JP2001215775A - Electrifying member and electrifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying member having excellent surface smoothness which does not cause image failures even at high temperature and high humidity or at low temperature and low humidity even when the member is used for an electrostatic latent image process in a copying machine, printer or the like, and to provide an electrifying device which uses the electrifying member. SOLUTION: In the electrifying member to electrify the objective body to be electrified by bringing the member into contact with the objective body and applying a voltage between the member and the body, the electrifying member has an elastic layer and a coating film layer formed directly on the outer face of the elastic layer or with another layer interposed. The coating film layer is formed from a mixture of a water-based fluorocarbon resin crosslinked with melamine resin, a water-based urethane resin and polytetrafluoroethylene fine particles. The image forming device uses the aforementioned electrifying member.

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 photoreceptor in an electrostatic latent image process in a copying machine, a facsimile, a printer or the like.

[0002]

2. Description of the Related Art In an electrophotographic apparatus such as a copying machine, a facsimile, a printer, or an electrostatic recording apparatus, first, the surface of a photoconductor is uniformly charged, and an image is projected on the photoconductor from an optical system. An electrostatic latent image is formed by an electrostatic latent image process that forms a latent image by erasing the charge of the light-exposed portion, then forms a toner image by attaching toner, and a toner image on a recording medium such as paper. The method of printing is performed by transferring the image. In this case, a corona discharge method has conventionally been generally used for charging the photoconductor. However, since the corona discharge method requires application of a high voltage of 6 to 10 kV, it is not preferable from the viewpoint of safety maintenance of the machine. In addition, since harmful substances such as ozone and NOx are generated during corona discharge, there is also an environmental problem.

[0003] For this reason, charging schemes that can perform charging with an applied voltage lower than that of corona discharge and that can suppress 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. Examples of the charging member used in the contact charging method include, for example, a resin solution in which a resin such as acrylic, urethane, or nylon is dissolved in an organic solvent, on a surface of an elastic layer made of rubber or urethane foam, or a dipping method. It is known that a coating film layer of such a resin is formed by coating by a spray method or the like to ensure surface smoothness and prevent toner adhesion.
・

[0004]

However, when a resin solution obtained by dissolving the above resin in an organic solvent is applied to form the coating layer, an elastic body such as rubber or urethane foam forming the elastic layer is formed by the organic solvent. Swelling causes unevenness on the surface, making it difficult to ensure smoothness on the surface. As a means for preventing this, there is a method of forming a coating film layer using an aqueous paint. However, in this method, the coating film layer becomes hydrophilic and easily wets with water. Below, the coating layer swells or partially dissolves due to moisture, and the surface becomes non-uniform, which causes a problem of causing image defects. In order to prevent swelling or dissolution of the coating layer, a highly water-repellent fluororesin is preferably used as a resin for forming the coating layer, but originally, since the fluororesin has a high electronegativity, it is charged to a negative potential. easy. Therefore, when the charging member containing the fluororesin and the member to be charged for negative potential charging are left in contact, the charging member is likely to be charged to a negative potential and the member to be charged is likely to be charged to a positive potential. For this reason, after the charged member and the member to be charged are left in contact with each other under a low-temperature and low-humidity condition in which the stored charge is difficult to escape, a voltage is applied between the charging member and the member to be charged to apply a negative potential to the member. Even if you try to charge
The contact portion with the charging member on the surface of the member to be charged, due to the charge that has been unevenly distributed and stored during the contact and standing, does not reach a desired charging potential. I will. The present invention has been made in view of the above circumstances. That is, the present invention is a charging member that is excellent in surface smoothness and does not cause image defects in any environment such as high temperature, high humidity, and low temperature and low humidity even when used in an electrostatic latent image process in a copying machine, a facsimile, a printer, and the like. And a charging device using the charging member.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a coating layer having a specific property using an aqueous resin is formed outside the elastic layer. Due to the member, the elastic layer has excellent surface smoothness without swelling, the water resistance of the coating film is improved, no image failure due to dissolution of the coating film even under high temperature and high humidity, and the negative charging of the charging member It has been found that a charging member which does not cause an image defect due to a charging memory even under low temperature and low humidity can be obtained because the property is suppressed, and the present invention has been completed.

That is, according to the present invention, by bringing a member into contact with a member to be charged and applying a voltage between the member and the member to be charged,
In a charging member for charging an object to be charged, an elastic layer and a coating layer formed directly or via another layer outside the elastic layer, and the coating layer is cross-linked by a melamine resin A charging member formed from a mixture of an aqueous fluororesin or an aqueous urethane resin and fine particles of polytetrafluoroethylene; a charging member that abuts against the charged member and charges the charged member; and a charged member. A charging device comprising a voltage applying means for applying a voltage between the charging member and the charging member, wherein the charging member of the present invention is used as the charging member.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION 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 outside the elastic layer. Any form can be used as long as it can make stable contact with the member to be charged and can uniformly apply a charge to the layer to be charged by applying a voltage. Shape, plate shape, block shape,
Various shapes such as a sphere and a brush can be used,
Usually, it is preferable to form a roll. For example, as shown in FIG. 1, 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 on the outer side of the elastic layer 3 is illustrated in the case of forming a roll. be able to. In this case, a shaft made of metal or plastic can be used as the shaft 2, and the shaft 2 can be omitted depending on the form of the charging member, the mechanism of the charging device in which the charging member is used, and the like.

The elastic layer 3 is not particularly limited, and may be rubber, resin, or a foam thereof (hereinafter, referred to as a rubber or resin).
"Foam"), specifically, polyurethane, silicone rubber, butadiene rubber,
Rubber compositions using isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber, and the like as a base rubber are exemplified, but in the present invention, Particularly, polyurethane is preferable, and polyurethane foam having a foaming ratio of 1.5 to 50 is more preferably used. In this case, the foam density is suitably about 0.05 to 0.9 g / cm ³ .
A predetermined resistance value can be given to the elastic layer 3 by adding a conductive agent.

The conductive agent is not particularly limited.
But, for example, lauryltrimethylammonium, stear
Riltrimethylammonium, octadodecyltrimethyl
Ammonium, dodecyltrimethylammonium, f
Xadecyl trimethyl ammonium, modified fatty acid
Tyl ethyl ammonium perchlorate, chlorate, borate
Hydrofluoric acid, sulfate, ethosulfate, bromide
Benzyl halide salts such as benzyl salts and benzyl chloride salts
Cationic surfactants such as quaternary ammonium salts, fats
Aliphatic sulfonate, higher alcohol sulfate, high
Secondary alcohol ethylene oxide addition sulfate ester salt,
Higher alcohol phosphate ester, higher alcohol ethyl
Surface activity of oxide-added phosphate ester salts
Agents, zwitterionic surfactants such as various betaines,
Coal ethylene oxide, polyethylene glycol fat
Non-a such as fatty acid esters and polyhydric alcohol fatty acid esters
Antistatic agent such as ON-type antistatic agent, LiCF_ThreeSO_Three,
NaClO_Four, LiAsF ₆, LiBF_Four, NaSC
Li such as N, KSCN, NaCl⁺, Na⁺, K⁺Etc.
Group 1 metal salt of the periodic table, or NH_Four ⁺Electrolysis of salt etc.
Quality and Ca (ClO_Four)_TwoCa such as²⁺, Ba²⁺Etc.
Group 2 metal salts of the Periodic Table, and at least one
More than one hydroxyl group, carboxyl group, primary or secondary amino
Groups having active hydrogen that reacts with isocyanates such as
With 1,4-butanediol, ethylene glycol
Coal, polyethylene glycol, propylene glycol
And polyhydric alcohols such as polyethylene glycol
Complexes such as derivatives or ethylene glycol monomethyl
Ether, ethylene glycol monoethyl ether, etc.
Ionic conductive agent such as complex with monool, or Ketjen
Conductive carbs such as black EC and acetylene black
, SAF, ISAF, HAF, FEF, GPF, SR
Rubber carbon such as F, FT, MT, etc., oxidized
Color (ink) carbon, pyrolytic carbon, natural
Graphite, artificial graphite, antimony-doped acid
Tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, gel
Metals such as manium and metal oxides, polyaniline, poly
Conductive polymers such as pyrrole and polyacetylene;
Can be

The amount of the above-mentioned conductive agent is appropriately selected according to the type of the composition. Usually, the volume resistivity of the elastic layer 3 is 1 × 10 ⁰ to 1 × 10 ⁸ Ω · cm, preferably 1 × 10 ⁸ Ω · cm. × 10
It is adjusted so as to be ² to 1 × 10 ⁶ Ω · cm. In the present invention, the coating layer 4 formed outside the elastic layer 3 is
It is formed from an aqueous fluororesin and an aqueous urethane resin crosslinked by a melamine resin.

The water-based resin (water-based fluororesin and water-based urethane resin) is not particularly limited as long as the solvent or medium is water, and can be used in any form such as a water-soluble type, an emulsion type, and a suspension type.
The molecular weight of the resin can be increased without increasing the viscosity of the paint,
An emulsion type is preferably used in that the formed coating film has excellent strength. As a method of emulsifying the resin, a method of emulsifying by adding a surfactant (forced emulsification type) and a method of emulsifying by introducing a hydrophilic functional group such as a carboxyl group or a hydroxyl group into the resin (self-emulsification) However, if a surfactant is present in the coating layer, there are problems such as a decrease in the contact angle and contamination of the photoreceptor. In the present invention, a self-emulsifying type is preferred. Used.

Among the aqueous resins forming the coating layer 4, an aqueous fluororesin is preferably used from the viewpoints of water repellency, low friction and the like. As the aqueous fluororesin, a tetrafluoroethylene-hexafluoropropylene copolymer, a fluoroethylene-vinyl ether copolymer, a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer,
Ethylene-tetrafluoroethylene copolymer, fluoroethylene-based copolymers such as ethylene-chlorotrifluoroethylene copolymer, and further include polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, and the like. An emulsion of a fluoroethylene-vinyl ether copolymer is preferably used from the viewpoint of the film-forming property and affinity with a pigment. The glass transition temperature Tg of the aqueous fluororesin is preferably from 20 to 50 ° C, particularly preferably from 30 to 40 ° C, from the viewpoint of film-forming properties at low temperatures. The content of the aqueous fluororesin in the coating layer 4 is preferably 20 to 60% by weight, and particularly preferably 30 to 40% by weight. If the content is less than 20% by weight, the contact angle of the coating layer with water becomes less than 100 °, and the object of the present invention is to improve the water resistance of the coating film and to dissolve even under high temperature and high humidity. There is a possibility that it becomes impossible to achieve points such as obtaining a difficult coating film and preventing image defects. Also,
If the content is more than 60% by weight, cracks and cracks are generated in the coating film, and it may be difficult to secure the smoothness of the coating film surface.

Here, the contact angle is, as shown in FIG.
A liquid L such as water is placed on the surface of the solid S to be measured.
Is dropped, the angle θ between the solid S surface and the liquid surface is referred to as
When θ is large, it means that it is hard to wet with water. The contact angle θ can be measured using a goniometer or other goniometer. In the present invention, the contact angle when water is dropped on the charging roller is measured using an image processing contact angle meter (for example, Kyowa Measurement is performed using Interface Science Co., Ltd., CA-X type), and the obtained value is used.

In the present invention, fine particles of polytetrafluoroethylene are used in order to secure the smoothness of the coating film and to lower the toner adhesion. There is no limitation on the method of adding the polytetrafluoroethylene fine particles to the coating film. However, in consideration of the dispersion stability of the fine particles, a dispersion type in which the polytetrafluoroethylene fine particles are previously dispersed in water is preferably used. The particle size of the polytetrafluoroethylene fine particles is not particularly limited, but is 5 μm or less, particularly 0.05 to 5 μm from the viewpoint of smoothness.
It is preferably 1 μm. The above-mentioned polytetrafluoroethylene fine particles contained in the coating layer 4 are contained in the coating layer 20.
It is preferably about 60% by weight. This content is 20
When the amount is less than the weight percentage, the toner adhesion increases, and the toner adheres to the surface of the charging member at the time of the endurance test by outputting thousands of sheets of images continuously, so that the image may be deteriorated. On the other hand, if the content is more than 60% by weight, the coating film becomes brittle, and cracks and cracks may occur during the above-mentioned durability test, and the image may be deteriorated.

An aqueous urethane resin among the aqueous resins forming the coating film layer 4 is preferably used from the viewpoint of improving the film forming property of the coating film and preventing the occurrence of cracks, cracks and the like. The water-based urethane resin has a glass transition temperature T from the viewpoint of film-forming properties at low temperatures.
g is preferably −50 to 0 ° C., and −40 to −1
0 ° C. is particularly preferred. The content of the aqueous urethane resin in the coating layer 4 is preferably 10 to 30% by weight,
10-20% by weight is particularly preferred. If the content is less than 10% by weight, cracks and cracks may occur in the coating film, and it may be difficult to ensure the smoothness of the coating film surface. Also,
If the content is more than 30% by weight, the hydrophilicity of the coating layer 4 increases, and the tackiness of the coating film surface increases, which may cause adhesion to the photoreceptor and contamination of the photoreceptor. .

As the cross-linking agent for cross-linking the water-based fluororesin and the water-based urethane resin, melamine resin is preferably used because of its excellent electron-donating property, to prevent the member to be charged from being charged to a positive potential. . Melamine resins include methylated melamine, butylated melamine, and methyl melamine.
Although butyl mixed etherified melamine and the like can be mentioned, in the present invention, it is necessary to dissolve in water, and therefore, methylated melamine is preferable.In order to further enhance water solubility, a part of the methoxymethyl group is a methylol group. And those substituted with a hydroxyl group are preferably used. Crosslinking of the water-based fluororesin and the water-based urethane resin is achieved by adding a melamine resin, and the amount of the addition is 5/1 ≦ (fluororesin + urethane resin) / melamine resin ≦ 200 in terms of solid content weight ratio. / 1 "is preferable.
Further, “10/1 ≦ (fluororesin + urethane resin) / melamine resin ≦ 100/1” is particularly preferable. If the addition amount is less than this range, charging of the member to be charged to a positive potential cannot be suppressed, and an image defect occurs due to a memory effect. On the other hand, if the amount is larger than the above range, the coating film becomes hard, and thus, a long-term use causes a defective image by shaving the member to be charged.

The coating layer 4 can be added or adjusted with conductivity by adding a conductive agent, and usually has a volume resistivity of 1 × 10 ³ to 1 × 10 ¹² Ω · cm, especially 1 × 10
It is preferable to adjust so as to be ⁵ to 1 × 10 ¹⁰ Ω · cm. In this case, as the conductive agent, the same conductive agent as that exemplified in the elastic layer 3 can be exemplified.
Particularly, carbon is preferably used. The addition amount of the conductive agent is appropriately selected so as to have the above-mentioned volume resistivity depending on the type of the conductive agent and the like, and is not particularly limited, but when carbon is used as the conductive agent, it is usually 0.01. ~ 4
0% by weight, especially about 5 to 20% by weight.

The type of carbon used as a conductive agent in the coating layer 4 is not particularly limited, but preferably has an oxygen content of 5% or more, more preferably 7% or more, and a pH of 7% or more. Is preferably 5 or more, more preferably 6 or more, and particularly preferably 7 or more. That is, the oxygen content of ordinary carbon is about 0.1 to 3%, and there is carbon partially oxidized. However, as the oxygen content increases, the carbon oxidized increases. The pH tends to shift to the acidic side. When the carbon becomes acidic as described above, when it is added to the aqueous resin, the stability may be reduced.

On the other hand, carbon having the above-mentioned oxygen content and pH which is preferably used in the present invention maintains neutral or alkaline even though it has a high oxygen content, and is stable. It can be added to an aqueous fluororesin. Although the detailed structure of carbon having such an oxygen content and pH is not clear, in the present invention, a functional group such as a carboxyl group, a hydroxyl group, or a ketone group is added to the carbon surface, and the hydrogen contained in these functional groups is included. A part of which is substituted with an alkali metal such as sodium is preferably used.

The coating layer 4 may be any coating film formed of the above-mentioned aqueous resin, and may contain a resin other than the above-mentioned aqueous resin, if necessary, without departing from the object of the present invention. Can also. Further, the coating layer 4 may be composed of a plurality of layers as necessary. Further, the coating layer 4 may be appropriately added with a film-forming aid, a pigment dispersant, a thickener, a leveling agent, a thixotropy-imparting agent, a structural viscosity-imparting agent, etc., without departing from the object of the present invention. An appropriate amount of the agent can be added as needed.

The coating layer 4 is the outermost layer of the charging member of the present invention, that is, the layer forming the surface of the charging member, and the surface roughness of the coating layer 4 is the surface roughness of the member. In the present invention, the surface roughness of the coating layer 4, that is, the surface roughness of the member is JIS based on the viewpoint of preventing image defects and the like.
The 10-point average roughness Rz is preferably 4 μm or less, more preferably 3 μm or less, and particularly preferably 2 μm or less. Such surface roughness can be easily achieved by forming the coating layer 4 using the above-mentioned aqueous resin.

The thickness of the coating layer 4 is not particularly limited, but is not more than 30 μm, especially 1 to 15 μm.
It is preferably set to μm. The thickness of the coating layer 4 is 30 μm
If it exceeds 3, the film may be too hard and the flexibility of the coating layer 4 may be impaired. The method of forming the coating film layer 4 is not particularly limited, but a method of preparing a coating material containing each of the above components constituting the coating film layer 4 and applying the coating material by a dipping method or a spray method is preferable. Used.

The charging member of the present invention has the coating layer 4 formed as the outermost layer outside the elastic layer 3 as described above, for example. The other coating layer can be formed as an intermediate layer between them. For example, when the elastic layer 3 is formed using a polyurethane foam, an acrylic resin is used to reduce noise when applying a voltage and to improve the surface smoothness of the elastic layer 3.
Polyester resin, polyurethane resin, nylon resin,
A coating film obtained by adding a conductive agent to a base resin such as an epoxy resin, a urethane-modified acrylic resin, a butyral resin, a phenol resin, a vinylidene chloride-based copolymer, and a polyvinyl acetal resin can be provided as an intermediate layer. The resin forming the coating film provided as the intermediate layer is not particularly limited, but in the present invention, it is preferable to use an aqueous resin.

As described above, the charging member of the present invention uses the water-based resin for the coating layer 4 to form a coating layer on the elastic layer 3 or the intermediate layer by dipping or spraying. In addition, a smooth member surface is obtained without swelling of the elastic layer 3 and the intermediate layer, thereby effectively preventing the adhesion of the residual toner, and forming the coating layer 4 from a mixture of a specific aqueous resin. By doing, the water resistance of the coating film is improved, and a coating film that is difficult to dissolve even under high temperature and high humidity is obtained.
Since the negative charging property is suppressed, it is possible to prevent image defects due to the charging memory even under low temperature and low humidity.

The charging member of the present invention is disposed in contact with a member to be charged such as a photosensitive drum, and charges the member by applying a voltage between the member and the member to be charged. However, 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 that charging is performed by applying a voltage on which a voltage is superimposed, so that the member to be charged can be charged more uniformly. Further, the contact pressure between the charging member of the present invention and the member to be charged is not particularly limited.
The amount is preferably from 0 to 2000 g, particularly preferably from 100 to 1000 g, whereby good charging can be reliably obtained.

As for the 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.

[0027]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Example 1 An elastic layer A having a thickness of 3 mm was formed on the outer periphery of a metal shaft, a coating layer A having a thickness of 300 μm was formed on the elastic layer A, and a thickness was further formed on the coating layer A. Each of the coating layers B having a thickness of 10 μm was formed by using a dipping method to prepare a charging roller. The configurations of the elastic layer A, the coating layer A, and the coating layer B are as follows. The surface roughness of the obtained charging roller was 0.7 μm in terms of JIS 10-point average roughness Rz, and the contact angle of the charging roller surface with water was 105 °. The contact angle was measured using the method described above.

[0028]Elastic layer A Polyester polyol, isocyanate and carbon
Urethane foam (density: 0.48 g)
/ Cm^Three).Coating layer A Water-based acrylic resin (glass transition temperature Tg: -48 ° C)
Formed by applying a paint with carbon added,
5 × 10 volume resistivity⁷It adjusted to Ω · cm. Coating layer B (Surface layer) Fluoroethylene-vinyl ether copolymer aqueous fluorine
Resin (glass transition temperature Tg: 35 ° C., 40% by weight), water
Urethane resin (glass transition temperature Tg: -40 ° C, 20
Wt%), a methyl methoxymethyl group and a methylol group.
Lamin resin (solid content ratio (fluorine resin + urethane resin) /
Melamine resin = 20/1) and polytetrafluoroe
Tylene fine particle dispersion (particle size: 0.15 μm, 4
0% by weight) and paint with carbon.
It is formed by fabric, and the volume resistivity is 5 × 10⁷Ω
cm. Note that carbon has an oxygen content of 10
% And a pH of 7.3 were used. "Melamine tree with methoxymethyl and methylol groups
Fluoroethylene-vinyl ether copolymer crosslinked with fat
Combined water-based fluororesin (glass transition temperature T of fluororesin
g: 35 ° C., 40% by weight) and an aqueous urethane resin (urea)
Glass transition temperature Tg of tan resin: -40 ° C, 20 weight
%), (Solid content ratio (fluororesin + urethane resin) / mela
Min resin = 20/1), and polytetrafluoroethylene
Ren fine particle dispersion (particle size: 0.15 μm, 40
% By weight) and paint with carbon added
And the volume resistivity is 5 × 10⁷Ω ・ c
m. In addition, carbon has an oxygen content of 10%,
The one having a pH of 7.3 was used. 』

The obtained charging roller was mounted on a printer, and an image was displayed in an environment of normal temperature and normal humidity (20 ° C./50% RH).
No image deterioration was observed even when zero images were taken out. Also, when the charging roller is attached to a printer and left in an environment of high temperature and high humidity (32 ° C./85% RH) for 3 days, and an image is displayed under the environment, a good image without any abnormality is obtained. Obtained. Furthermore, even if this charging roller is attached to a printer and left for 3 days in a low-temperature and low-humidity (15 ° C./10% RH) environment, an image is displayed in that environment.
A good image was obtained without any abnormality.

Comparative Example 1 A charging roller was prepared in the same manner as in Example 1 except that the coating layer A was replaced with the following coating layer C and the coating layer B was replaced with the following coating layer D. The surface roughness of the obtained charging roller is JIS
The ten-point average roughness Rz was 9.2 μm, and the contact angle of the charging roller surface with water was 115 °. Coating layer C The coating layer was formed by applying a coating material in which ketjen black carbon was added to a urethane resin dissolved in toluene, and the volume resistivity was adjusted to 5 × 10 ⁷ Ω · cm. Coating layer D The coating layer D was formed by applying a coating material in which Ketjen black carbon was added to a nylon resin dissolved in methanol, and the volume resistivity was adjusted to 5 × 10 ⁷ Ω · cm. The obtained charging roller is mounted on a printer, and the room temperature and the normal humidity (2
When an image was displayed in an environment of 0 ° C./50% RH), a dot-like defect was generated in the image from the beginning, and when the roller was observed, toner adhered to the concave portion of the roller surface.

Comparative Example 2 A charging roller similar to that of Example 1 was prepared except that the coating layer B was changed to the following coating layer E. The surface roughness of the obtained charging roller was 0.5 μm in JIS10 point average roughness Rz,
The contact angle of the charging roller with water was 80 °. Coating layer E Polytetrafluoroethylene fine particle dispersion (particle size: 0.15 μm, 60% by weight), aqueous vinylidene chloride resin (30% by weight), and aqueous butyral resin (10%)
% By weight) and applying a paint to which carbon has been added, and has a volume resistivity of 5 × 10 ⁷ Ω · c.
m. In addition, carbon has an oxygen content of 10%,
The one having a pH of 7.3 was used. When the obtained charging roller was mounted on a printer and an image was displayed under an environment of normal temperature and normal humidity (20 ° C./50% RH), a good image was obtained. No image deterioration was observed. However, after attaching this charging roller to a printer and leaving it in a high-temperature and high-humidity (32 ° C./85% RH) environment for 3 days, an image was taken out in that environment. When the roller was observed, the coating layer E was partially dissolved.

Comparative Example 3 A charging roller similar to that of Example 1 was prepared except that the coating layer B was changed to the following coating layer F. The surface roughness of the obtained charging roller was 0.5 μm in JIS10 point average roughness Rz,
The contact angle of the charging roller with water was 105 °. Coating layer F Fluoroethylene-vinyl ether copolymer water-based fluororesin (glass transition temperature Tg: 35 ° C, 40% by weight), water-based urethane resin (glass transition temperature Tg: -40 ° C, 20
% By weight) and a dispersion of polytetrafluoroethylene fine particles (particle size: 0.15 μm, 40% by weight), and formed by applying a coating material to which carbon is added, and has a volume resistivity of 5 × 10 ⁷ Ω.・ Adjusted to cm.
The carbon used had an oxygen content of 10% and a pH of 7.3. When the obtained charging roller was mounted on a printer and an image was formed at normal temperature and normal humidity (20 ° C./50% RH), a good image was obtained. No deterioration was observed. Also, after attaching this charging roller to a printer and leaving it in a high temperature and high humidity (32 ° C./85% RH) environment for 3 days,
Even when an image was displayed under the environment, a good image was obtained without any abnormality. However, when the charging roller is mounted on a printer, the charging roller is operated in a low-temperature and low-humidity environment (15 ° C./10% RH).
After being left for a few days, an image was taken out in that environment, and an image defect occurred due to the charged memory.

[0033]

The charging member of the present invention has excellent surface smoothness and, when used in an electrostatic latent image process in a copying machine, a facsimile, a printer, etc., causes image defects due to dissolution of a coating film in any environment. In addition, stable charging performance can be exhibited for a long time without causing image defects due to the charging memory. 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 without causing deterioration in charging performance due to long-term use.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view for explaining a contact angle in the present invention.

FIG. 3 is a cross-sectional view illustrating an example of the configuration 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

[Procedure amendment]

[Submission date] March 8, 2000 (200.3.8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

[0028]Elastic layer A Polyester polyol, isocyanate and carbon
Urethane foam (density: 0.48 g)
/ Cm^Three).Coating layer A Water-based acrylic resin (glass transition temperature Tg: -48 ° C)
Formed by applying a paint with carbon added,
5 × 10 volume resistivity⁷It adjusted to Ω · cm. Coating layer B (Surface layer) Melamine resin having methoxymethyl group and methylol group
-Crosslinked fluoroethylene-vinyl ether copolymer
Body water-based fluororesin (glass transition temperature Tg of fluororesin:
35 ° C, 40% by weight) and water-based urethane resin (urethane
Glass transition temperature Tg of resin: -40 ° C, 20% by weight),
(Solid content ratio (fluorine resin + urethane resin) / melamine tree
Fat = 20/1), and polytetrafluoroethylene fine
Particle dispersion (particle size: 0.15 μm, 40 weight
%) And apply a paint with carbon added
And a volume resistivity of 5 × 10⁷Ω · cm
It was adjusted. The carbon has an oxygen content of 10% and a pH of 10%.
7.3 was used.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C09D 127/18 C09D 127/18 175/04 175/04 F16C 13/00 F16C 13/00 A EF term ( Reference) 2H003 BB11 CC05 EE12 3J103 AA02 AA13 AA23 AA33 AA37 AA51 FA30 GA02 GA57 GA58 HA04 HA11 HA12 HA41 HA52 HA54 4F100 AA37B AK17B AK25 AK36B AK51A AK51B BA02 BA07 CC00B DA16 DD01 EH46B00 J05 J03Y03J03B CD121 CD122 CD131 CD132 DA162 DG002 HA026 KA03 MA02 MA08 MA10 MA14 NA02 NA17 PB09 PB11 PC08

Claims (9)

[Claims] 1. A charging member for charging an object to be charged by contacting the object to be charged and applying a voltage between the member and the object to be charged, wherein an elastic layer is provided directly on the outside of the elastic layer. Or a coating layer formed via another layer, and the coating layer is formed of a mixture of an aqueous fluororesin and an aqueous urethane resin cross-linked by a melamine resin and polytetrafluoroethylene fine particles. A charging member characterized by the above-mentioned. 2. The aqueous fluororesin has a glass transition temperature Tg.
Is a fluoroethylene-vinyl ether copolymer at 20 to 50 ° C., and the content of the resin in the coating layer is 20 to 50 ° C.
The charging member according to claim 1, wherein the amount is 60% by weight. 3. An aqueous urethane resin having a glass transition temperature T
3. The charging member according to claim 1, wherein g is -50 to 0 [deg.] C., and the content of the resin in the coating layer is 10 to 30% by weight. 4. The ratio of the water-based fluororesin and the water-based urethane resin to the melamine resin in the water-based fluorine-containing resin and the water-based urethane resin crosslinked by the melamine resin is such that the solid content weight ratio is 5/1 ≦ (fluororesin + urethane resin).
/ Melamine resin ≦ 200/1 ”, the charging member according to any one of claims 1 to 3. 5. The polytetrafluoroethylene fine particles,
The charging member according to any one of claims 1 to 4, wherein the particle diameter is 5 µm or less, and the content of the fine particles in the coating layer is 20 to 60% by weight. 6. The charging member according to claim 1, wherein the coating layer contains carbon having an oxygen content of 5% or more and a pH of 5 or more. 7. The charging member according to claim 1, wherein the elastic layer is a urethane foam having a density of 0.05 to 0.9 g / cm ³ . 8. The surface according to claim 1, wherein the surface is 4 μm or less on a JIS 10-point average roughness Rz scale.
The charging member according to any one of the above. 9. 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.