JPH07164571A - Charged roller - Google Patents

Abstract

PURPOSE:To preform an inexpensive, stabilized and uniform charging for a long period of time. CONSTITUTION:In a charged roller 103 comprising a core material 101 and a surface elastic layer 102, epichlorohydrin rubber is mixed with butadiene rubber, and then vulcanization molded to form the surface elastic layer 102 and to form a charged roller 103 without requiring a troublesome coating process of the surface layer. The stabilized charging can be performed for a long period of time by using a material mixed with inadhesive rubber (butadiene rubber) for the surface elastic layer 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging roller used in a contact charging device, and more particularly to a charging roller having a core material and a surface elastic layer.

[0002]

2. Description of the Related Art In image forming apparatuses such as electrophotographic copying machines, printers, and facsimile machines, corona dischargers are widely used as charging means for uniformly charging the entire surface of a photoconductor. This corona discharger is effective as a means for uniformly charging the photoconductor to a certain potential, but it requires a high-voltage power source to perform corona discharge, and ozone is generated with the discharge. When a large amount of ozone is generated, it not only adversely affects the environment, but also causes a problem that the charging member and the photoconductor are deteriorated by ozone.

As shown in FIG. 2, the charging roller 201 is brought into contact with the photosensitive drum 202 and driven and rotated by the corona discharger, and a voltage is applied to the core metal 203 of the charging roller 201 from a power source 204. A charging roller that charges the surface of the moving body drum 202 has been put into practical use. The charging roller 201 as the charging means has an advantage that the voltage of the power supply 204 can be reduced and the amount of ozone generated due to the charging process is small. It also has the advantage that it does not require electrostatic attraction of dust associated with the use of corona electrode wires and does not require a high-voltage power supply.

As a conventional charging roller, there is a conductive rubber roller in which conductive particles such as carbon black, metal powder, and metal oxide are dispersed in a metal core material. Also,
As a non-dispersed conductive rubber that does not use conductive particles, for example, as disclosed in JP-A-1-142569,
A charging roller using epichlorohydrin rubber as a surface elastic layer has been proposed.

Furthermore, as disclosed in Japanese Patent Laid-Open No. 64-073364 and Japanese Patent Laid-Open No. 1-211799,
A two-layer or three-layer structure is formed on the core material by providing a resistance layer of a nylon resin on the conductive rubber roller or using a non-adhesive coating of fluororesin as in JP-A-58-194061. Those with have been proposed.

[0006]

However, in the rubber roller in which the above-mentioned conductive particles are dispersed, it is necessary to increase the amount of conductive particles dispersed in order to maintain its low resistance. There are problems such as increased strain, uneven resistance due to unevenness and dispersion of conductive particles, and uniform charging due to local leakage current.

When epichlorohydrin rubber is used as the surface elastic layer, the toner on the surface of the charging roller is not sufficiently released from the toner, so that the toner slightly adhering to the surface of the photosensitive member is transferred to the charging roller to cause uneven charging. However, there is a problem in that it may occur or it may be difficult to secure a stable charging potential in the long term.

On the other hand, although a charging roller provided with a resistance layer of nylon resin or a non-adhesive coating of fluororesin can secure stable uniform charging for a long period of time, the surface layer coating process is Since it is necessary, there is a problem that the production process becomes complicated, resulting in high cost.

The present invention has been made in view of the above, and an object of the present invention is to make it possible to perform stable uniform charging at low cost for a long period of time.

[0010]

In order to achieve the above object, the present invention provides a charging roller having a core material and a surface elastic layer, wherein the surface elastic layer is formed after mixing epichlorohydrin rubber and butadiene rubber. The present invention provides a charging roller formed by vulcanization molding.

[0011]

In the charging roller of the present invention, the epichlorohydrin rubber and the butadiene rubber are mixed and then vulcanized and molded to form the surface elastic layer, so that the charging roller can be formed without a complicated coating process of the surface layer. It is formed.

[0012]

EXAMPLES For the charging roller of the present invention, three examples (Example 1, Example 2 and Example 3) prepared by changing the compounding ratio of epichlorohydrin rubber and butadiene rubber will be described below, and for comparison, A detailed description will be given based on three comparative examples (Comparative Example 1, Comparative Example 2, Comparative Example 3).

Each of Examples 1 to 3 has the surface elastic layer shown in Table 1. As shown in FIG. 1, the surface elastic layer 102 is formed by vulcanizing and molding φ6 onto the core material 101, and then performing cylindrical polishing. To obtain a charging roller 103 of φ12. The charging rollers of Comparative Examples 1 to 3 were also formed in the same manner.

[0014]

[Table 1]

Comparative Example 1 is an example using only butadiene rubber, which is excellent in releasability from the toner and does not migrate to the surface of the charging roller, but a sufficient charging potential cannot be obtained due to high resistance. It was

Further, Comparative Example 2 is an example in which carbon, which is a conductive particle, is dispersed in butadiene rubber to reduce the resistance. In this case, unevenness of the conductive particles, leakage current due to variations, and charging unevenness are caused. There has occurred.

Comparative Example 3 is an example in which only epichlorohydrin rubber is used. The epichlorohydrin rubber is a non-dispersed medium resistance rubber, but the toner slightly remaining or adhering to the surface of the photoreceptor sticks to the surface of the charging roller. Transferred to the surface of the charging roller depending on the property, and uneven charging occurred over time.

In Examples 1 to 3, the epichlorohydrin rubber and the butadiene rubber were mixed and kneaded and then vulcanized and molded, so that the epichlorohydrin rubber having a medium resistance and the butadiene rubber having excellent releasability were uniformly mixed, and sufficient charging was performed. It was possible to obtain a charging roller that was stable with respect to potential and time. The blending ratio of epichlorohydrin rubber / butadiene rubber is such that the volume resistivity of the surface elastic layer is 1 in order to obtain a sufficient charging potential.
Since it is desirable that it be less than or equal to × 10 ¹⁰ , the printer 10
The weight ratio of 3 to the epichlorohydrin rubber was 50% or less.

Table 2 shows the rubber compounding of the surface elastic layer of Example 1. The pace polymer was epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (trade name Epichromer CG, manufactured by Daiso), polybutadiene (trade name). (BR01, manufactured by JSR) was mixed and kneaded according to the composition shown in Table 2, followed by vulcanization at 150 ° C. for 40 minutes, and then cylindrical grinding to prepare a charging roller of Example 1.

[0020]

[Table 2]

As described above, according to the first to third embodiments, the surface elastic layer is formed by using a mixture of non-adhesive rubber without dispersing conductive particles. It is possible to obtain an inexpensive charging roller that is composed of only an elastic layer and is capable of stable uniform charging for a long period of time.

[0022]

As described above, the charging roller of the present invention is inexpensive and stable for a long time because the surface elastic layer is formed by vulcanization molding after mixing epichlorohydrin rubber and butadiene rubber. Uniform charging can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a charging roller of Examples 1 to 3.

FIG. 2 is an explanatory view showing a conventional charging device using a charging roller.

[Explanation of symbols]

 101 Core Material 102 Surface Elastic Layer 103 Charging Roller

Claims (1)

[Claims] 1. A charging roller having a core material and a surface elastic layer, wherein the surface elastic layer is formed by vulcanization molding after mixing epichlorohydrin rubber and butadiene rubber. Charging roller.