Conductive rubber roller and method for manufacturing a conductive rubber roller

Abstract

We offer a new type of rubber roller. [Solution] One aspect of the invention is a method for manufacturing a conductive rubber roller comprising a conductive metal shaft and a conductive rubber layer covering its outer surface, comprising: an adhesive coating step of applying a liquid adhesive to the outer surface of the metal shaft; a rubber cylinder fitting step of fitting a conductive rubber cylinder to the outside of the metal shaft after the liquid adhesive has dried; and a rubber processing step of polishing or cutting the rubber cylinder to a thickness of 0.2 to 0.3 mm to form the rubber layer, wherein in the adhesive coating step, the liquid adhesive is applied to the outer surface of the metal shaft such that concentrated areas of the liquid adhesive are dispersed and scattered.

Description

Technical Field

[0001] The present disclosure relates to a conductive rubber roller and a method for manufacturing the same.

Background Art

[0002] A rubber roller in which a metal shaft is covered with a rubber layer is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0046] , etc.)

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a novel rubber roller.

Means for Solving the Problems

[0005] One aspect of the invention is a method for manufacturing a conductive rubber roller including a conductive metal shaft and a conductive rubber layer covering an outer peripheral surface thereof, the method including: an adhesive application step of applying a liquid adhesive to the outer peripheral surface of the metal shaft; a rubber cylinder fitting step of fitting a conductive rubber cylinder outside the metal shaft after drying the liquid adhesive; and a rubber processing step of polishing or cutting the rubber cylinder until it has a thickness of 0.2 to 0.3 mm to form the rubber layer, wherein in the adhesive application step, the liquid adhesive is applied to the outer peripheral surface of the metal shaft such that concentrated locations of the liquid adhesive are dispersed and dot-like.

Brief Description of the Drawings

[0006] [Figure 1] FIG. 1 is a perspective view of a conductive rubber roller according to the first embodiment [Figure 2]Figure 2 is a magnified view of a portion of the metal shaft to which adhesive has been applied. [Figure 3] Figure 3 is a cross-sectional view of the adhesive between the metal shaft and the rubber layer of a conductive roller. [Figure 4] Figure 4 is a side view of a coating roller applying adhesive to a metal shaft. [Figure 5] Figure 5 is a cross-sectional view of a coating roller applying adhesive to a metal shaft. [Figure 6] Figure 6 is a magnified photograph of the surface of the coating roller. [Figure 7] Figure 7 is a cross-sectional view of adhesive applied to a metal shaft. [Figure 8] Figure 8 is a cross-sectional view of the rubber tube fitted to the outside of the metal shaft. [Figure 9] Figure 9 is a perspective view of a rubber tube with its outer surface shaved off. [Figure 10] Figure 10 is a conceptual diagram of a circuit for measuring electrical resistance. [Figure 11] Figure 11 is a table showing the evaluation results of conductive rubber rollers for the examples and comparative examples. [Modes for carrying out the invention]

[0007] [First Embodiment] Figure 1 shows a conductive rubber roller 10 (hereinafter simply referred to as "rubber roller 10") according to the first embodiment. The rubber roller 10 comprises a conductive metal shaft 11 and a conductive rubber layer 12 covering its outer surface. The rubber layer 12 is bonded and fixed to the metal shaft 11 by an adhesive 30.

[0008] Examples of the rubber roller 10 include rollers for office automation equipment. Examples of office automation equipment include printers, copiers, facsimile machines, and other image forming devices that employ an electrophotographic method. The rubber roller 10 may also be a roller (e.g., a drive roller) on which a belt (e.g., a transfer belt, intermediate transfer belt, or photoreceptor belt, etc.) of the office automation equipment is placed. In the example of this embodiment, the rubber roller 10 is a roller placed on the transfer belt of a tandem-type color image forming apparatus. Other examples of the rubber roller 10 for office automation equipment include toner supply rollers, charging rollers, transfer rollers, developing rollers, fixing rollers, paper feed rollers, paper discharge rollers, registration rollers, or cleaning rollers.

[0009] In this embodiment, the rubber layer 12 covers the shaft 11 except for both ends in the axial direction and is cylindrical in shape. In this embodiment, the thickness of the rubber layer 12 is 0.2 mm or more and 0.3 mm or less, and more preferably 0.25 mm or more and 0.3 mm or less. The JIS-A hardness of the rubber layer 12 is preferably 70 to 80. In this embodiment, the metal shaft 11 comprises small-diameter portions 11B which are exposed at both ends from the rubber layer 12, and large-diameter portions 11A which are covered by the rubber layer 12.

[0010] Examples of rubber materials for the rubber layer 12 include ethylene propylene diene rubber (EPDM), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), natural rubber (NR), butadiene rubber (BR), acrylic rubber (ACM), ethylene acrylate rubber (AEM), silicone or fluororubber (FKM), or materials containing at least some of these. In this embodiment, the rubber layer 12 is made of EPDM.

[0011] The rubber layer 12 contains a conductive material. In this embodiment, carbon is used as the conductive material, but it is not limited to this. The amount of conductive material can be appropriately set according to the required conductivity.

[0012] Examples of materials for the metal shaft 11 include aluminum, iron, steel, stainless steel, or brass, or alloys of these metals (for example, an alloy of aluminum and iron). In this embodiment, the metal shaft 11 is made of aluminum.

[0013] Examples of adhesive materials 30 include acrylic adhesives, silicone adhesives, urethane adhesives, and rubber adhesives. In this embodiment, the adhesive material 30 is an acrylic adhesive.

[0014] As shown in Figure 2, the adhesive 30 is applied to the outer surface of the metal shaft 11 such that concentrated areas S of the adhesive 30 are dispersed and scattered (in Figure 2, concentrated areas S are indicated by black circles). Concentrated areas S are areas on the coated surface of the adhesive 30 on the metal shaft 11 (the outer surface covered by the rubber layer 12) where the adhesive 30 is raised compared to other areas (see Figure 3). Concentrated areas S are provided in a bulging shape, such as a dome shape. Preferably, concentrated areas S are applied so that their diameter (size) is 50 μm or more and 300 μm or less. Note that the diameter (size) here refers to the distance between the two furthest points on the contour of the concentrated area S when viewed from the radially outside of the metal shaft 11 and the concentrated area S is not circular. The concentrated areas S may be arranged regularly or irregularly. Also, the shape and size of the concentrated areas S may be the same or different (they may be random).

[0015] The resistance value of the rubber roller 10 is preferably 6.0 logΩ or less, and more preferably 5.0 logΩ or less. Here, as the adhesive material 30, one with low conductivity is generally used. In this case, if the adhesive material 30 is evenly applied to the entire outer peripheral surface of the metal shaft 11, the conductivity between the metal shaft 11 and the rubber layer 12 may decrease, so the conductivity of the rubber roller 10 may decrease. On the other hand, in the rubber roller 10 of the present embodiment, the concentrated portions of the adhesive material 30 are dispersed and exist in spots on the metal shaft 11. That is, there are sparse portions on the outer peripheral surface of the metal shaft 11 where the adhesive material 30 does not concentrate. Therefore, it is possible to increase the conductivity of the rubber roller 10 compared to the case where the adhesive material 30 is evenly applied overall. Thereby, it becomes possible to make the resistance value of the rubber roller 10 6.0 logΩ or less. Note that on the outer peripheral surface of the metal shaft 11 (the outer peripheral surface of the large-diameter portion 11A), the portions other than the concentrated portion S may not be coated with the adhesive material 30, or may be thinly coated (for example, preferably half or less of the thickness of the concentrated portion S, more preferably one-third or less, and even more preferably one-fourth or less).

[0016] The rubber roller 10 of this embodiment is manufactured, for example, as follows. First, an adhesive coating process is performed in which a liquid adhesive 30 is applied to a metal shaft 11 (made of aluminum in this embodiment) using a roll coater (see Figure 4). In this embodiment, an acrylic adhesive diluted with a solvent is used as the adhesive 30. The roll coater is equipped with a coating roller 40, and the outer surface of the coating roller 40 to which the adhesive 30 is applied is pressed against the outer surface of the metal shaft 11 to coat the metal shaft 11 with the adhesive 30. In this embodiment, the outer surface of the coating roller 40 is made of a foam 41 (for example, a soft foam such as soft polyurethane foam). For example, when the adhesive 30 is applied, this foam 41 is pressed against the metal shaft 11 and makes contact in a concave state. This concave state of the coating roller 40 increases the contact area between the coating roller 40 and the metal shaft 11, making it possible to apply the adhesive 30 thoroughly. Furthermore, the application of the adhesive 30 (for example, application with foam) is not limited to being done with a roller, but may be done using methods other than a roller.

[0017] As shown in Figure 5, when the coating surface of the component (coating roller 40, etc.) that applies the adhesive 30 to the metal shaft 11 is made of foam 41, the liquid adhesive 30 enters the air bubbles 42 that open on the outer surface of the foam 41 (in Figure 5, the foam 41 is shown on the upper side). When the foam 41 is pressed against the metal shaft 11, the adhesive 30 containing the air bubbles 42 adheres to the outer surface of the metal shaft 11. This adhered adhesive 30 (for example, in a dome shape or other bulging shape) then becomes dispersed and scattered on the metal shaft 11 as concentrated areas S of adhesive 30 (see Figure 7).

[0018] The adhesive material 30 applied to the metal shaft 11 is dried. This drying is preferably performed by blowing air (air drying). The diameter (size) of the concentrated portion S of the adhesive material 30 after drying is preferably 50 μm or more and 300 μm or less. Also, the thickness of the concentrated portion S after drying (the thickness of the thickest portion at the concentrated portion S) is preferably 5 μm or more and 25 μm or less. When the thickness of the concentrated portion S is 5 μm or more, the adhesion between the metal shaft 11 and the rubber layer 12 is particularly good and preferable. When the thickness of the concentrated portion S is 25 μm or less, it is particularly preferable because it becomes easier to reduce the electrical resistance value.

[0019] The foam 41 used in the adhesive material application process preferably has a bubble 42 diameter of 50 μm or more and 200 μm or less. Also, for example, the foam 41 preferably has a number of bubbles (JIS K6400-1) of 125 to 500 bubbles / 25 mm. The foam 41 may have an open-cell structure, but preferably has a closed-cell structure. In the latter case, since the adhesive material 30 does not penetrate to the inside of the foam 41 and remains in the bubbles 42 opened on the outer surface of the foam 41, it becomes possible to easily form the scattered concentrated portions S. Note that the foam 41 may be manufactured by mold molding, or may be manufactured by the mechanical froth method by blowing an inert gas into the raw material and stirring. For example, in the latter case, the above-mentioned fine bubbles of 50 to 200 μm can be easily formed (see Fig. 6).

[0020] For example, the foam 41 includes polyurethane foam. In the example of this embodiment, it is a polyurethane foam manufactured by the mechanical froth method. It is not limited to this. For example, it may be a polyolefin foam (for example, polyethylene foam, polypropylene foam, etc.), or may be a melamine foam.

[0021] Next, as shown in Figure 8, a rubber cylinder fitting process is performed in which a conductive rubber cylinder 12A is fitted onto the outside of the metal shaft 11, onto which the adhesive 30 has dried. This process is carried out, for example, by blowing air into the inside of the rubber cylinder 12A to expand it. Once the rubber cylinder 12A is fitted onto the outside of the metal shaft 11, the rubber cylinder 12A and the metal shaft 11 are fixed together with the adhesive 30. In this embodiment, the rubber cylinder 12A is made of EPDM and contains carbon.

[0022] Next, as shown in Figure 9, a rubber processing step is performed in which the rubber cylinder 12A fitted to the outside of the metal shaft 11 is polished or cut to a thickness of 0.2 mm or more and 0.3 mm or less to form a rubber layer 12. In this embodiment, since the rubber cylinder 12A is fixed to the metal shaft 11 with adhesive 30, it is possible to suppress the rotation of the rubber cylinder 12A relative to the metal shaft 11 when the rubber cylinder 12A is cut to a thickness of 0.2 to 0.3 mm. Note that with rubber that is 0.2 to 0.3 mm thin, the tension of the rubber may be insufficient to fix the rubber by fitting alone without adhesive 30, so it is particularly preferable to use adhesive 30. Once the rubber layer 12 is formed as described above, the rubber roller 10 is completed.

[0023] According to this embodiment, a rubber roller 10 with a rubber layer thickness of 0.2 to 0.3 mm, which is unprecedented, can be provided. For example, in rollers placed on the transfer belt of a tandem-type color image forming apparatus, environmental dimensional changes (dimensional changes due to temperature and humidity) can be a problem. However, in the rubber roller 10 of this embodiment, since the thickness of the rubber layer 12 is 0.2 to 0.3 mm, environmental dimensional changes can be significantly suppressed compared to conventional rubber rollers with a rubber layer thickness of 0.5 mm or more. Furthermore, as described above, since the rubber cylinder 12A and the metal shaft 11 are fixed with adhesive 30 before the rubber cylinder 12A is shaved, rotation of the rubber cylinder 12A relative to the metal shaft 11 can be suppressed when the rubber cylinder 12A is shaved to a thinness of 0.2 to 0.3 mm. Moreover, as described above, since the concentrated areas S of the adhesive 30 are dispersed on the outer surface of the metal shaft 11, it is possible to improve the conductivity of the rubber roller 10 compared to when the adhesive 30 is evenly applied to the entire surface. Furthermore, since the adhesive material 30 is dispersed and scattered, for example, when reusing the metal shaft 11, it becomes easier to peel off the rubber layer 12, and it also becomes easier to peel off the adhesive material 30 from the metal shaft 11.

[0024] [Other embodiments] In the above embodiment, the rubber layer 12 of the rubber roller 10 was conductive, but the rubber layer 12 can be made non-conductive.

[0025] In the above embodiment, the layer covering the metal shaft 11 was a rubber layer 12, but this layer can also be a foamed resin layer. [Examples]

[0026] The embodiments described above will be further explained below with reference to examples and comparative examples, but the rubber roller 10 of this disclosure is not limited to the following examples. The rubber rollers of the examples and comparative examples were evaluated for electrical resistance, environmental dimensional change, processability, etc. (see Figure 11).

[0027] (1) Rubber rollers of the examples and comparative examples In each example and each comparative example, the shape and size of the rubber roller and the metal shaft 11 have the same configuration, and the material of the rubber roller is the same as that of the first embodiment, but the carbon content of the rubber layer 12 is partially different. In each example and each comparative example, the thickness of the adhesive material 30 (the thickness at the concentrated portion S), the bubble diameter of the foam 41 of the coating roller 40 used in the adhesive material coating process, etc. are different (see Fig. 11). Note that the size of the portion (large diameter portion 11A) covered with the rubber layer 12 on the metal shaft 11 is 24.0 mm in diameter and 18 mm in axial length. The following are used for the rubber of the rubber layer 12 and the carbon. EPDM1; manufactured by Mitsui Chemicals, Inc., trade name "EPT4045" EPDM2; manufactured by Mitsui Chemicals, Inc., trade name "X-3042E" Carbon; manufactured by Asahi Carbon Co., Ltd., trade name "Asahi #60UG"

[0028] (2) Test method <Rubber layer thickness, adhesive layer thickness> Measured in an environment of temperature 22°C and humidity 55%.

[0029] <JIS-A hardness> The JIS-A hardness of the rubber layer 12 was measured based on JIS K6253-3.

[0030] <Bubble diameter of the foam of the coating roller> Using a microscope, the bubble diameters of 20 bubbles were measured at a magnification of 50 times, and their average value was calculated. When the bubbles are non-circular, the bubble diameter is the distance between the two farthest points on the contour of the bubble.

[0031] <Environmental dimension change> The change in the outer diameter of the rubber layer 12 due to the change in temperature and humidity was measured. The value obtained by subtracting the outer diameter of the rubber layer 12 in an environment of temperature 32°C and humidity 80% from the outer diameter of the rubber layer 12 in an environment of temperature 10°C and humidity 15% was taken as the value of the environmental dimension change. When this value is 0.025 or less, it is evaluated as ○, and when it is greater than 0.025, it is evaluated as ×.

[0032] <Electrical resistance value> As shown in Figure 10 (resistance measurement), a load of 500gf is applied to both ends (small diameter portion 11B) of the conductive rubber roller 10 to press the rubber layer 12 against the metal (SUS) plate 50. The metal shaft 11, the metal plate 50, a 1000Ω resistor (R2), and a 5V power supply V1 are connected in series, and the circuit 51 is energized. The voltage (V2) across the 1000Ω resistor (R2) is measured to calculate the electrical resistance value (R1) of the conductive rubber roller (10). The electrical resistance value is evaluated as follows: ◎ if it is 5logΩ or less, ○ if it is greater than 5logΩ and 6logΩ or less, and × if it is greater than 6logΩ.

[0033] <Workability> In the rubber processing process, the resistance to tearing of the rubber cylinder 12A during machining was checked and evaluated in two stages. A "×" indicates that it was easily torn, while a "○" indicates that it performed better.

[0034] (3) Evaluation results As shown in Figure 11, in Examples 1 to 8, where the thickness of the rubber layer 12 was 0.2 to 0.3 mm, the environmental dimensional change was good (less than 0.025 mm), and the processability was also good. Furthermore, in Examples 1 to 7, where the thickness of the adhesive 30 was 5 to 25 μm, the electrical resistance value was also good, at 5 log Ω or less.

[0035] <Note> The following describes the features extracted from the above embodiment, explaining their effects and other aspects as needed.

[0036] For example, the following features of this disclosure relating to conductive rubber rollers and methods for manufacturing the same can be considered to have been conceived with the objective of "providing a novel rubber roller," given the background art that, for example, "rubber rollers in which a metal shaft is covered with a rubber layer are known (see, for example, Japanese Patent Application Publication No. 2013-156299 (paragraph

[0046] , etc.))." There has been a long-standing demand for novel rubber rollers and novel methods for manufacturing rubber rollers.

[0037] [Feature 1] A method for manufacturing a conductive rubber roller comprising a conductive metal shaft and a conductive rubber layer covering its outer surface, The process includes applying a liquid adhesive to the outer surface of the metal shaft, After the liquid adhesive dries, a rubber cylinder fitting step is performed in which a conductive rubber cylinder is fitted to the outside of the metal shaft. The process includes a rubber processing step of polishing or cutting the rubber cylinder until it is 0.2 to 0.3 mm thick to form the rubber layer, A method for manufacturing a conductive rubber roller, wherein in the adhesive coating step, the liquid adhesive is applied to the outer surface of the metal shaft such that concentrated areas of the liquid adhesive are dispersed and scattered.

[0038] [Feature 2] The method for manufacturing a conductive rubber roller according to Feature 1, wherein the diameter of the adhesive material after drying at the concentrated area is 50 to 300 μm and the thickness is 5 to 25 μm.

[0039] [Feature 3] The method for manufacturing a conductive rubber roller according to feature 1, wherein in the adhesive coating step, the liquid adhesive is applied to the outer surface of the metal shaft by foam with a bubble diameter of 50 to 200 μm.

[0040] [Feature 4] A method for manufacturing a conductive rubber roller comprising a conductive metal shaft and a conductive rubber layer covering its outer surface, The process includes applying a liquid adhesive to the outer surface of the metal shaft, The process includes a rubber cylinder fitting step in which, after the liquid adhesive has dried, a conductive rubber cylinder is fitted onto the outside of the metal shaft. A method for manufacturing a conductive rubber roller, wherein in the adhesive coating step, the liquid adhesive is applied to the outer surface of the metal shaft by foam with a bubble diameter of 50 to 200 μm.

[0041] [Feature 5] A method for manufacturing a conductive rubber roller comprising a conductive metal shaft and a conductive rubber layer covering its outer surface, The process includes applying a liquid adhesive to the outer surface of the metal shaft, After the liquid adhesive dries, a rubber cylinder fitting step is performed in which a conductive rubber cylinder is fitted to the outside of the metal shaft. The process includes a rubber processing step of polishing or cutting the rubber cylinder until it is 0.2 to 0.3 mm thick to form the rubber layer, A method for manufacturing a conductive rubber roller, wherein in the adhesive coating step, the liquid adhesive is applied to the outer surface of the metal shaft by foam with a bubble diameter of 50 to 200 μm.

[0042] [Feature 6] The method for manufacturing a conductive rubber roller according to any one of features 3 to 5, wherein the foam is pressed against the metal shaft and contacts it in a concave state when the liquid adhesive is applied.

[0043] [Feature 7] A method for manufacturing a conductive rubber roller according to any one of features 1 to 6, wherein the liquid adhesive is dried by blowing air onto the liquid adhesive.

[0044] [Feature 8] As the aforementioned metal shaft, an aluminum one is used. As the adhesive, an acrylic adhesive diluted with a solvent is used. A method for manufacturing a conductive rubber roller according to any one of features 1 to 7, wherein the rubber layer is made of EPDM containing carbon.

[0045] [Feature 9] A conductive rubber roller comprising a conductive metal shaft and a conductive rubber layer covering its outer surface, The rubber layer is provided with an adhesive material for fixing it to the metal shaft, A conductive rubber roller having a rubber layer thickness of 0.2 to 0.3 mm.

[0046] [Feature 10] The rubber layer is made of EPDM containing carbon, and the JIS-A hardness of the rubber layer is 70 to 80. The concentrated areas of the adhesive are scattered and dispersed on the outer surface of the metal shaft. The conductive rubber roller according to feature 9, wherein the resistance value of the conductive rubber roller is 5.0 log Ω or less.

[0047] Based on the above features, a novel rubber roller is provided.

[0048] While this specification and drawings disclose specific examples of the technology included in the claims, the technology described in the claims is not limited to these specific examples, but also includes various modifications and changes to these examples, as well as parts of the examples taken individually. [Explanation of Symbols]

[0049] 10 Conductive rubber roller (rubber roller) 11 Metal shaft 11A Large diameter section 11B Small diameter section 12 Rubber layer 12A rubber tube 30 Adhesive 40 Application roller 41 Foam 42 bubbles S concentrated area

Claims

1. A method for manufacturing a conductive rubber roller comprising a conductive metal shaft and a conductive rubber layer covering its outer surface, The process includes applying a liquid adhesive to the outer surface of the metal shaft, After the liquid adhesive dries, a rubber cylinder fitting step is performed in which a conductive rubber cylinder is fitted to the outside of the metal shaft. The process includes a rubber processing step of polishing or cutting the rubber cylinder to a thickness of 0.2 to 0.3 mm to form the rubber layer, A method for manufacturing a conductive rubber roller, wherein in the adhesive coating step, the liquid adhesive is applied to the outer surface of the metal shaft such that concentrated areas of the liquid adhesive are dispersed and scattered.

2. The method for manufacturing a conductive rubber roller according to claim 1, wherein the diameter of the adhesive material after drying at the concentration point is 50 to 300 μm and the thickness is 5 to 25 μm.

3. The method for manufacturing a conductive rubber roller according to claim 1, wherein in the adhesive coating step, the liquid adhesive is applied to the outer surface of the metal shaft by a foam with a bubble diameter of 50 to 200 μm.

4. A method for manufacturing a conductive rubber roller comprising a conductive metal shaft and a conductive rubber layer covering its outer surface, The process includes applying a liquid adhesive to the outer surface of the metal shaft, After the liquid adhesive dries, a rubber cylinder fitting step is performed in which a conductive rubber cylinder is fitted to the outside of the metal shaft. The process includes a rubber processing step of polishing or cutting the rubber cylinder to a thickness of 0.2 to 0.3 mm to form the rubber layer, A method for manufacturing a conductive rubber roller, wherein in the adhesive coating step, the liquid adhesive is applied to the outer surface of the metal shaft by foam with a bubble diameter of 50 to 200 μm.

5. The method for manufacturing a conductive rubber roller according to claim 3 or 4, wherein the foam is an application roller that is pressed against the metal shaft and contacts it in a concave state when the liquid adhesive is applied.

6. A conductive rubber roller comprising a conductive metal shaft and a conductive rubber layer covering its outer surface, The rubber layer is provided with an adhesive material for fixing it to the metal shaft, A conductive rubber roller having a rubber layer thickness of 0.2 to 0.3 mm.

7. The rubber layer is made of EPDM containing carbon, and the JIS-A hardness of the rubber layer is 70 to 80. The concentrated areas of the adhesive are scattered and dispersed on the outer surface of the metal shaft. The conductive rubber roller according to claim 6, wherein the resistance value of the conductive rubber roller is 5.0 log Ω or less.

Images