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CN-116082800-B - Electrophotographic belt and electrophotographic image forming apparatus

CN116082800BCN 116082800 BCN116082800 BCN 116082800BCN-116082800-B

Abstract

The present invention relates to an electrophotographic belt and an electrophotographic image forming apparatus. The electrophotographic belt includes a biaxially stretched cylindrical film as a base layer, wherein the biaxially stretched cylindrical film contains a crystalline polyester, an amorphous polyester, and carbon black, the content of the carbon black is 2.0 mass% or more with respect to the biaxially stretched cylindrical film, and the surface resistivity measured on the surface of the biaxially stretched cylindrical film under an environment of 23 ℃ and 50% rh is 1×10 3 Ω/≡and 1×10 13 Ω/≡and 3.00 or less, wherein a (Ω/≡) represents the surface resistivity of the biaxially stretched cylindrical film after the biaxially stretched cylindrical film is left to stand under an environment of 23 ℃ and 50% rh for 24 hours, and B (Ω/≡) represents the surface resistivity of the biaxially stretched cylindrical film after the biaxially stretched cylindrical film is left to stand under an environment of 30 ℃ and 80% rh for 24 hours.

Inventors

  • Kotoh hiroomi

Assignees

  • 佳能株式会社

Dates

Publication Date
20260512
Application Date
20221104
Priority Date
20211105

Claims (12)

  1. 1. An electrophotographic belt comprising a biaxially stretched cylindrical film as a base layer, characterized in that, The biaxially stretched cylindrical film comprises a crystalline polyester, a non-crystalline polyester and carbon black, The content of the carbon black is 2.0 mass% or more and 15.0 mass% or less with respect to the biaxially stretched cylindrical film, and A surface resistivity measured on a surface of the biaxially stretched cylindrical film in an environment having a temperature of 23 ℃ and a relative humidity of 50% of 1×10 3 Ω/≡or more and 1×10 13 Ω/≡or less, and A/B is 3.00 or less, wherein a represents a surface resistivity measured on a surface of the biaxially stretched cylindrical film after the biaxially stretched cylindrical film is left to stand for 24 hours in an environment of 23 ℃ and a relative humidity of 50%, the unit of a is Ω/≡and B represents a surface resistivity measured on a surface of the biaxially stretched cylindrical film after the biaxially stretched cylindrical film is left to stand for 24 hours in an environment of 30 ℃ and a relative humidity of 80%, the unit of B is Ω/≡.
  2. 2. The electrophotographic belt according to claim 1, wherein a/B is 0.33 or more and 3.00 or less.
  3. 3. The electrophotographic belt according to claim 1, wherein a/B is 1.00 or more and 3.00 or less.
  4. 4. The electrophotographic belt according to claim 1, wherein the biaxially stretched cylindrical film contains an ion conductive agent, and the total amount of the ion conductive agent is 2.0 mass% or less with respect to the biaxially stretched cylindrical film.
  5. 5. The electrophotographic belt according to claim 1, wherein the biaxially stretched cylindrical film contains no ion conductive agent.
  6. 6. The electrophotographic belt according to claim 1, wherein the crystalline polyester comprises at least one selected from the group consisting of polyalkylene terephthalates, polyalkylene naphthalates, polyalkylene isophthalates, and copolymers comprising these components.
  7. 7. The electrophotographic belt according to claim 1, wherein the amorphous polyester comprises monomer units derived from at least one phthalic acid selected from the group consisting of terephthalic acid, phthalic acid, and isophthalic acid, and from at least two diols selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, and cyclohexanedimethanol.
  8. 8. The electrophotographic belt according to claim 1, wherein the content of the amorphous polyester is 100 mass% or less with respect to the content of the crystalline polyester.
  9. 9. The electrophotographic belt according to claim 1, wherein the DBP absorption amount of the carbon black is 300mL/100g or more.
  10. 10. The electrophotographic belt according to claim 1, wherein the biaxially stretched cylindrical film has a tensile elastic modulus Ep in a circumferential direction and a tensile elastic modulus Ea in a direction perpendicular to the circumferential direction of 1000MPa or more.
  11. 11. The electrophotographic belt according to claim 1, wherein the shrinkage αp of the electrophotographic belt in the circumferential direction and the shrinkage αa of the electrophotographic belt in a direction perpendicular to the circumferential direction are each 2.0% or more.
  12. 12. An electrophotographic image forming apparatus, characterized in that it comprises the belt for electrophotography according to any one of claims 1 to 11 as an intermediate transfer belt.

Description

Electrophotographic belt and electrophotographic image forming apparatus Technical Field The present disclosure relates to an electrophotographic belt and an electrophotographic image forming apparatus including the same. Background In an electrophotographic image forming apparatus, an electrophotographic belt formed of a thermoplastic resin and having an endless shape is used as a conveying transfer belt for conveying a transfer material, or an intermediate transfer belt. Such electrophotographic belt is required to have high strength and conductivity in the range of, for example, 1×10 3 Ω/≡ (Ω/square) to 1×10 13 Ω/≡. Japanese patent application laid-open No. 2006-233650 discloses the problem of a preform (preform) containing a large amount of carbon black, that is, reduced elongation at the time of stretching the preform and difficulty in biaxially stretching the preform. Then, it is disclosed that such problems can be solved by using a thermoplastic resin and a thermoplastic elastomer having specific constituent units. Japanese patent application laid-open No. 2006-233650 also discloses in its examples 1 to 3 that even if a large amount of carbon black is contained (more than 10 parts by mass relative to 100 parts by mass of the resin component), a preform can be biaxially stretched by using polyethylene naphthalate, polyethylene terephthalate, and resins of two thermoplastic elastomers (trade names: pelestat 6321;Sanyo Chemical Industries,Ltd, and trade names: tuftec M1913; ASAHI KASEI corp.), and a biaxially stretched cylindrical film that can be used for an intermediate transfer belt is obtained. As used herein, the thermoplastic elastomer "Pelestat 6321" is a polyetheresteramide and functions as an ionic conductor. Thus, in some cases, the electrical conductivity of the biaxially stretched cylindrical film obtained here varies depending on the surrounding environment. The present inventors have recognized that, in order to form high-quality electrophotographic images more stably even under various environments, a change in the surface resistance of an electrophotographic belt due to the surrounding environment is a problem to be solved. Disclosure of Invention At least one aspect of the present disclosure is directed to providing an electrophotographic belt that facilitates stable formation of high-quality electrophotographic images under various environments. Another aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus that can form high-quality electrophotographic images. According to one aspect of the present disclosure, there is provided an electrophotographic belt having a biaxially stretched cylindrical film as a base layer. The biaxially stretched cylindrical film contains a crystalline polyester, an amorphous polyester and carbon black. The content of carbon black is 2.0 mass% or more relative to the biaxially stretched cylindrical film, and the surface resistivity measured on the surface of the biaxially stretched cylindrical film in an environment of 23 ℃ and 50% relative humidity is 1×10 3 Ω/≡and 1×10 13 Ω/≡or less. Further, a/B is 3.00 or less, where a (Ω/≡) represents the surface resistivity measured on the surface of the biaxially stretched cylindrical film after the biaxially stretched cylindrical film was left to stand for 24 hours in an environment where the temperature is 23 ℃ and the relative humidity is 50%, and B (Ω/≡) represents the surface resistivity measured on the surface of the biaxially stretched cylindrical film after the biaxially stretched cylindrical film was left to stand for 24 hours in an environment where the temperature is 30 ℃ and the relative humidity is 80%. According to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including the electrophotographic belt as an intermediate transfer belt. Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. Drawings Fig. 1 shows a schematic sectional view illustrating an example of a full-color electrophotographic image forming apparatus using an electrophotographic method. Fig. 2 is a schematic cross-sectional view of an injection molding apparatus used in the examples. Fig. 3A, 3B, 3C and 3D show schematic cross-sectional views of a primary blow molding apparatus used in the embodiments. Fig. 4 shows a schematic cross-sectional view of a secondary blow molding apparatus used in the examples. Fig. 5A, 5B-1, 5B-2, and 5B-3 show explanatory views of configuration examples of an electrophotographic belt according to the present disclosure. Detailed Description Preferred embodiments of the present disclosure (according to the drawings) will now be described in detail. In the present disclosure, unless otherwise indicated, the expressions "above XX and below YY" and "XX-YY" representing a numerical range are meant t