Search

EP-4435520-B1 - ELECTROSTATIC IMAGE DEVELOPING TONER

EP4435520B1EP 4435520 B1EP4435520 B1EP 4435520B1EP-4435520-B1

Inventors

  • ISHIZUKA, DAISUKE
  • FURUTA, TSUTOMU
  • SAITO, ERINA
  • NAKAJIMA, TOMOHITO

Dates

Publication Date
20260506
Application Date
20230829

Claims (13)

  1. An electrostatic image developing toner comprising: a binder resin which is an amorphous polyester resin and a crystalline polyester resin; and resin particles that are crosslinked styrene-(meth)acrylate copolymer, wherein the styrene-(meth)acrylate copolymer is obtained by polymerization of a monomer-containing liquid including styrene and (meth)acrylate, wherein, when a glass transition temperature calculated using a Fox equation on the basis of proportions of monomers constituting the entire resin particles is defined as Tg(C1)°C and a glass transition temperature measured using a differential scanning calorimeter is defined as Tg(E)°C, as determined following the method given in the description, 5.0 ≤ Tg E − Tg C 1 ≤ 20.0 , and when a glass transition temperature calculated using a Fox equation on the basis of monomer proportions determined by surface analysis of the resin particles, as determined following the method given in the description, is defined as Tg(C2)°C, Tg C 1 < Tg C 2 .
  2. An electrostatic image developing toner comprising: a binder resin which is an amorphous polyester resin and a crystalline polyester resin; and resin particles that are crosslinked styrene-(meth)acrylate copolymer, wherein the styrene-(meth)acrylate copolymer is obtained by polymerization of a monomer-containing liquid including styrene and (meth)acrylate, wherein, when a proportion of a unit derived from a styrene monomer included in the resin particles is defined as Ws(B) mol% and a proportion of the unit derived from a styrene monomer, the proportion being determined by surface analysis of the resin particles, as determined following the method given in the description, is defined as Ws(S) mol%, Ws(S) is 40 mol% or more and 80 mol% or less, and 2 ≤ Ws S − Ws B ≤ 20 .
  3. The electrostatic image developing toner according to claim 1 or 2, wherein the Tg(E) is 0°C or more and 30°C or less.
  4. The electrostatic image developing toner according to any one of claims 1 to 3, wherein, in production of the resin particles, a ratio of a content of the styrene in the monomer-containing liquid to a content of the (meth)acrylate in the monomer-containing liquid is increased with progress of polymerization.
  5. The electrostatic image developing toner according to any one of claims 1 to 4, wherein a proportion of the crystalline resin in the binder resin is 15% by mass or more and 40% by mass or less.
  6. The electrostatic image developing toner according to any one of claims 1 to 5, wherein a content of the resin particles is 2% by mass or more and 20% by mass or less.
  7. The electrostatic image developing toner according to any one of claims 1 to 6, wherein a ratio w1/w2 of a content w1 of the resin particles in the toner to a content w2 of the crystalline resin, as determined following the method given in the description, in the toner is 0.2 or more and 2.0 or less.
  8. The electrostatic image developing toner according to any one of claims 1 to 7, wherein the amorphous polyester resin includes a unit derived from an aliphatic dicarboxylic acid, and a proportion of the unit derived from an aliphatic dicarboxylic acid to a unit derived from an acid component monomer included in the amorphous polyester resin is 2 mol% or more and 20 mol% or less.
  9. The electrostatic image developing toner according to any one of claims 1 to 8, wherein an acid value of the amorphous polyester resin is 5 mgKOH/g or more and 20 mgKOH/g or less.
  10. The electrostatic image developing toner according to any one of claims 1 to 9, wherein, when a glass transition temperature of the amorphous polyester resin, the glass transition temperature being measured using a differential scanning calorimeter, is defined as Tg(ap)°C, 40 ≤ Tg ap − Tg C 1 ≤ 90 .
  11. The electrostatic image developing toner according to any one of claims 1 to 10, wherein, when an SP value of the binder resin, the SP value being calculated by a Fedors method, is defined as SP(1) and an SP value calculated using a Fedors method on the basis of a monomer composition determined by surface analysis of the resin particles is defined as SP(2), as determined following the method given in the description, SP 1 − SP 2 ≥ 0.15 .
  12. The electrostatic image developing toner according to any one of claims 1 to 11, wherein an average equivalent circle diameter of domains formed by the resin particles, as determined following the method given in the description, is 50 nm or more and 300 nm or less.
  13. The electrostatic image developing toner according to any one of claims 1 to 12, wherein an average shape factor SF-1 of domains formed by the resin particle, as determined following the method given in the description, s is 130 or less.

Description

Background (i) Technical Field The present disclosure relates to an electrostatic image developing toner. (ii) Related Art Japanese Unexamined Patent Application Publication No. 2011-34013 discloses a toner that includes a binder resin having a first functional group, organic microparticles having a second functional group present on the surfaces, and a colorant, wherein the first and second functional groups are crosslinked with each other, the organic microparticles have a crosslinked structure formed as a result of resins constituting the organic microparticles crosslinking with one another, and the designed glass transition temperature is 20°C or less. Japanese Unexamined Patent Application Publication No. 2021-189408 discloses an electrostatic image developing toner that includes toner matrix particles including at least a binder resin, wherein the toner matrix particles are formed as a result of aggregation and fusion of microparticles of the binder resin and seeded-polymerized microparticles, each of the seeded-polymerized microparticles has a shell and a seed portion, the difference (Tg2 - Tg1) between the glass transition temperature Tg1 of the seed portion and the glass transition temperature Tg2 of the shell is 50°C or more, the binder resin includes an amorphous resin having a glass transition temperature Tgm as a principal component, and the Tgm is higher than Tg1. Summary It is known that the low temperature fixability of a toner can be enhanced by adding a crystalline resin to the toner. In the case where a toner including a large amount of crystalline resin is used, when images are stacked on top of one another after the fixing step has been finished and before the sheet temperature is reduced, the images may adhere to one another to cause image defects. Although a technique in which an additive such as resin particles is added to the inside of toner particles is also known, it has been difficult to reduce the adhesion of images, such as offset, and achieve low temperature fixability simultaneously. Accordingly, it is an object of the present disclosure to provide a toner that may reduce the adhesion of images to one another and has low temperature fixability simultaneously, compared with a toner including resin particles wherein a component derived from a styrene monomer is not localized in the surfaces of the particles. According to a first aspect of the present invention as given in claim 1, there is provided an electrostatic image developing toner including a binder resin which is an amorphous polyester resin and a crystalline polyester resin and resin particles that are crosslinked styrene-(meth)acrylate copolymer, wherein the styrene-(meth)acrylate copolymer is obtained by polymerization of a monomer-containing liquid including styrene and (meth)acrylate, wherein, when a glass transition temperature calculated using a Fox equation on the basis of proportions of monomers constituting the entire resin particles is defined as Tg(C1)°C and a glass transition temperature measured using a differential scanning calorimeter is defined as Tg(E)°C, 5.0 ≤ Tg(E) - Tg(C1) ≤ 20.0 and, when a glass transition temperature calculated using a Fox equation on the basis of monomer proportions determined by surface analysis of the resin particles is defined as Tg(C2)°C, Tg(C1) < Tg(C2). According to a second aspect of the present invention as given in claim 2, there is provided an electrostatic image developing toner including a binder resin which is an amorphous polyester resin and a crystalline polyester resin and resin particles that are crosslinked styrene-(meth)acrylate copolymer, wherein the styrene-(meth)acrylate copolymer is obtained by polymerization of a monomer-containing liquid including styrene and (meth)acrylate, wherein, when a proportion of a unit derived from a styrene monomer included in the resin particles is defined as Ws(B) mol% and a proportion of the unit derived from a styrene monomer, the proportion being determined by surface analysis of the resin particles, is defined as Ws(S) mol%, Ws(S) is 40 mol% or more and 80 mol% or less, and 2 ≤ Ws(S) - Ws(B) ≤ 20. Brief Description of the Drawings Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein: Fig. 1 is a schematic diagram illustrating an example of an image forming apparatus according to an exemplary embodiment; andFig. 2 is a schematic diagram illustrating an example of a process cartridge detachably attachable to the image forming apparatus according to the exemplary embodiment. Detailed Description Exemplary embodiments of the present disclosure are described below. It should be noted that the following description, Examples, etc. are intended to be illustrative of the exemplary embodiments but not restrictive of the scope of the present disclosure. In the present disclosure, the expressions "X or more and Y or less" and "X to Y" used for describing a numerical rang