Elastic roller

Abstract

To provide an elastic roller capable of obtaining a high-quality image.SOLUTION: The elastic roller of the present invention is an elastic roller comprising a shaft 2 and an elastic layer 3 on the outer periphery of the shaft 2, wherein the elastic layer 3 is formed by extrusion molding, vulcanizing, and polishing, and wherein the difference between the roughness Rz of the elastic roller after vulcanizing and polishing until the outer diameter of the elastic roller becomes the product outer diameter + 1. 2mm and the roughness Rz of the elastic roller after vulcanizing and further polishing until the outer diameter of the elastic roller becomes the product outer diameter is within ± 0.5 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an elastic roller. [Background technology]

[0002] Various image forming devices using electrophotography are employed in printers such as laser printers and video printers, copiers, facsimiles, and multifunction machines thereof. Electrophotographic image forming devices include various elastic rollers, such as developing rollers, transfer rollers, toner supply rollers, and cleaning rollers, each having an elastic layer provided on the outer periphery of a shaft. The elastic layer can be formed by coating the outer periphery of the shaft with a rubber composition using, for example, a crosshead extrusion molding machine, followed by vulcanization (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-224378 Summary of the Invention [Problem to be solved by the invention]

[0004] After vulcanization, the elastic layer is polished to a desired outer diameter. To minimize the effects of pressure and heat during polishing, it is preferable to polish the layer to a small amount. However, if the polishing amount is small, the surface of the polished elastic layer may be uneven. When such an elastic roller is used in an electrophotographic image forming apparatus, there is a concern that image quality may be reduced. The present invention has been made in view of the above circumstances, and has as its object to provide an elastic roller that can obtain high-quality images. [Means for solving the problem]

[0005] As a result of extensive research, the inventors discovered that the non-uniformity of the surface of the elastic layer is due to the hardness deviation in the thickness direction of the elastic layer. They also discovered that the hardness deviation can be improved by selecting the right type of vulcanizing agent and combining them, and that by doing so, an elastic layer with a uniform surface can be formed even with a small amount of polishing, which led to the present invention.

[0006] The present invention is an elastic roller comprising a shaft body and an elastic layer on the outer periphery of the shaft body, the elastic layer being formed by extrusion molding, vulcanization, and polishing, and the difference between the surface roughness Rz when the outer diameter of the elastic roller is polished after vulcanization until it is the product outer diameter + 1.2 mm and the surface roughness Rz when it is further polished to the product outer diameter is within ±0.5 μm.

[0007] The elastic layer is preferably made of silicone rubber.

[0008] The thickness of the elastic layer is preferably 2 mm or more. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an elastic roller that can obtain high-quality images. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view showing an embodiment of an elastic roller of the present invention. [Figure 2] 1 is a graph showing the relationship between the outer diameter and the surface roughness Rz of the elastic roller raw body in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Elastic roller] As shown in FIG. 1, the elastic roller 1 of the present invention is an elastic roller that includes a shaft 2 and an elastic layer 3 on the outer periphery of the shaft 2. Each component will be described in detail below.

[0012] (shaft body) The shaft 2 can preferably be a shaft having conductive properties and used in a conventionally known elastic roller. The shaft 2 is preferably made of at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass. Such a shaft 2 is also generally known as a "core metal."

[0013] The shaft 2 may contain an insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. The shaft 2 may include, for example, a core made of an insulating resin and a plating layer provided on the core. Such a shaft 2 can be obtained, for example, by plating the core made of an insulating resin to make it conductive. The shaft 2 is preferably a cored bar in order to obtain good electrical conductivity.

[0014] The shape of the shaft 2 is preferably, for example, rod-like or tubular. The cross-sectional shape of the shaft 2 may be, for example, circular or elliptical, or may be non-circular such as polygonal. The outer peripheral surface of the shaft 2 may be subjected to treatment such as cleaning, degreasing, or primer treatment.

[0015] The axial length of the shaft 2 is not particularly limited and may be adjusted appropriately depending on the type of the image forming apparatus in which it is installed. The diameter of the shaft 2 (diameter of the circumscribing circle) is also not particularly limited and may be adjusted appropriately depending on the type of the image forming apparatus in which it is installed.

[0016] (elastic layer) The elastic layer 3 is preferably made of silicone rubber. For example, the following resin composition for the elastic layer is extruded onto the outer peripheral surface of the shaft 2, followed by vulcanization and polishing. The resin composition for the elastic layer contains at least (a) organopolysiloxane, (b) a conductivity imparting agent, (c) a filler, and (d) a vulcanizing agent.

[0017] (a) Organopolysiloxane The organopolysiloxane is preferably an organopolysiloxane having a degree of polymerization of 100 or more and represented by the following average composition formula (I). R 1 a SiO (4-a) / 2 (I) (In the formula, R 1 represent the same or different unsubstituted or substituted monovalent hydrocarbon groups, and a is a positive number of 1.95 or more and 2.05 or less.

[0018] R 1 Examples of the alkyl group include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl groups, cycloalkyl groups such as cyclohexyl groups, alkenyl groups such as vinyl, allyl, butenyl, and hexenyl groups, aryl groups such as phenyl and tolyl groups, and aralkyl groups such as β-phenylpropyl groups. 1 may be groups in which some or all of the hydrogen atoms of these hydrocarbon groups have been substituted with a substituent. The substituent may be, for example, a halogen atom, a cyano group, etc. Examples of hydrocarbon groups having a substituent include a chloromethyl group, a trifluoropropyl group, and a cyanoethyl group.

[0019] The molecular chain terminals of the organopolysiloxane are preferably blocked with a trialkylsilyl group such as a trimethylsilyl group, a dialkylaralkylsilyl group such as a dimethylvinylsilyl group, a dialkylhydroxysilyl group such as a dimethylhydroxysilyl group, or a trialalkylsilyl group such as a trivinylsilyl group.

[0020] The organopolysiloxane preferably has two or more alkenyl groups in the molecule. 1 Of these, it is preferable that the alkenyl group account for 0.001 mol % or more and 5 mol % or less (more preferably 0.01 mol % or more and 0.5 mol % or less).Vinyl groups are particularly preferable as the alkenyl groups contained in the organopolysiloxane.

[0021] Organopolysiloxanes can be obtained, for example, by co-hydrolysis and condensation of one or more organohalosilanes, or by ring-opening polymerization of cyclic polysiloxanes such as siloxane trimers or tetramers. The organopolysiloxane may basically be a linear diorganopolysiloxane, or may be partially branched. Furthermore, the organopolysiloxane may be a mixture of two or more organopolysiloxanes with different molecular structures.

[0022] The organopolysiloxane preferably has a kinematic viscosity of 100 cSt or more, more preferably 100,000 cSt or more and 10,000,000 cSt or less at 25° C. The degree of polymerization of the organopolysiloxane is preferably, for example, 100 or more, more preferably 3,000 or more and 10,000 or less.

[0023] (b) Conductive agent Examples of the conductivity imparting agent include conductive powders containing conductive carbon, rubber carbons, metals, conductive polymers, etc. Carbon black is preferably used as the conductive powder, and examples of carbon black include furnace black such as Ketjenblack (registered trademark), acetylene black, channel black, and thermal black. The resistance value of the elastic layer is preferably adjusted to the range of 4 to 9 (log Ω).

[0024] (c) Filler Examples of the filler include silica-based fillers, such as fumed silica and precipitated silica.

[0025] Silica-based fillers include R 2 Si(OR 3 A surface-treated silica-based filler that has been surface-treated with a silane coupling agent represented by formula (R) 3 can be preferably used. 2may be a group having a vinyl group or an amino group, such as a glycidyl group, a vinyl group, an aminopropyl group, a methacryloxy group, an N-phenylaminopropyl group, or a mercapto group. 3 may be an alkyl group, such as a methyl group or an ethyl group. Silane coupling agents are readily available, for example, under the trade names "KBM1003" and "KBE402" manufactured by Shin-Etsu Chemical Co., Ltd. The surface-treated silica-based filler can be obtained by treating the surface of a silica-based filler with a silane coupling agent according to a standard method. Commercially available surface-treated silica-based fillers may be used, such as "Zeothix 95" manufactured by JMHUBER Corporation.

[0026] The amount of silica-based filler blended is preferably 11 parts by mass or more and 39 parts by mass or less, and more preferably 15 parts by mass or more and 35 parts by mass or less, per 100 parts by mass of (a) organopolysiloxane. The average particle size of the silica-based filler is preferably 1 μm or more and 80 μm or less, and more preferably 2 μm or more and 40 μm or less. The average particle size of the silica-based filler can be measured as the median size using a particle size distribution measuring device based on the laser diffraction method.

[0027] (d) Vulcanizing agent Examples of the vulcanizing agent include an addition vulcanizing agent and an organic peroxide vulcanizing agent. Suitable examples of the addition vulcanizing agent include organohydrogenpolysiloxanes, which are known as addition reaction type vulcanizing agents having two or more SiH groups (SiH bonds) in one molecule. The addition vulcanizing agents can be used alone or in combination of two or more. The amount of the addition vulcanizing agent is usually preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the resin composition for the elastic layer.

[0028] When an addition vulcanizing agent is used, the organic peroxide vulcanizing agent can crosslink the millable silicone rubber alone, but when used in combination with the addition vulcanizing agent as an auxiliary vulcanizing agent, the physical properties of the resulting roller, such as strength and distortion, can be further improved.

[0029] Examples of organic peroxide vulcanizing agents include benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane. The amount of the organic peroxide vulcanizing agent is usually preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the resin composition for the elastic layer.

[0030] The addition vulcanizing agent is preferably used in combination with an addition reaction catalyst. Examples of the addition reaction catalyst include platinum black, platinic chloride, chloroplatinic acid, reaction products of chloroplatinic acid with monohydric alcohols, complexes of chloroplatinic acid with olefins, platinum bisacetoacetate, palladium-based catalysts, and rhodium-based catalysts. The amount of the addition reaction catalyst to be added can be a catalytic amount.

[0031] (e) Reaction inhibitor The resin composition for the elastic layer may contain a reaction inhibitor. The reaction inhibitor is a component that inhibits the crosslinking reaction of the silicone raw rubber at room temperature (e.g., 23°C). The reaction inhibitor may be, for example, a component that is deactivated or volatilized by heating. By including a reaction inhibitor, the resin composition for the elastic layer has a longer pot life and is easier to work with.

[0032] The reaction inhibitor can be appropriately selected from components that can inhibit the crosslinking reaction of the silicone rubber at room temperature, depending on the types of silicone rubber, vulcanizing agent, and curing accelerator blended into the resin composition for the elastic layer. For example, when the resin composition for the elastic layer contains a platinum catalyst, suitable reaction inhibitors that can be used include methylvinylcyclotetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohols, and hydroperoxides.

[0033] The amount of the reaction inhibitor to be added is not particularly limited and can be adjusted appropriately depending on the desired pot life, curing temperature, curing speed, etc. The amount of the reaction inhibitor to be added may be, for example, 0.5% by mass or more and 8.0% by mass or less, and preferably 1.0% by mass or more and 6.0% by mass or less, based on the total amount of the resin composition for the elastic layer.

[0034] The resin composition for the elastic layer may also contain various additives. Examples of the various additives include auxiliary agents such as chain extenders, catalysts, dispersants, antioxidants, antioxidants, and non-silica fillers such as glass beads, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers, flame retardancy improvers, acid acceptors, thermal conductivity improvers, mold release agents, and solvents. These various additives may be commonly used additives or may be specially used additives depending on the application.

[0035] -Molding- The elastic layer 3 is formed on the outer peripheral surface of the shaft 2 by extrusion molding using a resin composition for the elastic layer. Vulcanization and molding may be carried out simultaneously or successively. The diameter of the outer die of the extruder is not particularly limited, but it should be larger than the outer diameter of the product, and is preferably 1.0 mm or more larger.

[0036] -Vulcanization- The heating temperature when vulcanizing the resin composition for the elastic layer is preferably 100°C or higher and 500°C or lower, more preferably 120°C or higher and 300°C or lower. The heating time is preferably several seconds to 1 hour, more preferably 10 seconds to 35 minutes. If necessary, secondary vulcanization may be performed. Further, tertiary vulcanization may be performed at 180 to 280°C, particularly 200 to 250°C, for 1 to 15 minutes.

[0037] -Polishing- The elastic roller thus obtained is polished to the desired product outer diameter. In the polishing process, the shape of the elastic roller formed on the outer surface of the shaft is adjusted to a straight shape, a shape in which the thickness of the elastic roller in the axial direction of the shaft gradually increases toward the center of the shaft and gradually decreases from the center to the tip of the shaft (i.e., an inverted crown shape), or a shape in which the thickness of the elastic roller increases from the center of the shaft toward both ends of the shaft (i.e., an inverted crown shape).

[0038] The outer diameter of the elastic layer 3 is not particularly limited, and is preferably, for example, 6 mm or more and 25 mm or less, and more preferably 7 mm or more and 21 mm or less.

[0039] The thickness of the elastic layer 3 is not particularly limited, but is preferably 2 mm or more and 6 mm or less. In this specification, the thickness refers to the thickness in the direction perpendicular to the axial direction of the elastic roller 1.

[0040] A coating layer may be provided on the outer peripheral surface of the elastic layer 3. For the purpose of improving adhesion to the coating layer, the elastic layer 3 may be subjected to surface treatment such as primer treatment, corona treatment, plasma treatment, excimer treatment, UV treatment, itro treatment, or flame treatment.

[0041] By using the resin composition for the elastic layer, the elastic roller of the present invention can suppress the hardness deviation in the thickness direction of the elastic layer within a certain range. That is, in the elastic roller of the present invention, the difference between the surface roughness Rz when the elastic layer is polished to the outer diameter of the elastic roller to the product outer diameter + 1.2 mm after vulcanization and the surface roughness Rz when further polished to the product outer diameter is within ±0.5 μm. Therefore, even if the amount of polishing is minimized and the same amount of polishing as conventionally used, a uniform elastic layer can be formed, and therefore, by incorporating the elastic roller of the present invention into an image forming apparatus, high-quality images can be provided. [Example]

[0042] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples shown below.

[0043] [Example 1] The elastic roller of Example 1 was produced by the following procedure. (Formation of primer layer) An electroless nickel-plated shaft (made of SUM23, diameter 10 mm, length 274.2 mm) was washed with ethanol, and its surface was coated with a silicone primer (product name "Primer No. 16", manufactured by Shin-Etsu Chemical Co., Ltd.). The primer-treated shaft was baked in a gear oven at 150°C for 10 minutes and then cooled at room temperature for at least 30 minutes, forming a primer layer on the outer surface of the shaft.

[0044] (Formation of elastic layer) First, a resin composition for the elastic layer was prepared. Details of the resin composition for the elastic layer are as follows. Table 1 shows the formulation of the resin composition for the elastic layer and the molding conditions for the elastic layer. Millable silicone rubber Product name "KE-561U", manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Product name "KE-78VBS", manufactured by Shin-Etsu Chemical Co., Ltd.) 3.0 parts by mass 0.3 parts by mass of catalyst (product name "C-25A", manufactured by Shin-Etsu Chemical Co., Ltd.) Vulcanizing agent (product name "C-3", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 parts by mass Reaction retarder (product name "X-93-1115", manufactured by Shin-Etsu Chemical Co., Ltd.) 1.5 parts by mass

[0045] Next, the resin composition for the elastic layer was used to form an elastic layer on the outer peripheral surface of the elastic layer using an extrusion molding machine equipped with an outer die with a diameter of 15 mm. In the extrusion molding, the composition was heated in an infrared heating furnace (IR furnace) at 270°C for 10 minutes (primary vulcanization), and then further vulcanized by heating in a gear oven at 200°C for 4 hours (secondary vulcanization). This resulted in an elastic layer being formed on the outer peripheral surface of the elastic layer, producing an elastic roller base. The thickness of the elastic layer was 4 mm. [Example 2] An elastic roller base was produced in the same manner as in Example 1, except that the primary vulcanization of the extrusion molding was carried out in a nitrogen atmosphere.

[0046] [Comparative Example 1] An elastic roller base material was produced in the same manner as in Example 1, except that in the above elastic layer resin composition, the catalyst and vulcanizing agent were changed as follows, and heating was performed in an infrared heating furnace at 220° C. for 10 minutes. 0.5 parts by mass of catalyst (product name "C-25A", manufactured by Shin-Etsu Chemical Co., Ltd.) Vulcanizing agent (product name "C-3", manufactured by Shin-Etsu Chemical Co., Ltd.) 1.5 parts by mass

[0047] [Table 1]

[0048] [evaluation] The surface roughness Rz of the elastic roller raw material was measured in the following manner, and the difference in surface roughness Rz was determined. Table 2 shows the measurement results, and Figure 2 shows the relationship between the outer diameter of the elastic roller raw material and the surface roughness Rz. (Method for measuring surface roughness Rz) The surface roughness Rz was measured using a contact surface roughness measuring instrument (product name "Surfcom 1400G", manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with JIS B 0601:1994 under the conditions of a measurement length of 2.4 mm, a measurement speed of 0.15 mm / s, and a stylus tip radius of 2 μm, as the ten-point average roughness in the circumferential direction of the roller. This was taken as the surface roughness Rz. (1) The elastic roller raw material was polished to an outer diameter of 14.2 mm (product outer diameter + 1.2 mm), and the surface roughness Rz was measured. (2) Next, the outer diameter was polished to 13 mm (outer diameter of the product), and the surface roughness Rz was measured in the same manner as in (1) above. (3) Then, the difference was calculated by subtracting the surface roughness Rz of (2) from the surface roughness Rz of (1).

[0049] [Table 2]

[0050] As shown in Table 2, in Example 1, the difference between the surface roughness Rz when polished to an outer diameter of 14.2 mm (product outer diameter + 1.2 mm) and the surface roughness Rz when polished to an outer diameter of 13.0 mm {Rz(14.2) - Rz(13.0)} was -0.24 μm or less. In Example 2, the difference in surface roughness Rz was 0.13 μm. On the other hand, in Comparative Example 1, the difference in surface roughness Rz was 1.43 μm. That is, it is understood that the elastic roller of the present invention has an elastic layer formed after vulcanization that is uniform in the depth direction. [Explanation of symbols]

[0051] 1 Elastic roller 2-axis body 3 Elastic layer

Claims

1. An elastic roller comprising a shaft body and an elastic layer on the outer periphery of the shaft body, The elastic layer is formed by extrusion molding, vulcanization, and polishing, and the difference between the surface roughness Rz when the elastic roller is polished after vulcanization until the outer diameter of the elastic roller is the product outer diameter + 1.2 mm and the surface roughness Rz when the elastic roller is further polished to the product outer diameter is within ±0.5 μm.

2. 2. The elastic roller according to claim 1, wherein the elastic layer is made of silicone rubber.

3. 2. The elastic roller according to claim 1, wherein the elastic layer has a thickness of 2 mm or more.

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