Toner and developer
A toner including: a binder resin component; crystal nucleating agent; releasing agent; and colorant, wherein the binder resin component contains a crystalline polyester resin and a non-crystalline polyester resin, the crystal nucleating agent is at least one of an aliphatic ester compound and an aliphatic amide compound each having a melting point of 60° C. or higher but lower than 150° C., and wherein the toner satisfies Expressions (I) and (II): Tc>Tp +10 Expression (I) Tm>Tp +2 Expression (II) where Tp denotes lowest exothermic peak temperature [° C.] in 0° C. to 200° C. in DSC curve obtained DSC of the crystalline polyester resin, Tc denotes lowest exothermic peak temperature [° C.] in 0° C. to 200° C. in DSC curve obtained DSC of the crystal nucleating agent, and Tm denotes lowest exothermic peak temperature [° C.] in 0° C. to 200° C. in DSC curve through DSC of the mixture of the crystalline polyester resin and the crystal nucleating agent.
1. A toner comprising:
a binder resin component;
a crystal nucleating agent;
a releasing agent; and
a colorant,
wherein the binder resin component contains a crystalline polyester resin and a non-crystalline polyester resin, wherein the crystalline polyester resin has a melting point of 60° C. or higher but lower than 80° C.,
wherein the crystal nucleating agent is at least one selected from the group consisting of an aliphatic ester compound having a melting point of 60° C. or higher but lower than 120° C. and an aliphatic amide compound having a melting point of 60° C. or higher but lower than 120° C., and
wherein the toner satisfies the following expressions (I) and (II):
Tc>Tp+ 10 Expression (I)
Tm>Tp+ 2 Expression (II)
where Tp denotes the lowest exothermic peak temperature [° C.] in a range of 0° C. to 200° C. in a differential scanning calorimetry (DSC) curve obtained through DSC of the crystalline polyester resin, Tc denotes the lowest exothermic peak temperature [° C.] in a range of 0° C. to 200° C. in a DSC curve obtained through DSC of the crystal nucleating agent, and Tm denotes the lowest exothermic peak temperature [° C.] in a range of 0° C. to 200° C. in a DSC curve obtained through DSC of the mixture of the crystalline polyester resin and the crystal nucleating agent,
wherein the toner is obtained by a method comprising:
dispersing, in an aqueous medium, an oil phase containing the binder resin component, the crystal nucleating agent, the releasing agent and the colorant in an organic solvent, to prepare a dispersion liquid; and removing the organic solvent from the dispersion liquid.
2. The toner according to claim 1 , wherein the toner satisfies the following expressions (I) and (II′):
Tc>Tp+ 10 Expression (I)
Tm>Tp+ 5 Expression (II′).
3. The toner according to claim 1 , wherein the crystal nucleating agent is the aliphatic amide compound having a melting point of 60° C. or higher but lower than 120° C.
4. The toner according to claim 1 , wherein a solubility at 70° C. of the crystal nucleating agent to the organic solvent is 5% by mass or more and a solubility at 25° C. of the crystal nucleating agent to the organic solvent is 0.5% by mass or less.
5. The toner according to claim 1 , wherein the melting point of the crystal nucleating agent is 70° C. or higher but lower than 120° C.
6. The toner according to claim 1 , wherein the crystalline polyester resin has a constituent unit derived from a saturated aliphatic dicarboxylic acid and a constituent unit derived from a saturated aliphatic diol.
7. The toner according to claim 1 , wherein the toner has a glass transition temperature (Tg1st) of 20° C. or higher but lower than 60° C., where the glass transition temperature (Tg1st) is measured at the first temperature raising in DSC.
8. The toner according to claim 1 , wherein the toner has a glass transition temperature (Tg2nd) of 10° C. or higher but lower than 30° C., where the glass transition temperature (Tg2nd) is measured at the second temperature raising in DSC.
9. The toner according to claim 1 , wherein soluble matter of the crystalline polyester resin in o-dichlorobenzene has a weight average molecular weight (Mw) of 3,000 to 30,000, a number average molecular weight (Mn) of 1,000 to 10,000, and a ratio Mw/Mn of 1.0 to 10, where the weight average molecular weight (Mw) and the number average molecular weight (Mn) are measured through gel permeation chromatography (GPC).
10. The toner according to claim 1 , wherein the method for obtaining the toner comprises:
preparing the oil phase by dissolving or dispersing, in an organic solvent, an active hydrogen group-containing compound serving as a precursor of the binder resin component, a polymer containing a site reactive with the active hydrogen group-containing compound serving as another precursor of the binder resin component, the crystalline polyester resin, the non-crystalline polyester resin, the crystal nucleating agent, the releasing agent and the colorant;
dispersing the oil phase in the aqueous medium to prepare the dispersion liquid and allowing, in the dispersion liquid, the active hydrogen group-containing compound and the polymer containing a site reactive with the active hydrogen group-containing compound to undergo crosslinking reaction or elongating reaction or both of the crosslinking reaction and the elongating reaction; and
removing the organic solvent from the dispersion liquid.
11. A developer comprising:
the toner as claimed in claim 1 .
12. The developer as claimed in claim 11 , wherein the developer further comprises a carrier.