IMAGE FORMING APPARATUS AND IMAGE FORMING METHOD

摘要

An image forming apparatus includes a developing unit that stores a developer containing a toner and develops an electrostatic charge image on a image holding member by the developer to form a toner image, a transfer unit that transfers the toner image on the image holding member onto a recording medium, and a fixing unit that performs an operation of heating and pressing twice or more to the toner image on the recording medium by at least one heating and pressing member which contacts with the toner image, wherein the toner has a sea and island structure of a sea portion containing a binder resin and an island portion containing a release agent, a maximum frequent value and a skewness in distribution of eccentricity B of the island portion is 0.75 to 0.95 and −1.10 to −0.50, respectively, and eccentricity B is defined in the specification.

主权项

1. An image forming apparatus comprising:
an image holding member; a charging unit that charges a surface of the image holding member; an electrostatic charge image forming unit that forms an electrostatic charge image on a charged surface of the image holding member; a developing unit that stores a developer containing a toner and develops the electrostatic charge image formed on a surface of the image holding member by using the developer so as to form a toner image; a transfer unit that transfers the toner image formed on the surface of the image holding member onto a surface of a recording medium; and a fixing unit that performs an operation of heating and pressing to the toner image on the recording medium twice or more by using one or more of a heating and pressing member which contacts with the toner image, wherein the toner contains a binder resin, a colorant, and a release agent, and has a sea and island structure of a sea portion containing the binder resin and an island portion containing the release agent, a maximum frequent value in distribution of an eccentricity B of the island portion containing the release agent is in a range of from 0.75 to 0.95, and a skewness in the distribution of the eccentricity B is in a range of from −1.10 to −0.50, the eccentricity B being represented by the following expression (1):
Eccentricity B=2d/D  (1) wherein D indicates an equivalent circle diameter (μm) of the toner in an observation of a cross-section of the toner, and d indicates a distance (μm) from the centroid of the toner to the centroid of the island portion containing the release agent in the observation of a cross-section of the toner.