A rubber foam tube (5) is produced by extruding a rubber composition into a tubular body (4) and feeding the tubular body (4) in an elongated state without cutting to pass the tubular body (4) through a microwave crosslinking device (8) and then through a hot air crosslinking device (9) for continuously foaming and crosslinking the rubber composition. At this time, a ratio V2/V1 between a speed V2 at which the tubular body (4) passes through the hot air crosslinking device (9) and a speed V1 at which the tubular body (4) passes through the microwave crosslinking device (8) is not less than 1.0 and not greater than 1.6.

A rubber foam tube (5) is produced by extruding a rubber composition into a tubular body (4) and feeding the tubular body (4) in an elongated state without cutting to pass the tubular body (4) through a microwave crosslinking device (8) and then through a hot air crosslinking device (9) for continuously foaming and crosslinking the rubber composition. At this time, a ratio V2/V1 between a speed V2 at which the tubular body (4) passes through the hot air crosslinking device (9) and a speed V1 at which the tubular body (4) passes through the microwave crosslinking device (8) is not less than 1.0 and not greater than 1.6.

A semiconductive roller (1) is produced by: preparing a rubber composition containing a rubber component including an NBR and an EPDM in a mass ratio of NBR/EPDM=70/30 to 30/70, at least one selected from the group consisting of SAF, ISAF and HAF, sulfur, a peroxide crosslinking agent and a sulfenamide accelerating agent; extruding the rubber composition into a tubular body; crosslinking the tubular body in a vulcanization can or with the use of a continuous crosslinking apparatus; and forming an oxide film (5) in an outer peripheral surface (4) of the tubular body by irradiation with ultraviolet radiation with a shaft (3) inserted through the tubular body.

Provided is a blowoff nozzle that blows out air to a film being conveyed, the blowoff nozzle including: first and second inscribed portions provided inside the blowoff nozzle, spaced apart in a film conveyance direction, and spaced from a virtual plane passing through an opening portion surface of an opening portion of the blowoff nozzle, the opening portion surface being a surface from which the air is blown out. The first and second inscribed portions have inclined surfaces inclined with respect to the virtual plane, respectively, and the two inclined surfaces are inclined to approach each other toward the virtual plane.

Provided is a blowoff nozzle that blows out air to a film being conveyed, the blowoff nozzle including: first and second inscribed portions provided inside the blowoff nozzle, spaced apart in a film conveyance direction, and spaced from a virtual plane passing through an opening portion surface of an opening portion of the blowoff nozzle, the opening portion surface being a surface from which the air is blown out. The first and second inscribed portions have inclined surfaces inclined with respect to the virtual plane, respectively, and the two inclined surfaces are inclined to approach each other toward the virtual plane.

A stretching unit for stretching a film is disclosed having an oven and a compensation device. The compensation device includes an air conveyor, the first compensation opening and a second compensation opening, in which the first compensation opening and the second compensation opening open into the oven on opposing sides of a central plane (M) of the oven in the vertical and drawing directions (H, R). The air conveyor is located in terms of flow between the first compensation opening and the second compensation opening, in which the compensation device is configured to remove a volume of air from the oven through one of the compensation openings and to feed the removed volume of air into the oven through the other one of the compensation openings.

A stretching unit for stretching a film is disclosed having an oven and a compensation device. The compensation device includes an air conveyor, the first compensation opening and a second compensation opening, in which the first compensation opening and the second compensation opening open into the oven on opposing sides of a central plane (M) of the oven in the vertical and drawing directions (H, R). The air conveyor is located in terms of flow between the first compensation opening and the second compensation opening, in which the compensation device is configured to remove a volume of air from the oven through one of the compensation openings and to feed the removed volume of air into the oven through the other one of the compensation openings.