Abstract: An inventive charging roller (1) includes a roller body (2) which is formed of a crosslinked product of a rubber composition containing a rubber component including 30 to 70 parts by mass of GECO, 15 to 60 parts by mass of IR and not less than 1 part by mass of SBR and/or NBR based on 100 parts by mass of the overall rubber component and has an outer peripheral surface (5) finished in a finish-polished surface. An inventive production method includes the steps of: forming a roller body (2) from the crosslinked product of the rubber composition described above; and wet-polishing or mirror-polishing an outer peripheral surface (5) of the roller body (2) into a finish-polished surface.

Abstract: A developing roller has a roller main body including a cylindrical inner layer constituted by an elastic material and an outer layer constituted by a crosslinked product of a rubber composition in which an epichlorohydrin rubber, a nonpolar diene rubber, and LIR are included, and polar diene rubbers are not included or polar diene rubbers are included in a proportion of less than 20 parts by mass with respect to 100 parts by mass of the total amount of the rubbers, and carbon black is not included or carbon black having an amount of iodine absorbed of 40 mg/g or less is included in a proportion of less than 10 parts by mass with respect to 100 parts by mass of the total amount of the rubbers.

Abstract: A rubber composition which is possible to form a conductive roller having a roller main body having a higher flexibility than in the current situation and having excellent image durability while maintaining the volume resistivity of a roller main body in a range suitable for a developing roller and the like. The rubber composition contains rubbers including 15 parts by mass or more of an EPDM having a Mooney viscosity ML1+4 (100° C.) of 10 or less with respect to 100 parts by mass of the total amount of rubbers and a diene rubber, and less than 25 parts by mass of carbon black with respect to 100 parts by mass of the total amount of rubbers. A conductive roller has a roller main body constituted by the rubber composition.

Abstract: Provided is a development roller which is capable of improving a black solid density and a 2-dot density simultaneously to form a satisfactory image with excellent contrast and thin line reproducibility. A development roller includes a roller body that contains a tubular inner layer consisting of an elastic material and an outer layer consisting of an elastic material, a roller resistance value R1 (?, an applied voltage of 400 V) in a state when there is only the inner layer satisfies formula (1): 6.5?log R1?9.5??(1), and a volume resistivity R2 (?·cm, an applied voltage of 400 V) in a state when there is only the outer layer satisfies formula (2): log R2?9.0??(2).

Abstract: A developing roller has a roller main body including a cylindrical inner layer constituted by an elastic material and an outer layer constituted by a crosslinked product of a rubber composition in which an epichlorohydrin rubber, a nonpolar diene rubber, and LIR are included, and polar diene rubbers are not included or polar diene rubbers are included in a proportion of less than 20 parts by mass with respect to 100 parts by mass of the total amount of the rubbers, and carbon black is not included or carbon black having an amount of iodine absorbed of 40 mg/g or less is included in a proportion of less than 10 parts by mass with respect to 100 parts by mass of the total amount of the rubbers.

Abstract: A semiconductive roller is provided, which includes a roller body made of a crosslinked product of a rubber composition containing a rubber component including epichlorohydrin rubber and diene rubber, and a crosslinking component including: (a) 4,4?-dithiodimorpholine; (b) sulfur; (c) a thiourea compound; and (d) a thiuram accelerating agent; wherein the proportion R (part by mass) of 4,4?-dithiodimorpholine and the proportion S (part by mass) of sulfur based on 100 parts by mass of the overall rubber component satisfy the following expressions (1) and (2): 2R?S??(1) 0.5R+S>0.4??(2).

Abstract: Provided is a development roller which is capable of improving a black solid density and a 2-dot density simultaneously to form a satisfactory image with excellent contrast and thin line reproducibility. A development roller includes a roller body that contains a tubular inner layer consisting of an elastic material and an outer layer consisting of an elastic material, a roller resistance value R1 (?, an applied voltage of 400 V) in a state when there is only the inner layer satisfies formula (1): 6.5?log R1?9.5??(1), and a volume resistivity R2 (?·cm, an applied voltage of 400 V) in a state when there is only the outer layer satisfies formula (2): log R2?9.0??(2).

Abstract: An inventive charging roller (1) includes a roller body (2) which is formed of a crosslinked product of a rubber composition containing a rubber component including 30 to 70 parts by mass of GECO, 15 to 60 parts by mass of IR and not less than 1 part by mass of SBR and/or NBR based on 100 parts by mass of the overall rubber component and has an outer peripheral surface (5) finished in a finish-polished surface. An inventive production method includes the steps of: forming a roller body (2) from the crosslinked product of the rubber composition described above; and wet-polishing or mirror-polishing an outer peripheral surface (5) of the roller body (2) into a finish-polished surface.

Abstract: A semiconductive roller is provided which includes a roller body including a tubular inner layer of an inner layer elastic material containing a softener, and an outer layer of an outer layer elastic material provided on an outer periphery of the inner layer. The outer layer elastic material has a swelling percentage of not higher than 1% as measured when the outer layer elastic material is immersed in the softener at 100° C. for 24 hours. Thus, the semiconductive roller has proper flexibility to be substantially free from imaging failures such as white voids, image density reduction and fogging, and is less liable to cause the contamination of a photoreceptor body and the like and the associated defective image formation which may otherwise occur due to the bleeding of the softener.

Abstract: A semiconductive roller is provided, which includes a roller body made of a crosslinked product of a rubber composition containing a rubber component including epichlorohydrin rubber and diene rubber, and a crosslinking component including: (a) 4,4?-dithiodimorpholine; (b) sulfur; (c) a thiourea compound; and (d) a thiuram accelerating agent; wherein the proportion R (part by mass) of 4,4?-dithiodimorpholine and the proportion S (part by mass) of sulfur based on 100 parts by mass of the overall rubber component satisfy the following expressions (1) and (2): 2R?S??(1) 0.5R+S>0.4??(2).

Abstract: A semiconductive roller is provided which includes a roller body including a tubular inner layer of an inner layer elastic material containing a softener, and an outer layer of an outer layer elastic material provided on an outer periphery of the inner layer. The outer layer elastic material has a swelling percentage of not higher than 1% as measured when the outer layer elastic material is immersed in the softener at 100° C. for 24 hours. Thus, the semiconductive roller has proper flexibility to be substantially free from imaging failures such as white voids, image density reduction and fogging, and is less liable to cause the contamination of a photoreceptor body and the like and the associated defective image formation which may otherwise occur due to the bleeding of the softener.

Abstract: An electroconductive roller is provided, which is imparted with lower resistance than a prior-art electroconductive roller without addition of an expensive salt and an electron conductive agent liable to cause various problems or by adding the electron conductive agent in a smaller proportion that hardly causes the problems, and an image forming apparatus employing the electroconductive roller is also provided. The electroconductive roller (1) includes a tubular base layer (4) made of an ion-conductive elastic material, and a surface layer (6) provided on an outer peripheral surface (5) of the base layer (4). The roller resistance R1 (?) of the base layer and the surface resistance R2 (?) of an outer peripheral surface (7) of the surface layer satisfy all the following expressions (1) to (3): log R1?log R2?2.5??(1) log R1?7.0??(2) log R2?4.0??(3) The image forming apparatus incorporates the electroconductive roller as a charging roller.

Abstract: A developing roller is provided, which is capable of controlling a solid black density and a dot density at higher levels than currently available levels. An image forming apparatus employing the developing roller is also provided. The developing roller (1) includes a tubular base layer (4) of an elastic material, and a surface layer (6) of an elastic material provided on an outer peripheral surface (5) of the base layer (4), wherein the thickness d1 (mm) of the surface layer, the roller resistance R? (log ? as measured with an application voltage of 10 V) of the base layer, and the roller resistance R (log ? as measured with an application voltage of 100 V) of a stack including the base layer and the surface layer satisfy the following expressions (1) to (3): 1.0?R?R???(1) 0.1?d1?2??(2) 7.5?R?8.5??(3) The image forming apparatus incorporates the developing roller.

Abstract: A developing roller is provided, which is capable of controlling a solid black density and a dot density at higher levels than currently available levels. An image forming apparatus employing the developing roller is also provided. The developing roller (1) includes a tubular base layer (4) of an elastic material, and a surface layer (6) of an elastic material provided on an outer peripheral surface (5) of the base layer (4), wherein the thickness d1 (mm) of the surface layer, the roller resistance R? (log ? as measured with an application voltage of 10 V) of the base layer, and the roller resistance R (log ? as measured with an application voltage of 100 V) of a stack including the base layer and the surface layer satisfy the following expressions (1) to (3): 1.0?R?R???(1) 0.1?d1?2??(2) 7.5?R?8.5??(3) The image forming apparatus incorporates the developing roller.

Abstract: An electroconductive roller is provided, which is imparted with lower resistance than a prior-art electroconductive roller without addition of an expensive salt and an electron conductive agent liable to cause various problems or by adding the electron conductive agent in a smaller proportion that hardly causes the problems, and an image forming apparatus employing the electroconductive roller is also provided. The electroconductive roller (1) includes a tubular base layer (4) made of an ion-conductive elastic material, and a surface layer (6) provided on an outer peripheral surface (5) of the base layer (4). The roller resistance R1 (?) of the base layer and the surface resistance R2 (?) of an outer peripheral surface (7) of the surface layer satisfy all the following expressions (1) to (3): log R1?log R2?2.5??(1) log R1?7.0??(2) log R2?4.0??(3) The image forming apparatus incorporates the electroconductive roller as a charging roller.