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EP-4394516-B1 - TONER FOR DEVELOPING ELECTROSTATIC CHARGE IMAGE, ELECTROSTATIC CHARGE IMAGE DEVELOPER, TONER CARTRIDGE, PROCESS CARTRIDGE, IMAGE FORMING APPARATUS, AND IMAGE FORMING METHOD

EP4394516B1EP 4394516 B1EP4394516 B1EP 4394516B1EP-4394516-B1

Inventors

  • SAKAMOTO, SHINYA
  • SATO, NARUMASA
  • TANAKA, YUMI

Dates

Publication Date
20260506
Application Date
20230605

Claims (16)

  1. A toner for developing an electrostatic charge image, the toner comprising: toner particles containing: a binder resin containing an amorphous resin and a crystalline resin; and resin particles, wherein: in differential scanning calorimetry, an endothermic peak temperature Tc of the crystalline resin is 60°C or higher and 75°C or lower; a ratio (Q1/Q2) of a heat absorption Q1 of the crystalline resin calculated by performing differential scanning calorimetry on the toner that has been melted at 150°C, then cooled to a temperature 10°C lower than the endothermic peak temperature Tc, and then retained thereat for 1 minute, to a heat absorption Q2 of the crystalline resin calculated by performing differential scanning calorimetry on the toner that has been melted at 150°C, then cooled to a temperature 10°C lower than the endothermic peak temperature Tc, and then retained thereat for 30 minutes is 0.15 or more; a maximum value of a loss coefficient tan δ at 50°C or higher and 70°C or lower is less than 1.2; an amount of the crystalline resin contained relative to a total amount of the amorphous resin and the crystalline resin is 15 mass% or more and 25 mass% or less; and the resin particles are crosslinked resin particles, wherein the heat absorption and the loss coefficient tan δ are determined by the methods set out in the description.
  2. The toner for developing an electrostatic charge image according to claim 1, wherein the resin particles has a storage modulus G'(Rp) at 50°C of 1 × 10 5 Pa or more and 5 × 10 7 Pa or less, wherein the storage modulus G'(Rp) is determined by the method set out in the description.
  3. The toner for developing an electrostatic charge image according to claim 1 or 2, wherein the resin particles have a number-average particle diameter of 60 nm or more and 300 nm or less, wherein the number-average particle diameter is determined by the method set out in the description.
  4. The toner for developing an electrostatic charge image according to any one of claims 1 to 3, wherein an amount of the resin particles contained relative to the entire toner particles is 2 mass% or more and 30 mass% or less.
  5. The toner for developing an electrostatic charge image according to any one of claims 1 to 4, wherein the crosslinked resin particles are styrene-(meth)acrylic copolymer resin particles.
  6. The toner for developing an electrostatic charge image according to any one of claims 1 to 5, wherein a difference (SP value (Amo) - SP value (Cry)) between a solubility parameter SP value (Amo) of the amorphous resin and a solubility parameter SP value (Cry) of the crystalline resin is 0 or more and 0.9 or less, wherein the solubility parameter SP value (Amo) and the solubility parameter SP value (Cry) are determined by the methods set out in the description.
  7. The toner for developing an electrostatic charge image according to any one of claims 1 to 6, wherein, in measuring dynamic viscoelasticity of components in the toner particles other than the resin particles, a storage modulus G'(t) at 50°C observed during heating at 2°C/minute is 1 × 10 8 Pa or more, and a temperature at which the storage modulus G'(t) reaches below 1 × 10 5 Pa is 70°C or higher and 90°C or lower, wherein the storage modulus G'(t) is determined by the method set out in the description.
  8. The toner for developing an electrostatic charge image according to any one of claims 1 to 7, wherein the binder resin is a polyester resin.
  9. The toner for developing an electrostatic charge image according to any one of claims 1 to 8, wherein: the amorphous resin contains an amorphous polyester resin that has an aliphatic dicarboxylic acid unit; the crystalline resin contains a crystalline polyester resin that has an aliphatic dicarboxylic acid unit; the amorphous polyester resin contains an amorphous polyester resin that has a unit represented by formula (1); the crystalline polyester resin contains a crystalline polyester resin that has a unit represented by formula (2); in the amorphous polyester resin that has the aliphatic dicarboxylic acid unit, the unit represented by formula (1) accounts for 1 mass% or more and 30 mass% or less of all dicarboxylic acid units; and in the crystalline polyester resin that has the aliphatic dicarboxylic acid unit, the unit represented by formula (2) accounts for 60 mass% or more and 100 mass% or less of all dicarboxylic acid units, where, in formula (1), n represents an integer of 4 or more and 12 or less, and, in formula (2), m represents an integer of 4 or more and 12 or less.
  10. The toner for developing an electrostatic charge image according to claim 9, wherein a mass ratio R1 of the unit represented by formula (1) to all dicarboxylic acid units in the entire amorphous polyester resin and a mass ratio R2 of the unit represented by formula (2) to all dicarboxylic acid units in the entire crystalline polyester resin satisfy 0.01 ≤ R1/R2 ≤ 0.40.
  11. The toner for developing an electrostatic charge image according to any one of claims 1 to 10, wherein a storage modulus G' at 75°C of the toner during heating is 2 × 10 4 Pa or more and 1 × 10 6 Pa or less.
  12. An electrostatic charge image developer comprising the toner for developing an electrostatic charge image according to any one of claims 1 to 11.
  13. A toner cartridge detachably attachable to an image forming apparatus, the toner cartridge comprising the toner for developing an electrostatic charge image according to any one of claims 1 to 11.
  14. A process cartridge detachably attachable to an image forming apparatus, the process cartridge comprising a developing unit that contains the electrostatic charge image developer according to claim 12 and develops an electrostatic charge image on a surface of an image bearing member into a toner image by using the electrostatic charge image developer.
  15. An image forming apparatus comprising: an image bearing member; a charging unit that charges a surface of the image bearing member; an electrostatic charge image forming unit that forms an electrostatic charge image on the charged surface of the image bearing member; a developing unit that contains the electrostatic charge image developer according to claim 12 and develops an electrostatic charge image on a surface of an image bearing member into a toner image by using the electrostatic charge image; a transfer unit that transfers the toner image on the surface of the image bearing member onto a surface of a recording medium; and a fixing unit that fixes the transferred toner image onto the surface of the recording medium.
  16. An image forming method comprising: charging a surface of an image bearing member; forming an electrostatic charge image on the charged surface of the image bearing member; developing the electrostatic charge image on the surface of the image bearing member into a toner image by using the electrostatic charge image developer according to claim 12; transferring the toner image on the surface of the image bearing member onto a surface of a recording medium; and fixing the transferred toner image onto the surface of the recording medium.

Description

Background (i) Technical Field The present disclosure relates to a toner for developing an electrostatic charge image, an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method. (ii) Related Art Japanese Unexamined Patent Application Publication No. 2017-009982 proposes a toner that is thermally fixed to an image carrier and that has a storage modulus G' satisfying conditions below as measured with a rheometer: · Storage modulus G' at 100°C in a heating process is 1 × 103 to 1 × 106 Pa· Storage modulus G' at 100°C in a cooling process is 1 × 103 to 1 × 106 Pa where the value of storage modulus G' at 100°C is higher in the cooling process than in the heating process. Japanese Unexamined Patent Application Publication No. 2014-199423 proposes a toner for developing an electrostatic charge image, the toner containing at least a binder resin and a coloring agent, in which the binder resin contains a crystalline resin (A), the crystalline resin (A) contains two or more crystalline resins (a), and an endothermic peak temperature group that includes all endothermic peak temperatures of the two or more crystalline resins (a) has two or more different endothermic peak temperatures. Japanese Unexamined Patent Application Publication No. 2011-197659 proposes a toner for developing an electrostatic latent image, the toner containing a binder resin and a coloring agent, in which the binder resin contains a crystalline resin and an amorphous resin obtained from a radically polymerizable monomer unit containing a styrene monomer and a (meth)acrylate monomer, and in which a ratio (Q2/Q1) of a heat absorption Q2 based on an endothermic peak derived from the crystalline resin in a second heating process of increasing the temperature from 0°C to 200°C to a heat absorption Q1 based on an endothermic peak derived from the crystalline resin in a first heating process of increasing the temperature from 0°C to 200°C is 0.85 or more. Japanese Unexamined Patent Application Publication No. 2016-070956 proposes a toner for developing an electrostatic charge image, the toner containing a binder resin and a crystalline substance, in which, in a DSC curve measured with a differential scanning calorimeter, an endothermic peak is present at 90°C or higher and 115°C or lower; and, in dynamic viscoelasticity measurement, a local maximum of tan δ is present at 115°C or higher and 125°C or lower, the local maximum of tan δ is 1 or more and 2 or less, and G" at the local maximum of tan δ is 103 or more and 104 or less. International Publication No. 2006/035862 proposes a toner for developing an electrostatic charge image, the toner containing at least a binder resin and a coloring agent, in which the binder resin contains an amorphous resin and a crystalline resin, and, in a DSC curve of the toner obtained in a heating process measured by a differential scanning calorimeter, there is an endothermic peak having a starting point onset temperature of 100 to 150°C, an end point onset temperature of 150 to 200°C, and a half width of 10 to 40°C. Japanese Unexamined Patent Application Publication No. 2021-117422 proposes a toner for developing an electrostatic charge image, the toner containing toner base particles that contain at least a binder resin, a coloring agent, and a releasing agent, in which the binder resin contains at least a crystalline polyester resin, and, in a temperature-modulated viscoelasticity measurement of the toner for developing an electrostatic charge image, the ratio [tan δ(60°C)/tan δ(45°C)] of the loss tangent tan δ(45°C) at a temperature of 45 °C and the loss tangent tan δ(60°C) at a temperature of 60°C is in the range of 2.5 to 4.0, and there is one local maximum in a tan δ curve plotted versus temperature in the temperature range of 60 to 70°C. Japanese Unexamined Patent Application Publication No. 2020-204686 proposes a toner for developing an electrostatic charge image, the toner containing toner base particles that contain at least a releasing agent and a binder resin, in which the binder resin contains at least a crystalline polyester resin, and, in a temperature-modulated viscoelasticity measurement of the toner for developing an electrostatic charge image, the following formulae (1) to (3) are satisfied, and, in the temperature range of 60 to 70°C, a tan δ curve as a function of temperature has one local maximum, where the tangent losses (tan δ) of dynamic viscoelasticity at temperature of 45°C, 50°C, 55°C, and 60°C are respectively represented by tan δ(45°C), tan δ(50°C), tan δ(55°C), and tan δ(60°C), the value of the ratio of tan δ(55°C) to tan δ(45°C) is represented by [tan δ(55°C)/tan δ(45°C)], the value of the ratio of tan δ(60°C) to tan δ(50°C) is represented by [tan δ(60°C)/tan δ(50°C)], and the value of the ratio of tan δ(60°C) to tan δ(55°C) is represented by [tan δ(60°C)/tan δ(55°C)]: tanδ60°C/tanδ55°C<tanδ55°C/tanδ45°C 1.0≤tan