Toner, image-forming apparatus, process cartridge and image forming method

An image-forming apparatus comprising a developing means for moving a toner to an electrostatic latent image formed on a photosensitive member, to render the electrostatic latent image visible to form a toner image, and a transfer means for transferring the toner image to a transfer medium to form an image;

• in a developer-carrying member of said developing means, at least an alternating-current bias being applied to make the toner adhere to the electrostatic latent image to form a visible image;
• and
• said toner comprising a binder resin and a colorant;
• wherein;
• said toner contains as the binder resin at least a vinyl resin selected from the group consisting of:
• a vinyl resin having a carboxyl group and a vinyl resin having an epoxy group;
• a vinyl resin having a carboxyl group and an epoxy group;
• and
• a vinyl resin produced by the reaction of a carboxyl group with an epoxy group;
• and
• said toner has, in its dielectric dissipation factor (tan δ), at least a maximum value and a minimum value in the temperature range of from 20° C. to 150° C., and, where the maximum value is represented by Max and the minimum value by Min, having a value of log10(Max/Min)≦2.

A process cartridge comprising:

• an electrostatic image-bearing member, and developing means for developing an electrostatic image formed on the electrostatic image-bearing member with a toner contained therein;
• the electrostatic image-bearing member and the developing means being integrally assembled to form a process cartridge, which is detachably mountable to a main assembly of the image forming apparatus;
• and
• said toner comprising a binder resin and a colorant;
• wherein;
• said toner contains as the binder resin at least a vinyl resin selected from the group consisting of:
• a vinyl resin having a carboxyl group and a vinyl resin having an epoxy group;
• a vinyl resin having a carboxyl group and an epoxy group;
• and
• a vinyl resin produced by the reaction of a carboxyl group with an epoxy group;
• and
• said toner has, in its dielectric dissipation factor (tan δ), at least a maximum value and a minimum value in the temperature range of from 20° C. to 150° C., and, where the maximum value is represented by Max and the minimum value by Min, having a value of log10(Max/Min)≦2.

An image-forming method comprising subjecting a toner image held on a transfer medium, to heat-and-pressure fixing by a heat-and-pressure fixing means to form a fixed image on the transfer medium, wherein;

• (1) a toner which forms the toner image is a toner comprising a binder resin and a colorant;
• said toner containing as the binder resin at least a vinyl resin selected from the group consisting of:
• a vinyl resin having a carboxyl group and a vinyl resin having an epoxy group;
• a vinyl resin having a carboxyl group and an epoxy group;
• and
• a vinyl resin produced by the reaction of a carboxyl group with an epoxy group;
• and
• said toner having, in its dielectric dissipation factor (tan δ), at least a maximum value and a minimum value in the temperature range of from 20° C. to 150° C., and, where the maximum value is represented by Max and the minimum value by Min, having a value of log10(Max/Min)≦2;
• and
• (2) as said heat-and-pressure fixing means, a heat-and-pressure fixing means is used which has at least;
• (i) a magnetic field generation means;
• (ii) a rotary heating member having at least a heat generation layer capable of generating heat by electromagnetic induction, and a release layer;
• and
• (iii) a rotary pressure member which forms a nip with the heating member;
• and
• said toner image held on said transfer medium is heat and pressure fixed while said rotary pressing member is pressed against said rotary heating member via said transfer medium.