JPH11295967A - Electrifying member and electrifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve stable performance over a long term without causing the deterioration of the performance due to the adhesion of toner by forming one or plural layers having a specified storage elastic modulus on the outside of an elastic layer directly or through another layer. SOLUTION: This member is provided with an outer layer 4 consisting of one or plural layers formed on the outside of the elastic layer 3 directly or through another layer, and the respective layers are adjusted so that a ratio difference between the storage elastic modulus (E') of each layer and the E' of the adjacent layer thereof may be within 500. The elastic layer 3 is formed of rubber, resin or foaming body used in the conventional device. The layer 4 is ordinarily formed of coating film consisting of various kinds of resin, and the E' is adjusted to be within a desired range by applying cross-linking processing to the resin. It is desirable to adjust volume resistivity to 10<3> to 10<12> Ωcm by adding conductive agent to the layer 4 so that conductivity may be applied or adjusted. It is desirable to make the layer 4 a thin layer so as not to spoil the flexibility of the elastic layer 3, to put it concretely, it is desirable to set the thickness of the layer 4 <=1 mm, especially, <=800 cm, more desirably, 20 to 600 μm.

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 for charging an object to be charged such as a photoreceptor used in an electrostatic latent image process in a copying machine, a printer, and the like, and a charging device using the same. About.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic process such as a copying machine or a printer, first, the surface of a photoreceptor is charged uniformly.
An image is projected from the optical system onto the photoreceptor to form a latent image by erasing the charged portion of the light, and then a toner image is formed by toner adhesion, and a toner is formed on a recording medium such as paper. Printing is performed by transferring an image.

In this case, a corona discharge method has been generally adopted as an operation for initially charging the photosensitive member. However, since this corona discharge method requires application of a high voltage of 6 to 10 kV, it is not preferable from the viewpoint of safe maintenance of the machine. In addition, there is an environmental problem because harmful substances such as ozone are generated during corona discharge.

[0004] For this reason, efforts have been made for a charging system that can perform charging with an applied voltage lower than that of corona discharge and can suppress generation of harmful substances such as ozone. As an attempt of such a charging method, there has been proposed a contact method in which a charging member to which a voltage is applied is brought into contact with a member to be charged such as a photosensitive member at a predetermined pressure to charge the member to be charged.

As a charging member used in the contact charging system, for example, a resin solution of nylon, acrylic, urethane or the like is applied to the surface of an elastic layer such as rubber or urethane foam by dipping or spraying. A coating film layer is known.

[0006]

However, in this contact charging method, since the charging member and the member to be charged are always in contact, a corona system in which the member to be charged is charged in a non-contact manner by a discharge from a conventional wire or the like. Compared to
The durability of the charging member tends to be a problem.

[0007] Residual toner greatly affects the durability of the charging member in this contact charging system. That is, a small amount of toner remaining on the surface of the photosensitive drum gradually adheres to the charging member due to poor transfer and poor cleaning. In severe cases, the toner is embedded and fixed on the surface of the charging member, which causes poor charging. Originally, to solve such a problem, the fundamental measure is to improve the transfer efficiency and the cleaning efficiency so that the residual toner does not reach the charging section by the charging member. It is difficult to eliminate 100%. In order to prevent the residual toner from adhering to the surface of the charging member, it has been proposed to coat the surface of the charging member with a fluorine-based material having excellent antifouling properties. At present, durability has not been obtained.

In this case, the residual toner does not seem to adversely affect the image to the extent that the residual toner slightly adheres to the surface of the charging member. It seems that the residual toner is embedded in the charging member surface from a state of simply adhering to the charging member surface, and once embedded in the charging member, the residual toner starts accumulating at an accelerated rate, and at this point, the image is Bad things begin to appear.

The present invention has been made in view of such circumstances, and even when used in an electrostatic latent image process of a copying machine, a printer, or the like, the performance is maintained for a long time without causing deterioration in performance due to toner adhesion. It is an object of the present invention to provide a charging member having excellent durability and capable of exhibiting stable performance, and a charging device using the charging member.

[0010]

Means for Solving the Problems and Embodiments of the Invention As a result of diligent studies to achieve the above object, the present inventor has found that an elastic layer is provided directly or through another layer outside the elastic layer. And a storage elastic modulus (E ') of each layer constituting the charging member and a storage elastic modulus (E') of an adjacent layer. It has been found that by preparing each layer such that the difference in the ratio is within 500 times, a stable charging operation can be performed over a long period of time without deteriorating the performance of the charging member due to toner adhesion. It is completed.

Therefore, according to the present invention, by applying a voltage between the object to be charged and the object to be charged,
A charging member for charging an object to be charged has an elastic layer, and an outer layer composed of one or more layers formed directly or via another layer outside the elastic layer, and the storage elasticity of each layer. A charging member, wherein the difference between the ratio (E ′) and the storage elastic modulus (E ′) of the adjacent layer is within 500 times, and the member to be charged is brought into contact with the member to be charged. A charging device comprising: a charging member to be charged; and voltage applying means for applying a voltage between the member to be charged and the charging member, wherein the charging member of the present invention is used as the charging member. Provide a charging device.

Hereinafter, the present invention will be described in more detail.
As described above, the charging member of the present invention has an elastic layer and an outer layer formed on the outside of the elastic layer. Any form may be used as long as the charge can be uniformly applied to the member to be charged by application, for example, a roll shape,
Various shapes such as a plate shape and a block shape can be used, but usually a roll shape is preferable. In the case of a roll shape, for example, as shown in FIG. 1, the elastic layer 3 is formed on the outer periphery of the shaft 2, and outside the elastic layer 3,
The charging member 1 on which the outer layer 4 is formed can be exemplified.
In this case, a metal or plastic shaft can be used for the shaft 2, and depending on the form of the charging member, the mechanism of the charging device in which the charging member is used, and the like.
This shaft 2 can be omitted.

The elastic layer 3 may be any elastic material that satisfies the condition of storage elastic modulus (E ') described later, and may be rubber, resin, or foam which has been conventionally used as an elastic layer of a charging member. Can be formed. Specifically, polyurethane, silicone rubber, butadiene rubber,
Isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, a rubber composition having a base rubber such as epichlorohydrin rubber is exemplified, but polyurethane is particularly preferred. More preferably, a polyurethane foam having an expansion ratio of 1.5 to 50 times is used. The foaming density in this case is 0.05 to
About 0.9 g / cm ³ is appropriate.

A conductive agent is added to the elastic layer 3.
Thereby, a predetermined conductivity can be imparted. Its guidance
The electric agent is not particularly limited, and may be lauryl trimethyl alcohol.
Ammonium, stearyltrimethylammonium, octane
Tadodecyl trimethyl ammonium, dodecyl trimethyl
Luammonium, hexadecyltrimethylammonium
Dimethyl ethyl ammonium perchlorate
Acid salt, chlorate, borofluoride, ethosulfate
Halogenation of salt, benzyl bromide, benzyl chloride, etc.
Cationic field of quaternary ammonium salts such as benzyl salts
Surfactants, aliphatic sulfonates, higher alcohol sulfates
Steal salt, higher alcohol ethylene oxide added sulfuric acid
Ester salt, higher alcohol phosphate ester salt, higher alcohol
Acetonitrile such as phosphoric acid oxide addition phosphate salt
Zwitterionic surfactants such as on-surfactants and various betaines
Agent, higher alcohol ethylene oxide, polyethylene
Glycol fatty acid esters, polyhydric alcohol fatty acid esters
Antistatic agents such as nonionic antistatic agents such as tellurium, LiC
F_ThreeSO_Three, NaClO_Four, LiAsF₆, LiBF_Four, N
aSCN, KSCN, Li such as NaCl⁺, Na⁺, K⁺
Metal salt of Group 1 of the Periodic Table, or NH_Four ⁺Such as salt
Electrolyte and Ca (ClO_Four)_TwoCa such as²⁺ , Ba²⁺ etc
Metal salts of the second group of the periodic table, and their antistatic agents
Has at least one or more hydroxyl groups, carboxyl groups,
Activity that reacts with isocyanates such as secondary or secondary amine groups
And those having a group having an acidic hydrogen. Furthermore,
1,4-butanediol, ethylene glycol
, Polyethylene glycol, propylene glycol,
Polyhydric alcohols such as polyethylene glycol and their derivatives
Or ethylene glycol monomethyl ate
Mono such as ter, ethylene glycol monoethyl ether
Ion conductive agent such as complex with all, or Ketjembler
EC, conductive carbon such as acetylene black, S
AF, ISAF, HAF, FEF, GPF, SRF, F
Rubber carbon such as T, MT, etc., oxidized color
(Ink) carbon, pyrolytic carbon, natural grapher
Site, artificial graphite, antimony-doped tin oxide,
Titanium oxide, zinc oxide, nickel, copper, silver, germanium
Metals and metal oxides, polyaniline, polypillow
And conductive polymers such as polyacetylene.
You. In this case, the amount of these conductive agents depends on the type of the composition.
And the volume resistivity of the elastic layer 3 is usually 1
0⁰-10⁸Ω · cm, preferably 10^Two-10⁶Ω · cm
It is adjusted so that

The outer layer 4 may be any one that satisfies the condition of storage elastic modulus (E ') described later, but can usually be formed by a coating film made of various resins.
Specifically, polyester resin, acrylic resin, urethane resin, acrylic urethane resin, nylon resin, epoxy resin, polyvinyl acetal resin, vinylidene chloride resin, fluororesin, silicone resin, etc. are exemplified, and any of organic and aqueous ones In particular, when the outer layer 4 is formed directly on the elastic layer 3, a water-based resin is preferably used in order to ensure smoothness. Since the elastic body does not swell even when the elastic body to be formed is dipped in the water-based resin paint, a good surface smoothness can be easily obtained, and a charging member excellent in anti-toner adhesion and durability can be obtained. Obtainable. As the water-based resin, if the solvent is water, any of a water-soluble type, an emulsion type, a suspension type and the like may be used. In particular, a resin having an active hydrogen such as a carboxyl group, a hydroxyl group or an amino group is preferably used. Specific examples of such an aqueous resin include polyester-based, acrylic-based, urethane-based, and hot-water-soluble resins such as polydioxolane.
In particular, an acrylic resin is preferably used.

The resin forming the outer layer 4 is subjected to a crosslinking treatment so that the storage elastic modulus (E ') of the outer layer 4 can be adjusted to a desired range. In this case, the cross-linking agent is appropriately selected according to the type of the resin to be used and the like, and may be any one as long as a desired cross-linking effect can be obtained.
For example, an epoxy-based, oxazoline-based, melamine-based, isocyanate-based, or phenol-based cross-linking agent can be exemplified. In particular, an epoxy-based or oxazoline-based cross-linking agent is preferably used from the viewpoints of a cross-linking effect and low hardness. The amount of the crosslinking agent is not particularly limited, but is usually in the range of 0.1 to 50 parts by weight based on 100 parts by weight of the resin.

A conductive agent is added to the outer layer 4 to make it conductive.
Can be given or adjusted, and the volume resistivity is usually 1
0^Three-10¹² Ωcm, especially 10^Five-10^TenΩcm
It is preferable to adjust as follows. In this case, as a conductive agent
Is the same conductive agent as that exemplified in the elastic layer 3 above.
However, carbon is particularly preferably used.
You. The amount of conductive agent added depends on the type of conductive agent, etc.
Appropriately selected so as to obtain volume resistivity, particularly limited
Although it is not a thing, when using carbon as a conductive agent
Is usually 0.01 to 60% by weight, especially 10 to 40% by weight
Degree.

Further, appropriate additives such as thickeners, thixotropy-imparting agents and structural viscosity-imparting agents can be added to the outer layer 4 as necessary. May be either inorganic or organic.

The thickness of the outer layer 4 is not particularly limited, but is preferably a thin layer so as not to impair the flexibility of the elastic layer 3, specifically 1 mm or less, particularly 8 mm.
It is preferably not more than 00 μm, more preferably 20 to 600 μm.

Although not specifically shown in FIG. 1, one or two or more coating films are further provided on the outer layer 4 for the purpose of preventing toner adhesion and ensuring surface smoothness. The outer layer may have a multilayer structure of two or more layers.

This coating film can be formed of any suitable resin such as nylon, polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, epoxy resin, urethane resin, urea resin, fluororesin, etc. according to the purpose. In particular, a fluororesin is preferably used from the viewpoint of the surface smoothness of the charging member and low adhesion to a photoreceptor or the like.

Examples of the fluororesin include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, Polychlorotrifluoroethylene, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, and the like, and a dispersion-type aqueous fluororesin obtained by dispersing these fine particles in water is particularly preferably used. ,
More preferably, a dispersion type aqueous fluororesin in which fine particles of polytetrafluoroethylene are dispersed in water is used. The particle size of the fluororesin fine particles used is not particularly limited, but is preferably 5 μm or less, particularly preferably 0.05 to 1 μm.

Further, a coating film may be formed by mixing other resins with these fluororesins as long as the effect of the fluororesins is not impaired. In this case, as the other resin mixed with the fluororesin, polyvinyl acetal resin, urethane resin, polyester resin, acrylic resin,
Examples thereof include a nylon resin, an epoxy resin, and a vinylidene chloride-based copolymer, and one or more of these can be mixed with the fluororesin to form the coating film.
Among these resins, polyvinyl acetal resin, urethane resin, polyester resin, and vinylidene chloride-based copolymer are preferable from the viewpoint of film formation and uniformity of the fluororesin, and polyvinyl acetal resin is particularly preferably used.

A conductive agent may be added to the coating film to impart or adjust conductivity. In this case, the conductive agent is not particularly limited, but carbon is preferably used, and particularly, It is preferable to use carbon as a conductive agent for the outermost layer forming the surface of the member. In this case, the carbon used for the outermost layer is not particularly limited, but preferably has an oxygen content of 5% or more, particularly 7% or more, and more preferably 9% or more, and has a pH of 5% or more. As described above, it is particularly preferably 6 or more, and more preferably 7 or more. That is, the oxygen content of ordinary carbon is 0.1
３3%, some of which have been oxidized, but the oxidized carbon tends to shift its pH toward the acidic side as the oxygen content increases slightly. In some cases, when the carbon becomes acidic, the stability may decrease when added to an aqueous resin (specifically, an aqueous fluororesin). On the other hand, the carbon suitably used in the present invention maintains neutrality or alkalinity despite having a high oxygen content, and can be stably added to the aqueous fluororesin. .
Although the detailed structure of carbon having such an oxygen content and pH is not clear, a functional group such as a carboxyl group, a hydroxyl group, or a ketone group is attached to the carbon surface, and a part of the hydrogen contained in these functional groups is removed. Those substituted with an alkali metal such as sodium are preferably used.

The amount of the conductive agent to be added depends on the desired resistance.
It can be adjusted appropriately to obtain. in this case,
The resistance of the coating film is 10^Three-10¹² Ω · cm, special
To 10^Five-10^TenΩ · cm is preferable.
Control the amount of conductive agent to achieve such volume resistivity.
When carbon is used as conductive agent
Is usually 0.01 to 40% by weight of the outer layer, especially
It is about 5 to 20% by weight.

In addition, an appropriate additive such as a thickener, a thixotropy-imparting agent, and a structural viscosity-imparting agent can be added to this coating film as needed. May be either inorganic or organic.

The thickness of the coating is not particularly limited, but is preferably 30 μm or less, particularly preferably 1 to 15 μm. If the thickness of the coating exceeds 30 μm, the coating becomes hard. The flexibility may be impaired, the durability may be reduced, and cracks may occur during use.

The method of forming the outer layer 4 is not particularly limited, but a method of preparing a paint containing each component and applying the paint by dipping or spraying to form a coating film is preferably used. Can be In this case, in the case where the outer layer is formed as a plurality of layers including the above-mentioned coating film, dipping and spraying may be repeated using a paint for forming each layer. In addition, as the method for forming the outer layer 4, the above-described dipping method and spray method are preferably adopted, but the method is not limited thereto, and may satisfy the condition of the difference in storage elastic modulus (E ') described later. If so, it may be formed by extrusion or the like.

In the present invention, the difference between the storage elastic modulus (E ') of each layer constituting the charging member and the storage elastic modulus (E') of the adjacent layer is within 500 times, preferably 1%.
It is adjusted so as to be within 00 times, more preferably within 80 times.

Here, the adjacent layer means all the layers in contact with the layer of interest, for example, a roller shape consisting of three layers of an elastic layer, an inner outer layer, and an outer outer layer from the inside. In the case of the charging member, the elastic layer has a difference in storage elastic modulus (E ') with the inner outer layer, the inner outer layer has a difference in storage elastic modulus (E') with the elastic layer, and the storage elasticity with the outer outer layer. The difference in the ratio of the modulus (E ′) and the difference in the ratio of the storage modulus (E ′) of the outer outer layer to that of the inner outer layer are targeted. The ratio difference is (storage modulus value of the layer having the larger storage modulus) /
(Storage modulus value of the layer having the smaller storage modulus).

As described above, the charging member of the present invention only needs to have a difference between the storage elastic modulus (E ') of each layer and the storage elastic modulus (E') of an adjacent layer within 500 times. Although the storage elastic modulus (E ') of each layer is not limited, the storage elastic modulus (E') of the elastic layer 3 is preferably 5 × 10 ⁷ dyn / cm ² or less, more preferably 1 × 10 ⁷ dyn / cm ² or less. × 10 ⁷ d
yn / cm ² or less, and the storage elastic modulus (E ′) of the outer layer including the outer layer is preferably 5 × 10 ¹⁰ dyn / cm ² or less, more preferably 5 × 10 ⁹ dyn.
/ Cm ² or less.

The storage elastic modulus (E ') of each of the above layers can be measured by a dynamic viscoelasticity measuring device. In this case, the measurement conditions are as follows.
0.5%, STATIC STRAIN: 1.0%, frequency: 1 Hz. Note that the measurement conditions are not limited to those described above, and can be set to optimal conditions according to the thickness of each layer, the size of the measurement sample, and the like.

As described above, the charging member of the present invention improves the durability by controlling the difference between the storage elastic modulus of each layer and the storage elastic modulus of the adjacent layer to 500 times or less. It is a thing. In this case, the reason why the durability is improved by controlling the difference in the storage elastic modulus of each layer in this way is not clear, but is considered as follows.

In order to prevent the residual toner from adhering to the surface of the charging member, it is conceivable to arrange a fluorine resin or the like having excellent antifouling properties on the surface of the charging member.
It is not enough to improve durability. Of course, application of a material with excellent antifouling properties such as fluororesin is effective,
In the case of a contact-type charging member as in the present invention, since the charging member is used by being pressed against the member to be charged, the charging member is always used in a deformed state, and the mechanical characteristics, especially the durability, Regarding, the repeated deformation behavior is important, not only the mere non-adhesion with the toner, but also the measures against repeated deformation are required, no matter how much material with excellent antifouling property is placed on the outermost surface, due to deformation during durability, If cracking, peeling, or the like occurs, toner will start to accumulate in that portion.

The charging member is usually formed of two or more layers, as typified by an elastic layer and a coating layer formed on the surface, and in this case, the bonding state of each layer is taken into consideration. Then, the charging member must be designed. Therefore, as in the present invention, the mechanical properties of each layer are controlled in consideration of the balance with the mechanical properties of an adjacent layer, and the durability is improved by minimizing adverse effects due to repeated deformation during durability. Seems to be able to.

The charging member of the present invention has the elastic layer 3, the outer layer 4 having a single layer structure or a multi-layer structure, and can be formed in a roller shape as shown in FIG. 1, for example.
Further, if necessary, another layer may be provided between the elastic layer 3 and the outer layer 4. For example, when the elastic layer 3 is formed using a polyurethane foam, an acrylic resin, a polyester resin, or the like is used in order to more effectively prevent noise generation when a voltage is applied and to improve the surface smoothness of the elastic layer 3. An intermediate layer in which a conductive agent is added to a base resin such as a polyurethane resin, a nylon resin, an epoxy resin, a urethane-modified acrylic resin, a butyral resin, a phenol resin, a vinylidene chloride-based copolymer, and a polyvinyl acetal resin may be provided. It is needless to say that this intermediate layer must also satisfy the condition of the storage elastic modulus (E ').

If the surface of the charging member has a high hardness or has irregularities, the toner is clogged and causes an image defect. Therefore, it is preferable that the surface of the member has a low hardness and is as smooth as possible. . Specifically, the surface hardness is
The micro hardness is preferably 80 degrees or less, particularly preferably 75 degrees or less, and the surface smoothness is determined by JIS 10 point average roughness Rz.
Is preferably 4 μm or less, particularly 3 μm or less, and more preferably 2 μm or less.

The charging member of the present invention is disposed in contact with a member to be charged, such as a photosensitive drum, and by applying a voltage between the member to be charged and the charging member of the present invention, the member to be charged is applied. In this case, the voltage applied between the charging member and the member to be charged may be a DC voltage or an AC voltage, and is not particularly limited.
It is preferable to perform charging by applying a voltage in which an AC voltage is superimposed on a DC voltage, so that the member to be charged can be charged more uniformly. Although not particularly limited, the contact pressure between the charging member of the present invention and the member to be charged is 50 to 2000 g, particularly 100 to 1000 g.
It is preferable to obtain favorable charging.

With respect to a charging device using the charging member of the present invention, for example, as shown in FIG.
To a member to be charged 5 such as a photosensitive drum at a predetermined pressure,
A charging device configured to apply a voltage between the voltage applying means 6 and the charged object 5 can be exemplified, but is not limited thereto.
The form and the voltage application method by the voltage application means 6 may be appropriately changed.

[0040]

According to the charging member of the present invention, it is possible to effectively prevent sticking of the residual toner, obtain good durability, and exhibit stable performance for a long period of time. Therefore, according to the charging device using the charging member of the present invention, a favorable charging operation can be stably performed over a long period of time.

[0041]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following.

Example 1 A metal shaft having a thickness of 30
An elastic layer A having a thickness of 2,000 μm is formed thereon.
Is formed, and a coating layer B having a thickness of 6 μm is further formed thereon. An outer layer having a two-layer structure including the coating layer A and the coating layer B is formed outside the elastic layer A. A charging roller (charging member) having the above was prepared. Elastic layer A, coating layer A and coating layer B
Is as follows. The surface roughness of the obtained charging roller was 0.6 μm in JIS 10-point average roughness Rz, and the micro hardness was 76 degrees.

Elastic Layer A A urethane foam having a density of 0.5 g / cm ³ made by adding carbon to a polyester polyol or isocyanate, and having a storage elastic modulus (E ′) of 7.5 × 10 ⁶ dy.
n / cm ² . Was formed by coating the coating layer A water-based acrylic resin coating material was added carbon, a coating layer having an adjusted volume resistivity of the 6 × 10 ⁷ Ωcm, storage elastic modulus (E ') is 2.1 × 1
It was 0 ⁸ dyn / cm ^2. Coating layer B water-dispersed fluororesin, vinylidene chloride copolymer latex, formed by applying a paint to which carbon is added to a resin blended with polyvinyl acetal resin,
It is a coating layer having a volume resistivity adjusted to 7.1 × 10 ⁷ Ωcm, and has a storage elastic modulus (E ′) of 4.0 × 10 ⁹ dyn /
cm ² . Note that carbon has an oxygen content of 10
% And a pH of 7.33 were used.

When the obtained charging roller was mounted on a printer and an image was formed, a good image was obtained. Furthermore, no abnormalities in the image occurred even when 6,000 continuous images were output.

Example 2 Example 1 on a metal shaft
An elastic layer A having a thickness of 3000 μm is formed in the same manner as described above, a coating layer C having a thickness of 150 μm is formed thereon, and a coating layer D having a thickness of 10 μm is further formed thereon. A charging roller (charging member) having a two-layer outer layer composed of a coating layer C and a coating layer D on the outside was prepared. The coating layer C and the coating layer D are as follows. The surface roughness of the obtained charging roller was 0.9 μm in terms of JIS 10-point average roughness Rz, and the micro hardness was 71 degrees.

Coating layer C A coating layer formed by applying a coating material obtained by adding carbon to an aqueous urethane resin and having a volume resistivity adjusted to 7 × 10 ⁷ Ωcm, and having a storage elastic modulus (E ′) of 9.7 × 1
It was 0 ⁷ dyn / cm ^2. Coating layer D A coating layer formed by applying a coating material in which carbon is added to a resin in which a water-dispersible fluororesin and a polyvinyl acetal resin are blended, and having a volume resistivity adjusted to 4.1 × 10 ⁷ Ωcm. , Storage elastic modulus (E ′) is 1.0 × 1
0 was ⁹ dyn / cm ^2, Note, carbon 10% oxygen content, pH was used as a 7.33.

When the obtained charging roller was mounted on a printer and an image was formed, a good image was obtained. Furthermore, no abnormalities in the image occurred even when 6,000 images were continuously output.

Comparative Example 1 The coating layer A was replaced with the coating layer E,
Example 1 was repeated except that the coating layer B was replaced with the coating layer F.
A charging roller was prepared in the same manner as described above. The coating layer E and the coating layer F are as follows. The surface roughness of the obtained charging roller was 1.1 μm in JIS 10-point average roughness Rz, and the micro hardness was 87 degrees.

[0049] was formed by coating a coating material obtained by adding carbon to the coating layer E urethane resin, a coating layer having an adjusted volume resistivity of the 8 × 10 ⁷ Ωcm, storage elastic modulus (E ') is 5 × 10 ⁷ dy
n / cm ² . Was formed by coating a coating layer F acrylic paint with added carbon, a coating layer having an adjusted volume resistivity 4 × 10 ⁷ Ωcm, the storage modulus (E ') is 4 × 10 ¹⁰ dy
n / cm ² .

When the obtained charging roller was mounted on a printer and an image was formed, a good image was obtained in the initial stage.
From around 400 sheets, dot-like defects occurred in the image, and when the roller was observed, the toner had bitten into the surface.

Comparative Example 2 A charging roller was prepared in the same manner as in Example 1 except that the coating layer B was formed directly on the elastic layer A without forming the coating layer A. The surface roughness of the obtained charging roller was 0.8 μm in JIS 10-point average roughness Rz,
The micro hardness was 70.1 degrees.

When the obtained charging roller was mounted on a printer and an image was formed, a good image was obtained in the initial stage.
From around 200 sheets, dot-like defects occurred in the image, and when the roller was observed, the toner had bitten into the surface.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of the charging member of the present invention.

FIG. 2 is a schematic view showing an example of the charging device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charging member 2 Shaft 3 Elastic layer 4 Outer layer 5 Charged body 6 Voltage applying means

Claims (9)

[Claims] 1. A charging member for charging a member to be charged by applying a voltage between the member and a member to be charged by contacting the member with the member. Or a ratio of the storage elastic modulus (E ') of each layer to the storage elastic modulus (E') of an adjacent layer having one or more outer layers formed via another layer. A charging member, wherein the difference is within 500 times. 2. The charging member according to claim 1, wherein said outer layer comprises one or more coating films. 3. A storage elastic modulus (E ′) of the elastic layer is 5 ×.
The charging member according to claim 1, wherein the charging rate is 10 ⁷ dyn / cm ² or less. 4. The charging member according to claim 1, wherein each of the layers constituting the outer layer has a storage elastic modulus (E ′) of 2.5 × 10 ¹⁰ dyn / cm ² or less. . 5. The charging member according to claim 1, wherein the micro hardness of the member surface is 80 degrees or less. 6. The charging member according to claim 1, wherein a JIS 10 point average roughness Rz of the member surface is 4 μm or less. 7. The elastic layer has a density of 0.05 to 0.9 g.
The charging member according to any one of claims 1 to 6, wherein the charging member is a urethane foam having a density of / cm ³ . 8. The outer layer is composed of two or more layers, and the outermost layer is a layer containing an aqueous fluororesin having an oxygen content of 5% or more and a pH of 5 or more to which carbon is added. The charging member according to any one of the above. 9. A charging device, comprising: a charging member that contacts a member to be charged and charges the member to be charged; and voltage applying means that applies a voltage between the member to be charged and the charging member. A charging device using the charging member according to claim 1 as the charging member.