Image forming apparatus with fixing via rotary heater and bonding via heater configured to move in thickness direction

An image forming apparatus comprising:

• an electrophotographic image forming portion including (1) a scanner configured to emit light, (2) a plurality of process cartridges including a first process cartridge containing powder adhesive and one or more second process cartridges containing printing toner, and (3) a transfer unit including a transfer belt and a transfer roller, the electrophotographic image forming portion being configured to form an image on a sheet by using the printing toner and apply the powder adhesive onto the sheet;
• a fixing device including (1) a tubular fixing film configured to rotate, (2) a fixing heater disposed in an internal space of the tubular fixing film and configured to be in contact with an inner surface of the tubular fixing film and to heat the tubular fixing film, and (3) a pressing roller that is configured to form a nip portion between the tubular fixing film and the pressing roller, the fixing device being configured to perform a fixing process in which the fixing device fixes the image and the powder adhesive to the sheet by heating and pressing the sheet while nipping and conveying the sheet in the nip portion;
• a stacker on which a plurality of sheets that have passed through the fixing device are stacked;
• a longitudinal-alignment reference plate;
• a semicircular roller configured to move each of the plurality of sheets toward the longitudinal-alignment reference plate, to align the plurality of sheets stacked on the stacker in a longitudinal direction;
• a lateral-alignment jogger configured to move in a lateral direction to align the plurality of sheets stacked on the stacker in the lateral direction, the lateral direction being orthogonal to the longitudinal direction;
• and
• a bonding device configured to perform a bonding process in which the bonding device bonds the plurality of sheets to each other with the powder adhesive, the bonding device including (1) a heating plate configured to move in a thickness direction of the plurality of sheets stacked on the stacker, (2) a pressing plate configured to face the heating plate in the thickness direction and support end portions of the plurality of sheets stacked on the stacker, (3) a bonding heater disposed on an opposite side from the pressing plate with respect to the heating plate in the thickness direction and arranged in contact with the heating plate, and (4) a pressing lever configured to move the bonding heater and the heating plate toward the pressing plate in the thickness direction,
• wherein the heating plate is configured to be brought into contact with one of the plurality of sheets in the bonding process,
• wherein the heating plate has a plate shape elongated in the longitudinal direction and includes a single protruding portion protruding in the thickness direction and elongated in the longitudinal direction,
• wherein, when viewed in the longitudinal direction, the protruding portion includes a flat portion and curved portions formed on both sides of the flat portion,
• wherein a pressed region, in which the sheet is pressed by the heating plate in the bonding process, is elongated in the longitudinal direction and has a width in the lateral direction that is greater than a width of the flat portion and that is less than a width of the nip portion of the fixing device in a sheet conveyance direction at the nip portion,
• wherein a width of an application region onto which the powder adhesive is applied is greater than the width of the pressed region when viewed in the longitudinal direction,
• wherein the powder adhesive is applied in an amount of 0.55 mg/cm2,
• wherein P1 is equal to or higher than 0.1 MPa and equal to or lower than 0.2 MPa, P2 is equal to or higher than 0.3 MPa and equal to or lower than 0.4 MPa, and P1<P2 is satisfied, where P1 (MPa) is a peak value of pressure received by the sheet in the fixing process, and P2 (MPa) is a peak value of pressure received by the sheet in the bonding process,
• wherein a total pressure applied to the sheet from the heating plate in the bonding process is larger than a total pressure applied to the sheet in the nip portion between the tubular fixing film and the pressing roller in the fixing process, and
• wherein a surface temperature of the tubular fixing film in the fixing process is lower than a surface temperature of the heating plate in the bonding process, and the surface temperature of the heating plate in the bonding process is equal to or lower than 200° C.