JPH07152222A - Electrifying member and electrifying device - Google Patents

Abstract

PURPOSE:To obtain an electrifying member which realizes not only power saving and decrease in ozone production but also reduction of noise and hardly causes melt sticking of a toner on a image carrier body by arranging particles of a specified particle size in an area near the contact part of the electrifying member to the material to be charged. CONSTITUTION:This electrifying member consists of a base body 2 having proper conductivity and a surface layer 4 joined to the base body 2. The surface layer 4 contains particles near the surface of the contact part to the material to be charged. The particles have 35 to 100mum particle size. If the particle size is <35mum, noise is hardly improved, and if it exceeds 100mum, problems such as worsening of the melt sticking property of the toner are caused. These particles are either insulating or conductive particles. When insulating particles are used, it is necessary to cover the surface of the electrifying member with a conductive coating film or an elastic material so that the insulating particles are not exposed to the outermost surface of the member. As for conductive particles, conductive polymers such as polyamine, metal particles and composite particles coated with metal are used. As for insulating particles, acryl resin or the like is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member and a charging device for charging an object to be charged such as a photoconductor used in electrophotography and electrostatic recording processes in copying machines, printers and the like.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic process in a copying machine, the surface of a photoconductor is first uniformly charged, and an image is projected from the optical system on the photoconductor to erase the charge in the light-exposed portion. In this way, a latent image is formed, and then toner is attached and the toner image is transferred to paper to perform copying.

In this case, the corona discharge method is generally adopted for the operation of initially charging the photosensitive member. However, this corona discharge method requires application of a high voltage of 5 to 10 kV, which is not preferable from the viewpoint of safe maintenance of the machine. Further, since the ozone in the corona discharge, the harmful substances such as NO _X occurs, there are also environmental issues.

Therefore, by charging a charging member to which a voltage is applied as described in JP-A 1-205180 and 1-211779 to a charged body such as a photoconductor, the charged body is charged. The method of making it proposed is proposed. According to such a contact charging method, charging can be performed with a lower applied voltage as compared with the corona discharge method, and
Generation of ozone is very small, and there is a possibility that various problems of the corona discharge method can be solved.

However, recently, in the contact charging method, when a conductive rubber roller in which conductive particles such as carbon are dispersed is used, noise is generated when an AC voltage is applied and the photosensitive drum directly contacts the photosensitive member. It has become clear that problems such as deterioration of toner fusing characteristics occur.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. In addition to power saving and reduction of ozone generation, noise is further reduced, and toner fusion to an image carrier is prevented. An object of the present invention is to provide a small number of charging members and a charging device using the charging members.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been earnestly studied in order to achieve the above object, and as a result, it is contacted with an object to be charged and a voltage is applied between the object and the object to be charged. In the charging member for charging the body, by disposing particles having a particle size of 35 to 100 μm in the vicinity of the surface of the contact portion of the charging member with the body to be charged, not only power saving and reduction of ozone generation but also noise The present invention provides a charging member that reduces toner fusion to an image carrier and a charging device using the charging member.

The particles used for the charging member of the present invention have a particle size of 35 to 100 μm. When the particle size is less than 35 μm, noise is hardly improved, and when the particle size exceeds 100 μm, the toner fusing property is deteriorated. It causes problems such as

The amount of the particles is not particularly limited, but is preferably 3 to 50 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the polymer forming the coating film or the elastic body. If the amount exceeds 50 parts by weight, problems such as workability occur.

Further, the particles used in the charging member of the present invention may be particles having an insulating property or a conductive property. In the case of insulating particles, it is necessary to dispose the insulating particles so as to cover the outermost surface of the charging member with a conductive coating film or an elastic material. The conductor particles are
Examples thereof include conductive polymers such as polyaniline, polypyrrole, polyfuran, and polythiophene, metal particles, and composite particles in which the surfaces of the particles are coated with carbon, metal, metal oxide, or the like. Examples of the insulating particles include acrylic resin, nylon resin, epoxy resin, silica, calcium carbonate and the like. Further, among them, acrylic resins and nylon resins are preferable, and cross-linking type acrylic resins are particularly preferable from the viewpoint of forming a coating film because they are unlikely to undergo changes such as swelling, shrinkage, and deformation.

[0011]

The present invention will be described in more detail below.

The shape of the charging member of the present invention is not particularly limited, but may be various shapes such as a roll shape, a plate shape, a square block shape, a spherical shape, a brush shape, etc., but is usually a roll shape or a plate. It is preferable to make the shape. Further, a charging device using the charging member of the present invention is also shown in FIG.
The present invention is not limited to this, and can be changed as appropriate.

The charging roll of the present invention is generally shown in FIGS.
As shown in FIG. 5, a skin layer having particles arranged near the surface of the contacting portion of the charging member with the body to be charged is bonded onto a base body (base body 2 in FIG. 1) made of a material having appropriate conductivity. However, the substrate may have a multilayer structure of two or more layers. Examples of the material of the substrate include metal, urethane, natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone, styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, etc., and carbon black as appropriate. A conductivity-imparting agent such as

The elastic layer used in the present invention is not particularly limited. For example, butadiene rubber (BR), isoprene rubber (IR), urethane rubber (U), ethylene propylene rubber (EPM, EPDM), silicone rubber ( Q), chloroprene rubber (CR), nitrile rubber (N
BR), polynorbornene rubber, butyl rubber (IIR)
Various rubbers such as those to which conductive particles are added are used, and as the conductive particles, metal oxide particles such as carbon black, tin oxide particles, and titanium oxide can be used.

The coating film used in the present invention is not particularly limited, but for example, nylon, polyester, acrylic modified urethane resin, phenol resin, polyamide,
Various resins such as epoxy resin, urea resin, and urethane resin to which conductive particles are added are used. As the conductive particles, carbon black, tin oxide particles, metal oxide particles such as titanium oxide may be used. it can. Further, these resins may be contained alone, or two or more kinds of these resins may be mixed and used.

Further, the particles of the present invention are arranged within a depth of 1000 μm from the outermost surface of the charging member, preferably within a depth of 100 μm, and more preferably within a depth of 50 μm. is necessary. The vicinity of the surface of contact with the photoconductor means the outermost layer when the charging member is in the form of a roll, and the one side which contacts the photoconductor when it is in the form of a plate. Further, the particles may be arranged not only in a part of the charging member but also in the whole.

The method of arranging the particles is not particularly limited,
For example, in the case of forming a coating film, the particles may be previously mixed with the coating material and applied to the charging member at the same time when the coating film is formed. Further, as another method, there is a method of forming a coating film or an elastic layer by melt coating, extrusion or the like. In this case, particles may be blended in these materials in advance.

[0018]

FIG. 3 is a schematic view of an image forming apparatus using the charging device of the present invention. (1) Configuration of Image Forming Apparatus 6 is an image carrier as a drum type electrophotographic photosensitive member, and rotates in the direction of arrow a at 100 mm / sec. A voltage applying unit P applies a voltage obtained by superimposing an AC voltage on a DC voltage to the charging roller 5 as a charging member to uniformly charge the photoconductor. An electrostatic latent image is formed on the photosensitive drum by scanning exposure with a semiconductor laser or exposure 7 with an LED, a halogen lamp or the like. The latent image is visualized as a toner image by the developing device 8, then transferred to a transfer material 10 such as paper by a transfer roller or a transfer pole 5, and discharged as a print through a fixing unit 13.

(2) Structure of Charging Roller In the charging roller of this embodiment, as shown in the sectional views of FIGS. 1 and 2, two or three layers are sequentially formed around a core metal 1 of iron, SUS or the like. Although it is applied to a multi-layer structure, it is also applicable to a charging roller having a single-layer structure. The substrate 2 in FIG. 1 is made of urethane rubber, urethane foam or ethylene-
The conductive elastic layer is made conductive by dispersing conductive carbon in propylene rubber. Layer 2 in FIG. 2 is a conductive elastic layer made conductive by dispersing conductive carbon in butadiene rubber or isoprene rubber.
Layer 3 is a resistance layer, and is a resistance value controlled by dispersing conductive carbon in urethane rubber. On the layer 2 in FIG. 1 and the layer 3 in FIG. 2, a skin layer (layer 4) to which the particles of the present invention are added is provided as a coating layer. In this embodiment, the charging roller shown in FIG. 1 will be examined.

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.

(Example 1) N-methoxymethylated nylon 6 (manufactured by Teikoku Kagaku Sangyo Co., Ltd.) was previously added to methanol as a solvent.
100 phr, titanium oxide 80 p conductive particles
Further, 10 phr of cross-linked acrylic particles MR50G (manufactured by Soken Chemical Industry Co., Ltd.) having a particle diameter of 40 to 60 μm were added to obtain a dispersion liquid. This dispersion was applied by a dip method to a roller provided with a conductive elastic layer of polyurethane foam in which carbon black was added to a metal core bar to prepare a roller-shaped charging member as shown in FIG.

This charging member is attached to the image forming apparatus shown in FIG. 3, the charging sound is measured, and regarding the toner fusion,
The image condition after printing 6000 sheets was evaluated. The evaluation of the toner fusion property is quantified, and the larger the value, the better the image condition. The results are shown in Table 1.

[Table 1]

(Example 2) In Example 1, the particle size was 60
A charging roller was prepared in the same manner except that a crosslinked acrylic particle MR60G (manufactured by Soken Chemical Industry Co., Ltd.) having a particle size of 80 μm
Similar evaluation was performed.

(Example 3) In Example 1, the particle size was 38
A charging roller was prepared in the same manner except that Nylon particle ORGASOL ES-4 (manufactured by Rilsan Japan Co., Ltd.) having a particle size of up to 42 μm was used and the same evaluation was performed.

(Example 4) In Example 1, the particle size was 40
A charging roller was prepared in the same manner except that silica having a particle size of up to 90 μm was used, and the same evaluation was performed.

(Comparative Example 1) In Example 1, the particle size is 3 to
A charging roller was prepared in the same manner except that the crosslinked acrylic particles MR7G (manufactured by Soken Scientific Co., Ltd.) having a size of 10 μm were used, and the same evaluation was performed.

Comparative Example 2 A charging roller was prepared in the same manner as in Example 1 except that the particles were removed, and the same evaluation was performed.

(Comparative Example 3) In Example 1, the particle size was 11
A charging roller was prepared in the same manner except that calcium carbonate of 0 to 250 μm (manufactured by Maruo Calcium Co., Ltd.) was used, and the same evaluation was performed.

[0029]

As described above, according to the charging member of the present invention, in addition to the conventional problems of power saving and reduction of ozone generation, noise is further reduced, and toner for the image carrier is reduced. Since the charging member with less fusion can be provided, the present charging member and the charging device can be widely used in electrophotography and electrostatic processes such as copying machines and printers.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a charging roller of the present invention.

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

FIG. 3 is a schematic view showing an example of an image forming apparatus using the charging device of the present invention.

[Explanation of symbols]

 1 core metal 2 conductive elastic layer 3 resistance layer 4 skin layer 5 charging roller 6 image carrier 7 exposure 8 developing device 9 transfer pole 10 transfer material 11 cleaning member 12 cleaning blade 13 fixing section

Claims (4)

[Claims] 1. A charging member which is brought into contact with a member to be charged and which is charged by applying a voltage between the member and the member to be charged, and a surface of a contact portion of the charging member with the member to be charged. A charging member characterized in that particles having a particle diameter of 35 to 100 μm are arranged in the vicinity thereof. 2. The charging member according to claim 1, wherein the particles are a cross-linking type acrylic resin. 3. A charging device comprising: a charging member that contacts an object to be charged and charges the object; and a voltage applying unit that applies a voltage between the object and the charging member.
A particle size of 35
A charging device, characterized in that particles of -100 μm are arranged. 4. The charging device according to claim 3, wherein the particles are a cross-linking type acrylic resin.