JP3437627B2 - Conductive roller 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 roller for charging an object to be charged such as a photosensitive drum and a recording medium to a predetermined polarity by a contact charging method in an electrophotographic recording apparatus and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art An electrophotographic recording apparatus widely used in a copying machine, a laser beam printer, etc., is generally equipped with a drum-shaped photosensitive member (hereinafter referred to as photosensitive drum),
The photosensitive drum is charged and exposed to form an electrostatic latent 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 or the like. The recording medium is transferred to another recording medium for transfer, and then the photosensitive drum is 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, whereby a series of recording operations is completed.

A charging roller that applies a predetermined potential to the photosensitive drum of the electrophotographic recording apparatus, a developing roller that conveys toner to the photosensitive drum, and a predetermined potential with respect to the recording medium conveyed to the transfer region. A conductive roller such as a transfer roller that imparts a charge or a charge-eliminating roller that equalizes the charged area of the photosensitive drum after transfer to a constant potential is usually a good conductive shaft and a good conductive rubber provided on the outer periphery thereof. And a conductive film that covers the base layer to adjust the electric resistance of the roller and prevent contamination of the photosensitive drum and the recording medium.

As the conductive film, the conductive carbon is dispersed in a conventional thermosetting rubber such as epichlorohydrin or thermoplastic polyurethane, and the volume resistance can be used as a conductive roller 1.0 × 10 ⁷ -1. 0.0 × 10 ¹¹ Ω
Those adjusted to cm are used, and a conductive film is formed by applying these on the base layer by a wet coating method such as electrostatic coating, dipping, or a roll coater.

[0005]

However, the wet coating methods such as electrostatic coating, dipping, and roll coater require a plurality of organic solvents or have a film thickness suitable for the application of the conductive roller. Since it requires complicated operations such as having to perform the application work once,
The step of forming these conductive films is one of the factors that increase the manufacturing cost of the conductive roller. Furthermore, if the adhesion between the conductive film and the base layer is poor, wrinkles or kinks may occur in the film, which may adversely affect the image.

The present invention has been made in view of the above circumstances, and provides a method of manufacturing a conductive roller which simplifies the process of forming a conductive film and reduces the manufacturing cost of the conductive roller, and further, the conductive method. The aim is to avoid wrinkles and kinks in the membrane.

[0007]

In order to achieve the above object, the present invention has the following constitution. The conductive roller of the present invention is a conductive roller having a shaft, a conductive base layer provided on the outer circumference of the shaft, and a conductive film provided on the outer circumference of the conductive base layer, wherein It is characterized in that the conductive film is composed of a plurality of layers, and the underlying layer is a conductive adhesive layer.

Preferably, the conductive film has a temperature of 25.
Volume resistance of 1.0 x 10 at 50 ° C and relative humidity of 50% RH
^{6 to} 1.0 × 10 ¹³ Ωcm. More preferably,
The conductive adhesive layer has a temperature of 25 ° C. and a relative humidity of 50% RH.
The volume resistance value at is 1.0 × 10 ¹³ Ωcm or less.

In the method of manufacturing a conductive roller of the present invention, a conductive film composed of a plurality of layers is simultaneously extruded to form a shrink tube, which is then cut into a predetermined length, and the outer circumference of the conductive base layer is covered with heat treatment. And the conductive film is formed.

The present invention will be described in more detail below.
FIG. 1 shows an example of the conductive roller of the present invention, which is used as a charger of an electronic copying machine. This conductive roller is made of stainless steel, plated iron,
A base layer 2 made of a conductive elastic material is provided on the outer periphery of a shaft 1 made of a good conductive material such as brass or conductive plastic.
And a conductive film 3 composed of a plurality of conductive layers (two layers) is formed on the outer peripheral surface of the base layer 2 by a shrink tube.

Here, as the elastic material having conductivity which constitutes the base layer 2, a non-foamed or foamed conductive rubber composition and a conductive polyurethane foam mixed with a conductive material can be used.

In this case, as the rubber component constituting the non-foamed conductive rubber composition, nitrile butadiene rubber, chloroprene rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber (EPDM), isoprene rubber, polynorbornene rubber, etc. Ordinary rubbers or thermoplastic rubbers such as styrene-butadiene-styrene (SBS) and styrene-butadiene-styrene water additive (SEBS) can be used, but these rubbers are not particularly limited. In particular, it is preferable to mix solid butadiene rubber / liquid polyisoprene rubber at a ratio of about 10/90 to 50/50, and to mix the conductive material with the conductive material to form the base layer 2, which results in low hardness and compression. The base layer 2 with less permanent strain can be obtained, and the roller and the photosensitive drum can be charged. It is possible to improve the adhesion between.

The foamed conductive rubber is not particularly limited, but ethylene propylene rubber (EP
DM), chloroprene, a mixture of chlorosulfonated polyethylene with a conductive material, a foam of a copolymer rubber of epichlorohydrin and ethylene oxide, or a foam of a mixture of a copolymer rubber of epichlorohydrin and ethylene oxide with a conductive material is preferable. Can be used.

As the conductive material to be added to these rubber compositions, conductive powder such as carbon black, graphite, metal, various conductive metal oxides (tin oxide, titanium oxide, etc.), carbon fiber, metal oxide, etc. Various conductive fibers such as short fibers of the above can be used. The compounding amount is 3 to 100 parts by weight, particularly 5 to 50 parts by weight based on 100 parts by weight of all rubber components.
The volume resistance of the base layer 2 is preferably adjusted to about 10 ¹ to 10 ⁹ Ωcm. The base layer 2 can be formed by a known vulcanization molding method, and the thickness thereof is appropriately set depending on the application of the roller and the like, but is usually 1 to 20 mm.

The conductive roller of the present invention has the base layer 2
The conductive film 3 formed above is formed in a plurality of layers via a shrink tube. In this case, the thermoplastic resin applied to the layers other than the conductive adhesive layer below the conductive film 3 may be any extrudable thermoplastic resin.・ Atochem Japan Co., Ltd. product name Pebax 4011, M
X1723, MX1074, MX1041, MX179
7. Mitsui DuPont Polychemical Co., Ltd. product name Alkulin, Dainichiseika Co., Ltd. product name Rezamin, Ube Industries, Ltd. product name PAE1200, PAE1202, or styrene resin, vinyl chloride resin, olefin resin, polyester resin Resin, polyamide resin, urethane resin, polyethylene, polypropylene, urethane nylon, ABS, EVA, fluororesin, polycarbonate, polystyrene and the like can be mentioned. Among these, Pebax 4011, Arculin, PAE1200, PAE
1202 is preferably used, but Pebax 40 is particularly preferable.
11. Alculin itself has a volume resistance value of 1.0 × 10 ^{5 to} 1.0 × 10 ¹² Ωcm, which is suitable as a conductive film of a conductive roller, and can be used as it is without adjusting the conductivity. This is particularly preferable because it can be performed. Resamine, PAE1200, PAE1202, etc.
It is necessary to add a conductive material to adjust its electric resistance, but the adjustment range is 1.0 × 10 ⁵ to 1.0 × 10 ^5.
It can be set to ¹² Ωcm, and in this case, as the conductive material, a general conductive material such as titanium oxide, carbon, conductive tin oxide or the like can be used.

Here, examples of the material of the conductive adhesive layer below the conductive film include urethane-based, nylon-based, vinyl acetate-based, and olefin-based hot melt adhesives, and the volume resistance value in this case is 1. It is preferably not more than 0.0 × 10 ¹³ Ωcm.

Further, for example, the apparatus shown in FIG. 2 can form the desired number of conductive films 3 by one operation.
2 (a) is for 2 types and 2 layers, (b) is for 2 types and 3 layers,
(C) is for 3 types and 3 layers. In addition, after cross-linking the roller consisting only of the base layer formed by molding the rubber or foamed rubber into a thick tube by the molding machine through the heating tank from the molding machine,
It is also possible to manufacture a conductive roller by coating a conductive film through a shrink tube having a predetermined length, inserting the shaft in the center of the base layer, and fixing the shaft with an adhesive if necessary.

[0018]

EXAMPLES Examples of the present invention will be described below. (1) When the structure of the conductive film is the resistance adjustment upper layer / conductive adhesion lower layer, the resistance adjustment layer may be made of resin whose material itself has an appropriate resistance value, or carbon, conductive metal oxide, etc. A resin having a resistance value adjusted by mixing conductive powder may be used. At this time, the adhesion between the resistance adjusting layer and the base layer is poor, and the film may be wrinkled or twisted. In particular, when the film expands due to heat or humidity, it tends to wrinkle. These wrinkles and kinks naturally affect the image on the printer. Therefore, two layers of thermoplastic resin (which becomes a so-called hot melt adhesive) capable of adhering the base and the resistance adjusting film are extruded simultaneously with the resistance adjusting layer, and the base roller or the hose-shaped base is covered with a shrink tube and heated to shrink. At the same time, the adhesive layer is melted and adhered to the base roller. In this case, the adhesive lower layer may be provided, and the upper layer may be a single layer or multiple layers.

<Example> Polyether block amide elastomer (PAE12
00U; Ube Industries, Ltd.) 15 carbon black (Ketjenblack EC; Lion Akzo Co., Ltd.)
Part KCK kneading machine (made by KCK Co., Ltd.) was mixed. In addition, thermoplastic polyurethane for hot melt adhesion (E78
0P128; Nippon Miractolan Co., Ltd.) was mixed with 25 parts of Ketjen Black EC using a KCK kneader. Two Brabender φ20 extruders (Toyo Seiki Co., Ltd.) were used and doubled from one crosshead (adhesive layer inside) into hot water at 97 ° C. into a glass tube with an inner diameter of 14 mm.
The mixture was extruded under an internal pressure of 6 kg / cm ² , cooled and wound up.
Thus, the outer diameter is 13 mm, the thickness of the thermoplastic polyurethane layer (conductive adhesive layer) is 10 μm, and the PAE1200U
A shrink tube having a layer (resistance adjustment layer) of 100 μm in thickness was obtained. A hose-shaped foam rubber having an inner diameter of 5 mm and an outer diameter of 11.5 mm was cut into a length of 225 mm and a core metal having a length of 240 mm and a diameter of 6 mm was inserted. 230 of the above shrink tube
The product cut into mm length was covered and heat-treated at 135 ° C. for 15 minutes to shrink the film, and the hot-melt adhesive layer was melted and adhered to the sponge rubber.

If this charging roller is used as an LBP (laser beam printer; laser jet 2-P manufactured by Hured Packard), no gap is formed between the film and the sponge, wrinkles do not occur, and a good image is obtained. Met. The electric resistance of the roller (base layer) is, as shown in FIG. 3, a conductive roller 4 and a copper plate 5 having a width of 1 cm on the outer peripheral surface.
Is applied, a voltage of 1000 V is applied between the shaft 1 and the copper plate 5, and the resistance value R is calculated from the current value I at this time by the formula R
= V / I

[0021]

As described above, according to the present invention, a process of forming a conductive film, which conventionally requires a plurality of coating steps and drying steps using an organic solvent, and requires a lot of labor and cost. It is possible to efficiently perform a simple operation even with a plurality of layers, effectively reduce the manufacturing cost of the conductive roller, and improve the working environment. Further, since the shrink tube is formed in a state where a desired plurality of layers are laminated at one time and is covered on the base layer, the number of steps is small and the cost can be reduced accordingly. Also, by forming the conductive film with a plurality of layers, it is possible to easily embody a conductive roll that can satisfy various required characteristics. Furthermore, since the lower layer of the conductive film is a conductive adhesive layer, the adhesion with the base layer can be improved, and as a result, wrinkles and kinking of the conductive film can be prevented and the effect on the image can be improved. It becomes possible to

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a conductive roller obtained by a manufacturing method of the present invention.

FIG. 2 is a partial cross-sectional view of an extrusion molding machine that can be preferably used in the manufacturing method of the present invention.

FIG. 3 is a schematic perspective view illustrating a method for measuring electric resistance.

[Explanation of symbols]

1 shaft 2 base layer 3 Conductive film

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-3-239277 (JP, A) JP-A-3-284749 (JP, A) JP-A-60-13524 (JP, A) JP-A-63- 2399 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16C 13/00 G03G 15/02 101 G03G 15/08 501

Claims (4)

(57) [Claims] 1. A conductive roller having a shaft, a conductive base layer provided on the outer circumference of the shaft, and a conductive film provided on the outer circumference of the conductive base layer, wherein the conductive film is A conductive roller comprising a plurality of layers and a conductive adhesive layer as a lower layer. 2. The conductive film has a temperature of 25 ° C. and a relative humidity of 5
Volume resistance value at 0% RH 1.0 × 10 ^{6 to} 1.0 × 10
The conductive roller according to claim 1, wherein the conductive roller has a resistance of ¹³ Ωcm. 3. The conductive adhesive layer has a volume resistance value of 1.0 × 10 ¹³ Ω at a temperature of 25 ° C. and a relative humidity of 50% RH.
The conductive roller according to claim 1 or 2, wherein the conductive roller has a size of not more than cm. 4. The method of manufacturing a conductive roller according to claim 1, wherein a conductive film composed of a plurality of layers is simultaneously extruded to form a shrink tube,
A method for manufacturing a conductive roller, which comprises cutting the conductive base layer to a predetermined length, heat-treating the conductive base layer to form the conductive film.