JP2010224333A - Elastic roller, fixing device for image forming apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elastic roller including a foam elastic layer having excellent durability, and a fixing device for an image forming apparatus and the image forming apparatus having excellent durability. <P>SOLUTION: The elastic roller 1A includes a silicone foam elastic layer 3 formed on the outer peripheral surface of a shaft 2. The silicone foam elastic layer 3 has a cell whose mean cell diameter is 200-400 μm, and the standard deviation of cell diameter of which is 150-250 μm. The fixing device for the image forming apparatus and the image forming apparatus include the elastic roller 1A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an elastic roller, a fixing device for an image forming apparatus, and an image forming apparatus. More specifically, the elastic roller includes a foamed elastic layer having excellent durability, and a fixing device for image forming apparatus having excellent durability. And an image forming apparatus.

  Various image forming apparatuses using an electrophotographic system are employed in printers such as laser printers and video printers, copiers, facsimiles, and multi-function machines thereof. Various image forming apparatuses include an elastic roller having a shaft body and an elastic layer formed on an outer peripheral surface thereof. Examples of such an elastic roller include a charging roller, a developing roller, a transfer roller, a pressure roller, a paper feed / conveying roller, a fixing roller, and a developer supply roller. These rollers usually include a shaft body, an elastic layer formed on the outer peripheral surface of the shaft body, and a coat layer formed on the outer peripheral surface of the elastic layer as desired.

  Among these rollers, for example, an elastic roller that contacts the developer such as a fixing roller, a pressure roller, and a developer supply roller has the elastic layer adjusted to have a small hardness so as to perform a desired function. As a method for adjusting the hardness of the elastic layer in this manner, for example, a method is known in which bubbles (sometimes referred to as cells) are formed in the elastic layer and the elastic layer is used as a foamed elastic layer.

  As a composition capable of forming such a foamed elastic layer, for example, Patent Document 1 discloses that “100 parts by weight of a vinyl group-containing organopolysiloxane, 0.1 to 20 parts by weight of an organohydrogenpolysiloxane, 3 to The composition for conductive sponge rolls containing 50 parts by weight, 0.5 to 10 parts by weight of a blowing agent and a catalytic amount of a platinum catalyst is described.

  In addition, as a method for producing an elastic roller provided with a foamed elastic layer, for example, Patent Document 2 discloses that “(A) conductive silicone rubber containing conductive carbon black, (B) a curing agent, and (C) a foaming agent. The composition to be contained is subjected to pressure vulcanization at a temperature of 90 to 170 ° C. so that the reaction rate of the crosslinking group is in the range of 1 to 80%, and then taken out of the mold, and further at a temperature of 140 to 300 ° C. A process for producing a conductive silicone rubber sponge characterized in that foaming and the remaining crosslinking reaction are carried out in a large mold or in hot air ”is described.

  If bubbles are formed in the elastic layer of the elastic roller to reduce the hardness of the elastic layer, the bubbles are easily broken during use, and the durability of the foamed elastic layer may be lowered. However, the life of image forming apparatuses has been extended by the recent promotion of environmental measures and the like, and it is necessary to extend the life of various rollers attached to the image forming apparatus. Therefore, the foamed elastic layer of the elastic roller is required to exhibit even higher durability while maintaining its low hardness.

JP-A-3-223345 JP-A-8-3356

  An object of this invention is to provide the elastic roller provided with the foaming elastic layer excellent in durability. Another object of the present invention is to provide a fixing device for an image forming apparatus and an image forming apparatus having excellent durability.

  The inventor of the present application has studied various effects of the foamed silicone rubber composition forming the foamed elastic layer on the durability of the foamed elastic layer. We found that the standard deviation was greatly involved. In order to adjust the average cell diameter and the standard deviation effective for exhibiting high durability of the foamed elastic layer, it is contained or adsorbed on the silicone rubber component and the filler which are the components of the foamed silicone rubber composition. We also found that water is important. Specifically, the inventor of the present application is able to achieve a low hardness of the foamed elastic layer, since the cells formed by foaming when the amount of water is below a specific amount are substantially uniform. It has been found that cell bubbling and destruction is prevented over a long period of time.

That is, as means for solving the above-mentioned problem,
Claim 1 is an elastic roller having a silicone foam elastic layer on the outer peripheral surface of the shaft body, wherein the silicone foam elastic layer has an average cell diameter of 200 to 400 μm and a standard deviation of the cell diameter of 150 to 250 μm. It is an elastic roller characterized by having a cell that is
According to a second aspect of the present invention, the silicone foamed elastic layer comprises a foamed silicone rubber composition containing a rubber composition comprising a silicone rubber component, a filler, and water of 0.050 mass% or less on the outer peripheral surface of the shaft body. The elastic roller according to claim 1, wherein the elastic roller is heat-cured.
A third aspect of the present invention is a fixing device for an image forming apparatus comprising the elastic roller according to the first or second aspect.
A fourth aspect of the present invention is an image forming apparatus comprising the elastic roller according to the first or second aspect.

  Since the foamed elastic layer of the elastic roller according to the present invention is formed with cells having an average cell diameter of 200 to 400 μm and a standard deviation of a cell diameter of 150 to 250 μm, without impairing the reduced hardness state, Cell foaming and destruction are reduced, and the initial cell formation state can be maintained for a long period of time. Therefore, according to this invention, the elastic roller provided with the foaming elastic layer excellent in durability can be provided.

  In addition, since the fixing device for an image forming apparatus and the image forming apparatus according to the present invention include the elastic roller according to the present invention, a decrease in durability due to deterioration of the elastic roller can be suppressed. Therefore, according to the present invention, it is possible to provide a fixing device for an image forming apparatus and an image forming apparatus having excellent durability.

FIG. 1 is a schematic perspective view showing an elastic roller which is an embodiment of the elastic roller according to the present invention. FIG. 2 is a schematic perspective view showing an elastic roller which is an embodiment of the elastic roller according to the present invention. FIG. 3 is a schematic view of the essential portions showing an example of the image forming apparatus according to the present invention. FIG. 4 is a schematic diagram showing a durability test apparatus.

  The elastic roller according to the present invention includes a shaft and a foamed elastic layer having cells having an average cell diameter of 200 to 400 μm and a standard deviation of the cell diameter of 150 to 250 μm. As described above, since the elastic roller includes the foamed elastic layer in which the cells having the average cell diameter in the range and the standard deviation in the range are formed, the breakage of the cells is achieved despite the low hardness. Bubbles and destruction are prevented, and the initial cell formation state can be maintained over a long period of time. That is, the elastic roller according to the present invention is provided with a foamed elastic layer having a low hardness and excellent durability.

  In the elastic roller according to the present invention, when the average cell diameter is less than 200 μm, it is necessary to excessively deform the foamed elastic layer in order to secure a certain nip width when mounted on the fixing device for an image forming apparatus. As a result, the cells formed in the foamed elastic layer may be easily broken and destroyed. On the other hand, if the average cell diameter of the cells exceeds 400 μm, the developer tends to enter and remain in the cells, and the cells may be easily broken and broken. The average cell diameter is preferably 230 to 380 μm, particularly preferably 250 to 350 μm, from the viewpoint that the durability of the foamed elastic layer can be further improved.

  In the elastic roller according to the present invention, when the standard deviation is less than 150 μm or more than 250 μm, the foamed elastic layer is not firmly bonded to the shaft body, and is near the outer periphery of the shaft body in the foamed elastic layer. The formed cell may be easily broken and destroyed. The standard deviation σ of the cell diameter is preferably 170 to 230 μm, and particularly preferably 180 to 210 μm, in terms of achieving both higher hardness and improved durability of the foamed elastic layer. preferable.

The average cell diameter of the cell is within the observation field by observing an area of about 20 mm ² with an electron microscope or the like on the surface of the foamed elastic layer or the cut surface when the foamed elastic layer is cut on an arbitrary surface. The maximum length of the opening in each cell is measured, and the measured maximum length (referred to as cell diameter) can be obtained as an average length obtained by arithmetic averaging. The standard deviation σ of the cell diameter can be obtained by the standard method by measuring the standard deviation σ of the cell diameter measured as described above. The average cell diameter and standard deviation σ in the cell can be adjusted by the blending amount of the foaming agent contained in the foamed silicone rubber composition described later, the curing conditions of the foamed silicone rubber composition, and the like. For example, when the curing conditions for the foamed silicone rubber composition to cure rapidly are selected, the average cell diameter and the standard deviation σ are usually small, and when the curing conditions for the foamed silicone rubber composition to cure gradually are selected, the average is usually The cell diameter and the standard deviation σ are increased.

  For example, the elastic roller according to the present invention has an Asker C hardness of 20-60. When the Asker C hardness is in the above range, a reduction in hardness is achieved, and a desired contact state or pressure contact state with respect to the contacted body can be maintained, which contributes to forming a high-quality image. Can do. The Asker C hardness can be a value obtained by measuring a plurality of locations on the surface of the elastic roller in accordance with JIS K6253 and arithmetically averaging the measured values. The Asker C hardness of the foamed elastic layer can be adjusted by, for example, the blending amount of the foaming agent contained in the foamed silicone rubber composition described later, the curing conditions of the foamed silicone rubber composition, and the like. For example, if the blending amount of the foaming agent is increased or the curing conditions are strict, the Asker C hardness is usually reduced.

  The elastic roller according to the present invention has a high change rate of Asker C hardness before and after the following durability test (hereinafter sometimes referred to as hardness change rate) of 90% or more, preferably 95% or more. It has durability. When the following hardness change rate is within the above range, the foamed elastic layer exhibits high durability and contributes to the formation of a high-quality image even if it is mounted on the fixing device or the image forming device for a long period of time. be able to.

  Before carrying out the following durability test, the Asker C hardness at the axial center portion and both end portions of the elastic roller according to the present invention is measured in advance in accordance with the above method. The hardness change rate can be calculated by mounting the elastic roller according to the present invention in which the Asker C hardness is measured to the durability tester shown in FIG. The durability test apparatus 70 shown in FIG. 4 is fixed to the lower surface inside the housing, and includes a heating roller 71 having an internal heater 72, and heat insulation provided on both sides along the axial direction of the heating roller 71. A test roller mounting portion 74 provided on the upper surface inside the housing so as to be movable up and down so as to face the material 73 and the heating roller 71, and a pressing force adjusting means 75 capable of moving the test roller mounting portion 74 up and down. For example, a pressure adjusting micrometer is provided. As the heating roller 71, a metal (stainless steel (SUS304)) roller having a diameter of 20 mm is mounted.

  The elastic roller according to the present invention is mounted as an elastic roller 76 on the bearing of the test roller mounting portion 74, and as shown in FIG. 4, the pressing force adjusting means 75 is operated so that the mounted elastic roller 76 is heated. The elastic roller 76 is fixed so that the elastic layer of the elastic roller 76 is recessed by 4 mm in the pressure contact portion between the heating roller 71 and the elastic roller 76 (that is, the radius of the elastic roller 76 and the heating roller). The distance d between the central axis of the elastic roller 76 and the central axis of the heating roller 71 is adjusted so as to be 4 mm shorter than the sum of the radii with 71).

  Next, the heat insulating material 73 and the internal heater 72 are activated, and the surface temperature of the heating roller 71 is adjusted to 180 ° C. Thereafter, the driving means (not shown) provided in the test roller mounting portion 74 is continuously operated at a rotational speed of 130 rpm for 100 hours. After the elastic layer 76 is released from the recessed state of the elastic layer, the elastic roller 76 is kept at room temperature for 24 hours. Let it stand for a while to finish the durability test.

  After the endurance test, the Asker C hardness at the central portion and both end portions in the axial direction of the elastic roller according to the present invention is measured according to the above method. Next, from the Asker C hardness measurement result before and after the durability test in the same part of the elastic roller according to the present invention, according to the formula: (Asker C hardness after the durability test / Asker C hardness before the durability test) × 100 (%) The partial hardness change rate at each measurement position is obtained, and the maximum partial hardness change rate is set as the hardness change rate of the elastic roller according to the present invention.

  An elastic roller 1A as an embodiment of the elastic roller according to the present invention includes, for example, a shaft body 2 and a foamed elastic layer 3 formed on the outer peripheral surface of the shaft body 2, as shown in FIG. Become.

  Since the elastic roller 1 includes the foamed elastic layer 3 in which cells having an average cell diameter of 200 to 400 μm and a standard deviation of a cell diameter of 150 to 250 μm are formed, as described above, high durability is exhibited. To do. As described above, this cell preferably has an average cell diameter of 230 to 380 μm, particularly preferably 250 to 350 μm, preferably 170 to 230 μm, particularly preferably 180 to 210 μm. is doing.

  The shaft body 2 only needs to have good conductive properties, and is usually a so-called “core metal” composed of iron, aluminum, stainless steel, brass, or the like. The shaft body 2 may be a shaft body made conductive by plating an insulating core such as a thermoplastic resin or a thermosetting resin, and imparting conductivity to the thermoplastic resin or the thermosetting resin. The shaft body may be formed of a conductive resin containing carbon black or metal powder as an agent. The outer diameter of the shaft body 2 is adjusted to an appropriate outer diameter according to the use of the elastic roller 1A.

  The foamed elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by a foamed silicone rubber composition to be described later. The foamed elastic layer 3 is a foamed elastic layer having cells on its inside and / or outer surface (cells opened on the outer surface of the foamed elastic layer 3 are not shown in FIG. 1). When the foamed elastic layer 3 has cells, the foamed elastic layer 3 can be reduced in hardness. Here, the cell formed in the foamed elastic layer 3 refers to a hollow region generated by foaming or decomposition of a foaming agent contained in the foamed silicone rubber composition. The plurality of cells formed in the foamed elastic layer 3 are in a state where they do not contact or communicate with other cells (referred to as independent cell states), a state where they contact or communicate with other cells. A state (referred to as a connected cell state) or a state in which the independent cell state and the connected cell state coexist. The shape of the cell is not particularly limited, and the shape of the cell in the independent cell state may be substantially spherical, elliptical sphere, or indefinite, and the shape of the cell in the continuous cell state is a plurality of cells communicating with each other. It may be tubular.

  The cell formed in the foamed elastic layer 3 is preferably 200 to 400 [mu] m, and preferably 300 to 400 [mu] m, in distance to other cells existing around it (hereinafter sometimes referred to as inter-cell distance). Is particularly preferred. When the inter-cell distance is within the above range, the cells can be formed more uniformly in the foamed elastic layer 3 and the hardness of the foamed elastic layer 3 can be reduced, and the foamed and broken cells can be effectively broken. Can be prevented.

  The inter-cell distance is observed with an electron microscope or the like in the same manner as the average cell diameter, and in the plurality of cells existing in the observation field, the distance between the center of a specific cell and the plurality of cells existing around the cell is measured. It can be obtained as a value obtained by measuring the distance and arithmetically averaging the measured distance between centers. Note that the center of the cell can be determined by a quadrant point based on the cell outline. The inter-cell distance in the cell can be adjusted by the blending amount of the foaming agent contained in the foamed silicone rubber composition described later, the curing conditions of the foamed silicone rubber composition, and the like. For example, when a curing condition that allows the foamed silicone rubber composition to cure rapidly is selected, the distance between cells is usually reduced, and when a curing condition that allows the foamed silicone rubber composition to cure gradually is selected, the distance between cells is usually increased.

  As described above, the foamed elastic layer 3 preferably has an Asker C hardness of 20 to 60 in that it can contribute to forming a high-quality image. For example, when the elastic roller 1A is mounted as a fixing roller or a pressure roller in a fixing device for an image forming apparatus, a desired pressure contact state with the pressure roller or the fixing roller is maintained, and the pressure roller and the fixing roller The width of the nip formed by the toner can be increased, so that the developer image transferred to the recording medium can be fixed as desired, thereby contributing to the formation of a high-quality image. it can.

  The thickness of the foamed elastic layer 3 is not particularly limited, but is usually preferably adjusted to 2 to 20 mm, and particularly preferably adjusted to 3 to 12 mm.

  As shown in FIG. 2, an elastic roller 1 </ b> B as another embodiment of the elastic roller according to the present invention includes a shaft body 2, a foamed elastic layer 3 formed on the outer peripheral surface thereof, and a foamed elastic layer 3. And a tube layer 4 formed on the outer peripheral surface.

  The shaft body 2 of the elastic roller 1B is basically the same as the shaft body 2 of the elastic roller 1A. The foamed elastic layer 3 of the elastic roller 1B is basically formed in the same manner as the foamed elastic layer 3 of the elastic roller 1A. That is, the foamed elastic layer 3 of the elastic roller 1B has cells having an average cell diameter of 200 to 400 μm and a standard deviation of the cell diameter of 150 to 250, and preferably has a cell-to-cell distance of 200 to 400 μm. The Asker C hardness is 20-60.

  The tube layer 4 is formed on the outer peripheral surface of the foamed elastic layer 3 with a material to be described later. If the tube layer 4 is formed on the outer surface of the foamed elastic layer 3, the releasability of the developer can be improved. The tube layer 4 is formed to a thickness of 1 to 100 μm, for example.

  The method for producing an elastic roller according to the present invention will be described by taking the elastic rollers 1A and 1B (hereinafter sometimes referred to as the elastic roller 1) as an example. The elastic roller 1 can be manufactured, for example, by disposing a foamed silicone rubber composition forming the foamed elastic layer 3 on the outer peripheral surface of the shaft body 2 and foaming and curing the foamed silicone rubber composition. In order to form cells having an average cell diameter in the above range and a standard deviation σ thereof in the foamed elastic layer 3, in addition to the above means, for example, among the components contained in the foamed silicone rubber composition, a silicone rubber component In addition, a method of adjusting the content of water contained in the filler (hereinafter sometimes referred to as water content) by heat treatment and decompression treatment is effective. That is, the elastic roller 1 heats and / or depressurizes the silicone rubber component and the filler, and the water content in the silicone rubber component and the filler is 0 with respect to the total mass of the silicone rubber component and the filler. A rubber composition in a range of 0.05% by mass or less is prepared, and a foaming agent or the like is added to the rubber composition to prepare a foamed silicone rubber composition. It can be manufactured by placing on the outer peripheral surface and foam-curing the foamed silicone rubber composition.

  This manufacturing method (hereinafter sometimes referred to as a manufacturing method according to the present invention) will be specifically described. In the manufacturing method according to the present invention, first, the shaft body 2 is prepared. The shaft body 2 is made of, for example, a metal such as iron, aluminum, stainless steel, brass or an alloy thereof, a resin such as a thermoplastic resin or a thermosetting resin, and carbon black or metal powder as a conductivity-imparting agent for the resin. It is prepared in a desired shape by a known method using a material such as a conductive resin blended with a body. When the shaft body 2 is required to have conductivity, in addition to the metal and the conductive resin, the surface of the insulating core body formed of the resin or the like is plated by a regular method to thereby form the shaft body 2. Can be formed. Among the materials, a metal is preferable because it can easily impart conductivity, and free cutting steel, aluminum, or stainless steel is particularly preferable.

  The shaft body 2 may be coated with a primer layer on its outer peripheral surface as desired. The primer is not particularly limited. For example, alkyd resin, phenol-modified silicone modified alkyd resin, oil-free alkyd resin, acrylic resin, silicone resin, epoxy resin, fluororesin, phenol resin, polyamide resin, Examples thereof include urethane resins and mixtures thereof. The primer layer is formed with a thickness of 0.1 to 10 μm, for example.

  Next, a foamed silicone rubber composition for forming the foamed elastic layer 3 is prepared. This foamed silicone rubber composition contains a rubber composition comprising a silicone rubber component, a filler, and 0.05% by mass or less of water.

  The silicone rubber component contained in the rubber composition is not particularly limited as long as it is a silicone rubber or a silicone-modified rubber, but a silicone rubber containing a vinyl group in its molecule (referred to as vinyl group-containing silicone raw rubber). Preferably).

As a filler contained in the rubber composition, a silica-based filler and the like are preferably exemplified. Examples of the silica-based filler include fumed silica or precipitated silica, and a surface-treated silica-based filler that has been surface-treated with a silane coupling agent represented by a general formula RSi (OR ′) ₃ is suitable. It is mentioned in. Here, R in the general formula is a glycidyl group, vinyl group, aminopropyl group, methacryloxy group, N-phenylaminopropyl group, mercapto group or the like, and R ′ is a methyl group or an ethyl group. Examples of the silane coupling agent represented by the general formula include trade names “KBM1003” and “KBE402” manufactured by Shin-Etsu Chemical Co., Ltd. The compounding quantity of a silica type filler is 5-100 mass parts with respect to 100 mass parts of said silicone rubber components, for example. A silica type filler can be used individually by 1 type or in mixture of 2 or more types.

  The water contained in the rubber composition is usually water contained or adsorbed in the silicone rubber component and / or filler, and the content is the total mass of the silicone rubber component and the filler. Is adjusted within a range of 0.050 mass% or less. Therefore, water can be added to the silicone rubber component and the filler so as to achieve the content. In this rubber composition, when the moisture content contained in the silicone rubber component and the filler is within the above range, the cell diameter of the cell formed at the time of curing the foamed silicone rubber composition containing the rubber composition is determined. In addition to being uniform, a cell having an average cell diameter of 200 to 400 μm and a standard deviation σ of a cell diameter of 150 to 250 μm can be easily formed. The water content is preferably 0.040% by mass or less, and particularly preferably 0.025% by mass or less, in that the cell diameter can be made even more highly uniform. In this invention, the water may not be contained in the rubber composition, that is, the lower limit value of the water content may be 0% by mass, but generally the water content is 0% by mass. Never become. Therefore, the content of water is usually more than 0% by mass, and practically, for example, 0.005% by mass or more in consideration of workability when adjusting the water content. preferable. In the production method according to the present invention, the content of water contained in the silicone rubber component and the filler is adjusted within the above range, but when the water content of the prepared foamed silicone rubber is within the above range, It is not necessary to adjust the water content. The water content in the rubber composition can be measured by the Karl Fischer titration method.

  The water content of the silicone rubber component and the filler can be effectively adjusted within the above range by performing at least one of a heat treatment and a decompression treatment. Since the rubber composition does not contain, for example, a crosslinking agent such as an addition reaction crosslinking agent, an addition reaction catalyst, and a reaction control agent, the silicone rubber component is not crosslinked even when subjected to heat treatment and reduced pressure treatment. The heating conditions and the decompression conditions are not restricted.

  Examples of the conditions for the heat treatment include, but are not limited to, a normal temperature and a heating temperature of 100 ° C. or more and a heating time of 1 hour or more. That is, the heat treatment may be performed under the condition that the content of water contained in the silicone rubber component and the filler is within the above range. For example, the heat treatment is performed while sampling during the heat treatment and monitoring the content of water. Can also be implemented.

  Examples of the conditions for the decompression treatment include, but are not limited to, a room temperature, a pressure of 10 hPa or less, and a decompression time of 2 hours or more. That is, the decompression process may be performed under the condition that the content of water contained in the silicone rubber component and the filler is within the above range. For example, the decompression process is performed while monitoring the content of water by sampling during the decompression process. Can also be implemented.

  In this production method, the heat treatment and the decompression treatment may be performed as long as the content of water contained in the silicone rubber component and the filler can be adjusted within the above range. Both may be implemented. Further, the heat treatment and the pressure reduction treatment may be performed simultaneously, for example, at a pressure of 10 hPa or less.

  In this way, a rubber composition having a water content within the above range can be prepared.

  The rubber composition can also be prepared by mixing the silicone rubber component and the filler and then adjusting the water content within the above range. Examples of rubber compositions containing vinyl group-containing silicone rubber as a silicone rubber component, fillers, and additives other than crosslinking agents include trade names “KE Series” and “KEG Series” manufactured by Shin-Etsu Chemical Co., Ltd. Can be easily obtained.

  The foamed silicone rubber composition forming the foamed elastic layer 3 contains, in addition to the rubber composition, a foaming agent, a crosslinking agent, and various additives as required.

  The foaming agent may be any foaming agent conventionally used for foamed rubber. Examples of the inorganic foaming agent include sodium bicarbonate and ammonium carbonate. Examples of the organic foaming agent include diazoamino derivatives, azonitrile derivatives, and azodicarboxylic acids. And organic azo compounds such as acid derivatives. Usually, an inorganic foaming agent is used when forming a continuous cell in rubber, and an organic foaming agent is used when forming an independent cell. In the elastic roller 1, the foaming agent is preferably an organic foaming agent in that it can form a cell in an independent cell state. Specifically, for example, azodicarboxylic acid amide, azobis-isobutyrate is used. An azo compound such as ronitrile is preferably used. In particular, dimethyl-1,1'-azobis (1-cyclohexanecarboxylate) can be preferably used. The blending amount of the foaming agent is appropriately adjusted according to the average cell diameter of the cells formed in the foamed elastic layer 3 and its standard deviation σ. A foaming agent can be used individually by 1 type or in mixture of 2 or more types.

  The crosslinking agent may be any one that crosslinks the silicone rubber component, and examples thereof include an addition reaction crosslinking agent, an addition reaction catalyst, and a reaction control agent. Examples of the various additives include colorants, flame retardant improvers, thermal conductivity improvers, mold release agents, dispersants, pulverized quartz, and non-reinforcing silica. These various additives are blended in a desired blending amount.

  As such a foamed silicone rubber composition, an addition reaction type foamed silicone rubber composition is particularly preferred. The addition reaction type foamed silicone rubber composition contains a vinyl group-containing silicone raw rubber, a silica-based filler, water, the foaming agent, an addition reaction crosslinking agent, an addition reaction catalyst, and a reaction control agent. If desired, an organic peroxide crosslinking agent, a heat resistance improver, and various additives may be further contained. In this addition reaction type foamed silicone rubber composition, the vinyl group-containing silicone raw rubber and the silica-based filler are the silicone rubber component and filler in the rubber composition. That is, the foamed silicone rubber composition contains the rubber composition, the foaming agent, an addition reaction crosslinking agent, an addition reaction catalyst, and a reaction control agent, and if desired, further an organic peroxide crosslinking agent. And a heat resistance improver and various additives.

  The vinyl group-containing silicone raw rubber may be a silicone raw rubber containing a vinyl group in the molecule, and examples thereof include millable silicone rubber and heat-crosslinked silicone rubber (HTV: High Temperature Vulcanizing). The vinyl group-containing silicone raw rubber can be used alone or in combination of two or more.

  The silica-based filler contained in the addition reaction type foamed silicone rubber composition is basically the same as the silica-based filler exemplified as the filler contained in the rubber composition, and the content thereof is also basic. The same.

  Suitable examples of the addition reaction crosslinking agent include known organohydrogenpolysiloxanes as addition reaction type crosslinking agents having two or more SiH groups (SiH bonds) in one molecule. The addition amount of the addition reaction crosslinking agent is preferably 0.01 to 20 parts by mass with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber. An addition reaction crosslinking agent can be used individually by 1 type or in mixture of 2 or more types.

  The addition reaction catalyst may be any catalyst that is usually used in addition reactions of silicone raw rubber, and examples thereof include simple metals of Group 9 or 10 of the periodic table and compounds thereof. The addition amount of the addition reaction catalyst is sufficient as the catalyst amount, and is usually 1 to 1 with respect to the addition reaction type foamed silicone rubber composition in terms of the metal amount of Group 9 or Group 10 of the periodic table. 000 ppm. An addition reaction catalyst can be used individually by 1 type or in mixture of 2 or more types.

  As the reaction control agent, a known reaction control agent can be used without particular limitation, and examples thereof include methylvinylcyclotetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, and hydroperoxide. In order to form cells having an average cell diameter in the above range and a standard deviation σ thereof in the foamed elastic layer 3, the reaction control agent is used in an amount of 0.25 to 0.8 with respect to 100 parts by mass of the foamed silicone rubber composition. It is preferable that it is a mass part, and it is especially preferable that it is 0.3-0.7 mass part. The reaction control agents can be used alone or in combination of two or more.

  As the conductivity imparting agent, the conductivity imparting agent can be used without any particular limitation. The compounding amount of the conductivity-imparting agent may be an amount that can adjust the conductivity of the foamed elastic layer 3 to a desired range. For example, it is 2 to 80 parts by mass with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber. There should be. The conductivity-imparting agent can be used alone or in combination of two or more.

  The organic peroxide cross-linking agent can be used alone to cross-link vinyl group-containing silicone raw rubber, but if used in combination as an auxiliary cross-linking agent for an addition reaction cross-linking agent, the physical properties of the silicone rubber, such as strength and strain, can be improved. improves. Examples of the organic peroxide crosslinking agent include benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, and 2,5-dimethyl-2,5-bis. (T-butylperoxy) hexane and the like. The compounding amount of the organic peroxide crosslinking agent is preferably 0.3 to 10 parts by mass with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber. An organic peroxide crosslinking agent can be used individually by 1 type or in mixture of 2 or more types.

  Examples of silicone rubber compositions containing the vinyl group-containing silicone raw rubber, the silica-based filler, and the various additives other than the crosslinking agent include trade names “KE series” and “KEG” manufactured by Shin-Etsu Chemical Co., Ltd. Series "etc. can be easily obtained.

  The foamed silicone rubber composition is prepared by mixing the rubber composition, a foaming agent, a crosslinking agent, and various additives as required. For example, the addition reaction type foamed silicone rubber composition includes the rubber composition, a foaming agent, an addition reaction crosslinking agent, an addition reaction catalyst, a reaction control agent, and optionally an organic peroxide crosslinking agent and / or heat resistance. It is prepared by mixing a property improver and, if desired, various additives. In addition, components other than the rubber composition usually have a small water content and can be almost ignored.

  The foamed silicone rubber composition thus prepared is placed on the outer peripheral surface of the shaft body 2 and foamed and cured to form the foamed elastic layer 3. For example, the foamed elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by performing molding and heat curing simultaneously or continuously by a known molding method. The method for molding the foamed silicone rubber composition may be any method that allows the foamed silicone rubber composition to be disposed on the outer peripheral surface of the shaft body 2, for example, continuous vulcanization by extrusion, pressing, molding by injection, etc. There is no particular limitation. For example, when the foamed silicone rubber composition is an addition reaction type foamed silicone rubber composition described later, extrusion molding or the like can be selected as the molding method.

  The curing condition of the foamed silicone rubber composition is that the foamed silicone rubber composition disposed on the outer peripheral surface of the shaft body 2 is cured, and when it contains a foaming agent, the foaming agent is sufficiently cured to decompose or foam. It is sufficient that the conditions are satisfied, and the conditions are appropriately adjusted according to the composition of the foamed silicone rubber composition, the type of foaming agent, and the like. For example, when the foamed silicone rubber composition is an addition reaction type foamed silicone rubber composition to be described later, the curing conditions are usually 100 to 400 ° C., particularly a heating temperature of 200 to 400 ° C., several minutes to 1 hour or less. In particular, a heating time of 5 minutes or more and 30 minutes or less is preferable in that an independent cell having an average cell diameter and standard deviation within the above range can be formed.

  If necessary, the foamed silicone rubber composition can be secondarily heated. In the secondary heating, for example, the foamed silicone rubber composition crosslinked under the above-described conditions is further extruded, for example, at 180 to 250 ° C, preferably 190 to 230 ° C, and 1 to 24. Over a period of time, preferably 3 to 10 hours, or using a mold, for example, 130 to 200 ° C., preferably 150 to 180 ° C., for 5 minutes to 24 hours, preferably 10 minutes to 10 hours, This is done by heating again.

  Thus, when forming the foaming elastic layer 3, it is preferable to adjust to the foaming rate of 150 to 480%, and it is especially preferable to adjust to the foaming rate of 200 to 450%. When the foaming and curing is performed so that the expansion ratio falls within the above range, the hardness of the foamed elastic layer 3 can be reduced to a desired hardness and the initial cell formation state can be maintained over a long period of time. The expansion ratio of the foamed elastic layer 3 can be calculated from the volume and mass of the foamed elastic layer 3 measured by a conventional method. The foaming rate of the foamed elastic layer 3 can be adjusted by the blending amount of the foaming agent contained in the foamed silicone rubber composition, the curing conditions of the foamed silicone rubber composition, and the like. For example, when the blending amount of the foaming agent is increased or the curing conditions are strict, the foaming rate is usually increased.

  The foamed elastic layer 3 is subjected to a grinding step, a polishing step and / or a cutting step, etc., which are adjusted to a desired size and shape, if desired. The grinding process, the polishing process, and / or the cutting process can be performed according to a conventional method using a conventionally used grinder, cylindrical grinder, file, or the like.

  In the manufacturing method according to the present invention, the tube layer 4 is formed on the outer peripheral surface of the foamed elastic layer 3 formed in this manner as desired. The tube layer 4 is formed on the outer surface of the foamed elastic layer 3 by inserting the foamed elastic layer 3 into a tubular body that is formed in advance in a cylindrical shape having the same inner diameter as that of the foamed elastic layer 3. It is preferable in that the tube layer 4 having a smooth surface can be formed without being greatly affected by the uneven shape present on the surface of the foamed elastic layer 3. Of course, the tube layer 4 may be formed by applying a material described later to the outer peripheral surface of the foamed elastic layer 3 according to, for example, a dipping method, a spraying method, etc., and then curing and / or crosslinking.

  The material for forming the tube layer 4 is not particularly limited, but the elastic roller 1B is preferably in contact with or pressed against the contacted body, and thus is preferably a material that is not easily permanently deformed. For example, alkyd resin , Alkyd resin modified products such as phenol modified / silicone modified, oil free alkyd resin, acrylic resin, silicone resin, epoxy resin, fluororesin, phenol resin, polyamide resin, urethane resin, polyamideimide resin, and mixtures thereof It is done.

  In this way, the elastic roller 1 in which the foamed elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 can be manufactured. According to this manufacturing method, a cell having a uniform cell diameter regardless of the average cell diameter in the range of 200 to 400 μm, specifically, a cell having a standard deviation of the cell diameter in the range of 150 to 250 μm. Can be formed. Therefore, according to this manufacturing method, the object of providing an elastic roller manufacturing method capable of manufacturing an elastic roller having a foamed elastic layer having excellent durability can be achieved.

  The foamed elastic layer 3 in the elastic roller 1 is formed with cells having an average cell diameter of 200 to 400 μm and a standard deviation of an average cell diameter of 150 to 250 μm. However, the rate of change in hardness is small. Therefore, according to the present invention, it is possible to achieve the object of providing an elastic roller having a foamed elastic layer having a small hardness change and excellent durability.

  Since the elastic roller 1 achieves both low hardness and high durability, an elastic roller mounted on the image forming apparatus, such as a charging roller, a developing roller, a transfer roller, a pressure roller, a paper feed and conveyance roller, It is preferably used as a fixing roller, a developer supply roller and the like, and particularly preferably used as a fixing roller, a heating roller, and a developer supply roller. When the elastic roller 1 is mounted as an elastic roller of the image forming apparatus, it can contribute to forming a high quality image over a long period of time.

  The elastic roller 1 includes a foamed elastic layer 3 having a highly uniform cell diameter. Accordingly, in the foamed elastic layer 3, like an elastic roller mounted on an image forming apparatus with a high printing speed, an image forming apparatus with a high-definition image, and / or a downsized image forming apparatus. It is particularly suitably used as an elastic roller requiring high cell uniformity.

  The elastic roller according to the present invention is not limited to the above-described embodiments, and various modifications can be made within a range in which the object of the present invention can be achieved. For example, although the foamed elastic layer 3 has a single layer structure, in this invention, the foamed elastic layer may be a foamed elastic layer in which a plurality of layers are laminated.

  In addition, the elastic roller 1 is provided with a heating element such as an electric heater or a heating coil in the shaft body 2, in the foamed elastic layer 3, and / or between the shaft body 2 and the foamed elastic layer 3, depending on the application. You may have. For example, when the elastic roller 1 is used as a fixing roller of a heat roller fixing device, a heating body is provided in the shaft body 2.

  Further, the elastic roller 1 has a foamed elastic layer 3 formed on the outer peripheral surface of the shaft body 2. In this invention, the foamed elastic layer is formed on the outer peripheral surface of the shaft body via a primer layer or an adhesive layer. It may be formed. The primer for forming the primer layer is not particularly limited, and examples thereof include a silane coupling primer. In addition, the adhesive forming the adhesive layer is not particularly limited. For example, alkyd resin, modified alkyd resin such as phenol modified / silicone modified, oil-free alkyd resin, acrylic resin, silicone resin, epoxy resin, fluorine Examples thereof include resins, phenol resins, polyamide resins, urethane resins, and mixtures thereof. Among these, an adhesive having an amino group and / or a hydroxyl group is preferable. Moreover, an isocyanate compound, a melamine compound, an epoxy compound, a peroxide, a phenol compound, a hydrogensiloxane compound, etc. are used as a crosslinking agent for curing these resins.

  Further, the elastic roller 1A has the foamed elastic layer 3 as the outermost layer, and the elastic roller 1B has the tube layer 4 as the outermost layer. In this invention, the elastic roller is placed on the outer peripheral surface of the foamed elastic layer or the tube layer. Other layers such as an elastic layer, a release layer, a coat layer, a surface layer, and / or a protective layer may be formed.

  A fixing device for an image forming apparatus (hereinafter sometimes referred to as a fixing device according to the present invention) and an image forming apparatus (hereinafter referred to as an image forming apparatus according to the present invention) provided with the elastic roller 1A according to the present invention. An example) will be described with reference to FIG.

  As shown in FIG. 3, the image forming apparatus 30 according to the present invention includes a rotatable image carrier 31 on which an electrostatic latent image is formed, for example, a photoconductor, and a periphery of the image carrier 31. A charging unit 32, for example, a charging roller, an exposure unit 33, a developing unit 40, a transfer unit 34, for example, a transfer roller and a cleaning unit 37, and a fixing unit 35, for example, a fixing device for an image forming apparatus, are provided downstream in the conveyance direction of the recording medium. . The developing means 40 is formed basically in the same manner as the conventional developing means. Specifically, as shown in FIG. 3, the developer 42 is supplied to the developer accommodating portion 41 and the image carrier 31. A developer carrier 44, a developer supply unit 43 that supplies the developer 42 to the developer carrier 44, and a developer regulating member 45 that charges the developer 42 are provided. As long as the developer 42 is a one-component developer, the developer 42 may be a dry developer or a wet developer, and may be a non-magnetic developer or a magnetic developer.

  The fixing unit 35 is only required to fix the developer 42 (electrostatic latent image) transferred to the recording body 36. For example, a heat roller fixing device having a heat generating fixing roller, an oven fixing device, etc. A heat fixing device, a pressure fixing device including a fixing roller capable of pressing, and the like can be used. These fixing devices may be fixing devices having endless belts. In FIG. 3, the fixing means 35 having an endless belt is the fixing device for an image forming apparatus according to the present invention. As shown in FIG. 3, the fixing device 35 has a fixing roller 53 and an endless belt supported in the vicinity of the fixing roller 53 in a housing 50 having an opening 52 through which the recording medium 36 passes. A roller 54, an endless belt 55 wound around the fixing roller 53 and the endless belt support roller 54, and a pressure roller 56 disposed opposite to the fixing roller 53. The pressure heat fixing device is configured to be rotatably supported so that the pressure roller 56 is in contact with or in pressure contact with each other. The endless belt support roller 54 may be a roller that is normally used in an image forming apparatus. For example, an elastic roller or the like is used. For example, the endless belt 55 may be an endless belt formed of a resin such as polyamide or polyamideimide, and the thickness of the endless belt 55 may be appropriately adjusted to match the fixing unit 35. Each of the fixing roller 53, the endless belt support roller 54, and the pressure roller 56 includes a heating body (not shown), and the pressure roller 56 causes the endless belt 55 to be moved by a biasing means (not shown) such as a spring. Via the fixing roller 53. By passing the recording medium 36 between the endless belt 55 and the pressure roller 56, the recording medium 36 is heated simultaneously with the pressurization, and the developer 42 (electrostatic latent image) transferred to the recording medium 36 is fixed. be able to.

  The image forming apparatus 30 according to the present invention includes a charging roller of the charging unit 32, a developing roller of the developing unit 40, a transfer roller of the transfer unit 34, a fixing roller of the fixing unit 35, a pressure roller or an endless belt support roller, and a cleaning unit. Various rollers such as a cleaning roller and a paper feeding / conveying roller are provided, and the elastic roller according to the present invention is used as at least one of these various rollers. Preferably, the elastic roller according to the present invention is used as at least one of a charging roller, a developing roller, a transfer roller, a fixing roller and a pressure roller, and particularly preferably according to the present invention as a fixing roller and a pressure roller. Elastic rollers are used.

  The image forming apparatus 30 according to the present invention operates as follows. First, in the image forming apparatus 30, the image carrier 31 is uniformly charged by the charging unit 32, and an electrostatic latent image is formed on the surface of the image carrier 31 by the exposure unit 33. Next, the developer 42 is supplied from the developing means 40 to the image carrier 31 to develop the electrostatic latent image. Next, the developer image is transferred onto a recording body 36 conveyed between the image carrier 31 and the transfer means 34. The recording body 36 is conveyed to the fixing unit 35, and the developer image is fixed on the recording body 36 as a permanent image. In this way, an image can be formed on the recording body 36.

  The image forming apparatus 30 according to the present invention includes at least one of various rollers such as a charging roller, a developing roller, a developer supply roller, a transfer roller, a fixing roller, a pressure roller, an endless belt support roller, a cleaning roller, and a paper feeding / conveying roller. Since the elastic roller according to the present invention is used as one roller, the fixing device 35 for the image forming apparatus and the image forming apparatus 30 can exhibit high durability.

  The image forming apparatus 30 is an electrophotographic image forming apparatus. However, in the present invention, the image forming apparatus is not limited to the electrophotographic system, and may be, for example, an electrostatic image forming apparatus. Good. Further, the image forming apparatus 30 is a monochrome image forming apparatus in which the developing unit 40 contains only a single color developer 42. However, in this invention, the image forming apparatus is not limited to a monochrome image forming apparatus. It may be an image forming apparatus. Examples of the color image forming apparatus include a four-cycle color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier to an intermediate transfer body, and a plurality of image carriers provided with developing means for each color. Examples thereof include a tandem type color image forming apparatus in which a body is arranged in series on an intermediate transfer body or a transfer conveyance belt. The image forming apparatus 30 is an image forming apparatus such as a copying machine, a facsimile machine, or a printer.

  In the image forming apparatus 30, a one-component developer is advantageously used as the developer 42, but a two-component developer including a toner and a carrier such as iron or nickel can also be used. .

Example 1
First, an electroless nickel-plated shaft (diameter 12 mm x length 350 mm, SUM22) was washed with toluene, and primer “No. 101A / B” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name) was applied. did. The primer-treated shaft was fired at 180 ° C. for 30 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer.

  Next, a rubber composition A “KE-904FU” (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., water content: 0.07% by mass) containing a vinyl group-containing silicone raw rubber and a silica-based filler, a heating temperature of 150 ° C., Heat treatment was performed under the condition of a heating time of 2 hours. It was 0.009 mass% when the moisture content of the rubber composition A after a heat processing was measured by the Karl Fischer titration method.

  100 parts by mass of the rubber composition A thus adjusted in water content, 2.0 parts by mass of an addition reaction crosslinking agent “C-153A” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name), and an organic foaming agent azobis -2.5 parts by mass of isobutyronitrile "KEP-13" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), an appropriate amount of platinum catalyst as an addition reaction catalyst, and a reaction control agent "R-153A" (Shin-Etsu Chemical) Product name: 0.5 parts by mass, organic peroxide crosslinking agent “C-3” (manufactured by Shin-Etsu Chemical Co., Ltd .: product name), and heat resistance improver “KEP-12” (Shin-Etsu) Chemical Industry Co., Ltd. product name) 1.0 part by mass was sufficiently kneaded with two rolls in an environment of about 50% humidity to prepare an addition reaction type foamed silicone rubber composition A.

  Next, the shaft body 2 on which the primer layer is formed and the addition reaction type foamed silicone rubber composition A are integrally dispensed by an extrusion molding machine, and then the addition reaction type foaming is performed using an infrared heating furnace (IR furnace). The silicone rubber composition A was heated at 250 ° C. for 10 minutes to foam-crosslink the addition reaction type foamed silicone rubber composition A. Then, the addition reaction type | mold foaming silicone rubber composition A after foaming bridge | crosslinking was further heated for 7 hours at 200 degreeC using the gear oven, and was left to stand at normal temperature for 1 hour. Next, the rubber cured body thus formed was adjusted to an outer diameter of 29 mm with a cylindrical grinder to produce an elastic roller.

(Example 2)
An elastic roller was produced in the same manner as in Example 1 except that the heating time of the rubber composition A was changed to 1 hour.
Example 3
An elastic roller was produced in the same manner as in Example 1 except that the heating time of the rubber composition A was changed to 0.16 hours.

Example 4
An elastic roller was produced in the same manner as in Example 1 except that the reaction control agent was changed to 0.7 parts by mass.
(Example 5)
An elastic roller was produced in the same manner as in Example 1 except that the reaction control agent was changed to 0.3 parts by mass.

(Example 6)
An elastic roller was produced in the same manner as in Example 1 except that the heating time of the rubber composition A was changed to 3 hours.
(Example 7)
An elastic roller was produced in the same manner as in Example 1 except that the heating time of the rubber composition A was changed to 0.1 hour.

(Example 8)
Instead of the heat treatment of the rubber composition A, the rubber composition “KE-904FU” was subjected to a pressure reduction treatment under conditions of a pressure of 10 hPa and a pressure reduction time of 4 hours, and the water content of the rubber composition B (Karl Fischer titration method) ) Was adjusted to 0.029% by mass. Using 100 parts by mass of the rubber composition B with the water content adjusted in this manner, the addition reaction type foamed silicone rubber composition B was prepared in the same manner as in Example 1 to produce an elastic roller.
Example 9
After the heat treatment of the rubber composition A in Example 1, the vacuum treatment of Example 8 was performed to adjust the water content of the rubber composition C (measured value by Karl Fischer titration method) to 0.005% by mass. Using 100 parts by mass of the rubber composition C with the water content adjusted in this manner, the addition reaction type foamed silicone rubber composition C was prepared in the same manner as in Example 1 to produce an elastic roller.

(Comparative Example 1)
An elastic roller was produced in the same manner as in Example 1 except that the reaction control agent was changed to 0.2 parts by mass.
(Comparative Example 2)
An elastic roller was produced in the same manner as in Example 1 except that the reaction control agent was changed to 0.9 parts by mass.

(Comparative Example 3)
An elastic roller was produced in the same manner as in Example 1 except that the reaction control agent was changed to 0.1 parts by mass and the IR furnace overheating was changed to 300 ° C. for 5 minutes.
(Comparative Example 4)
An elastic roller was produced in the same manner as in Example 8, except that the decompression time of the rubber composition was changed to 0.16 hours.

(Comparative Example 5)
An elastic roller was produced in the same manner as in Example 1 except that the reaction control agent was changed to 0.1 parts by mass.
(Comparative Example 6)
An elastic roller was produced in the same manner as in Example 1 except that the heat treatment was changed to a treatment for 2 hours in a high-humidity tank at 30 ° C. and 80% humidity.

(Comparative Example 7)
An elastic roller was produced in the same manner as in Example 1 except that the heat treatment of the rubber composition “KE-904FU” was not performed.
(Comparative Example 8)
An elastic roller was produced in the same manner as in Example 8 except that the rubber composition “KE-904FU” was not subjected to the decompression treatment.

(Comparative Example 9)
An elastic roller was manufactured in the same manner as in Example 1 except that the heat treatment was changed to a treatment for 24 hours in a high-humidity tank in an atmosphere of 30 ° C. and 80% humidity.
(Comparative Example 10)
Instead of the addition reaction type foamed silicone rubber composition A, 100 parts by mass of conductive silicone rubber (trade name “XE23-A4707” manufactured by Toshiba Silicone Co., Ltd.) and t-butylperoxy-2-ethylhexanoate 0 0.5 part by mass, 1.0 part by mass of 2,5-dimethyl-2,5-di-t-butylperoxyhexane, azodicarbonamide-based foaming agent (trade name “Celmic CAP, manufactured by Sankyo Kasei Co., Ltd.” An elastic roller was produced in the same manner as in Example 1 except that a foamed rubber composition containing 3 parts by mass of -500 "was used.

  The water content of each rubber composition in Examples 2 to 9 and Comparative Examples 1 to 10 was measured by the Karl Fischer titration method, and the results are shown in Table 1. In addition, each addition reaction type foaming silicone rubber composition in Examples 1-8 and Comparative Examples 1-3, 5 and 6 has substantially the same water content as the rubber composition after the heat treatment, and the addition reaction of Example 9 The type foamed silicone rubber composition C has substantially the same water content as the rubber composition C after heat treatment and reduced pressure treatment, and the addition reaction type foamed silicone rubber composition of Comparative Example 4 is the same as the rubber composition after reduced pressure treatment. The water content was almost the same. Further, the addition reaction type foamed silicone rubber compositions of Comparative Examples 7 and 8 had the same water content as that of the rubber composition.

  The average cell diameter, the standard deviation σ, and the inter-cell distance of the cells opened in the cut surface obtained by cutting the substantially central portion in the foamed elastic layer of the elastic roller thus produced by a plane perpendicular to the axial direction And the foaming rate of the foamed elastic layer was calculated. The results are shown in Table 1.

  Each elastic roller manufactured in this way was mounted on a durability tester shown in FIG. 4, and a durability test was performed according to the above conditions and methods.

  The durability of each elastic roller is “◎ when the foamed elastic layer 3 in each elastic roller is visually and observed with a camera and no cell damage, cracks, destruction, etc. of the foamed elastic layer 3 can be confirmed. "A" indicates that the cells of the foamed elastic layer 3 were slightly damaged, cracked, broken, etc., but there were no practical problems. The case where damage, cracks, and destruction were observed was evaluated as “x”, and the case where continuous operation was not possible under the above conditions was evaluated as “xx”, and was evaluated in four stages. The results are shown in Table 1.

  Further, the hardness change rate of each elastic roller calculated according to the above method is “◎” when the hardness change rate is 95% or more, “◯” when 90% or more and less than 95%, and less than 90%. The case where there was "x" was evaluated in three steps. The results are shown in Table 1.

  When the evaluation of the durability and the rate of change in hardness is “◎” and “○”, high quality is obtained when the elastic roller is mounted as a fixing roller and / or a developer supply roller on the fixing device of the image forming apparatus. It is speculated that an image can be formed over a fairly long period of time. On the other hand, when the durability evaluation is “x”, a high-quality image is formed over a long period of time when the elastic roller is attached to the fixing device of the image forming apparatus as a fixing roller and / or a developer supply roller. If the elastic roller is attached to the fixing device of the image forming apparatus as a fixing roller and / or a developer supply roller, a high-quality image is formed. I guess it can't be done.

1, 1A, 1B, 76 Elastic roller 2 Shaft body 3 Foamed elastic layer 4 Tube layer 30 Image forming apparatus 31 Image carrier 32 Charging means 33 Exposure means 34 Transfer means 35 Fixing means 36 Transfer object 37 Cleaning means 40 Developing means 41 Developer container 42 Developer 43 Developer supply means 44 Developer carrier 45 Developer regulating member 50 Housing 52 Opening 53 Fixing roller 54 Endless belt support roller 55 Endless belt 56 Pressure roller 70 Durability test device 71 Heating roller 72 Internal heater 73 Insulating material 74 Test roller mounting portion 75 Pressure adjusting means

Claims (4)

An elastic roller having a silicone foam elastic layer on the outer peripheral surface of the shaft body,
The silicone foamed elastic layer has an elastic cell having cells having an average cell diameter of 200 to 400 μm and a standard deviation of the cell diameter of 150 to 250 μm.   The silicone foam elastic layer is obtained by heating and curing a foamed silicone rubber composition containing a rubber composition comprising a silicone rubber component, a filler, and water of 0.050% by mass or less on the outer peripheral surface of the shaft body. The elastic roller according to claim 1, wherein   A fixing device for an image forming apparatus, comprising the elastic roller according to claim 1.   An image forming apparatus comprising the elastic roller according to claim 1.

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