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on the rubber roller and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 11 μm. The content of fluorine in the polyurethane resin is 1.0
% By weight, and the micro hardness of the surface was 81 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Comparative Example 1) [Preparation of compound for elastic layer] Same as in Example 1 [Preparation of paint for outermost layer] Polyol (PTMG) 80 parts by weight Isocyanate (TDI) 20 parts by weight DMF 100 parts by weight Conductive oxidation 40 parts by weight of titanium was kneaded using a small bead mill to prepare a urethane coating.

[Preparation and Evaluation of Charging Roller] 6 m in diameter
First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a m stainless steel core bar to obtain a rubber roller having a 3 mm-thick elastic layer.

Next, the coating for the outermost layer was dip-coated on the rubber roller and dried by heating at 100 ° C. for 20 minutes to obtain a charging roller having an outermost layer having a thickness of 10 μm. The micro hardness of the surface was 80 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Comparative Example 2) [Preparation of compound for elastic layer] Same as in Example 1 [Preparation of coating for outermost layer] 50 parts by weight of commercially available polyurethane resin coating (clear) 50 parts by weight of commercially available fluororesin coating (clear) Part DMF 100 parts by weight Conductive titanium oxide 40 parts by weight was kneaded using a small bead mill to prepare a coating.

[Preparation and Evaluation of Charging Roller] Diameter 6 m
First, the compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel cored bar having a thickness of 3 mm to obtain a rubber roller having an elastic layer having a thickness of 3 mm.

Next, the coating for the outermost layer was dip-coated on the rubber roller, and dried by heating at 100 ° C. for 25 minutes to obtain a charging roller having an outermost layer having a thickness of 15 μm. The content of fluorine in the polyurethane resin / fluororesin was 5.0% by weight, and the micro hardness of the surface was 93 degrees.

This charging roller was evaluated in the same manner as in Example 1. Table 1 shows the results.

[0096]

[Table 1]

[0097]

According to the present invention, it has become possible to provide a charging member which is excellent in environmental stability and durability stability and can obtain a good image, and an electrophotographic apparatus having the same.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an example of an electrophotographic apparatus using a charging member of the present invention.

FIG. 2 is a longitudinal sectional view showing an example of the charging member of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 2a Core metal 2b Elastic layer 2c Intermediate layer 2d Outermost layer 3 Voltage application power supply 4 Image exposure means 5 Developing means 6 Transfer means 7 Transfer material 8 Cleaning means

Claims (5)

[Claims] An outermost layer is a charging member containing a polymer compound having a main chain containing at least carbon atoms and nitrogen atoms, wherein the polymer compound has a group having water repellency. Charging member. 2. The charging member according to claim 1, wherein the water-repellent group has at least one of a silicon atom and a fluorine atom. 3. The content of at least one of silicon atoms and fluorine atoms in the polymer compound is 0.01 to 1
3. The charging member according to claim 1, wherein the amount is 0% by weight. 4. The charging member according to claim 1, wherein the micro hardness of the charging member is 90 degrees or less. 5. An electrophotographic apparatus having an electrophotographic photosensitive member, a latent image forming unit, a unit for developing a formed latent image, and a unit for transferring a developed image to a transfer material, wherein the photosensitive member is used as the latent image forming unit. An electrophotographic apparatus comprising the charging member according to any one of claims 1 to 4 for charging an image.