JPH0658325A - Manufacture of conductive roll - Google Patents

Abstract

PURPOSE:To simplify a forming process and reduce the cost of manufacturing by conductive the extrusion molding of thermoplastic resin on a base layer, forming a conductive film layer. CONSTITUTION:An approximately ringlike metallic cap 4 at whose peripheral wall an extrusion passage 4a is formed, is used, and through its hollow portion inside, a roll 6 at whose shaft outer periphery a base layer 2 is formed, is passed, and thermoplastic resin 5 is formed into a tube shape through the extrusion passage 4a, and is pushed out onto the base layer 2. A conductive film layer 3 can be formed by moving the roll 6 in one direction and covering the whole surface of the base layer 2 outer peripheral surface by means of thermoplastic resin 5. After the covering of the conductive film layer 3, in a case in which close adhesiveness to the base layer 2 is bed, adhesiveness can be improved by conducting the heat treatment of the roll 6. The thickness of the conductive film layer 3 can be controlled by changing the sending out or receiving speed of the roll 6, and a conductive roll whose outer diameter at the center portion is larger than those at both end portions can be manufactured easily and inexpensively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductive roll for applying an electric potential of a predetermined polarity to an object to be charged such as a photosensitive drum or a recording medium in an electrophotographic recording apparatus or the like. The present invention relates to a method for manufacturing a conductive roll, which can manufacture the conductive roll simply and inexpensively.

[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 a 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 roll for applying a predetermined potential to the charging area of the photosensitive drum of the electrophotographic recording apparatus, a developing roll for transferring the toner to the photosensitive drum, and a predetermined potential for the recording medium transferred to the transfer area. A conductive roll such as a transfer roll for imparting a charge, or a charge removing roll for uniformizing 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 layer that covers the base layer for the purpose of adjusting the electric resistance of the roll and preventing contamination of the photosensitive drum and the recording medium.

For the conductive film layer, a conductive carbon is dispersed in a conventional thermosetting rubber such as epichlorohydrin or thermoplastic polyurethane, and its volume resistance can be used as a conductive roll of 1.0 × 10 ⁷ -1. 0.0 × 10 ¹¹ Ω
The material adjusted to cm is 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.

Further, the base layer is polished so that the outer diameter of the central portion of the roll is larger than the outer diameters of both ends of the roll by polishing the conductive layer, coating the conductive layer repeatedly, increasing or decreasing the number of dippings, etc. The contact width (hereinafter referred to as the nip width) of the photosensitive roll with respect to the photosensitive drum is made uniform along the axial direction of the roll, whereby the charging potential is made uniform.

[0006]

However, in the wet coating method such as electrostatic coating, dipping, and roll coater, a plurality of layers are required in order to require an organic solvent or to have a film thickness according to the use of the conductive roll. Since a complicated operation such as having to perform a single coating operation is required, the step of forming these conductive film layers is one of the reasons for increasing the manufacturing cost of the conductive roll.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a conductive roll, which can simplify the process of forming a conductive film layer and reduce the manufacturing cost of the conductive roll. To do.

[0008]

In order to achieve the above object, the method for producing a conductive roll according to the present invention comprises a conductive film, a shaft, and a conductive base layer provided on the outer periphery of the shaft. When a conductive roll having a conductive film layer provided on the base layer and applying a potential of a predetermined polarity to the charged body while contacting the charged body, a thermoplastic resin is used. By molding the conductive film layer by an extrusion molding method which is a relatively simple method, the manufacturing cost of the conductive roll is reduced.

In addition, in this case, when the thermoplastic resin is extruded on the base layer of the roll to form the conductive film layer, the thickness of the conductive film layer is changed by changing the speed of feeding or taking out the roll. It is possible to easily and inexpensively manufacture a conductive roll that is thin at both ends of the roll and thick at the center of the roll and has an outer diameter at the center of the roll larger than outer diameters at both ends of the roll.

That is, according to the method of manufacturing a conductive roll of the present invention, the formation of the conductive film layer is extruded by using a thermoplastic resin instead of the wet coating method, which has been one of the causes for increasing the manufacturing cost. By performing the molding method, the thermoplastic resin can be directly extruded into a tubular shape on the base layer to form the conductive film layer very simply, and the delivery or take-up speed of the roll during extrusion can be changed. Thus, the thickness of the conductive film layer can be easily controlled. As a result, it is possible to efficiently perform the conductive film layer forming process, which has conventionally required a plurality of coating steps and drying steps using an organic solvent, which requires a lot of labor and cost, by a simple operation. Therefore, the manufacturing cost of the conductive roll can be effectively reduced, and the working environment can be improved.

The present invention will be described in more detail below. As described above, the manufacturing method of the present invention is for manufacturing a conductive roll in which a conductive base layer is provided on the outer periphery of the shaft and a conductive film layer is formed on the surface of the base layer, for example, as shown in FIG. It is intended to manufacture a conductive roll having the exemplified constitution.

That is, FIG. 1 shows an example of a conductive roll obtained by the manufacturing method of the present invention, which is used as a charger of an electronic copying machine. This conductive roll is a shaft 1 made of a good conductive material such as stainless steel, plated iron, brass and conductive plastic.
A base layer 2 made of a conductive elastic material is provided on the outer periphery of
Further, the conductive film layer 3 made of a thermoplastic resin having conductivity is formed on the outer peripheral surface of the base layer 2 by coating.

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 butazine rubber, chloroprene rubber, styrene butadiene rubber,
Usual rubber such as butadiene rubber, ethylene propylene rubber, isoprene rubber, polynorbornene rubber or a thermoplastic rubber such as styrene-butadiene-styrene (SBS) or styrene-butadiene-styrene water additive (SEBS) may be used. It is possible, but is not particularly limited, but these rubbers, particularly solid butadiene rubber / liquid polyisoprene rubber, are mixed at a ratio of about 10/90 to 50/50, and a conductive material is added to this to mix the base layer 2 The base layer 2 having a low hardness and a small compression set can be obtained, and the adhesion between the roll and the charged body such as the photosensitive drum can be improved.

The foamed conductive rubber is not particularly limited, but ethylene propylene rubber mixed with a conductive material, a foam of a copolymer rubber of epichlorohydrin and ethylene oxide, or epichlorohydrin and ethylene oxide is used. It is possible to preferably use a foamed product obtained by mixing the copolymer rubber of (1) with a conductive material.

As the conductive material to be blended with 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 ⁷ Ω · cm. 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 roll and the like, but is usually 1 to 20 mm.

The method of manufacturing the conductive roll of the present invention is
The conductive resin layer 3 formed on the base layer 2 is pressed with a thermoplastic resin.
It is formed by extrusion molding. This place
In this case, as the thermoplastic resin forming the conductive film layer 3,
Any extrudable thermoplastic resin
Well, specifically, Elf Atchem Japan
Trade name of Pebax 4011, MX1723, M
X1074, MX1041, Mitsui DuPont Polychemical
The brand name of Alcline Co., Ltd. and the brand name of Dainichi Seika Co., Ltd.
Zamin, Ube Industries, Ltd. product name PAE1200, PA
E1202 etc. can be illustrated. Among these
Pebax 4011, Arculin, PAE1200, P
AE1202 can be preferably used, but in particular Pebax
4011, Arculin is a conductive film of a conductive roll itself.
1.0 × 10 suitable as a layer⁸~ 1.0 x 10^TenΩ ・ c
It has a volume resistance of m and can be used as it is without adjusting the conductivity.
It is particularly preferable because it can be used
It Resamine, PAE1200, PAE1202
Etc., it is necessary to add a conductive material to adjust its electrical resistance.
However, the adjustment range is 1.0 x 10⁷~ 1.0 x 1
0¹¹Ω · cm, and in this case as a conductive material
Is a general conductive material such as titanium oxide, carbon, conductive tin oxide, etc.
The amount of electrical material can be used.

The formation of the conductive film 3 by the extrusion molding method will be described in detail. For example, a substantially ring-shaped die 4 having an extrusion passage 4a formed on the peripheral wall as shown in FIG.
As shown in FIG. 5, a roll 6 having the base layer 2 formed on the outer periphery of the shaft 1 (not shown) is passed through the hollow portion of the die 4 and the thermoplastic resin 5 is extruded from the extrusion path 4 a of the die 4 into a tube. And then extruded onto the base layer 2 of the roll 6 and moving the roll 6 in one direction to cover the entire outer peripheral surface of the base layer 2 of the roll 6 with the thermoplastic resin 5 to form the conductive film layer 3 Can be formed. In this case, as shown in FIG. 8, the conductive film layer 3 at the roll end is processed obliquely together with the base layer 2 (the left end in the figure), or the conductive film layer 3 is made longer than the base layer 2 and processed obliquely. Can be done (right end in the figure).

Further, in this case, as shown in FIG. 6, after the roll 6 composed of only the base layer 2 formed by molding the rubber or foamed rubber into a thick tube by the molding machine 7 is cross-linked from the molding machine 7 through the heating tank. After covering the conductive film layer 3 through the hollow portion of the die 4 and cutting it to a predetermined length with a cutting machine 8,
As shown in FIG. 7, a conductive roll can also be manufactured by inserting the shaft 1 into the center of the base layer 2 and fixing it with an adhesive if necessary. Further, at this time, as shown by reference numerals 9 and 10 in FIG. 6, after the conductive film layer 3 is formed by coating, soluble fluororesin, various modified nylon such as methoxymethylated nylon, and various modified nylon such as fluorinated urethane. A coating material such as urethane is sprayed from the spray coater 9 onto the surface of the conductive film layer 3 or, as shown in FIG. Further, the contamination prevention layer 10 for preventing the contamination of the charged body such as the photosensitive drum can be formed.

When coating the conductive film layer 3, the base layer 2 may be subjected to an adhesion treatment. As the adhesion treatment, an adhesion treatment by polarizing the surface using a halogen gas or an organic surface treatment agent, etc., or an adhesion treatment by hot melt adhesives, pressure sensitive adhesives, reactive adhesives, one-component adhesives, etc. When using an adhesive, it is preferable to use a conductive adhesive.

After the conductive film layer 3 is coated, if the adhesion to the base layer 2 is poor, the roll may be heat treated to improve the adhesion. In this case, the heat treatment is performed after extruding the conductive film layer 3 or after coating the pollution prevention layer 10, and then the melting point of the thermoplastic resin forming the conductive film layer 3 is 10
It can be performed by heating for 1 minute to 1 hour in the range from a temperature lower by 0 ° C. to the melting point. Such heat treatment removes internal strain when the conductive film layer 3 is covered,
Adhesion with the base layer 3 is improved.

As described above, in the method for manufacturing the conductive roll of the present invention, the conductive film layer is formed by extrusion molding of the thermoplastic resin, so that the thermoplastic resin is extruded directly into a tube on the base layer. The conductive film layer can be formed extremely simply by molding. The manufacturing method of the conductive roll of the present invention is not limited to the manufacturing method shown in FIGS. 3 and 4 above, and the method of forming the base layer and the like can be changed as appropriate, and other configurations are also applicable to the present invention. Various changes can be made within the scope of the gist.

In order to keep the nip width of the conductive roll uniform with the photosensitive drum, as shown in FIG. 2, when the conductive film layer 3 is formed, the film thickness of the conductive film layer 3 is changed. In some cases, the central portion is formed thicker than both end portions, and the outer diameter D ₁ of the roll central portion is formed larger than the outer diameter D _{2 of} both end portions of the roll. In this case, production of the conductive roll of the present invention According to the method, for example, when the conductive film layer 3 is formed by the extrusion molding method shown in FIGS. 5 and 6, the delivery or take-up speed of the roll 6 is gradually reduced from one end of the roll to the central part, and the central part is gradually reduced. The conductive film layer 3 of FIG. 2 can be formed extremely easily by gradually increasing the speed from the first end to the other end.

Here, as shown in FIG. 2, the roll center
Outer diameter D₁Is the outer diameter D at both ends of the roll₂Greater conductivity
Diameter D at the center of the roll₁And b
Outer diameter of both ends₂Difference ΔD (ΔD = D₁− D₂)
Is not particularly limited, roll the photosensitive drum
The degree to which the center of the roll rises when pressed against the base and the base
Designed based on the degree of flexibility of layer 2, the roll and the photosensitive drum
The nip width between them is uniform along the axial direction of the roll
It is something that will be done.

For example, a roll body having a length L is formed on a metal shaft 1 having a length of 245 mm and a diameter of 7 mm.
If a force of 800 g is applied to both ends of the roll to press it against the photosensitive drum, normally, the difference ΔD between the outer diameter D _{1 at the} center of the roll and the outer diameter D _{2 at} both ends of the roll satisfies the following equation. When set to, a substantially uniform nip width can be obtained. 5 × 10 ^-5 <ΔD / L <5 × 10 ^-3

However, if the hardness of the base layer 2 is extremely low or if the shaft 1 flexes extremely greatly, a uniform nip width may not be obtained even if the above formula is satisfied. In such a case, as described above, ΔD may be appropriately changed in consideration of the degree to which the central portion of the roll floats and the degree of flexibility of the base layer 2.

The conductive roll shown in FIG. 2 is formed so that the outer diameter gradually increases from both ends of the roll toward the center, but the present invention is not limited to this and, for example, as illustrated in FIG. , Both ends of which are tapered and have a large diameter part with a uniform diameter in the central part (FIG. A), those in which the central part bulges in an arcuate cross section (FIG. B), A small diameter portion is formed and a large diameter portion having a uniform diameter is formed in the central portion (Fig. C). These conductive rolls illustrated in FIG. 3 can also be easily obtained by appropriately changing the feed rate or the take-up speed of the roll during extrusion molding of the conductive film layer 3 according to the roll shape.

As described above, according to the method of manufacturing a conductive roll of the present invention, the conductive film layer is formed by extrusion molding of a thermoplastic resin, so that the thermoplastic resin is directly formed on the base layer by a tube. Can be formed into a conductive film layer by extrusion into a simple shape, and when the thermoplastic resin is extruded onto the base layer of the roll to form a conductive film layer, the roll-out or take-up speed is changed. By doing so, the thickness of the conductive film layer can be freely controlled, and a conductive roll having an outer diameter at the center of the roll larger than outer diameters at both ends of the roll can be easily and inexpensively manufactured.

The manufacturing method of the conductive roll of the present invention is not limited to the manufacturing method shown in FIGS.
The method of forming the base layer and the like can be appropriately changed, and other configurations can be variously changed within the scope of the gist of the present invention.

[0029]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

[Example 1] A base layer of 3 mm was formed on a steel shaft using a conductive rubber composition having the following formulation.
It was formed thick. In this case, the vulcanization conditions were 160 ° C. × 5 minutes. The hardness of the obtained base layer was Asker C50 °, and the volume resistance thereof was 8 × 10 ² Ω · cm. The electric resistance of the roll (base layer) is, as shown in FIG. 10, a copper plate 12 having a width of 1 cm on the outer peripheral surface of the conductive roll 6.
Is wound around the shaft 1 and 1000 V between the shaft 1 and the copper plate 12.
Is applied, and the resistance value R is obtained from the current value I at this time by the equation R = V / I. Conductive rubber composition formulation cis-1,4-polybutadiene 60% by weight (BR02LL manufactured by Japan Synthetic Rubber Co., Ltd.) Liquid polyisoprene 40% by weight (Kuraray Isoprene LIR30 manufactured by Kuraray Co., Ltd.) Ketjen Black EC 10% by weight Zinc Hua 10% by weight Organic peroxide 0.8% by weight

Next, PAE120 manufactured by Ube Industries, Ltd.
12 parts by weight of Ketjen black and 24 parts by weight of titanium oxide were added and dispersed to 0 and 100 parts by weight to adjust the volume resistance to 1.0 × 10 ⁹ Ω · cm. 5 is extruded onto the above base layer under the following conditions while keeping the moving speed of the roll 6 constant by the method shown in FIG. 5 to form the conductive film layer 3 having the configuration shown in FIG. A conductive roll of was obtained. Extrusion molding conditions Extruder: Plavender φ20 extruder (manufactured by Toyo Seiki) Extrusion conditions: Die 170 ° C Crosshead 170 ° C Screw 170 ° C Hopper 160 ° C Screw rotation speed 60rpm Extrusion rate: 1kg / Hr Drawing speed: 5m / min Extruded film Thickness: 250 μm Dimensions and characteristics Roll length: 240 to 340 mm Roll diameter: φ10 to 20 mm Roll electric resistance: 6 × 10 ⁵ Ω (measured width 1 cm width, H10K1M by the method of FIG. 10)
Ω tester, measured with applied voltage 1000V) Withstand voltage 1.5kV Hardness Asker C 66 °

The obtained conductive roll was set as a charging roll in a laser printer and the temperature was 15 ° C. and the relative humidity was 1
0% RH low temperature and low humidity environment (L / L) and temperature 32.5
When a copying test was performed 20 times in succession in a high temperature and high humidity environment (H / H) of 85 ° C and a relative humidity of 85% RH, L / L,
Both H / H had good image-extracting properties, and the roll was free from scorching.

[Example 2] A conductive rubber sponge having the following formulation was extruded in a hose shape by 2 to 2.5 times and foamed to form a base layer. The vulcanization conditions were 230 ° C. and 3 minutes. Conductive rubber sponge formulation EPDM 100% by weight (T7201EF manufactured by Nippon Synthetic Rubber Co., Ltd.) Oil 70% by weight (PW380 manufactured by Idemitsu Petroleum Co., Ltd.) Polyethylene glycol 1% by weight (PEG4000 manufactured by NOF CORPORATION) Foaming agent 6.5% by weight (Vinyl Hall AC No. 3 or Neocerbon N5000 manufactured by Eiwa Co., Ltd.)

Next, Elf Atchem Japan Co., Ltd.
Made Pebax 4011 (electrical resistance value 1.0 x 10 ⁸ ~
1.0 × 10 ¹⁰ Ω · cm) using the base shown in FIG.
In the method shown in FIG. 6, the moving speed of the roll 6 is continuously changed, and extrusion molding is performed on the base layer under the following conditions to form the conductive film layer 3 having the configuration shown in FIG.
Heat treatment was performed at 0 ° C. × 10 minutes and 150 ° C. × 10 minutes through a hot air oven. Extrusion molding conditions Extruder: Plavender φ20 extruder (manufactured by Toyo Seiki) Extrusion conditions: Die 170 ° C Crosshead 170 ° C Screw 170 ° C Hopper 160 ° C Screw rotation speed 60rpm Extrusion amount: 1kg / Hr Draw speed: 5m / min-10m / Min Extruded film thickness: 250 μm to 500 μm

Then, an N-methoxymethylated nylon layer having a thickness of 10 μm was formed as a pollution prevention layer on the conductive film layer, cut into a predetermined length, and a steel shaft was inserted into the base layer for adhesion. Then, a conductive roll having the following dimensions and characteristics was obtained. Dimensions and characteristics Roll length: 240-340mm Roll diameter: φ10-20mm Roll electrical resistance: 5 × 10 ⁵ Ω (Measurement width 1 cm width, H10K1M by the method of FIG. 10
Ω tester, measured with applied voltage 1000V) Withstand voltage 1.5kV

The base layer and the conductive film layer of the obtained conductive roll were in excellent contact with each other. Then, this conductive roll was set as a charging roll of a laser beam printer, and a copy test was conducted in the same manner as in Example 1, where L /
Both L and H / H had good image-drawing properties, and the roll was free from scorching.

Example 3 A conductive film layer was formed on the same base layer as in Example 1 under the same extrusion molding conditions as in Example 1. At this time, the feeding or take-up speed of the conductive roll was controlled so as to be slow from the end to the center and fast from the center to the end to obtain the conductive roll having the shape shown in FIG. In addition, D ₁ is 14 mm and D ₂ is 13.76.
mm, L = 240, ΔD = D ₁ −D ₂ = 0.24 m
m, ΔD / L = 1 × 10 ⁻³ . The roll characteristics were similar to those of the example.

A force of 800 g was applied to both ends of the shaft 1 of the conductive roll thus obtained, the roll was pressed against the photosensitive drum, and the nip width was measured while rotating both rolls.
A uniform nip width was always obtained along the axial direction of the roll.

[0039]

As described above, according to the method for manufacturing a conductive roll of the present invention, the conductive film layer is formed by extrusion molding using a thermoplastic resin, so that the base layer is directly heated. The conductive film layer can be formed extremely simply by extruding a plastic resin into a tube shape, which requires a plurality of coating steps and drying steps, which requires a lot of labor and cost. The layer forming process can be efficiently performed by a simple operation, and the manufacturing cost of the conductive roll can be effectively reduced.

Further, when the thermoplastic resin is extruded on the base layer of the roll to form the conductive film layer, the speed of feeding or taking the roll is changed so that the thickness of the conductive film layer can be adjusted. It is possible to easily and inexpensively manufacture a conductive roll which is thin at the central part and thick at the central part of the roll and whose outer diameter at the central part of the roll is larger than the outer diameter at both ends of the roll.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing another example of a conductive roll obtained by the manufacturing method of the present invention.

3A to 3C are side views each showing another example of the conductive roll obtained by the manufacturing method of the present invention.

FIG. 4 is a cross-sectional view showing an example of a die for forming a conductive film layer used in the method for producing a conductive roll of the present invention.

FIG. 5 is a schematic partial cross-sectional view showing a method of coating a conductive layer on a base layer using the same die.

FIG. 6 is a schematic partial cross-sectional view showing an example of a method for manufacturing a conductive roll of the present invention.

FIG. 7 is a cross-sectional view showing another example of a conductive roll obtained by the manufacturing method of the present invention.

FIG. 8 is a cross-sectional view showing a processing example of a roll end portion.

FIG. 9 is a cross-sectional view showing an example of a method for forming a pollution prevention layer.

FIG. 10 is a schematic perspective view illustrating a method for measuring electric resistance.

[Explanation of symbols]

 1 Shaft 2 Base Layer 3 Conductive Layer 4 Base 5 Thermoplastic Resin 6 Conductive Roll

Claims (2)

[Claims] 1. A charged body having a shaft, a conductive base layer provided on the outer periphery of the shaft, and a conductive film layer provided on the base layer, the charged body being in contact with the charged body. In the case of producing a conductive roll for applying a potential of a predetermined polarity to, a method for producing a conductive roll, which comprises forming the conductive film layer by extruding a thermoplastic resin onto the base layer. . 2. When the thermoplastic resin is extruded on the base layer of the roll to form the conductive film layer, the speed of feeding or taking out the roll is changed to adjust the thickness of the conductive film layer to both ends of the roll. 2. The method for manufacturing a conductive roll according to claim 1, wherein the conductive roll is formed thin and thick at the center of the roll.