Laminated member, method for manufacturing a laminated member, component for electrophotography

Abstract

The present invention provides a laminated member with good visibility and resolution of the marked portion, and a method for manufacturing the same. [Solution] A laminated member comprising a base layer, an adhesive layer, and a surface layer in that order, wherein the base layer has a brightness of 15 or less, the surface layer has a visible light transmittance of 60% or more, air bubbles exist between the surface layer and the base layer, and the air bubbles form a mark that is visible from the surface of the laminated member, and a method for manufacturing the same.

Description

[Technical Field]

[0001] This disclosure relates to a laminated member, a method for manufacturing a laminated member, and a component of an electrophotographic image forming apparatus. [Background technology]

[0002] Electrophotographic image forming apparatuses are equipped with electrophotographic components such as rollers (e.g., fixing rollers) and belts (e.g., fixing belts) in which a fluororesin is coated over a rubber layer. To manage individual electrophotographic components, it is preferable to provide a marking area (for example, a string of characters such as a serial number) on the electrophotographic component (hereinafter also referred to as marking). Furthermore, the marking area not only ensures visibility of lot numbers and other markings, but also requires high resolution to read markings with a large amount of information, such as two-dimensional barcodes.

[0003] As a method for marking such electrophotographic components, Patent Document 1 proposes a method in which a rubber layer is marked and then coated with a fluororesin. Specifically, marking is performed by irradiating a reddish-brown rubber layer with laser light. As a result, the marked area turns black, making it easily visible against the surrounding bright reddish-brown color.

[0004] Furthermore, Patent Document 2 proposes a configuration in which deep grooves are formed in the elastic layer and an adhesive layer is poured in to create a difference in brightness between the marked area and the surrounding area, making the marked area easier to see. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2005-338350 [Patent Document 2] Japanese Patent Publication No. 2016-161929 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the inventions described in Patent Documents 1 and 2 have the following problems. As disclosed in Patent Document 1, when a mark is provided on an elastic layer, a dark-colored elastic layer does not provide sufficient contrast between the marked and unmarked areas, leaving room for improvement in visibility. As disclosed in Patent Document 2, when creating deep indentations and pouring in an adhesive layer, the adhesive layer will not flow into the indentations unless there is a certain width to the indentations. Therefore, it is necessary to make the indentation width somewhat large, and there was room for improvement in the resolution of the mark formed as a result. This disclosure was made in view of the above issues. [Means for solving the problem]

[0007] In other words, a laminated member according to one aspect of the present disclosure is a laminated member in which a base layer, an adhesive layer, and a surface layer are laminated in this order, wherein the base layer has a brightness of 15 or less, the surface layer has a visible light transmittance of 60% or more, air bubbles exist between the surface layer and the base layer, and the air bubbles form a mark that is visible from the surface of the laminated member.

[0008] Furthermore, a method for manufacturing a laminated member according to another aspect of this disclosure is a method for manufacturing a laminated member having a mark portion visible from the surface, characterized in that a pre-treated laminated member having a base layer with a brightness of 15 or less, an adhesive layer, and a surface layer with a visible light transmittance of 60% or more laminated in that order is irradiated with laser light from the surface layer side to create bubbles between the base layer and the surface layer, thereby forming the mark portion.

[0009] Furthermore, an electrophotographic component according to yet another aspect of the present disclosure is a cylindrical electrophotographic component comprising a laminated structure in which an elastic layer, an adhesive layer, and a surface layer are laminated in that order, wherein the elastic layer has a brightness of 15 or less, the surface layer has a visible light transmittance of 60% or more, and air bubbles exist between the surface layer and the elastic layer, and the air bubbles form a mark portion visible from the surface of the laminated structure. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a laminated member having good visibility and resolution of a mark portion, a method for manufacturing the laminated member, and an electrophotographic member having good visibility and resolution of the mark portion.

Brief Description of the Drawings

[0011] [Figure 1] It is a schematic cross-sectional view of an image forming apparatus according to the present disclosure. [Figure 2] It is a schematic cross-sectional view of a fixing device according to the present disclosure. [Figure 3] It is a schematic view of a fixing belt according to the present disclosure. [Figure 4] It is a schematic view of a fixing belt according to the present disclosure. [Figure 5] It is a schematic view of a coating apparatus by a ring coating method in a fixing belt elastic layer forming step according to the present disclosure. [Figure 6] It is a schematic view showing a manufacturing process of a fixing belt according to the present disclosure, (a) shows a process from rubber coating to adhesive application, and (b) shows a process from tube insertion to cutting to the product length. [Figure 7] It is a perspective view of a jig for evaluating the pressure resistance durability of a mark portion of a fixing belt according to the present disclosure.

Embodiments for Carrying Out the Invention

[0012] The laminated member according to the present disclosure is a laminated member in which a base layer, an adhesive layer, and a surface layer are laminated in this order. In the laminated member according to the present disclosure, the base layer has a lightness of 15 or less, and the surface layer has a visible light transmittance of 60% or more. Further, in the laminated member according to the present disclosure, bubbles are present between the surface layer and the base layer, and the bubbles form a mark portion visible from the surface of the laminated member.

[0013] In the following description, the laminated member relating to this disclosure will be explained in detail using an electrophotographic member, specifically a fixing belt used in a fixing device mounted on an electrophotographic image forming apparatus, as an example, but the invention is not limited to such an example. Furthermore, within the scope of the concept of the present invention, various configurations can be replaced with other configurations.

[0014] First, I will explain the overall configuration of the electrophotographic image forming apparatus (hereinafter simply referred to as the image forming apparatus).

[0015] (1) Image forming apparatus Figure 1 is a schematic cross-sectional view of an image forming apparatus. The photoreceptor (image carrier) 101 is rotated at a predetermined process speed (peripheral speed) in the direction of the arrow. As an apparatus for forming a toner image using an electrophotographic process, a charging device 102, a laser light source 110, a laser optical system 109, and a developing device 104 (104Y~104K) are arranged around the photoreceptor 101. A cleaning device 107 is also arranged around the photoreceptor 101.

[0016] Next, we will explain the flow of the electrophotographic process. The photoreceptor 101 is uniformly charged to a predetermined polarity (negative polarity in this example) by a charging roller 102, which is a charging device. Next, the charged photoreceptor 101 is irradiated (image exposure process) by laser light 103 emitted from the laser light source 110 via the laser optical system 109 based on the input image information (information of the original image).

[0017] The laser light source 110 emits a modulated (on / off) laser beam 103 based on the image information to scan and expose the photoreceptor 101. As a result, an electrostatic latent image corresponding to the image information is formed on the photoreceptor 101. Then, the electrostatic latent image formed on the photoreceptor 101 is made visible using toner by the developing device 104.

[0018] Specifically, a yellow toner image is formed by the developing device 104Y, and this yellow toner image is first transferred from the photoreceptor 101 to the intermediate transfer body 105 in the primary transfer unit T1. After the primary transfer, any toner remaining on the photoreceptor 101 is cleaned by the cleaning device 107.

[0019] The process cycle of charging, exposure, development, primary transfer, and cleaning described above is repeated in the same manner to form the magenta toner image (developer 104M is activated), the cyan toner image (developer 104C is activated), and the black toner image (developer 104K is activated).

[0020] In this manner, the four toner images transferred sequentially onto the intermediate transfer body 105 are transferred collectively to the recording material in the secondary transfer section T2. ​​At this time, a positive voltage is applied to the transfer roller 106 positioned opposite the intermediate transfer body 105. After secondary transfer, any toner remaining on the intermediate transfer body 105 is cleaned by the cleaning device 108.

[0021] Furthermore, the cleaning device 108 is designed to be able to move toward and away from the intermediate transfer body 105, and is configured to be in contact with the intermediate transfer body 105 only when cleaning the intermediate transfer body 105. Similarly, the transfer roller 106 is also designed to be able to move toward and away from the intermediate transfer body 105, and is configured to be in contact with the intermediate transfer body 105 only during secondary transfer.

[0022] The recording material that has passed through the secondary transfer section T2 is then subjected to heat and pressure by the fixing belt 1 and pressure roller 6 (Figure 2) of the fixing device (image heating device) 100, and undergoes a fixing process (image heating process) of the toner image t (Figure 2) supported thereon. The recording material that has undergone the fixing process is then discharged from the machine, and the series of image forming operations is completed. In this example, the fixing belt 1 provided in the fixing device 100 is the electrophotographic component according to this disclosure.

[0023] (2) Fixing device Figure 2 is a schematic cross-sectional view of the fixing device 100. The endless fixing belt (fixing rotating body) 1 is used in this disclosure as a cylindrical electrophotographic component.

[0024] The pressure roller (pressure rotating body) 6 is a component for forming a nip portion 14 with the fixing belt 1. This pressure roller 6 has a multilayer structure in which a silicone rubber elastic layer approximately 3 mm thick and a tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA) resin tube approximately 50 μm thick are sequentially laminated on a metal core. Both ends of the core of this pressure roller 6 in the longitudinal direction are rotatably supported on the apparatus frame 13.

[0025] When the pressure roller 6 is driven to rotate in the direction of the arrow by the drive motor, the fixing belt 1, which is in contact with it, rotates in accordance with the pressure roller 6. In addition, the fixing belt 1 has a lubricant applied to its inner surface, ensuring smooth sliding between it and the holder 4.

[0026] The fixing heater 2 is a component for heating the recording material P via the fixing belt 1. This fixing heater 2 has an alumina substrate and a resistance heating element formed by applying a conductive paste containing a silver-palladium alloy to the alumina substrate in a film about 10 μm thick using a screen printing method. The fixing heater 2 is further made a ceramic heater with a glass coating of pressure-resistant glass applied to the resistance heating element. This fixing heater 2 also functions as a pressing member that presses the fixing belt 1 toward the pressure roller 6.

[0027] The holder 4 is a component that holds the fixing heater 2 and is made of a highly heat-resistant liquid crystal polymer resin. The metal stay 5 is a component that backs up the holder 4, and both ends of its longitudinal direction are biased against the pressure roller 6 by a pressurizing mechanism with a force of, for example, a total pressure of 290 N (29 kgf).

[0028] The temperature sensor 3 is a component that detects the temperature of the fuser heater 2 and is connected to the control unit (CPU) 10 via the A / D converter 9. The temperature sensor 3 outputs a temperature detection signal to the control unit 10. The control unit 10, on the other hand, samples the output from the temperature sensor 3 at a predetermined period and uses the resulting temperature information to control the temperature. In other words, the control unit 10 plays the role of controlling the power supply to the fuser heater 2 via the heater drive circuit 11 so that the temperature of the fuser heater 2 reaches the target temperature, based on the output of the temperature sensor 3.

[0029] Guide 7 is a component that guides the recording material P toward the nip portion 14. The transport roller pair 8 is a component that transports the recording material P immediately after the fixing process.

[0030] (2-1) Fixing belt Figure 3 is a schematic diagram showing the anchoring belt 1. The fixing belt 1 is a cylindrical electrophotographic member according to the present disclosure, and includes a laminated structure in which an elastic layer 1d, an adhesive layer 1e, and a surface layer 1f are laminated in this order. The elastic layer 1d is a layer corresponding to the base layer in the laminated member according to the present disclosure.

[0031] The fixing belt 1 also has a cylindrical base 1b and an inner sliding layer 1a disposed on the inner circumferential surface of the cylindrical base 1b. Here, the inner sliding layer 1a is provided to improve sliding performance with respect to the fixing heater 2. However, if there is no particular need to improve sliding performance, the inner sliding layer 1a may be omitted.

[0032] The elastic layer (hereinafter also referred to as the rubber layer or silicone rubber elastic layer) 1d is arranged on the outer surface of the cylindrical substrate 1b via a primer layer 1c. The surface layer (hereinafter also referred to as the fluororesin layer or release layer) 1f is arranged on the outer surface of the rubber layer 1d via a white adhesive layer 1e.

[0033] In the fixing belt 1, air bubbles exist between the surface layer 1f and the rubber layer 1d, and these air bubbles form a mark portion 1L that is visible from the surface of the electrophotographic component (fixing belt 1) as a laminated member. This mark portion 1L consists of characters, symbols, a two-dimensional barcode, etc., for managing the fixing belt 1. Specifically, in this example, "Lot:ABC" and its two-dimensional barcode (DataMarix) are engraved on it.

[0034] Furthermore, this mark section 1L is not limited to the examples mentioned above; it can also be used to indicate any intention or instruction to the operator or assembler, such as an arrow indicating the direction of assembly during manufacturing or assembly, or a diagram showing the assembly procedure. The following describes each layer of the anchoring belt 1 in detail.

[0035] (2-1-1) Cylindrical substrate The material of the cylindrical substrate 1b is not particularly limited, and known materials used as base layers for fixing members such as fixing films can be used. For example, the material of the cylindrical substrate 1b can be metals and alloys such as aluminum, iron, stainless steel, and nickel, as well as heat-resistant resins such as polyimide. The thickness is not particularly limited, but from the viewpoint of strength, flexibility, and heat capacity, it is preferably 20 μm to 100 μm.

[0036] The outer surface of the cylindrical substrate 1b may be surface-treated to provide adhesion to the elastic layer 1d. Surface treatment can include one or more combinations of physical treatments such as blasting, lapping, and polishing, or chemical treatments such as oxidation, coupling agent treatment, and primer treatment.

[0037] To improve the adhesion between the cylindrical substrate 1b and the elastic layer 1d, it is preferable to apply a primer treatment to the surface of the cylindrical substrate 1b. Examples of primers used for the primer treatment include paints in which a silane coupling agent, a silicone polymer, methyl siloxane hydrogenation, an alkoxysilane, a reaction-accelerating catalyst, and a coloring agent such as red iron oxide are appropriately blended and dispersed in an organic solvent. The primer can be appropriately selected depending on the material of the cylindrical substrate 1b, the type of elastic layer 1d, or the form of the crosslinking reaction. In particular, when the elastic layer 1d contains a large amount of unsaturated aliphatic groups, a primer containing hydrosilyl groups is preferably used to impart adhesion through reaction with the unsaturated aliphatic groups.

[0038] Other primers that may be used include those containing alkoxy groups. Commercially available primers can be used. The priming process also includes the step of applying the primer to the outer surface (adhesion surface with the elastic layer) of the cylindrical substrate 1b and drying or firing it.

[0039] (2-1-2) Inner sliding layer Suitable resins for the inner sliding layer 1a include polyimide resin, polyamide-imide resin, and polyetheretherketone resin, which have high durability and high heat resistance. In particular, polyimide resin is preferred for the inner sliding layer 1a in terms of ease of manufacture, heat resistance, elastic modulus, and strength. The polyimide resin is formed from a polyimide precursor solution obtained by reacting an aromatic tetracarboxylic dianhydride or its derivative with an aromatic diamine in approximately equimolar amounts in an organic polar solvent. Specifically, the polyimide precursor solution can be formed by coating the inner surface of a cylindrical substrate 1b, drying, heating, and causing a dehydration and ring-closing reaction.

[0040] As a coating method, the ring coating method can be employed. The cylindrical substrate 1b, which has been coated on the inside, is left to dry in a hot air circulation furnace at 60°C for 30 minutes, for example, and then left to be fired in a hot air circulation furnace at 200°C to 240°C for 10 to 60 minutes, which is a temperature range that does not reduce the fatigue strength of the cylindrical substrate. As a result, a polyimide inner sliding layer can be formed by a dehydration ring-closing reaction.

[0041] (2-1-3-1) Elastic layer The elastic layer 1d is a layer that provides flexibility to the electrophotographic component in order to ensure a fixing nip in a thermal fixing device. Furthermore, when the electrophotographic component is used as a heating component that comes into contact with toner on paper, the elastic layer 1d also functions as a layer that provides flexibility to the surface of the heating component so that it can conform to the irregularities of the paper.

[0042] The elastic layer 1d comprises rubber as a matrix and particles dispersed in the rubber. More specifically, the elastic layer 1d comprises rubber and thermally conductive particles, and is composed of a cured product obtained by curing a composition that contains at least rubber raw materials (base polymer, crosslinking agent, etc.) and thermally conductive particles.

[0043] A silicone rubber composition is preferably used as the composition for forming the elastic layer 1d. Since silicone rubber compositions are mostly liquid, thermally conductive fillers are easily dispersed, and the elasticity of the elastic layer 1d can be easily adjusted by adjusting the degree of crosslinking according to the type and amount of thermally conductive particles added.

[0044] The rubber matrix plays the role of providing elasticity in the elastic layer 1d. From the viewpoint of enabling the elastic layer 1d to exhibit the above-described function, the rubber matrix preferably contains silicone rubber. Silicone rubber is preferable because it has high heat resistance that allows it to maintain flexibility even in environments where the non-paper-feeding region reaches high temperatures of about 240°C. As the silicone rubber, for example, a cured product of addition-curing type liquid silicone rubber described later can be used.

[0045] The liquid silicone rubber composition usually contains the following components (a) to (d): Component (a): A linear organopolysiloxane having an unsaturated aliphatic group Component (b): An organopolysiloxane having active hydrogen bonded to silicon Component (c): A catalyst Component (d): A thermal conductivity filler Hereinafter, each component will be described.

[0046] <Component (a)> The linear organopolysiloxane having an unsaturated aliphatic group is an organopolysiloxane having an unsaturated aliphatic group such as a vinyl group, and examples thereof include the following structural formulas (1) and (2) having a structure in which siloxane bonds are linearly connected.

[0047]

Chemical formula

[0048]

Chemical formula

[0049] In Structural formulas (1) and (2), R 1 and R 3Examples of monovalent unsubstituted or substituted hydrocarbon groups that do not contain unsaturated aliphatic groups that can be represented by include the following groups:

[0050] Examples of unsubstituted hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl groups, and aryl groups such as phenyl groups. Examples of substituted hydrocarbon groups include substituted alkyl groups such as chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, 3-cyanopropyl, and 3-methoxypropyl.

[0051] The organopolysiloxanes shown in structural formulas (1) and (2) have at least one methyl group directly bonded to the silicon atom forming the chain structure. However, because they are easy to synthesize and handle, R 1 and R 3 Preferably, more than 50% of each is a methyl group, and all R 1 and R 3 It is more preferable that the group is a methyl group.

[0052] Furthermore, in structural formulas (1) and (2), R 2 and R 4 Examples of unsaturated aliphatic groups that can be represented include the following groups. Specifically, examples of unsaturated aliphatic groups include vinyl groups, allyl groups, 3-butenyl groups, 4-pentenyl groups, and 5-hexenyl groups. Among these groups, R is chosen because it is easy and inexpensive to synthesize and handle, and crosslinking reactions can be easily carried out with it. 2 and R 4 Preferably, all of these are vinyl groups.

[0053] The viscosity of component (a) is 1000 mm from the viewpoint of moldability. 2 / s or more 20000mm 2 Preferably, it should be less than or equal to / s. 1000mm 2 If the value is lower than / s, it becomes difficult to adjust the hardness required for the elastic layer, 20000mm 2If the viscosity is higher than / s, the surface quality after coating may deteriorate. Viscosity (kinematic viscosity) can be measured using a capillary viscometer, rotational viscometer, etc., in accordance with JIS Z 8803:2011.

[0054] The amount of component (a) is preferably 55% by volume or more from the viewpoint of durability and 70% by volume or less from the viewpoint of heat transfer, based on the liquid silicone rubber composition used to form the elastic layer 1d.

[0055] <Component (b)> Organopolysiloxanes, which have active hydrogen bonded to silicon, react with the unsaturated aliphatic group of component (a) through the action of a catalyst and function as a crosslinking agent to form cured silicone rubber.

[0056] Any organopolysiloxane having a Si-H bond can be used as component (b). In particular, from the viewpoint of reactivity with the unsaturated aliphatic group of component (a), those having an average of 3 or more hydrogen atoms bonded to the silicon atom in one molecule are preferably used.

[0057] Specific examples of component (b) include, for example, the linear organopolysiloxane shown in structural formula (3) below and the cyclic organopolysiloxane shown in structural formula (4) below. [ka] In structural formula (3), m 2 represents an integer greater than or equal to 0, and n 3 This represents an integer greater than or equal to 3, and R 5 Each of these independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group. [ka] In structural formula (4), m 3 represents an integer greater than or equal to 0, and n 4 This represents an integer greater than or equal to 3, and R 6 Each of these independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group.

[0058] R in structural formulas (3) and (4) 5 and R 6 Examples of monovalent unsubstituted or substituted hydrocarbon groups that do not contain unsaturated aliphatic groups that can be represented include R in structural formula (1) above. 1 Similar groups can be cited. Among these, R is chosen because it is easy to synthesize and handle, and excellent heat resistance can be easily obtained. 5 and R 6 Preferably, more than 50% of each is a methyl group, and all R 5 and R 6 It is more preferable that the group is a methyl group.

[0059] <Ingredient (c)> Examples of catalysts used in the formation of silicone rubber include hydrosilylation catalysts to accelerate the curing reaction. Known substances such as platinum compounds and rhodium compounds can be used as hydrosilylation catalysts. The amount of catalyst can be set as appropriate and is not particularly limited.

[0060] <Ingredient (d)> Thermally conductive fillers are selected considering their own thermal conductivity, specific heat capacity, density, particle size, relative permittivity, etc. They are used to improve the heat transfer properties of inorganic materials, especially metals and metal compounds, but from the viewpoint of the heat resistance of the elastic layer 1d, it is preferable to use metallic silicon, silicon carbide, carbon fibers, etc. as the main component, as they contain few ionic impurities (Na+, etc.) in the filler. Heat resistance is particularly important when performing the process of heating the release layer 1f, described later, at a temperature above its melting point to improve the thermal conductivity in the thickness direction and the degree of crystallinity.

[0061] By incorporating component (d) in this way, the silicone rubber is colored, and the brightness (L*) of the rubber layer 1d becomes 15 or less. This lightness (L*) is defined in the CIE Lab (L*a*b* color space). When the differences in L* (lightness), a* (hue on the red-green axis), and b* (hue on the yellow-blue axis) between objects are denoted as ΔL*, Δa*, and Δb*, respectively, the color difference is defined as (ΔL*² + Δa*² + Δb*²)¹ / ². A larger color difference tends to result in better visibility. Furthermore, this lightness (L*) can be measured using a Personal Image Analysis System (PIAS) manufactured by Quality Engineering Associates (QEA).

[0062] (2-1-3-2) Method of coating the rubber layer Figure 5 shows an apparatus for coating a silicone rubber elastic layer 1d onto a cylindrical substrate 1b (on the substrate). In this example, the ring coating method is used. This corresponds to the first step in Figure 6(a).

[0063] An addition-curing silicone rubber composition, which is a mixture of addition-curing silicone rubber and an inorganic filler, is filled into a cylinder pump 57 by turning on the first motor 58a. The addition-curing silicone rubber composition filled into this pump 57 is pumped towards the coating head 54 via a pressure feeding tube 56. The addition-curing silicone rubber composition is then coated onto the outer surface of the cylindrical substrate 1b from a coating liquid supply nozzle 53 located inside the coating head 54.

[0064] Here, the cylindrical base 1b is integrated with the cylindrical core 51 inserted inside. In other words, the cylindrical base 1b is rotated by the second motor 58b in parallel with the supply of the coating liquid, thereby rotating the cylindrical core 51. Furthermore, the third motor 58c slides the cylindrical base 1b together with the cylindrical core 51 at a constant speed to the right (Figure 5) by the slider 52. As a result, the addition-curing type silicone rubber composition is coated over the entire surface of the cylindrical base 1b, and a coating film is formed.

[0065] The thickness of this coating can be controlled by the clearance between the coating liquid supply nozzle 53 and the cylindrical substrate 1b, the supply speed of the silicone rubber composition, and the movement speed of the cylindrical substrate 1b. In this example, the clearance between the coating liquid supply nozzle 53 and the cylindrical substrate 1b is set to 300 μm, the supply speed of the silicone rubber composition is set to 2.8 mm / s, and the movement speed of the cylindrical substrate 1b is set to 30 mm / s, resulting in a 250 μm silicone rubber composition layer 55.

[0066] The addition-curing type silicone rubber composition layer 55 formed on the cylindrical substrate 1b can be converted into a silicone rubber elastic layer 1d by heating it in an electric furnace for a certain period of time to allow the crosslinking reaction (curing) to proceed.

[0067] Furthermore, in order to improve the adhesion between the cylindrical substrate 1b and the silicone rubber elastic layer 1d, it is desirable that the cylindrical substrate 1b be pre-treated with a primer (adhesive is applied). The primer (adhesive) used should have better wettability with the cylindrical substrate 1b than with the silicone rubber elastic layer 1d. Examples of suitable primers include hydrosilyl (SiH) silicone primers, vinyl silicone primers, and alkoxy silicone primers. In this example, a silicone primer is used. The thickness of the primer layer 1c should be such that it exhibits adhesive performance while minimizing unevenness, and is preferably between 0.5 μm and 5.0 μm.

[0068] (2-1-4) Adhesive layer The adhesive layer 1e is interposed between the silicone rubber elastic layer 1d and the fluororesin tube, which is the fluororesin layer 1f, and plays a role in fixing them together.

[0069] An adhesive layer 1e is formed by applying an adhesive to the cured silicone rubber elastic layer 1d. This corresponds to the second step in Figure 6(a). Then, the fluororesin tube F is applied to the rubber layer 1d on which the adhesive layer 1e is formed, and the adhesive present between the rubber layer 1d and the fluororesin tube F is removed, so that the thickness of the adhesive layer 1e becomes almost uniform throughout. This removal process corresponds to the seventh step in Figure 6(b).

[0070] The thickness of the adhesive layer 1e after the scraping process is preferably 3 μm or more and 10 μm or less. An addition-curing silicone rubber adhesive can be used as the adhesive constituting the adhesive layer 1e. Specifically, the addition-curing silicone rubber adhesive contains an organopolysiloxane having an unsaturated hydrocarbon group represented by a vinyl group, a hydrogen organopolysiloxane, and a platinum compound as a crosslinking catalyst. It then hardens by an addition reaction.

[0071] As an adhesive that satisfies the above conditions, the addition-curing silicone rubber adhesive "DOW CORNING(R) SE 1819 CV A / B (manufactured by Toray Dow Corning)" can be used.

[0072] (2-1-5) Fluorine-based resin layer In this example, a fluororesin tube is used as the fluororesin layer (release layer) 1f. It is preferable to use tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), polytetrafluoroethylene (PTFE), or tetrafluoroethylene-hexafluoropropylene copolymer (FEP) as the material for the fluororesin tube. In particular, PFA is preferred as the material for the fluororesin tube from the viewpoint of moldability and toner release properties.

[0073] The thickness of the fluororesin layer 1f is preferably 30 μm or less. This is because, when laminated onto the rubber layer 1d, it is possible to maintain the elasticity of the underlying rubber layer 1d and prevent the surface hardness of the fixing belt 1 from becoming too high. The inner surface of the fluororesin tube is preferably treated with sodium, excimer laser, ammonia, etc. in advance to improve adhesion.

[0074] Fluorine-based resin tubes can be manufactured, for example, by extruding molten PFA from a cylindrical die. Such PFA tubes are rapidly cooled during the extrusion process, causing rapid crystallization. As a result, the crystals are oriented in the direction of extrusion, and the degree of crystallinity is low.

[0075] Here, the PFA tube is coated onto the surface of the elastic layer 1d to form a release layer 1f, and then heat treatment is performed at a temperature above the melting point of the PFA constituting the release layer 1f. This relaxes the molecular orientation of the PFA tube, and the molecular chains that were oriented in the extrusion direction become random, thereby improving the thermal conductivity in the thickness direction.

[0076] Furthermore, by controlling the cooling rate after heating is complete, the degree of crystallinity can be increased, and spherulites can be formed on the surface of the release layer 1f.

[0077] The fluororesin layer 1f must have a light transmittance (visible light transmittance) of 60% or higher. This is to avoid hindering the visibility of the mark section 1L located in the lower layer. This light transmittance can be measured using a UV-Vis-NIR spectrophotometer. Furthermore, a light transmittance (visible light transmittance) of 60% or higher means that the transmittance is 60% or higher across the entire wavelength range of 380 nm to 750 nm in the obtained spectral data.

[0078] (2-1-6) Marking process In this example, a marking process using a UV laser is performed from the release layer 1f side to form a mark 1L that can be visually inspected for purposes such as managing the fixing belt 1. This corresponds to the 10th step in Figure 6(b).

[0079] When a UV laser is shone from the side of the release layer 1f onto a component in which the elastic layer 1d and release layer 1f are fixed via the adhesive layer 1e, the UV laser penetrates the release layer 1f and adhesive layer 1e and reacts on the surface of the elastic layer 1d. The energy generated then propagates to the adhesive layer 1e and release layer 1f, destroying the inside of the adhesive layer 1e and release layer 1f, thereby creating a void extending from the adhesive layer 1e to the inside of the release layer 1f. As a result, bubbles are formed between the release layer 1f and the elastic layer 1d along the letters, symbols, two-dimensional barcodes, etc. of the marked area 1L. Visible light that has passed through the release layer 1f is scattered by the bubbles, increasing the contrast difference between the unmarked area and the marked area 1L, thereby improving visibility.

[0080] Furthermore, since UV laser marking generates little heat, it is less likely to cause unevenness, and a high-resolution mark area 1L can be formed. As a result, even when using a low-brightness elastic layer 1d, the visibility of the marked area 1L can be ensured.

[0081] This method offers superior productivity compared to marking methods using blades or inkjet marking, as it eliminates the need to replace consumable parts. Furthermore, unlike marking methods that scratch the outer surface, such as blade marking, or inkjet marking methods that apply ink, it is less susceptible to changes in visibility due to surface wear caused by friction or other factors. Inkjet methods also suffer from the problem of pigment carbonization at high temperatures.

[0082] The size of the bubbles generated by the laser light can be adjusted by controlling the laser's output.

[0083] Figures 4(a) to 4(c) are schematic diagrams illustrating the difference in bubble size generated depending on the laser output level. Of Figures 4(a) to 4(c), Figure 4(a) shows bubbles generated by the lowest laser output level, and Figure 4(c) shows bubbles generated by the highest laser output level. Figure 4(b) shows bubbles generated by laser output levels between those of Figures 4(a) and 4(c).

[0084] As shown in Figures 4(a) to 4(c), the larger the bubbles become as the laser output increases. As mentioned above, when a member consisting of an elastic layer 1d, an adhesive layer 1e, and a release layer 1f is irradiated with laser light from the release layer 1f side, the UV laser reacts on the surface of the elastic layer 1d (Figure 4(a)). Increasing the laser output makes the destruction of the adhesive layer 1e due to this reaction energy more pronounced, and the voids created within the adhesive layer 1e also become more pronounced (Figure 4(b)). If the laser output is increased even further, the destruction caused by the reaction energy from the laser irradiation on the surface of the elastic layer 1d extends from the adhesive layer 1e to the release layer 1f (Figure 4(c)). As a result, the adhesive layer 1e disappears between the end of the bubble created by the destruction that is opposite to the side in contact with the elastic layer 1d and the release layer 1f, and the bubble comes into contact with the release layer 1f.

[0085] In the laminated member according to this disclosure, it is more preferable from the viewpoint of visibility and detail that a portion of the circumferential surface of the bubble is in contact with the release layer 1f, as shown in Figure 4(c). If the bubble remains inside the adhesive layer 1e, the light transmitted through the release layer 1f is absorbed at the surface of the adhesive layer 1e. In contrast, if there is no adhesive layer 1e between the end of the bubble opposite to the side in contact with the elastic layer 1d and the release layer 1f, and a portion of the circumferential surface of the bubble is in contact with the release layer 1f, the light transmitted through the release layer 1f is diffusely reflected by the bubble, making it easier to create contrast, thus improving visibility and detail.

[0086] Confirmation that a portion of the circumferential surface of the air bubble is in contact with the release layer 1f can be confirmed, for example, by preparing a cross-sectional sample of the fixing belt and observing the cross-section under a microscope.

[0087] In this example, the fixing belt is first cut with a sharp knife or scissors, and then a cross-sectional sample is prepared by polishing the cross-section using an ion mill (Hitachi IM-4000). A confocal microscope (Lasertec H1200) is used for cross-sectional observation.

[0088] Another observation method involves measuring the thickness of the release layer 1f in the marked and unmarked areas using a blue laser displacement meter, which can confirm that the bubbles have progressed to the release layer 1f.

[0089] (3) Manufacturing process for fixing belts The manufacturing method for a laminated member having a mark portion visible from the surface, as described in this disclosure, is applied to the manufacture of a fixing belt. Specifically, the manufacturing method for a laminated member according to this disclosure is characterized by forming the mark portion by irradiating the pre-treatment laminated member with laser light from the surface layer side to create bubbles between the base layer and the surface layer. Here, the pre-treatment laminated member is a member in which a base layer with a brightness of 15 or less, an adhesive layer, and a surface layer with a visible light transmittance of 60% or more are laminated in this order.

[0090] Figures 6(a) and (b) show the process for manufacturing a fixing belt. The two steps shown in Figure 6(a) represent the process from coating the rubber layer 1d to applying the adhesive, while the 11 steps shown in Figure 6(b) represent the process from coating the fluororesin tube F to cutting it to the product length.

[0091] The two steps in Figure 6(a) are as described above. Below, we will describe the 11 steps in Figure 6(b) in detail. In this example, a method is used in which the fluororesin tube F is expanded and coated from the outside of the rubber layer 1d (expanded coating method).

[0092] In the first step of Figure 6(b), a fluororesin tube F is placed in a metal expandable K having an inner diameter larger than the outer diameter of a cylindrical base 1b on which rubber layers 1d are laminated, and both ends of the fluororesin tube F in the longitudinal direction are held using retaining members Ku and Kl.

[0093] In the second step, the gap between the outer surface of the fluororesin tube F and the inner surface of the expandable K is made into a vacuum (negative pressure relative to atmospheric pressure). As a result of the vacuum (5 kPa), the fluororesin tube F expands radially, and the outer surface of the fluororesin tube F adheres tightly to the inner surface of the expandable K.

[0094] In the third step, the intermediate product formed in the two steps shown in Figure 6(a), namely the cylindrical substrate 1b with the rubber layer 1d laminated on it, is inserted into the expandable mold K. An addition-curing silicone rubber adhesive is uniformly applied to the outer surface of the rubber layer 1d.

[0095] In the fourth step, a cylindrical base 1b with a rubber layer 1d laminated on it is placed inside the expanded fluororesin tube F, and then the vacuum state (negative pressure relative to atmospheric pressure) in the gap between the outer surface of the fluororesin tube F and the inner surface of the expanded K is released.

[0096] When the vacuum is released, the fluororesin tube F expands to approximately the same size as the outer diameter of the cylindrical substrate 1b on which the rubber layer 1d is laminated, and the fluororesin tube F and the rubber layer 1d become tightly attached to each other.

[0097] In the fifth step, the fluororesin tube F is stretched in its longitudinal direction until it reaches a predetermined elongation ratio. When the fluororesin tube F is stretched, the adhesive interposed between the fluororesin tube F and the rubber layer 1d acts as a lubricant, allowing the fluororesin tube F to stretch smoothly. The longitudinal elongation rate of the fluororesin tube F can be, for example, 8%.

[0098] In this way, by stretching the fluororesin tube F in the longitudinal direction, wrinkles are less likely to form in the fluororesin tube while it is in use in the fixing device, resulting in a highly durable fixing belt.

[0099] In the sixth step, since the fluororesin tube F is acting to return to its original length, it is temporarily fixed by pressing and heating it from the outside with a metal block M containing a heater. The temperature of the metal block M during pressing / heating is, for example, 200°C, and the pressing / heating time is, for example, 20 seconds.

[0100] In the seventh step, any excess lubricant between the rubber layer 1d and the fluororesin layer 1f is scraped off. Through this scraping process, the thickness X (Figure 3) of the adhesive layer 1e is adjusted to be, for example, within the range of 3 μm to 10 μm.

[0101] In the eighth step, the material is heated in an electric furnace for a predetermined time. As a result, the adhesive hardens, forming adhesive layer 1e.

[0102] In the ninth step, the PFA material of the release layer 1f is heat-treated at a temperature above its melting point to relax the molecular orientation of the PFA tube, randomizing the molecular chains that were oriented in the extrusion direction and improving the thermal conductivity in the thickness direction. To heat the entire fixing member, an upright, cylindrical heating cylinder capable of heating to, for example, 330°C or higher is used. A band heater with a thermocouple is installed inside the heating cylinder to control the heating temperature of the fixing member.

[0103] Furthermore, by controlling the cooling rate of the heating cylinder after heating is complete, the degree of crystallization can be increased by controlling the cooling rate of the fixing member. For example, the cooling rate can be controlled by providing an air supply nozzle on the outer circumference of the heating cylinder and adjusting the air flow rate.

[0104] In the subsequent marking process, a UV laser is irradiated from the release layer 1f towards the elastic layer 1d. In this process, the UV laser penetrates the release layer 1f and the adhesive layer 1e and reacts on the surface of the elastic layer 1d. The energy from this reaction propagates to the adhesive layer 1e and the release layer 1f, destroying them and creating voids extending from the adhesive layer 1e to the inside of the release layer 1f. As a result, bubbles are formed between the release layer 1f and the elastic layer 1d along the lines of the letters, symbols, two-dimensional barcodes, etc. of the marked area. Visible light that has passed through the release layer 1f is scattered by these bubbles, increasing the contrast difference between the unmarked area and the marked area 1L, thus improving visibility.

[0105] In the final step, the fixing belt 1 is cut to the desired length. The fixing belt 1 is manufactured through the above process. [Examples]

[0106] The effects of this disclosure will be explained below using examples and comparative examples. <Example 1> (1) Preparation of liquid addition-curing silicone rubber composition First, 98.6 parts by mass of a silicone polymer was prepared as component (a), which has vinyl groups, which are unsaturated aliphatic groups, only at both ends of the molecular chain, and methyl groups as unsubstituted hydrocarbon groups that do not contain any other unsaturated aliphatic groups. This silicone polymer (product name: DMS-V35, manufactured by Gelest, viscosity 5000 mm) 2 From now on, / s will be referred to as "Vi".

[0107] Next, 170 parts by mass of metallic silicon (product name: #350, manufactured by Kinsei Matec Co., Ltd.) was added to Vi as a thermally conductive filler and thoroughly mixed to obtain mixture 1.

[0108] Next, 0.2 parts by mass of 1-ethynyl-1-cyclohexanol (manufactured by Tokyo Chemical Industry Co., Ltd.), a curing retarder, was dissolved in the same mass of toluene as component (d) and added to mixture 1 to obtain mixture 2.

[0109] Next, 0.1 parts by mass of a hydrosilylation catalyst (platinum catalyst: a mixture of 1,3-divinyltetramethyldisiloxane platinum complex, 1,3-divinyltetramethyldisiloxane, and 2-propanol) was added to mixture 2 as component (c) to obtain mixture 3.

[0110] Furthermore, component (b) is a silicone polymer with a linear siloxane skeleton and active hydrogen groups bonded to silicon only in the side chains (product name: HMS-301, manufactured by Gelest, viscosity 30 mm). 2 1.5 parts by mass of (hereinafter referred to as "SiH") was weighed out. This was added to mixture 3 and thoroughly mixed to obtain a liquid addition-curing silicone rubber composition.

[0111] (2) Preparation of fixing belt As a polyimide precursor solution, an N-methyl-2-pyrrolidone solution of a polyimide precursor consisting of 3,3',4,4'-biphenyltetracarboxylic dianhydride and paraphenylenediamine was prepared. This precursor solution was coated onto the inner surface of a cylindrical substrate 1b made of stainless steel (SUS) with an inner diameter of φ24 mm, a thickness of 30 μm, and a length of 400 mm. By firing at 200°C for 20 minutes, imidization was performed, forming an inner sliding layer 1a with a thickness of 15 μm.

[0112] A primer (product name: DY39-051A / B; manufactured by Toray Dow Corning Co., Ltd.) was applied almost uniformly to the outer surface of the cylindrical substrate 1b to a dry weight of 20 mg. After drying the solvent, the primer layer 1c was formed by baking in an electric furnace set to 160°C for 30 minutes.

[0113] The above silicone rubber composition was applied to this primer-treated substrate to a thickness of 250 μm using the ring-coating method. This is referred to as an uncured endless belt.

[0114] The uncured endless belt was heated in an electric furnace at 160°C for 1 minute (primary curing), and then heated in an electric furnace at 200°C for 30 minutes (secondary curing) to cure the silicone rubber composition, thereby obtaining an endless belt with a cured elastic layer 1d. The brightness of the elastic layer 1d at this time was 15.

[0115] Next, an addition-curing silicone rubber adhesive (product name: SE1819CV A / B; manufactured by Toray Dow Corning Co., Ltd.) was applied almost uniformly to the surface of the elastic layer 1d of the cured endless belt as an adhesive layer 1e, to a thickness of approximately 10 μm. Then, a fluororesin tube F, which had been extruded from PFA (product name: AP-231SH; manufactured by Daikin Industries, Ltd.) to an inner diameter of 23 mm and a thickness of 20 μm, and whose inner surface had been etched, was laminated onto it while expanding its diameter as a release layer 1f. The visible light transmittance of the PFA tube used at this time was 60%.

[0116] Subsequently, by uniformly rubbing the belt surface over the fluororesin tube F, excess adhesive was scraped out from between the elastic layer 1d and the fluororesin tube F until it was thinned to about 5 μm. The adhesive was cured by heating this endless belt in an electric furnace set to 200°C for one hour, thereby fixing the fluororesin tube onto the elastic layer 1d.

[0117] The resulting endless belt was inserted into a heating cylinder with an inner diameter of φ42 mm and heat-treated using a band heater inside the heating cylinder. The heating control temperature at the end of this fixing member was set to 330°C, and the heating was controlled so that the actual temperature of the release layer 1f was above the melting temperature of PFA. The heating time was set to 3 minutes after the fixing film was placed in the heating cylinder, which is the time required for the actual temperature of the release layer 1f to reach the desired temperature.

[0118] After 3 minutes of being placed in the chamber, the heating chamber was cooled to 200°C at a rate of 20°C / min, and then removed from the heating chamber and placed in a room temperature atmosphere to obtain an endless belt with increased crystallinity of the release layer 1f. Subsequently, the endless belt was marked using a UV laser from KEYENCE's MD-U1000C. The irradiation conditions were a laser output of 90% and a working distance (WD) of 25 mm. The letter string (Lot: ABC) was marked at 1 mm x 2 mm per character, and the 2D barcode was marked at 3 mm x 3 mm.

[0119] Finally, the ends of the marked endless belt were cut to obtain a fixed belt with a width of 336.5 mm.

[0120] (3) Evaluation of markings We confirmed that the two-dimensional barcode (3mm x 3mm) formed on the mark could be read using a barcode reader (Keyence BT-W250). The read rate was calculated from the number of times the barcode was read out of 20 scans. In addition, the visibility of the mark was ranked according to the following criteria. A: Can immediately identify the letters and numbers written on the page. B: The letters and numbers written are legible, but the resolution is poor, or the contrast is too small, making it difficult to see. C: The lines of letters and numbers are blurred, resulting in poor resolution, or the difference in shading is too small to be visually discernible.

[0121] Furthermore, the durability of the marked portion 1L was evaluated. Figure 7 is a schematic diagram illustrating the evaluation method for the durability of the marked portion 1L. A sample was prepared by cutting out and fixing the fixing belt 1 onto a 50mm x 50mm stainless steel plate 70, and its pressure resistance durability was evaluated. The evaluation conditions were a sample surface temperature of 240°C and a load F of 10N, and the pressure resistance durability test was performed by moving the pressure roller 71 (width 10mm, diameter 15mm) back and forth for 10 hours in the direction of the arrow in Figure 7. In the evaluation of pressure resistance durability, if the marked portion 1L did not disappear after the test, it was ranked as A, and if it had disappeared, it was ranked as C.

[0122] <Example 2> A fixing belt was obtained in the same manner as in Example 1, except that the laser output was changed to 60% during the marking process.

[0123] <Example 3> A fixing belt was obtained in the same manner as in Example 1, except that the thickness of the fluororesin tube was changed to 50 μm.

[0124] <Comparative Example 1> A fixing belt was obtained in the same manner as in Example 1, except that the laser output was changed to 20% during the marking process.

[0125] <Comparative Example 2> The marking process was carried out using an inkjet printer (Keyence MK-G inkjet printer) instead of a UV laser.

[0126] <Comparative Example 3> In the marking process, a fixing belt was obtained in the same manner as in Example 1, except that the UV laser was irradiated after the formation of the elastic layer, rather than after the formation of the release layer.

[0127] <Comparative Example 4> A fixing belt was obtained in the same manner as in Example 1, except that silica (Tospar, manufactured by Momentive) was added to the fluororesin tube and a fluororesin tube with low visible light transmittance was used.

[0128] <Comparative Example 5> A fixing belt was obtained in the same manner as in Example 1, except that 50 parts of magnesium oxide (StarMag, manufactured by Kamishima Chemical Co., Ltd.) was added to the elastic layer as a filler in addition to metallic silicon.

[0129] The results of these evaluations are summarized in Table 1 below. [Table 1]

[0130] As shown in Table 1, in Examples 1 to 3, the marked area 1L appeared brighter (high contrast) against its surroundings, resulting in good visibility. Furthermore, the durability of the marked area was confirmed to be excellent. In particular, Examples 1 and 3, where a portion of the bubble's peripheral surface was in contact with the surface layer, showed good visibility and a high success rate for barcode reading.

[0131] On the other hand, in Comparative Examples 1 to 5, the marked area 1L was not brightly visible compared to its surroundings (low contrast), resulting in poor visibility. Furthermore, in Comparative Example 2, the marked area also disappeared quickly due to friction.

[0132] The embodiment shown in this example provides a laminated member with good visibility of the marked portion 1L, and a method for manufacturing the same.

[0133] The disclosure of embodiments of the present invention includes the following configurations. (Composition 1) A laminated member in which a base layer, an adhesive layer, and a surface layer are laminated in this order, The underlying layer has a lightness of 15 or less. The surface layer has a visible light transmittance of 60% or more. A laminated member characterized in that air bubbles exist between the surface layer and the underlayer, and these air bubbles form a mark that is visible from the surface of the laminated member. (Configuration 2) The laminated member according to configuration 1, characterized in that a portion of the circumferential surface of the air bubble is in contact with the surface layer. (Method 1) A method for manufacturing a laminated member having a mark portion visible from the surface, A method for manufacturing a laminated member, characterized in that a pre-treatment laminated member, in which a base layer with a brightness of 15 or less, an adhesive layer, and a surface layer with a visible light transmittance of 60% or more are laminated in this order, is irradiated with laser light from the surface layer side to create bubbles between the base layer and the surface layer, thereby forming the marked portion. (Composition 3) A cylindrical electrophotographic component comprising a laminated structure in which an elastic layer, an adhesive layer, and a surface layer are laminated in this order, The elastic layer has a brightness of 15 or less. The surface layer has a visible light transmittance of 60% or more. An electrophotographic component characterized in that air bubbles exist between the surface layer and the elastic layer, and these bubbles form a mark that is visible from the surface of the laminated structure. (Composition 4) The electrophotographic component according to configuration 3, characterized in that a portion of the circumferential surface of the bubble is in contact with the surface layer. [Explanation of symbols]

[0134] 1. Fixing belt (electrophotographic component) 14. Nip section t toner image P recording material 1a Inner sliding layer 1b Cylindrical substrate 1c Primer layer 1d rubber layer 1e adhesive layer 1f Fluorine-based resin layer 1L Mark 100 Fixing device K Extended Type

Claims

1. A laminated member in which a base layer, an adhesive layer, and a surface layer are laminated in this order, The underlying layer has a lightness of 15 or less. The surface layer has a visible light transmittance of 60% or more. A laminated member characterized in that air bubbles exist between the surface layer and the underlayer, and these air bubbles form a mark that is visible from the surface of the laminated member.

2. The laminated member according to claim 1, characterized in that a portion of the circumferential surface of the air bubble is in contact with the surface layer.

3. A method for manufacturing a laminated member having a mark portion visible from the surface, A method for manufacturing a laminated member, characterized in that a pre-treatment laminated member, in which a base layer with a brightness of 15 or less, an adhesive layer, and a surface layer with a visible light transmittance of 60% or more are laminated in this order, is irradiated with laser light from the surface layer side to create bubbles between the base layer and the surface layer, thereby forming the marked portion.

4. A cylindrical electrophotographic component comprising a laminated structure in which an elastic layer, an adhesive layer, and a surface layer are laminated in this order, The elastic layer has a brightness of 15 or less. The surface layer has a visible light transmittance of 60% or more. An electrophotographic component characterized in that air bubbles exist between the surface layer and the elastic layer, and these bubbles form a mark that is visible from the surface of the laminated structure.

5. The electrophotographic member according to claim 4, characterized in that a portion of the circumferential surface of the bubble is in contact with the surface layer.

Images