JPH06161216A - Electrifying member - Google Patents

Abstract

PURPOSE:To reduce fluctuation in resistance value at high temp. and high humidity, to prevent the generation of discharging electric breakdown of a photosensitive body of an electrophotographic device and to obtain a clear picture by forming a covering layer with a specified resin component as a substrate. CONSTITUTION:The electrifying member 1 is constituted such that a conductive/ elastic layer 3 is formed on the outside periferal surface of a shaft-like supporting body 2 and a covering layer 4 is formed on the outside peripheral surface of a conductive/elastic layer 3. The covering layer 4 is made of a base material consisting of a resin component contg. N-alkoxy methylated nylon and an insulating resin. As an insulating resin, polyolefine resin dispersion, silicon resin dispersion, nylon resin is uswed for instance. As a N-alkoxy methylated nylon, N-methoxy methylated nylon is usally used. The covering layer 4 is formed by lamination of the conductive/elastic layer 3 by a dipping method. In this case, a conductive material or other filler is dipersed in the covering layer 4, as necessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member which comes into contact with an object to be charged and applies a potential of a predetermined polarity to the member. More specifically, it is possible to ensure an extremely good charging operation even under high temperature and high humidity conditions. The present invention relates to a charging member that can be used for development charging of an electrophotographic recording device, primary charging, transfer charging, charge removal, and the like.

[0002]

2. Description of the Related Art An electrophotographic recording apparatus widely used in a copying machine, a laser beam printer, etc. is generally provided with a drum-shaped photosensitive member (hereinafter referred to as a photosensitive drum). , The photosensitive drum is charged and exposed to form an electrostatic image, and then toner is attached and developed according to the latent image on the photosensitive drum, and then the toner on the photosensitive drum is used for recording paper, etc. The recording medium is transferred to another recording medium for transfer, the photosensitive drum is then discharged to a predetermined potential, and the toner remaining on the photosensitive drum is cleaned to prepare for the next recording. Further, the toner carried on the recording medium by the transfer is melted and pressure-bonded to be fixed on the recording medium, thereby completing a series of recording operations.

Charging means for applying a predetermined potential to the charged area of the photosensitive drum of this electrophotographic recording apparatus, transfer means for applying a predetermined potential to the recording medium conveyed to the transfer area, or after transfer. As a charge eliminating means for uniformizing the charged area of the photosensitive drum to a constant electric potential, a corona charging method which is conventionally configured to generate a corona discharge by applying a high voltage of several hundred to several thousand volts to a thin wire is used. Things are generally adopted.

However, in the case of using such a corona charging system, active molecules such as ozone generated by corona discharge deteriorate the photosensitive drum and other parts, leading to deterioration of the image. There is a possibility that the human body may be adversely affected, and there is also a problem in terms of maintenance such as risk of electric shock due to high voltage, stain on the wire, and disconnection.

Therefore, recently, a method of charging the photosensitive drum by bringing a charging member to which a voltage is applied into contact with the photosensitive drum has been proposed. According to such a contact method, charging can be performed at a lower applied voltage than that of the corona discharge method, and there is almost no generation of active molecules such as ozone, and the charging problem that can solve the problems of the corona discharge method. It is attracting attention as a method.

Conventionally, as a charging member used in the contact charging system, a charging roll in which a conductive elastic layer is formed on the outer circumference of a good conductive shaft has been known. In the meantime, a voltage, especially a voltage obtained by superimposing an AC voltage on a DC voltage is applied to apply a potential to the surface of the photosensitive roll. In the case of such a contact charging method, in order to adjust the electric resistance value of the charging roll to a predetermined value, that is, in order to obtain a desired charging potential by giving a predetermined potential to the photosensitive drum by the charging roll obtaining a predetermined voltage, In addition, in order to prevent the toner from being fused to the photosensitive drum and contaminating the photosensitive drum, a conductive elastic layer is formed on the coating layer made of N-alkoxymethylated nylon film in which a conductive material such as carbon is dispersed to adjust the conductivity. It is generally formed on a layer.

However, such a charging roll is
The resistance value changes greatly depending on the environment, and especially in high temperature and high humidity, the resistance value changes greatly, and an image defect may occur due to dielectric breakdown of the photosensitive drum. This phenomenon is 32
It may occur even under high temperature and high humidity within a normal use range of about 85 ° C. and 85% RH, which is one of the major problems to be solved in the electrophotographic process using the contact charging method.
Is one.

The present invention has been made in view of the above circumstances, and reduces the deterioration of the performance due to the environment, especially the fluctuation of the resistance value under high temperature and high humidity as much as possible, and discharge insulation of the photoreceptor in the electrophotographic apparatus. An object of the present invention is to provide a charging member capable of reliably preventing breakage and surely obtaining a clear image.

[0009]

In order to achieve the above object, the present invention provides a support having good conductivity, and a conductive elastic layer having a single layer or a multilayer structure formed on the support. In a charging member having a coating layer formed on the conductive elastic layer and contacting an object to be charged to give a potential of a predetermined polarity to the member, the coating layer is insulating from N-alkoxymethylated nylon. Provided is a charging member, which is a layer comprising a resin component containing a resin as a base material.

That is, the present inventor reduces the deterioration of performance due to the environment, especially the fluctuation of the resistance value under high temperature and high humidity as much as possible, when performing the charging operation by the contact charging method, and the photosensitive member in the electrophotographic apparatus is reduced. In order to obtain a charging member that can surely prevent discharge breakdown of the body and surely obtain a clear image, pay attention to the coating layer that is in direct contact with the body to be charged, and charge it with various coating layers. When a member was prepared and its charging performance was evaluated, N-alkoxymethylated nylon such as N-methoxymethylated nylon was mixed with an insulating resin such as a polyolefin resin or a silicone resin,
A charging member having a coating layer using this as a base material can reliably prevent the occurrence of discharge dielectric breakdown even under high temperature and high humidity, and can charge the photoconductor well, and reliably obtain a clear image. The inventors have found that the above can be achieved and completed the present invention.

The present invention will be described in more detail below.
As described above, the charging member of the present invention has a conductive elastic layer formed on a good conductive support, and the conductive elastic layer further has an N layer.
-A coating layer having a resin component as a base material containing an alkoxymethylated nylon and an insulating resin is formed, and specifically, the charging member 1 shown in FIG. 1 can be exemplified. That is, reference numeral 1 in the figure shows an example of the charging member of the present invention, in which a conductive elastic layer 3 is formed on the outer circumference of a shaft-shaped support 2, and a coating layer 4 is further formed on the outer circumference of the conductive elastic layer 3. It was formed. Then, as shown in FIG. 2, the charging member 1 is rotated while its surface is brought into close contact with the photosensitive drum (member to be charged) 5, and a power source 6 is provided between the charging member 1 and the photosensitive drum 5. The surface of the photoconductor roll 4 is charged to a predetermined polarity by applying a direct current or a voltage obtained by superimposing an alternating current on the direct current.

Here, as the good conductor forming the support 2, a metal such as steel, stainless steel, brass, or a conductive plastic can be used, but the good conductor is not limited thereto.

The conductive elastic layer 3 is not particularly limited, but is made of a metal such as aluminum or iron, a conductive polymer such as polyacetylene, polypyrrole, polyaniline, carbon, a conductive metal oxide, or the like. It may be formed of rubber, plastic elastomer, or plastic foam in which a conductive material is dispersed and conductively treated. The conductive elastic layer 3 is not particularly limited, but its volume resistance value is preferably 10 ³ to 10 ¹⁰ Ω · cm. Furthermore, the conductive elastic layer 3 may be a layer made of a single material, or a two-layer structure having a base material layer and a layer for adjusting the resistance value. .

The charging member of the present invention comprises the conductive elastic layer 3
A coating layer 4 is formed on which a resin component containing N-alkoxymethylated nylon and an insulating resin is used as a base material. In this case, any insulating resin can be used as long as it has good insulating properties and can be mixed with N-alkoxymethylated nylon, but it can be mixed with N-alkoxymethylated nylon. Since the coating layer 4 can be easily formed by an easy method such as dipping, a material soluble in a solvent such as methanol or water in which N-alkoxymethylated nylon is soluble is preferably used. Specifically, water-dispersed polyolefin resin, water-dispersed silicone resin, nylon resin and the like can be exemplified. As N-alkoxymethylated nylon,
Normally N-methoxymethylated nylon is used, but N
It is also possible to use other N-alkoxymethylated nylons such as ethoxymethylated nylon.

The coating layer 4 is based on a mixture of N-alkoxymethylated nylon and one or more of the above insulating resins. In this case, the N-alkoxymethylated nylon is used. The mixing ratio of the insulating resin and the insulating resin is not particularly limited, but is 100/10 to 100/150 (N
-Alkoxymethylated nylon / insulating resin), especially 1
It is preferably from 00/10 to 100/100, and if it deviates from this range, the variation of the resistance value under high temperature and high humidity becomes large, and there is a possibility that dielectric breakdown of a charged body such as a photoreceptor occurs.

The coating layer 4 is laminated on the conductive elastic layer 3 by a usual method such as a dipping method. In this case, a conductive material or other filler is dispersed in the coating layer 4 as needed. You can also let it. In this case, examples of the conductive material include metals such as aluminum and iron, conductive polymers such as polyacetylene, polypyrrole, and polyaniline, carbon, conductive metal oxides, and metal oxides subjected to conductive treatment. Further, as the filler having no conductivity, it is possible to use a normal filler, but particularly those which prevent the charging failure under low temperature and low humidity and the effect of the present invention to help the effect of the present invention. A material that can more reliably prevent a charging failure due to dielectric breakdown of an object to be charged under high humidity is preferably used. As such a filler, SiO ₂ , TiO ₂ , ZrO ₂ or other metal oxides or A composite metal oxide or the like is preferably used.

The conductive material and other fillers can be dispersed in the coating layer 4 in the form of particles or fibers. In this case, the amount of dispersion is 5 to 150% by weight, particularly 10 to 10. It can be 70% by weight. The film thickness of the coating layer 4 is not particularly limited, but is usually 5 to
The thickness is about 100 μm, and particularly preferably 10 to 60 μm.

The charging member of the present invention is preferably used for any purpose as long as it charges a body to be charged to an electric potential of a predetermined polarity. In particular, an electrophotographic apparatus such as a laser beam printer or a copying machine. It is preferably used as a primary charging member, and in this case, a clear image can be surely reproduced by preventing the occurrence of dielectric breakdown of the photoconductor even under high temperature and high humidity conditions.

The charging member of the present invention is not limited to the roll shape shown in FIGS. 1 and 2, and its form is roll, pool, square block, spherical or brush depending on the application. Although it may be in various forms such as a shape, it is usually preferably in a roll shape or a brush shape. Further, the method of contact with the body to be charged during the charging operation, the means for applying the voltage, and the like are not limited to those shown in FIG. 2, and can be appropriately changed according to the form and application of the charging member.

[0020]

The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 4] 6 as a good conductive support
A φ steel shaft was used, and a conductive urethane foam layer was then formed as a conductive elastic layer on the outer periphery of the shaft by a formulation. That is, 100 parts (weight part, the same below) of polyether polyol (Exenol 828, manufactured by Asahi Glass Co., Ltd.) having a molecular weight of 5000 by adding propylene oxide and ethylene oxide to glycerin, 1,4-butanediol (manufactured by Toyo Soda Co., Ltd.) ) 7.5 parts, urethane modified MDI (Sumitomo Bayern, Sumidule PF) 50
Part, silicon-based surfactant (manufactured by Nippon Unicar Co., SZ1
618) 1.5 parts, 0.58 parts of toluenesulfonic acid salt of 4,8-diazabicyclo [5,4,0] undecene-7 as a catalyst and 0.0015 parts of dibutyltin dilaurate, average particle size 2.5 μm, carbon 50 parts of natural graphite (manufactured by Nippon Graphite Co., Ltd., high-purity AOP) with a content rate of 99% is mixed and foamed with a foaming and pouring machine manufactured by MONDOMIX, and this foam is injected into a cylindrical mold to make the outer circumference of the shaft electrically conductive. A urethane foam layer was formed to obtain a 12φ cylindrical roller.

Next, with respect to 1000 parts of methanol, N--
Alkoxymethylated nylon (manufactured by Teikoku Chemical Industry Co., EF
-30T) 100 parts, self-emulsifying polyolefin 25
40% by weight aqueous solution (Sumitomo Seika, Saixen A)
Methanol solution added in the range of 0 part (N-alkoxymethylated nylon / polyolefin = 100 / 10-1)
00/150) and the above roll was dipped and dried to form a coating layer having a thickness of 15 μm on the conductive urethane foam layer to obtain five types of roll-shaped charging members shown in Table 1.

A laser beam printer (Laser Jet, manufactured by Hewlett-Packard Co.) is used as the charging member.
III Si), and the image was evaluated when a pinhole of 1 mm was opened on the photoconductor under high temperature and high humidity of 32 ° C. and 85% RH. The results are shown in Table 1.

COMPARATIVE EXAMPLE By dipping the roll into a methanol solution of N-alkoxymethylated nylon without adding the self-emulsifying polyolefin and drying,
A charging member was obtained in the same manner as in Example except that a coating layer having a thickness of 15 μm was formed.

Using the charging member thus obtained, an electrophotographic image was obtained in the same manner as in Example 1 and the obtained image was evaluated. The results are shown in Table 1.

[0026]

[Table 1]

As is clear from the results shown in Table 1, N
It is recognized that the charging member of the present invention having the coating layer containing the alkoxymethylated nylon and the insulating resin can obtain a good image even under high temperature and high humidity.

[0028]

As described above, according to the charging member of the present invention, the deterioration of the performance due to the environment, especially the fluctuation of the resistance value under high temperature and high humidity is reduced as much as possible, and the photoconductor in the electrophotographic apparatus is reduced. Surely prevent the occurrence of discharge dielectric breakdown of
A clear image can be surely obtained in the electrophotographic process. This not only means that the applied voltage is resistant to fluctuations, but also can increase the degree of freedom in designing the electrophotographic system, and its economic effect is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a charging member according to an embodiment of the present invention.

FIG. 2 is a schematic view illustrating an operation when charging a photosensitive drum using the charging member.

[Explanation of symbols]

 1 Charging Member 2 Shaft (Support) 3 Conductive Elastic Layer 4 Coating Layer 5 Photosensitive Drum (Charged Object) 6 Power Supply

Claims (1)

[Claims] 1. A support having good conductivity, a conductive elastic layer having a single layer or a multilayer structure formed on the support, and a coating layer formed on the conductive elastic layer. In a charging member that contacts an object to be charged and applies a potential of a predetermined polarity to it,
A charging member characterized in that the coating layer is a layer comprising a resin component containing N-alkoxymethylated nylon and an insulating resin as a base material.