Toner and method of producing toner
A toner includes a toner particle containing a binder resin and a release agent. The binder resin contains an amorphous resin and a crystalline resin, and a content of the crystalline resin is 1.0 to 20.0% by mass based on a mass of the binder resin. In a cross-section of the toner particle observed by scanning transmission electron microscopy, (i) there exists a matrix A of the amorphous resin with domains A of the release agent dispersed therein, (ii) domains A each include a matrix B of the release agent having domains B of the crystalline resin dispersed therein, and (iii) domains A each being covered with the crystalline resin having an average coverage of the domains A by the crystalline resin of 70% or more.
1 . A toner, comprising:
a toner particle containing a binder resin and a release agent;
the binder resin comprising an amorphous resin and a crystalline resin, a content of the crystalline resin being 1.0 to 20.0% by mass based on a mass of the binder resin; and
in a cross-section of the toner particle observed by scanning transmission electron microscopy
(i) there exists a matrix A of the amorphous resin with domains A of the release agent dispersed therein,
(ii) domains A each include a matrix B of the release agent with domains B of the crystalline resin dispersed therein, and
(iii) the domains A are each covered with the crystalline resin, and an average coverage of the domains A by the crystalline resin is at least 70%, wherein
a melting point difference obtained by subtracting a melting point of the release agent from a melting point of the crystalline resin is 0 to 10° C., and
a heat-melted crystalline resin composition obtained by separation operation of an N,N-dimethylformamide soluble fraction of the toner particle by a solvent gradient elution method has a visible light transmittance per 1 mm optical path length of at least 90%, the crystalline resin composition comprising a portion constituting domain B and a portion covering domain A.
2 . The toner according to claim 1 , wherein there exists an endothermic peak derived from the crystalline resin in a temperature-endothermic curve measured using a differential scanning calorimeter (DSC) at a rate of temperature rise and a rate of temperature fall of both 10° C./min, and tw2>tw1, where tw1 is a half width [° C.] of the endothermic peak derived from the crystalline resin in a first temperature rise process, and tw2 is a half width [° C.] of the endothermic peak derived from the crystalline resin in a second temperature rise process.
3 . The toner according to claim 2 , wherein tw2/tw1≥1.20.
4 . The toner according to claim 1 , wherein SPc−SPw≤5.11 when SPc and SPw are respectively SP values [(J/cm 3 ) 0.5 ] of the crystalline resin and the release agent.
5 . The toner according to claim 1 , wherein an average area ratio of the crystalline resin in the domains A of the release agent observed by scanning transmission electron microscopy is 10 to 50%.
6 . The toner according to claim 1 , wherein a content of the crystalline resin based on the binder resin is 5.0 to 15.0% by mass.
7 . The toner according to claim 4 , wherein the binder resin contains amorphous resins A1, A2 and A3, and
2.05≤ SP 1− SPc≤ 2.86
0.20≤ SP 2− SP 1≤0.61
0.20≤ SP 3− SP 2≤0.61
when SP1, SP2 and SP3 are respectively SP values [(J/cm 3 ) 0.5 ] of A1, A2, and A3.
8 . The toner according to claim 1 , wherein both the amorphous resin and the crystalline resin are polyester resins.
9 . The toner according to claim 1 , wherein the release agent is a hydrocarbon wax.
10 . A method of producing a toner that contains a toner particle containing a binder resin and a release agent, the binder resin comprising an amorphous resin and a crystalline resin, a content of the crystalline resin being 1.0 to 20.0% by mass based on a mass of the binder resin, the method comprising the steps of:
melt-kneading a material containing the amorphous resin, the crystalline resin and the release agent to obtain a melt-kneaded product; and
pulverizing the melt-kneaded product to obtain powder, wherein
in a cross-section of the toner particle observed by scanning transmission electron microscopy
(i) there exists a matrix A of the amorphous resin with domains A of the release agent dispersed therein,
(ii) domains A each include a matrix B of the release agent with domains B of the crystalline resin dispersed therein, and
(iii) the domains A are each covered with the crystalline resin, and an average coverage of the domains A by the crystalline resin is at least 70%, and
a melting point difference obtained by subtracting a melting point of the release agent from a melting point of the crystalline resin is 0 to 10° C., and
a heat-melted crystalline resin composition obtained by separation operation of an N,N-dimethylformamide soluble fraction of the toner particle by a solvent gradient elution method has a visible light transmittance per 1 mm optical path length of at least 90%, the crystalline resin composition comprising a portion constituting domain B and a portion covering domain A.