Toner and method for producing toner
A toner comprising: a toner particle that includes a binder resin, and an external additive, wherein the toner particle includes a polyester resin on the surface; the toner particle includes a polyvalent metal element; where an electrical resistivity of the polyvalent metal element at 20° C. is denoted by A Ω·m, and an amount of the polyvalent metal element in the toner particle is denoted by B μmol/g, a following relationship is satisfied: 0.025×10 8 ≤(1/ A )× B ≤4.500×10 8 ; the external additive includes silica particles; and the silica particles includes spherical silica particles having a number average particle diameter of from 20 nm to 40 nm.
1. A toner, comprising:
a toner particle comprising a binder resin and a polyvalent metal element;
an external additive comprising a spherical silica particle having a number average particle diameter of 20-40 nm and a circularity of 0.80 or more; and
a surface of the toner particle comprising a polyester resin, wherein
0.025×10 8 ≤(1/A)×B≤4.500×10 8 where A (Ω·m) is an electrical resistivity of the polyvalent metal element at 20° C., and B (μmol/g) is an amount of the polyvalent metal element in the toner particle.
2. The toner according to claim 1 , wherein the polyvalent metal element is at least one member selected from the group consisting of aluminum, iron, magnesium and calcium.
3. The toner according to claim 2 , wherein when the polyvalent metal element includes aluminum, the amount of aluminum in the toner particle is 0.080 to 0.400 μmol/g,
when the polyvalent metal element includes iron, the amount of iron in the toner particle is 0.270 to 1.250 μmol/g,
when the polyvalent metal element includes magnesium, the amount of magnesium in the toner particle is 2.000 to 20.000 μmol/g, and
when the polyvalent metal element includes calcium, the amount of calcium in the toner particle is 1.500 to 15.000 μmol/g.
4. The toner according to claim 1 , wherein a weight average molecular weight Mw of the polyester resin is 10000 to 60000; and
a concentration of ester groups in the polyester resin is 20 to 50% by mass.
5. The toner according to claim 1 , wherein the spherical silica particle is a sol-gel silica particle.
6. The toner according to claim 1 , wherein the toner particle includes wax, and
As is 5 to 40%, where As is a ratio of an area occupied by the wax in a region from the toner particle surface to a depth of 1.0 μm in cross-sectional observation of the toner using a transmission electron microscope.
7. The toner according to claim 1 , wherein the toner particle is an emulsion aggregation toner particle.
8. The toner according to claim 1 , wherein the binder resin is a polyester resin.
9. A method for producing the toner according to claim 1 , the method comprising the steps of:
aggregating fine particles of the binder resin to form aggregated particles; and
fusing the aggregated particles to obtain the toner particle.