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CN-117222947-B - Electrophotographic member, process cartridge, electrophotographic image forming apparatus, and electrophotographic manufacturing method thereof

CN117222947BCN 117222947 BCN117222947 BCN 117222947BCN-117222947-B

Abstract

An electrophotographic member comprising a mandrel and an elastic layer on the outer periphery of the mandrel, the elastic layer comprising a polyurethane elastomer comprising a matrix and domains dispersed in the matrix, parameters a and B satisfying a < B relationship, wherein parameter a represents a viscoelastic term of each of the plurality of domains and parameter B represents a viscoelastic term of the matrix. The micro rubber hardness of the elastic layer at a temperature of 23 ℃ is 20 or more and 50 or less, and in an indentation test of the elastic layer with a nanoindenter at 23 ℃, wherein the test comprises pressing into the elastic layer with a vickers indenter at a loading rate of 10mN/30sec, holding under a load of 10mN for 60 seconds, and then unloading, the strain after unloading for 5 seconds is 1 μm or less.

Inventors

  • Cross limit political affairs great
  • SATO KANA
  • HINO TETSUO
  • XIAO CHUANLIANG
  • HIRATANI TAKAYUKI

Assignees

  • 佳能株式会社

Dates

Publication Date
20260508
Application Date
20220408
Priority Date
20210426

Claims (10)

  1. 1. An electrophotographic member, characterized in that it comprises: Mandrel, and An elastic layer provided on the outer periphery of the mandrel, The elastic layer comprises a polyurethane elastomer comprising a matrix and a plurality of domains dispersed in the matrix, The parameter a and the parameter B satisfy the relation a < B, wherein, The parameter A representing a viscoelastic term of each of the plurality of domains and the parameter B representing a viscoelastic term of the matrix, the parameters A and B being measured in a viscoelastic image of a cross section in a thickness direction of the elastic layer using a scanning probe microscope, After having acquired a viscoelastic image, determining parameters each representing a viscoelastic term in each observation area at 10 points of each of the matrix and the domain, and taking their respective average values as a parameter a representing the viscoelastic term of the domain and a parameter B representing the viscoelastic term of the matrix, wherein the values of the parameter a and the parameter B are each expressed in mV, the larger the values thereof represent the higher the elasticity, The elastic layer has a microrubber hardness of 20 or more and 50 or less at a temperature of 23℃, and In an indentation test of the elastic layer with a nanoindenter at 23 ℃, wherein a vickers indenter is pressed into the elastic layer at a loading speed of 10mN/30sec and maintained under a load of 10mN for 60 seconds, and then unloaded, a strain after unloading for 5 seconds is 1 μm or less.
  2. 2. The electrophotographic member according to claim 1, wherein the elastic modulus of the substrate is 2MPa or more and 8MPa or less.
  3. 3. The electrophotographic member according to claim 1, wherein, When the length of the elastic layer in the length direction is defined as L, In each cross section in the thickness direction of the elastic layer at three positions of the center in the length direction of the elastic layer and L/4 from both ends of the elastic layer toward the center, square observation regions each having a side length of 50 μm are arbitrarily provided in a thickness region of 100 μm from the outer surface of the elastic layer, All three of the observation regions each satisfy the following requirements (1) and (2): The ratio of the sum of the cross-sectional areas of the plurality of domains is 15% to 45% of the area of the observation region; the ratio of the number of the plurality of domains having the respective cross-sectional areas of 0.1% to 13.0% with respect to the respective observation regions is 70% or more.
  4. 4. An electrophotographic member according to claim 1, wherein a ratio of the number of the plurality of domains of which respective circularities of all three of the observation regions are 0.60 or more and 0.95 or less is 70% or more.
  5. 5. The electrophotographic member according to claim 1, Wherein the matrix comprises a polyurethane elastomer comprising a polycarbonate structural unit represented by the general formula (1) as a repeating structural unit, and Wherein each of the plurality of domains includes a polyether structural unit represented by the general formula (2) as a repeating structural unit: General formula (1) Wherein R 1 represents an alkylene group having 3 to 9 carbon atoms; General formula (2) Wherein R 2 represents an alkylene group having 3 to 5 carbon atoms.
  6. 6. The electrophotographic member according to claim 5, wherein R 1 in the repeating structural unit represented by the general formula (1) represents an alkylene group having a branched structure having 3 to 9 carbon atoms.
  7. 7. The electrophotographic member according to claim 5, wherein R 2 in the repeating structural unit represented by the general formula (2) represents an alkylene group having a branched structure having 3 to 5 carbon atoms.
  8. 8. A process cartridge configured to be detachably mountable to an image forming apparatus, wherein said process cartridge comprises the electrophotographic member according to any one of claims 1 to 7.
  9. 9. An electrophotographic image forming apparatus, characterized in that it comprises the electrophotographic member according to any one of claims 1 to 7.
  10. 10. A method of manufacturing an electrophotographic member, characterized in that the electrophotographic member is an electrophotographic member according to any one of claims 1 to 7, comprising the steps of: (i) Reacting a first polyether having at least two isocyanate groups and a first polycarbonate polyol having at least two hydroxyl groups with each other to obtain a urethane-reactive emulsifier having at least two hydroxyl groups; (ii) Obtaining a dispersion in which droplets each comprising at least a portion of the urethane-reactive emulsifier are dispersed in a second polycarbonate polyol; (iii) Mixing the dispersion and a polyisocyanate having at least two isocyanate groups with each other to obtain a mixture for forming an elastic layer, and (Iv) The urethane-reactive emulsifier, the second polycarbonate polyol and the polyisocyanate in the mixture for forming an elastic layer are reacted with each other on the surface of the mandrel, thereby obtaining the elastic layer.

Description

Electrophotographic member, process cartridge, electrophotographic image forming apparatus, and electrophotographic manufacturing method thereof Technical Field The present disclosure relates to an electrophotographic member for an electrophotographic image forming apparatus (hereinafter sometimes simply referred to as "image forming apparatus"), such as a copier or printer using an electrophotographic system, and a method of manufacturing the electrophotographic member. The present disclosure also relates to a process cartridge and an electrophotographic image forming apparatus. Background An image forming apparatus employing an electrophotographic system (a copying machine, a facsimile, a printer, or the like using the electrophotographic system) mainly includes an electrophotographic photosensitive member (hereinafter sometimes referred to as a "photosensitive member"), a charging device, an exposing device, a developing device, a transferring device, and a fixing device. In the image forming apparatus, the photosensitive member is first charged by a charging member (hereinafter sometimes referred to as a "charging roller") and then exposed to light. Thus, an electrostatic latent image is formed on the photosensitive member. In addition, the toner in the toner container is applied to a toner bearing member (hereinafter sometimes referred to as a "developing roller") by a toner regulating member, and is conveyed to a developing region by the developing roller. Then, the electrostatic latent image on the photosensitive member is developed at the abutting portion between the photosensitive member and the developing roller with the toner conveyed to the developing region. Thereafter, the toner on the photosensitive member is transferred onto the recording sheet by a transfer means (means), and fixed with heat and pressure. The toner remaining on the photosensitive member is removed by the cleaning member. As materials for the elastic layer of each of such a charging roller and developing roller, silicone rubber, acrylonitrile-butadiene rubber, epichlorohydrin rubber, and urethane elastomer (urethane elastomer) have hitherto been used. Among these materials, urethane elastomers have satisfactory abrasion resistance and are therefore suitable as materials for the elastic layer. However, urethane elastomers are generally prone to compression set. Therefore, when a specific portion of the developing roller including the elastic layer including the urethane elastomer abuts the toner regulating member for a long time and the specific portion is deformed, the deformation is not easily recovered (recovered). When image formation is performed on a developing roller in which a specific portion is deformed, an electrophotographic image to be obtained may have a streak-like defect at a position corresponding to the deformed portion. Similarly, in a charging roller including an elastic layer including a urethane elastomer, a charging failure due to deformation occurring in a specific portion of the charging roller may also occur, and an electrophotographic image to be obtained may have a defect. When the hardness of the urethane elastomer is low, compression set tends to increase, and the above-described defect is more likely to occur. In patent document 1, there is disclosed a conductive roller comprising a conductive elastic layer formed of a urethane elastomer obtained by reacting a polyisocyanate formed of a trimer of hexamethylene diisocyanate, a biuret thereof or a mixture thereof and a polyol containing a high molecular weight polypropylene glycol as a main component with each other at an isocyanate index of 80 to 120. Patent document 1 discloses that the conductive elastic layer reduces permanent deformation of the roller, and thus a conductive roller excellent in recovery from deformation caused by pressure contact with the photosensitive member and pressure contact with the roller or the blade is obtained. [ Quotation list ] [ Patent literature ] Patent document 1 Japanese patent application laid-open No. H09-34216 [ Non-patent literature ] Non-patent document 1, IEEE system, metropolitan area network and network journal (IEEE Transactions on SYSTEMS, MAN, AND CYBERNETICS), volume SMC-9, 1 st edition, 1979, month 1, pages 62 to 66. Disclosure of Invention Problems to be solved by the invention The present inventors studied the conductive roller according to patent document 1. As a result, the present inventors found that the urethane elastomer according to patent document 1 has room for improvement as a constituent material of an elastic layer for each of a developing roller and a charging roller of a high-speed image forming apparatus. One aspect of the present disclosure is directed to providing an electrophotographic member having low hardness and fast recovery from deformation. Another aspect of the present disclosure is directed to a method of manufacturing an electrophotographic member having low hardness