Toner
The toner has a toner particle in which a toner core containing a binder resin is coated with a shell layer, wherein the binder resin contains a polymer A that has a first monomer unit and a second monomer unit; the first unit is derived from (meth)acrylate ester having an alkyl group having 18 to 36 carbon atoms; the content of the first monomer unit in the polymer is 5.0 to 60.0 mol %; the content of the second monomer unit is 20.0 to 95.0 mol %; the following formula (1) is satisfied when the SP value of the first unit is denoted by SP 11 and the SP value of the second unit is denoted by SP 21 ; and the toner core is coated with a highly uniform shell over at least 90% of the circumference of the toner cross section; 3.00≤( SP 21 −SP 11 )≤25.00 (1).
1. A toner, comprising a toner particle which comprises a toner core containing a binder resin, and a shell layer;
the binder resin containing a polymer A obtained by polymerization of a composition containing a first polymerizable monomer and a second polymerizable monomer that is different from the first polymerizable monomer, the first polymerizable monomer being at least one selected from the group consisting of (meth)acrylate esters having an alkyl group having 18 to 36 carbon atoms and the second polymerizable monomer being at least one selected from the group consisting of formulae (A) and (B)
where X represents a single bond or an alkylene group having 1 to 6 carbon atoms,
R 1 is a nitrile group (—C≡N), amide group (—C(═O)NHR 10 (R 10 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms)), hydroxy group, —COOR 11 (R 11 is an alkyl group having 1 to 6 carbon atoms or a hydroxyalkyl group having 1 to 6 carbon atoms), urethane group (—NHCOOR 12 (R 12 is an alkyl group having 1 to 4 carbon atoms)), urea group (—NH—C(═O)—N(R 13 ) 2 (R 13 independently is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms)), —COO(CH 2 ) 2 NHCOOR 14 (R 14 is an alkyl group having 1 to 4 carbon atoms), or —COO(CH 2 ) 2 —NH—C(═O)—N(R 15 ) 2 (R 15 independently is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms),
R 2 is an alkyl group having 1 to 4 carbon atoms, and
R 3 is a hydrogen atom or methyl group; and
the shell layer comprising at least one amorphous resin selected from the group consisting of homopolymers, alternating copolymers, and random copolymers, the amorphous resin being at least one selected from the group consisting of polyester resins, polyurethane resins, melamine resins, vinyl resins, and urea resins, wherein
the content of the first polymerizable monomer in the composition is 5.0 to 60.0 mol % with reference to the total number of moles of all the polymerizable monomer in the composition,
the content of the second polymerizable monomer in the composition is 20.0 to 95.0 mol % with reference to the total number of moles of all the polymerizable monomer in the composition,
0.60≤(SP 22 −SP 12 )≤15.00 where SP 12 (J/cm 3 ) 0.5 is the SP value of the first polymerizable monomer and SP 22 (J/cm 3 ) 0.5 is the SP value of the second polymerizable monomer,
the shell layer is observed over at least 90% of the circumference of the toner cross section in an image of the toner cross section observed with a transmission electron microscope (TEM), and
SP S1 −SP S2 ≤3.0 is satisfied when the shell layer comprises at least two amorphous resins, where the resin having the highest SP value of the resins comprising the shell layer is resin S1 and has the SP value SP S1 (J/cm 3 ) 0.5 , and the resin having the lowest SP value of the resins comprising the shell layer is resin S2 and has the SP value SP S2 (J/cm 3 ) 0.5 .
2. The toner according to claim 1 , wherein the content of the second polymerizable monomer in the composition is 40.0 to 95.0 mol % with reference to the total number of moles of all the polymerizable monomer in the composition.
3. The toner according to claim 1 , wherein the first polymerizable monomer is at least one selected from the group consisting of (meth)acrylate esters having a linear alkyl group having 18 to 36 carbon atoms.
4. The toner according to claim 1 , wherein the acid value of the polymer A is not more than 30 mg KOH/g.
5. The toner according to claim 1 , wherein
R 1 is said nitrile group (—C≡N), amide group (—C(═O)NHR 10 ), hydroxy group, —COOR 11 , —COO(CH 2 ) 2 NHCOOR 14 , or —COO(CH 2 ) 2 —NH—C(═O)—N(R 15 ) 2 .
6. The toner according to claim 1 , wherein the composition further comprises a third polymerizable monomer that is different from both the first and second polymerizable monomers, and
the third polymerizable monomer is at least one polymerizable monomer selected from the group consisting of styrene, methyl methacrylate, and methyl acrylate.
7. The toner according to claim 1 , wherein the endothermic quantity for the endothermic peak associated with the melting of the polymer A is 20 to 100 (J/g) when the toner is subjected to measurement by differential scanning calorimetry.
8. The toner according to claim 1 , wherein the charge decay constant of the polymer A is not more than 100.
9. The toner according to claim 1 , wherein the shell layer is constituted of one species of amorphous resin.
10. The toner according to claim 1 , wherein the thickness of the shell layer is 2 to 100 nm in an image of the toner cross section observed with a transmission electron microscope (TEM).
11. The toner according to claim 1 , wherein polymer A is a vinyl polymer.
12. The toner according to claim 1 , wherein the acid value of polymer A is not more than 30 mg KOH/g.
13. The toner according to claim 1 , wherein the toner contains a wax, and
0.2×A≤W≤A when W mass parts is the content of the wax, A mass parts is the content of the first monomer unit, and the content of the polymer A in the toner is 100 mass parts.