To obtain a clear image by making dispersion expressed by maximum/ minimum values of volume or surface resistivity of each part of a tube a specified range and specifying a change in resistivity expressed by maximum/ minimum values between arbitrary locations on the tube.
In a tube, dispersion of volume resistivity or surface resistivity is made within 100 times. Because charged electric charge moves to low resistance if a rate of change in resistance is not a certain fixed rate, a rate of change in volume resistivity and surface resistivity is made within 8 in maximum value/minimum value between arbitrary 20 mm on the tube. In the formation of the tube, thermoplastic resin plastic into which conducting filler is blended is fed from an extruding machine 11 to a spiral groove 12d of an annular die 12, the plastic is extruded in a tube shape from an annular slit 12a, the plastic is passed through a cooling air curtain from a heated and/or cooled ring 17, the plastic is cooled, being brought into slidable contact on an outer peripheral surface of a mandrel for cooling, the plastic is received by a nip roll 18 and the plastic is cut to a prescribed length. Therefore, when this plastic is used for a seamless photosensitive body belt, a clear image can be obtained.
OTSU NORIHIRO
FURUTA KATSUHIRO
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