Toner, developer, image forming apparatus, and image forming method
A toner includes a binder resin including a copolymer resin containing structural units derived from crystalline and non-crystalline resins, respectively. Spin-spin relaxation time (t50) of the toner at 50° C. measured by pulse NMR is ≦0.05 msec., spin-spin relaxation time (t130) at 130° C. when warmed from 50° C. to 130° C. is >15 msec., and spin-spin relaxation time (t′70) at 70° C. when cooled from 130° C. to 70° C. is ≦1.00 msec. A binarized image obtained by binarizing a phase image of the toner observed by a tapping mode AFM based on intermediate value between maximum and minimum phase difference values in the phase image includes first phase difference images constituted by large phase-difference portions and a second phase difference image constituted by a small phase-difference portion. The first phase difference images are dispersed in the second phase difference image. The dispersion diameter of the first phase difference images is 150 nm or less.
1. A toner, comprising:
a binder resin, comprising
a copolymer resin comprising a structural unit derived from a crystalline polyester resin and a structural unit derived from a non-crystalline polyester resin, such that a molar ratio of a crystalline segment to a non-crystalline segment in the copolymer resin is from 10/90 to 40/60, where the crystalline segment comprises the structural unit derived from the crystalline polyester resin and the non-crystalline segment comprises the structural unit derived from the non-crystalline polyester resin,
wherein a spin-spin relaxation time (t50) of the toner at 50° C. measured by pulse NMR is 0.05 msec or shorter, a spin-spin relaxation time (t130) of the toner at 130° C. when warmed from 50° C. to 130° C. is 15 msec or longer, and a spin-spin relaxation time (t′70) of the toner at 70° C. when cooled from 130° C. to 70° C. is 1.00 msec or shorter, and
a binarized image of the toner, which is obtained by binarizing a phase image of the toner observed by a tapping mode AFM based on an intermediate value between a maximum value and a minimum value of phase difference in the phase image, includes first phase difference images constituted by portions having a large phase difference, and a second phase difference image constituted by a portion having a small phase difference, such that the first phase difference images are dispersed in the second phase difference image, and that a dispersion diameter of the first phase difference images is 150 nm or less.
2. The toner according to claim 1 , wherein:
the crystalline polyester resin comprises a dihydric aliphatic alcohol component and a divalent aliphatic carboxylic acid component as constituent components; and
the non-crystalline polyester resin comprises a dihydric aliphatic alcohol component and a polyvalent aromatic carboxylic acid component as constituent components.
3. The toner according to claim 1 , wherein the first phase difference images have a dispersion diameter of from 10 nm to 100 nm.
4. The toner according to claim 1 , wherein the copolymer resin is produced by reacting the crystalline polyester resin, the non-crystalline polyester resin, and an elongating agent comprising two or more of an isocyanate group, an epoxy group, and a carbodiimide group.
5. The toner according to claim 1 , wherein the binder resin further comprises a second crystalline resin.
6. A developer, comprising:
the toner of claim 1 .
7. An image forming apparatus, comprising:
an electrostatic latent image bearing member;
an electrostatic latent image forming unit configured to form an electrostatic latent image on the electrostatic latent image bearing member; and
a developing unit comprising the toner of claim 1 , and is configured to develop the electrostatic latent image formed on the electrostatic latent image bearing member to form a visible image.
8. An image forming method, comprising:
developing an electrostatic latent image formed on an electrostatic latent image bearing member with the toner of claim 1 to form a visible image;
transferring the visible image to a recording medium; and
fixing the visible image transferred to the recording medium thereon.