JPH10319676A - Electrifying member and electrifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying member which hardly causes compressive deformation and can decrease the noise during electrification. SOLUTION: The member 1 is used by bringing into contact with a body to be electrified and by applying voltage on the body to electrify. The member has an elastic layer 4 and a coating layer 4 directly on the outer surface of the elastic layer 3 or with another layer interposed. The coating layer 4 has <=1×10<7> dyn/cm<2> storage elastic modulus (G') and 0.01 to 0.04 tanδ as the ratio of the loss elastic modulus (G") to the storage elastic modulus (G').

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 a charging device suitably used for charging an object to be charged such as a photosensitive member in an electrostatic latent image process in a copying machine, a printer or the like.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, first, the surface of a photoreceptor is uniformly charged, and an image is projected on the photoreceptor from an optical system so that a portion of the photoreceptor exposed to light is exposed. An electrostatic latent image is obtained by an electrostatic latent image process of forming a latent image by erasing the charge, and then printing is performed by forming a toner image by attaching toner and transferring the toner image to a recording medium such as paper. The method has been taken.

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. Also, ozone,
Since harmful substances such as NO _x is generated, there are also environmental issues.

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

In this case, as a charging member used in this contact charging method, for example, a resin solution in which a resin such as urethane or nylon is dissolved in an organic solvent is dipped on the surface of an elastic layer such as rubber or urethane foam. It is known that a coating layer such as urethane or nylon is formed by applying the toner by a spraying method or the like to secure the smoothness of the surface and prevent the adhesion of the toner.

[0006]

However, in this contact charging system, the charging member is in a state of being pressed against a member to be charged such as a photoreceptor for a long time, so that the charging member is likely to be deformed. If it does not return, an image defect will occur. For this reason, it is required that the elastic body and the coating film constituting the charging member have a small compression set.

In the contact charging method, a method of superimposing an AC voltage on a DC voltage is often used in order to stably maintain a uniform charging potential of a member to be charged. When an AC voltage is applied in the contact state, the AC voltage causes a phenomenon in which the charging member hits the member to be charged, and noise is generated. To prevent this, it is required to lower the hardness of the charging member.

In this case, the compression set of the charging member can be reduced by increasing the elasticity of the coating film by, for example, crosslinking the resin forming the coating film. When the resin is crosslinked, inconveniences such as an increase in the hardness of the coating film, an increase in noise, and a problem in that the surface of a member to be charged such as a photoreceptor that is in direct contact with the coating film are liable to occur.

On the other hand, in order to lower the hardness of the charging member, there is a method of adding a plasticizer or a softener to a rubber material or a foam material for forming an elastic layer. In this case, bleeding of the added plasticizer or softener is performed. Is generated, and problems such as contamination of a charged body such as a photoreceptor occur.

As described above, it is difficult to achieve both low deformation and low hardness of the charging member, and to achieve low noise while maintaining excellent charging performance by the conventional measures.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a novel charging member that is less likely to undergo compressive deformation and can reduce charging noise, and a charging device using the charging member. The purpose is to do.

[0012]

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. In the charging member having one or two or more coating layers formed by adjusting the relationship between the storage elastic modulus (G ′) and the loss elastic modulus (G ″) of the coating layer, It has been found that compression deformation and generation of charging noise can be controlled, and as a result of further study, the storage elastic modulus (G ′) is 1 × 10 ^7.
dyn / cm ² or less, and tan δ represented by the ratio of the loss modulus (G ″) to the storage modulus (G ′) is 0.01 to
By forming the coating layer with a coating that is 0.4,
The present inventors have found that a charging member that hardly undergoes compression deformation and has low charging noise can be obtained, and the present invention has been completed.

More specifically, the tan δ is represented by the ratio tan δ = G ″ / G ′ between the loss modulus (G ″) and the storage modulus (G ′) as described above. Shows the ratio between viscous and elastic properties. Therefore, in the resin material forming the coating film layer, the fact that the tan δ is large means that the contribution of the viscosity is increased, so that the compression set is increased and the deformation amount of the charging member is increased.
On the other hand, a small tan δ means that the contribution of elasticity is large and the amount of deformation is small, but the noise when voltage is applied is large. In this case, it is ideal that the coating layer of the charging member is low in viscosity and low in elasticity, and tan δ and G ′ should have a suitable region close to this ideal. Therefore, the present inventors have conducted various studies in order to find these preferable ranges, and have found the preferable ranges of tan δ and G ′ as described above.

Therefore, according to the present invention, by applying a voltage to the member to be charged while contacting the member to be charged,
A charging member for charging an object to be charged has an elastic layer and a coating layer formed directly or via another layer outside the elastic layer, and the coating layer has a storage modulus (G ') Is 1x
Tan δ of not more than 10 ⁷ dyn / cm ² and represented by the ratio of the loss modulus (G ″) to the storage modulus (G ′) is 0.0
An object of the present invention is to provide a charging member comprising a coating film of 1 to 0.4.

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 a coating layer formed on the elastic layer, and its form can be stably contacted with the member to be charged. Any form may be used as long as it can uniformly apply electric charge to the layer to be charged, and for example, various forms such as a roll, a plate, a block, a sphere, and a brush can be used. Usually, it is preferable to form a roll. When formed into a roll, for example, as shown in FIG.
The charging member 1 in which the elastic layer 3 is formed on the outer periphery of the shaft 2 and the coating layer 4 is formed outside the elastic layer 3 can be exemplified. In this case, the shaft 2 may be a metal or plastic shaft, and may be omitted depending on the form of the charging member and the mechanism of the charging device using the charging member.

The elastic layer 3 is not particularly limited, and may be rubber, resin, or a foam thereof (hereinafter, referred to as a foam).
"Foam"), 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 foam density in this case is 0.0
About 5 to 0.9 g / cm ³ is appropriate.

A conductive agent is added to the elastic layer 3.
Thereby, a predetermined resistance value can be provided. Its guidance
The electric agent is not particularly limited, and lauryl trimethyl alcohol
Ammonium, stearyltrimethylammonium, octane
Tadodecyl trimethyl ammonium, dodecyl trimethyl
Luammonium, hexadecyltrimethylammonium
Of modified fatty acid and dimethylethylammonium salt
Borates, chlorates, borofluorides, sulfates, ethates
Sulfate salt, benzyl bromide salt, benzyl chloride salt, etc.
Cations such as quaternary ammonium salts such as benzyl halide salts
Ionic surfactant, aliphatic sulfonate, higher alcohol
Sulfuric acid ester, higher alcohol ethylene oxide
Sulfuric acid ester addition salt, higher alcohol phosphate ester
Salt, higher alcohol ethylene oxide added phosphate ester
Anionic surfactants such as sodium salts and amphoteric surfactants such as various betaines
On-surfactant, higher alcohol ethylene oxide,
Polyethylene glycol fatty acid ester, polyhydric alcohol
Antistatic agents such as nonionic antistatic agents such as fatty acid esters
Stopper, LiCF_ThreeSO_Three, NaClO_Four, LiAsF₆, L
iBF_Four, NaSCN, KSCN, NaCl, etc.⁺,
Na⁺, K⁺Metal salt of Group 1 of the Periodic Table, or NH
_Four ⁺Electrolytes such as salts, and Ca (ClO_Four)_TwoEtc. C
a²⁺ , Ba²⁺ Metal salts of the second group of the periodic table, such as
Has at least one or more hydroxyl groups, carbohydrates,
Isocyanates such as xyl groups and primary or secondary amine groups
With a group having active hydrogen that reacts with
You. Furthermore, 1,4-butanediol, ethyl and the like
Len glycol, polyethylene glycol, propylene
Polyhydric alcohols such as glycol and polyethylene glycol
Complexes of ethylene glycol and its derivatives or ethylene glycol
Nomethyl ether, ethylene glycol monoethyl ether
Ionic conductive agents such as complexes with monols such as
Conductivity such as Tetjen Black EC and acetylene black
Carbon, SAF, ISAF, HAF, FEF, GP
Rubber carbon such as F, SRF, FT, MT, etc., oxidation treatment
Color (ink) carbon and pyrolysis carbo
, Natural graphite, artificial graphite, antimony
Doped tin oxide, titanium oxide, zinc oxide, nickel,
Metals such as copper, silver, germanium and metal oxides, polya
Conductive poly such as nilin, polypyrrole, polyacetylene
And the like. In this case, the amount of these conductive agents
Is appropriately selected according to the type of the composition.
Has a volume resistivity of 10⁰-10⁸Ω · cm, preferably 10
^Two-10⁶It is adjusted to be Ω · cm.

Next, the coating layer 4 is a coating film having the above-mentioned storage modulus (G ') and tan δ, and is usually formed of a resin to which a conductive agent is added. In this case, any resin can be used as a resin for forming the coating film as long as it can add a conductive agent, and is not particularly limited. When forming, an aqueous resin is preferably used to ensure smoothness. 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 water-based resins include polyester-based, acrylic-based, urethane-based, and hot-water-soluble resins such as polydioxolane.Acrylic resins are generally used as resins for charging members. Since the dielectric constant is much smaller than urethane or nylon, which has been used for a long time, the capacitance is also small.
It is particularly preferably used because repulsion is reduced and charging noise can be reduced.

In this case, the acrylic resin is not particularly limited, but has a glass transition temperature of -60 to 20 ° C.
Preferably, a temperature of -50 to 10C is suitably used.
That is, those having a glass transition temperature of more than 20 ° C. can form a coating film on the elastic layer 3, but are liable to be easily cracked or the like at the time of charging operation, which may not be practical. On the other hand, those having a glass transition temperature lower than −60 ° C. have good flexibility but strong adhesion, and are practically used due to problems in workability in forming a coating film and compatibility with a general photoreceptor as a member to be charged. Not very good.

The acrylic resin includes a thermoplastic type and a cross-linked type such as self-crosslinking, melamine cross-linking, and isocyanate cross-linking. Can be suitably used,
Although not particularly limited, a thermoplastic type is particularly preferably used from the viewpoint of a coating film forming step and hardness.

The coating layer 4 can be provided or adjusted with conductivity by adding a conductive agent, and usually has a volume resistivity of 10 ³ to 10 ¹² Ωcm, particularly 10 ⁵ to 10 ¹⁰ Ωcm. It is preferable to adjust as follows. In this case, as the conductive agent, the same conductive agent as that exemplified in the elastic layer 3 can be exemplified, but carbon is particularly preferably used. The amount of the conductive agent to be added is appropriately selected depending on the type of the conductive agent and the like so as to have the above volume resistivity, and is not particularly limited. To 60% by weight, especially about 10 to 40% by weight.

Further, appropriate additives such as a thickener, a thixotropy-imparting agent, and a structural viscosity-imparting agent can be added to the coating layer 4 as needed. The additive may be either inorganic or organic.

The thickness of the coating 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, more preferably 800 μm. Hereinafter, it is particularly preferable to set the thickness to 20 to 600 μm.

As described above, this coating layer 4 has a storage elastic modulus (G ') of 1 × 10 ⁷ dyn / cm ² or less, and has a loss elastic modulus (G ″) and a storage elastic modulus (G ′). Tan δ expressed by a ratio of 0.01 to 0.4, preferably G ′ is 1 × 10 ⁶ to 1 × 10 ⁷ dyn / cm ² ,
δ is 0.1 to 0.4. As a result, a charging member that hardly undergoes compression deformation and has low charging noise can be obtained.

Here, G ′ and tan δ can be obtained as follows. First, a film is formed from the coating material for forming the coating film 4, and a sample having a diameter of 10 mm and a thickness of 1 mm cut out from the film is prepared. Next, this sample was mounted on a viscoelasticity measuring apparatus, and the viscoelasticity was measured at a measurement temperature of 40 ° C., a frequency of 0.05 Hz, and a strain of 5%.
Ask for. As the viscoelasticity measuring device, Reo
Metrics RECAP II (Rheometrics) can be used.

Although not shown in FIG. 1, the charging member of the present invention may further include one more layer on the coating layer 4 in accordance with the purpose of preventing toner adhesion and ensuring surface smoothness. Or 2
More than one outer layer can be provided.

The outer layer 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. 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.

The outer layer can 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, nylon resin, epoxy resin, vinylidene chloride copolymer, etc. The outer layer can be formed by mixing two or more kinds with the fluororesin. Among these resins, polyvinyl acetal resin, urethane resin, polyester resin, and vinylidene chloride copolymer are preferable, and polyvinyl acetal resin is particularly preferably used, from the viewpoint of forming a coating film and uniform resistance of the fluororesin.

The outer layer can be provided or adjusted with a conductive agent by adding a conductive agent. In this case, the conductive agent is not particularly limited, but carbon is preferably used. It is preferable to use carbon as a conductive agent for the outermost layer that forms the surface of the substrate. In this case, the carbon used for the outer layer is not particularly limited, but has an oxygen content of 5% or more, particularly 7%.
% Or more, more preferably 9% or more, and p
H is preferably 5 or more, particularly 6 or more, and more preferably 7 or more. That is, the oxygen content of ordinary carbon is 0.1 to
It is about 3%, and there is a part of carbon which has been oxidized. However, the carbon which has been oxidized tends to shift its pH to an acidic side as the oxygen content increases slightly. If the carbon becomes acidic, the stability may decrease when added to the 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. . Such oxygen content and p
Although the detailed structure of the carbon having H is not clear,
It is preferable to use a carbon surface in which functional groups such as a carboxyl group, a hydroxyl group, and a ketone group are provided, and a part of hydrogen contained in these functional groups is substituted with an alkali metal such as sodium.

The amount of the conductive agent to be added can be appropriately adjusted so as to obtain a desired resistance. in this case,
The resistance of the outer layer is preferably set to a volume resistivity of 10 ³ to 10 ¹² Ω · cm, particularly preferably 10 ⁵ to 10 ¹⁰ Ω · cm, and the amount of the conductive agent added is adjusted so as to achieve such a volume resistivity. When carbon is used as the conductive agent, the amount of addition is usually about 0.01 to 40% by weight, particularly about 5 to 20% by weight of the outer layer.

To the outer layer, as in the case of the coating layer 4, an appropriate additive such as a thickener, a thixotropy-imparting agent, or a structural viscosity-imparting agent is added, if necessary, in an appropriate amount. In this case, the additives may be either inorganic or organic.

Although the thickness of the outer layer is not particularly limited, it is preferably 30 μm or less, particularly preferably 5 to 15 μm. If the thickness of the outer layer exceeds 30 μm, the outer layer becomes hard and the flexibility becomes low. It may be damaged, and the durability may be reduced, which may cause cracks due to use.

The method of forming the coating layer 4 and, if necessary, the outer layer formed on the coating layer 4 is not particularly limited. A method of preparing and applying this paint by dipping or spraying is preferably used.

The charging member of the present invention has the elastic layer 3, the coating layer 4, and the outer layer provided as needed, and can be formed into a roller shape as shown in FIG. 1, for example. However, if necessary, another layer may be provided between the elastic layer 3 and the coating 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. In the present invention, even if such an intermediate layer is omitted, generation of noise is effectively suppressed by the function of the coating layer, and good silence is obtained.

The resistance value of the member of the charging member of the present invention is appropriately selected according to the charging device to be mounted and the member to be charged, and is not particularly limited. The resistance is preferably from 10 ² to 10 ¹² Ω · cm, particularly preferably from 10 ⁵ to 10 ¹⁰ Ω · cm.

Although the charging member of the present invention is not particularly limited, its electrostatic capacity is 1 × 10 ⁻⁹ F or less, particularly 8 × 10 ⁻¹⁰ F or less, furthermore 6 × 10 ⁻¹⁰ F. F or less, whereby the generation of noise during the charging operation can be more effectively suppressed. In this case, the capacitance can be determined by, for example, a measuring method using an impedance analyzer measuring instrument, an electric measurement on a metal drum, or the like.

The method of measuring the capacitance will be described in detail.
First, measurement with an impedance analyzer, for example, in the case of a roll-shaped charging member, press the roll-shaped charging member against a highly conductive plate or drum of metal or the like, and place an impedance analyzer measuring device between the roll and the highly conductive plate or drum Is connected, and the capacitance is calculated by an impedance analyzer.

The electrical measurement on the metal drum is a method of calculating the capacitance assuming that the charging member is operating in a printer, a copying machine, or the like. For example, in the case of a roll-shaped charging member, the metal drum and the roll are rotated while being pressed against each other, and a voltage is applied between the two members that rotate in the pressed state under predetermined conditions. In this case, the predetermined condition is substantially the same condition as the voltage applied to the charging member in a printer or a copier. For example, in the case of an organic photosensitive drum, the charging potential is often about -700 V. In order to replenish the charge, a DC current of about 7 μA flows through the roll, and a DC resistance can be obtained by flowing this current to the metal drum. In addition, there are printers and copiers of the type that allow AC current to flow to keep the charging potential uniform.
The AC current is controlled at a constant current, and the AC current can be obtained by flowing the AC current to a metal drum. Therefore, the capacitance can be calculated by substituting the DC resistance value and the AC resistance value for the roll circuit model as a parallel model of the DC resistance component and the capacitance component.

Further, if the surface of the charging member has irregularities, the toner may be clogged in the concave portion, which may cause an image defect. Therefore, the surface of the member is preferably as smooth as possible. 4 μm in point average roughness Rz
Hereinafter, it is particularly preferable that the thickness be 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 a voltage is applied between the member to be charged and the charging member of the present invention to thereby form a member to be charged. 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.

As for the charging device using the charging member of the present invention, for example, as shown in FIG.
A charging device configured to contact the object to be charged 5 such as a photosensitive drum and apply a voltage between the voltage applying means 6 and the object to be charged 5, but is not limited thereto. However, the form of the member to be charged 5 and the charging member 1 and the method of applying a voltage by the voltage applying means 6 may be appropriately changed.

[0043]

According to the charging member of the present invention, when the charging operation is performed by the contact charging method, deformation is unlikely to occur, and image defects due to deformation can be prevented as much as possible, and noise can be prevented. Can be effectively prevented. Therefore, according to the charging device using the charging member of the present invention, it is possible to stably perform a good charging operation for a long period of time without generating inconveniences such as generation of noise and scraping of a member to be charged. It is.

[0044]

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

Example 1 Conductive urethane foam
(Density 0.48g / cm^Three ) On the surface of the elastic layer,
A coating layer A having a thickness of 300 μm is formed, and the surface of the coating layer A is formed.
Then, an outer layer B having a thickness of 10 μm is formed to form a charging roller.
Done. The coating layer A and the outer layer B are as follows.
is there. The surface roughness of the obtained charging roller is JIS 10 point flat.
Average roughness Rz 0.3 μm, hardness (JIS-A) 57 °
And the capacitance is 4 × 10^-TenF. In addition,
The capacitance was obtained by pressing the obtained roller against the metal drum.
When rotating in the state and applying a direct current of 7μA between them
The DC resistance value is obtained from the DC voltage of
Measure the AC voltage when 60μA is applied,
Calculated as a parallel model of DC resistance component and capacitance component
(The same applies to the following examples).

[0046] The coating layer A in an aqueous acrylic resin having a carboxyl group, formed by applying a coating material was added paint with added carbon and epoxy crosslinking agent, a volume resistivity of 5 × 10 ⁷ Ω
cm. This coating film has a storage elastic modulus (G ′) of 6 ×
At 10 ⁶ dyn / cm ² , tan δ was 0.23. Outer layer B was molded by applying a coating material in which carbon was added to a resin obtained by blending a water-dispersible fluororesin, a vinylidene chloride-based copolymer latex, and a polyvinyl acetal resin, and the volume resistivity was adjusted to 5 × 10 ⁷ Ωcm. . In addition,
As the carbon, one having an oxygen content of 10% and a pH of 7.33 was used.

The obtained charging roller was mounted on a printer, and an image was formed at a temperature of 15 ° C. and a humidity of 10% RH. As a result, a good image was obtained. Was not seen.

The charging roller is pressed against the photoreceptor and rotated, so that the DC voltage is -7.0 kV and the AC voltage Vpp2.
A charging operation was performed by applying a voltage superimposed on 0 kV (frequency 500 Hz), and the noise at this time was measured. As a result, the magnitude of the noise was 50 dB, and there was no particular problem.

Further, a load of 500 g was applied to both ends of the charging roller, and the charging roller was brought into contact with the photoreceptor at a pressure of 1000 g, left at 50 ° C. and 95 RH for 3 days. When the dent amount of the contact portion was measured using a laser outer diameter measuring device (manufactured by Mitutoyo Corporation), the deformation amount was 20 μm. Did not occur.

[Embodiment 2] An elastic layer made of the same conductive urethane foam as in Embodiment 1 was formed on the surface of an elastic layer having a thickness of 300 μm.
Was formed, and an outer layer B similar to that of Example 1 was formed on the surface of the coating film layer C to prepare a charging roller. The coating layer C is as follows. The surface roughness of the obtained charging roller was 0.3 μm in JIS 10-point average roughness Rz, the hardness (JIS-A) was 65 °, and the capacitance was 5 × 10
It was ^-10 F.

Coating layer C The coating layer was formed by applying a coating material in which carbon and an oxazoline crosslinking agent were added to an aqueous acrylic resin having a carboxyl group similar to that of coating layer A, and had a volume resistivity of 5 × 1.
It was adjusted to 0 ⁷ Ω · cm. This coating film has a storage elastic modulus (G ') of 1 × 10 ⁷ dyn / cm ² and a tan δ of 0.1.
33.

When the obtained charging roller was mounted on a printer and an image was formed in the same manner as in Example 1, a good image was obtained. Even when 6,000 continuous images were formed, no image deterioration was observed. Was. When the noise was measured in the same manner as in Example 1, the magnitude of the noise was 55 dB, and there was no particular problem. Further, when a pressure contact test was performed in the same manner as in Example 1, the amount of deformation was 25 μm.
In particular, no image defects occurred.

[Comparative Example 1] A 300 μm thick layer was formed on the surface of an elastic layer made of the same conductive urethane foam as in Example 1.
Is formed on the surface of the coating layer D.
An outer layer B was formed in the same manner as described above to prepare a charging roller. The coating layer D is as follows. The surface roughness of the obtained charging roller was 0.3 μm in JIS 10-point average roughness Rz,
Hardness (JIS-A) is 70 ° and capacitance is 4 × 1
It was 0 ^-10 F.

Coating layer D The coating layer was formed by applying a paint containing only carbon to an aqueous acrylic resin having a carboxyl group similar to that of coating layer A, and the volume resistivity was adjusted to 5 × 10 ⁷ Ωcm. This coating film has a storage elastic modulus (G ′) of 3 × 10 ⁷ dyn.
/ Cm ² and tan δ was 0.45.

When the obtained charging roller was attached to a printer and an image was formed in the same manner as in Example 1, a good image was obtained. Even when 6,000 continuous images were formed, deterioration of the image was almost observed. Did not. When the noise was measured in the same manner as in Example 1, the magnitude of the noise was 60
dB, and there was no particular problem. However, when a pressure welding test was performed in the same manner as in Example 1, the deformation amount was 50 μm.
When the roller after the test was mounted on a printer and an image was displayed, horizontal stripes were generated on the halftone screen due to deformation of the charging roller.

[Comparative Example 2] A 300 μm thick layer was formed on the surface of an elastic layer made of the same conductive urethane foam as in Example 1.
Is formed on the surface of the coating film layer E,
An outer layer B was formed in the same manner as described above to prepare a charging roller. The surface roughness of the obtained charging roller is JIS 10 point average roughness R
0.3 μm in z, hardness (JIS-A) is 75 °,
The capacitance was 5 × 10 ⁻¹⁰ F.

Coating layer E is formed by applying a paint containing carbon to a water-dispersible urethane resin, and has a volume resistivity of 5 × 10 ⁷ Ωc.
m. This coating film has a storage elastic modulus (G ′) of 3 × 1
In 0 ⁷ dyn / cm ^2, tanδ was 0.15.

When the obtained charging roller was mounted on a printer and an image was formed in the same manner as in Example 1, a good image was obtained. Even when 6,000 continuous images were formed, the image was hardly degraded. Did not. When noise was measured in the same manner as in Example 1, the noise level was 70
dB, and high frequency noise was generated. Further, when a pressure welding test was performed in the same manner as in Example 1, the deformation amount was 15
When the roller after the test was mounted on a printer and an image was displayed, no image defect was particularly generated.

[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 Coating layer 5 Charged body 6 Voltage applying means

Claims (7)

[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 coating layer formed via another layer, wherein the coating layer has a storage elastic modulus (G ′) of 1 × 10 ⁷ dyn / cm ² or less and a loss elastic modulus (G ″). ) And the storage modulus (G ′)
A charging member comprising a coating film having an δ of 0.01 to 0.4. 2. The charging member according to claim 1, wherein the capacitance is 1 × 10 ⁻⁹ F or less. 3. The charging member according to claim 1, wherein the coating layer includes a layer containing an acrylic resin. 4. The method according to claim 1, wherein the outermost layer has a coating containing an aqueous fluororesin having an oxygen content of 5% or more and a pH of 5 or more added to the coating layer.
The charging member according to any one of claims 1 to 3. 5. The charging member according to claim 1, wherein the member surface has a JIS 10-point average roughness Rz of 4 μm or less. 6. The elastic layer has a density of 0.05 to 0.9 g.
The charging member according to any one of claims 1 to 5, wherein the charging member is formed using a polyurethane foam having a thickness of / cm ³ . 7. A charging apparatus comprising: a charging member that contacts a member to be charged and charges the member; and voltage applying means that applies a voltage between the member and the charging member. A charging device, wherein the charging member according to claim 1 is used as the charging member.