Patent Application
20240103393
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2022-154083 filed Sep. 27, 2022.
The present invention relates to a conductive member, a charging device, a process cartridge, and an image forming apparatus.
JP2011-022410A discloses “a conductive member including: a substrate; an elastic layer disposed on the substrate; and a surface layer disposed on the elastic layer, the surface layer having a sea/island structure that consists of a sea portion containing a first resin and an island portion containing a second resin, and the surface layer containing carbon black at least in the island portion.”
JP2017-015952A discloses “a conductive member including: a substrate; an elastic layer provided on the substrate; and a surface layer provided on the elastic layer, in which the surface layer has a sea/island structure that consists of a sea portion containing at least a first resin and a conductive agent and an island portion containing at least a second resin, an average diameter of the island portion is 100 nm or more and not more than 1/10 a thickness of the surface layer, and the conductive agent in the sea portion is unevenly distributed in the vicinity of an interface between the sea portion and the island portion.”
Aspects of non-limiting embodiments of the present disclosure relate to a conductive member including: a substrate; an elastic layer provided on the substrate; and a surface layer provided on the elastic layer, in which the surface layer contains a conductive agent and has a sea/island structure that consists of a sea portion containing a first resin and an island portion containing a second resin, an object of the present invention is to provide a conductive member where the occurrence of axial color streaks during formation of an image is suppressed and the occurrence of fogging (occurrence of an image defect in a case where toner particles are attached to a region that is not exposed in a photoreceptor) is also suppressed as compared to a case where a distance R between the island portions and a radius r of the island portion in a cross-section of the surface layer do not satisfy the following Expression (1-1).
−0.20≤R−2r≤0.40 Expression (1-1):
Aspects of certain non-limiting embodiments of the present disclosure address the above advantages and/or other advantages not described above. However, aspects of the non-limiting embodiments are not required to address the advantages described above, and aspects of the non-limiting embodiments of the present disclosure may not address advantages described above.
Configurations for Achieving the Objects Include the Following Aspect.
According to an aspect of the present invention, there is provided a conductive member including: a substrate; an elastic layer provided on the substrate; and a surface layer provided on the elastic layer, in which the surface layer contains a conductive agent and has a sea/island structure that consists of a sea portion containing a first resin and an island portion containing a second resin, and a distance R between the island portions and a radius r of the island portion in a cross-section of the surface layer satisfy the following Expression (1-1),
−0.20≤R−2r≤0.40. Expression (1-1):
Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein:
Hereinafter, an exemplary embodiment that is one example of the present invention will be described. The following description and Examples merely illustrate the present exemplary embodiment and do not limit the scope of the present invention.
An upper limit value or a lower limit value described in one numerical range described in a stepwise manner in the present specification may be replaced with an upper limit value or a lower limit value in another numerical range described in a stepwise manner. In addition, an upper limit value and a lower limit value in a numerical range described in the present specification may be replaced with a value described in examples.
Each of components may include plural kinds of corresponding materials.
In a case where the amount of each of components in a composition is described and plural kinds of materials corresponding to the component are present, unless specified otherwise, the amount of the component refers to the total amount of the plural kinds of materials present in the composition.
Conductive Member
A conductive member according to an exemplary embodiment includes: a substrate; an elastic layer provided on the substrate; and a surface layer provided on the elastic layer, in which the surface layer contains a conductive agent and has a sea/island structure that consists of a sea portion containing a first resin and an island portion containing a second resin, and a distance R between the island portions and a radius r of the island portion in a cross-section of the surface layer satisfy the following Expression (1-1).
−0.20≤R−2r≤0.40 Expression (1-1):
Due to the above-described configuration, a photoreceptor according to the present exemplary embodiment suppresses the occurrence of axial color streaks during formation of an image and suppresses the occurrence of fogging. The reason for this is presumed to be as follows.
In a conductive member including: a substrate; an elastic layer provided on the substrate; and a surface layer provided on the elastic layer, in which the surface layer contains a conductive agent and has a sea/island structure that consists of a sea portion containing a first resin and an island portion containing a second resin, axial color streaks during formation of an image and fogging occur.
In order to suppress the occurrence of axial color streaks during formation of an image and the occurrence of fogging, for example, it is preferable that the resistance of the surface layer is reduced to facilitate the flow of a current.
In the conductive member according to the present exemplary embodiment, the distance R between the island portions and the radius r of the island portion in the cross-section of the surface layer satisfy the following Expression (1-1). By satisfying Expression (1-1), the distance between the island portions is likely to decrease, and the area of a conductive path in the surface layer is likely to increase. Therefore, the resistance of the surface layer decreases.
As a result, in the conductive member according to the present exemplary embodiment, it is presumed that the occurrence of axial color streaks during formation of an image and the occurrence of fogging are suppressed.
As shown in
Hereinafter, the example of the conductive member according to the present exemplary embodiment of the present invention will be described in detail, and a reference numeral given to each of the components will not be described in some cases.
Substrate
The substrate is a cylindrical or columnar conductive member, and the conductivity described herein refers to a volume resistivity of lower than 1013 Ωcm.
Examples of a material of the substrate include metal such as iron (for example, free-cutting steel), copper, brass, stainless steel, aluminum, or nickel. Examples of the substrate include a member (for example, a resin or ceramic member) where an outer peripheral surface is plated and a member (for example, a resin or ceramic member) where a conductive agent is dispersed.
Elastic Layer
The elastic layer contains, for example, an elastic material, a conductive agent, and other additives.
Examples of the elastic material include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluororubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, ethyl ene-propyl ene-di ene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and blended rubbers thereof. In particular, for example, polyurethane, silicone rubber, EPDM, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, NBR, and blended rubbers thereof are preferable. These elastic materials may be foamed or unfoamed.
Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent. Examples of the electronic conductive agent include carbon black such as Ketjen black or acetylene black; pyrolytic carbon or graphite; various conductive metals or alloys such as aluminum, copper, nickel, or stainless steel; conductive metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, or tin oxide-indium oxide solid solution; and an insulating material having a surface that is treated to be conductive. Examples of the ionic conductive agent include perchlorates or chlorates of oniums such as tetraethylammonium or lauryltrimethylammonium; and perchlorates or chlorates of alkali metals or alkali earth metals such as lithium or magnesium. The conductive agents may be used alone or in combination of two or more kinds.
Specific examples of the carbon black include “SPECIAL BLACK 350”, “SPECIAL BLACK 100”, “SPECIAL BLACK 250”, “SPECIAL BLACK 5”, “SPECIAL BLACK 4”, “SPECIAL BLACK 4A”, “SPECIAL BLACK 550”, “SPECIAL BLACK 6”, “COLOR BLACK FW200”, “COLOR BLACK FW2”, and “COLOR BLACK FW2V” manufactured by Orion Engineered Carbons S.A. and “MONARCH 880”, “MONARCH 1000”, “MONARCH 1300”, “MONARCH 1400”, “MOGUL-L”, and “REGAL 400R” manufactured by Cabot Corporation.
The blending amount of the conductive agent is not particularly limited and, in the case of the electronic conductive agent, is desirably in a range of 1 part by mass or more and 30 parts by mass or less and more preferably in a range of 15 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the elastic material. The blending amount of the ionic conductive agent is, for example, desirably in a range of 0.1 parts by mass or more and 5.0 parts by mass or less and more preferably in a range of 0.5 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the elastic material.
Examples of other additives that are blended in the elastic layer include typical materials that are blended in the elastic layer, for example, a softener, a plasticizer, a curing agent, a vulcanizing agent, a vulcanization accelerator, an antioxidant, a surfactant, a coupling agent, and a filler (for example, silica or calcium carbonate).
The average thickness of the elastic layer is, for example, desirably about 1 mm or more and 15 mm or less and more preferably about 2 mm or more and 10 mm or less.
The volume resistivity of the elastic layer is, for example, preferably 103 Ωcm or higher and 1014 Ωcm or lower.
Surface Layer
Composition of Surface Layer
The surface layer contains a conductive agent and has a sea/island structure that consists of a sea portion containing a first resin and an island portion containing a second resin.
Here, “sea/island structure” refers to a structure where at least two resins are mixed in an incompatible state and the island portion as a dispersed phase is provided in the sea portion as a continuous phase.
The sea/island structure is formed by adjusting a difference in solubility parameter (SP value) between the first resin and the second resin and a mixing ratio between the first resin and the second resin. From the viewpoint of easily forming the sea/island structure, the difference in SP value between the first resin and the second resin is, for example, preferably 2 or more and 10 or less.
The mixing ratio between the first resin and the second resin will be described below.
In the present exemplary embodiment, a method of calculating the solubility parameter (SP value) is a method described in “Polymer Handbook 4th Edition, John Wiley & Sons” VII 680 to 683. The solubility parameters of major resins are described in VII 702 to 711 of the document.
Examples of the first resin include an acrylic resin, a cellulose resin, a polyamide resin, copolymer nylon, a polyurethane resin, a polycarbonate resin, a polyester resin, a polyethylene resin, a polyvinyl resin, a polyarylate resin, a styrene-butadiene resin, a melamine resin, an epoxy resin, a urethane resin, a silicone resin, a fluororesin (for example, a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, a polytetrafluoroethylene-hexafluoropropylene copolymer, or polyvinylidene fluoride), and a urea resin. The copolymer nylon is a copolymer containing any one kind or plural kinds among nylon 610, nylon 11, and nylon 12 as polymerization units, and may further contain nylon 6 or nylon 66 as other polymerization units. As the first resin, the elastic material that is blended in the elastic layer may be applied. As the first resin, one kind of resin may be used alone, or two or more kinds of resins may be used in combination.
As the first resin, from the viewpoints of: electrical characteristics or contamination resistance of the surface layer; appropriate hardness or maintainability of the surface layer in a case where the surface layer is provided on the elastic layer; and dispersion suitability or coating film formability of the conductive agent in a case where the surface layer is formed using a dispersion liquid, for example, a polyamide resin (for example, nylon) is preferable, and an N-methoxymethylated polyamide resin (for example, methoxymethylated nylon) is more preferable.
Examples of the second resin include a polyvinyl butyral resin, a polystyrene resin, and polyvinyl alcohol. As the second resin, one kind of resin may be used alone, or two or more kinds of resins may be used in combination.
As the second resin, from the viewpoints of: electrical characteristics or contamination resistance of the surface layer; appropriate hardness or maintainability of the surface layer in a case where the surface layer is provided on the elastic layer; and dispersion suitability or coating film formability of the conductive agent in a case where the surface layer is formed using a dispersion liquid, for example, a polyvinyl butyral resin is preferable.
The content of the second resin is, for example, preferably 10 parts by mass or more and 30 parts by mass or less, more preferably 12 parts by mass or more and 28 parts by mass or less, and still more preferably 15 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of a total mass of the first resin and the second resin.
By adjusting the content of the second resin to be 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the total mass of the first resin and the second resin, the conductive member where the occurrence of axial color streaks during formation of an image is further suppressed can be obtained. The reason for this is presumed to be as follows.
By adjusting the content of the second resin to be 10 parts by mass or more with respect to 100 parts by mass of the total mass of the first resin and the second resin, the occupancy of the island portion in the surface layer increases. Therefore, the area of a conductive path in the surface layer further increases. In addition, by adjusting the content of the second resin to be 30 parts by mass or more with respect to 100 parts by mass of the total mass of the first resin and the second resin, the occupancy of the island portion in the surface layer is excessively high, and the island portion is likely to be dispersed and present in the surface layer in a substantially uniform state.
The total content of the first resin and the second resin is, for example, preferably 50 mass % or more and 95 mass % or less, more preferably 60 mass % or more and 90 mass % or less, and still more preferably 70 mass % or more and 85 mass % or less with respect to the total mass of the surface layer.
Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent. Examples of the electronic conductive agent include carbon black such as Ketjen black or acetylene black; pyrolytic carbon or graphite; various conductive metals or alloys such as aluminum, copper, nickel, or stainless steel; conductive metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, or tin oxide-indium oxide solid solution; and an insulating material having a surface that is treated to be conductive. Examples of the ionic conductive agent include perchlorates or chlorates of oniums such as tetraethylammonium or lauryltrimethylammonium; and perchlorates or chlorates of alkali metals or alkali earth metals such as lithium or magnesium. The conductive agents may be used alone or in combination of two or more kinds.
As the conductive agent, for example, carbon black is suitable.
Examples of the carbon black include Ketjen black, acetylene black, and oxidized carbon black having a pH of 5 or less. More specific examples of the carbon black include “SPECIAL BLACK 350”, “SPECIAL BLACK 100”, “SPECIAL BLACK 250”, “SPECIAL BLACK 5”, “SPECIAL BLACK 4”, “SPECIAL BLACK 4A”, “SPECIAL BLACK 550”, “SPECIAL BLACK 6”, “COLOR BLACK FW200”, “COLOR BLACK FW2”, and “COLOR BLACK FW2V” manufactured by Orion Engineered Carbons S.A. and “MONARCH 880”, “MONARCH 1000”, “MONARCH 1300”, “MONARCH 1400”, “MOGUL-L”, and “REGAL 400R” manufactured by Cabot Corporation.
The average particle size of the conductive agent is, for example, preferably 15 nm or more and 30 nm or less, more preferably 15 nm or more and 25 nm or less, and still more preferably 15 nm or more and 20 nm or less.
The average particle size of the conductive agent is a value measured using a transmission electron microscope (TEM).
The measurement method is as follows.
First, the surface layer is cut using a microtome, and the obtained cross-section is observed with a transmission electron microscope (TEM). The diameter of a circle equivalent to the projected area of each of 50 particles of the conductive agent is obtained as the particle size, and the average value thereof is obtained as the average particle size.
The content of the conductive agent is, for example, preferably 10 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the total mass of the first resin and the second resin.
The surface layer contains a silicon-containing compound, and the content of the silicon-containing compound is, for example, preferably 0.05 parts by mass or more and 0.15 parts by mass or less with respect to 100 parts by mass of the total mass of the first resin and the second resin.
By allowing the surface layer to contain the silicon-containing compound and adjusting the content of the silicon-containing compound to be 0.05 parts by mass or more and 0.15 parts by mass or less with respect to 100 parts by mass of the total mass of the first resin and the second resin, the occurrence of axial color streaks during formation of an image is suppressed, and the contamination resistance of the conductive member and the fogging suppressing effect are improved. The reason for this is presumed to be as follows.
By adjusting the content of the silicon-containing compound to be 0.05 parts by mass or more with respect to 100 parts by mass of the total mass of the first resin and the second resin, the surface roughness of the surface layer appropriately decreases, and the contamination resistance of the conductive member and the fogging suppressing effect are improved. In addition, by adjusting the content of the silicon-containing compound to be 0.15 parts by mass or less with respect to 100 parts by mass of the total mass of the first resin and the second resin, the resistance of the surface layer decreases.
The content of the silicon-containing compound is, for example, more preferably 0.075 parts by mass or more and 0.125 parts by mass or less and still more preferably 0.09 parts by mass or more and 0.11 parts by mass or less with respect to 100 parts by mass of the total mass of the first resin and the second resin.
The content of the silicon-containing compound is measured using an X-ray photoelectron spectrometer (XPS). As the X-ray photoelectron spectrometer, for example, ESCA-3400 (product name, manufactured by Shimadzu Corporation) can be used.
Hereinafter, the procedure of measuring the content of the silicon-containing compound will be described.
Si is detected from peak positions of photoelectrons by X-ray excitation to perform quantification from the area intensity of each of the peak intensities.
In addition, the total mass of the first resin and the second resin is calculated by obtaining a blending ratio between the first resin and the second resin from each of peak ratios of C═O and N—H derived from an amide bond in the first resin and CO derived from a butyral group in the second resin, the amide bond and the butyral group being detected by Fourier-transform infrared spectroscopy (FT-IR). As the FT-IR spectrometer, for example, IR Spirit (product name, manufactured by Shimadzu Corporation) can be used.
Examples of the silicon-containing compound include: silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, or phenylmethylpolysiloxane; and modified silicone oils such as polyether modified polysiloxane, amino modified polysiloxane, epoxy modified polysiloxane, carboxyl modified polysiloxane, carbinol modified polysiloxane, fluorine modified polysiloxane, methacryl modified polysiloxane, mercapto modified polysiloxane, or phenol modified polysiloxane.
From the viewpoint of compatibility, as the silicon-containing compound, for example, polyether modified polysiloxane is preferable.
Distance R Between Island Portions and Radius r of Island Portion
In the conductive member according to the present exemplary embodiment, the distance R between the island portions and the radius r of the island portion in the cross-section of the surface layer satisfy the following Expression (1-1), and satisfy, for example, preferably the following Expression (1-2) and more preferably the following Expression (1-3).
−0.20≤R−2r≤0.40 Expression (1-1):
−0.10≤R−2r≤0.20 Expression (1-2):
−0.10≤R−2r≤0 Expression (1-3):
By allowing the distance R between the island portions and the radius r of the island portion satisfy Expression (1-2), the occurrence of axial color streaks during formation of an image is further suppressed. The reason for this is presumed to be that the distance between the island portions further decreases, the area of a conductive path in the surface layer is likely to further increase, and the resistance of the surface layer further decreases.
In the conductive member according to the present exemplary embodiment, the distance R between the island portions and the radius r of the island portion satisfy Expression (1-2), and the radius r of the island portion is, for example, preferably 0.15 μm or more and 0.25 μm or less, more preferably 0.16 μm or more and 0.24 μm or less, and still more preferably 0.17 μm or more and 0.23 μm or less.
By allowing the distance R between the island portions and the radius r of the island portion satisfy Expression (1-2) and allowing the radius r of the island portion to be 0.15 μm or more and 0.25 μm or less, the occurrence of axial color streaks during formation of an image is further suppressed. The reason for this is presumed to be as follows.
By allowing the radius r of the island portion to be 0.15 μm or more, the area of the island portion increases. In addition, by allowing the distance R between the island portions and the radius r of the island portion satisfy Expression (1-2), the distance between the large island portions is likely to decrease, and the amount of a conductive path is likely to further increase.
In addition, by allowing the radius r of the island portion to be 0.25 μm or less and allowing the distance R between the island portions and the radius r of the island portion satisfy Expression (1-2), the occupancy of the island portion is excessively high, and the island portion is likely to be dispersed and present in the surface layer in a substantially uniform state.
As a result, the reason for this is presumed to be that the resistance of the surface layer is reduced such that the occurrence of axial color streaks during formation of an image is further suppressed.
The distance R between the island portions and the radius r of the island portion are calculated as follows.
A cut sample of the surface layer cut in a thickness direction using a cryomicrotome method is prepared. In the cut sample, a cut surface of the surface layer cut using a cryomicrotome method is observed with a scanning electron microscope. Any 30 island portions in a 12 μm×9 μm square region including the sea portion and the island portion are selected (in this case, the island portions are selected such that a standard deviation of the areas of the cut surfaces of the island portions is 1 σ or less).
The radius of a circle having the same area as each of the areas of the cut surfaces of the island portions is calculated. This arithmetic mean value of the radii is calculated and set as the radius r of the island portion (unit: μm).
The same region as the region in the cut surface of the surface layer observed during the calculation of the radius r of the island portion is observed. A circle (hereinafter, referred to as “specific circle” in this paragraph”) having the same radius as the radius r calculated in the above-described procedure is disposed to overlap the island portion in the region. In this case, the area of a region where the island portion and the specific circle overlap each other is maximized. One specific circle is selected and used as a basic specific circle. Among specific circles adjacent to the basic specific circle, one specific circle adjacent to the basic specific circle is specified such that the distance between the center of the basic specific circle and the center of the specific circle is the shortest, and this specific circle is set as the adjacent specific circle. “The distance between the center of the basic specific circle and the center of the adjacent specific circle” is calculated. While changing the basic specific circle, “the distance between the center of the basic specific circle and the center of the adjacent specific circle” is calculated ten times in total through the same procedure. The arithmetic mean value of the calculated values of “the distance between the center of the basic specific circle and the center of the adjacent specific circle” is calculated and set as the distance R between the island portions (unit:
Here, in a case where the observed cut surface of the surface layer includes an island portion having an area that is more than or equal to 1.7 times the area of the specific circle, the island portion is determined to be a portion where a plurality of island portions overlap each other. In this case, in a case where the distance R between the island portions is calculated, a plurality of specific circles are disposed in the contour of the island portion having an area that is more than or equal to 1.7 times the area of the specific circle, and the distance R between the island portions is calculated through the above-described procedure. The plurality of specific circles are disposed such that the area of the region where the specific circles overlap each other is minimized and the area of a region where the island portion and the specific circle overlap each other is maximized.
Thickness of Surface Layer
The thickness of the surface layer is, for example, preferably 3 μm or more and 25 μm or less, more preferably 5 μm or more and 20 μm or less, and still more preferably 6 μm or more and 15 μm or less.
The thickness of the surface layer is measured by cutting the surface layer in the thickness direction and observing the obtained cross-section with an optical microscope.
Physical Property Values of Conductive Member
Resistance Z
In the conductive member according to the present exemplary embodiment, a resistance Z measured using an impedance method is, for example, preferably 4.5×105Ω or lower, more preferably 4.0×105Ω or lower, and still more preferably 3.5×105Ω or lower.
By adjusting the resistance Z measured using an impedance method to be 4.5×105Ω or lower, the flow of a current in the entire conductive member is facilitated. Therefore, the occurrence of axial color streaks during formation of an image is further suppressed.
The procedure of measuring the resistance Z is as follows.
SI 1260 impedance/gain-phase analyzer (manufactured by Toyo Corporation) is used as a power supply and ammeter, and 1296 dielectric interface (manufactured by Toyo Corporation) is used as a current amplifier.
By using the substrate in the sample (conductive member) for the impedance measurement as a cathode and using an aluminum plate having a width of 1.5 cm that is wound once around the surface of the conductive member as an anode, an AC voltage of 1 Vp-p is applied from a high frequency side in a range from 1 MHz to 1 mHz, and the resistance Z of each of the samples is measured using an AC impedance method.
Surface Roughness Rz In the conductive member according to the present exemplary embodiment, the surface roughness Rz of the outer peripheral surface of the surface layer is, for example, preferably 6.0 μm or less, more preferably 3.0 μm or more and 5.5 μm or less, and still more preferably 3.5 μm or more and 5.0 μm or less.
By adjusting the surface roughness Rz to be 6.0 μm or less, the conductive member in which the occurrence of axial color streaks during formation of an image is suppressed and the occurrence of fogging is suppressed can be obtained. The reason for this is presumed to be as follows.
As described above, in the conductive member according to the present exemplary embodiment, by allowing the distance R between the island portions and the radius r of the island portion satisfy Expression (1-1), the occurrence of axial color streaks during formation of an image is suppressed. By adjusting the surface roughness Rz to be 6.0 μm or less, an image carrier can be charged to a state in a more uniform state. As a result, the occurrence of fogging is suppressed.
The measurement of the surface roughness Rz is performed on the outer peripheral surface of the surface layer as a measurement target using a surface roughness meter SURFCOM 1400A (manufactured by Tokyo Seimitsu Co., Ltd.). The measurement is performed according to JIS B 0601-1994 under measurement conditions of evaluation length Ln: 4 mm, reference length L: 0.8 mm, and cut-off length: 0.8 mm.
Method of Manufacturing Conductive Member
One example of a method of manufacturing the conductive member according to the present exemplary embodiment will be described below.
A roll-shaped member in which the elastic layer is provided on an outer peripheral surface of a cylindrical or columnar substrate is prepared. A method of manufacturing the roll-shaped member is not particularly limited. For example, a method of winding a mixture containing a rubber material and further containing a conductive agent and other additives around the substrate and heating and vulcanizing the mixture to form the elastic layer can be used.
A method of providing the surface layer on the outer peripheral surface of the elastic layer is not particularly limited, and it is preferable that a dispersion liquid in which the first resin, the second resin, and the conductive agent are dissolved and dispersed in a solvent is applied to the outer peripheral surface of the elastic layer and the applied dispersion liquid is dried and provided. Examples of a method of applying the dispersion liquid include a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method.
From the viewpoint of easily obtaining the conductive member in which the distance R between the island portions and the radius r of the island portion in the cross-section of the surface layer satisfy Expression (1-1), the dispersion liquid that is applied to the outer peripheral surface of the elastic layer in a case where the surface layer is provided is, for example, preferably a dispersion liquid (hereinafter, also referred to as “specific dispersion”) in which the first resin, the second resin, the conductive agent, and the silicon-containing compound are dissolved and dispersed in the solvent.
The content of the silicon-containing compound in the specific dispersion is preferably, for example, 0.1 mass % or more and 3 mass % or less with respect to the total mass of the first resin and the second resin.
Use of Conductive Member
The conductive member according to the present exemplary embodiment is used for, for example, a charging roll for charging a surface of the image carrier in an electrophotographic copier, an electrostatic printer, or the like, a transfer roll for transferring a toner image formed on the image carrier to a transfer medium, a toner transport roll for transporting toner to the image carrier, a conductive roll for power feeding or driving in combination with a conductive belt that electrostatically transports paper, or a cleaning roll for removing toner on the image carrier. In addition, in an ink jet type image forming apparatus, for example, a charging roll for charging an intermediate transfer medium before discharging ink from an ink jet head is used.
Hereinabove, the configuration of the conductive member that is the roll-shaped member is described as the conductive member according to the present exemplary embodiment. However, the conductive member according to the present exemplary embodiment is not limited to this configuration and may be an endless belt-shaped member or a sheet-shaped member.
In addition The conductive member according to the present exemplary embodiment may have a configuration in which, for example, an adhesive layer (primer layer) that is provided between the substrate and the elastic layer, a resistance adjusting layer or a transition preventing layer that is provided between the elastic layer and the surface layer, or a coating layer (protective layer) that is provided on an outer side (outer surface) of the surface layer is provided.
Charging Device, Image Forming Apparatus, and Process Cartridge
A charging device according to the present exemplary embodiment includes the conductive member according to the present exemplary embodiment.
It is preferable that the charging device according to the present exemplary embodiment includes, for example, the conductive member according to the present exemplary embodiment, in which an image carrier is charged using a contact charging method.
A contact width of the conductive member with the image carrier in a circumferential direction (that is, a width of the conductive member in the circumferential direction in a region where the image carrier and the conductive member are in contact with each other) is not particularly limited and is, for example, in a range of 0.5 mm or more and 5 mm or less and preferably in a range of 1 mm or more and 3 mm or less.
A process cartridge according to the present exemplary embodiment includes, for example, a charging device that is attached to and detached from an image forming apparatus having a configuration described below and charges a surface of the image carrier. As the charging device, the charging device according to the present exemplary embodiment is applied.
Optionally, the process cartridge according to the present exemplary embodiment may further include, for example, at least one kind selected from the group consisting of an image carrier, an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the image carrier, a developing device that develops the latent image formed on the surface of the image carrier with toner to form a toner image, a transfer device that transfers the toner image formed on the surface of the image carrier to a recording medium, and a cleaning device that cleans the surface of the image carrier.
The image forming apparatus according to the present exemplary embodiment includes: an image carrier; a charging device that charges a surface of the image carrier; an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the image carrier; a developing device that develops the electrostatic latent image formed on the surface of the image carrier with a developer containing toner to form a toner image; and a transfer device that transfers the toner image to a surface of a recording medium. As the charging device, the charging device according to the present exemplary embodiment is applied.
Next, the image forming apparatus and the process cartridge according to the present exemplary embodiment will be described with reference to the drawings.
As shown in
The image forming portion 214 includes: image forming units 222Y, 222M, 222C, and 222K (hereinafter referred to as “222Y to 222K”) that form toner images of colors including yellow (Y), magenta (M), cyan (C), and black (K), respectively; an intermediate transfer belt 224 (an example of a transfer target) to which the toner images formed by the image forming units 222Y to 222K are transferred; a first transfer roll 226 (an example of a transfer roll) that transfers the toner images formed by the image forming units 222Y to 222K to the intermediate transfer belt 224; and a second transfer roll 228 (an example of a transfer member) that transfers the toner images transferred to the intermediate transfer belt 224 by the first transfer roll 226 from the intermediate transfer belt 224 to the recording medium P. The image forming unit 214 is not limited to the above-described configuration and may adopt another configuration as long as an image can be formed on the recording medium P (an example of a transfer target).
Here, a unit consisting of the intermediate transfer belt 224, the first transfer roll 226, and the second transfer roll 228 corresponds to an example of the transfer device. This unit may be configured as a cartridge (process cartridge).
The image forming units 222Y to 222K are disposed side by side in a center portion in a vertical direction of the image forming apparatus 210 in a state where the image forming units 222Y to 222K are inclined with respect to a horizontal direction. In addition, each of the image forming units 222Y to 222K includes a photoreceptor 232 (an example of the image carrier) that rotates in one direction (for example, a clockwise direction in
In the vicinity of each of the photoreceptors 232, in order from the upstream side in the rotation direction of the photoreceptor 232, a charging device 223 including a charging roll 223A (an example of a charging member) that charges the photoreceptor 232, an exposure device 236 (an example of the electrostatic latent image forming device) that exposes the photoreceptor 232 charged by the charging device 223 to form an electrostatic latent image on the photoreceptor 232, a developing device 238 that develops the latent image formed on the photoreceptor 232 by the exposure device 236 to form a toner image, and a removal member (for example, a cleaning blade) 240 that comes into contact with the photoreceptor 232 and removes toner remaining on the photoreceptor 232 are provided.
Here, the photoreceptor 232, the charging device 223, and the exposure device 236, the developing device 238, and the removal member 240 are integrally held by a housing (case) 222A to configure a cartridge (process cartridge).
As the exposure device 236, a self-scanning LED print head is applied. The exposure device 236 may be an optical exposure device that exposes the photoreceptor 232 from a light source through a polygon mirror.
The exposure device 236 forms a latent image based on an image signal transmitted from the controller 220. Examples of the image signal transmitted from the controller 220 include an image signal acquired from an external device by the controller 220.
The developing device 238 includes: a developer supply member 238A that supplies a developer to the photoreceptor 232; and a plurality of transport members 238B that transport the developer given to the developer supply member 238A while agitating the developer.
The intermediate transfer belt 224 is formed in an annular shape and is disposed above the image forming units 222Y to 222K. On an inner peripheral side of the intermediate transfer belt 224, winding rolls 242 and 244 around which the intermediate transfer belt 224 is wound are provided. Any one of the winding rolls 242 and 244 rotates such that intermediate transfer belt 224 circulates and moves (rotates) in one direction (for example, a counterclockwise direction in
The first transfer roll 226 faces the photoreceptor 232 with the intermediate transfer belt 224 interposed therebetween. A position between the first transfer roll 226 and the photoreceptor 232 is a first transfer position at which the toner image formed on the photoreceptor 232 is transferred to the intermediate transfer belt 224.
The second transfer roll 228 faces the winding roll 242 with the intermediate transfer belt 224 interposed therebetween. A position between the second transfer roll 228 and the winding roll 242 is a second transfer position at which the toner image transferred to the intermediate transfer belt 224 is transferred to the recording medium P.
In the transport portion 216, a feed roll 246 that feeds the recording medium P accommodated in the accommodation portion 212, a transport path 248 through which the recording medium P fed by the feed roll 246 is transported, and a plurality of transport rolls 250 that are provided along the transport path 248 and transport the recording medium P fed by the feed roll 246 to the second transfer position are provided.
A fixing device 260 that fixes the toner image formed on the recording medium P by the image forming unit 214 to the recording medium P is provided downstream of the second transfer position in the transport direction.
In the fixing device 260, a heating roll 264 that heats the image on the recording medium P and a pressurization roll 266 that is an example of a pressurization member are provided. In the heating roll 264, a heating source 264B is provided.
A discharge roll 252 that discharges the recording medium P to which the toner image is fixed to the discharge portion 218 is provided downstream of the fixing device 260 in the transport direction.
Next, in the image forming apparatus 210, an image forming operation of forming an image on the recording medium P will be described.
In the image forming apparatus 210, the recording medium P transported from the accommodation portion 212 to the feed roll 246 is transported to the second transfer position by the plurality of transport rolls 250.
On the other hand, in each of the image forming units 222Y to 222K, the photoreceptor 232 charged by the charging device 223 is exposed by the exposure device 236 to form a latent image on the photoreceptor 232. The latent image is developed by the developing device 238 to form a toner image on the photoreceptor 232. The toner images of the colors formed by the image forming units 222Y to 222K overlap each other on the intermediate transfer belt 224 at the first transfer position such that a color image is formed. The color image formed on the intermediate transfer belt 224 is transferred to the recording medium P at the second transfer position.
The recording medium P to which the toner image is transferred is transported to the fixing device 260, and the transferred toner image is fixed by the fixing device 260. The recording medium P to which the toner image is fixed is discharged to the discharge portion 218 by the discharge roll 252. As described above, the series of image forming operations are performed.
The image forming apparatus 210 according to the present exemplary embodiment is not limited to the above-described configuration. For example, well-known image forming apparatus such as a direct transfer type image forming apparatus that directly transfers the toner image formed on each of the photoreceptors 232 of the image forming units 222Y to 222K to the recording medium P may be adopted.
Hereinafter, Examples of the present invention will be described, but the present invention is not limited to these Examples. In the following description, unless specified otherwise, “part(s)” and “%” represent “part(s) by mass” and “mass %”.
Formation of Elastic Layer
15 parts by mass of a conductive agent (carbon black, ASAHI THERMAL manufactured by Asahi Carbon Co., Ltd.), 1 part by mass of a vulcanizing agent (sulfur, 200-mesh, manufactured by Tsurumi Chemical Industry Co., Ltd.) as an additive to be blended in the elastic layer, and 2.0 parts by mass of a vulcanization accelerator (NOCCELER DM, manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.) as another additive to be blended in the elastic layer are added to 100 parts by mass of an elastic material (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber) to obtain a mixture, and the mixture is kneaded in an open roll to obtain a composition for forming an elastic layer. The composition for forming an elastic layer is wound around an outer peripheral surface of a shaft (substrate) having a diameter of 8 mm formed of SUS 303 using a press forming machine through an adhesive layer, is put into a furnace at a temperature of 180° C., and is heated for 30 minutes to form an elastic layer having a thickness of 3.5 mm on the shaft. The outer peripheral surface of the elastic layer is polished to obtain a conductive elastic roll having a diameter of 14 mm that includes the elastic layer having a thickness of 3.0 mm.
Formation of Surface Layer
15 parts by mass of a composition (hereinafter, referred to as “specific composition”) consisting of 76 parts by mass of a polyamide resin (N-methoxymethylated nylon, manufactured by Nagase ChemteX Corporation/F30K) as a first resin, 24 parts by mass of a polyvinyl butyral resin (S-LEC BL-1/manufactured by Sekisui Chemical Co., Ltd.) as a second resin, 13 parts by mass of carbon black (MONARCH 1000/manufactured by Cabot Corporation) as a conductive agent, 10 parts by mass of a porous polyamide filler (ORGASOL 2001 UD NAT1/manufactured by Arkema S.A.), 1.0 part by mass of an acid catalyst (NACURE 4167/manufactured by King Industries, Inc.), and 0.025 parts by mass of polyether modified polysiloxane (BYK 307/manufactured by BYK) as a silicon-containing compound is diluted with 85 parts by mass of methanol and is dispersed with a bead mill to obtain a dispersion liquid. The outer peripheral surface of the elastic layer of the obtained conductive elastic roll is dipped in the obtained dispersion liquid, is heated at 140° C. for 30 minutes for crosslinking, and is dried to form a surface layer having a thickness of 10 μm. As a result, a conductive member is obtained.
A conductive member according to each of examples is obtained through the same procedure as Example 1, except that the composition of the specific composition in (Formation of Surface Layer) is changed as shown in Table 1.
Abbreviations in Table 1 are as described below.
First Resin
Second Resin
Conductive Agent
Acid Catalyst
Silicon-Containing Compound
Evaluation
In the conductive member obtained in each of the examples, the distance R between the island portions, the radius r of the island portion, the resistance Z, the surface roughness Rz, and the content of the silicon-containing compound with respect to the total mass of the surface layer are measured according to the above-described procedure, and the results thereof are shown in Table 2.
Color Streak
The conductive member obtained in Example or Comparative Example is incorporated into a modified machine of an image forming apparatus (DocuCentre-V C7776, manufactured by Fujifilm Business Innovation Corporation), and 5000 A4 images having an image density of 30% are printed under conditions of 28° C. and 85% RH. The level of color streaks that occur after printing 5000 sheets and extend in the axial direction of the photoreceptor is evaluated based on G0 to G3. G0 to G2 are levels where there are no problems in use. Table 2 shows the evaluation results.
G0: the occurrence of color streaks extending in the axial direction of the photoreceptor is not recognized.
G0.5: the number of color streaks extending in the axial direction of the photoreceptor is 1 or less.
G1: the number of color streaks extending in the axial direction of the photoreceptor is 2 or more and 4 or less.
G1.5: the number of color streaks extending in the axial direction of the photoreceptor is 5 or more and 7 or less.
G2: the number of color streaks extending in the axial direction of the photoreceptor is 8 or more and 10 or less.
G2.5: the number of color streaks extending in the axial direction of the photoreceptor is 11 or more and 13 or less.
G3: the number of color streaks extending in the axial direction of the photoreceptor is 14 or more.
Fogging
10 blank pages of A4 paper are printed (pages on which an image is not formed are printed) using the above-described image forming apparatus. The 10 printed sheets of paper are observed by visual inspection, and background fogging is evaluated.
The evaluation criteria are as follows. Table 2 shows the evaluation results.
G0: the occurrence of background fogging is not observed at all
G1: a level where the occurrence of background fogging is slightly observed but there are no problems in practice
G2: a level where the occurrence of background fogging having a certain degree of density is observed and there is a problem in practice
Mechanical Strength
In an MIT test, the mechanical strength of the surface layer is evaluated.
The MIT test is performed according to JIS P 8115:2001 (MIT testing method).
Specifically, a strip-shaped test piece (the thickness of the test piece is the thickness of the surface layer) having a width of 15 mm and a length of 200 mm in the circumferential direction is cut out from the surface layer of the conductive member. Opposite ends of the strip-shaped test piece are fixed, a tensile force of 1 kgf is applied to repeatedly bend (fold) the test piece in a horizontal 90° direction using a clamp having a curvature radius R of 0.05 as a support. In this case, in a case where the strip-shaped test piece is fractured, the number of times the test piece is bent is obtained as a folding endurance number, and the strength is evaluated based on the folding endurance number according to the following evaluation criteria.
The MIT test is performed in an environment of a temperature of 22° C. and a humidity of 55% RH.
Table 2 shows the evaluation results.
G0: the folding endurance number is 100000 or more.
G1: the folding endurance number is 50000 or more and less than 100000.
G2: the folding endurance number is 10000 or more and less than 50000.
G3: the folding endurance number is less than 10000.
In Table 2, “Content (mass %) with respect to Total Mass of First Resin and Second Resin” represents the content of the second resin with respect to 100 parts by mass of the total mass of the first resin and the second resin.
It can be seen from the above results that, in the conductive member according to Example, the occurrence of axial color streaks during formation of an image is suppressed.
(((1)))
A conductive member comprising:
−0.20≤R−2r≤0.40. Expression (1-1):
(((2)))
The conductive member according to (((1))), wherein the distance R and the radius r satisfy the following Expression (1-2),
−0.10≤R−2r≤0.20. Expression (1-2):
(((3)))
The conductive member according to (((2))), wherein in Expression (1-2), the radius r of the island portion is 0.15 μm or more and 0.25 μm or less.
(((4)))
The conductive member according to any one of (((1))) to (((3))), wherein a resistance Z measured using an impedance method is 4.5×105Ω or lower.
(((5)))
The conductive member according to (((4))),
(((6)))
The conductive member according to any one of (((1))) to (((5))), wherein a content of the second resin is 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of a total mass of the first resin and the second resin.
(((7)))
The conductive member according to any one of (((1))) to (((6))), wherein the surface layer contains a silicon-containing compound, and
(((8)))
A charging device comprising:
(((9)))
A process cartridge comprising:
(((10)))
An image forming apparatus comprising:
The foregoing description of the present exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-154083 | Sep 2022 | JP | national |
