JP2018197803A - Semiconductive sponge roller, method for manufacturing semiconductive sponge roller, and image forming apparatus - Google Patents

Abstract

To provide a semiconductive sponge roller that has low hardness and improved distortion characteristics, a method for manufacturing the semiconductive sponge roller, and an image forming apparatus including the semiconductive sponge roller.SOLUTION: The present invention provides a semiconductive sponge roller comprising a shaft body and an elastic layer formed on an outer peripheral surface of the shaft body, wherein the elastic layer is formed of millable type silicone rubber, a crosslinking agent, and a chemical foam agent; the external diameter return rate one hour later of the elastic layer measured by using a compression tester is 90% or more and 100% or less; the compressive stress relaxation rate 10 minutes later of the elastic layer measured by using a reactive loader is 35% or more and 55% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductive sponge roller and an image forming apparatus. More specifically, the present invention relates to a semiconductive sponge roller having low hardness and improved distortion characteristics, a method for manufacturing the semiconductive sponge roller, and the semiconductive The present invention relates to an image forming apparatus provided with a conductive sponge roller.

  Various types of image forming apparatuses using an electrophotographic system are employed in laser printers, copiers, video printers, facsimiles, and complex machines of these. An image forming apparatus using an electrophotographic system includes a shaft body and an elastic layer formed on an outer peripheral surface thereof, for example, a cleaning roller, a charging roller, a developing roller, a transfer roller, a pressure roller, a paper feed conveyance roller, Various sponge sponges for printing such as a fixing roller are provided.

  Among these sponge rollers, the cleaning roller, the toner supply roller, and the developing roller have conductivity for the purpose of adsorbing and transporting the developer. In order to reduce the load and friction, it is required to have a low hardness.

  As a low-hardness sponge roller, for example, Patent Document 1 discloses that a developing mechanism of an image forming apparatus that involves a developing operation with a developer rotates in contact with the surface of the developing roller to remove toner in a toner reservoir. A toner supply roller that carries the toner on the surface of the developing roller and supplies the toner to the surface of the developing roller. A developing roller is disclosed in which the cell film is broken and a predetermined range in the central portion of the roller is set to be lower in hardness than both ends of the roller.

  Patent Document 2 includes a shaft body having conductivity and a cylindrical conductive rubber body having conductivity and provided on the outer peripheral surface of the shaft body, and the conductive rubber body includes: Disclosed is a conductive roller characterized in that a metal fiber assembly in which metal fibers having flexibility are entangled is embedded so that the shaft body and the outer peripheral surface of the conductive rubber body are electrically connected. Yes.

JP 2007-65103 A JP 2007-256410 A

  However, since the sponge rollers described in Patent Document 1 and Patent Document 2 have low hardness, the elastic layer is likely to be distorted with time, thereby reducing the durability of the sponge roller. It was. Accordingly, the present invention has been made in view of the above problems, and is a semiconductive sponge roller having a low hardness and improved distortion characteristics, a method for producing the semiconductive sponge roller, and the semiconductive property. An object is to provide an image forming apparatus provided with a sponge roller.

  The inventors of the present invention have intensively studied to solve the above problems. As a result, in the semiconductive sponge roller, it has been found that the above problems can be solved by adjusting the outer diameter return rate and the compressive stress relaxation rate of the elastic layer, and the present invention has been completed. Specifically, the present invention provides the following.

  (1) A first aspect of the present invention is a semiconductive sponge roller having a shaft body and an elastic layer formed on an outer peripheral surface of the shaft body, wherein the elastic layer includes a millable silicone rubber, The outer diameter return rate after 1 hour of the elastic layer is 90% or more and 100% or less using a compression tester, formed from a crosslinking agent and a chemical foaming agent, and using a repulsive load machine, The semiconductive sponge roller has a compressive stress relaxation rate of 35% or more and 55% or less after 10 minutes of the elastic layer.

  (2) A second aspect of the present invention is the semiconductive sponge roller according to (1), wherein the elastic layer has an Asker F hardness of 30 or more and 70 or less. .

  (3) A third aspect of the present invention is the semiconductive sponge roller according to (1) or (2), wherein the blending ratio of the dimethyl silicone raw rubber to 100 parts by weight of the millable silicone rubber is 0 parts by weight. The amount is 140 parts by mass or less.

  (4) According to a fourth aspect of the present invention, a millable silicone rubber, a crosslinking agent, and a chemical foaming agent are mixed to prepare a mixture, and the mixture is extruded on the outer surface of the shaft body. Next, a method for producing a sponge roller is characterized in that the semiconductive sponge roller according to any one of (1) to (3) is produced by heat curing.

  (5) A fifth aspect of the present invention is an image forming apparatus including the semiconductive sponge roller according to any one of (1) to (3).

  The semiconductive sponge roller of the present invention has an outer diameter recovery rate of 90% or more and 100% or less after 1 hour of the elastic layer using a compression tester, and 10 minutes after the elastic layer using a repulsive load machine. Since the compression stress relaxation rate is adjusted to be 35% or more and 55% or less, the strain characteristic is improved while the hardness is low.

It is explanatory drawing which shows the semiconductive sponge roller which shows one Example of this invention. FIG. 2 is an explanatory view showing an example of an image forming apparatus in which a semiconductive sponge roller showing an embodiment of the present invention is incorporated in a fixing device. 4 is a view showing a compression tester for measuring an outer diameter return rate of an elastic layer in the semiconductive sponge roller of the present invention.

<Semi-conductive sponge roller>
As shown in FIG. 1, a semiconductive sponge roller 1 that is an example of the present invention includes a shaft body 2 that is also called a cored bar, and an elastic layer 3 formed on the outer peripheral surface of the shaft body.

[Shaft]
The shaft body is a long cylindrical body called a so-called metal core that is usually formed of iron, aluminum, stainless steel, brass, or the like. The shaft body is adjusted to an appropriate diameter and axial length according to the image forming apparatus to be mounted.

  When a sponge roller is incorporated in the image forming apparatus, the shaft body usually has a diameter of 5.0 mm or more and 40 mm or less, and the shaft length from one end to the other end is usually 120 mm or more and 1000 mm or less.

[Elastic layer]
The elastic layer is formed of millable silicone rubber, a crosslinking agent, and a chemical foaming agent.

(Millable silicone rubber)
Millable silicone rubber is similar to unvulcanized compounded rubber of natural rubber and ordinary synthetic rubber in a state before curing, and can be plasticized and mixed with a kneading roll machine or a closed mixer. Silicone rubber compound.

  A suitable millable silicone rubber contains the following components (A) to (E).

(A) Organopolysiloxane having a polymerization degree of 100 or more represented by the following average composition formula (I): R ¹ _a SiO _{(4-a) / 2} (I)
(In the formula, R ¹ represents the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 or more and 2.05 or less.)
(B) Reinforcing silica having a specific surface area of 50 m ² / g or more by BET adsorption method (C) Alkoxysilane represented by the following general formula (II) R ² mSi (OR ³ ) _4-m (II)
Wherein R ² is independently a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, R ³ is the same or different unsubstituted or substituted alkyl group, and m is 0, 1, 2, or 3)
(D) Water (E) Hexaorganodisilazane represented by the following general formula (III) R ⁴ ₃ SiNHSiR ⁴ ₃ (III)
(In the formula, R ⁴ represents the same or different monovalent hydrocarbon groups.)

  As the millable silicone rubber in the present invention, specifically, KE-571-U, KE-1571-U, KE-904FU, KE-951-U, KE-541-U, manufactured by Shin-Etsu Chemical Co., Ltd., KE-551-U, KE-561-U, KE-961T-U, KE-1541-U, KE-1551-U, KE-941-U, KE-971T-U, and the like can be used.

  In the semiconductive sponge roller of the present invention, dimethyl silicone raw rubber can be blended. The blending ratio of the dimethyl silicone raw rubber with respect to 100 parts by mass of the millable silicone rubber is preferably 0 parts by mass or more and 140 parts by mass or less, and more preferably 0 parts by mass or more and 100 parts by mass or less. By adjusting the blending ratio of the dimethyl silicone raw rubber to the millable silicone rubber in this way, the outer diameter return rate and the compressive stress relaxation rate, which will be described later, can be adjusted to a predetermined range, and as a result, the hardness is low. Thus, a semiconductive sponge roller having improved distortion characteristics can be obtained.

(Crosslinking agent)
In the semiconductive sponge roller of the present invention, a crosslinking agent is used for forming the elastic layer. Examples of the crosslinking agent include addition reaction crosslinking agents and organic peroxide crosslinking agents.

  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. An addition reaction crosslinking agent can be used individually by 1 type or in mixture of 2 or more types. The addition amount of the addition reaction crosslinking agent with respect to 100 parts by mass of the millable silicone rubber is preferably 1 part by mass or more and 5 parts by mass or less, and more preferably 2 parts by mass or more and 4 parts by mass or less.

  When the above addition reaction crosslinking agent is used, the organic peroxide crosslinking agent can be used alone to crosslink the millable silicone rubber, but when used as an auxiliary crosslinking agent for the addition reaction crosslinking agent, a sponge is obtained. The physical properties such as the strength and strain of the roller can be further improved. Examples of the organic peroxide crosslinking agent include benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis. (T-butylperoxy) hexane and the like. The amount of the organic peroxide crosslinking agent added to 100 parts by mass of the millable silicone rubber is preferably 2 parts by mass or more and 10 parts by mass or less, and more preferably 3 parts by mass or more and 8 parts by mass or less. An organic peroxide crosslinking agent can be used individually by 1 type or in mixture of 2 or more types.

  The addition reaction crosslinking agent is preferably used in combination with an addition reaction catalyst. Addition reaction catalyst is platinum black, platinous chloride, chloroplatinic acid, reaction product of chloroplatinic acid and monohydric alcohol, complex of chloroplatinic acid and olefins, platinum bisacetoacetate, palladium catalyst, rhodium catalyst Etc. In addition, the compounding quantity of this addition reaction catalyst can be made into a catalyst quantity.

(Chemical foaming agent)
In the semiconductive sponge roller of the present invention, a chemical foaming agent is used for forming the elastic layer. The compounding amount of the chemical foaming agent with respect to 100 parts by mass of the millable silicone rubber before crosslinking and curing is preferably 0.5 parts by mass or more and 10 parts by mass or less, and more preferably 3 parts by mass or more and 8 parts by mass or less. . The chemical foaming agent in the present invention may be a foaming agent conventionally used for forming an elastic layer. Examples of the inorganic foaming agent include sodium bicarbonate and ammonium carbonate. Examples of the organic foaming agent include diazoamino derivatives. And organic azo compounds such as an azonitrile derivative and an azodicarboxylic acid derivative. Among organic azo compounds, azodicarboxylic acid amide, azobis-isobutyronitrile and the like are preferably used. In particular, azobis-isobutyronitrile can be preferably used.

[Outside diameter recovery rate]
In the semiconductive sponge roller of the present invention, the outer diameter return rate after 1 hour of the elastic layer using the compression tester 60 is 90% or more and 100% or less. By adjusting the outer diameter return rate within this range, it is possible to obtain a semiconductive sponge roller with low hardness but improved distortion characteristics. In the measuring method of the outer diameter return rate, a compression tester 60 shown in FIG. 3 is used. First, the outer diameter of the semiconductive sponge roller is measured at room temperature with a laser measuring machine. As shown in FIG. 3, the semiconductive sponge roller is sandwiched between the compression plate 61 and the compression plate 61, and the handle 63 is turned and tightened. The thickness of the spacer 62 (the length from the upper end surface of the spacer 62 in contact with the upper compression plate 61 to the lower end portion of the spacer 62 in contact with the lower compression plate 61) is 10 mm, and is matched to the thickness of the spacer 62. Then, turn the handle 63 to tighten it. With the semiconductive sponge roller fastened by the compression tester 60, the compression tester 60 is put into a dryer at 100 ° C. and heated as it is for 8 hours. After 8 hours have passed, the compression device is taken out from the dryer, and immediately after the semiconductive sponge roller is removed from the compression tester 60 and left at room temperature for 1 hour, the outer diameter of the semiconductive sponge roller is measured with a laser measuring machine. Measure with The outer diameter return ratio (%) is a value calculated by the formula of outer diameter of the semiconductive sponge roller after compression / outer diameter of the semiconductive sponge roller before compression × 100.

[Compressive stress relaxation rate]
In the semiconductive sponge roller of the present invention, the compression stress relaxation rate after 10 minutes of the elastic layer using a repulsive load machine is 35% or more and 55% or less. By adjusting the compression stress relaxation rate within this range, it is possible to obtain a semiconductive sponge roller with low hardness and improved distortion characteristics. Using a repulsive load machine, measure the indentation load of 1mm from the surface of the semi-conductive sponge roller with a 25.2 mm diameter pusher, measure the load after 10 minutes, load after 10 minutes / load immediately after indentation × 100 The value calculated by the formula is defined as the compression stress relaxation rate (%).

[Asker F hardness]
The elastic layer preferably has an Asker F hardness of 30 or more and 70 or less, and more preferably 35 or more and 55 or less. When the Asker F hardness is within such a range, a low-hardness semiconductive sponge roller can be obtained, and the load on the developer and friction during pressure bonding between the rollers can be reduced. The Asker F hardness is a value obtained by pressing the center part of the presser of the hardness meter against the curved surface of the roller as the object to be measured and reading the scale at the moment when the reference surface contacts the surface of the roller. is there. Actually, it can be measured by “Asker rubber hardness meter F type” manufactured by Kobunshi Keiki Co., Ltd.

[Dimensions of elastic layer, etc.]
The elastic layer is formed in a cylindrical shape on the outer peripheral surface of the shaft body, and the thickness of the elastic layer is usually 0.5 mm to 30 mm, preferably 1 mm to 15 mm.

[Others]
As long as the object of the present invention can be achieved, the elastic layer has a low molecular siloxane ester, a silanol, for example, a dispersant such as diphenylsilanediol, and a heat resistance improver such as iron oxide, cerium oxide, and iron octylate Further, various carbon functional silanes for improving adhesiveness and moldability, halogen compounds for imparting flame retardancy, and the like may be contained within a range not impairing the object of the present invention.

<Manufacturing method of sponge roller>
The sponge roller according to the present invention can be manufactured by the manufacturing method according to the present invention.

  In the production method according to the present invention, millable silicone rubber, a crosslinking agent of 2 to 10 parts by mass with respect to 100 parts by mass of the millable silicone rubber, and a chemical foaming agent are blended.

  The types of millable silicone rubber, crosslinking agent, chemical foaming agent, etc. have already been described.

  The mixing method is not particularly limited, and examples thereof include a method in which a millable silicone rubber, a chemical foaming agent, and a cross-linking agent are added sequentially or all at once at room temperature and normal pressure and mixed uniformly with a stirrer, a kneader, or the like. Can be mentioned. In this way, the step of preparing the mixture is completed.

  Various additives can be included in the mixture. As various additives, for example, auxiliary agents such as chain extenders, catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers , Heat resistance improver, flame retardant improver, acid acceptor, thermal conductivity improver, release agent, solvent and the like. These various additives may be commonly used additives or may be specially used additives depending on applications.

  The above mixture is, for example, several minutes to several hours, preferably 5 minutes until it is uniformly mixed using a rubber kneader such as a two-roll, three-roll, roll mill, Banbury mixer, or dough mixer (kneader). It can be obtained by kneading at room temperature or under heating for 1 hour or less.

  Next, the obtained mixture is heat-molded on the outer peripheral surface of the shaft body constituting the sponge roller by continuous heat molding by extrusion molding, pressing, mold molding by injection, or the like.

  After the mixture is formed in a cylindrical shape on the outer surface of the shaft body, the cylindrical mixture, in other words, the cylindrical shaped body is heated and vulcanized together with the shaft body (heat curing).

  It is particularly preferable that the heating during vulcanization by heating the molded body is as follows. That is, as primary vulcanization, heating is performed from 100 ° C. to 300 ° C., particularly from 150 ° C. to 250 ° C. for 5 minutes to 30 minutes, and then as secondary vulcanization, from 180 ° C. to 250 ° C., particularly from 200 ° C. to 230 ° C. Heat for 10 hours. Heating in such a plurality of times is preferable because it is possible to control the decomposition of the chemical foaming agent, the curing of the millable silicone rubber, and the removal of the remaining low-molecular siloxane as necessary.

  Heating necessary for vulcanization can be performed by a heating furnace such as an infrared heating furnace or a hot air furnace, a heating machine such as a dryer, or the like.

  The sponge roller thus obtained may be further subjected to a polishing process. In the polishing process, the thickness of the sponge roller formed on the outer peripheral surface of the shaft body is gradually increased in the axial direction of the shaft body toward the center of the shaft body. It is a step of adjusting the shape gradually decreasing toward the tip, that is, the crown shape, or the shape increasing the thickness of the sponge roller from the center of the shaft toward both ends of the shaft, that is, the reverse crown shape or the straight shape. .

<Image forming apparatus>
The semiconductive sponge roller according to the present invention can be incorporated in, for example, a fixing device of an image forming apparatus.

  Next, with reference to FIG. 2, an example of an image forming apparatus (hereinafter sometimes referred to as an image forming apparatus according to the present invention) in which a fixing device having a semiconductive sponge roller according to the present invention is provided is provided. ,explain.

  As shown in FIG. 2, the image forming apparatus 30 according to the present invention is arranged around a rotatable image carrier 31, for example, a photoreceptor, on which an electrostatic latent image is formed, and the image carrier 31. A charging unit 32 such as a charging roller, an exposure unit 33, a developing unit 40, a transfer unit 34 such as a transfer roller, a cleaning unit 37 such as a cleaning roller, and a fixing unit 35 are provided on the downstream side 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. 2, the developer accommodating portion 41 and the developer 42 are supplied to 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 shown in FIG. 2, the fixing unit 35 includes a fixing roller 53 and an endless belt support roller disposed in the vicinity of the fixing roller 53 in a housing 50 having an opening 52 through which the recording medium 36 passes. 54, an endless belt 55 wound around the fixing roller 53 and the endless belt support roller 54, a pressure roller 56 pressed against the fixing roller 53 via the endless belt 55, and the endless belt 55 in a non-contact manner. And a heating unit that heats the fixing roller 53 from the outside via the endless belt 55, and is rotatable so that the fixing roller 53 and the pressure roller 56 are in contact with or pressed against each other via the endless belt 55. This is a pressure heat fixing device supported.

  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. The endless belt 55 may be an endless belt formed of, for example, a resin such as polyamide or polyamideimide, and the thickness and the like of the endless belt 55 can be appropriately adjusted to match the fixing unit 35. The pressure roller 56 is in pressure contact with the fixing roller 53 via an endless belt 55 by a biasing means (not shown) such as a spring. As the heating means, a radiant heating method using a halogen heater, a reflector, or the like, a direct contact heating method in which heating is performed by directly contacting a heater or the like, an induction heating method, or the like is adopted. This heating means is a member having a length substantially the same as the length of the fixing roller 53 in the axial direction, and may be disposed in any of the fixing means 35. However, as shown in FIG. It is preferable that the fixing roller 53 be arranged substantially in parallel with a predetermined interval. A heating coil is used in the induction heating method, and this heating coil is usually a ferromagnetic material such as ferrite, and is a typical shape used for a switching power supply. I type, E type, and U type Etc., and a conducting wire is wound. 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 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 unit 40 to the image carrier 31 to develop the electrostatic latent image, and the developer image is conveyed between the image carrier 31 and the transfer unit 34 on the recording member 36. Is transferred to. The semiconductive sponge roller of the present invention can be suitably used for, for example, the developer supply means 43 and the developer carrier 44, and has low hardness, so that the load and friction on the developer are reduced. Furthermore, since the distortion characteristics are also improved, the durability is excellent. 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.

  In the fixing unit 35 and the image forming apparatus 30, the fixing roller 53 or the pressure roller 56 is excellent in fixing performance for fixing the developer on the recording medium and consumes less power.

  The semiconductive sponge roller and the image forming apparatus according to the present invention are not limited to the above-described embodiments, and various modifications are possible within the scope that can achieve the object of the present invention.

  For example, in the semiconductive sponge roller 1, the elastic layer 3 has a single layer structure, but in the present invention, it may have a multilayer structure of two or more layers.

  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. As the color image forming apparatus, for example, 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 And a tandem type color image forming apparatus in which the toner is disposed in series on an intermediate transfer member 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 fixing unit 35 and the image forming apparatus 30, a one-component developer is advantageously used as the developer 42, but a two-component developer containing a toner and a carrier such as iron or nickel is also used. can do.

(Examples 1 to 3, Comparative Examples 1 and 2)
In Examples 1 to 3 and Comparative Examples 1 to 2, the base rubber material shown in Table 1, the dimethyl silicone raw rubber shown in Table 1, the cross-linking agent shown in Table 1, and The catalyst and the chemical foaming agent shown in Table 1 were sufficiently kneaded with two rolls in the blending amounts shown in Table 1 to obtain a mixture.

  The base rubber materials used in Examples 1 to 3 and Comparative Examples 1 to 2 were a silicone foam rubber composition “KE-904FU” (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) 75 containing no conductivity-imparting agent. This is a millable silicone rubber in which part by mass and 25 parts by mass of a conductivity imparting agent “KE-87C40PU” (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) are kneaded. The dimethyl silicone raw rubber described in Table 1 is KE-76VBS (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), and the “crosslinking agent” described in Table 1 is a commercial name C- manufactured by Shin-Etsu Chemical Co., Ltd. It is an addition reaction crosslinking agent that is 25B, and the “catalyst” described in Table 1 is a platinum catalyst that is trade name C-25A manufactured by Shin-Etsu Chemical Co., Ltd., and the “chemical foaming agent” described in Table 1 Is AIBN of the brand name AZO series manufactured by Otsuka Chemical Co., Ltd. In addition, the compounding ratio (parts by mass) of each material other than the base rubber material shown in Table 1 indicates the parts by mass with respect to 100 parts by mass of the millable silicone rubber.

  Next, the shaft body on which the primer layer is formed and the mixture are integrally extracted by an extruder, and in Examples 1 to 3 and Comparative Examples 1 to 2, the above mixture is used using an infrared heating furnace (IR furnace). Was subjected to primary vulcanization by heating at 225 ° C. for 17 minutes, and then subjected to secondary vulcanization at 225 ° C. for 7 hours in a hot air drying furnace to produce a foam roller base body. The circumferential surface of the foam roller base was subjected to high-speed polishing with a metal grindstone using a polishing machine manufactured by Mizuguchi Seisakusho.

  The manufactured sponge roller was measured for outer diameter return rate, compression stress relaxation rate, Asker F hardness, and the results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Sponge roller 2 Shaft body 3 Elastic layer 30 Image forming apparatus 31 Image carrier 32 Charging means 33 Exposure means 34 Transfer means 35 Fixing means 36 Recording body 37 Cleaning means 40 Developing means 41 Developer storage part 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 60 Compression tester 61 Compression plate 62 Spacer 63 Handle

Claims (5)

A semiconductive sponge roller having a shaft body and an elastic layer formed on the outer peripheral surface of the shaft body,
The elastic layer is formed from a millable silicone rubber, a crosslinking agent, and a chemical foaming agent,
Using a compression tester, the outer diameter return rate after 1 hour of the elastic layer is 90% or more and 100% or less,
A semiconductive sponge roller using a repulsion load machine, wherein the compressive stress relaxation rate after 10 minutes of the elastic layer is 35% or more and 55% or less.   The semiconductive sponge roller according to claim 1, wherein the elastic layer has an Asker F hardness of 30 or more and 70 or less.   The semiconductive sponge roller according to claim 1 or 2, wherein a blending ratio of the dimethyl silicone raw rubber with respect to 100 parts by mass of the millable silicone rubber is 0 parts by mass or more and 140 parts by mass or less.   A millable silicone rubber, a cross-linking agent, and a chemical foaming agent are mixed to prepare a mixture, and the mixture is extruded on the outer surface of the shaft body and then heat-cured, and A method for producing a semiconductive sponge roller, comprising producing any of the semiconductive sponge rollers.   An image forming apparatus comprising the semiconductive sponge roller according to claim 1.

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