Electrostatic latent image developing toner
An electrostatic latent image developing toner includes toner particles each including a toner core and a shell layer. The shell layer contains a resin including a unit derived from a monomer of a thermosetting resin and a unit derived from a thermoplastic resin. The thermosetting resin is one or more resins selected from the group of amino resins consisting of a melamine resin, a urea resin, and a glyoxal resin. When heat and pressure are applied to a toner layer formed on a polyester film under conditions of a temperature of 140° C. and a pressure of 7 MPa so that the toner particles are not superimposed, the toner particles of the toner layer are broken in a manner that a melt of a component of the toner core flows out from a plurality of points in an outer surface of the shell layer.
1. An electrostatic latent image developing toner comprising:
toner particles each including a toner core containing a binder resin, and a shell layer coating a surface of the toner core,
wherein the shell layer contains an acrylamide polymer crosslinked with methylol melamine,
the shell layer has a thickness of 1 nm or more and 20 nm or less, and
when toner characteristics are evaluated through a test in which heat and pressure are applied to a toner layer formed on a polyester film under conditions of a temperature of 140° C. and a pressure of 7 MPa so that the toner particles are not superimposed, the toner particles of the toner layer are broken in a manner that a melt of a component of the toner core flows out from a plurality of points in an outer surface of the shell layer.
2. An electrostatic latent image developing toner according to claim 1 , wherein
a zeta potential, measured in an aqueous medium adjusted to pH 4, of the toner core is negative.
3. An electrostatic latent image developing toner according to claim 1 , wherein
when toner characteristics are evaluated through an alkaline treatment that involves:
obtaining a dispersion by dispersing 10 g of the toner in 50 mL of a basic aqueous solution of pH 10 containing an anion surfactant;
allowing the obtained dispersion to stand still at a temperature of 50° C. for 10 hours; and
drying a solid content separated from the standing dispersion,
a rate Sx of change in specific surface area obtained in accordance with an equation Sx=100×(Sb−Sa)/Sa is 35% or more,
where Sb is a specific surface of the toner subjected to the alkaline treatment, and
Sa is a specific surface of the toner not subjected to the alkaline treatment.
4. An electrostatic latent image developing toner according to claim 1 , wherein
a colorant or a mold releasing agent is present in the vicinity of the surface of the toner core.
5. An electrostatic latent image developing toner according to claim 1 , wherein
the toner core contains a polyester resin as the binder resin.
6. An electrostatic latent image developing toner according to claim 5 , wherein
the polyester resin has a number average molecular weight of 1,100 or more and 2,000 or less, and
a ratio of a mass average molecular weight of the polyester resin relative to the number average molecular weight of the polyester resin is 9 or more and 21 or less.