A bushed charging roller

Abstract

The application discloses a sleeve type charging roller, which comprises, from inside to outside, a metal core, a buffer conductive layer, an elastic conductive layer, a protective sleeve layer and a surface conductive coating layer; each layer adopts a sleeve type nesting structure, and adjacent two layers are fixedly connected through a conductive adhesive; the sleeve type charging roller adopts a double protection structure of the protective sleeve layer and the surface conductive coating layer; the protective sleeve layer is made of a three-element ethylene-propylene rubber material which is resistant to cracking and wear; the surface conductive coating layer is made of a solidified conductive water-soluble polyurethane coating; and the elastic conductive layer is added with an anti-cracking agent; thus, the technical defect that the surface of the existing charging roller is prone to cracking is effectively solved; even under long-term use, external force collision or high-temperature environment, the charging roller is not prone to cracking, damage and falling-off, and the service life of the charging roller is prolonged.

Description

Technical Field

[0001] This invention relates to the field of accessories for electrostatic latent imaging equipment, specifically a sleeve-type charging roller. Background Technology

[0002] In electrostatic photography, the charging roller is one of the core components of electrostatic latent imaging devices such as laser printers, fax machines, and copiers. Its main function is to rotate in contact with the photosensitive drum, applying a mixed AC and DC voltage to charge the surface of the drum with a uniform charge, forming an electrostatic latent image. This image then works with toner, magnetic rollers, and other components to complete the printing process. The performance of the charging roller directly determines the image quality, equipment lifespan, and operational stability. Therefore, strict requirements are placed on the uniformity of its surface charge, wear resistance, crack resistance, and contact compatibility with the photosensitive drum.

[0003] In existing technologies, sleeve-type charging rollers typically consist of a metal core, a foam conductive elastic layer, and a surface-coated protective layer. This structure has significant technical drawbacks: Firstly, the surface-coated protective layer is fragile and prone to cracking during production, transportation, installation, and use due to external impacts, compression, or thermal expansion and contraction. Once cracked, it leads to uneven charge distribution on the surface of the charging roller, resulting in defects such as gray-white stripes and black spots in the printed image. In severe cases, it can render the charging roller unusable. Furthermore, the cracked protective layer can wear down the surface of the photosensitive drum, shortening its lifespan. Secondly, the connection stability between the layers of existing charging rollers is insufficient, leading to delamination and detachment after long-term use. Moreover, the elasticity of the elastic layer is poor, resulting in insufficient contact and adhesion with the photosensitive drum, causing uneven charging and affecting image quality. Summary of the Invention

[0004] The purpose of this invention is to provide a sleeve-type charging roller to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a sleeve-type charging roller, comprising, from the inside out, a metal core, a buffer conductive layer, an elastic conductive layer, a protective sleeve layer, and a surface conductive coating, wherein each layer adopts a sleeve-type nested structure, and adjacent layers are fixedly connected by conductive adhesive.

[0006] The metal core is made of stainless steel, with an outer diameter of 8-12mm and a length of 200-400mm. The surface is polished and plated with a conductive nickel layer with a thickness of 0.1-0.3mm.

[0007] The buffer conductive layer is made of conductive sponge material with a thickness of 1-3 mm, a foaming ratio of 1.5-3 times, and a foaming density of 0.3-0.6 g / cm³. It is uniformly mixed with conductive carbon black, and the amount of conductive carbon black added is 5-10% of the total mass of the buffer conductive layer.

[0008] The elastic conductive layer is made of silicone rubber with a thickness of 2-4 mm and a Shore hardness of 30-50 A. It contains a graphite conductive agent, and the amount of graphite conductive agent added is 8-15% of the total mass of the elastic conductive layer.

[0009] The protective sleeve layer is made of EPDM rubber with a thickness of 0.5-1.5mm and a surface treated with frosting, with a roughness Ra of 0.8-1.2μm.

[0010] The surface conductive coating is a conductive water-soluble polyurethane coating layer with a thickness of 30-40μm. It is made by mixing polyether polyurethane water-soluble resin, conductive agent, coupling agent and curing agent. The conductive agent is a mixture of tin oxide and antimony oxide, the coupling agent is a trifunctional coupling agent and the curing agent is a melamine-formaldehyde solution.

[0011] Preferably, the conductive adhesives used in this invention, between the buffer conductive layer and the metal core, between the buffer conductive layer and the elastic conductive layer, and between the elastic conductive layer and the protective sleeve layer, are all conductive silicone adhesives. The adhesive layer thickness is 0.05-0.1 mm, and the volume resistivity of the conductive adhesive is ≤10. 6 Ω·cm.

[0012] As a preferred embodiment of the present invention, the elastic conductive layer further includes an anti-aging agent and an anti-cracking agent. The anti-aging agent is 2-thiol benzothiazole, and the amount added is 0.5-1% of the total mass of the elastic conductive layer. The anti-cracking agent is polyethylene glycol, and the amount added is 1-2% of the total mass of the elastic conductive layer.

[0013] As a preferred embodiment of the present invention, the preparation process of the surface conductive coating is as follows: a water-soluble polyether polyurethane resin, a conductive agent, a coupling agent and a curing agent are mixed in a mass ratio of 100:15-20:3-5:8-12, filtered by ball milling, and then uniformly sprayed onto the surface of the protective sleeve layer by electrostatic spraying. The mixture is then heat-cured at 135-140℃ for 1.5-3 hours to form a surface conductive coating.

[0014] As a preferred embodiment of the present invention, both ends of the metal core are provided with positioning steps, the outer diameter of the positioning steps is 1-2 mm smaller than that of the metal core body, and the positioning steps are provided with annular grooves for assembling and fixing the bearing components of the charging roller.

[0015] As a preferred embodiment of the present invention, the inner wall of the protective sleeve layer is provided with uniformly distributed raised stripes, the height of the raised stripes is 0.1-0.2mm, the width is 0.3-0.5mm, and the spacing between adjacent raised stripes is 2-3mm, which is used to enhance the connection stability between the protective sleeve layer and the elastic conductive layer.

[0016] A method for preparing a sleeve-type charging roller, characterized by comprising the following steps:

[0017] A. Metal core pretreatment: Select a stainless steel round bar, cut and polish it, and then electroplat it with a conductive nickel layer. Then, make positioning steps and annular grooves at both ends to obtain the pretreated metal core.

[0018] B. Preparation and assembly of the buffer conductive layer: The conductive sponge raw material is mixed evenly with conductive carbon black and foaming agent, and then the buffer conductive sleeve is made by mixing, extrusion molding, vulcanization and foaming. The buffer conductive sleeve is then put on the surface of the metal core by conductive silicone adhesive, and after compaction, it is left to stand and cure for 1-2 hours.

[0019] C. Preparation and assembly of elastic conductive layer: Silicone rubber, graphite conductive agent, anti-aging agent, anti-cracking agent and vulcanizing agent are mixed evenly, and then mixed and extruded to form an elastic conductive sleeve. The sleeve is then applied to the surface of the buffer conductive layer with conductive silicone adhesive, and after compaction, it is subjected to heat stabilization treatment at 165-185℃ for 3-4 hours.

[0020] D. Assembly of protective sleeve layer: The EPDM rubber raw material is mixed, extruded and molded to form a protective sleeve. The inner wall is processed with raised stripes. The protective sleeve is put on the surface of the elastic conductive layer by conductive silicone adhesive. After compaction, it is left to cure for 1-2 hours. Then it is ground to the preset outer diameter on a grinding machine.

[0021] E. Preparation of conductive coating: Mix polyether polyurethane water-soluble resin, conductive agent, coupling agent and curing agent in proportion, filter by ball milling, and then spray it on the surface of the protective sleeve layer by electrostatic spraying, and then heat cure at 135-140℃ for 1.5-3 hours.

[0022] F. Finished product processing: The assembled charging roller is cut to the preset length on a lathe. After passing the inspection, the finished sleeve-type charging roller is obtained.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This sleeve-type charging roller adopts a double protection structure of a protective sleeve layer and a surface conductive coating. The protective sleeve layer is made of EPDM rubber, which is crack-resistant and wear-resistant. The surface conductive coating is made of cured conductive water-soluble polyurethane coating. Combined with the anti-cracking agent added to the elastic conductive layer, it effectively solves the technical defect of easy cracking on the surface of existing charging rollers. Even in long-term use, external impact or high temperature environment, it is not easy to crack, break or fall off, thus extending the service life of the charging roller.

[0025] This sleeve-type charging roller has a three-layer conductive structure consisting of a buffer conductive layer, an elastic conductive layer, and a surface conductive coating. Each layer contains a suitable conductive agent, and adjacent layers are connected by a conductive adhesive to ensure smooth and uniform charge conduction. This allows the photosensitive drum surface to be charged evenly, avoiding imaging defects caused by uneven charging and improving printing and copying quality. Attached Figure Description

[0026] Figure 1 This is an external schematic diagram of a sleeve-type charging roller according to the present invention;

[0027] Figure 2 This is a schematic diagram of the structural composition of a sleeve-type charging roller according to the present invention.

[0028] In the diagram: 1. Metal core; 2. Buffer conductive layer; 3. Elastic conductive layer; 4. Protective sleeve layer; 5. Conductive coating; 6. Conductive adhesive; 7. Positioning step; 8. Annular groove; 9. Raised stripes. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0030] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] Please see Figure 1-2 One embodiment provided by the present invention:

[0033] Example 1

[0034] A sleeve-type charging roller comprises, from the inside out, a metal core 1, a buffer conductive layer 2, an elastic conductive layer 3, a protective sleeve layer 4, and a surface conductive coating 5. Each layer adopts a sleeve-type nested structure, and adjacent layers are fixedly connected by a conductive adhesive 6 to ensure smooth charge conduction, while improving the connection stability between layers and preventing delamination and detachment.

[0035] The metal core 1 is made of stainless steel, which has excellent conductivity, rigidity, and corrosion resistance, making it suitable as the core carrier for charge conduction and supporting the entire charging roller structure. The outer diameter of the metal core 1 is set at 8-12mm, and the length is 200-400mm, adaptable to different models of electrostatic latent imaging equipment. The surface is polished to remove burrs and impurities, and then plated with a 0.1-0.3mm thick conductive nickel layer to further improve conductivity and corrosion resistance, preventing oxidation of the metal core 1 from affecting its conductivity. Furthermore, positioning steps 7 are provided at both ends of the metal core 1. The outer diameter of the positioning steps 7 is 1-2mm smaller than the main body of the metal core 1, and annular grooves 8 are provided on the positioning steps 7 for assembling and fixing the bearing components of the charging roller, ensuring stable rotation of the charging roller within the equipment.

[0036] A buffer conductive layer 2 is disposed on the outside of the metal core 1. It is made of conductive sponge with a thickness of 1-3 mm, a foaming ratio of 1.5-3 times, and a foaming density of 0.3-0.6 g / cm³. Conductive carbon black is uniformly mixed within the layer, with the amount of conductive carbon black added being 5-10% of the total mass of the buffer conductive layer 2. The main function of the buffer conductive layer 2 is to buffer the contact pressure between the charging roller and the photosensitive drum, preventing excessive pressure from damaging the photosensitive drum. Simultaneously, it facilitates initial charge conduction, ensuring uniform charge distribution. The elastic properties of the conductive sponge allow the charging roller to better conform to the surface of the photosensitive drum, improving contact compatibility, while the addition of conductive carbon black ensures the conductivity of the buffer conductive layer 2, preventing charge conduction bottlenecks.

[0037] The elastic conductive layer 3 is disposed outside the buffer conductive layer 2, made of silicone rubber with a thickness of 2-4 mm and a Shore hardness of 30-50A. It contains a graphite conductive agent, with the amount of graphite conductive agent added being 8-15% of the total mass of the elastic conductive layer 3. Silicone rubber possesses good elasticity, resistance to high and low temperatures, and anti-aging properties, enabling it to adapt to the high-temperature working environment inside the equipment. Its Shore hardness of 30-50A ensures good contact with the photosensitive drum while preventing wear caused by excessive compression. The graphite conductive agent has excellent conductivity and stability, further optimizing charge conduction and ensuring uniform charge distribution on the charging roller surface. In addition, the elastic conductive layer 3 also contains an anti-aging agent and an anti-cracking agent. The anti-aging agent is 2-thiol-benzothiazole, added at 0.5-1% of the total mass of the elastic conductive layer 3, which slows down the aging rate of the elastic conductive layer 3. The anti-cracking agent is polyethylene glycol, added at 1-2% of the total mass of the elastic conductive layer 3, which effectively prevents cracking of the elastic conductive layer 3 during long-term use.

[0038] The protective sleeve layer 4 is located outside the elastic conductive layer 3. It is made of EPDM rubber with a thickness of 0.5-1.5 mm and a frosted surface with a roughness Ra of 0.8-1.2 μm. EPDM rubber has good wear resistance, aging resistance, and crack resistance, effectively protecting the internal elastic conductive layer 3 and buffer conductive layer 2 from damage caused by external force wear and environmental factors. The frosted surface treatment increases the friction between the protective sleeve layer 4 and the photosensitive drum, ensuring synchronous rotation of both and preventing toner adsorption on the charging roller surface, thus improving image quality. In addition, the inner wall of the protective sleeve layer 4 has uniformly distributed raised stripes 9. The height of the raised stripes 9 is 0.1-0.2 mm, the width is 0.3-0.5 mm, and the spacing between adjacent raised stripes 9 is 2-3 mm. This enhances the connection stability between the protective sleeve layer 4 and the elastic conductive layer 3, preventing relative slippage between them.

[0039] A conductive coating 5 is applied to the outside of the protective sleeve layer 4. It is a conductive water-soluble polyurethane coating layer with a thickness of 30-40 μm, composed of a polyether polyurethane water-soluble resin, a conductive agent, a coupling agent, and a curing agent. The conductive agent is a mixture of tin oxide and antimony oxide in a 3:1 ratio, which improves the conductivity uniformity and stability of the conductive coating 5. The coupling agent is a trifunctional coupling agent, which enhances the adhesion between the conductive coating 5 and the protective sleeve layer 4, preventing coating peeling. The curing agent is a melamine-formaldehyde solution, which improves the hardness and wear resistance of the coating. The preparation process of the conductive coating 5 is as follows: the polyether polyurethane water-soluble resin, conductive agent, coupling agent, and curing agent are mixed in a mass ratio of 100:15-20:3-5:8-12, filtered through ball milling, and then uniformly sprayed onto the surface of the protective sleeve layer 4 using electrostatic spraying. Finally, it is heat-cured at 135-140℃ for 1.5-3 hours to form the conductive coating 5. This coating not only further optimizes charge uniformity but also enhances the wear resistance and crack resistance of the charging roller, extending its service life.

[0040] To ensure the stability of the connection and the continuity of conductivity between the layers, the conductive adhesive 6 between adjacent layers is a conductive silicone adhesive with a thickness of 0.05-0.1 mm and a volume resistivity of ≤10 Ω·cm. 6 Ω·cm ensures a strong connection between layers while avoiding interference with charge conduction.

[0041] The present invention also provides a method for preparing the above-mentioned sleeve-type charging roller, specifically including the following steps:

[0042] A. Pre-treatment of metal core 1: Select a stainless steel round bar, cut it according to the preset size, and then polish its surface with polishing equipment to remove surface burrs and impurities to ensure a smooth surface; then use electroplating process to plate a conductive nickel layer on its surface, with the nickel layer thickness controlled at 0.1-0.3mm; finally, process positioning steps 7 and annular grooves 8 at both ends of metal core 1. The outer diameter of positioning steps 7 is 1-2mm smaller than the main body of metal core 1, and the annular grooves 8 are used to assemble bearing components, thus obtaining the pre-treated metal core 1.

[0043] B. Preparation and assembly of the buffer conductive layer 2: The conductive sponge raw material, conductive carbon black, foaming agent and crosslinking agent are mixed evenly and kneaded in a mixer for 1-2 hours. Then, the mixture is extruded and shaped through an extruder to obtain an uncured conductive sponge sleeve. The uncured conductive sponge sleeve is placed in a microwave bath at a temperature of 170-210℃ for vulcanization and foaming to form a buffer conductive sleeve. Then, conductive silicone adhesive is evenly applied to the surface of the metal core 1. The buffer conductive sleeve is then placed on the surface of the metal core 1, pressed with a special clamp, and allowed to stand and cure for 1-2 hours to ensure a firm connection between the buffer conductive layer 2 and the metal core 1.

[0044] C. Preparation and assembly of elastic conductive layer 3: Silicone rubber, graphite conductive agent, anti-aging agent, anti-cracking agent and vulcanizing agent are mixed evenly and kneaded in a mixer for 1.5-2.5 hours. Then, the mixture is extruded and shaped to form an elastic conductive sleeve. Conductive silicone adhesive is evenly applied to the surface of the buffer conductive layer 2. The elastic conductive sleeve is then placed on the surface of the buffer conductive layer 2 and compacted with a special clamp. The sleeve is then placed in a constant temperature oven and subjected to heat stabilization treatment at 165-185℃ for 3-4 hours to ensure a firm connection between the elastic conductive layer 3 and the buffer conductive layer 2, while also improving the stability of the elastic conductive layer 3.

[0045] D. Assembly of Protective Sleeve Layer 4: Mix EPDM rubber raw materials, vulcanizing agent and accelerator evenly, mix in a mixer for 1-2 hours, and then extrude and shape through an extruder to form a protective sleeve. Process raised stripes 9 on the inner wall of the protective sleeve. The height of the raised stripes 9 is 0.1-0.2mm, the width is 0.3-0.5mm, and the spacing between adjacent raised stripes 9 is 2-3mm. Apply conductive silicone adhesive evenly to the surface of the elastic conductive layer 3, put the protective sleeve on the surface of the elastic conductive layer 3, press it with a special fixture, let it stand and cure for 1-2 hours, and then grind it to the preset outer diameter on a grinding machine to ensure that the surface of the protective sleeve layer 4 is smooth and the dimensions are accurate.

[0046] E. Preparation of surface conductive coating 5: Polyether polyurethane water-soluble resin, conductive agent (mixture of tin oxide and antimony oxide), coupling agent and curing agent are mixed in a mass ratio of 100:15-20:3-5:8-12 and ball-milled in a ball mill for 2-3 hours. Then, impurities are removed by filtration to obtain a conductive water-soluble coating. The conductive water-soluble coating is uniformly sprayed onto the surface of the protective sleeve layer 4 using electrostatic spraying, with the spraying thickness controlled at 30-40μm. Then, the sprayed charging roller is placed in a constant temperature oven and heat-cured at 135-140℃ for 1.5-3 hours to form the surface conductive coating 5.

[0047] F. Finished product processing: Place the assembled charging roller into a lathe and cut it according to the preset length to remove the excess part; then clean and inspect the surface of the charging roller. The inspection items include surface flatness, conductivity, dimensional accuracy, etc. After passing the inspection, package and store it to obtain the finished sleeve-type charging roller.

[0048] Example 2

[0049] A sleeve-type charging roller comprises, from the inside out, a metal core 1, a buffer conductive layer 2, an elastic conductive layer 3, a protective sleeve layer 4, and a surface conductive coating 5. Each layer adopts a sleeve-type nested structure, and adjacent layers are fixedly connected by conductive silicone adhesive.

[0050] Metal core 1: Made of stainless steel, with an outer diameter of 10mm and a length of 300mm. The surface is polished and plated with a 0.2mm thick conductive nickel layer. Positioning steps 7 are provided at both ends. The outer diameter of positioning steps 7 is 8mm. Annular grooves 8 are provided on positioning steps 7.

[0051] Buffer conductive layer 2: made of conductive sponge material, 2mm thick, with a foaming ratio of 2 times and a foaming density of 0.45g / cm³, and mixed with 7% (mass fraction) conductive carbon black.

[0052] Elastic conductive layer 3: made of silicone rubber, 3mm thick, with a Shore hardness of 40A, containing 12% (mass fraction) graphite conductive agent, 0.8% (mass fraction) 2-thiol benzothiazole (anti-aging agent), and 1.5% (mass fraction) polyethylene glycol (anti-cracking agent).

[0053] Protective sleeve layer 4: made of EPDM rubber, with a thickness of 1mm, and the surface is sanded with a roughness Ra of 1.0μm. The inner wall is provided with raised stripes 9, the height of the raised stripes 9 is 0.15mm, the width is 0.4mm, and the spacing between adjacent raised stripes 9 is 2.5mm.

[0054] Surface conductive coating 5: Conductive water-soluble polyurethane coating layer with a thickness of 35μm, which is made by mixing polyether polyurethane water-soluble resin, conductive agent (tin oxide to antimony oxide mass ratio 3:1), trifunctional coupling agent and melamine-formaldehyde solution in a mass ratio of 100:18:4:10.

[0055] Conductive silicone adhesive: The adhesive layer thickness is 0.08 mm, and the volume resistivity is 5 × 10⁻⁶. 5 Ω·cm.

[0056] The above-mentioned method for preparing the sleeve-type charging roller includes the following steps:

[0057] A. Pretreatment of metal core 1: Select a stainless steel round bar, cut it into a blank with a length of 300mm, polish it, and then electroplate a 0.2mm thick conductive nickel layer. Then, process positioning steps 7 and annular grooves 8 at both ends to obtain the pretreated metal core 1.

[0058] B. Preparation and assembly of the buffer conductive layer 2: The conductive sponge raw material, 7% conductive carbon black, foaming agent and crosslinking agent are mixed evenly and kneaded for 1.5 hours. After extrusion molding, it is placed in a microwave bath at 190℃ for vulcanization and foaming to make a buffer conductive sleeve. The conductive silicone adhesive is applied to the surface of the metal core 1, and the buffer conductive sleeve is placed on the surface of the metal core 1. After compaction, it is left to stand and cure for 1.5 hours.

[0059] C. Preparation and assembly of elastic conductive layer 3: Silicone rubber, 12% graphite conductive agent, 0.8% 2-thiol benzothiazole, 1.5% polyethylene glycol and vulcanizing agent are mixed evenly and kneaded for 2 hours. The mixture is then extruded and molded into an elastic conductive sleeve. Conductive silicone adhesive is applied to the surface of the buffer conductive layer 2, and the elastic conductive sleeve is placed on it. After compaction, it is heat-stabilized at 175°C for 3.5 hours.

[0060] D. Assembly of protective sleeve layer 4: Mix EPDM rubber raw materials, vulcanizing agent and accelerator evenly, knead for 1.5 hours, extrude and shape into protective sleeve, process raised stripes 9 on the inner wall; apply conductive silicone adhesive to the surface of elastic conductive layer 3, put the protective sleeve on it, press it and let it stand to cure for 1.5 hours, and then grind it to the preset outer diameter on a grinding machine.

[0061] E. Preparation of surface conductive coating 5: Mix polyether polyurethane water-soluble resin, conductive agent, coupling agent and curing agent in a mass ratio of 100:18:4:10, ball mill for 2.5 hours, filter and then spray on the surface of the protective sleeve layer 4 by electrostatic spraying with a coating thickness of 35μm, and then heat cure at 138℃ for 2 hours.

[0062] F. Finished product processing: The assembled charging roller is cut to 300mm on a lathe, cleaned and inspected. The surface flatness, conductivity and dimensional accuracy are all qualified, and the finished product is obtained.

[0063] Example 3

[0064] A sleeve-type charging roller comprises, from the inside out, a metal core 1, a buffer conductive layer 2, an elastic conductive layer 3, a protective sleeve layer 4, and a surface conductive coating 5. Each layer adopts a sleeve-type nested structure, and adjacent layers are fixedly connected by conductive silicone adhesive.

[0065] Metal core 1: Made of stainless steel, with an outer diameter of 8mm and a length of 200mm. The surface is polished and plated with a 0.1mm thick conductive nickel layer. It has positioning steps 7 at both ends, with an outer diameter of 7mm and an annular groove 8 on the positioning steps 7.

[0066] Buffer conductive layer 2: made of conductive sponge material, 1mm thick, with a foaming ratio of 1.5 times and a foaming density of 0.3g / cm³, and mixed with 5% (mass fraction) conductive carbon black.

[0067] Elastic conductive layer 3: made of silicone rubber, 2mm thick, with a Shore hardness of 30A, containing 8% (mass fraction) graphite conductive agent, 0.5% (mass fraction) 2-thiol benzothiazole (anti-aging agent), and 1% (mass fraction) polyethylene glycol (anti-cracking agent).

[0068] Protective sleeve layer 4: made of EPDM rubber, with a thickness of 0.5mm, and the surface is sanded with a roughness Ra of 0.8μm. The inner wall is provided with raised stripes 9, with a height of 0.1mm, a width of 0.3mm, and a spacing of 2mm between adjacent raised stripes 9.

[0069] Surface conductive coating 5: Conductive water-soluble polyurethane coating layer with a thickness of 30μm, which is made by mixing polyether polyurethane water-soluble resin, conductive agent (tin oxide to antimony oxide mass ratio 3:1), trifunctional coupling agent and melamine-formaldehyde solution in a mass ratio of 100:15:3:8.

[0070] Conductive silicone adhesive: adhesive layer thickness is 0.05mm, volume resistivity is 3×10⁻⁶. 5 Ω·cm.

[0071] The preparation method is basically the same as in Example 1, except that the process parameters of each step are adjusted: the microwave bath temperature is 170°C, the thermal stabilization treatment temperature is 165°C and the time is 3 hours, and the surface conductive coating 5 is heat-cured at 135°C and for 1.5 hours.

[0072] Example 4

[0073] A sleeve-type charging roller comprises, from the inside out, a metal core 1, a buffer conductive layer 2, an elastic conductive layer 3, a protective sleeve layer 4, and a surface conductive coating 5. Each layer adopts a sleeve-type nested structure, and adjacent layers are fixedly connected by conductive silicone adhesive.

[0074] Metal core 1: Made of stainless steel, with an outer diameter of 12mm and a length of 400mm. The surface is polished and plated with a 0.3mm thick conductive nickel layer. Positioning steps 7 are provided at both ends. The outer diameter of positioning steps 7 is 10mm. Annular grooves 8 are provided on positioning steps 7.

[0075] Buffer conductive layer 2: made of conductive sponge material, 3mm thick, with a foaming ratio of 3 times and a foaming density of 0.6g / cm³, and mixed with 10% (mass fraction) of conductive carbon black.

[0076] Elastic conductive layer 3: made of silicone rubber, 4mm thick, with a Shore hardness of 50A, containing 15% (mass fraction) graphite conductive agent, 1% (mass fraction) 2-thiol benzothiazole (anti-aging agent), and 2% (mass fraction) polyethylene glycol (anti-cracking agent).

[0077] Protective sleeve layer 4: made of EPDM rubber, with a thickness of 1.5mm, and the surface is sanded with a roughness Ra of 1.2μm. The inner wall is provided with raised stripes 9, with a height of 0.2mm, a width of 0.5mm, and a spacing of 3mm between adjacent raised stripes 9.

[0078] Surface conductive coating 5: Conductive water-soluble polyurethane coating layer with a thickness of 40μm, which is made by mixing polyether polyurethane water-soluble resin, conductive agent (tin oxide to antimony oxide mass ratio 3:1), trifunctional coupling agent and melamine-formaldehyde solution in a mass ratio of 100:20:5:12.

[0079] Conductive silicone adhesive: The adhesive layer thickness is 0.1 mm, and the volume resistivity is 8 × 10⁻⁶. 5 Ω·cm.

[0080] The preparation method is basically the same as in Example 1, except that the process parameters of each step are adjusted: the microwave bath temperature is 210℃, the heat stabilization treatment temperature is 185℃ and the time is 4 hours, and the surface conductive coating 5 is heat cured at 140℃ and for 3 hours.

[0081] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A sleeve-type charging roller, characterized in that, From the inside out, it includes a metal core (1), a buffer conductive layer (2), an elastic conductive layer (3), a protective sleeve layer (4), and a surface conductive coating (5). Each layer adopts a sleeve-type nested structure, and adjacent layers are fixedly connected by conductive adhesive (6). The metal core (1) is made of stainless steel, with an outer diameter of 8-12mm and a length of 200-400mm. The surface is polished and plated with a conductive nickel layer with a thickness of 0.1-0.3mm. The buffer conductive layer (2) is made of conductive sponge material with a thickness of 1-3 mm, a foaming ratio of 1.5-3 times, and a foaming density of 0.3-0.6 g / cm³. It is uniformly mixed with conductive carbon black, and the amount of conductive carbon black added is 5-10% of the total mass of the buffer conductive layer (2). The elastic conductive layer (3) is made of silicone rubber with a thickness of 2-4 mm and a Shore hardness of 30-50 A. It contains graphite conductive agent, and the amount of graphite conductive agent added is 8-15% of the total mass of the elastic conductive layer (3). The protective sleeve layer (4) is made of EPDM rubber with a thickness of 0.5-1.5mm and a surface treated with sandblasting, with a roughness Ra of 0.8-1.2μm; The surface conductive coating (5) is a conductive water-soluble polyurethane coating layer with a thickness of 30-40μm. It is made by mixing polyether polyurethane water-soluble resin, conductive agent, coupling agent and curing agent. The conductive agent is a mixture of tin oxide and antimony oxide, the coupling agent is a trifunctional coupling agent and the curing agent is melamine-formaldehyde solution.

2. The sleeve-type charging roller according to claim 1, characterized in that, The conductive adhesives (6) between the buffer conductive layer (2) and the metal core (1), between the buffer conductive layer (2) and the elastic conductive layer (3), and between the elastic conductive layer (3) and the protective sleeve layer (4) are all conductive silicone adhesives. The thickness of the adhesive layer is 0.05-0.1 mm, and the volume resistivity of the conductive adhesive (6) is ≤10. 6 Ω·cm.

3. The sleeve-type charging roller according to claim 1, characterized in that, The elastic conductive layer (3) also contains an anti-aging agent and an anti-cracking agent. The anti-aging agent is 2-thiol benzothiazole, and the amount added is 0.5-1% of the total mass of the elastic conductive layer (3). The anti-cracking agent is polyethylene glycol, and the amount added is 1-2% of the total mass of the elastic conductive layer (3).

4. The sleeve-type charging roller according to claim 1, characterized in that, The preparation process of the surface conductive coating (5) is as follows: the polyether polyurethane water-soluble resin, conductive agent, coupling agent and curing agent are mixed in a mass ratio of 100:15-20:3-5:8-12, filtered by ball milling, and then uniformly sprayed on the surface of the protective sleeve layer (4) by electrostatic spraying. Then, it is heat-cured at 135-140℃ for 1.5-3 hours to form the surface conductive coating (5).

5. The sleeve-type charging roller according to claim 1, characterized in that, Both ends of the metal core (1) are provided with positioning steps (7). The outer diameter of the positioning steps (7) is 1-2 mm smaller than that of the main body of the metal core (1). The positioning steps (7) are provided with annular grooves (8) for assembling and fixing the bearing components of the charging roller.

6. The sleeve-type charging roller according to claim 1, characterized in that, The inner wall of the protective sleeve layer (4) is provided with uniformly distributed raised stripes (9). The height of the raised stripes (9) is 0.1-0.2 mm, the width is 0.3-0.5 mm, and the spacing between adjacent raised stripes (9) is 2-3 mm, which is used to enhance the connection stability between the protective sleeve layer (4) and the elastic conductive layer (3).

7. A method for preparing a sleeve-type charging roller as described in any one of claims 1-6, characterized in that, Includes the following steps: A. Metal core (1) pretreatment: Select a stainless steel round bar, cut and polish it, and then use electroplating process to plate a conductive nickel layer on its surface. Then, make positioning steps (7) and annular grooves (8) at both ends to obtain the pretreated metal core (1). B. Preparation and assembly of the buffer conductive layer (2): The conductive sponge raw material is mixed evenly with conductive carbon black and foaming agent, and then the buffer conductive sleeve is made by mixing, extrusion molding, vulcanization and foaming. The buffer conductive sleeve is then placed on the surface of the metal core (1) by conductive silicone adhesive, and then compacted and left to stand for 1-2 hours to cure. C. Preparation and assembly of elastic conductive layer (3): Silicone rubber, graphite conductive agent, anti-aging agent, anti-cracking agent and vulcanizing agent are mixed evenly, and then mixed and extruded to form an elastic conductive sleeve. The sleeve is then applied to the surface of the buffer conductive layer (2) with conductive silicone adhesive, and after compaction, it is subjected to heat stabilization treatment at 165-185℃ for 3-4 hours. D. Assembly of protective sleeve layer (4): The EPDM rubber raw material is mixed and extruded to form a protective sleeve. The inner wall is processed with raised stripes (9). The protective sleeve is placed on the surface of the elastic conductive layer (3) by conductive silicone adhesive. After compaction, it is left to stand and cure for 1-2 hours. Then it is ground on a grinding machine to the preset outer diameter. E. Preparation of surface conductive coating (5): Mix polyether polyurethane water-soluble resin, conductive agent, coupling agent and curing agent in proportion, filter by ball milling, and then spray it on the surface of the protective sleeve layer (4) by electrostatic spraying, and then heat cure at 135-140℃ for 1.5-3 hours. F. Finished product processing: The assembled charging roller is cut to the preset length on a lathe. After passing the inspection, the finished sleeve-type charging roller is obtained.

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