JP3291087B2 - Conductive member and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive member and a method for manufacturing the same, and more particularly to a conductive member suitable for a charging device in electrophotography and a method for manufacturing the same.

[0002]

2. Description of the Related Art In electrophotography, conventionally, a high voltage is applied to a metal wire, and a photoreceptor is charged by a corona generated. However, this order in the corona charging scheme to mar the surface of the photoreceptor by corona products such as ozone and NO _x during corona generation, image white spots and black streaks had image quality problems such as occur.

Therefore, a method has been proposed in which a conductive roll is brought into contact with a photoreceptor and charged. However, since the conductive elastic body constituting the conductive roll is formed by filling a conductive material with a conductive fine powder such as carbon black in a rubber material, the conductive fine powder is often not uniformly dispersed. For this reason, when a voltage is directly applied, a pinhole-shaped conduction circuit is generated due to dielectric breakdown, and a leak current (hereinafter, referred to as pinhole leak) flows, so that there is a disadvantage that charging is stopped. In addition, when the conductive elastic body is deformed by pressure, the contact state between the conductive fine powders (particles) changes,
The electric resistance greatly fluctuates, and as a result, the photosensitive member is charged unevenly, and the image quality is similarly deteriorated.

[0004] In order to solve such problems, a conductive paint is applied on a conductive elastic body to provide a surface layer. That is, on a conductive elastic body made of foamed conductive rubber, a surface layer made of a urethane resin paint in which a conductive pigment is dispersed, and the urethane resin paint has a low molecular weight uncured component and a polymer A charging member composed of two types of thermoplastic urethane resin has been proposed (JP-A-4-184371). When a conductive roll is prepared using this charging member, pinhole leak can be prevented from occurring because the surface is uniformly charged, and a good image can be obtained.

[0005]

However, the charging member requires the urethane resin coating of the surface layer to be formed from a low molecular weight uncured component and a high molecular weight thermoplastic urethane resin. However, there is a disadvantage that the manufacturing cost is increased. The present invention has been made in order to solve such a problem, and a pinhole leak does not occur, and a conductive member which can obtain an image excellent in quality and can be manufactured at low cost. It is an object of the present invention to provide a manufacturing method thereof.

[0006]

The conductive member of the present invention comprises:
Formed from a conductive elastic body filled with conductive fine powder, having an affinity for the conductive fine powder in a solvent for swelling this elastic body and breaking the chain of conductive fine powder. It is characterized in that a surface layer formed by immersing an elastic body in a solution in which a thermosetting low-molecular compound for keeping the conductive fine powder separated is dissolved is provided.

Further, the method for producing a conductive member according to the present invention comprises:
The conductive fine powder conductive elastic body formed by filling a, to a solution formed by dissolving the thermosetting low-molecular compound having an affinity for the conductive fine powder in the solvent which swells the elastic member It is characterized by immersing, followed by heat treatment to disperse the solvent on the surface of the conductive elastic body and to cure the thermosetting low-molecular compound.

The conductive fine powder used in the present invention includes, in addition to carbon black, fine powder of metal such as zinc and nickel, and fine powder of metal oxide such as zinc oxide, tin oxide and titanium oxide. .

Examples of the elastic body filled with such conductive fine powder include BR (butadiene rubber), SBR (styrene / butadiene rubber), NBR (butadiene acrylonitrile rubber), epichlorohydrin rubber, epichlorohydrin
Rubbers such as phosphorus / ethylene oxide rubber and urethane rubber; thermoplastic elastomers such as polyether amide and styrene-polyisoprene; and polyether polyols and polyester polyols which are polyurethane precursors;
Synthetic resins such as polybutadiene polyol are exemplified.

As a solvent for swelling the elastic body, B
For hydrocarbon rubbers such as R and SBR, it is hexane, toluene, etc. For rubbers such as NBR, epichlorohydrin rubber, epichlorohydrin / ethylene oxide rubber, urethane rubber, etc., it is close to a matrix material such as ethyl acetate, tetrahydrofuran, etc. A solvent having an SP value,
There is N-methylpyrrolidone and the like for the thermoplastic elastomer.

Examples of the thermosetting low molecular weight compound having an affinity for the conductive fine powder include isocyanate compounds such as MDI and TDI and epoxy resin compounds.

On the other hand, in order to apply a solution obtained by dissolving the above-mentioned thermosetting low-molecular compound in the above-mentioned solvent to the conductive elastic body, it is necessary to use a dipping method and immerse the conductive elastic body in a tank containing the solution. It is suitable.

The heat treatment of the conductive elastic body coated with the above solution is performed by heating in a hot air drying oven, or by performing infrared heating or high frequency heating to disperse the solvent with heat energy, The curable low molecular weight compound is cured.

[0014]

The surface of the conductive elastic body is swollen by the solvent of the applied solution. Thereby, the chain of the conductive fine powder (particles) on the surface side is broken. On the other hand, by the heat treatment,
The solvent is scattered, and at the same time, the thermosetting low-molecular compound is cured on the surface side, so that the chain of the conductive fine powder is immobilized while being broken. Therefore, since the conductive fine powder is uniformly dispersed on the surface (layer) of the conductive elastic body, there is no occurrence of pinhole leak, and good image quality is obtained when used as a conductive roll or the like. can get. In addition, since the volume resistance of the surface layer is larger than the volume resistance of the conductive elastic body, even when a leak due to a surface defect occurs, the line-shaped defect, that is, a black band or a white band is not formed, and the image quality of only the defective portion is reduced. Can be stopped.

[0015]

Embodiment 1 FIG. 1 is a sectional view of a conductive roll to which a conductive member according to the present invention is applied. The conductive roll comprises a shaft 1 made of stainless steel and a conductive rubber layer 2 provided thereon.
And a surface layer 3 further provided thereon. The shaft 1 has a diameter of 6 mm and a length of 240 mm. The rubber layer 2 is formed with an outer diameter of 12 mm, and is provided on the peripheral surface of the shaft 1 other than both ends at 7.5 mm.

A method for manufacturing the conductive roll having the above configuration will be described. 20 phr of conductive carbon black (trade name: Ketjen Black EC, manufactured by Lion Corporation) is added to EPDM rubber, and this EPDM rubber is provided on a shaft 1, vulcanized in a mold, and polished. To form

On the other hand, 10 parts by weight of an MDI-based polyisocyanate (trade name: MR400, manufactured by Nippon Polyurethane Co., Ltd.) was added to 90 parts by weight of toluene to prepare a solution for surface treatment.

Next, the solution was kept at 20 ° C., and the conductive rubber layer 2 was immersed in the solution together with the shaft 1 for 30 seconds to swell the surface of the conductive rubber layer 2.

Next, the conductive rubber layer 2 was put together with the shaft 1 in an oven heated to 100 ° C. for 10 hours to disperse the toluene and heat-harden the MDI-based polyisocyanate to form the surface layer 3.

Example 2 The above-mentioned conductive carbon black was used as conductive rubber material.
A conductive roll shown in FIG. 1 was produced by the same method as in Example 1 using a polyurethane rubber to which phr was added and using ethyl acetate as a solvent instead of toluene.

Comparative Example 1 A solution obtained by forming a conductive rubber layer 2 on a shaft 1 from the conductive polyurethane rubber of Example 2 and dissolving methoxymethylated nylon (methoxylation rate 25%) in a methanol solvent. Was applied to the conductive rubber layer 2, and heated and cured to produce a conductive roll having a 10 μm surface layer.

Comparative Example 2 The solution of Comparative Example 1 was applied to the conductive rubber layer 2 of Comparative Example 1,
Similarly, a conductive roll having a surface layer of 20 μm was prepared.

Next, the above Examples 1 and 2 and Comparative Examples 1 and 2
Each of the conductive rolls obtained in (1) was incorporated in an electrophotographic copying machine as a charging means, and the image characteristics were evaluated. The room conditions were 5 ° C × 20% RH, 22 ° C × 50% RH, 35 ° C × 85.
% RH, and an evaluation test was performed. As a result, when the conductive rolls of Examples 1 and 2 were used, good images were obtained under all room conditions. On the other hand, when the conductive roll of Comparative Example 1 was used, a pinhole leak occurred in all cases, and a desired image could not be obtained. Comparative Example 2
When the conductive roll of No. 5 was used, poor charging occurred under the condition of 5 ° C. × 20% RH, and an unclear image was obtained. Under other conditions, good images were obtained.

FIG. 2 is a graph showing a change in volume resistivity with respect to a voltage applied to the conductive roll in a logarithmic manner. In this figure, the conductive roll obtained in Example 1 had the change shown in (A), and the conductive roll obtained in Example 2 had the change shown in (B). The conductive roll obtained in Comparative Example 2 has the change shown in (C), and the conductive roll in which only the conductive rubber layer 2 is provided on the shaft has the change shown in (D). Was. Further, in this figure, a region L indicates a range of an appropriate volume resistance value when used as a charging roll, and a region M indicates a range of an appropriate volume resistance value when used as a phenomenon roll. Therefore, as is apparent from this figure, the conductive rolls obtained in Examples 1 and 2 are very excellent as charging and phenomenon rolls.

The conductive member of the present invention can be applied to a transfer roll and a charging blade.

[0026]

As described above, according to the present invention,
It is possible to provide a conductive member capable of inexpensively manufacturing a conductive roll or the like capable of obtaining an image excellent in quality without generating pinhole leak, and a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a sectional view of a conductive roll according to the present invention.

FIG. 2 is a relationship diagram showing a change in volume resistance efficiency with respect to an applied voltage between the conductive roll according to the present invention and that of a comparative example.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16C 13/00 G03G 15/02 101

Claims (2)

(57) [Claims] 1. A conductive member formed of a conductive elastic body filled with conductive fine powder, which is used as a solvent for swelling the elastic body to break a chain of the conductive fine powder. A surface layer formed by immersing the elastic body in a solution in which a thermosetting low-molecular compound for retaining the separation of the conductive fine powder has affinity for the conductive fine powder. Is provided. 2. A method conductive fine powder conductive elastic body formed by filling, with respect to the conductive fine powder in a solvent for separating said conductive fine chain to swell the elastic body Immerse in a solution obtained by dissolving a thermosetting low-molecular compound to maintain the separation of the conductive fine powder with affinity , and then heat-treat to remove the solvent on the surface of the conductive elastic body. A method for producing a conductive member, comprising scattering the thermosetting low-molecular compound while scattering the compound.