Method for manufacturing rubber molded body, rubber molded body, fixing roller, and fixing device

Abstract

To provide a method for manufacturing a rubber molded body excellent in productivity, and provide a rubber molded body having a large circularity of void, and a fixing roller and a fixing device using the rubber molded body.SOLUTION: A method for manufacturing a rubber molded body 12 includes steps of: mixing a silicone rubber, water-soluble particles, and an open-cell forming agent to obtain a silicone rubber composition; curing the silicone rubber composition to obtain a cured body; and eluting the water-soluble particles from the cured body. The melting point of the water-soluble particles is lower than the temperature at which the silicone rubber composition is cured. The rubber molded body has a void 3 in a structure. The void 3 has circular void portions 1 and linear void portions 2. The circularity of the circular void portion 1 is 0.9 or more, and the circular void portions 1 are connected to each other via the linear void portion 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a rubber formed body, a rubber formed body, a fixing roller, and a fixing device. [Background technology]

[0002] Conventionally, fixing rollers using a rubber-formed body (sponge) containing silicone rubber have been used in fixing devices in image forming devices such as copiers, printers, and facsimiles. A simple method for obtaining a sponge for use in a fixing roller involves kneading silicone rubber to which water-soluble particles have been added, and then dissolving the water-soluble particles in water to create voids (see, for example, Patent Documents 1 and 2). Conventionally, examples of water-soluble particles used include table salt and sucrose.

[0003] However, in the method using salt or sucrose as the water-soluble particles, it takes several hours to dissolve the water-soluble particles, which is problematic in terms of productivity. Furthermore, when salt or sucrose is used as the water-soluble particles, the shape of the salt or sucrose is directly reflected in the voids of the rubber-formed body. This results in a problem that the voids of the rubber-formed body become distorted, adversely affecting durability. Therefore, it is desirable to increase the circularity of the voids. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-8990 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-74690 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a method for producing a rubber molded article with excellent productivity. Another object of the present invention is to provide a rubber formed body having voids with a large degree of circularity, and a fixing roller and fixing device using the same. [Means for solving the problem]

[0006] The above-mentioned problems of the present invention can be solved by the following means.

[0007] (1) A method for producing a rubber-formed body, comprising the steps of: mixing silicone rubber, water-soluble particles, and an open-cell agent to form a silicone rubber composition; curing the silicone rubber composition to form a cured body; and eluting the water-soluble particles from the cured body, wherein the melting point of the water-soluble particles is lower than the temperature at which the silicone rubber composition is cured.

[0008] (2) The method for producing a rubber molded article according to (1) above, wherein the melting point of the water-soluble particles is 0°C or higher and lower than 130°C.

[0009] (3) The method for producing a rubber molded article according to (1) above, wherein the melting point of the water-soluble particles is greater than 70°C and not greater than 110°C.

[0010] (4) The method for producing a rubber molded article according to (1) or (2), wherein the solubility of the water-soluble particles in water at 25°C is 0.1 g / mL or more.

[0011] (5) The method for producing a rubber molded body according to (1) or (2), wherein the water-soluble particles are one or more of fructose, maltose, and ribose.

[0012] (6) The method for producing a rubber molded body according to (1) or (2), wherein the water-soluble particles are classified using a sieve.

[0013] (7) A rubber formed body having voids within its structure, the voids having circular void portions and linear void portions, the circular void portions having a circularity of 0.9 or more, and the circular void portions being connected to each other via the linear void portions.

[0014] (8) The rubber molded body according to (7) above, characterized in that the ASKER C hardness is 30 or more and 50 or less.

[0015] (9) A fixing roller having the rubber forming body according to (7) or (8).

[0016] (10) A fixing device having the fixing roller described in (9) above. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a method for manufacturing a rubber formed body with excellent productivity, and also to provide a rubber formed body having voids with high circularity, and a fixing roller and fixing device using the same. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a schematic diagram illustrating an example of a fixing device according to an embodiment. [Figure 2] 2 is a schematic diagram showing the open cell state of voids in the rubber forming body of the embodiment. FIG. [Figure 3] FIG. 2 is a schematic diagram showing a normal open cell state of voids in a rubber forming body. [Figure 4] 3 is a schematic diagram illustrating a method for measuring the circularity of voids in a rubber forming body according to an embodiment. FIG. [Figure 5] 1 is a flowchart showing a method for manufacturing a rubber formed body according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail, but the embodiments of the present invention are not limited to the embodiments described below. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in the embodiments are merely examples and are not intended to limit the scope of the present invention. The sizes and positional relationships of components shown in each drawing may be exaggerated or simplified for clarity. Furthermore, some elements may be omitted to avoid overly complicated drawings.

[0020] First, the fixing device and the fixing roller used in this fixing device will be described with reference to the drawings as needed, and then the rubber forming body used in this fixing roller will be described.

[0021] [Fuser and Fuser Roller] The fixing device is a device used in an image forming apparatus such as a copier, a printer, a facsimile, etc. As shown in FIG.

[0022] The fixing roller 10 is a member that fixes toner to a recording medium 50, such as printed paper or printed film. The fixing roller 10 has a cylindrical core 11 and a rubber former 12, which is a coating layer disposed on the outer periphery of the core 11. Examples of materials for the core 11 include metal materials such as aluminum, iron, and SUS. The rubber former 12, which is a coating layer, will be described later.

[0023] The pressure roller 20 is a member that presses the recording medium 50 against the fixing roller 10. The pressure roller 20 has a cylindrical core material 21 and a coating layer 22 that is disposed on the outer periphery of the core material 21. Examples of the core material 21 include metal materials such as aluminum, iron, and SUS. Examples of the coating layer 22 include silicone rubber.

[0024] The heating roller 30 is a member that heats the fixing belt 40. The heating roller 30 has a cylindrical core material 31 and a coating layer 32 that is disposed on the outer periphery of the core material 31. Examples of the core material 31 include metal materials such as aluminum, iron, and SUS. Examples of the coating layer 32 include polytetrafluoroethylene (PTFE). The heating roller 30 has a heat source such as a heater (not shown) disposed inside it. The heating roller 30 heats the fixing belt 40 using this heat source.

[0025] The fixing device 100 rotates the fixing roller 10 and the pressure roller 20, thereby bringing the fixing belt 40 into contact with the recording medium 50 conveyed between the fixing roller 10 and the pressure roller 20. A toner image has been transferred onto the recording medium 50. The fixing device 100 then heats and pressurizes the toner image at a predetermined fixing temperature, thereby fixing the toner image to the recording medium 50.

[0026] [Rubber former] As shown in Figure 2, the rubber former 12 is a sponge having voids 3 within its structure. The voids 3 include circular voids 1 and linear voids 2. In the rubber former 12, the circular voids 1 have a circularity of 0.9 or more, and the circular voids 1 are connected to each other via the linear voids 2. The rubber former 12 is a sponge used in a fixing roller of a fixing device in an image forming apparatus, and is made primarily of silicone rubber.

[0027] In the rubber forming body 12, the circular voids 1 are connected to each other via the linear voids 2. That is, the circular voids 1 are connected to each other via lines. As a result, in the rubber forming body 12, the circular voids 1 are in an open-cell state via the linear voids 2. As shown in FIG. 3 , in a rubber forming body 1000 that is in a normal open-cell state, the voids 1001 are in contact with each other at their outer edges. That is, in this case, the voids 1001 are in contact with each other at points. As a result, in the rubber forming body 1000, the voids 1001 are in an open-cell state. In the rubber forming body 12 of this embodiment, the circular voids 1 are in an open-cell state via the linear voids 2, so that the circular voids 1 are separated from each other by a predetermined interval. As a result, the circular voids 1 are easily dispersed within the structure of the rubber forming body 12, making it easier to uniformize the hardness and elasticity of the rubber forming body 12.

[0028] Here, in the rubber formation 1000, the voids 1001 being in contact with each other at points refers to a state in which, when the cross section of the rubber formation 1000 is observed with an optical microscope or an SEM photograph, the voids 1001 are adjacent to each other, forming a continuous void 1001. In addition, in the rubber formation 12, the circular voids 1 being in contact with each other along a line refers to a state in which, when the cross section of the rubber formation 12 is observed with an optical microscope or an SEM photograph, it is not possible to confirm that the voids (here, the circular voids 1) are adjacent to each other, but holes can be visually confirmed within the voids 3, indicating that they are open cells. Note that, when the cross section of the rubber formation 12 is observed with an optical microscope or an SEM photograph, the linear voids 2 connecting the circular voids 1 appear to be holes.

[0029] The circularity of the circular void 1 is 0.9 or more. If the circularity of the circular void 1 is 0.9 or more, the rubber forming body 12 can have a void (circular void 1) with a shape (spherical) that is almost free of distortion. This prevents excessive stress concentration in one part of the rubber forming body 12, improving the durability of the rubber forming body 12. From the viewpoint of achieving a shape (spherical) with less distortion, the circularity of the circular void 1 is preferably 0.95 or more, more preferably 1.0. In this embodiment, the circularity of the circular void 1 is calculated by sandwiching the circular void 1 between two concentric circles and calculating the ratio of the diameters of the two concentric circles. That is, as shown in FIG. 4, the circularity of the circular void 1 is calculated by dividing the minimum diameter D1 by the maximum diameter D2 of the two concentric circles.

[0030] Specifically, the circularity of the circular void 1 in this embodiment is calculated by the following method. First, a cross section of the rubber formed body 12 is cut out and observed using an optical microscope or SEM photograph. Next, the circular void 1 is sandwiched between two concentric circles. Next, the ratio of the diameters of the two concentric circles (minimum diameter ÷ maximum diameter) is calculated. Using this method, five circular voids 1 are measured in descending order of size, and the average value is taken as the circularity. The maximum diameter D2 when the circular gap 1 is sandwiched between two concentric circles is, for example, 5 μm or more and 50 μm or less. The circularity of the circular cavity 1 can be controlled by using water-soluble particles with a predetermined melting point in the manufacturing process, as will be described later.

[0031] The linear voids 2 are voids that connect the circular voids 1 among the voids 3 formed in the rubber forming body 12. The linear voids 2 are connected to the circular voids 1 and formed linearly. Here, "linear" includes the linear voids 2 having a predetermined width W in a direction perpendicular to the direction extending toward the circular voids 1, for example. In other words, the linear voids 2 are linear or strip-shaped portions of the voids 3. As described above, when the cross section of the rubber forming body 12 is observed with an optical microscope or an SEM photograph, the linear voids 2 appear as holes. The width W (maximum width) of the linear voids 2 is, for example, 1 μm or more and 10 μm or less.

[0032] The boundary between the linear void portion 2 and the circular void portion 1 is not clearly defined. However, for example, when the outer edge of the circular void portion 1 is extended to form a circle at the connection portion of the linear void portion 2, the boundary can be the connection portion between this extended outer edge portion and the linear void portion 2. In other words, when the linear void portion 2 does not exist, the connection portion between the outer edge of the circular void portion 1 and the linear void portion 2 can be the boundary.

[0033] The distance between the circular voids 1 connected to both ends of the linear void 2 is not particularly limited, but for example, the shortest distance between the boundaries of the linear void 2 and the circular void 1 can be 1 μm or more and 100 μm or less. Furthermore, the circular void 1 may be connected to one linear void 2, but may also be connected to two or more linear voids 2. The linear voids 2 are formed by using an open-cell agent in the manufacturing process, as will be described later.

[0034] The rubber former 12 preferably has an ASKER C hardness of 30 or more and 50 or less. If the ASKER C hardness is 30 or more, the strength of the rubber former 12 is improved, and the durability of the rubber former 12 is improved. From the viewpoint of improving the durability of the rubber former 12, the ASKER C hardness of the rubber former 12 is more preferably 33 or more, and even more preferably 37 or more. On the other hand, if the ASKER C hardness is 50 or less, it becomes easier to increase the deformation amount of the fixing roller 10 when supplying the recording medium 50 to the fixing device 100, and it becomes easier to increase the nip width. This makes it easier for the fixing device 100 to apply a uniform pressure to the recording medium 50. From the viewpoint of applying a uniform pressure to the recording medium 50, the ASKER C hardness of the rubber former 12 is more preferably 47 or less, and even more preferably 42 or less. The ASKER C hardness of the rubber formed body 12 is measured, for example, in accordance with JIS K7312:1996 using an ASKER (registered trademark) rubber hardness meter (durometer) C type (manufactured by Kobunshi Keiki Co., Ltd.). The ASKER C hardness of the rubber former 12 can be controlled by adjusting the amount of water-soluble particles added in the manufacturing process, as will be described later.

[0035] [Method of manufacturing rubber molded body] Next, the method for producing the rubber formed body of this embodiment will be described with reference to the drawings as appropriate. The method for producing the rubber formed body 12 includes the steps of mixing silicone rubber, water-soluble particles, and an open-cell agent to form a silicone rubber composition, curing the silicone rubber composition to form a cured body, and eluting the water-soluble particles from the cured body, wherein the melting point of the water-soluble particles is lower than the temperature at which the silicone rubber composition is cured.

[0036] As shown in FIG. 5, the method for producing the rubber formed body 12 will be described as including a silicone rubber composition production step S11, a cured body production step S12, and an elution step S13.

[0037] (Silicone rubber composition manufacturing process) The silicone rubber composition production step S11 is a step in which silicone rubber, water-soluble particles, and an open-cell agent are mixed together to form a silicone rubber composition.

[0038] As the silicone rubber, a liquid silicone rubber is used. Any silicone rubber may be used as long as it is liquid at room temperature and hardens naturally at room temperature or hardens by heating to become rubbery. That is, the silicone rubber may be a condensation type silicone rubber or an addition type silicone rubber. Examples of silicone rubber include addition type silicone rubbers that harden at temperatures between 80°C and 130°C. However, the silicone rubber may be selected appropriately depending on the melting point of the water-soluble particles used.

[0039] The water-soluble particles used have a melting point lower than the temperature at which the silicone rubber composition is cured. That is, the water-soluble particles used melt at a temperature lower than the heating temperature (vulcanization temperature) in the cured body production step S12. This makes it easier to elute the water-soluble particles from the cured body in the elution step S13. Furthermore, during molding at the set temperature in the cured body production step S12, the water-soluble particles liquefy before the silicone rubber is completely cured. By liquefying the water-soluble particles before the silicone rubber is completely cured, the water-soluble particles become spherical due to the surface tension between the silicone rubber and the water-soluble particles. This allows the circularity of the circular void portion 1 of the rubber formed body 12 to be 0.9 or more.

[0040] The water-soluble particles preferably have a melting point of 0°C or higher and lower than 130°C. If the melting point of the water-soluble particles is lower than 130°C, the water-soluble particles melt at 130°C or higher, which is the general vulcanization temperature condition in the cured body production step S12. The melting point of the water-soluble particles is more preferably higher than 70°C and lower than 110°C. If the melting point of the water-soluble particles is higher than 70°C, the water-soluble particles do not melt at 70°C or lower, which is the general temperature during mixing in the silicone rubber composition production step S11. The melting point of the water-soluble particles is more preferably 80°C or higher, from the viewpoint of preventing melting in the silicone rubber composition production step S11. On the other hand, if the melting point of the water-soluble particles is 110°C or lower, the water-soluble particles are more likely to melt when the vulcanization temperature in the cured body production step S12 is set to 130°C. The melting point of the water-soluble particles is more preferably 100°C or lower, from the viewpoint of facilitating melting in the cured body production step S12.

[0041] The melting point of the water-soluble particles can be measured by DSC (Differential Scanning Calorimetry). The sample is heated from 0°C to 200°C at a rate of 10°C / min, and the peak obtained is taken as the melting point. The melting point of the water-soluble particles can be measured using a known DSC measuring device (for example, Diamond DSC, manufactured by PerkinElmer).

[0042] The solubility of the water-soluble particles in water is preferably 0.1 g / mL or more at 25°C. If the solubility of the water-soluble particles in water is 0.1 g / mL or more at 25°C, the water-soluble particles will be more easily eluted in the elution step. From the viewpoint of making the elution of the water-soluble particles easier, the solubility of the water-soluble particles in water is more preferably 0.3 g / mL or more at 25°C, and even more preferably 0.5 g / mL or more at 25°C. There is no particular upper limit, but the solubility of the water-soluble particles in water may be, for example, 3.7 g / mL or less at 25°C, or 2 g / mL or less at 25°C.

[0043] The solubility of water-soluble particles in water is calculated in accordance with JIS K8001:2017 from the volume (mL) of water required for dissolution within 30 minutes when the particles are vigorously shaken for 30 seconds every 5 minutes at 25°C.

[0044] The water-soluble particles are preferably one or more of fructose, maltose, and ribose. By using one or more of these as the water-soluble particles, the water-soluble particles are more easily eluted in the elution step. From the viewpoint of making the water-soluble particles more easily eluted, the water-soluble particles are more preferably one or more of maltose and ribose, and even more preferably ribose.

[0045] The water-soluble particles are preferably classified using a sieve. By classifying the water-soluble particles using a sieve, the circular voids 1 of the rubber former 12 can be made to have a uniform size.

[0046] Triethylene glycol can be used as the open-cell agent. In the method for producing the rubber formed body 12, the open-cell agent is used so that the open-cell agent penetrates between the water-soluble particles, forming passages through which the water-soluble particles can be eluted. This allows the water-soluble particles to be eluted in the elution step S13. Furthermore, these passages become the linear voids 2 of the rubber formed body 12.

[0047] In the silicone rubber composition production step S11, for example, 50 parts by mass of silicone rubber / A are first blended with 5 to 50 parts by mass of an open-cell agent, and the mixture is mixed under conditions of 25 to 120°C and 1 to 5 minutes. Next, 70 to 200 parts by mass of water-soluble particles classified using a 50 μm sieve are added, and the mixture is mixed under conditions of 25 to 70°C and 1 to 5 minutes. Furthermore, 50 parts by mass of silicone rubber / B are added, and the mixture is mixed under conditions of 25 to 90°C and 1 to 5 minutes to obtain a silicone rubber composition. The silicone rubber composition is then degassed under reduced pressure. Note that the degassing of the silicone rubber composition under reduced pressure may be performed after the silicone rubber composition is poured into the space between the mold and the mandrel, as described below.

[0048] (cured body manufacturing process) The cured product production step S12 is a step of curing the silicone rubber composition to form a cured product, that is, the cured product production step S12 is a step of vulcanizing the silicone rubber composition. In the cured body production step S12, for example, a metal mandrel made of aluminum with a primer applied to its outer periphery is first placed in a cylindrical mold. Next, the silicone rubber composition degassed under reduced pressure in the silicone rubber composition production step S11 is poured between the mold and the mandrel. After pouring, the temperature is raised to 100°C or higher and 250°C or lower, and the silicone rubber composition is cured by heating for 0.5 hours to 12 hours. This vulcanizes the silicone rubber composition.

[0049] (Elution process) The elution step S13 is a step of eluting the water-soluble particles from the cured body. In the elution step S13, the cured body is immersed in water and pressurized to remove the water-soluble particles from the cured body, thereby forming a rubber-formed body 12. In the leaching step S13, for example, after the silicone rubber composition is cured in the cured body production step S12, the cured body is quickly immersed in warm water at 40°C to 100°C while being kneaded for 5 to 30 minutes. This causes the water-soluble particles to flow out of the cured body. The cured body from which the water-soluble particles have been released is then removed from the warm water to form the rubber formed body 12.

[0050] In conventional methods for producing rubber molded bodies, the melting point of the water-soluble particles is 130°C or higher, and the water-soluble particles are in a solid state immediately after molding the silicone rubber composition. Therefore, it takes several hours for the water-soluble particles to diffuse into water during the elution process. In contrast, the method for producing rubber molded bodies of the present embodiment uses water-soluble particles with a melting point lower than the temperature at which the silicone rubber composition is cured. That is, the method for producing rubber molded bodies of the present embodiment uses water-soluble particles with a low melting point, so the water-soluble particles are in a liquid state immediately after molding the silicone rubber composition. Therefore, if the water-soluble particles are eluted promptly immediately after molding the silicone rubber composition, they will be easily discharged into water, and the elution time is expected to be significantly reduced. This can improve productivity.

[0051] If necessary, the cured product removed from the hot water may be heated at 200°C to 250°C for 1 hour to 12 hours to subject the silicone rubber to secondary vulcanization. [Example]

[0052] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. A rubber molded body was produced by the following method: In Table 1, Nos. 1 to 5 are examples that satisfy the range of the present invention, and Nos. 6 to 8 are comparative examples that do not satisfy the range of the present invention.

[0053] [No.1] 50 parts by mass of silicone rubber (LSR7030 / A) and 20 parts by mass of triethylene glycol were kneaded for 3 minutes using a planetary kneader. 110 parts by mass of maltose (Wako special grade) classified through a 50 μm sieve was added and kneaded for 2 minutes. 50 parts by mass of silicone rubber (LSR7030 / B) was added and kneaded for 3 minutes to obtain a silicone rubber composition.

[0054] The silicone rubber composition was placed in a mold (φ29) for compression set measurement as specified in JIS K6262:2013 and degassed under reduced pressure. The silicone rubber composition was then heated at 130°C for 1 hour to cure. Immediately after curing, the silicone rubber composition was immersed in warm water at 60°C while being kneaded for approximately 5 minutes. The composition was removed from the water and heated at 200°C for 4 hours to secondary vulcanize the silicone rubber, yielding a rubber molded body.

[0055] [No.2~5, No.6~8] A rubber molded body was produced in the same manner as in Example 1, except for changing the conditions shown in Table 1. However, after all the water-soluble particles had been eluted, the silicone rubber was subjected to secondary vulcanization. The water-soluble particles shown in Table 1 were Wako special grade.

[0056] The water-soluble particles were measured for the following items. (Water solubility of water-soluble particles) The water solubility of water-soluble particles was measured by measuring the solubility of the particles in water, which was calculated from the volume (mL) of water required for dissolution within 30 minutes when the particles were vigorously shaken for 30 seconds every 5 minutes at 25°C, in accordance with JIS K8001:2017.

[0057] (Melting point of water-soluble particles) The melting point of the water-soluble particles was measured using a DSC measuring device (Diamond DSC, manufactured by PerkinElmer Co., Ltd.) Specifically, the sample was heated from 0°C to 200°C at a rate of 10°C / min, and the resulting peak was taken as the melting point.

[0058] The obtained rubber molded bodies were evaluated for the following items. (ASKER C hardness) The ASKER C hardness of the rubber formed body was measured in accordance with JIS K7312:1996 using an ASKER (registered trademark) rubber hardness meter (durometer) C type (manufactured by Kobunshi Keiki Co., Ltd.).

[0059] (Circularity of the gap) The circularity of the void portion was measured by the method described above with reference to Figure 4. First, a cross section of the rubber molded body was cut out and observed under an optical microscope. Next, the circular void portion was sandwiched between two concentric circles. Next, the ratio of the diameters of the two concentric circles (minimum diameter ÷ maximum diameter) was calculated. Using this method, five voids were measured in descending order of size, and the average value was taken as the circularity.

[0060] (Dissolution of water-soluble particles) Regarding the elution of water-soluble particles, when the silicone rubber composition was immersed in warm water at 60°C while being kneaded for about 5 minutes, if all of the water-soluble particles were eluted, it was judged as "Good", indicating that the elution of water-soluble particles was possible in a short period of time; if all of the water-soluble particles were not eluted and some or all of the water-soluble particles remained, it was judged as "Poor", indicating that the elution of water-soluble particles was not possible in a short period of time. These results are shown in Table 1.

[0061] [Table 1]

[0062] As shown in Table 1, Nos. 1 to 5 had high circularity of the voids (circular voids). Furthermore, the water-soluble particles were able to be dissolved in a short time. Furthermore, Nos. 1 to 3 had an appropriate amount of water-soluble particles added, so their ASKER C hardness was within the preferred range. No. 4 had a lower ASKER C hardness than Nos. 1 to 3 because the amount of water-soluble particles added was high. No. 5 had a higher ASKER C hardness than Nos. 1 to 3 because the amount of water-soluble particles added was low.

[0063] In Nos. 6 to 8, the water-soluble particles had high melting points, so the circularity of the voids (circular voids) was low, and it was impossible to dissolve the water-soluble particles in a short time. It took 15 hours for No. 6, 15 hours for No. 7, and 15 hours for No. 8 for all the water-soluble particles to dissolve.

[0064] Although the embodiments of the present invention have been described above in more detail, the scope of the present invention is not limited to these descriptions and should be broadly interpreted based on the claims. Furthermore, various changes and modifications based on these descriptions are also included in the scope of the present invention. For example, the method for producing a rubber molded body may include other steps between, before, or after the steps (S11 to S13) as long as they do not adversely affect the steps. For example, a step of removing foreign matter that has been mixed in during production may be included. [Explanation of symbols]

[0065] 1 Circular cavity 2 Linear void 3 void 10 Fuser roller 11 Core material 12 Rubber former 20 Pressure roller 21 Core material 22 Covering layer 30 Heating roller 31 Core material 32 Covering layer 40 Fixing belt 50 Recording Media 100 Fixing device D1 Minimum diameter D2 Maximum diameter W width

Claims

1. a step of mixing silicone rubber, water-soluble particles, and an open-cell agent to form a silicone rubber composition; curing the silicone rubber composition to form a cured product; and a step of eluting the water-soluble particles from the cured body, A method for producing a rubber formed article, wherein the melting point of the water-soluble particles is lower than the temperature at which the silicone rubber composition is cured.

2. 2. The method for producing a rubber molded article according to claim 1, wherein the melting point of the water-soluble particles is 0°C or higher and lower than 130°C.

3. 2. The method for producing a rubber formed article according to claim 1, wherein the melting point of the water-soluble particles is greater than 70°C and not greater than 110°C.

4. 3. The method for producing a rubber molded article according to claim 1, wherein the water-soluble particles have a solubility in water of 0.1 g / mL or more at 25°C.

5. 3. The method for producing a rubber molded article according to claim 1, wherein the water-soluble particles are one or more of fructose, maltose, and ribose.

6. 3. The method for producing a rubber formed article according to claim 1, wherein the water-soluble particles are classified using a sieve.

7. A rubber formation having voids within its structure, the gap has a circular gap portion and a linear gap portion, A rubber formed body, characterized in that the circular voids have a circularity of 0.9 or more, and the circular voids are connected to each other via the linear voids.

8. 8. The rubber formed article according to claim 7, characterized in that the ASKER C hardness is 30 or more and 50 or less.

9. A fixing roller comprising the rubber forming body according to claim 7 or 8.

10. A fixing device comprising the fixing roller according to claim 9.

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