JP2003167398A - Electrically conductive member and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrically conductive member capable of solving the problems of initial fog, lasting fog and adhesion to OPC (organic photoconductor), capable of reliably performing good developing operation, transfer operation, cleaning operation, etc., even under severe conditions and capable of stably obtaining a good image. <P>SOLUTION: The electrically conductive member used in an electrophotographic apparatus is characterized in that it has an elastic layer and at least one resin layer formed on the elastic layer, and the outermost resin layer making the surface of the member is formed from a resin material comprising ≥50 wt.% urethane resin and ≤50 wt.% polysiloxane component. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive member used in a developing device, a transfer device, a cleaning device or the like used in an electrophotographic device or an electrostatic recording process, and a developing device, a transfer device or a developing device using the conductive member. The present invention relates to an electrophotographic apparatus equipped with a cleaning device.

[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 these processes, first, regarding development, a non-magnetic one-component developer is supplied to a photosensitive drum or the like holding a latent image, and the developer is attached to the latent image on the photosensitive drum to form a latent image. A pressure developing method is known as a developing method for visualization (U.S. Pat. Nos. 3,152,2012 and 37311).
No. 46, etc.), this method does not require a magnetic material, so that the apparatus can be simplified and downsized, and the toner can be colored easily.

In this pressure developing method, as shown in FIG. 2, a developing roller 6 carrying a toner (non-magnetic one-component developer) holds a latent image on a photosensitive drum such as an electrostatic latent image. The development is performed by bringing the toner into contact with the body 5 and adhering the toner to the latent image of the latent image holding body 5. Therefore, the developing roller 6 is in close contact with the latent image holding body 5 such as a photosensitive drum. Must be securely held and rotated, and must be formed of an elastic body having conductivity.

Further, in a transfer device for transferring a toner image developed and visualized with toner from a latent image carrier onto a transfer sheet, conventionally, the transfer sheet is charged by using a corona charger to transfer the toner image onto the transfer sheet. Transfer is generally used, but corona discharge has problems such as generation of ozone and the need for a high-voltage power supply. As a transfer device that solves this problem, there is known a transfer device that charges a transfer paper 8 by using a bias roller (transfer roller) 9 made of conductive rubber, as shown in FIG. In this method, in order to obtain high transfer efficiency and a transferred image without unevenness, a constant nip width is set between the photosensitive drum 5 and the roller,
The pressure between the drums should be low and fairly soft conductive rubber must be used. In the apparatus of FIG. 2, the toner image transferred onto the transfer paper 8 is fixed by the fixing device 13.
Is heated and fixed on the transfer paper 8.

Further, the toner left on the photosensitive drum after the transfer of the toner image is removed by a cleaning device. As the cleaning device, the edge of a blade formed of urethane rubber or the like on a conventional photosensitive member is pressed. Generally, the toner is scraped off. However, when such a blade is used, the frictional force with the photoconductor is large, the driving force is large, the edge is likely to damage the photosensitive drum, and the rubber plate may be damaged when cleaning is not possible. As one of the solutions to such a problem, as shown in FIG. 2, a cleaning roller 11 capable of applying a voltage is used.
There is proposed a cleanerless method in which a cleaning device 12 is configured by using a cleaning roller 11, and the cleaning roller 11 directly removes residual toner from the surface of the photosensitive drum 5 or forcibly charges the toner and collects the toner by a developing roller or the like. ing. This cleaning roller is also required to have the same characteristics as the above-mentioned transfer roller and the like.

Conventionally, as conductive members such as the developing roller, the transfer roller, and the cleaning roller, for example, on the surface of an elastic layer such as rubber or urethane foam, to secure the smoothness of the surface, adjust the resistance, and improve the charging property, Acrylic, urethane, nylon, polyethylene, epoxy, polyester, polyether, polystyrene, phenol, AB
It is known that a resin solution is formed by applying a resin solution of S, polyamide, urethane-modified acrylic resin or the like by a dipping method or a spray method.

[0008]

However, the above-mentioned conventional conductive member has the following problems. [Initial fog / durable fog] In response to the recent demands for higher image quality, lower cost (lower voltage, smaller members, etc.), higher speed, and higher durability in the electrophotographic field, a developing roller,
A conductive member such as a transfer roller or a cleaning roller may cause problems such as: initial image defect (initial fog), and durable image defect (durability fog) caused by stacking prints. However, the root cause of this has not been clarified, and there are currently no clear measures that can be fully satisfied.

[OPC contact] The conductive members such as the developing roller, the transfer roller, and the cleaning roller are the photosensitive member (OP).
Since it is kept in contact with C) for a long period of time, adhesion (adhesion) may occur between the photoconductor and these conductive surfaces, resulting in peeling of the coating film and contamination of the photoconductor. In particular, in recent years, there has been a strong demand for the development of a conductive member, particularly a resin layer on the surface of the member, which is excellent in releasability without coming into close contact with the photoconductor even under severe conditions such as temperature / humidity, etc., in response to demands for multi-environment.

The present invention has been made in view of the above circumstances, and is capable of solving the problems of [initial fog / durability fog] and [OPC adhesion], and good development operation and transfer even under severe conditions. An object of the present invention is to provide a conductive member capable of reliably performing an operation, a cleaning operation, etc. and stably obtaining a good image, and an electrophotographic apparatus using the conductive member.

[0011]

MEANS FOR SOLVING THE PROBLEMS AND BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies to achieve the above object, the present inventor has formed at least one resin layer on an elastic layer, When obtaining a conductive member such as a transfer roller or a cleaning roller, the outermost resin layer forming the surface of the member is 50
1 mm from the surface of the outermost resin layer in the state where the outermost resin layer is formed of a resin material containing not less than 50% by weight of a urethane resin and not more than 50% by weight of a polysiloxane component, and the outermost resin layer does not contain any conductive agent. When a voltage of 8 kV was applied to the corona discharger arranged at intervals of 4 to generate corona discharge to charge the surface of the outermost resin layer, the maximum value of the surface potential after 0.3 seconds was 50 V or less. By setting the surface potential after 10 seconds to be 5 V or less, the above [initial fog / durable fog] and [OP
A developing roller capable of solving the problem of "C adhesion", capable of performing a good developing operation, a transferring operation or a cleaning operation even under severe conditions, and capable of stably obtaining a good image, It has been found that a conductive member such as a transfer roller or a cleaning roller can be obtained.

[Initial fog / durable fog] According to the study by the present inventor, the above-mentioned [initial fog / durable fog] is
Mainly depends on the resin layer of the conductive member, particularly the outermost resin layer. Among them, as for “initial fogging”, in the state where the outermost resin layer of the conductive member does not contain any 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 conductive 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, it is possible to extremely effectively prevent the occurrence of the “initial fog”. As for the "endurance fog", it was found that if the "initial fog" does not occur, it is much more advantageous than the "initial fog" even if there is some deterioration. On the other hand, in order to suppress "durability fog", in addition to the above "surface charging potential characteristic", it was found that the toner adhesion and frictional property of the outermost resin layer of the conductive member are important. That is, if the conductive member such as the developing roller, the transfer roller, or the cleaning roller has a property that the toner adheres much or the toner is hard to be removed, fogging occurs due to toner damage to the conductive member such as toner filming and toner fusion. Will be done. If the outermost resin layer has a high frictional property, the shear stress between the photoconductor and the conductive member becomes excessive, and fogging occurs due to damage such as slack, wrinkles, and holes. Therefore, as a result of further study on this point, when the conductive member is made of 100% cellulose, 30 g / m ² , and 70 mesh cloth and a pressure of 100 gf is applied to the cloth, the friction coefficient to the cloth is 0.5 or less. It has been found that the occurrence of this "durable fog" can be suppressed very effectively when it has friction characteristics.

Here, the reason for evaluating the surface potential characteristics when corona discharge is used as a measure against "fogging" is as follows. That is, "fogging" is a so-called image defect, which is caused by mechanical defects, environmental defects, electrical defects, and defects somewhere such as the developing roller, the transfer roller, and the cleaning roller. The most frequent cause of this is common to all rollers, and electrical failure due to surface residual charge is the most common cause. That is, all of these rollers play their role by applying a voltage, but when no voltage is applied, the presence of residual charge on the surface of the rollers causes electrical non-uniformity when a voltage is applied during operation. Will occur. This electrical non-uniformity appears as a fatal image defect for these conductive rollers, and causes fog such as so-called "white spots", "black spots", "horizontal stripes", and "vertical stripes". Therefore, when this voltage is not applied, the surface residual charge must be eliminated as much as possible. Therefore, the performance of preventing the occurrence of the above "fog" can be evaluated by the surface charge attenuation characteristic accompanying the surface potential measurement by corona discharge. In the present invention, the surface charge attenuation characteristic is evaluated and adjusted. .

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, in a conductive roller such as a developing roller, a transfer roller, or a cleaning roller, it is usual that the resistance increases from the shaft toward the outer layer. There is a reason. Therefore, it can be said that the surface charge permeability of the roller depends substantially only on the surface layer. And, in this surface layer, it may contain a conductive agent, in which case the conductive agent may help the surface charge decay to some extent, but when the conductive agent is a filler, the fillers are microscopically different from each other. Since there is almost no contact, the filler cannot completely prevent the charge from staying in the surface layer resin, and in the end, if the charge permeability of the resin alone is not excellent, there is no residual charge. It cannot be. Further, when the conductive agent is an ionic conductive agent, a concentration gradient of the ionic conductive agent is usually generated in the resin, and a portion in which the ionic conductive agent is hardly present is generated. The charge permeability of a single substance becomes important. Therefore, the charge permeability of the resin alone in the outermost resin layer is the most important parameter, and in the evaluation of surface potential characteristics, it is appropriate to perform the evaluation in the state where the outermost resin layer does not contain any conductive agent. It becomes.

Further, the reason for evaluating the charging potential 10 seconds after the charging by corona discharge is as follows. That is, a large potential of 8 kV (which is considered to be a slightly lower voltage in a conductive roller) is applied to the surface of the conductive roller by corona discharge, but such a large voltage is not normally 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 the good releasability as described above. That is, when the contact angle of water on the outermost resin layer surface is 90 degrees or more, the problem of [OPC adhesion] is effectively solved,
It has been found that it is possible to effectively prevent the occurrence of inconveniences such as coating film peeling and photoreceptor contamination.

By forming the outermost resin layer of a conductive member such as a developing roller, a transfer roller or a cleaning roller with a resin material containing 50% by weight or more of a urethane resin and 50% by weight or less of a polysiloxane component. , The "outer fog / durability fog" problem can be solved, the outermost resin layer having the above-mentioned "surface electrification potential characteristics" can be obtained, and the problem of "durability fog" can be solved more reliably. The outermost resin layer having the above-mentioned "surface contact angle" capable of solving the problems of "characteristics" and "OPC adhesion" can be easily formed, and good development operation, transfer operation, and cleaning can be performed even under severe conditions. The inventors have completed the present invention by finding that a conductive member that can be reliably operated and stably obtains a good image can be obtained.

Therefore, according to the present invention, a conductive member used in an electrophotographic apparatus comprises an elastic layer and at least one resin layer formed on the elastic layer, and constitutes the surface of the member. The outermost resin layer is a conductive member formed of a resin material containing 50% by weight or more of a urethane resin and 50% by weight or less of a polysiloxane component, and the outermost resin layer does not contain any conductive agent. In this state, when a voltage of 8 kV was 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 was charged, 0.3 A maximum value of the surface potential after 50 seconds is 50 V or less, and a surface potential after 10 seconds is 5 V or less, a conductive member,
And an electrophotographic apparatus using the conductive member as a developing member such as a developing roller, a transfer member such as a transfer roller, or a cleaning member such as a cleaning roller.

The present invention will be described in more detail below.
As described above, the conductive member of the present invention comprises the outermost resin layer forming the surface of the member and the urethane resin of 50% by weight or more.
It is formed of a resin material containing a polysiloxane component in an amount of not more than wt%.

The urethane resin used as the resin material for forming the outermost resin layer may be any one that can be formed on the elastic layer which is the base of the conductive member, such as polyether type, polyester type and polyolefin type. It is possible to use various urethane resins such as a polyether ester type.

Although these urethane resins have good electrical and mechanical properties and have favorable physical properties as a skin layer of a conductive member, they also have the disadvantage of high tackiness and large friction. Therefore, in the present invention, by using the polysiloxane component in combination, the above-mentioned problems of tackiness and frictional properties are solved while maintaining the above-mentioned electrical characteristics and mechanical characteristics.

Examples of the polysiloxane component include dimethyl silicone, methylphenyl silicone, methylhydrogen silicone, alkyl-modified silicone, fluorine-modified silicone, polyether-modified silicone, alcohol-modified silicone, amino-modified silicone, epoxy-modified silicone, epoxy-polysilicone. Examples thereof include ether silicone, phenyl-modified silicone, carboxy-modified silicone and the like, and oils or resins thereof can be used.

The outermost resin layer constituting the member surface of the conductive member of the present invention contains the urethane resin and the polysiloxane component as the resin components as described above. In this case, the urethane resin is 50 parts by weight. % Or more, more specifically 50 to 99% by weight, preferably 50 to 95% by weight
And the polysiloxane component is 50% by weight or less, more specifically 1 to 50% by weight, preferably 5 to 50% by weight.
It is what Here, the urethane component is 50% by weight
If it is less than the above range, good electrical and mechanical properties peculiar to the urethane resin may not be obtained, and if the polysiloxane component is too small, the effect of preventing OPC adhesion and toner fusion may not be sufficiently obtained. If the amount is too large, the effect does not change so much, and on the contrary, it may cause a problem such as phase separation.

The urethane resin and the polysiloxane component may be simply blended, or may be chemically bound by a bond such as a graft or a crosslinking agent such as isocyanate, but the latter is particularly preferable. preferable.

The urethane resin is not particularly limited, but it is preferable that the urethane resin has an active hydrogen group at the terminal or side chain and is crosslinked with a polyisocyanate compound or the like. In this case, as the polyisocyanate compound, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HD
I), isophorone diisocyanate (IPDI), phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), cyclohexane diisocyanate, lysine ester triisocyanate, undecane triisocyanate, hexamethylene triisocyanate, triphenylmethane triisocyanate And polymers, derivatives, modified products and hydrogenated products of these isocyanate compounds. Among these, particularly aliphatic or alicyclic isocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, and polymers, derivatives and modified products thereof are preferably used because they are excellent in ozone resistance and heat resistance.

Although not particularly limited, silica powder can be added and compounded in the resin material forming the outermost resin layer, which reduces the contact area and improves 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 10 ⁶ to 10 ¹³ Ω · cm, particularly 10 ⁷ to 10
It is preferably ¹² Ω · cm.

The method for forming the outermost resin layer on the conductive member is not particularly limited, but a paint containing the above-mentioned components is prepared and the paint is applied to the conductive member by a dipping method or a spray method. The method is preferably used.

The thickness of the outermost resin layer is appropriately set according to the form of the conductive member and is not particularly limited, but is usually 50 μm or less, particularly preferably 2 to 30 μm. If it exceeds 50 μm, the outermost resin layer may be hardened and the flexibility of the outermost resin layer may be impaired.

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

The conductive member of the present invention may be any one as long as at least the surface of the member is formed of the outermost resin layer, and its form is roll-like or plate-like depending on the application and the constitution of the electrophotographic apparatus used. It may be in any suitable form such as a block, a sphere, or a brush, and is not particularly limited, but it is usually preferable to use a roll-shaped conductive roller having the outermost resin layer on the member surface. , For example,
As shown in FIG. 1A, a conductive roller in which an elastic layer 2 is formed on the outer circumference of a shaft 1 and the outermost resin layer 3 is formed on the elastic layer 2 can be exemplified.

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 electrophotographic apparatus in which the conductive 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 a mating member such as a photosensitive drum or transfer paper.
Known rubber or resin, or foams thereof (hereinafter,
"Form"). Specifically, polyurethane, silicone rubber, butadiene rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber, acrylic rubber, nitrile rubber, etc. A rubber composition as a base rubber is exemplified.

By adding a conductive agent to the elastic layer 2, conductivity can be imparted or adjusted to a predetermined resistance value. The conductive agent is not particularly limited,
Lauryl trimethyl ammonium, stearyl methyl ammonium, octadodecyl trimethyl ammonium,
Hexadecyltrimethylammonium, modified fatty acid / dimethylethylammonium perchlorate, chlorate, borofluoride, sulfate, ethosulfate salt, benzyl bromide, benzyl chloride, etc. Cationic surfactant such as quaternary ammonium salt, aliphatic sulfonate, higher alcohol sulfate ester salt, higher alcohol ethylene oxide addition sulfate ester salt, higher alcohol phosphate ester salt, higher alcohol ethylene oxide addition phosphate ester salt, etc. anionic surfactants, higher alcohol ethylene oxide, polyethylene glycol fatty acid esters, polyhydric alcohol fatty acid antistatic agent such as a nonionic antistatic agents such as _{esters, NaClO 4, LiAsF 6, LiBF} 4, NaSC
Electrolytes such as metal salts of Group 1 of the periodic table such as Li ⁺ , Na ⁺ and K ⁺ such as N, KSCN and NaCl, or salts of NH ₄ ⁺ , and conductive carbon such as Ketjen black and acetylene black , SAF, ISAF, HAF, FE
Carbon for rubber such as F, GPF, SRF, FT, MT,
Oxidized carbon for color (ink), pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, and metal oxides such as germanium, polyaniline Conductive polymers such as polypyrrole and polyacetylene. In this case, the blending amount of these conductive agents is appropriately selected according to the type of composition and the type of conductive member and is not particularly limited, but usually the volume resistivity of the elastic layer is 10 ⁴ to 10 ^4. It is adjusted to ⁹ Ω · cm, preferably 10 ⁵ to 10 ⁷ Ω · cm.

The thickness of the elastic layer 2 is appropriately set according to the type, form, size, layer structure, etc. of the member and is not particularly limited, but will be described with reference to FIG. In the case of a roll-shaped conductive member as shown in FIG. 1 (B), it is usually preferably 2 to 30 mm, particularly preferably 3 to 20 mm.

Here, when the outermost resin layer 3 is formed by coating the elastic layer 2 with the coating material of the resin material containing the polysiloxane-containing urethane resin as described above, the solvent used for the coating material. May be water-based or solvent-based.

If necessary, an intermediate resin layer 4 may be provided between the outermost resin layer 3 and the elastic layer 2 as shown in FIG. 1 (B). In this case, the resin forming the intermediate resin layer 4 is not particularly limited, but an aqueous resin is preferably used. As the water-based resin, any type may be used as long as the solvent is water, and there are water-soluble type, emulsion type, suspension type and the like, and a resin having active hydrogen such as carboxyl group, hydroxyl group and 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 conductive members, so that the electrostatic capacity also becomes smaller, and the electrical conductivity between the conductive 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 some carbons that have undergone an oxidation treatment also exist, but the carbon that has undergone this oxidation has a slightly increased oxygen content. As the pH increases, 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 the 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 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, a structural viscosity-imparting agent, etc. within a 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 may contain a resin other than the water-based resin, and if necessary, this It is also possible to form a plurality of intermediate resin layers 4.

The method for 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 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 conductive 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, suitable resistance as a conductive member is obtained in any layer structure and application.
Volume resistance is 10 ⁵ to 10 ¹¹ Ωc to obtain a good image
m is preferable, and particularly 10 ⁶ to 10 ¹⁰ Ωcm
Is preferred.

Here, in the conductive member of the present invention, the above outermost resin layer contains no conductive agent (when the outermost resin layer is mixed with the conductive agent, the conductive agent is removed). Except for the above-mentioned conductive member), 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 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 reliably prevent the occurrence of the above-mentioned "fog", particularly the "initial fog". Further, according to the conductive member of the present invention in which the outermost resin layer is formed by using the above polysiloxane-containing urethane resin, such charging potential characteristics can be easily achieved.

Here, by measuring the surface potential of the conductive member,
As a specific method for evaluating the above charging potential characteristics, for example, US QEA (Quality Engineering Associates, I)
nc.) “Charge Roller Test System CRT200
0 "can be used as shown in FIG. That is, the conductive member (conductive roller in the figure) formed with the outermost resin layer is used as the subject roller 21, and both ends of the shaft 22 of the subject roller 21 are fixed to the chuck 23.
A measuring unit 20 having a small scorotron discharger 24 and a surface electrometer 25 provided at a predetermined distance is placed opposite to the surface of the subject roller 21 while keeping a distance of 1 mm. While still, the measurement unit 20 is moved from one end to the other end of the subject roller 21 at a constant speed to measure the surface potential of the subject roller 21 while applying the surface charge to the subject roller 21. The moving speed of 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, standard conditions are normal temperature and normal humidity (22 ° C / 50% R).
Measurement is performed in the atmosphere of H). 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 conductive member of the present invention preferably has a small frictional resistance on its surface, and is not particularly limited, but 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 0.35 or less. This causes "fog",
In particular, it is possible to more reliably prevent the occurrence of "durable fog". Further, according to the conductive member of the present invention in which the outermost resin layer is formed by using the above polysiloxane-containing urethane resin, such surface friction characteristics can be easily achieved.

In this case, the friction coefficient can be measured by the measuring instrument 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) 15 is fixed, and the conductive member 14 of the present invention to be evaluated is placed on the cloth 15 in a state of being contacted, and 100 gf is applied by the pressing means 53. Is applied to bring the cloth 15 and the conductive member 14 into pressure contact with each other, and in this state, the movable stage 52 is moved back and forth to move the friction speed 10
The cloth 15 and the conductive member 14 are frictionally moved at 0 mm / min, and the friction resistance at this time is measured by the load cell 54.
From the frictional resistance value above cloth (Bencott lint free)
The friction coefficient of the conductive member 14 with respect to 15 may be obtained.
In addition, as a friction partner material, cellulose 100%, 30 g
/ M ² , 70 mesh cloth (Bencott lint free)
The reason for selecting was that the surface properties of the conductive members such as the developing member, the transfer member, and the cleaning member were most correlated,
This is because the obtained measurement range of the friction coefficient was appropriate.

Further, the conductive member of the present invention is not particularly limited, but the contact angle with water of the member surface, that is, the surface of the outermost resin layer is 90 degrees or more, particularly 95 degrees or more. It is preferable that the problem of peeling of the coating film and the contamination of the mating member caused by the close contact with the mating member such as the photoreceptor can be solved more reliably, and the outermost layer using the polysiloxane-containing urethane resin According to the conductive member of the present invention in which the resin layer is formed, such a contact angle can be easily achieved.

[0047]

EFFECTS OF THE INVENTION The conductive member of the present invention can solve the problems of [initial fog / durable fog] and [OPC adhesion] described above, and can perform good developing operation, transfer operation, and cleaning even under severe conditions. The operation and the like can be reliably performed, and a good image can be stably obtained by using it as a developing member, a transfer member, a cleaning member, etc. of the electrophotographic apparatus.

[0048]

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] (Developing member) Urethane resin "DP307" (Sanyo Chemical Co., Ltd.) was dissolved in a methyl ethyl ketone (MEK) solvent, and silicone oil "FZ-3711" modified with alcohol at both ends was used as a bifunctional isocyanate. After adding 30 parts by weight of a prepolymerized product to 100 parts by weight of urethane resin, an isocyanate crosslinking agent is further added with NCO.
A paint A was prepared by adding the paint so that the index was 1.5. The contact angle between the sheet formed by drying the coating material A and water was measured and found to be 97 degrees.

A 6 mm thick elastic layer (volume resistivity of 10 ⁵ Ω) made of isoprene rubber having a resistance value adjusted by adding a conductive agent (carbon black) to the outer circumference of the metal shaft.
.Cm) to form an isoprene rubber roller.
By dipping this isoprene rubber roller in the coating material A and drying it, about 1 is applied onto the isoprene rubber elastic layer.
An outermost resin layer A having a thickness of 0 μm was formed to prepare a developing roller having the same layer structure as that shown in FIG.

The surface roughness of the obtained roller was JIS ten-point average roughness Rz of 3.9 μm. In addition, when a voltage of 8 KV was applied to the corona discharger placed at a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, the maximum surface potential after 0.3 seconds was reached. The value is 3 V, and the surface potential after 10 seconds is 0.25.
It was V. 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 was 0.25.

[Example 2] (Developing member) Urethane resin "NX304" (Sanyo Chemical Co., Ltd.) was dissolved in a MEK solvent, and silicone oil "X-22-176F" (Shin-Etsu Silicone) modified with one terminal alcohol was added to 100 wt. After adding 10 parts by weight to parts by weight, 20 parts by weight of silica particles and an isocyanate cross-linking agent were added so that the NCO index was 1.5, to prepare coating material B. The contact angle between the sheet formed by drying the paint B and water and the water was measured and found to be 99 degrees.

An isoprene rubber roller similar to that used in Example 1 was dipped in the coating material B and dried to form an outermost resin layer B of about 10 μm on the isoprene rubber elastic layer of the roller.
To form a developing roller having the same layer structure as that shown in FIG.

The surface roughness of the obtained roller was JIS ten-point average roughness Rz of 5.2 μm. In addition, when a voltage of 8 KV was applied to the corona discharger placed at a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, the maximum surface potential after 0.3 seconds was reached. The value is 20 V, and the surface potential after 10 seconds is 0.3.
It was 2V. 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 was 0.22.

[Comparative Example 1] (Developing member) Urethane resin "DP307" (Sanyo Kasei Co., Ltd.) was dissolved in a MEK solvent, and an isocyanate cross-linking agent was added so that the NCO index became 1.5, whereby a coating material C was prepared. . The contact angle between the sheet formed by drying the paint C and water and water was measured and found to be 80 degrees.

An isoprene rubber roller similar to that used in Example 1 was dipped in the coating material C and dried to form an outermost resin layer C of about 10 μm on the isoprene rubber elastic layer of the roller.
To form a developing roller having the same layer structure as that shown in FIG.

The surface roughness of the obtained roller was JIS ten-point average roughness Rz of 3.0 μm. In addition, when a voltage of 8 KV was applied to the corona discharger placed at a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, the maximum surface potential after 0.3 seconds was reached. The value is 4 V, and the surface potential after 10 seconds is 0.21.
It was V. 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 was 2.18.

Comparative Example 2 (Developing Member) A water-based urethane resin "Superflex 420" (Daiichi Kogyo Seiyaku Co., Ltd.) was appropriately adjusted in concentration to prepare a coating material D. The contact angle between the sheet formed by drying the paint D and water and the water was 77 degrees.

An isoprene rubber roller similar to that used in Example 1 was dipped in the above coating D and dried to form an outermost resin layer D of about 10 μm on the isoprene rubber elastic layer of the roller.
To form a developing roller having the same layer structure as that shown in FIG.

The surface roughness of the obtained roller was 3.2 μm in terms of JIS ten-point average roughness Rz. In addition, when a voltage of 8 KV was applied to the corona discharger placed at a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, the maximum surface potential after 0.3 seconds was reached. The value is 500 V, and the surface potential after 10 seconds is 32.
It was 0V. 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 was 1.58.

[Comparative Example 3] (Developing member) Aqueous urethane resin "Superflex 420" (Daiichi Kogyo Seiyaku Co., Ltd.) was appropriately adjusted in concentration, and dimethyl silicone oil "SH200" (Toray Dow Corning) was added to 100 parts by weight of the urethane resin. 10 parts by weight was added to prepare a coating material E. The contact angle between the sheet formed by drying the coating material E and water was 90 °.

An isoprene rubber roller similar to that used in Example 1 was dipped in the coating material E and dried to form an outermost resin layer E of about 10 μm on the isoprene rubber elastic layer of the roller.
To form a developing roller having the same layer structure as that shown in FIG.

The surface roughness of the obtained roller was 3.8 μm in terms of JIS ten-point average roughness Rz. In addition, when a voltage of 8 KV was applied to the corona discharger placed at a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, the maximum surface potential after 0.3 seconds was reached. The value is 520 V, and the surface potential after 10 seconds is 33.
It was 0V. 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 was 0.45.

With respect to the developing rollers of Examples 1 and 2 and Comparative Examples 1 to 3, OPC adhesion (adhesion) was performed by the following method.
Initial image fog, toner transportability, toner chargeability, image fog after endurance, and development roller abrasion were evaluated. The results are shown in Table 1.

[OPC adhesion (adhesion)] The roller to be tested was mounted as a developing roller on the printer cartridge shown in FIG. 2 and left at 40 ° C./80% RH for 1 week. The adhesion was examined. [Initial image fog] A roller to be tested is mounted as a developing roller on the printer cartridge shown in FIG. 2, a developing bias voltage is set to 400 V, a non-magnetic one-component toner having an average particle size of 7 μm is used, and a peripheral speed of 60 mm / sec. The image was reproduced by reversal development while rotating at a high speed, and the image quality (presence or absence of fog and degree) in each of the initial white background, halftone, and black background images was evaluated. [Toner Conveying Property] The roller to be tested is mounted as a developing roller on the printer cartridge shown in FIG.
The toner conveyance amount was investigated by rotating at a peripheral speed of / sec to form a uniform thin toner layer on the surface of the developing roller, sucking the thin toner layer, and measuring the weight. [Toner chargeability] A roller to be tested is mounted as a developing roller on the printer cartridge shown in FIG.
It was rotated at a peripheral speed of / sec to form a uniform thin toner layer on the surface of the developing roller. The thin toner layer was sucked and introduced into a Faraday gauge, and the amount of charge was measured. [Image Fogging After Durability] After the above-mentioned [initial image fogging] test, a durability test of 10,000 sheets was performed, and then the same image evaluation was performed. [Abrasion of Developing Roller] The tested roller after the durability test was taken out, and the surface of the roller was observed with a video microscope to evaluate the degree of scratches and abrasion.

[0066]

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

[Example 3] (Transfer member) Urethane resin "DP307" (Sanyo Chemical Co., Ltd.) was dissolved in MEK solvent, and silicone oil "FZ-3711" modified with alcohol at both ends was prepolymerized with bifunctional isocyanate. After adding 30 parts by weight to 100 parts by weight of the urethane resin, 20 parts by weight of carbon powder and N as an isocyanate crosslinking agent are added.
A paint F was prepared by adding the CO index to 1.5. The contact angle between the sheet formed by drying the paint F and water and the water was measured and found to be 95 degrees.

On the outer circumference of the metal shaft, a 5 mm-thick elastic layer (volume resistivity of 10 ⁵ ) made of urethane foam whose resistance value was adjusted by adding a conductive agent (carbon black).
Ω · cm) to form a urethane foam roller. This urethane foam roller is dipped in the coating material F and dried to form an outermost resin layer F having a thickness of about 10 μm on the urethane foam elastic layer, as shown in FIG.
A transfer roller having a layer structure similar to that of was prepared.

When a voltage of 8 KV was applied to the corona discharger arranged at a distance of 1 mm from the surface of the obtained roller to generate corona discharge and the surface was charged, 0.3
The maximum value of the surface potential after 9 seconds is 9 V, and 10
The surface potential after one second was 1.32V. In addition, 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 0.18.

[Comparative Example 4] (Transfer member) Aqueous urethane resin "Superflex 420" (Daiichi Kogyo Seiyaku Co., Ltd.) was appropriately adjusted in concentration, and 20 parts by weight of carbon powder was added to 100 parts by weight of the urethane resin. Paint G
Was prepared. The contact angle between the sheet formed by drying the paint G and water and the water was 76 degrees.

A urethane foam roller similar to that used in Example 3 was dipped in the coating material G and dried to form an outermost resin layer G having a thickness of about 10 μm on the urethane foam elastic layer of the roller. A transfer roller having the same layer structure as in (A) was prepared.

A transfer roller was prepared in the same manner except that carbon as a conductive agent was not mixed in the outermost resin layer G, and 8 KV was applied to a corona discharger arranged at a distance of 1 mm from the obtained roller surface. When the voltage was applied to generate corona discharge to charge the surface, the maximum surface potential after 0.3 seconds was 550 V, and the surface potential after 10 seconds was 340 V. Also, 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 1.7
It was 8.

The transfer rollers of Example 3 and Comparative Example 4 were pressed against the photosensitive drum with a load of 1 kg, and the temperature was 50 ° C./humidity was 8
When left in an environment of 5% RH for 2 weeks, the roller of Example 3 did not cause any particular problem, whereas Comparative Example 4
There was sticking and contamination between the roller and the photosensitive drum. Further, when both transfer rollers were set in a laser beam printer and 5,000 sheets of images were printed, no particular problems were found with the roller of Example 3, but with the roller of Comparative Example 4, the toner on the roller surface was Due to stains, blank characters in the image and stains on the back surface of the transfer paper occurred.

[Embodiment 4] (Cleaning member) An elastic layer (1.0 × 10 ³ Ω · c) formed of a conductive urethane foam with a thickness of 3 mm formed on the outer periphery of a metal shaft.
m), the following intermediate resin layer H having a thickness of 100 μm is formed, and further the outermost resin layer I having a thickness of 10 μm is formed on the intermediate resin layer H having the same layer structure as in FIG. 1B. Created a cleaning roller.

The intermediate resin layer H is formed by applying a coating material H containing water-based acrylic resin by a dipping method and having a volume resistivity of 5 × 10 ^7.
Adjusted to Ω · cm. Outermost resin layer I Urethane resin "DP307" (Sanyo Chemical Co., Ltd.) is dissolved in MEK solvent, and silicone resin "FZ-3711" with alcohols at both ends is prepolymerized with bifunctional isocyanate to obtain urethane resin 100. After adding 30 parts by weight to parts by weight, an isocyanate cross-linking agent was further added so that the NCO index became 1.5 to prepare a coating material I, and this coating material I was applied by a dipping method. Further, the contact angle between the sheet obtained by drying the above paint I and water was measured and found to be 97.
It was degree.

The surface roughness of the obtained roller was JIS ten-point average roughness Rz of 0.6 μm. In addition, when a voltage of 8 KV was applied to the corona discharger placed at a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, the maximum surface potential after 0.3 seconds was reached. The value is 4 V, and the surface potential after 10 seconds is 0.18.
It was V. 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 was 0.28.

When the above cleaning roller was attached to a printer cartridge and left for 2 weeks in an environment of temperature 40 ° C./humidity 95% RH, sticking to the photosensitive drum was not observed. In addition, a good image was obtained when an image was printed using the cartridge, and a continuous image was obtained.
No image deterioration was observed even when 0 images were printed.

[Comparative Example 5] (Cleaning member) An intermediate resin layer H similar to that of Example 4 was formed on the surface of an elastic layer similar to that of Example 4, and the following outermost resin having a thickness of 10 µm was further formed thereon. Layer J was formed to prepare a cleaning roller having the same layer structure as that shown in FIG.

Outermost Resin Layer J A coating J prepared by appropriately adjusting the concentration of an aqueous urethane resin "Superflex 420" (Daiichi Kogyo Seiyaku) was applied by the dipping method. Further, the contact angle between the sheet obtained by drying the coating material J and water was 77 °.

The surface roughness of the obtained roller was 0.5 μm in JIS ten-point average roughness Rz. In addition, when a voltage of 8 KV was applied to the corona discharger placed at a distance of 1 mm from the roller surface to generate corona discharge and the surface was charged, the maximum surface potential after 0.3 seconds was reached. The value is 590 V, and the surface potential after 10 seconds is 37.
It was 0V. 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 was 2.2.

When the cleaning roller was attached to a printer cartridge and left for 2 weeks in an environment of temperature 40 ° C./humidity 95% RH, sticking to the photosensitive drum occurred. In addition, when an image was printed using the cartridge, one stripe pattern was contaminated in the lateral direction at the photosensitive drum cycle. Further, in the image display, white background fogging occurred due to poor cleaning.

[Brief description of drawings]

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

FIG. 2 is a schematic view showing an example of an electrophotographic apparatus using the conductive member of the present invention.

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

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

[Explanation of symbols] 1 shaft 2 elastic layer 3 outermost resin layer 4 Intermediate resin layer 5 Photosensitive drum (latent image holder) 6 Developing roller (developing member) 7 Developing device 8 Transfer paper 9 Transfer roller (transfer member) 11 Cleaning roller (cleaning member) 12 Cleaning device 13 Fixer

Continued front page    F-term (reference) 2H071 BA43 DA08 DA09 DA13                 2H077 AD06 FA01 FA13 FA22 FA25                 2H134 GA01 GB02 HA02 HA03 HA17                       KD05 KD07 KD08 KE02 KG08                       KH01                 2H200 FA16 GA23 GA44 GB15 HA03                       HA12 HB03 HB12 HB22 JA02                       JA25 JA26 JA27 JB10 LC03                       MA03 MA04 MA06 MA08 MA17                       MA20 MB04 MC05 MC06                 3J103 AA02 AA14 AA32 AA51 BA41                       CA03 FA18 GA02 GA57 GA58                       HA04 HA20 HA48 HA54

Claims (9)

[Claims] 1. A conductive member used in an electrophotographic apparatus, comprising an elastic layer and at least one formed on the elastic layer.
The outermost resin layer, which comprises the resin layer of the layer, and which constitutes the surface of the member, comprises 50% by weight or more of urethane resin and 50% by weight.
A conductive member formed of a resin material containing the following polysiloxane component, and arranged at a distance of 1 mm from the surface of the outermost resin layer in a state where the outermost resin layer does not contain any conductive agent. 8k for a corona discharger
When a voltage of V is applied 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 10 seconds is 5 V or less. Is a conductive member. 2. The conductive member according to claim 1, wherein the content of the urethane resin in the resin material forming the outermost resin layer is 50 to 95% by weight and the content of the polysiloxane component is 5 to 50% by weight. 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 conductive member according to 2. 4. The contact angle of the outermost resin layer surface with water is 9
The conductive member according to any one of claims 1 to 3, which is at least 0 degree. 5. The resin material forming the outermost resin layer,
A bifunctional or higher functional isocyanate crosslinking agent is contained.
The conductive member according to any one of items 1 to 4. 6. A resin material for molding the outermost resin layer,
The conductive member according to claim 1, further comprising a conductive powder. 7. A developer is carried on the surface of the conductive member according to claim 1 to form a thin film of the developer, and an electrostatic latent image is held on the surface in this state. An electronic device comprising a developing device for visualizing the electrostatic latent image by bringing the developer into contact with the latent image carrier to adhere the developer to the electrostatic latent image on the surface of the latent image carrier. Photographic equipment. 8. A transfer device for charging the transfer paper with the conductive member according to claim 1 and transferring the developer from the electrostatic latent image visualized by the developer onto the transfer paper. An electrophotographic apparatus characterized by the following. 9. An electrophotographic apparatus comprising a cleaning device for removing the developer remaining on the latent image holding member by the conductive member according to claim 1. Description: