JP2006171643A - Manufacturing method for conductive rubber roller, roller for electrophotographic device, and transfer roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive rubber roller having a uniform aspect ratio of the inside and outside diameters of a tube of a rubber layer and uniform cell distribution and free from irregular hardness and irregular resistance by eliminating irregular foaming and a weld mark, and further radiating a microwave so as to perform heating in a short time and performing vulcanization and foaming in a manufacturing method for a conductive rubber roller such as a transfer roller, an electrifying roller or a developing roller, whose rubber layer is composed of a foamed body. <P>SOLUTION: In the manufacturing method for the conductive rubber roller where a foamed body rubber layer is molded on a conductive core material, a temperature rise heating means depends on the microwave whose intensity is 0.5 to 2.5 kW and hot air, and the head part of an extruder is connected to the inner part on the entrance side of a UHF device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a conductive roller used in an image forming apparatus such as an electrophotographic copying apparatus, a printer, and an electrostatic recording apparatus, and further, an electrophotographic process, an electrostatic recording process, and the like for an image carrier such as a photoreceptor. The present invention relates to a roller for an electrophotographic apparatus such as a transfer roller of a transfer device for transferring a transferable image formed by a toner image formed and supported by the image forming means to a recording medium such as paper or a transfer material.

In many electrophotographic image forming apparatuses such as copying machines and printers, conductive rollers such as a charging roller, a transfer roller, and a developing roller are used. Conventional methods for producing these rubber rollers include vulcanization can vulcanization using high-pressure steam (Patent Document 1), UHF vulcanization using microwave irradiation (Patent Document 2), mold vulcanization using a cylindrical mold (Patent Document 3), Is mentioned. In these methods, for example, in vulcanizing can vulcanization, foam cells are uneven and a large amount of polishing must be performed to bring the desired cells to the surface. It is not suitable for making a large quantity because it requires hanging and mold cleaning. In UHF vulcanization, the setup is good and the cells are uniform, but when the rubber is softened, the tube is crushed and the aspect ratio of the inner and outer diameters of the tube becomes non-uniform. Further, this non-uniformity of the tube causes circumferential hardness and resistance unevenness. Also, in the extrusion process, foaming unevenness and weld marks are generated due to shearing heat when passing through the breaker plate and spider of the extruder head, and hot water and oil are circulated inside the head and heated to eliminate this. Is known as a known technique, however, there is a limit to the temperature for heating, which is insufficient to completely eliminate foaming unevenness and weld marks. However, in the rollers used in future copying machines and printers, the aspect ratio of the foam cell and tube inner and outer diameters is uniform, there is no circumferential hardness, resistance unevenness, foaming unevenness and weld marks, and setup characteristics. There is also a need for a highly productive manufacturing method.
JP 11-114978 A Japanese Patent Laid-Open No. 2002-221859 JP-A-11-201140

  Accordingly, in the present invention, regarding electrophotographic apparatus rollers such as a transfer roller, a charging roller, and a developing roller, foaming unevenness and weld marks due to shearing heat when passing through a breaker plate or spider of an extruder head during extrusion molding, By heating the extruder head part, the unevenness of foam and weld marks are eliminated, and after extrusion, microwaves are irradiated and heated in a short time to vulcanize and foam the rubber layer. The present invention provides a method for producing a conductive rubber roller having uniform aspect ratio of the inner and outer diameters of the tube and cell distribution and having no hardness and uneven resistance, and a roller for an electrophotographic apparatus, in particular, a transfer roller.

  In order to solve the above problems, in the present invention, a method for producing a conductive rubber roller in which a foam rubber layer is inserted onto a conductive core material after extrusion molding of the rubber material of the foam rubber layer and heating foam molding is performed. In the above, the heating foaming means is by a heating device using microwave irradiation and hot air having an intensity of 0.5 to 2.5 kW, and is filled in the head portion of the extruder for extruding the rubber material and in the head. The rubber material is connected to the inside of the inlet side of the heating device so as to be heated to the same temperature as the internal temperature of the heating device, and is further heated and heated by a temperature raising heating means. By increasing the temperature to 100 to 250 ° C. in 5 to 2.5 min, it becomes possible to suppress the roller resistance value and resistance unevenness accompanying rubber deterioration, and the amount of gas generated at that time is 2.0 to 20. 0ml / g Aspect ratio of the tube inner and outer diameters by comprising, and cell distribution becomes uniform. The manufacturing method of the conductive rubber roller characterized by being obtained by the process including such conditions was provided. In the present invention, by using a conductive roller using a tube vulcanized by such a manufacturing method as a roller for an electrophotographic apparatus, the usefulness in this application is increased.

  As shown above, in the method for producing a conductive rubber roller in which a foam rubber layer is inserted on a conductive core after heat foam molding of the rubber material of the foam rubber layer, the heat foaming means comprises: This is due to microwave irradiation and hot air of strength 0.5 to 2.5 kW, and the extruder head portion for extruding the rubber material and the rubber material filled in the head are inside the UHF device (heating device) It is connected to the inside of the entrance side of the UHF device so that it is heated to the same temperature as the temperature. By the manufacturing method of the conductive rubber roller, it passes through the breaker plate and spider of the extruder head at the time of extrusion molding. Eliminate foaming unevenness and weld marks due to shearing heat by using hot air from the UHF device and heating the extruder head. It is possible to provide a method for producing a conductive rubber roller and a roller for an electrophotographic apparatus by foaming so that the aspect ratio of the inner and outer diameters of the tube of the rubber layer and the cell distribution are uniform and hardness and resistance are not uneven. It becomes possible.

  Therefore, the conductive roller using the manufacturing method for the conductive rubber roller is used as a roller for an electrophotographic apparatus, and can be suitably used particularly as a transfer roller.

  The present invention relates to a method for producing a conductive rubber roller in which a foam rubber layer is inserted on a conductive core material after heat foam molding of the rubber material of the foam rubber layer, wherein the heat foaming means has a strength of 0. 5 to 2.5 kW of microwave irradiation and hot air, and the rubber material filled in the head portion of the extruder for extruding the rubber material and the rubber material filled in the UHF (atmosphere temperature in the heating device) It is an electroconductive rubber roller characterized by being connected to the inside of the entrance side of a UHF device so that it may be heated to the same temperature.

  Hereinafter, the present invention will be described in detail.

(When applied to electrophotographic equipment)
FIG. 2 shows an example in which the conductive roller according to the present invention is used in an image forming apparatus. The image forming apparatus shown in the figure is an electrophotographic laser printer using a process cartridge, and the figure is a longitudinal sectional view showing a schematic configuration thereof. Further, the image forming apparatus shown in the figure is equipped with a transfer device having a transfer roller.

  The image forming apparatus shown in FIG. 1 includes a drum-type electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 1 as an image carrier. In the photosensitive drum 1, a photosensitive layer made of an organic photoconductor (OPC) is provided on the outer peripheral surface of a grounded cylindrical aluminum substrate. The photosensitive drum 1 is driven to rotate at a predetermined process speed (circumferential speed), for example, 50 mm / sec, in the direction of arrow R1 by a driving means (not shown).

  The surface of the photosensitive drum 1 is uniformly charged by a charging roller 2 as a contact charging member. The charging roller 2 is disposed in contact with the surface of the photosensitive drum 1 and is driven to rotate in the direction of arrow R2 as the photosensitive drum 1 rotates in the direction of arrow R1. An oscillating voltage (AC voltage VAC + DC voltage VDC) is applied to the charging roller 2 by a charging bias application power source (high voltage power source), whereby the surface of the photosensitive drum 1 is uniformly charged to −600 V (dark portion potential Vd). Is done. The surface of the photosensitive drum 1 after charging is subjected to scanning exposure by laser light 3 output from a laser scanner and reflected by a mirror, that is, laser light modulated in accordance with a time-series electric digital image signal of target image information. receive. As a result, an electrostatic latent image corresponding to the target image information (bright part Vl = −150 V) is formed on the surface of the photosensitive drum 1.

  The electrostatic latent image is reversely developed as a toner image with negatively charged toner attached thereto by a developing bias applied to the developing sleeve of the developing device 4.

  On the other hand, a transfer material 7 such as paper fed from a paper supply unit (not shown) is guided by a transfer guide, and is transferred to a transfer unit (transfer nip unit) T between the photosensitive drum 1 and the transfer roller 6. The toner image is supplied in synchronism with the toner image on the photosensitive drum 1. The toner image on the photosensitive drum 1 is transferred to the surface of the transfer material 7 supplied to the transfer portion T by a transfer bias applied to the transfer roller 6 by a transfer bias application power source. At this time, the toner (residual toner) that is not transferred to the transfer material 7 and remains on the surface of the photosensitive drum 1 is removed by the cleaning device 9.

  The transfer material 7 that has passed through the transfer portion T is separated from the photosensitive drum 1 and introduced into the fixing device 10, where the toner image is subjected to fixing processing, and an image forming apparatus main body (not shown) as an image formed product (print). It is discharged outside.

(Method for producing conductive roller)
The rubber material of the foam rubber layer in the conductive roller is composed of a rubber composition containing epichlorohydrin rubber, acrylonitrile butadiene rubber, or a mixture thereof, and further containing azodicarbonamide. In the method for producing a conductive rubber roller, which is inserted through a conductive core material after heat foaming of the rubber material of the foam rubber layer, the heat foaming means comprises microwave irradiation with a strength of 0.5 to 2.5 kW, UHF is heated by the hot air, and the head portion of the extruder for extruding the rubber material and the rubber material filled in the head are heated to the same temperature as the internal temperature of the UHF (heating device). Manufactured with an extrusion vulcanizer connected to the inside of the inlet side of the device.

  FIG. 3 shows a production apparatus by continuous vulcanization using a microwave of a conductive roller. The extrusion vulcanization apparatus used in this experiment has a total length of 13 m, 11 is an extruder, and 12 is a microwave vulcanization apparatus (heating). Equipment: Equipment for heating and foaming raw materials with microwaves and hot air (UHF), 13 is a hot air vulcanizer (HAV), 14 is a take-up machine, and 15 is a regular cutting machine. It is preferable that the temperature of the hot air in a heating apparatus is 150-300 degreeC, and it is more preferable that it is 150-250 degreeC.

  Next, it is conveyed to a hot air vulcanizer (HAV) 13 by a roller (belt conveyor) coated with Teflon resin.

  After kneading using a closed kneader such as a Banbury mixer or a kneader, the rubber composition molded into a ribbon shape with an open roll and a ribbon molding dispenser is put into the extruder 11. The microwave vulcanizer (UHF) 12 conveys a rubber tube extruded from the extruder 11 with a mesh belt coated with Teflon or a roller coated with Teflon resin, and a hot air vulcanizer (HAV). Reference numeral 13 denotes a roller covered with a Teflon resin. The microwave vulcanizer (UHF) 12 and the hot air vulcanizer (HAV) 13 are connected by a roller coated with Teflon resin.

  The lengths of the devices 12, 13, and 14 are as shown in the figure, and in this embodiment, the lengths are 4m, 6m, and 1m, respectively. The space between the microwave vulcanizer (UHF) 12 and the hot air vulcanizer (HAV) 13 and between the hot air vulcanizer (HAV) 13 and the take-up machine 14 are set to be 0.1 to 1.0 m. .

  As shown in FIG. 4, the head portion 17 of the extruder 11 is inserted into the microwave vulcanizer (UHF) 12, and the same temperature as that in the microwave vulcanizer (UHF) 12 through the hot air blowing port 18. The hot air is blown to heat the head portion 17. Note that a microwave radio wave stopper 16 is provided in the head portion so that the microwave does not enter the head portion.

  In the manufacturing apparatus by continuous vulcanization using the microwave, the rubber tube formed and extruded into a tube shape from the extruder 11 is placed in the microwave vulcanizer (UHF) 12 immediately after being extruded from the extruder 11. Is heated so that the gas generation amount becomes 2.0 to 20.0 ml / g when heated to 100 to 250 ° C. for 1.5 to 2.5 min, followed by vulcanization and foaming. Then, it is conveyed to a hot air vulcanizer (HAV) 13 to complete vulcanization.

  Immediately after being discharged from the winder 14 after vulcanization and foaming, it was cut into a desired size by a regular cutting machine 15 to produce a tubular conductive rubber molded product. Next, a conductive core material having a diameter of 4 to 10 mm coated with a hot melt adhesive or a vulcanized adhesive in a desired region is press-fitted into the inner diameter portion of the tube-shaped conductive rubber molding to obtain a roller-shaped molded body. It was. This molded body is set in a polishing machine (not shown) to which a grinding wheel GC80 is attached, and is polished so that the outer diameter is 17 mm at a rotation speed of 2000 RPM and a feed speed of 500 m / min. It was created.

  The conductive roller (FIG. 1) demonstrating this invention was produced as follows as an example.

  [Conductive roller]: The rubber composition contains acrylonitrile butadiene rubber, epichlorohydrin rubber, or a mixture thereof as a main rubber component, and a predetermined amount thereof is mixed. Also, conductive materials such as carbon black, fillers such as calcium carbonate, other auxiliaries and vulcanizing agents such as sulfur, organic peroxides, triazines, polyamines, thiurams, thiazoles, guanidines, sulfenamides , Dithiocarbamate, thiourea, or a mixture of several vulcanization accelerators and azodicarbonamide foaming agents.

  After extruding the rubber composition using an extruder (Fig. 3), microwave irradiation and hot air heating (hot air temperature 200 ° C) in UHF furnace so that the temperature rises 100-250 ° C in 1.5-2.5 min. And if necessary, heat in a hot air oven for 4 to 10 minutes at 150 to 300 ° C. to produce a tube-shaped conductive rubber molding, and then hot melt adhesive or vulcanization A conductive core material having a diameter of 4 to 10 mm coated with an adhesive in a desired region was press-fitted into the inner diameter portion of the tube-shaped conductive rubber molding to obtain a roller-shaped molded body (inner diameter 5.0 mm, outer diameter 16.0 mm). This molded body is set in a polishing machine (not shown) to which a grinding wheel GC80 is attached, and is polished so that the outer diameter is 17 mm at a rotation speed of 2000 RPM and a feed speed of 500 m / min. It was created.

In addition, the material used by each Example and the comparative example is as follows.
Acrylonitrile butadiene rubber [trade name: DN401, manufactured by Nippon Zeon Co., Ltd.]
Epichlorohydrin rubber [Product name: Zeklon 3106, manufactured by Nippon Zeon Co., Ltd.]
Azodicarbonamide [Brand name: VINYHALL AC, manufactured by Eiwa Kasei Kogyo Co., Ltd.]
(Confirmation method for uneven foaming)
The foaming unevenness was visually confirmed after the outer diameter was polished. Those having streaky foaming unevenness were rated as x, and those having no streaky foaming were marked as ◯.

(How to check the weld mark)
The weld mark was immediately after extrusion, and the cross section of the extruded product was observed to confirm the presence or absence of rubber shrinkage (weld mark) at the same position as the spider. The case where the shrinkage was seen was marked with ×, the lightness was marked with Δ, and the thinness was marked with ○.

(Measurement method of rubber temperature during microwave irradiation)
Using a fluorescence thermometer (Anritsu Fluorescent fiber optic thermometer FL-2000), insert the detection unit of the fluorescence thermometer into the unvulcanized rubber tube extruded from the extruder and place it in the microwave vulcanizer (UHF). Convey with unvulcanized rubber tube and measure temperature at that time.

(Measurement method of gas generation amount)
Using a gas tracer (Yewa Kasei Kogyo Gas Tracer 250), 5.0 g of unvulcanized rubber (rubber composition before heating and foaming) to be used is placed in a test tube, and the test tube is immersed in an oil bath. The temperature of the oil bath is raised from around 30 ° C. to around 300 ° C. in 30 minutes, and the amount of gas generated is read.

(Aspect ratio measurement method for tube inner and outer diameters)
The tube was cut at an arbitrary location, and the cross section of the tube was measured with a projector (Nikon Profile Projector V-12B) to measure the maximum (a) and minimum (b) of each inner and outer diameter, and the ratio was measured. At this time, b / a is preferably closer to 1.

(Measurement method of hardness unevenness)
Using a hardness meter (Asker C type, 4.9N load), arbitrary positions of the tube made into a conductive roller were measured at 90 ° positions in the circumferential direction, and the difference between the maximum value and the minimum value was expressed. The difference is preferably zero.

(Measurement method for uneven electrical resistance of rollers)
Roller resistance is made of aluminum with an outer diameter of 30 mm so that a load of 4.9 N on one side is applied to both sides of the shaft of the conductive roller after standing for 48 hours in an N / N (23 ° C. × 55% RH) environment. The pressure was measured by applying a voltage of 2 kV between the shaft body and the aluminum drum in a state in which the drum was pressed and rotated. The difference between the maximum and minimum resistance values at this time was represented by a digit (measured value represented by a logarithmic function). The difference is preferably less than 1.2 digits.

(Confirmation method of cell diameter distribution)
Cut the tube at an arbitrary location, check the cross section with a video microscope (Keyence Digital Microscope VH-8000), and the cell diameter on the outer diameter side (the diameter of the cell located 7.0 mm from the center). The difference in the cell diameter on the inner diameter side (the diameter of the cell located at a position 3.5 mm from the center) was confirmed. At this time, it is preferable that there is no difference between the cell diameter on the outer diameter side and the cell diameter on the inner diameter side. Specific examples are described below.

(Examples 1-5)
The rubber material used in the present invention comprises epichlorohydrin rubber, acrylonitrile butadiene rubber, or a mixture thereof, and further comprises a rubber composition containing azodicarbonamide. In this embodiment, an extruder having a head part on the outlet side is used, and this head part is connected to the inlet side opening of the UHF device so that it can be heated to the same temperature as the internal temperature of the UHF. After extruding with an extruder, a foam rubber layer is formed on the rubber composition by microwave irradiation with a strength of 0.5 to 2.5 kW and heating with hot air at UHF. A plurality of various cases in which the amount of gas generated when the temperature was raised by 100 to 250 ° C. for 2.5 minutes were 2.0 to 20.0 ml / g were set as examples. Moreover, the foam rubber layer was inserted on the conductive core material to obtain a conductive rubber roller. From this result, there is no foaming unevenness or weld mark due to shear heat when passing through the breaker plate or spider of the extruder head, the aspect ratio of the inner and outer diameters of the tube is close to 1, and the hardness unevenness in the circumferential direction is also small. It can be seen that the non-uniformity of resistance is 1.2 digits or less. The results are listed in Table 1.

(Comparative example)
A plurality of cases that did not meet the definition of the present invention were set as comparative examples. As a comparative example, the head part of the extruder is set to the same conditions as in the example except that a space is provided between the head part outlet of the extruder and UHF so as not to be affected by the hot air of UHF. Various examples were given in which the gas generation amount was 2.0 to 20.0 ml / g when the rubber composition was irradiated with microwaves and heated to 100 to 250 ° C. for 1.5 to 2.5 minutes. In these cases, the aspect ratio of the inner and outer diameters of the tube, the hardness unevenness in the circumferential direction, and the resistance unevenness in the circumferential direction are improved in the same manner as in the examples, but the foaming unevenness due to shear heat when passing through the breaker plate or spider of the extruder head part Weld marks are worse than in the examples. The results are listed in Table 2.

1 is an overall cross-sectional view of a transfer roller according to the present invention. FIG. 1 is an overall cross-sectional view of an image forming apparatus according to the present invention. Overall sectional view of a vulcanization molding apparatus according to the present invention Connection of extruder and microwave vulcanizer (UHF) according to the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging apparatus 3 Exposure means 4 Developing apparatus 5 Toner 6 Transfer roller 7 Recording medium 8 Cleaning blade 9 Waste toner container 10 Fixing apparatus 11 Extruder 12 Microwave vulcanizing apparatus (UHF)
13 Hot air vulcanizer (HAV)
14 Take-up machine 15 Standard cutting machine 16 Microwave wave stopper 17 Extruder head 18 Hot air blowing port 61 Core metal 62 Elastic layer

Claims (8)

  In the method for producing a conductive rubber roller in which a foam rubber layer is extruded through a rubber material of the foam rubber layer, and heated and foamed and then inserted onto a conductive core material, the heating foam means has a strength of 0.5. It is based on a heating device using a microwave of 2.5 kW and hot air, and the head portion of the extruder for extruding the rubber material and the rubber material filled in the head are the internal temperature of the heating device. A method for producing a conductive rubber roller, characterized in that the conductive rubber roller is connected to the inside of the inlet side of the heating device so as to be heated to the same temperature.   The method for producing a conductive rubber roller according to claim 1, wherein the means for heating the head portion of the extruder and the rubber material to the same temperature as the internal temperature of the heating device is by hot air of the heating device. .   The amount of gas generated during heating and foaming by the heating device is raised to 100 to 250 ° C. in 1.5 to 2.5 min, and becomes 2.0 to 20.0 ml / g. The method for producing a conductive rubber roller according to claim 1, wherein the conductive rubber roller is obtained by a condition step.   The method for producing a conductive rubber roller according to claim 2 or 3, wherein the hot air of the heating device uses an electric furnace or a gas furnace as a heat source.   5. The method according to claim 1, wherein after the step of irradiating and heating the rubber material with microwaves of the heating device, the rubber material is further heated in a hot stove step at 4 to 10 min and 150 to 300 ° C. 5. The manufacturing method of the electroconductive rubber roller of description.   The method for manufacturing a conductive rubber roller according to claim 5, wherein the hot stove step is performed using a gas furnace as a heat source.   A roller for an electrophotographic apparatus in which a foam rubber layer is formed on a conductive core material, wherein the rubber material of the foam rubber layer includes epichlorohydrin rubber, acrylonitrile butadiene rubber, or a mixture thereof. A roller for an electrophotographic apparatus, comprising a rubber composition containing azodicarbonamide and formed by the method for producing a conductive rubber roller according to any one of claims 1 to 6.   The roller for an electrophotographic apparatus according to claim 7, wherein the roller for the electrophotographic apparatus is a transfer roller used for a transfer apparatus portion of the electrophotographic apparatus.

Images