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DE-102025146641-A1 - TONER

DE102025146641A1DE 102025146641 A1DE102025146641 A1DE 102025146641A1DE-102025146641-A1

Abstract

A toner comprising a toner particle containing an amorphous polyester resin and a crystalline polyester resin is provided, wherein the amorphous polyester resin contains a modified amorphous polyester resin having a linear alkyl compound and condensed at one end, and the crystalline polyester resin contains a modified crystalline polyester resin having a linear alkyl compound and condensed at one end, wherein the number mean D<sub> A</sub> (nm) of the longitudinal axis lengths of the crystals of the crystalline polyester resin viewed on the cross-section of a sample A obtained by melting the toner at 150 °C and then cooling the toner to 25 °C, and the number mean D<sub> B </sub> (nm) of the longitudinal axis lengths of the crystals of the crystalline polyester resin viewed on the cross-section of a sample B obtained by leaving sample A at 50 °C for 72 hours, satisfy specific relationships.

Inventors

  • Junichi Tamura
  • Takeshi Hashimoto
  • Megumi Shiino
  • Hayato Ida

Assignees

  • CANON KABUSHIKI KAISHA

Dates

Publication Date
20260513
Application Date
20251112
Priority Date
20241113

Claims (12)

  1. Toner comprising a toner particle comprising an amorphous polyester resin and a crystalline polyester resin, wherein the amorphous polyester resin comprises a modified amorphous polyester resin having at least one linear alkyl compound condensed at one end, selected from the group consisting of linear C16-24 aliphatic monocarboxylic acids and linear C16-24 aliphatic monoalcohols; the crystalline polyester resin comprises a modified crystalline polyester resin having at least one linear alkyl compound condensed at one end, selected from the group consisting of linear C16-24 aliphatic monocarboxylic acids and linear C16-24 aliphatic monoalcohols; and if a cross-section of a sample A, obtained by melting the toner at 150 °C and subsequently cooling the toner to 25 °C at a rate of 100 °C/min, is examined using a transmission electron microscope, and a number-average of the longitudinal axis lengths of the crystals of the crystalline polyester resin viewed on the cross-section is taken as D A (nm), and if a cross-section of a sample B, obtained by leaving sample A at 50 °C for 72 hours, is examined using a transmission electron microscope, and a number-average of the longitudinal axis lengths of the crystals of the crystalline polyester resin viewed in the cross-section is taken as D B (nm), D A and D B satisfy the following expressions (1) and (2): 10 nm ≤ D A ≤ 100 nm 1 nm ≤ D B − D A ≤ 20 nm
  2. Toner after Claim 1 , where D A and D B satisfy the following expressions (3) and (4): 10 nm ≤ D A ≤ 50 nm 20 nm ≤ D B ≤ 70 nm
  3. Toner after Claim 1 or 2 , wherein, when the cross-section of sample B is considered, the crystals of the crystalline polyester resin considered in the cross-section have an average aspect ratio of 2.5 to 5.0.
  4. Toner after Claim 1 or 2 , wherein, if an SP value of the modified amorphous polyester resin is taken as SP A (cal/cm 3 ) 0.5 , and an SP value of the modified crystalline polyester resin is taken as SP C (cal/cm 3 ) 0.5 , the SP A and the SP C satisfy the following expression (5): 0,8 ≤ SP A − SP C ≤ 1,2
  5. Toner after Claim 1 or 2 , wherein the crystalline polyester resin has a W C content ratio of 5.0 to 20.0 wt%, based on the mass of the toner particle.
  6. Toner after Claim 1 or 2 , wherein, where a content ratio of the crystalline polyester resin, based on the mass of the toner particle, is taken as W C (mass %), and an average area ratio of the crystals of the crystalline polyester resin in an area of a viewing region, when viewing the cross-section of sample A using a transmission electron microscope, is taken as S A (area %), the W C and the S A satisfy the following expression (6): 0,1 ≤ S A / W C ≤ 0,6
  7. Toner after Claim 1 or 2 , wherein, where a content ratio of the crystalline polyester resin, based on the mass of the toner particle, is taken as W C (mass-%), and an average area ratio of the crystals of the crystalline polyester resin in an area of a viewing region, when viewing the cross-section of sample B using a transmission electron microscope, is taken as S B (area-%), the W C and the S B satisfy the following expression (7): 0,3 ≤ S B / W C ≤ 0,8
  8. Toner after Claim 1 or 2 , wherein the modified crystalline polyester resin has a weight-averaged molecular weight of 15000 to 25000.
  9. Toner after Claim 1 or 2 , wherein the linear alkyl compound condensed onto one end of the modified amorphous polyester resin has a larger number of carbon atoms than the linear alkyl compound condensed onto one end of the modified crystalline polyester resin.
  10. Toner after Claim 1 or 2 , wherein the linear alkyl compound condensed onto one end of the modified amorphous polyester resin is stearic acid, and the linear alkyl compound condensed onto one end of the modified crystalline polyester resin is behenic acid.
  11. Toner after Claim 1 or 2 , wherein the modified crystalline polyester resin comprises a monomer unit corresponding to ethylene glycol and a monomer unit corresponding to dodecanedioic acid.
  12. Toner after Claim 1 or 2 , wherein a proportion of ends where the linear alkyl compound is condensed under molecular chain ends of the modified amorphous polyester resin is at least 0.5 mol% and less than 25 mol%, and a proportion of ends where the linear alkyl compound is condensed under molecular chain ends of the modified crystalline polyester resin is 15 to 75 mol%.

Description

BACKGROUND Technical area The present disclosure relates to a toner used in electrophotographic systems, electrostatic recording systems and electrostatic printing systems. Description of the related prior art In recent years, there has been a growing demand for electrophotographic devices, such as full-color printers and copiers, to offer added value, including high productivity, high image quality, and high stability. To achieve high productivity, it is essential to melt the toner more quickly during the fusing step. Specifically, a toner is needed that can be fixed at a lower temperature and exhibits excellent low-temperature fusing properties. The disclosed Japanese patent application no. 2004-046095 This toner, which exhibits excellent low-temperature fixability, contains a crystalline polyester as a binder resin. The crystalline polyester has a higher melting point than an amorphous polyester and acts as a plasticizer. Therefore, the crystalline polyester is a material that is effective for fixing the toner at low temperatures. However, if the compatibility between the crystalline polyester and the amorphous polyester is increased to improve low-temperature fixability, a case may arise where the crystalline polyester does not crystallize in a toner, and the charge conservation property is deteriorated. Therefore, the disclosed Japanese patent application No. 2016-110150 a manufacturing process of accelerated crystallization of a crystalline polyester by annealing a toner in order to achieve both low-temperature fixability and charge conservation properties. In a toner containing a crystalline resin with low-temperature fixability, the binder resin and plasticizer in the toner melt, which forms a fixed image, often remain compatible. As a result, the toner's heat resistance decreases, and the toner melt tends to adhere to the back of the paper, which may have an output image or another fixed image on it, potentially causing an image defect. One such defect is sheet adhesion. Particularly in the case of double-sided printing, fixed image elements are inevitably placed in contact with each other, which can lead to image defects more readily than in single-sided printing. Therefore, a toner capable of achieving both low-temperature fixation and resistance to paper adhesion was required. Meanwhile, if a fixed image printed using a toner containing a crystalline resin is stored for a long period, the crystalline resin can gradually anneal, crystallization can progress, and a needle-like crystal domain with a large aspect ratio can form in the fixed image. Once crystallized, the resin becomes brittle, and if the fixed image is bent, cracks can easily appear, potentially leading to image defects. According to investigations by the present inventors, the toner meets the disclosed requirements. Japanese patent application no. 2016-110150 Both low-temperature fixability and charge conservation properties are preserved by annealing in a toner state, but crystallization is delayed after fixing. As a result, resistance to sheet adhesion decreases, and crystallization progresses during long-term storage, resulting in a decrease in wrinkle resistance. SUMMARY The present disclosure provides a toner that exhibits excellent low-temperature fixability and charge retention properties, suppresses sheet adhesion immediately after fixing, and does not easily lose its resistance to wrinkling, even during long-term storage. The present disclosure relates to a toner comprising a toner particle comprising an amorphous polyester resin and a crystalline polyester resin, wherein the amorphous polyester resin comprises a modified amorphous polyester resin having at least one linear alkyl compound condensed at one end, selected from the group consisting of linear C16-24 aliphatic monocarboxylic acids and linear C16-24 aliphatic monoalcohols; the crystalline polyester resin comprises a modified crystalline polyester resin having at least one linear alkyl compound condensed at one end, selected from the group consisting of linear C16-24 aliphatic monocarboxylic acids and linear C16-24 aliphatic monoalcohols; and when a cross-section of a sample A, obtained by melting the toner at 150 °C and subsequently cooling the toner to 25 °C at a rate of 100 °C/min, is viewed using a transmission electron microscope, and a number mean of the longitudinal axis lengths of the crystals of the crystalline polyester resin viewed on the cross-section is taken as D A (nm), and when a cross-section of a sample B, obtained by leaving sample A at 50 °C for 72 hours, is viewed using a transmission electron microscope, and a number mean of the longitudinal axis lengths of the crystals of the crystalline polyester resin viewed in the cross-section is taken as D B (nm), that D A and D B satisfy the following expressions (1) and (2): 10 nm≤DA≤100 nm1 nm≤DB−DA≤20 nm The present disclosure provides a toner that exhibits excellent low-temperature fixability and ch