JP2009223214A - Charging device, image forming unit, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device including an elastic layer having stable electric conductivity by preventing the generation of bloom or bleed even after long-term storage, and to provide an image forming unit including the same, and an image forming apparatus including the image unit. <P>SOLUTION: The charging device includes a conductive metal body, the elastic layer formed on the metal body, and a power supply part connected to the metal body and applying a voltage to the metal body. At least the outermost layer of the elastic layer mainly includes a chloroprene rubber, and the elastic layer has a surface treated with treatment liquid containing isocyanate. The image forming unit includes the charging device, and the image forming apparatus includes the image unit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charging device, an image forming unit, and an image forming apparatus.

  In an electrophotographic image forming apparatus such as a printer, a copying machine, a facsimile machine, or a multifunction machine, a corona discharge charging device is often used as a charging device for charging an image carrier on which an electrostatic latent image is formed. I came. The corona discharge method is a charging method that induces corona discharge by applying a high voltage to a thin wire such as tungsten to charge the image carrier.

  However, the corona discharge charging device has a problem that a high voltage power source for applying a high voltage is required and high concentration ozone is generated by corona discharge.

  Therefore, in recent years, instead of the above-described corona discharge type charging device, a roller type charging device that charges the image carrier by bringing a charged roller to which a voltage is applied into contact with or close to the image carrier is preferred. It is used.

  In the roller charging device, the elastic layer of the charging roller for charging the image carrier is required to have various properties such as predetermined conductivity and non-contamination to the image carrier. As an elastic layer having such properties, ion conductive epichlorohydrin rubber has been widely used so far (for example, Patent Document 1).

JP-A-10-39582

  However, epichlorohydrin rubber often contains a crosslinking agent for dechlorination and a vulcanization accelerator for assisting vulcanization for the purpose of preventing contamination of the image carrier. For example, when a charging roller using an epichlorohydrin rubber compounded with a metal oxide such as zinc oxide as a vulcanization accelerator is stored for a long period of time, bloom or bleed occurs in the elastic layer, and the metal on the elastic layer surface Oxide may come out. As a result, the metal oxide adheres to the surface of the elastic layer, resulting in a problem that uniform charging of the image carrier is hindered.

  In view of the above circumstances, an object of the present invention is to provide a charging device provided with an elastic layer that prevents the occurrence of bloom or bleed and has stable conductive properties even when stored for a long period of time. It is another object of the present invention to provide an image forming unit including the charging device and an image forming apparatus including the image unit.

  As a result of earnest research, the inventor of the present invention has a layer containing chloroprene rubber as a main component in at least the outermost layer of the elastic layer, and the surface of the elastic layer is treated with a treatment liquid containing isocyanate. It came to obtain the knowledge that can be solved. That is, a charging device according to the present invention includes a conductive metal body, an elastic layer formed on the metal body, and a power supply unit that is connected to the metal body and applies a voltage to the metal body. At least the outermost layer is a layer mainly composed of chloroprene rubber, and the elastic layer has a surface treated with a treatment liquid containing isocyanate.

  Chloroprene rubber is a general-purpose rubber that balances mechanical strength, weather resistance, chemical resistance, heat resistance, cold resistance, and oil resistance. By treating the surface of the elastic layer having at least the outermost layer mainly composed of chloroprene rubber having such characteristics with a treatment liquid containing isocyanate, the surface can be cured to obtain better durability. it can. Therefore, even when stored for a long time, occurrence of bloom or bleed can be prevented.

  An image forming unit according to the present invention is an image forming unit including an image carrier on which an electrostatic latent image is formed, and a charging member that is provided in contact with the image carrier and charges the image carrier. The charging member includes a conductive metal body, a surface formed with the treatment liquid containing isocyanate, and at least the outermost layer including an elastic layer mainly composed of chloroprene rubber. It is characterized by that.

  The image forming unit of the present invention includes a charging member provided in contact with an image carrier on which an electrostatic latent image is formed. The charging member includes a conductive metal body, a surface formed with a processing liquid containing isocyanate, and an outermost layer including an elastic layer mainly composed of chloroprene rubber. Since the elastic layer has increased durability, the surface roughness due to the occurrence of bloom or bleed does not increase even when stored for a long time. Therefore, the image carrier can be charged stably and uniformly.

  According to the present invention, it is possible to provide a charging device including an elastic layer that prevents the occurrence of bloom or bleed even when stored for a long period of time and has stable conductive properties. In addition, an image forming unit including the charging device and an image forming apparatus including the image unit can be provided.

  The present invention will be described below with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.

[First embodiment]
FIG. 1 is a schematic configuration diagram illustrating a configuration example of a printer 100 as an image forming apparatus according to a first embodiment of the present invention. In the description of this embodiment, a charging device including a charging roller as a charging member will be described as an example. In this description, first, the overall configuration of the printer 100 will be described, and then the image forming unit including the charging roller according to the present embodiment and the charging roller according to the present embodiment will be described in this order.

First, the printer 100 will be described.
The printer 100 includes an image forming unit 20 that forms a toner image, an exposure device 21 that forms an electrostatic latent image on a photosensitive drum 1 to be described later by emitting light based on input print data, and the image forming unit 20. A transfer device 22 that transfers the formed toner image onto the paper 24, a fixing device 23 that fixes the toner image transferred onto the paper 24, a paper 24 on which an image is formed, and a paper feed that feeds the paper 24 A roller 25, transport guides 26a and 26b for guiding the paper 24, a transport roller 27 for transporting the paper 24, a discharge roller 28 for discharging the paper 24 transported from the fixing device 23, and a discharge roller 28. And a stacker 29 on which the sheets 24 are stacked.

  The image forming unit 20 is provided on the paper transport path and forms a toner image based on the electrostatic latent image formed by the exposure device 21. The configuration of the image forming unit 20 will be described in detail later.

  The exposure device 21 includes, for example, a light emitting element such as an LED (Light Emitting Diode) and a lens array, and the irradiation light output from the light emitting element forms an image on the surface of the photosensitive drum 1 as an image carrier to be described later. Arranged. The exposure device 21 forms an electrostatic latent image on the outer peripheral surface of the photosensitive drum 1 by emitting light based on the input print data.

  The transfer device 22 includes an endless transport belt (not shown) that electrostatically attracts and transports the paper 24, and a drive roller (not shown) that drives the transport belt by rotating with power transmitted from a drive system (not shown). And a transfer roller disposed so as to be in pressure contact with the photosensitive drum 1 via a conveyor belt. A high voltage is applied to the transfer roller from a power supply system (not shown), and the toner image formed by the image forming unit 20 is transferred to the paper 24.

  The fixing device 23 includes a heat roller 23a that can rotate around a central axis, and a pressure roller 23b that is provided in pressure contact with the heat roller. The heat roller 23a has a metal cored bar such as aluminum or iron in which a halogen lamp as a heating member is incorporated, and an elastic body such as silicon rubber is provided on the surface thereof. The surface of the elastic body is covered with a coating layer or a tube having the same function for ensuring separation from the toner image transferred to the paper 24. The pressure roller 23b is provided so as to be in contact with the surface of the heat roller with a constant pressure by a tension spring (not shown). The fixing device 23 applies heat and pressure to the sheet 24 by nipping and conveying the sheet 24 in a nip formed by the heat roller 23a and the pressure roller 23b.

  The paper 24 is, for example, a sheet-like recording paper on which an image is formed.

  The paper feed roller 25 has at least a pair of rollers, and is rotated by power transmitted from a drive system (not shown) to separate the paper 24 one by one and transport the paper 24 toward the image forming unit 20. To do.

  The conveyance guides 26a and 26b are guide members that guide the paper 24 along the conveyance path. The conveyance guide 26 a guides the paper 24 conveyed from the paper supply roller 25 to the image forming unit 20. Further, the conveyance guide 26 b guides the paper 24 conveyed from the fixing device 23 to the discharge roller 28.

  The conveyance roller 27 includes a pair of rollers, and is provided at the end of the conveyance guide 26a in the sheet conveyance direction. The conveyance roller 27 conveys the sheet 24 guided along the conveyance guide 26 a to the image forming unit 20.

  The discharge roller 28 includes at least a pair of rollers, and is provided at the end of the conveyance guide 26b in the sheet conveyance direction. The discharge roller 28 discharges the sheet 24 guided along the conveyance guide 26 b to the stacker 29.

  The stacker 29 is formed using one surface of the outer surface of the casing of the printer 100. The stacker 29 stacks the sheets 24 discharged from the discharge roller 28.

  In FIG. 1, the printer 100 equipped with one image forming unit 20 having a single color developer is shown, but the present invention is not limited to this. For example, it is possible to print a color image by continuously mounting a plurality of image forming units 20 provided with developers of four different colors (for example, cyan, magenta, yellow, and black) on the paper conveyance path. .

  Next, the configuration of the image forming unit 20 will be described with reference to FIG. FIG. 2 is a main part configuration diagram illustrating a schematic configuration of the image forming unit 20.

  The image forming unit 20 includes a photosensitive drum 1 as an image carrier on which an electrostatic latent image is formed on an outer peripheral surface by an exposure device 21, a charging roller 2 that uniformly charges the outer peripheral surface of the photosensitive drum 1, and a photosensitive drum. 1 includes a developing device 4 that supplies a developer to the electrostatic latent image formed in 1 to form a toner image, and a cleaning device 8 that scrapes off the developer 5 remaining on the transfer belt and dirt adhering to the photosensitive drum 1. .

  The photosensitive drum 1 includes a photosensitive layer portion in which a photosensitive layer is coated on a conductive support processed into a cylindrical shape. The photosensitive layer portion has a laminated structure having a blocking layer, a charge generation layer, and a charge transport layer in order from the surface of the conductive support. The charge transport layer on the outermost surface contains, for example, a polycarbonate resin as a main component, a charge transport compound, an antioxidant, and the like. At the time of printing, the photosensitive drum 1 rotates in the arrow direction (clockwise) around the central axis by the power transmitted by a drive system (not shown).

  The charging roller 2 has a conductive metal core made of, for example, a metal shaft, and has a conductive elastic layer on the outer peripheral surface except for both ends of the metal core. For the elastic layer, a rubber material is preferably used so as to obtain an appropriate nip with the photosensitive drum 1 in order to obtain an appropriate discharge with the photosensitive drum 1. The hardness of the rubber material in this case is preferably 30 to 80 with a type A durometer (JIS K 6253 A). In general, when the resistance of the charging roller 2 is too large, there may be an image defect due to uneven charging or defective charging on the outer peripheral surface of the photosensitive drum 1. On the other hand, if the resistance is too small, an image defect may occur because a leak current flows through a scratch on the outer peripheral surface of the photosensitive drum 1. Therefore, an appropriate resistance region exists in the conductive characteristics of the charging roller 2. The charging roller 2 having appropriate conductive characteristics is provided in contact with the outer peripheral surface of the photosensitive drum 1. During printing, the charging roller 2 is rotated in the direction of the arrow (counterclockwise) following the rotation of the photosensitive drum 1. A voltage is applied to the core of the charging roller 2 to charge the photosensitive drum 1 while rotating in the direction of the arrow. The charging device 3 including the charging roller 2 and the power supply system will be described in detail later.

  The developing device 4 carries the developer 5 that visualizes the electrostatic latent image by adhering to the electrostatic latent image, the developer box 6 that accommodates the developer 5, and the developer 5, and develops it on the photosensitive drum 1. And a developing roller 7 for supplying the agent.

  The developer 5 is composed of toner and aggregates. The toner is obtained by adding an external additive such as an inorganic fine powder to toner base particles containing at least a binder resin. The aggregate is formed by agglomerating the external additive into a lump.

  The developer box 6 is a hollow structure housing the developer.

  The developing roller 7 includes a metal shaft and a semiconductive urethane layer, and is provided in contact with the outer peripheral surface of the photosensitive drum 1. During printing, the developing roller 7 is rotated in the direction of the arrow (counterclockwise) following the rotation of the photosensitive drum 1. A voltage is applied to the metal shaft of the developing roller 7 to attract the developer 5 supplied from a supply roller (not shown), and the developer 5 is supplied to the photosensitive drum 1 by being rotated and conveyed in the direction of the arrow.

  The developing device 4 having such a configuration can be detachably mounted at a predetermined position of the image forming unit 20.

  The cleaning device 8 includes a cleaning blade 9 that scrapes off the developer 5 remaining on the transfer belt and dirt adhering to the photosensitive drum 1, and a waste developer tank 10 that collects the developer 5 scraped off by the cleaning blade 9. .

  The cleaning blade 9 can be made of, for example, urethane rubber. The cleaning blade 9 is disposed in parallel along the central axis direction of the photosensitive drum 1, and its root portion is attached to and fixed to a rigid support base so that the tip end of the cleaning blade 9 is in contact with the outer peripheral surface of the photosensitive drum 1. .

  The waste developer tank 10 is disposed in a lower part of the cleaning blade 9 and collects the developer 5 scraped off by the cleaning blade 9.

  A printing operation of the printer 100 equipped with the image forming unit 20 having the above-described configuration will be described.

  First, when print data is input to the printer 100, a print control unit (not shown) supplies a print start instruction to a drive system (not shown). The drive system supplied with the print instruction transmits power to the paper feed roller 25 and the transport roller 27. The paper feed roller 25 and the transport roller 27 to which power is transmitted start to rotate. The paper feed roller 25 separates the paper 24 one by one and conveys the paper 24 toward the image forming unit 20.

  The sheet 24 guided along the conveyance guide 26 a is conveyed to the image forming unit 20 by the rotation of the conveyance roller 27.

  At this time, power is transmitted to the photosensitive drum 1 in the image forming unit 20 by a drive system (not shown), and the photosensitive drum 1 starts to rotate at a constant speed in the direction of the arrow in FIG. The charging roller 2 provided in contact with the outer peripheral surface of the photosensitive drum 1 starts to rotate at a constant speed in the direction of the arrow in FIG.

  A DC voltage of about −1000 V is applied to the charging roller 2, and the charging roller 2 charges the outer peripheral surface of the photosensitive drum 1 while being driven to rotate. Due to the voltage supplied from the charging roller 2, the outer peripheral surface of the photosensitive drum 1 has a surface potential of −500V. Next, the exposure device 21 provided facing the photosensitive drum 1 irradiates the outer peripheral surface of the photosensitive drum 1 with light based on the image signal of the received print data, and attenuates the potential of the light irradiation portion to statically. An electrostatic latent image is formed. At this time, the surface potential of the exposed portion is 0 to −100V.

  Next, the developing roller 7 in the developing device 4 attaches the developer 5 supplied from a supply roller (not shown) to the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1 to invert the electrostatic latent image. Develop to form a toner image.

  The transfer device 22 to which a high voltage is applied from a power supply system (not shown) transfers the toner image formed on the outer peripheral surface of the photosensitive drum 1 to the paper 24 in accordance with the arrival timing of the paper 24 to the photosensitive drum 1. Transcript. The sheet 24 onto which the toner image has been transferred is conveyed to the fixing device 23. The heat roller 23 a and the pressure roller 23 b constituting the fixing device 23 apply heat and pressure to the paper 24 by nipping and conveying the paper 24. The toner image transferred onto the paper 24 is fixed by heat and pressure applied from the fixing device 23.

  The sheet 24 on which the toner image is fixed is guided along the conveyance guide 26 b and conveyed to the discharge roller 28. The discharge roller 28 is rotated by power transmitted from a drive system (not shown), and discharges the paper 24 to the stacker 29.

  The developer remaining on the outer peripheral surface of the photosensitive drum 1 without being transferred to the paper 24, paper dust attached to the photosensitive drum 1 during the transfer operation, and the like are removed by the cleaning device 8. The outer peripheral surface of the cleaned photosensitive drum 1 is charged again by the charging roller 2, and the next image formation is started. Thereafter, this process is repeatedly executed.

  Next, the charging device 3 according to the first embodiment of the present invention will be described in more detail.

  As shown in FIG. 3, the charging device 3 of this embodiment includes a charging roller 2 that uniformly charges the outer peripheral surface of the photosensitive drum 1, and a charging device power supply 14 a that applies a DC voltage to the charging roller 2.

  As described above, the charging roller 2 is provided so as to face and contact the photosensitive drum 1. The charging roller 2 is driven by the rotation of the photosensitive drum 1 and rotates at a constant speed in the direction of the arrow (counterclockwise) in FIG. 3 to charge the outer peripheral surface of the photosensitive drum 1.

  As shown in FIGS. 4 and 5, such a charging roller 2 has a conductive elastic layer 12 on the outer peripheral surface of a core metal 11 to which a voltage is applied from a charging device power supply 14 a, and the conductive elastic layer 12. The surface treatment layer 13 is uniformly provided on the surface.

The conductive elastic layer 12 is made of a rubber material containing chloroprene rubber as a main component and blended with other rubber. Further, the conductive elastic layer 12 contains a conductive agent for imparting conductivity, and the volume resistance is 10 so as to show an appropriate resistance value when the conductive elastic layer 12 is molded into a roller shape. It is set to ¹² Ω · cm or less.

  Although it does not specifically limit as a electrically conductive agent, It is preferable to use electronic electrically conductive agents, such as carbon black. Moreover, it is good also as the electroconductive elastic layer 12 which shows the electroconductive property of a hybrid of electronic conduction and ionic conduction by adding an ionic conductive agent in addition to an electronic conductive agent.

  When kneading to uniformly disperse the added conductive agent, it is preferable to knead in a state where a necessary addition amount of a part of the vulcanizing agent is added. After increasing the dispersion of the conductive agent, re-kneading and adding the remaining vulcanizing agent can suppress variation in resistance value.

Next, the surface treatment of the conductive elastic layer 12 described above will be described.
The surface treatment layer 13 is formed by allowing the conductive elastic layer 12 molded into a roller shape to penetrate into a surface treatment solution containing an isocyanate component and curing it. The isocyanate component in the surface treatment liquid penetrates from the surface of the conductive elastic layer 12 and cures to form the surface treatment layer 13, but there is no clear boundary between the surface treatment layer 13 and the conductive elastic layer 12. . By curing the surface of the conductive elastic layer 12, even if the conductive elastic layer 12 comes into contact with the outer peripheral surface of the photosensitive drum 1, the photosensitive drum 1 is prevented from being contaminated, and the developer and its external additives And the like can be secured.

  The surface treatment liquid contains an isocyanate component as described above. This surface treatment liquid is obtained by dissolving an isocyanate compound in an organic solvent. Further, for example, any one of a polyester polyol, a polycarbonate polyol, a silicon diol, an acrylic fluorine polymer, and an acrylic silicone polymer is used. It may be added. In addition, a conductive agent such as carbon black can be further added to the surface treatment liquid.

  Examples of the isocyanate compound described above include toluene diisocyanate (TDI), methylene diisocyanate (MDI), xylene diisocyanate (XDI), tphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and multiples thereof. Or modified products thereof. The molecular weight Mw of this isocyanate compound is preferably from 600 to 12000, more preferably from 700 to 3000.

  The organic solvent is not particularly limited, but an organic solvent having high affinity with an isocyanate compound, volatile, and available at a relatively low cost is preferable. Specific examples include ethyl acetate, butyl acetate, and xylene.

  The charging roller 2 of this embodiment is molded in the order of rubber kneading, extrusion into a roller shape, vulcanization, press-fitting of the roller into a metal core, secondary vulcanization, polishing, and surface treatment. The method for molding the charging roller 2 of the present embodiment is not limited to this.

  In the examples described below, the conductive elastic layer 12 was produced by using chloropyrene rubber as a main component and changing the blending ratio of additives to be blended. Further, the surface treatment of the conductive elastic layer 12 was performed using a surface treatment liquid having a composition ratio changed according to conditions.

  As the metal core 11, a metal shaft obtained by electroless nickel plating on a SUM material having an outer diameter of 6 mm and an axial length of 252 mm was used. The layer thickness of the conductive elastic layer 12 was set to about 3.0 mm. In this case, the outer diameter of the conductive elastic layer 12 is approximately 12.0 mm. Furthermore, the axial length of the conductive elastic layer 12 was set to 224.0 mm.

With respect to the manufactured charging roller 2, (1) physical properties were measured.
(1) Measurement of physical properties The physical properties were measured using the produced charging roller 2 as it was. The measurement method will be described below.

(1-1) Resistance value measurement (resistance unevenness)
For resistance measurement, a high resistance meter 4339B (manufactured by Agilent Technologies) was used. As shown in FIG. 6, a bearing 31 made of a SUS material having a width of 2.0 mm and a diameter of 6.0 mm was brought into contact with the charging roller 2 with a force of 10 gf, and the resistance value with respect to the core metal 11 was measured. There are six bearings 31 from P1 to P6, and measurement was performed by switching in order from P1. Specifically, while rotating the charging roller 2, a resistance value of 600 points in total was measured from P1 to P6 for 100 points per round. The average resistance value at this time was defined as the resistance value of the charging roller 2, and a value obtained by dividing the maximum resistance value by the minimum resistance value was defined as resistance unevenness. In addition, the voltage applied to the core metal 11 at the time of measurement was 300V.

(1-2) Hardness (degree) measurement For measuring the hardness of the conductive elastic layer 12, an A-type Asker hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) and a constant pressure loader (manufactured by Kobunshi Keiki Co., Ltd.) were used. Both ends of the shaft of the core metal 11 were fixed, and the measurement pressure was 1000 gf.

(1-3) Surface Roughness (Maximum Height Ry) Measurement The surface roughness of the conductive elastic layer 12 is measured with a surface roughness meter SE-3500 (manufactured by Kosaka Laboratory) equipped with a detector PU-DJ2S. used. The measurement conditions were based on JIS B0610: 1994, and the cut-off λc was 0.8 mm, the reference length was 0.8 mm, the measurement length was 4.0 mm, and the feed rate was 0.1 mm / s.

[Example 1-1]
In the charging roller 2 of Example 1-1, first, 10 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 3.1 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.9 times. The resistance value in an environment of 10 ° C. and 20% RH was 2.8 × 10 ⁷ Ω, and the resistance unevenness was 4.2 times. Further, the hardness of the charging roller 2 was 74 degrees, and the maximum surface roughness height Ry was 10.6 μm.

[Example 1-2]
In the charging roller 2 of Example 1-2, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 3.5 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.4 times. The resistance value in an environment of 10 ° C. and 20% RH was 3.4 × 10 ⁷ Ω, and the resistance unevenness was 4.6 times. Further, the hardness of the charging roller 2 was 70 degrees, and the maximum height Ry of the surface roughness was 11.2 μm.

[Example 1-3]
In the charging roller 2 of Example 1-3, first, 90 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. are added as conductive agents. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 3.0 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.1 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 9.5 × 10 ⁷ Ω, and the resistance unevenness was 8.6 times. Further, the hardness of the charging roller 2 was 67 degrees, and the maximum height Ry of the surface roughness was 11.7 μm.

[Example 1-4]
In the charging roller 2 of Example 1-4, first, 50 parts by weight of ethylene propylene diene rubber (EPDM) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. as a conductive agent. After adding an appropriate amount, the mixture was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 thus obtained was 4.9 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.3 times. The resistance value in an environment of 10 ° C. and 20% RH was 5.4 × 10 ⁷ Ω, and the resistance unevenness was 4.5 times. Further, the hardness of the charging roller 2 was 61 degrees, and the maximum surface roughness height Ry was 9.2 μm.

[Example 1-5]
In the charging roller 2 of Example 1-5, first, 100 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. are added as conductive agents. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 2.8 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.1 times. The resistance value in a 10 ° C., 20% RH environment was 9.9 × 10 ⁷ Ω, and the resistance unevenness was 8.8 times. Further, the hardness of the charging roller 2 was 66 degrees, and the maximum height Ry of the surface roughness was 12.1 μm.

[Example 1-6]
In the charging roller 2 of Example 1-6, first, 100 parts by weight of ethylene propylene diene rubber (EPDM) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. as a conductive agent. After adding an appropriate amount, the mixture was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 5.6 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.2 times. The resistance value in an environment of 10 ° C. and 20% RH was 8.6 × 10 ⁷ Ω, and the resistance unevenness was 4.3 times. Further, the hardness of the charging roller 2 was 59 degrees, and the maximum surface roughness height Ry was 10.9 μm.

[Example 1-7]
In the charging roller 2 of Example 1-7, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. As the surface treatment liquid, a mixture of 16 parts by weight of an isocyanate compound (HDI) and 4 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate was used. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging roller 2 obtained in this way was 3.7 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.5 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 4.3 × 10 ⁷ Ω, and the resistance unevenness was 5.1 times. Further, the hardness of the charging roller 2 was 71 degrees, and the maximum surface roughness height Ry was 10.4 μm.

[Example 1-8]
In the charging roller 2 of Example 1-8, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 10 parts by weight of an isocyanate compound (HDI) and 10 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging roller 2 obtained in this way was 4.2 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.7 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 7.4 × 10 ⁷ Ω, and the resistance unevenness was 6.8 times. Further, the hardness of the charging roller 2 was 72 degrees, and the maximum height Ry of the surface roughness was 10.7 μm.

[Example 1-9]
In the charging roller 2 of Example 1-9, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) and 5 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging roller 2 thus obtained was 3.9 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.8 times. Moreover, the resistance value in an environment of 10 ° C. and 20% RH was 8.6 × 10 ⁷ Ω, and the resistance unevenness was 7.9 times. Further, the hardness of the charging roller 2 was 72 degrees, and the maximum height Ry of the surface roughness was 9.9 μm.

[Example 1-10]
In the charging roller 2 of Example 1-10, first, 100 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 10 parts by weight of an isocyanate compound (HDI) and 10 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging roller 2 obtained in this way was 3.1 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.5 times. The resistance value in a 10 ° C., 20% RH environment was 10.9 × 10 ⁷ Ω, and the resistance unevenness was 9.1 times. Further, the hardness of the charging roller 2 was 67 degrees, and the maximum height Ry of the surface roughness was 11.7 μm.

[Example 1-11]
In the charging roller 2 of Example 1-11, first, 100 parts by weight of ethylene propylene diene rubber (EPDM) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. as a conductive agent. After adding an appropriate amount, the mixture was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 10 parts by weight of an isocyanate compound (HDI) and 10 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging roller 2 obtained in this way was 6.5 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.7 times. The resistance value in a 10 ° C., 20% RH environment was 10.8 × 10 ⁷ Ω, and the resistance unevenness was 4.7 times. Further, the charging roller 2 had a hardness of 60 degrees, and the maximum surface roughness height Ry was 10.1 μm.

[Example 1-12]
In the charging roller 2 of Example 1-12, first, 10 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 10 parts by weight of an isocyanate compound (HDI) and 10 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging roller 2 obtained in this way was 3.6 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 3.1 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 3.4 × 10 ⁷ Ω, and the resistance unevenness was 5.1 times. Further, the charging roller 2 had a hardness of 75 degrees, and the maximum surface roughness height Ry was 9.8 μm.

[Example 1-13]
In the charging roller 2 of Example 1-13, first, 10 parts by weight of ethylene propylene diene rubber (EPDM) is added to 100 parts by weight of chloroprene rubber (CR), and carbon black, a vulcanizing agent, etc. are used as a conductive agent. After adding an appropriate amount, the mixture was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 10 parts by weight of an isocyanate compound (HDI) and 10 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging roller 2 obtained in this way was 4.0 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 3.4 times. The resistance value in an environment of 10 ° C. and 20% RH was 4.4 × 10 ⁷ Ω, and the resistance unevenness was 6.7 times. Furthermore, the hardness of the charging roller 2 was 72 degrees, and the maximum height Ry of the surface roughness was 12.3 μm.

[Example 1-14]
In the charging roller 2 of Example 1-14, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 15 parts by weight of isocyanate compound (HDI) and 5 parts by weight of silicone diol with respect to 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. The silicone diol having a molecular weight Mw of about 1000 was used.

The resistance value of the charging roller 2 obtained in this way was 2.6 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.1 times. The resistance value in an environment of 10 ° C. and 20% RH was 3.1 × 10 ⁷ Ω, and the resistance unevenness was 3.7 times. Further, the hardness of the charging roller 2 was 69 degrees, and the maximum surface roughness height Ry was 8.7 μm.

[Comparative Example 1-1]
In the charging roller 2 of Comparative Example 1-1, first, 200 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and carbon black, a vulcanizing agent, etc. are added as conductive agents. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 thus obtained was 1.2 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.4 times. The resistance value in an environment of 10 ° C. and 20% RH was 24.6 × 10 ⁷ Ω, and the resistance unevenness was 2.7 times. Further, the charging roller 2 had a hardness of 60 degrees, and the maximum surface roughness height Ry was 13.5 μm.

[Comparative Example 1-2]
In charging roller 2 of Comparative Example 1-2, first, 120 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. are added as conductive agents. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 2.1 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.6 times. The resistance value in an environment of 10 ° C. and 20% RH was 12.9 × 10 ⁷ Ω, and the resistance unevenness was 4.3 times. Further, the hardness of the charging roller 2 was 64 degrees, and the maximum height Ry of the surface roughness was 11.7 μm.

[Comparative Example 1-3]
In the charging roller 2 of Comparative Example 1-3, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. are added as conductive agents. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment of the conductive elastic layer 12 of Comparative Example 1-3 was not performed.

The resistance value of the charging roller 2 obtained in this way was 1.8 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.7 times. The resistance value in a 10 ° C., 20% RH environment was 1.5 × 10 ⁷ Ω, and the resistance unevenness was 2.1 times. Further, the charging roller 2 had a hardness of 69 degrees, and the maximum surface roughness height Ry was 12.1 μm.

[Comparative Example 1-4]
In the charging roller 2 of Example 1-4, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, it was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment solution used was a mixture of 20 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging roller 2 thus obtained was 5.1 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 3.4 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 16.7 × 10 ⁷ Ω, and the resistance unevenness was 15.3 times. Furthermore, the hardness of the charging roller 2 was 73 degrees, and the maximum height Ry of the surface roughness was 10.9 μm.

[Comparative Example 1-5]
In the charging roller 2 of Comparative Example 1-5, first, 100 parts by weight of epichlorohydrin rubber (ECO) and an appropriate amount of carbon black, a vulcanizing agent, etc. as a conductive agent were added, and then kneaded and extruded into a roller shape. . After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 1.1 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.3 times. The resistance value in a 10 ° C., 20% RH environment was 71.0 × 10 ⁷ Ω, and the resistance unevenness was 2.5 times. Furthermore, the hardness of the charging roller 2 was 58 degrees, and the maximum height Ry of the surface roughness was 14.2 μm.

[Comparative Example 1-6]
In the charging roller 2 of Comparative Example 1-6, first, 100 parts by weight of ethylene propylene diene rubber (EPDM) is added to 100 parts by weight of epichlorohydrin rubber (ECO), and carbon black, a vulcanizing agent, etc. are used as a conductive agent. After adding an appropriate amount, the mixture was kneaded and extruded to form a roller. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 2.9 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.1 times. The resistance value in an environment of 10 ° C. and 20% RH was 16.8 × 10 ⁷ Ω, and the resistance unevenness was 3.3 times. Furthermore, the hardness of the charging roller 2 was 55 degrees, and the maximum height Ry of the surface roughness was 13.7 μm.

[Comparative Example 1-7]
In the charging roller 2 of Comparative Example 1-7, first, 100 parts by weight of ethylene propylene diene rubber (EPDM) and, in addition, an appropriate amount of carbon black, a vulcanizing agent, etc. as a conductive agent were added and then kneaded and extruded into a roller shape. Formed. After steam vulcanization at 150 ° C. for 1 hour, it was pressed into a metal shaft and further subjected to secondary vulcanization at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 12 having a layer thickness of 3.0 mm and an outer diameter of 12.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The electroconductive elastic layer 12 was immersed in this surface treatment liquid for 2 minutes and heated at 120 ° C. for 1 hour to obtain a surface treatment layer 13. The temperature of the surface treatment liquid when the conductive elastic layer 12 was immersed was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging roller 2 obtained in this way was 5.6 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 4.3 times. The resistance value in an environment of 10 ° C. and 20% RH was 6.3 × 10 ⁷ Ω, and the resistance unevenness was 5.6 times. Furthermore, the hardness of the charging roller 2 was 52 degrees, and the maximum height Ry of the surface roughness was 15.4 μm.

  By the way, when the main component of the chargeable elastic layer 12 is only chloroprene rubber, the charge elastic layer 12 becomes too hard, and as a result, a sufficient nip is not formed with the photosensitive drum 1. Therefore, since it is predicted that charging unevenness of the photosensitive drum 1 occurs, the evaluation test was not performed on the charging roller 2 in which the main component of the chargeable elastic layer 12 is only chloroprene rubber. When the other rubber is less than 0.1 with respect to the chloroprene rubber 1, the characteristics of the chloroprene rubber become strong, and as a result, the charged elastic layer 12 becomes hard. Therefore, the rubber forming the charging elastic layer 12 is desirably blended with the chloroprene rubber 1 at a ratio of 0.1 or more. If the contact force of the charging roller 2 to the photosensitive drum 1 is increased in order to form a sufficient nip with the photosensitive drum 1, it is expected that the photosensitive layer of the photosensitive drum 1 is peeled off or a rotational load is generated.

  The charging roller 2 produced in the example and the comparative example was incorporated in the printer 100, and (2) an evaluation test was performed. The evaluation method will be described below.

(2) Evaluation Test Printing for the evaluation test was performed using the printer 100 shown in FIG. The outer diameter of the photosensitive drum 1 at this time was 30 mm. A polycarbonate resin was used for the outermost surface layer of the photosensitive drum 1 as a charge transport layer. Further, the axial length of the photosensitive drum 1 was set sufficiently longer than the axial length of the conductive elastic layer 12 of the charging roller 2, and the rotational speed during printing of the photosensitive drum 1 was set to 180 rpm. On the outer peripheral surface of the photosensitive drum 1, both ends of the core metal 11 are pressed by springs with a pressure of 450 gf on one side so that the charging roller 2 contacts with a constant pressure. An evaluation test was performed using the printer 100 having such a configuration. The test method will be described below.

(2-1) Long-term storage evaluation test (contamination of the photosensitive drum 1 and roller dent evaluation of the charging roller 2)
In the long-term storage evaluation test, the contamination of the photosensitive drum 1 after long-term storage and the roller dent of the charging roller 2 were evaluated with the charging roller 2 pressed against the outer peripheral surface of the photosensitive drum 1. Specifically, it is stored for 720 hours (approximately one month) in a state where both ends of the core metal 11 are pressed with a pressure of 500 gf so that the charging roller 2 contacts with a constant pressure on the outer peripheral surface of the photosensitive drum 1. did. The storage environment at this time is three environments of 50 ° C., 90% RH, 50 ° C., 55% RH, and 45 ° C. 90% RH. After long-term storage, the tested photosensitive drum 1 and charging roller 2 were incorporated into the printer 100, and printing was performed at a density of 30% coverage. Here, with respect to the horizontal streak-shaped density step in the charging roller two cycles, the density of the horizontal streak portion is 80% or more with respect to the density other than the horizontal streak generation portion (that is, the normal image portion). , The case of less than 80% was taken as x. For these concentration measurements, a densitometer X-Rite 504 (manufactured by Nippon Flat Plate Co., Ltd.) was used.

  As a result of the concentration measurement, ◯ in all three environments was ◎, x in an environment of 50 ° C. and 90% RH, but × in an environment of 50 ° C., 55% RH, 45 ° C. and 90% RH. What was (circle) was set to x which was (circle) in any environment of (circle), 50 degreeC, 55% RH, 45 degreeC, and 90% RH. Here, if it is ○ in the environment of 50 ° C., 55% RH, 45 ° C., 90% RH, there is no problem in normal use, so even if it is × in the environment of 50 ° C., 90% RH, The evaluation was ○. In the environment of 50 ° C. and 90% RH, “◯” is marked as “◎” because it is particularly excellent for long-term storage.

(2-2) Image evaluation test (density unevenness)
The image evaluation test was performed under two environments of 10 ° C. and 20% RH (low temperature and low humidity: LL) and 28 ° C. and 80% RH (high temperature and high humidity: HH). In addition, the voltage applied to the charging roller 2 at the time of image evaluation was set to four types of DC voltages of -900V, -1000V, -1100V, and -1200V, and printing was performed. Image evaluation is printed by A4 half paper (Excellent White: manufactured by Oki Data Co., Ltd.) as a printing medium, and images used for image evaluation are 30% coverage, 100% coverage, and white background (0% coverage). used. Image defects such as horizontal stripes, vertical stripes, white spots, black spots, white background fog, and density unevenness generated at this time were evaluated.

  The case where the occurrence of horizontal streaks, vertical streaks, white spots, and black spots was indicated as x.

  White background fog is caused by a developer that adheres to a background portion of an image, that is, a non-image portion (white background) by a developer having a low charge amount or a developer charged to a reverse polarity with respect to a normally charged developer. appear. In the white background image, the color difference E between the printing paper before printing and after printing was measured with a spectrocolorimeter (CM2600d: manufactured by Konica Minolta) to evaluate the white background fog. A smaller value of the color difference E indicates that there is less white background fog.

Density unevenness was evaluated by measuring the color difference E in a 30% coverage image. A smaller value of the color difference E indicates less density unevenness. The color difference E is a color difference represented by the CIE 1976 L * a * b * color system, and the value of L *, a *, b * obtained by the CIE 1976 L * a * b * color system is used as the color difference. . If the differences between L *, a *, and b * of the two colors to be compared are L1, a1, and b1, the color difference E can be expressed by the following equation.
E = (L1 ² + a1 ² + b1 ² ) ^1/2

The evaluation standard for the color difference E is set as follows in NBS units (US National Bureau of Standards).
E 0-0.5 trace (feels faint)
E 0.5-1.5 slight (slightly felt)
E 1.5-3.0 noticable
E 3.0-6.0 appreceable (conspicuously felt)
E 6.0-12.0 much (feels great)
E 12.0-very much (feels very large)
In other words, according to the NBS unit, if the color difference E is 1.5 or less, there is a slight difference but it is not so much as to be regarded as a different color. In this evaluation, those having a color difference E of 0.5 or less were marked with ◯, and those with a larger color difference were marked with ×.

(2-3) Continuous printing evaluation test The continuous printing evaluation test is conducted by longitudinal feeding of A4 size paper (Excellent White: manufactured by Oki Data Co., Ltd.) as the printing medium, and the image used for image evaluation uses 30% coverage. did. After continuously printing 5000 sheets and 20000 sheets, the above-described (2-2) image evaluation test was performed. Note that when 20000 sheets were continuously printed, the rotational speed of the photosensitive drum 1 was approximately 100,000.

  The evaluation under the three environments in the long-term storage evaluation test is shown in Table 1 below. The evaluation in the above evaluation method is shown in Table 2 below.

  As shown in Table 1 and Table 2, Examples 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1- In the charging rollers 2 of 10, 1-11, 1-12, 1-13, and 1-14, generally good results could be obtained. For Examples 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, and Examples 1-14, as shown in Table 1, in an environment of 50 ° C. and 90% RH Although the evaluation at x was x, in both environments of 50 ° C., 55% RH, 45 ° C., and 90% RH, it was “good”, and it was a level at which there was no problem in normal use. Moreover, the surface of the electroconductive elastic layer 12 can be hardened by processing with the surface treatment liquid containing an isocyanate compound, and durability can be improved. Furthermore, it was revealed that long-term storage characteristics in a 50 ° C., 90% RH environment can be further improved by adding a polycarbonate polyol to the surface treatment liquid (Examples 1-7, 1). -8, 1-9, 1-10, 1-11, 1-12).

  Examples 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1- The charging rollers 2 of 1, 1-13, and 1-14 exhibit predetermined resistance characteristics in a low temperature and low humidity (LL) environment and a high temperature and high humidity (HH) environment, and there is no great difference between the resistance values. . This result shows that the charging roller 2 according to the present embodiment exhibits stable resistance characteristics even under different environments and can prevent the occurrence of image unevenness.

  In the charging rollers 2 of Comparative Examples 1-1, 1-2, 1-3, 1-5, 1-6, and 1-7, as shown in Table 1, image defects occurred in the long-term storage evaluation test. The cause of the image defect in Comparative Example 1-1 is density unevenness of the charging roller 2 cycles due to the occurrence of bloom on the surface of the conductive elastic layer 12. As a cause of this, it is considered that bloom was generated due to excessive addition of epichlorohydrin rubber, and metal oxides floated on the surface of the conductive elastic layer 12 to affect the charging potential of the photosensitive drum 1. . In addition, in the charging roller 2 of Comparative Example 1-1, pinhole leakage due to the resistance becoming too low was confirmed in a high temperature and high humidity (HH) environment.

  The cause of the image defect in Comparative Example 1-2 is density unevenness of the charging roller 2 cycles due to the depression of the conductive elastic layer 12. The cause of this is that the amount of epichlorohydrin rubber added is not as great as that of Comparative Example 1-1, but the amount of addition is excessive as compared with the Examples. When the added amount of epichlorohydrin rubber is large, the ionic conductivity becomes strong, and the dielectric constant of the conductive elastic layer 12 decreases. It is considered that the resistance unevenness of the charging roller 2 caused by this influences the charging potential of the photosensitive drum 1.

  The cause of the image defect in Comparative Example 1-3 is due to contamination of the photosensitive drum 1. The chargeable elastic layer 12 applied to the charging roller 2 of Comparative Example 1-3 is not subjected to surface treatment with a surface treatment liquid. Therefore, the surface of the chargeable elastic layer 12 is in direct contact with the outer peripheral surface of the photosensitive drum 1. Chloroprene rubber has high adhesiveness, and the chargeable elastic layer 12 sticks to the outer peripheral surface of the photosensitive drum 1 when the surface of the chargeable elastic layer 12 is not treated. Further, since the surface of the chargeable elastic layer 12 is not surface-treated, a part of the substance contained in the chargeable elastic layer 12 is raised on the surface of the chargeable elastic layer 12, and as a result, the photosensitive drum 1 is To contaminate. The result of Comparative Example 1-3 is a result supporting that the surface treatment of the chargeable elastic layer 12 with the surface treatment liquid is important. In addition, pinhole leakage was confirmed in the charging roller 2 of Comparative Example 1-3 in a low temperature and low humidity (LL) environment.

  The cause of the image defect in Comparative Example 1-4 is density unevenness in a low temperature and low humidity (LL) environment. This is considered to be because the surface treatment liquid does not contain an isocyanate compound, so that the surface treatment liquid does not penetrate into the chargeable elastic layer 12 and the polycarbonate-based polyol remains on the surface of the chargeable elastic layer 12. It is done. If the polycarbonate-based polyol remains on the surface of the chargeable elastic layer 12, the resistance on the surface of the chargeable elastic layer 12 increases in a low-temperature and low-humidity (LL) environment, and resistance unevenness increases. As a result, it is considered that density unevenness occurs and an image is defective.

  The cause of the image defect in Comparative Examples 1-5 and 1-6 is considered to be that blooming occurred due to long-term storage, and charging unevenness of the photosensitive drum 1 occurred.

  The cause of the image defect in Comparative Example 1-7 is that the main component of the chargeable elastic layer 12 is only EPDM. Therefore, the charging roller 2 is distorted and stored on the photosensitive drum 1 due to long-term storage. It is thought that it is because of the

  From the above results, in the case of long-term storage by treating the surface of the conductive elastic layer 12 (containing epichlorohydrin rubber or ethylene propylene diene rubber) with a surface treatment liquid containing isocyanate, which is mainly composed of chloroprene rubber. In addition, it is possible to provide the charging roller 2 provided with an elastic layer that prevents the occurrence of bloom or bleed and has stable conductive properties.

  Although 1st Embodiment demonstrated the electroconductive elastic layer 12 which has chloroprene rubber as a main component on the outer peripheral surface of the metal core 11, and the surface treatment layer 13 was provided in the surface of the electroconductive elastic layer 12, it demonstrated. However, the present invention is not limited to this. For example, the conductive elastic layer 12 may be configured by a plurality of layers. In that case, a rubber material in which chloroprene rubber is the main component and other rubber is blended is used for the outermost layer of the conductive elastic layer 12. The outermost layer, that is, the surface treatment layer 13 may be provided on the surface of the conductive elastic layer 12.

  In the present invention, attention is paid to the portion facing the photosensitive drum, so that the outermost layer of the conductive elastic layer, that is, the conductive elastic layer can be used even if the entire conductive elastic layer is not a layer mainly composed of chloroprene rubber. The layer closest to the photosensitive drum may be a layer mainly composed of chloroprene rubber.

[Second Embodiment]
The charging device 3 in the second embodiment will be described as including a charging blade 40 in place of the charging roller 2 shown in the first embodiment. Generally, the charging blade 40 is inferior in durability to the charging roller 2 but has the advantages of reducing the size and cost of the charging member. Therefore, by using the charging device 3 including the charging blade 40, the image forming unit 20 and the printer 100 can be reduced in size and cost.

  Hereinafter, the second embodiment will be described. Since the configuration and printing operation of the image forming unit 20 and the printer 100 according to the second embodiment are substantially the same as those described in the first embodiment, they are the same. The same reference numerals are given to those, and the description is omitted.

  As shown in FIG. 7, the charging device 3 includes a charging blade 40 that uniformly charges the outer peripheral surface of the photosensitive drum 1, and a charging device power supply 14 b that applies a DC voltage to the charging blade 40.

  The charging blade 40 is provided so as to be in contact with the photosensitive drum 1 in the same manner as the charging roller 2. The charging blade 40 is in sliding contact with the rotation of the photosensitive drum 1 to charge the outer peripheral surface of the photosensitive drum 1.

  As shown in FIG. 8, such a charging blade 40 has a conductive elastic layer 42 provided on one side surface of a conductive guide member 41 to which a voltage is applied from the charging device power supply 14b. A surface treatment layer 43 is uniformly provided on the surface of the elastic layer 42.

  As the guide member 41, for example, a metal sheet metal can be used. The conductive elastic layer 42 may be a conductive rubber elastic layer containing the conductive agent described in the first embodiment. The surface treatment layer 43 on the conductive elastic layer 42 can be formed using the surface treatment liquid described in the first embodiment. The surface treatment layer 43 may be provided on the entire surface of the conductive elastic layer 42, or may be provided only on a portion where the conductive elastic layer 42 is in contact with the photosensitive drum 1.

  In the examples described below, similarly to Example 1, chloropyrene rubber was used as the main component, and the conductive elastic layer 42 was produced by changing the blending ratio of the additives to be blended. In addition, the surface treatment of the conductive elastic layer 42 was performed using a surface treatment liquid whose composition ratio was changed according to conditions.

  As the guide member 41, a metal plate obtained by electroless nickel plating on a SUM material having a thickness of 0.5 mm and 252.0 × 5.0 mm was used. The conductive elastic layer 42 has a layer thickness of 2.0 mm and a strip shape of 224.0 × 10.0 mm. Furthermore, the adjusted conductive elastic layer 42 was bonded and fixed to the guide member 41 using an adhesive.

The manufactured charging blade 40 was subjected to (3) physical property measurement described below.
(3) Physical property measurement The physical property measurement was performed using the produced charging blade 40 as it was. The measurement method will be described below.

(3-1) Resistance value measurement (resistance unevenness)
For resistance measurement, a high resistance meter 4339B (manufactured by Agilent Technologies) was used. As shown in FIG. 9, a SUS material bearing 45 having a width of 2.0 mm and a diameter of 6.0 mm was brought into contact with the charging blade 40 with a force of 20 gf, and the resistance value between the guide member 41 and the bearing was measured. A total of 220 point resistance values were measured every 1.0 mm while moving the bearing 45 in the longitudinal direction at the contact portion of the charging blade 40 excluding 2 mm at both ends with the photosensitive drum 1. The average resistance value at this time was defined as the resistance value of the charging blade 40, and a value obtained by dividing the maximum resistance value by the minimum resistance value was defined as resistance unevenness. The applied voltage to the guide member 41 at the time of measurement was 300V.

(3-2) Hardness (degree) measurement The hardness of the conductive elastic layer 42 is measured using a micro rubber hardness meter MD-1 Capa type A (manufactured by Kobunshi Keiki Co., Ltd.), and the photosensitive drum of the charging blade 40. The hardness of the contact surface with 1 was measured.

(3-3) Surface Roughness (Maximum Height Ry) Measurement The surface roughness of the conductive elastic layer 42 was measured in the same manner as in Example 1.

[Example 2-1]
In the charging blade 40 of Example 2-1, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, they were kneaded and extruded into a strip shape. After steam vulcanization at 150 ° C. for 1 hour, secondary vulcanization was further performed at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 42 having a layer thickness of 2.0 mm and 224.0 × 10.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 25 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The surface treatment layer 43 was obtained by immersing the conductive elastic layer 12 in this surface treatment solution for 2 minutes and heating at 120 ° C. for 1 hour. The temperature of the surface treatment liquid when dipping the conductive elastic layer 42 was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging blade 42 thus obtained was 4.2 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.7 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 4.4 × 10 ⁷ Ω, and the resistance unevenness was 4.2 times. Further, the charging blade 40 had a hardness of 71 degrees, and the maximum height Ry of the surface roughness was 7.9 μm.

[Example 2-2]
In the charging blade 40 of Example 2-2, first, 50 parts by weight of ethylene propylene diene rubber (EPDM) is added to 100 parts by weight of chloroprene rubber (CR), and carbon black, a vulcanizing agent, etc. are used as a conductive agent. After adding an appropriate amount, the mixture was kneaded and extruded into a strip shape. After steam vulcanization at 150 ° C. for 1 hour, secondary vulcanization was further performed at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 42 having a layer thickness of 2.0 mm and 224.0 × 10.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 25 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The surface treatment layer 43 was obtained by immersing the conductive elastic layer 12 in this surface treatment solution for 2 minutes and heating at 120 ° C. for 1 hour. The temperature of the surface treatment liquid when dipping the conductive elastic layer 42 was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging blade 42 thus obtained was 5.6 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.6 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 6.1 × 10 ⁷ Ω, and the resistance unevenness was 4.3 times. Furthermore, the charging blade 40 had a hardness of 61 degrees, and the maximum surface roughness height Ry was 6.9 μm.

[Example 2-3]
In the charging blade 40 of Example 2-1, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, they were kneaded and extruded into a strip shape. After steam vulcanization at 150 ° C. for 1 hour, secondary vulcanization was further performed at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 42 having a layer thickness of 2.0 mm and 224.0 × 10.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 20 parts by weight of an isocyanate compound (HDI) and 5 parts by weight of a polycarbonate-based polyol with respect to 100 parts by weight of ethyl acetate. The surface treatment layer 43 was obtained by immersing the conductive elastic layer 12 in this surface treatment solution for 2 minutes and heating at 120 ° C. for 1 hour. The temperature of the surface treatment liquid when dipping the conductive elastic layer 42 was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging blade 42 thus obtained was 4.1 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.8 times. Further, the resistance value in a 10 ° C., 20% RH environment was 4.9 × 10 ⁷ Ω, and the resistance unevenness was 5.1 times. Further, the charging blade 40 had a hardness of 72 degrees, and the maximum height Ry of the surface roughness was 7.5 μm.

[Example 2-4]
In the charging blade 40 of Example 2-4, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, they were kneaded and extruded into a strip shape. After steam vulcanization at 150 ° C. for 1 hour, secondary vulcanization was further performed at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 42 having a layer thickness of 2.0 mm and 224.0 × 10.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 12.5 parts by weight of an isocyanate compound (HDI) and 12.5 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The surface treatment layer 43 was obtained by immersing the conductive elastic layer 12 in this surface treatment solution for 2 minutes and heating at 120 ° C. for 1 hour. The temperature of the surface treatment liquid when dipping the conductive elastic layer 42 was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging blade 42 thus obtained was 4.9 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.0 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 6.5 × 10 ⁷ Ω, and the resistance unevenness was 6.7 times. Furthermore, the hardness of the charging blade 40 was 73 degrees, and the maximum height Ry of the surface roughness was 7.3 μm.

[Example 2-5]
In the charging blade 40 of Example 2-5, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. are added as conductive agents. Thereafter, they were kneaded and extruded into a strip shape. After steam vulcanization at 150 ° C. for 1 hour, secondary vulcanization was further performed at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 42 having a layer thickness of 2.0 mm and 224.0 × 10.0 mm was obtained by polishing. As the surface treatment liquid, a mixture of 20 parts by weight of an isocyanate compound (HDI) and 5 parts by weight of a silicone diol with respect to 100 parts by weight of ethyl acetate was used. The surface treatment layer 43 was obtained by immersing the conductive elastic layer 12 in this surface treatment solution for 2 minutes and heating at 120 ° C. for 1 hour. The temperature of the surface treatment liquid when dipping the conductive elastic layer 42 was always maintained at 23 ± 2 ° C. The silicone diol having a molecular weight Mw of about 1000 was used.

The resistance value of the charging blade 42 thus obtained was 3.4 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.4 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 4.3 × 10 ⁷ Ω, and the resistance unevenness was 3.9 times. Further, the charging blade 40 had a hardness of 70 degrees, and the maximum height Ry of the surface roughness was 6.8 μm.

[Comparative Example 2-1]
In the charging blade 40 of Comparative Example 2-1, first, 200 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. are added as conductive agents. Thereafter, they were kneaded and extruded into a strip shape. After steam vulcanization at 150 ° C. for 1 hour, secondary vulcanization was further performed at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 42 having a layer thickness of 2.0 mm and 224.0 × 10.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 25 parts by weight of an isocyanate compound (HDI) per 100 parts by weight of ethyl acetate. The surface treatment layer 43 was obtained by immersing the conductive elastic layer 12 in this surface treatment solution for 2 minutes and heating at 120 ° C. for 1 hour. The temperature of the surface treatment liquid when dipping the conductive elastic layer 42 was always maintained at 23 ± 2 ° C. In addition, an isocyanate compound having a molecular weight Mw of approximately 800 was used.

The resistance value of the charging blade 42 thus obtained was 1.4 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 1.3 times. The resistance value in an environment of 10 ° C. and 20% RH was 26.9 × 10 ⁷ Ω, and the resistance unevenness was 2.6 times. Further, the charging blade 40 had a hardness of 61 degrees, and the maximum surface roughness height Ry was 10.1 μm.

[Comparative Example 2-2]
In the charging blade 40 of Comparative Example 2-2, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and an appropriate amount of carbon black, a vulcanizing agent, etc. is added as a conductive agent. Thereafter, they were kneaded and extruded into a strip shape. After steam vulcanization at 150 ° C. for 1 hour, secondary vulcanization was further performed at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 42 having a layer thickness of 2.0 mm and 224.0 × 10.0 mm was obtained by polishing. The surface treatment of the conductive elastic layer 42 of Comparative Example 2-2 was not performed.

The resistance value of the charging blade 42 thus obtained was 2.1 × 10 ⁷ Ω in a 28 ° C., 80% RH environment, and the resistance unevenness was 1.2 times. The resistance value in a 10 ° C., 20% RH environment was 1.9 × 10 ⁷ Ω, and the resistance unevenness was 1.8 times. Further, the charging blade 40 had a hardness of 68 degrees, and the maximum surface roughness height Ry was 8.2 μm.

[Comparative Example 2-3]
In the charging blade 40 of Comparative Example 2-3, first, 50 parts by weight of epichlorohydrin rubber (ECO) is added to 100 parts by weight of chloroprene rubber (CR), and in addition, carbon black, a vulcanizing agent, etc. are added as conductive agents. Thereafter, they were kneaded and extruded into a strip shape. After steam vulcanization at 150 ° C. for 1 hour, secondary vulcanization was further performed at 150 ° C. for 1 hour. After cooling to room temperature, the conductive elastic layer 42 having a layer thickness of 2.0 mm and 224.0 × 10.0 mm was obtained by polishing. The surface treatment liquid used was a mixture of 25 parts by weight of a polycarbonate polyol with respect to 100 parts by weight of ethyl acetate. The surface treatment layer 43 was obtained by immersing the conductive elastic layer 12 in this surface treatment solution for 2 minutes and heating at 120 ° C. for 1 hour. The temperature of the surface treatment liquid when dipping the conductive elastic layer 42 was always maintained at 23 ± 2 ° C. In addition, a polycarbonate polyol having a molecular weight Mw of about 900 was used.

The resistance value of the charging blade 42 thus obtained was 6.3 × 10 ⁷ Ω in an environment of 28 ° C. and 80% RH, and the resistance unevenness was 2.1 times. Further, the resistance value in an environment of 10 ° C. and 20% RH was 19.2 × 10 ⁷ Ω, and the resistance unevenness was 13.1 times. Furthermore, the hardness of the charging blade 40 was 74 degrees, and the maximum height Ry of the surface roughness was 7.3 μm.

  The charging blade 40 produced in the example and the comparative example was incorporated in the printer 100, and (4) an evaluation test was performed. The evaluation method will be described below.

(4) Evaluation Test Printing for the evaluation test was performed in the same manner as the test described in Example 1.

(4-1) Long-term storage evaluation test (contamination of the photosensitive drum 1)
In the long-term storage evaluation test, the contamination of the photosensitive drum 1 after long-term storage was evaluated with the charging blade 40 pressed against the outer peripheral surface of the photosensitive drum 1. Specifically, the photosensitive drum 1 was stored for 720 hours (approximately one month) in a state of being pressed with a linear pressure of 40 gf so that the charging blade 40 abuts with a constant pressure on the outer peripheral surface of the photosensitive drum 1. The storage environment at this time is three environments of 50 ° C., 90% RH, 50 ° C., 55% RH, and 45 ° C. 90% RH. After long-term storage, the tested photosensitive drum 1 and charging roller 2 were incorporated into the printer 100, and printing was performed at a density of 30% coverage. Here, with respect to the horizontal streak-shaped density step in the charging roller two cycles, the density of the horizontal streak portion is 80% or more with respect to the density other than the horizontal streak generation portion (that is, the normal image portion). , The case of less than 80% was taken as x. For these concentration measurements, a densitometer X-Rite 504 (manufactured by Nippon Flat Plate Co., Ltd.) was used.

  As a result of the concentration measurement, ◯ in all three environments was ◎, x in an environment of 50 ° C. and 90% RH, but × in an environment of 50 ° C., 55% RH, 45 ° C. and 90% RH. What was (circle) was set to x which was (circle) in any environment of (circle), 50 degreeC, 55% RH, 45 degreeC, and 90% RH. Here, if it is ○ in the environment of 50 ° C., 55% RH, 45 ° C., 90% RH, there is no problem in normal use, so even if it is × in the environment of 50 ° C., 90% RH, The evaluation was ○. In the environment of 50 ° C. and 90% RH, “◯” is marked as “◎” because it is particularly excellent for long-term storage.

(4-2) Image evaluation test (density unevenness)
The image evaluation test was performed in the same manner as the test described in Example 1.

(4-3) Pinhole Leak Evaluation Test In the pinhole leak evaluation test, a scratch of Φ0.3.0 mm is applied to the outer peripheral surface of the photosensitive drum 1 until it reaches the conductive support, and (4-2) an image evaluation test is performed. went.

(4-4) Continuous Printing Evaluation Test The continuous printing evaluation test was performed by longitudinal feeding of A4 semi-paper (Excellent White: manufactured by Oki Data Co., Ltd.) as a printing medium, and an image used for image evaluation used 30% coverage. After continuously printing 1000 sheets and 5000 sheets, the above-described (4-2) image evaluation test was performed.

  The evaluation under the three environments in the long-term storage evaluation test is shown in Table 3 below. The evaluation in the above evaluation method is shown in Table 4 below.

  As shown in Tables 3 and 4, in the charging blades 40 of Examples 2-1, 2-2, 2-3, 2-4, and 2-5, generally good results could be obtained. About Example 2-1, 2-2, and Example 2-5, as shown in Table 3, evaluation in 50 degreeC and 90% RH environment was x, but 50 degreeC, 55% RH, In both environments of 45 ° C. and 90% RH, the evaluation was “◯”, which was a level that was not a problem for normal use. Moreover, the surface of the electroconductive elastic layer 42 can be hardened and it can improve durability by processing with the surface treatment liquid containing an isocyanate compound. Furthermore, it was revealed that the long-term storage characteristics in a 50 ° C., 90% RH environment can be further improved by adding a polycarbonate polyol to the surface treatment liquid (Examples 2-3 and 2). -4).

  In addition, the charging blade 42 of Examples 2-1, 2-2, 2-3, 2-4, and 2-5 has a predetermined resistance in a low temperature and low humidity (LL) environment and a high temperature and high humidity (HH) environment. It shows the characteristics and there is no big difference between the resistance values. This result shows that the charging roller 2 according to the present embodiment exhibits stable resistance characteristics even under different environments and can prevent the occurrence of image unevenness.

  In the charging blades 40 of Comparative Examples 2-1, 2-2, and 2-3, as shown in Table 3, image defects occurred in the long-term storage evaluation test. The cause of the image defect in Comparative Example 2-1 is due to pinhole leak in a high temperature and high humidity (HH) environment. This is considered to be because resistance becomes too low in a high temperature and high humidity (HH) environment. Even if the amount of conductive agent added is reduced so that the resistance does not decrease in a high temperature and high humidity (HH) environment, the resistance becomes too high in a low temperature and low humidity (LL) environment, and normal charging can be performed. There is a risk of disappearing.

  The cause of the image failure in Comparative Example 2-2 is due to contamination of the photosensitive drum 1. The chargeable elastic layer 42 applied to the charging blade 40 of Comparative Example 2-2 is not subjected to surface treatment with a surface treatment liquid. Accordingly, the surface of the chargeable elastic layer 42 is in direct contact with the outer peripheral surface of the photosensitive drum 1. Chloroprene rubber has high adhesiveness, and the chargeable elastic layer 42 sticks to the outer peripheral surface of the photosensitive drum 1 when the surface of the chargeable elastic layer 42 is not treated. In addition, since the surface of the chargeable elastic layer 42 is not surface-treated, a part of the substance contained in the chargeable elastic layer 42 floats on the surface of the chargeable elastic layer 42. To contaminate. The result of Comparative Example 2-3 confirms that the surface treatment of the chargeable elastic layer 42 with the surface treatment liquid is important. In addition, pinhole leakage was confirmed in the charging blade 40 of Comparative Example 2-2 in a low temperature and low humidity (LL) environment.

  The cause of the image defect in Comparative Example 2-3 is density unevenness in a low temperature and low humidity (LL) environment. This is considered to be because the surface treatment liquid does not contain an isocyanate compound, so that the surface treatment liquid does not penetrate into the chargeable elastic layer 42 and the polycarbonate-based polyol remains on the surface of the chargeable elastic layer 42. It is done. When the polycarbonate-based polyol remains on the surface of the chargeable elastic layer 42, the resistance on the surface of the chargeable elastic layer 42 increases in a low temperature and low humidity (LL) environment, and resistance unevenness increases. As a result, it is considered that density unevenness occurs and an image is defective.

  From the above results, when the surface of the conductive elastic layer 42 (containing epichlorohydrin rubber or ethylene propylene diene rubber) is mainly treated with chloroprene rubber and treated with a surface treatment liquid containing isocyanate, In addition, it is possible to provide the charging blade 42 including an elastic layer that prevents the occurrence of bloom or bleed and has stable conductive characteristics.

  In the present invention, attention is paid to the portion facing the photosensitive drum, so that the outermost layer of the conductive elastic layer, i.e., the conductive elastic layer, even if the entire conductive elastic layer is not a layer mainly composed of chloroprene rubber. The layer closest to the photosensitive drum may be a layer mainly composed of chloroprene rubber. Therefore, the outermost layer of the conductive elastic layer 42, that is, the layer closest to the photosensitive drum in the conductive elastic layer may be a layer using a rubber material in which chloroprene rubber is the main component and other rubber is blended. And you may be the form by which the surface treatment layer 43 is provided in the surface of the said outermost layer, ie, a conductive elastic layer.

  The charging device, the image forming unit, and the image forming apparatus according to the present invention are not limited to the illustrated examples described above, and various changes can be made without departing from the scope of the present invention. .

1 is a schematic configuration diagram of a printer 100. FIG. 2 is a schematic configuration diagram of an image forming unit 20. FIG. 2 is a schematic configuration diagram of a charging device 3. FIG. 2 is a diagram illustrating a charging roller 2. FIG. 2 is a diagram illustrating a charging roller 2. FIG. It is a figure explaining resistance value measurement. 2 is a schematic configuration diagram of a charging device 3. FIG. 3 is a diagram illustrating a charging blade 40. FIG. It is a figure explaining resistance value measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 Charging apparatus 4 Developing apparatus 5 Developer 6 Developer box 7 Developing roller 8 Cleaning apparatus 9 Cleaning blade 10 Waste developer tank 11 Core metal 12 Conductive elastic layer 13 Surface treatment layer 14a Charging apparatus power supply 14b Charging device power supply 20 Image forming unit 21 Exposure device 22 Transfer device 23 Fixing device 24 Paper 25 Paper feed roller 26a Transport guide 26b Transport guide 27 Transport roller 28 Discharge roller 29 Stacker 30 High resistance meter 31 Bearing 40 Charging blade 41 Guide member 42 Conductivity Elastic layer 43 Surface treatment layer

Claims (11)

A conductive metal body;
An elastic layer formed on the metal body;
A power supply unit connected to the metal body and applying a voltage to the metal body,
At least the outermost layer of the elastic layer is a layer mainly composed of chloroprene rubber,
The charging device according to claim 1, wherein the elastic layer has a surface treated with a treatment liquid containing isocyanate.   The charging device according to claim 1, wherein the outermost layer contains epichlorohydrin rubber.   The charging device according to claim 1, wherein the outermost layer contains ethylene propylene diene rubber.   The charging device according to claim 1, wherein the elastic layer contains carbon black.   The charging device according to claim 1, wherein the treatment liquid contains a polycarbonate-based polyol. An image carrier on which an electrostatic latent image is formed;
An image forming unit provided with a charging member provided in contact with the image carrier and charging the image carrier;
The charging member is
A conductive metal body;
An image forming unit, characterized in that it is formed on the metal body, the surface is treated with a treatment liquid containing isocyanate, and at least the outermost layer comprises an elastic layer mainly composed of chloroprene rubber.   The image forming unit according to claim 6, wherein the outermost layer contains epichlorohydrin rubber.   The image forming unit according to claim 6, wherein the outermost layer contains ethylene propylene diene rubber.   The image forming unit according to claim 6, wherein the elastic layer contains carbon black.   The image forming unit according to claim 6, wherein the processing liquid contains a polycarbonate-based polyol.   An image forming apparatus comprising the image forming unit according to claim 6.