Toner for developing electrostatic image and method of manufacturing the same
A toner for developing an electrostatic image and a method of manufacturing the same are provided. The toner may have a morphological surface characteristic that induces high thermal and physical characteristics. The toner may simultaneously improve gloss, charge stability, anti-cohesiveness, storage ability, and low temperature fixability.
1. A toner for developing an electrostatic image, the toner comprising:
toner particles including:
a crystalline polyester resin having a melting temperature in a range of from 60° C. to 75° C.;
an amorphous polyester resin;
a releasing agent comprising a mixture of an ester wax and a non-ester wax with a content weight percentage of the ester wax being within a range of 1% to 35% of a total weight of the non-ester wax and the ester wax; and
a colorant,
wherein:
the toner particles have a mean volume diameter of 5 to 7 μm,
when 50 of the toner particle are viewed in a plane image obtained by scanning electron microscopy (SEM),
the 50 toner particles collectively project a plurality of surface regions onto the plane image, each of the plurality of surface regions being a region, of the crystalline polyester resin or the releasing agent, that is stainable by RuO 4 and exposed on the surface of one of the 50 toner particles, the plurality of surface regions including at least one region of the crystalline polyester resin,
a total number of the plurality of surface regions projected onto the plane image is in a range of from 6 to 24, and
an area S stain on the plane image occupied by a total surface area of the plurality of surface regions that is stainable by RuO 4 , and a total area S toner on the plane image occupied by the toner particle satisfy −4.3 ≤log(S stain /S toner )≤−2.1,
the toner particles have charge stability based on the crystalline polyester resin having an electrical resistance [Ω] and the amorphous polyester resin having an electrical resistance [Ω], the electrical resistance [Ω] of the crystalline polyester and the electrical resistance [Ω] of the amorphous polyester resin satisfy:
3.88≤ R crystalline /R amorphous ≤74.2,
15≤log [R crystalline ]≤20,
where R crystalline is the electrical resistance [Ω] of the crystalline polyester resin and R amorphous is the electrical resistance [Ω] of the amorphous polyester resin, and
compatibility between the amorphous polyester resin and the releasing agent as represented by a solubility parameter of the crystalline polyester resin, a solubility parameter of the amorphous polyester resin, and a solubility parameter of the releasing agent satisfy:
ΔSP α =|SP amorphous −SP crystalline |≥3.11,
ΔSP β =|SP crystalline −SP wax |≤0.49,
ΔSP γ =|SP amorphous −SP wax |≥3.84,
where SP amorphous is the solubility parameter [(J/cm 3 ) 0.5 ] of the amorphous polyester resin, SP crystalline is the solubility parameter [(J/cm 3 ) 0.5 ] of the crystalline polyester resin, and SP wax is the solubility parameter [(J/cm 3 ) 0.5 ] of the releasing agent.