JP2003140443A - Charging member and charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging member which can eliminate the problems of initial fogging, durable fogging, tight adhesion of OPC and nip traces, ensures the good electrostatic charging operation under severe conditions and makes good images stably obtainable. SOLUTION: The charging member is a charging member to be abutted to a charged member and to charge the charged member by applying a voltage between itself and the charged member and is furnished with an elastic layer and at least one resin layer formed on this elastic layer, in which the outermost resin layer abutted to the charged member is formed of a resin material containing >=50 wt.% polyamide resin and <=50 wt.% fluororesin component and/or fluorine compound component and when a corona discharge is generated to charge the outermost resin layer by applying the voltage of 8 kV to a corona discharger arranged apart a spacing of 1 mm from the surface of the outermost resin layer in a state where the outermost resin layer does not contain conducting agents at all, the maximum value of the surface potential after 0.3 seconds is <=50 V and the surface potential after 10 seconds is <=5 V.

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 which are preferably used when a charged body such as a photoconductor is charged 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 photoconductor is uniformly charged, and an image is projected from the optical system on the photoconductor so that a portion exposed to light is exposed. An electrostatic latent image is formed by removing the electrostatic charge to form an electrostatic latent image, and then a toner image is formed by adhesion of toner, and the toner image is transferred to a recording medium such as paper, and then printed. The method is taken.

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

For this reason, efforts have been made to a charging system capable of charging with a lower applied voltage than that of corona discharge and suppressing the generation of harmful substances such as ozone, and the corona charging system. As an alternative charging method, a contact method has been proposed in which a charging member to which a voltage is applied is brought into contact with an object to be charged such as a photoconductor at a predetermined pressure to charge the object to be charged.

In this case, as the charging member used in this contact charging system, for example, an acrylic layer is used on the surface of an elastic layer such as rubber or urethane foam to secure surface smoothness, adjust resistance, and improve charging characteristics. It is known that a resin layer is formed by applying a resin solution such as urethane, nylon, polyethylene, epoxy, polyester, polyether, polystyrene, phenol, ABS, polyamide, urethane modified acrylic resin by a dipping method or a spray method. .

[0006]

However, the above-mentioned conventional charging member used in this contact charging system has the following problems.

[Initial Fogging / Durability Fogging] The charging member is the cause of recent demands for high image quality, low cost (low voltage, downsizing of members, etc.), high speed, and high durability in the electrophotographic field. Problems such as initial image defects (initial fog) and durable image defects (durability fog) that occur when the number of prints are piled up have become apparent due to charging defects that occur next. However, the root cause of this has not been clarified, and there are currently no clear measures that can be fully satisfied.

[OPC close contact] In the contact charging system, the charging member is kept in contact with the photosensitive member (OPC) for a long time, so that the contact between the photosensitive member and the surface of the charging member occurs (adhesion), and the coating film. Peeling or photoconductor contamination may occur. In particular, due to the recent requirement for multi-environment, there is a strong demand for the development of a charging member, particularly a resin layer on the surface of the member, which is excellent in releasability without adhering (adhesion) to the photoreceptor even under severe conditions such as temperature / humidity. There is.

The present invention has been made in view of the above circumstances, and can solve the problems of [initial fog / durability fog] and [OPC adhesion], and ensures a good charging operation even under severe conditions. It is an object of the present invention to provide a charging member that can be used for various purposes and can stably obtain a good image, and a charging device using the charging member.

[0010]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above-mentioned object, the present inventor has formed at least one resin layer on an elastic layer to form a photoreceptor or the like. In the case of obtaining a charging member that abuts on the body to be charged and charges the same, the outermost resin layer contacting the body to be charged is 50
The outermost resin layer is formed of a resin material containing not less than 50% by weight of a polyamide resin and not more than 50% by weight of a fluorine resin component and / or a fluorine compound component, and the outermost resin layer contains no conductive agent. Surface of resin layer and 1mm
When a voltage of 8 kV is applied to the corona discharger arranged at intervals of 4 to generate corona discharge to charge the outermost resin layer surface, the maximum value of the surface potential after 0.3 seconds is 50 V or less. And the surface potential after 5 seconds is 5V
By doing the following, it is possible to solve the problems of the above [initial fog / durability fog], [OPC adhesion] and [nip mark] as described below, and it is possible to perform even under severe conditions. It has been found that a charging member can be obtained which can reliably perform the charging operation and can stably obtain a good image.

[Initial fog / durability fog] According to the study by the present inventor, the above-mentioned [initial fog / durability fog] is
Mainly depends on the resin layer of the charging member, particularly the outermost resin layer. Among them, as for “initial fog”, when the outermost resin layer of the charging member contains no conductive agent, the surface of the outermost resin layer is When a voltage of 8 kV was applied to a corona discharger arranged at an interval of 1 mm to generate a corona discharge and the outermost resin layer surface was charged, the maximum value of the surface potential after 0.3 seconds was 50 V. When the charging member is capable of retaining the “surface charging potential characteristic” which is the following and the surface potential after 10 seconds is 5 V or less, the occurrence of the “initial fog” can be extremely effectively prevented, and As for "durability fog", it has been found that if "initial fog" does not occur, it is much more advantageous than "initial fog" even if there is some deterioration. On the other hand, in order to suppress "durability fog", it has been found that, in addition to the "surface charging potential characteristic", the toner adhesion and frictional properties of the outermost resin layer of the charging member are important. That is, if the charging member has a large amount of toner adhesion or has a property of making it difficult to remove the toner, fogging due to toner damage to the charging member such as toner filming and toner fusion will occur. And when the frictional property of the outermost resin layer is high,
Excessive shear stress between the photoconductor and the charging member,
Fogging occurs due to damage such as slack, wrinkles, and holes. Therefore, as a result of further study on this point,
When the charging member has a friction characteristic such that the friction coefficient of the charging member is 0.5 or less when it is pressed against a cloth of 100% cellulose, 30 g / m ² , 70 mesh under a load of 100 gf, this "durable fog" is obtained. It has been found that the occurrence of "" can be suppressed very effectively.

Here, the reason for evaluating the surface potential characteristics when corona discharge is used as a measure against "fogging" is as follows. That is, in the charging roller, the voltage is normally applied by applying a voltage to the shaft,
When a voltage is applied to the shaft, the charge immediately moves to the surface of the charging roller, and it is necessary to charge the photoconductor. If this ability is insufficient, the photoreceptor is not sufficiently charged, and image defects, especially "fog" occur. This is partly due to the electrostatic capacity and resistance of the roller, but these values cannot be sufficiently correlated with the charging ability. However, the charging ability can be evaluated almost directly by using the method of measuring the response of the charging roller to the surface charge, that is, the surface potential due to the corona discharge.

Further, when the charging potential characteristic is evaluated, the evaluation is carried out in the state where the outermost resin layer contains no conductive agent at all. That is, it has been found out by the inventors of the present invention that the image characteristics, in particular, "fogging" greatly depend on the charging characteristics of the charging roller, and in particular, they largely depend on the outermost resin layer of the roller.
Then, it is appropriate to evaluate the performance of the resin alone when this outermost resin layer is formed on the roller surface,
It is not preferable to include other elements such as a conductive agent.

Further, the reason for evaluating the charging potential 10 seconds after the charging by the corona discharge is as follows. That is, a large potential of 8 kV (which is considered to be a slightly lower voltage in the charging roller) is applied to the surface of the charging roller by corona discharge, but normally such a large voltage is not applied in an actual machine. But,
Due to problems such as measurement accuracy, reproducibility, and measurement method, such a large voltage is applied. Therefore, considering this point,
This is because the surface potential is evaluated when an interval of 10 seconds is given to allow the charges to escape, and this evaluation method is appropriate based on empirical rules.

[OPC Adhesion] The problem of [OPC adhesion] can be solved by good releasability as described above. According to the study of the present inventors, the charging member is made of cellulose. The releasability of the surface of the member is 100%, if the member has friction characteristics such that the coefficient of friction with respect to the cloth of 30 g / m ² , 70 mesh is 100 when the load of 100 gf is applied under pressure. It has been found that the above can be sufficiently secured, and the problem of [OPC adhesion] can be sufficiently solved.

By forming the outermost resin layer of the charging member with a resin material containing 50% by weight or more of polyamide resin and 50% by weight or less of fluorine resin and / or fluorine compound, [initial fog / durability] It is possible to obtain the outermost resin layer having the above-mentioned "surface charging potential characteristic" which can solve the problem of "fog", and also the outermost resin layer which has the above-mentioned "friction characteristic" which can solve the problem of "OPC adhesion". To obtain a charging member that can be easily obtained, can solve these problems, can reliably perform a good charging operation even under severe conditions, and can stably obtain a good image. That is, the present invention has been completed.

Therefore, according to the present invention, the member to be charged is brought into contact with
A charging member for charging the charged body by applying a voltage to the charged body comprises an elastic layer and at least one resin layer formed on the elastic layer. The outermost resin layer contacting the member to be charged is a charging member formed of a resin material containing 50% by weight or more of a polyamide resin and 50% by weight or less of a fluororesin component and / or a fluorine compound component, In addition, in a state where the outermost resin layer does not contain any conductive agent, a voltage of 8 kV is applied to a corona discharger arranged at a distance of 1 mm from the surface of the outermost resin layer to generate corona discharge, and the corona discharge is generated. Provided is a charging member, which has a maximum surface potential of 50 V or less after 0.3 seconds and a surface potential of 5 V or less after 10 seconds when the outer resin layer surface is charged. .

Further, the present invention comprises a charging member which is in contact with the charged body and charges the charged body, and a voltage applying means for applying a voltage between the charged body and the charging member. In a charging device, there is provided a charging device characterized by using the above-mentioned charging member of the present invention.

The present invention will be described in more detail below.
As described above, in the charging member of the present invention, the outermost resin layer in contact with the body to be charged is made up of 50% by weight or more of polyamide resin and 5% by weight.
The conductive member is formed of a resin material containing 0% by weight or less of a fluororesin component and / or a fluorine compound component.

The polyamide resin used as the resin material for forming the outermost resin layer may be any one as long as it can form a film on the elastic layer serving as the base of the charging member. Aliphatic, aromatic-aromatic, aliphatic-
It may have any aromatic constitution, as long as it can obtain the above-mentioned charging potential characteristics by corona discharge.

Although this polyamide resin has good electric characteristics and physical properties preferable as a skin layer of a charging member,
It also has the disadvantage of high tack and high friction.
Therefore, in the present invention, by adding and using a fluororesin component and / or a fluorine compound component together, the above problems of tackiness and frictional properties are solved while maintaining good electrical characteristics.

Examples of the above-mentioned fluororesin component include polytetrafluoroethylene, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene- Ethylene copolymer, polychlorotrifluoroethylene, chlorotrifluoroethylene-ethylene copolymer, tetrafluoroethylene-vinylidene fluoride copolymer, polyvinylidene fluoride, polyvinylidene fluoride copolymer, vinylidene fluoride-hexa Examples include fluoropropylene copolymers, and one or more of these can be used.

The fluororesin component and the polyamide resin may be simply blended, or may be chemically bound by a graft, a bond through a crosslinking agent such as isocyanate, or the like.

Further, as the fluorine compound component, perfluorooctylethyl methacrylate, 2,2,3,4,
4,4-hexafluorobutyl methacrylate, 2,2,3,
Examples thereof include 3-tetrafluoropropyl methacrylate, trifluoroethyl methacrylate, a fluorine-modified acrylate having a fluoroalkyl group bonded to the end of a polyol, and a fluorine-modified polyamide having a fluoroalkyl group bonded to the end of a polyamide. One or two of these may be mentioned. More than one species can be used.

Here, although not particularly limited,
The fluoroalkyl group C _n F _{2n + 1} in the fluorine compound preferably has n of 6 or more. This is because when n is 5 or less, the low surface energy peculiar to the fluoroalkyl group may not be sufficiently exhibited, and when n is 6 or more, the characteristics are rapidly exhibited, and low friction property and low adhesiveness are good. This is because it is often exhibited in.

The fluorine compound component and the polyamide resin may be simply blended, but it is particularly preferable that they are chemically bonded by a bond such as a graft or a crosslinking agent such as isocyanate. This is because when the fluorine compound has a low molecular weight, there is a possibility that contamination of the photoreceptor and a decrease in durability may occur due to bleed-out. Further, the outermost resin layer preferably has an inclined structure in which fluorine is dense on the outside and polyamide resin is dense on the inside from the viewpoint of action and effect, but the fluorine compound has low polarity, Even if it is combined with polyamide resin, it is easier on the air side, that is, the outermost side,
Even if it is bonded to a polyamide resin, there is no particular disadvantage in obtaining the above-mentioned tilted structure.

In the present invention, the fluororesin component and the fluorocompound component may be used in combination.

The outermost resin layer constituting the member surface of the charging member of the present invention contains the above-mentioned polyamide resin and the above-mentioned fluororesin component and / or fluorocompound component as the resin component, as described above. In this case, the polyamide resin content is 50% by weight or more, more specifically 50 to 99.9% by weight, preferably 60 to 99% by weight, and the fluororesin component and / or the fluorine compound component is 50% by weight or less, more specifically. 0.1 to 50% by weight, preferably 1 to 40
It is defined as weight%. Here, if the polyamide resin component is less than 50% by weight, good electrical properties and mechanical properties peculiar to the polyamide resin may not be obtained, and if the amount of the fluororesin component and / or the fluorine compound component is too small, the tackiness against tack may be reduced. The potency is not so great, and when it is too large, the potency does not change so much, which may cause problems such as phase separation and deterioration of electrical properties.

Although not particularly limited, silica powder may be added and compounded in the resin material forming the outermost resin layer, which reduces the contact area, thereby improving the adhesion (non-adhesiveness). ) May be improved. Further, in this resin material, a conductive agent can be added as necessary to adjust the resistance to a desired value. In this case, the conductive agent is not particularly limited, and various electronic conductive agents and various ionic conductive agents can be used. Although an agent can be used, a conductive powder such as carbon is particularly preferably used in the present invention. The electric resistance of the outermost resin layer is not particularly limited, but is usually 1 × 10 ⁸ to 1 × 10 ¹⁵ Ω · cm, and particularly 1
It is preferably × 10 ¹⁰ to 1 × 10 ¹³ Ω · cm.

The method of forming the outermost resin layer on the charging member is not particularly limited, but a coating material containing each of the above components is prepared and the coating material is applied to the charging member by a dipping method, a spray method or the like. The method is preferably used.

The thickness of the outermost resin layer is appropriately set according to the form of the charging member and is not particularly limited, but is usually 30 μm or less, and particularly preferably 5 to 20 μm. If it exceeds 30 μm, the outermost resin layer may be hardened and the flexibility of the outermost resin layer may be impaired.

If necessary, additives such as a cross-linking agent, a thickener, a thixotropy-imparting agent, and a structural viscosity-imparting agent can be added to the resin composition forming the outermost resin layer.

The charging member of the present invention is such that at least the surface of the member that comes into contact with the member to be charged such as the photosensitive drum is formed of the outermost resin layer, and its form is roll, plate, block or sphere. It may be in any suitable form such as a brush, and is not particularly limited, but it is usually preferable to use a roll-shaped charging roller having the surface layer on the surface of the member, for example, as shown in FIG. 2), an elastic layer 2 is formed on the outer periphery of the shaft 1, and the outermost resin layer 3 is formed on the elastic layer 2 as an example.

In this case, a metal or plastic shaft can be used as the shaft 1.
The shaft 1 may be omitted depending on the form of the member and the mechanism of the charging device in which the charging member is used.

The elastic body forming the elastic layer 2 is not particularly limited as long as it is an elastic body capable of obtaining a good contact state with the member to be charged, and a known rubber or resin,
Alternatively, it can be formed of these foams (hereinafter referred to as “foam”). Specifically, rubber having a base rubber such as polyurethane, silicone rubber, butadiene rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, and epichlorohydrin rubber. The composition is exemplified, but polyurethane is particularly preferable, and the expansion ratio is more preferably 1.5 to 5
Double polyurethane foam is used. The foam density in this case is preferably about 0.05 to 0.9 g / cm ³ .

A conductive agent should be added to the elastic layer 2.
To give or adjust conductivity to obtain a predetermined resistance value.
be able to. The conductive agent is not particularly limited,
Lauryl trimethyl ammonium, stearyl methyl
Ammonium, octadodecyltrimethylammonium,
Hexadecyl trimethyl ammonium, modified fatty acid di
Methyl ethyl ammonium perchlorate, chlorate,
C. Hydrofluoride, sulfate, ethosulfate, bromide
Halogenated benzyl salt such as benzyl salt and benzyl chloride salt
Surface-active substances such as quaternary ammonium salts such as
Agent, aliphatic sulfonate, higher alcohol sulfate
Salt, higher alcohol ethylene oxide addition sulfuric acid ester
Salt, higher alcohol phosphate ester salt, higher alcohol
Anion such as ethylene oxide addition phosphate ester salt
Surfactant, higher alcohol ethylene oxide, poly
Ethylene glycol fatty acid ester, polyhydric alcohol fat
Antistatic properties such as nonionic antistatic agents such as fatty acid esters
Agent, NaClO_Four, LiAsF₆, LiBF_Four, NaSC
Li such as N, KSCN, NaCl⁺, Na⁺, K⁺Circumference
Periodic Table Group 1 metal salt or NH_Four ⁺Electrolysis of salt
Quality, ketjen black, acetylene black, etc.
Conductive carbon, SAF, ISAF, HAF, FE
Carbon for rubber such as F, GPF, SRF, FT, MT,
Oxidized carbon for color (ink), thermal decomposition
Carbon, natural graphite, artificial graphite, Anne
Timon-doped tin oxide, titanium oxide, zinc oxide, nickel
Metals such as aluminum, copper, silver and germanium, and metal oxides, and
Conductivity of lianiline, polypyrrole, polyacetylene, etc.
Examples thereof include polymers. In this case, the distribution of these conductive agents
The total amount is appropriately selected according to the type of composition, and is usually
Volume resistivity of the conductive layer is 1 × 10 ²~ 1 x 10^TenΩ · cm,
Preferably 1 × 10³~ 1 x 10⁷Ω · cm
Adjusted.

Here, when the outermost resin layer 3 is formed by coating the elastic layer 2 with the coating material of the resin material as described above, the solvent used for the coating material may be water-based or solvent-based. Is a solvent type, as shown in FIG. 1 (B),
From the viewpoint of ensuring smoothness, durability, charging uniformity, manufacturing stability, etc., it is preferable to provide an intermediate resin layer 4 formed of an aqueous resin between the elastic layer 2 and the outermost resin layer 3.

In this case, the water-based resin forming the intermediate resin layer 4 may be of any type as long as the solvent is water, and includes water-soluble type, emulsion type, suspension type, etc., particularly carboxyl group and hydroxyl group. ,
A resin having active hydrogen such as an amino group is preferably used. More specific examples include polyester-based, acrylic-based, urethane-based, and hot water-soluble systems such as polydioxolane. Among these, acrylic resin has a much smaller dielectric constant than urethane, nylon, etc., which have been widely used as a resin for charging members, so that the electrostatic capacity also becomes smaller, and the electrical conductivity between the charging member and the photoconductor due to the application of alternating current is reduced. It is particularly preferably used because the attractive force and repulsive force are reduced and the generation of charging noise is suppressed. Among the acrylic resins, a soap-free emulsion type one having a glass transition temperature of −50 to 10 ° C., a content ratio of a carboxyl group and a hydroxyl group of 2 to 5% by weight, has a good crosslinking effect and a low hardness. It is preferably used because it is possible.

A conductive agent may be added to the intermediate resin layer 4 to impart or adjust conductivity. In this case, as the conductive agent, the same conductive agents as those exemplified for the elastic layer 2 can be exemplified, but it is preferable to use carbon among them, and particularly, the oxygen content is 5% or more,
In particular, 7% or more, more preferably 9% or more,
Further, the pH is preferably 5 or more, particularly 6 or more, and further preferably 7 or more. That is, the oxygen content of ordinary carbon is about 0.1 to 3%, and there is some carbon that has been subjected to an oxidation treatment, but the oxygen content of this oxidation-treated carbon slightly increases. As a result, the pH tends to shift to the acidic side, and if the carbon is acidic, the stability may decrease when added to the water-based resin. On the other hand, the above-mentioned carbon maintains neutrality or alkalinity despite having a large oxygen content, and can be stably added to the water-based resin. Further, those obtained by adding a functional group such as a carboxyl group, a hydroxyl group or a ketone group to the surface of carbon and substituting a part of hydrogen contained in these groups with an alkali metal such as sodium are preferably used. In addition, this specific oxygen content and pH
When the outermost resin layer 3 is formed of a water-based paint, the carbon having a value is also suitably used as the carbon to be added to the outermost resin layer 3 as a conductive agent.

The resistance of the intermediate resin layer 4 has a volume resistivity of 1
It is preferably from 0 ³ to 10 ¹² Ωcm, particularly from 10 ⁵ to 10 ¹⁰ Ωcm, and the weight of carbon added is usually 0.01 to 40.
It is set to the weight%, especially about 5 to 20 weight%.

The intermediate resin layer 4 contains appropriate additives such as a film-forming aid, a pigment dispersant, a thickener, a leveling agent, a thixotropy-imparting agent, and a structural viscosity-imparting agent within the range not departing from its purpose. Can be added in an appropriate amount if necessary.

The intermediate resin layer 4 is preferably formed by using a water-based resin as described above, but a resin other than this water-based resin may be contained, and if necessary, this intermediate resin layer 4 It is also possible to form a plurality of intermediate resin layers 4. Further, the thickness of the intermediate resin layer 4 is not particularly limited, but is usually 5 to 500 μm, and particularly 50.
The thickness is preferably about 400 to 400 μm, and if it is less than 50 μm, sufficient smoothness and noise resistance may not be obtained, while if it exceeds 400 μm, the thickness of the elastic layer 2 becomes relatively thin and the roller The hardness may increase or the cost may increase.

The method of forming the intermediate resin layer 4 is not particularly limited, and a known dipping method, spraying method, extrusion molding method or the like can be adopted. Usually, a coating material in which each component is dissolved or dispersed in a solvent is used. Is preferably used to form a coating film by a dipping method.

As described above, the charging member of the present invention has the outermost resin layer 3 formed on the elastic layer 2 via the intermediate resin layer 4 or directly. In this case, in any layer structure, the resistance suitable as the charging member is preferably 10 ² to 10 ¹² Ωcm in volume resistance, particularly 10 ⁵ to 10 ¹⁰ Ωcm in order to obtain a good image. Preferably there is. Also, if the surface of the charging member has irregularities,
It is preferable that the surface is as smooth as possible, because the toner may become clogged and cause defective images.
Ten-point average roughness Rz is 4 μm or less, further 3 μm or less,
It is particularly preferably 2 μm or less.

Here, in the charging member of the present invention, the above outermost resin layer does not contain any conductive agent (when the outermost resin layer contains a conductive agent, the conductive agent is excluded). Except that the charging member is formed in the same manner), a voltage of 8 kV is applied to a corona discharger arranged at a distance of 1 mm from the surface of the outermost resin layer to generate corona discharge, and the surface of the outermost resin layer is discharged. When charged, the maximum value of the surface potential after 0.3 seconds is 50 V or less, especially 35 V or less, and the surface potential after 10 seconds is 5 V or less, especially 3.5 V.
It has the following charging potential characteristics. As a result, it is possible to more reliably prevent the occurrence of the above-mentioned "fog", particularly the "initial fog". Further, according to the charging member of the present invention having the outermost resin layer formed, such charging potential characteristics can be easily achieved.

A specific method for measuring the surface potential of the charging member and evaluating the above-mentioned charging potential characteristics is, for example, using "Charge Roller Test System CRT2000" manufactured by QEA (Quality Engineering Associates, Inc.) in the United States. , As shown in FIG. That is,
The charging member (charging roller in the figure) on which the outermost resin layer is formed is used as a sample roller 21, and both ends of a shaft 22 of the sample roller 21 are fixed to a chuck 23, and a small scorotron discharger 24 and a surface electrometer are provided. 25 and the measuring unit 20 provided side by side with a predetermined distance from each other.
It is arranged facing the surface of No. 1 with a space of 1 mm,
The measurement unit 20 is moved from one end to the other end of the subject roller 21 at a constant speed while the subject roller 21 is kept stationary, and the surface potential of the subject roller 21 is measured while applying a surface charge to the subject roller 21. At this time, the moving speed of the measuring unit 20 may be adjusted to measure the “surface potential after 0.3 seconds” and the “surface potential after 10 seconds”. In this case, since the surface potential depends on temperature and humidity, the measurement is carried out in an atmosphere of normal temperature and normal humidity (22 ° C./50% RH) as standard conditions. The corona charge applied from the scorotron discharger 24 to the subject roller 21 is a negative charge, and the applied voltage is 8 kV as described above.

The charging member of the present invention preferably has a low frictional resistance on the surface thereof, and although not particularly limited, a load of 100 gf is applied to a cloth of 100% cellulose, 30 g / m ² , 70 mesh. It is preferable that the friction coefficient with respect to the cloth when pressed against the surface is 0.5 or less, particularly 0.3 or less. As a result, it is possible to more reliably prevent the occurrence of "fog", particularly the occurrence of "durable fog" and the "OPC adhesion". Further, according to the charging member of the present invention in which the outermost resin layer is formed, such surface friction characteristics can be easily achieved.

In this case, the friction coefficient can be measured by the measuring device shown in FIG. That is, the cellulose 10 is attached to the movable stage 52 provided on the base 51.
A 0%, 30 g / m ² , 70 mesh cloth (Bencott lint-free) 9 was fixed, and the charging member 8 of the present invention to be evaluated was placed in contact with this cloth. A load is applied to bring the cloth 9 and the charging member 8 into pressure contact with each other, and in this state, the movable stage 52 is moved back and forth to cause a friction speed of 100 mm / min.
The cloth 9 and the charging member 8 are frictionally moved with each other, the frictional resistance at this time is measured by the load cell 54, and the frictional coefficient of the charging member 8 with respect to the cloth (Bencott lint-free) 9 is obtained from the frictional resistance value. . The reason why the cloth of 100% cellulose, 30 g / m ² , 70 mesh (bencott lint-free) was selected as the friction partner material was that it was most correlated with the surface property of the charging member and the obtained friction coefficient. This is because the measurement range was appropriate.

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 remove the member to be charged. In this case, the voltage applied between the charging member and the body to be charged may be a DC voltage or an AC voltage, and is not particularly limited. It is preferable to apply a voltage obtained by superimposing an AC voltage on the charging target so as to perform charging, so that the member to be charged can be charged more uniformly.

Regarding the charging device using the charging member of the present invention, for example, as shown in FIG. 2, the charging member 5 of the present invention is used.
Contact the charged body 6 such as the photosensitive drum with a predetermined pressure,
A charging device configured to apply a voltage between the voltage applying unit 6 and the charging target 5 can be exemplified, but the charging device is not limited to this, and the charging target 6 and the charging member 5 are not limited thereto.
The mode, the voltage applying method by the voltage applying means 7 and the like may be changed appropriately.

[0051]

EFFECT OF THE INVENTION The charging member of the present invention can solve the problems of [initial fog / durability fog] and [OPC adhesion], and can reliably perform good charging operation even under severe conditions. Therefore, a good image can be stably obtained. Therefore, according to the charging device using the charging member of the present invention, a good charging operation can be stably performed over a long period of time.

[0052]

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

Example 1 A 100 μm thick layer was formed on the surface of an elastic layer (1.0 × 10 ⁶ Ω · cm) made of conductive urethane foam having a thickness of 3 mm formed on the outer periphery of a metal shaft.
m of the following intermediate resin layer A is formed, and a thickness of 10
The following outermost resin layer B having a thickness of μm was formed to prepare a charging roller having the same layer configuration as that shown in FIG.

Intermediate resin layer A Aqueous acrylic resin with carbon added is applied by a dipping method to form a volume resistivity of 5 × 10 ⁷ Ω.
・ Adjusted to cm. Outermost resin layer B Polyamide resin "H1060" (Sanyo Kasei) was dissolved in an ethanol solvent, and "Modiper F220" (Nippon Yushi Co., Ltd.) composed of a fluorine-acrylic block copolymer was added to 15 parts by weight of polyamide resin. After adding 1 part by weight, a coating material containing 10 parts by weight of a melamine cross-linking agent was further applied by a dipping method to form.

The resistance of the obtained roller is 8 × 10 ⁶ [Ω].
Met. When a voltage of 8 kV was applied to a corona discharger arranged with a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, 0.3
The maximum value of the surface potential after 3 seconds is 3 V, and 10
The surface potential after seconds was 0.13V. Furthermore, using the measuring device shown in FIG.
100% cellulose under the condition of 0% RH, 30 g / m ² ,
When a friction test was performed using a 70-mesh cloth, the friction coefficient was 0.28.

When the charging roller was mounted in a printer cartridge and left for 2 weeks at a temperature of 40 ° C. and a humidity of 95% RH, no close contact with the photoreceptor (OPC) was observed. Next, using the above cartridge after being left for two weeks, AC voltage Vpp = 1800V and DC voltage Vdc = −650.
When a picture was drawn with V, a good image was obtained. Further, when a picture was drawn at a DC voltage Vdc = -1260V, no initial image fog was seen. At this time, when the charging roller was taken out and the toner was wiped off, no toner remained on the roller. Further, even when the continuous 8000 images were output, the images were not deteriorated.

Example 2 The same intermediate resin layer A having a thickness of 100 μm was formed on the surface of an elastic layer as in Example 1, and further the outermost resin layer C having a thickness of 10 μm was formed thereon. ,
A charging roller having a layer structure similar to that of FIG. Resin layer C Polyamide resin "L203" (Sanyo Chemical Co., Ltd.) is dissolved in an ethanol solvent, and "Modiper F220" (Nippon Yushi-Seiyaku Co., Ltd.) composed of a fluorine-acrylic block copolymer is added to 10 parts by weight of the polyamide resin. After the addition, a coating material containing 10 parts by weight of a melamine crosslinking agent was applied by a dipping method to form a coating.

The resistance of the obtained roller is 6 × 10 ⁶ [Ω].
Met. When a voltage of 8 kV was applied to a corona discharger arranged with a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, 0.3
The maximum value of the surface potential after 7 seconds is 7 V, and 10
The surface potential after 0.2 seconds was 0.21V. Furthermore, using the measuring device shown in FIG.
100% cellulose under the condition of 0% RH, 30 g / m ² ,
When a friction test was conducted using a 70-mesh cloth, the friction coefficient was 0.32.

When the charging roller was mounted on a printer cartridge and left for 2 weeks at a temperature of 40 ° C. and a humidity of 95% RH, no close contact with the photoreceptor (OPC) was observed. Next, using the above cartridge after being left for two weeks, AC voltage Vpp = 1800V and DC voltage Vdc = −650.
When a picture was drawn with V, a good image was obtained. Further, when a picture was drawn at a DC voltage Vdc = -1260V, no initial image fog was seen. At this time, when the charging roller was taken out and the toner was wiped off, no toner remained on the roller. Further, even when the continuous 8000 images were output, the images were not deteriorated.

Example 3 The same intermediate resin layer A having a thickness of 100 μm was formed on the surface of the elastic layer as in Example 1, and further the outermost resin layer D having a thickness of 10 μm was formed thereon. As a result, a charging roller having a layer structure similar to that shown in FIG.

Outermost resin layer D Polyamide resin "A90" (Toray) was dissolved in ethanol solvent, and perfluoroalkyl group-containing emulsion "FC-5120" (manufactured by 3M Co.) was added to polyamide resin 1
After adding 3 parts by weight to 00 parts by weight, a coating material containing 5 parts by weight of an epoxy cross-linking agent was applied by a dipping method.

The resistance of the obtained roller is 1 × 10 ⁷ [Ω].
Met. When a voltage of 8 kV was applied to a corona discharger arranged with a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, 0.3
The maximum value of surface potential after 5 seconds is 5 V, and 10
The surface potential after 2 seconds was 0.43V. Furthermore, using the measuring device shown in FIG.
100% cellulose under the condition of 0% RH, 30 g / m ² ,
When a friction test was performed using a 70-mesh cloth, the friction coefficient was 0.36.

When the charging roller was mounted in a printer cartridge and left for 2 weeks at a temperature of 40 ° C. and a humidity of 95% RH, no close contact with the photoreceptor (OPC) was observed. Next, using the above cartridge after being left for two weeks, AC voltage Vpp = 1800V and DC voltage Vdc = −650.
When a picture was drawn with V, a good image was obtained. Further, when a picture was drawn at a DC voltage Vdc = -1260V, no initial image fog was seen. At this time, when the charging roller was taken out and the toner was wiped off, no toner remained on the roller. Further, even when the continuous 8000 images were output, the images were not deteriorated.

Example 4 The same intermediate resin layer A having a thickness of 100 μm was formed on the surface of the elastic layer as in Example 1, and the outermost resin layer E having a thickness of 10 μm described below was further formed thereon. As a result, a charging roller having a layer structure similar to that shown in FIG.

Outermost resin layer E Polyamide resin "Harmide 3228" (Harima Kasei)
Is dissolved in a toluene solvent, and the fluororesin “LF20
0 "(Asahi Glass Co., Ltd.) was added to 50 parts by weight of 100 parts by weight of the polyamide resin, and then a coating material containing 20 parts by weight of carbon and 5 parts by weight of an isocyanate crosslinking agent was applied by a dipping method.

The resistance of the obtained roller is 1 × 10 ⁶ [Ω].
Met. A charging roller was prepared in the same manner except that the conductive agent carbon was not added to the outermost resin layer E, and a voltage of 8 kV was applied to a corona discharger arranged at a distance of 1 mm from the roller surface. When the voltage was applied to generate corona discharge to charge the surface, the maximum value of the surface potential after 0.3 seconds was 31V, and the surface potential after 10 seconds was 2.76V. Further, using the measuring device shown in FIG. 3, this roller was subjected to a friction test using a cloth of 100% cellulose, 30 g / m ² , 70 mesh under the condition of temperature 22 ° C./humidity 50% RH. The coefficient is 0.
It was 33.

When the charging roller was mounted on a printer cartridge and left standing for 2 weeks at a temperature of 40 ° C. and a humidity of 95% RH, no close contact with the photoreceptor (OPC) was observed. Next, after being left for two weeks, using the above-mentioned power cartridge, an AC voltage Vpp = 1800V and a DC voltage Vdc = −650.
When a picture was drawn with V, a good image was obtained. Further, when a picture was drawn at a DC voltage Vdc = -1260V, no initial image fog was seen. At this time, when the charging roller was taken out and the toner was wiped off, no toner remained on the roller. Further, even when the continuous 8000 images were output, the images were not deteriorated.

Comparative Example 1 The same intermediate resin layer A having a thickness of 100 μm was formed on the surface of an elastic layer as in Example 1, and further the outermost resin layer F having a thickness of 10 μm was formed thereon. As a result, a charging roller having a layer structure similar to that shown in FIG.

Outermost resin layer F Fluorine resin "LF710N" (Asahi Glass Co., Ltd.) was dissolved in a methyl ethyl ketone (MEK) solvent, and 35 parts by weight of carbon was added to 100 parts by weight of the fluorine resin, and an isocyanate crosslinking agent was further added. 5 parts by weight of the coating material was applied by the dipping method to form.

The resistance of the obtained roller is 2 × 10 ⁶ [Ω].
Met. Further, a charging roller was prepared in the same manner except that carbon as a conductive agent was not mixed with the outermost resin layer F, and a voltage of 8 kV was applied to a corona discharger arranged with a distance of 1 mm from the roller surface. When a voltage was applied to generate a corona discharge to charge the surface, the maximum value of the surface potential after 0.3 seconds was 470V, and the surface potential after 10 seconds was 250V. Furthermore, using the measuring device shown in FIG. 3, this roller is set to a temperature of 22 ° C. and a humidity of 50% RH.
When a friction test was carried out using a cloth of 100% cellulose, 30 g / m ² , 70 mesh under the conditions of No. ² , the friction coefficient was 0.20.

When the charging roller was mounted on a printer cartridge and left for 2 weeks at a temperature of 40 ° C. and a humidity of 95% RH, no close contact with the photoreceptor (OPC) was observed. Next, using the above cartridge after being left for two weeks, AC voltage Vpp = 1800V and DC voltage Vdc = −650.
When a picture was drawn with V, only a small amount of fog was seen, but when a picture was drawn with a DC voltage Vdc = -1260V, fog occurred. At this time, when the charging roller was taken out and the toner was wiped off, no toner remained on the roller. Further, even when the continuous 8000 images were printed, no improvement in the image was observed.

[Comparative Example 2] The same intermediate resin layer A having a thickness of 100 μm was formed on the surface of the same elastic layer as in Example 1, and further the outermost resin layer G having a thickness of 10 μm was formed thereon. As a result, a charging roller having a layer structure similar to that shown in FIG.

Outermost resin layer G Polyamide resin "H1060" (Sanyo Kasei) was dissolved in an ethanol solvent, and a coating material prepared by adding 10 parts by weight of a melamine crosslinking agent to 100 parts by weight of the polyamide resin was applied by a dipping method. Formed.

The resistance of the obtained roller is 5 × 10 ⁶ [Ω].
Met. When a voltage of 8 kV was applied to a corona discharger arranged with a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, 0.3
The maximum surface potential after 6 seconds is 6 V, and 10
The surface potential after second was 0.73V. Furthermore, using the measuring device shown in FIG.
100% cellulose under the condition of 0% RH, 30 g / m ² ,
When a friction test was conducted using a 70-mesh cloth, the friction coefficient was 1.88.

When the above charging roller was mounted on a printer cartridge and left at a temperature of 40 ° C./humidity of 95% RH for 2 weeks, adhesion with the photoreceptor (OPC) occurred. Next, using the above-mentioned cartridge before being brought into close contact with OPC, AC voltage Vpp = 1800V and DC voltage Vdc = −650.
When a picture was drawn with V, a good image was obtained. Further, when a picture was drawn at a DC voltage Vdc = -1260V, no initial image fog was seen. At this time, when the charging roller was taken out and the toner was wiped off, the toner remained on the roller severely. Further, when images were continuously printed on 8,000 sheets, fogging caused by toner adhesion and roller surface layer deterioration occurred.

Comparative Example 3 The same intermediate resin layer A having a thickness of 100 μm was formed on the surface of the elastic layer as in Example 1, and the outermost resin layer H having a thickness of 10 μm described below was further formed thereon. As a result, a charging roller having a layer structure similar to that shown in FIG.

Outermost resin layer H Polyamide resin "X1850" (Sanyo Chemical Co., Ltd.) was dissolved in an ethanol solvent, and 20 parts by weight of carbon as a conductive agent was added to 100 parts by weight of the polyamide resin. The coating material added by weight part was applied by the dipping method to form.

The resistance of the obtained roller is 1.5 × 10.
It was ⁶ [Ω]. A charging roller was prepared in the same manner except that the outermost resin layer H was not mixed with carbon as a conductive agent, and a voltage of 8 kV was applied to a corona discharger arranged at a distance of 1 mm from the roller surface. When a voltage was applied to generate corona discharge to charge the surface, the maximum value of the surface potential after 0.3 seconds was 220V, and 10
The surface potential after 90 seconds was 90V. Furthermore, using the measuring device shown in FIG. 3, this roller is heated at a temperature of 22 ° C. and a humidity of 50%.
Cellulose 100%, 30 g / m ² , 70 under RH condition
When a friction test was conducted using a mesh cloth, the friction coefficient was 1.07.

When the above charging roller was mounted on a printer cartridge and left at a temperature of 40 ° C./humidity of 95% RH for 2 weeks, adhesion with the photoreceptor (OPC) occurred. Next, using the above-mentioned cartridge before being brought into close contact with OPC, AC voltage Vpp = 1800V and DC voltage Vdc = −650.
When a picture was drawn with V, a slight fog occurred. Also,
Fog occurred when a picture was drawn at a DC voltage Vdc of -1260V. At this time, when the charging roller was taken out and the toner was wiped off, a large amount of toner remained on the roller. Further, when images were continuously printed on 8,000 sheets, the fog further deteriorated.

Comparative Example 4 The same intermediate resin layer A having a thickness of 100 μm was formed on the surface of the elastic layer as in Example 1, and further the outermost resin layer I having a thickness of 10 μm was formed thereon. As a result, a charging roller having a layer structure similar to that shown in FIG.

Outermost Resin Layer I Polyamide resin "X1850" (Sanyo Chemical Co., Ltd.) was dissolved in an ethanol solvent, and "Modiper F220" (Nippon Oil & Fats Co., Ltd.) composed of a fluorine-acrylic block copolymer was added to 100 parts by weight of polyamide resin. After adding 10 parts by weight, 20 parts by weight of carbon as a conductive agent,
A coating material containing 10 parts by weight of a melamine cross-linking agent was applied by a dipping method to be formed.

The resistance of the obtained roller is 1.5 × 10.
It was ⁶ [Ω]. A charging roller was prepared in the same manner except that carbon as a conductive agent was not mixed with the outermost resin layer I, and a voltage of 8 kV was applied to a corona discharger arranged at a distance of 1 mm from the roller surface. When a corona discharge was generated to charge the surface, the maximum value of the surface potential after 0.3 seconds was 240 V, and 10
The surface potential after 80 seconds was 80V. Furthermore, using the measuring device shown in FIG. 3, this roller is heated at a temperature of 22 ° C. and a humidity of 50%.
Cellulose 100%, 30 g / m ² , 70 under RH condition
When a friction test was conducted using a mesh cloth, the friction coefficient was 0.31.

When the charging roller was mounted in a printer cartridge and left at a temperature of 40 ° C./humidity of 95% RH for 2 weeks, no close contact with the photoreceptor (OPC) was observed. Next, using the above cartridge after being left for two weeks, AC voltage Vpp = 1800V and DC voltage Vdc = −650.
When a picture was drawn with V, a slight fog occurred. Also,
Fog occurred when a picture was drawn at a DC voltage Vdc of -1260V. At this time, when the charging roller was taken out and the toner was wiped off, no toner remained on the roller. Further, 8000 sheets of images were continuously printed, but no improvement of the images was observed.

As described above, Examples 1 to 4 and Comparative Examples 1 to 4
Table 1 below shows a list of the evaluation results.

[Table 1] Evaluation criteria ○: Very good ○ △: Good △: Normal △ ×: Not very good ×: Poor

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view illustrating a charging member according to the present invention.

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

FIG. 3 is a schematic view showing an example of a measuring device for measuring the friction coefficient on the surface of the charging member.

FIG. 4 is a schematic view showing an example of an apparatus for measuring surface charging potential characteristics of a charging member.

[Explanation of symbols]

1 shaft 2 elastic layer 3 surface layer 4 Resistance adjustment layer 5 Charging roller (charging member) 6 Photosensitive drum (charged body) 7 Voltage application means

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H200 FA01 FA02 FA08 FA16 FA18                       FA19 GA16 GA23 GB50 HA02                       HA28 HB12 HB22 HB43 HB45                       HB46 HB47 HB48 LA18 LA23                       LC04 MA03 MA04 MA08 MA14                       MA17 MB01 MB04 MB06 MC01                       MC02 MC05 MC06 MC09 MC11                       MC16 MC18 NA02 NA03 NA08                       NA09                 4J002 BD122 BD142 BD152 BN171                       CL001 CL061 CL072 DA016                       EH077 FD116 GF00 GQ02                       GS00

Claims (6)

[Claims] 1. An elastic layer, which is formed on an elastic layer, in a charging member for charging the charged body by contacting the charged body and applying a voltage between the charged body and the charged body. And at least one resin layer, and the outermost resin layer in contact with the body to be charged contains 50% by weight or more of a polyamide resin and 50% by weight or less of a fluororesin component and / or a fluorine compound component. It is a charging member formed of a resin material contained therein, and in a state where the outermost resin layer does not contain any conductive agent, a voltage of 8 kV is applied to a corona discharger arranged at a distance of 1 mm from the surface of the outermost resin layer. When a voltage is applied to generate corona discharge to charge the outermost resin layer surface, the maximum surface potential after 0.3 seconds is 50 V or less, and the surface potential after 10 seconds is 5 V. Characterized by And a charging member. 2. The content of the polyamide resin in the resin material forming the outermost resin layer is 50 to 99.9% by weight, and the content of the fluororesin component and / or the fluorine compound component is 0.1 to 50.
The charging member according to claim 1, wherein the charging member is wt%. 3. Cellulose 100%, 30 g / m ² , 7
The friction coefficient with respect to the cloth of 0 mesh is 0.5 or less when the cloth is pressed against the cloth with a load of 100 gf.
Or the charging member according to 2. 4. A resin material for molding the outermost resin layer,
The charging member according to claim 1, further comprising a conductive powder. 5. The elastic layer has a density of 0.05 to 0.9 g.
2. A urethane foam of 1 cm ³ / cm ^3.
The charging member according to claim 4. 6. A charging device comprising: a charging member that is in contact with a member to be charged to charge the member to be charged; and a voltage applying unit that applies a voltage between the member to be charged and the charging member. A charging device comprising the charging member according to claim 1 as the charging member.