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JP-2026074498-A - Toner and two-component developer

JP2026074498AJP 2026074498 AJP2026074498 AJP 2026074498AJP-2026074498-A

Abstract

[Problem] To provide a toner and a two-component developer that have excellent low-temperature fixing properties, in that they can form an image with excellent bending strength while suppressing the occurrence of low-temperature offset when fixed at low temperatures, and also have sufficient heat resistance for storage. [Solution] The toner has the following configuration in which an external additive is attached to the surface of toner particles. The toner particles contain an amorphous polyester resin, a crystalline polyester resin, a release agent, and a first fatty acid metal salt. The first fatty acid metal salt contains metal ions of trivalent or higher. The average dispersion diameter of the first fatty acid metal salt in the toner particles is 50 nm or more and 500 nm or less. The external additive contains a second fatty acid metal salt. [Selection Diagram] Figure 1

Inventors

  • 和田 統
  • 椿 頼尚

Assignees

  • シャープ株式会社

Dates

Publication Date
20260507
Application Date
20241021

Claims (9)

  1. Toner in which an external additive is attached to the surface of toner particles, The toner particles comprise an amorphous polyester resin, a crystalline polyester resin, a mold release agent, and a first fatty acid metal salt. The aforementioned first fatty acid metal salt is a metal salt with a valent or higher valency. The average dispersion diameter of the first fatty acid metal salt in the toner particles is 50 nm or more and 500 nm or less. The toner is characterized by containing a second fatty acid metal salt as an external additive.
  2. The toner according to claim 1, The toner is characterized in that the surface exposure rate of the first fatty acid metal salt, calculated as the area ratio of the first fatty acid metal salt to the surface of the toner particles, is 1% or more and 5% or less.
  3. The toner according to claim 1 or claim 2, The toner is characterized in that the content of the first fatty acid metal salt in the toner particles is 0.5% by mass or more and 2.0% by mass or less.
  4. The toner according to claim 1 or claim 2, A toner characterized in that, when the content of the crystalline polyester resin in the toner particles is M C mass%, and the content of the first fatty acid metal salt in the toner particles is M TF mass%, the relationship shown in the following formula (1) is satisfied. 2≦M C /M TF ≦10 (1)
  5. The toner according to claim 1 or claim 2, The toner is characterized in that the average particle size of the second fatty acid metal salt is 0.5 μm or more and 1.5 μm or less.
  6. The toner according to claim 1 or claim 2, The toner is characterized in that the content of the second fatty acid metal salt is 0.1 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of the toner particles.
  7. The toner according to claim 1 or claim 2, The toner is characterized in that the adhesion strength of the second fatty acid metal salt to the toner particles is 20% or more.
  8. The toner according to claim 1 or claim 2, The toner is characterized in that the first fatty acid metal salt has a hydroxyl group.
  9. A two-component developer characterized by comprising the toner described in claim 1 or claim 2 and a carrier.

Description

This disclosure relates to toner and two-component developer. Toner used in image forming devices such as photocopiers, multifunction printers, and facsimile machines that utilize electrophotography (toner for electrostatic image development) generally has a structure in which an external additive is attached to the surface of toner particles (toner core). For example, Patent Document 1 discloses a toner having toner particles containing a crystalline polyester resin, an amorphous polyester resin, a higher fatty acid metal salt, and a colorant, wherein the crystalline polyester resin has a crystal nucleating agent site at the end of its molecular chain and is within a predetermined SP value range, the crystal nucleating agent site is a site derived from a predetermined aliphatic monoalcohol and/or aliphatic monocarboxylic acid, the number of carbon atoms in the higher fatty acid metal salt is within a predetermined range, and the higher fatty acid metal salt is a metal salt with a valency of 2 or higher (i.e., the valency of the metal ion is 2 or higher). Japanese Patent Publication No. 2015-118310 This is a schematic cross-sectional view showing a toner according to one embodiment of the present disclosure.This is a schematic cross-sectional view showing the interface between adjacent toner particles during the fixing of toner according to one embodiment of the present disclosure.This diagram shows the procedure for evaluating bending strength when assessing low-temperature fixability.Figure 3 is an enlarged view of the dashed line area, illustrating the case where there is no peeling of the toner layer.Figure 3 is an enlarged view of the dashed line area, illustrating an example where the toner layer is peeling off. The toner and two-component developer described herein will be explained below. In this disclosure, "internal addition" means adding the additive so that it is contained within the material being added, and "external addition" means adding the additive so that it adheres to the outer surface (surface) of the material being added. 1. Overall Toner Configuration The toner according to this embodiment is a toner in which an external additive is attached to the surface of toner particles, and satisfies the following requirements (A) to (D). (A) The toner particles include an amorphous polyester resin, a crystalline polyester resin, a mold release agent, and a first fatty acid metal salt. (B) The first fatty acid metal salt is a metal salt with a valent or higher valency. (C) The average dispersion diameter of the first fatty acid metal salt in the toner particles is 50 nm or more and 500 nm or less. (D) The external additive contains a second fatty acid metal salt. Figure 1 is a schematic cross-sectional view showing a toner 1 according to one embodiment of the present disclosure. Using Figure 1, the toner particles 10 of the toner 1 have a structure in which a crystalline polyester resin 12, a release agent 13, a colorant 14, and a first fatty acid metal salt 15 are dispersed in an amorphous polyester resin 11 as a binder resin. Furthermore, a second fatty acid metal salt 16 is attached to the surface of the toner particles 10. Thus, the first fatty acid metal salt 15 is internally added to the toner particles 10, and the second fatty acid metal salt 16 is externally added to the toner particles 10. The toner 1 may contain other optional components as long as they do not impair the effects described herein. Here, we will explain the estimated mechanism by which the toner according to this embodiment exhibits the effect of "excellent low-temperature fixation in that it can form an image with excellent bending strength while suppressing the occurrence of low-temperature offset when fixed at low temperatures, and also possesses sufficient heat resistance for storage." In the toner particles 10, the miscible regions (for example, the peripheral area of reference numeral 12 in Figure 1) where a portion of the crystalline polyester resin 12 is miscible with the amorphous polyester resin 11 contain a large amount of long-chain fatty acid components. Fatty acid metal salts are composed of a central metal ion and fatty acid components. The fatty acid component of the first fatty acid metal salt 15 impregnated into the toner particles 10 blends well with the areas in the crystalline polyester resin 12 where long-chain fatty acid components are abundant, i.e., the areas of compatibility. Therefore, the first fatty acid metal salt 15 is well dispersed within the toner particles 10 via the crystalline polyester resin 12, ensuring even distribution. This prevents the deterioration of the toner's heat resistance due to the impregnation of the first fatty acid metal salt 15 within the toner particles 10. The metal ions in the first fatty acid metal salt 15 interact with the colorant 14 (pigment as a colorant), and the crystalline polyester resin 12 interacts with the amorphous polyester resin 11. Therefore, the