JP2007304410A - Semi-conductive roller and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semi-conductive roller superior in any of elasticity, dimension stability, adhesion durability, electric homogeneity, and toner adhesion properties required in the semi-conductive roller such as a developing roller, and to provide an image forming apparatus having high resolution without unevenness in printing by supplying toner to a photoreceptor drum without excess or deficiency utilizing the semi-conductive roller. <P>SOLUTION: The semi-conductive roller includes an elastic body layer including a filler around an axial body, having semi-conductivity, and having air holes on the surface, wherein the mean hole diameter of the air holes is 57-84% of the mean toner diameter, and the number of air holes is 30-70 in 11,200 μm<SP>2</SP>. The image forming apparatus is equipped with the same. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductive roller and an image forming apparatus. The present invention relates to a mounted image forming apparatus.

  For example, various image forming apparatuses using an electrophotographic system are employed in laser printers, copying machines, facsimile machines, and the like. As an example of the image forming apparatus, FIG. 3 shows an outline of a monochrome printer, and FIG. 4 shows a main configuration of a developing apparatus including the photosensitive drum and the developing roller. The developing principle will be described with reference to FIG. 4. The toner 19 is supplied to the latent image formed on the photosensitive drum 13 by the developing roller 11 and developed, and the developed toner 20 on the photosensitive drum 13 is brought into contact with the lower portion of the photosensitive drum 13. Transfer to the recording paper 14. In FIG. 3, the recording paper 14 to which the toner 20 is transferred from the photosensitive drum 13 at the center of the figure moves to the left in the figure, and the toner transferred by the pressure roller and the fixing roller is heat-pressed and fixed. Then, images such as characters and figures are completely fixed on the recording paper 14, and printing on the surface of the recording paper 14 is completed. In the case of a color printer, as shown in FIG. 5, the BK, C, M, and Y developing devices are arranged in tandem along the recording paper conveyance direction in the image forming apparatus, and each color toner is developed. The toner is quantitatively supplied from the roller to the photosensitive drum, and a toner image of each color is transferred from the photosensitive drum to a transfer belt to form a multicolor image.

  In such an image forming apparatus, the developing roller must be able to always supply the raw material toner uniformly to the photosensitive drum. If the toner is uniformly supplied to the surface of the photosensitive drum, the latent image on the photosensitive drum is finely developed with the toner and transferred onto the recording paper. Referring to FIG. 4, the movement of the toner in the developing portion will be described in detail. The toner 18 charged by the toner supply roller 17 adheres to the developing roller 11 by electrostatic force and physical adhesion force, and the rotating developing roller 11 rotates. The toner 18 adhering to the surface becomes a layer of toner 19 formed with a constant thickness by the developing blade 12 and reaches the rotating photosensitive drum 13 substantially in contact with the developing roller 11. The photosensitive drum 13 is charged by a charging roller 16, and a latent image is drawn thereon. The toner 19 in contact with the latent image portion on the charged photosensitive drum 13 adheres to the photosensitive drum 13 side by electrostatic force and develops the latent image. The toner 20 developed on the photosensitive drum 13 contacts the recording paper 14 as the photosensitive drum 13 rotates and is transferred onto the recording paper 14 by the transfer roller 15. At this time, as described above, it is important that the toner 19 supplied by the developing roller 11 always contacts the photosensitive drum 13 in a uniform state and adheres to the photosensitive drum 13 side by controlled electrostatic force. For this purpose, the developing roller is required to have excellent elasticity, dimensional stability, electrical characteristics, etc., and these properties do not change for a long time and have a long life.

  As described above, the developing roller is an important part for high-resolution printing without uneven printing. For this reason, various studies have been made on the optimization of the performance, the manufacturing method, the manufacturing mold, and the like of the developing roller. For example, Patent Documents 1 and 3 improve a roller molding die to provide a rubber roller having excellent dimensional stability and homogeneity. Patent Document 2 discloses a developing roller having low hardness and excellent deformation resistance, adhesion resistance, and electrical characteristics, and Patent Document 4 discloses a developing roller having little variation in conductivity. Patent Document 5 discloses a resin composition suitable for a developing roller having a surface roughness and a hardness excellent in toner transportability corresponding to a high-resolution electrophotographic apparatus.

  Further, in the conventional development of the developing roller, the surface of the elastic layer in the semi-finished developing roller taken out from the production mold is polished (polished) for the purpose of adjusting the surface roughness of the developing roller. After a polishing step called grinding and sometimes called cutting), final processing for obtaining a developing roller as a finished product was performed.

JP 2000-271938 A JP 2003-84561 A JP 2004-74430 A JP-A-6-221321 JP 2002-338808 A

  The present invention satisfies or improves the performance such as elasticity, dimensional stability, adhesion resistance, and electrical characteristics required for the developing roller, and further has a stable toner adhesion performance and can be used for the developing roller. It is an object to provide a semiconductive roller. Another object of the present invention is to provide an image forming apparatus with high resolution and no printing unevenness by stably supplying toner to the photosensitive drum using the semiconductive roller.

As means for solving the problems of the present invention,
The first aspect of the present invention is a semiconductive roller including an elastic body layer including a filler and having a semiconductivity around a shaft body, and having a hole on a surface thereof, wherein the average hole diameter of the holes is an average toner diameter. A semi-conductive roller having 57 to 84% of the number of holes and 30 to 70 in 11200 μm ² ,
2. The semiconductive roller according to claim 1, wherein the average toner diameter is 3 to 20 μm.
Claim 3 is the semiconductive roller according to claim 1 or 2, wherein at least one coat layer is provided on the surface of the elastic layer.
Claim 4 is the semiconductive roller according to any one of claims 1 to 3, wherein the filler is calcium carbonate.
A fifth aspect of the present invention is an image forming apparatus provided with the semiconductive roller according to any one of the first to fourth aspects.

  The surface of the semiconductive roller of the present invention is controlled, and the physical adhesion performance of the toner is stable. Therefore, it is easy to control the amount of toner transported by the electrostatic force to the photosensitive drum, and the electrophotographic roller It is possible to prevent uneven printing and poor resolution of the apparatus. In addition, the semiconductive roller of the present invention can be used not only by a conventional developing roller manufacturing method but also by conventional polishing (as described above, this “polishing” is called “grinding” or “cutting”). It is possible to efficiently produce by extrusion molding, injection molding, etc., omitting the final processing step performed after. Therefore, the image forming apparatus equipped with the semiconductive roller of the present invention has less printing unevenness and dirt, and can easily cope with higher resolution.

  The semiconductive roller of the present invention is formed by forming a semiconductive elastic layer including a filler around a shaft body, and a large number of holes exist on the surface of the elastic layer. In the semiconductive roller of the present invention, the pores have the effect of expanding the area of the elastic layer surface to which the toner is to be adhered, and the physical adhesion force of the toner is improved and stable. For this reason, the semiconductive roller of the present invention causes toner to adhere uniformly and quantitatively to the surface of the semiconductive roller with electrostatic force and physical adhesion force, and conveys the toner onto the photosensitive drum, which is precisely applied to the photosensitive drum. It can be adhered to the surface without excess or deficiency.

  Further, it should be noted that the semiconductive roller of the present invention has pores having an average particle size smaller than the average particle size of the toner particles on the surface of the elastic layer. As will be described in detail later, these pores can be suitably formed, for example, when the filler forming the elastic layer drops off from the surface of the elastic layer.

The pores formed on the surface of the elastic layer in the semiconductive roller of the present invention usually have an average pore diameter of 57 to 84%, preferably 66 to 82% with respect to the average toner diameter. More preferably, it is 73 to 82%. Since the average particle diameter of normal toner is approximately 3 to 20 μm, it is preferable that the average hole diameter of the pores existing on the surface of the elastic layer is in the above range with respect to the average toner diameter. If the average hole diameter of the holes is larger than 84% of the average toner diameter, the toner will easily enter the holes, and the toner that has entered the toner will not be easily transferred to the photosensitive drum. In addition, if the average pore diameter of the pores is smaller than 57% with respect to the average toner diameter, the toner particles cannot be effectively charged, and the image quality formed by the image forming apparatus May decrease. In addition, the average hole diameter of a hole is an observation screen observed with a scanning electron microscope, and is the arithmetic average of the hole diameters obtained by measuring the hole diameter of each hole existing in an area of 11200 μm ² .

In the present invention, the number of pores formed on the surface of the elastic layer is usually 30 to 70, preferably 30 to 65, and more preferably 45 in an area of 11200 μm ^2. ~ 65. If the number of holes is larger than the upper limit, toner particles conveyed by the semiconductive roller may become coarse and dense, and may cause unevenness in the image formed by the image forming apparatus. The ratio of calcium carbonate in the elastic layer is also increased and the hardness is increased. As a result, a defective developing roller may be formed. If the number of holes is less than the lower limit, the amount of toner particles transferred from the semiconductive roller to the photosensitive drum is reduced, and it becomes difficult to form an image with a predetermined density on the surface of the recording medium. is there.

  The elastic layer in the present invention is formed of an elastic body obtained by dispersing the filler in a rubber material.

  Examples of the rubber material include silicone rubber or silicone-modified rubber, natural rubber, nitrile rubber, ethylene propylene rubber (including ethylene propylene diene rubber), ethylene / propylene terpolymer (EPDM), styrene butadiene rubber, acrylonitrile / butadiene rubber, Rubber materials such as butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, fluorine rubber, polyether rubber, polyurethane, polystyrene / polybutadiene block polymer, polyolefin, polyethylene, chlorinated polyethylene And elastomers such as ethylene / vinyl acetate copolymer, and one or two or more mixed rubbers or modified rubbers can be used. In addition, as the rubber material described above, a millable type or liquid type material can be arbitrarily selected, and a millable type material is particularly preferable.

  Among the rubber materials, a cured body of the following silicone rubber composition that is a millable type is preferable.

The silicone rubber composition comprises (A) the following average composition formula (1):
R _n SiO _{(4-n) / 2} (1)
(However, R is the same or different substituted or unsubstituted monovalent hydrocarbon group, Preferably it is C1-C12, More preferably, it is C1-C8 monovalent hydrocarbon group. , N is a positive number from 1.95 to 2.05.)
And (B) a filler having a Mohs hardness of 2 to 8, and (C) a conductive material other than those belonging to the component (B).

  In the average composition formula (1), examples of the monovalent hydrocarbon group represented by R include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group, and dodecyl group, and cyclohexyl group. An alkenyl group such as a cycloalkyl group, a vinyl group, an allyl group, a butenyl group, and a hexenyl group; an aryl group such as a phenyl group and a tolyl group; an aralkyl group such as a β-phenylpropyl group; and a carbon atom of these groups. Examples thereof include a chloromethyl group, a trifluoropropyl group, and a cyanoethyl group in which part or all of the bonded hydrogen atoms are substituted with a halogen atom or a cyano group.

The organopolysiloxane is preferably end-capped with a trimethylsilyl group, a dimethylvinyl group, a dimethylhydroxysilyl group, a trivinylsilyl group, or the like. The organopolysiloxane preferably has at least two alkenyl groups in the molecule, specifically, 0.001 to 5 mol%, particularly 0.01 to 0.5 mol% of alkenyl groups in R, For example, it preferably has a vinyl group, an allyl group, a butenyl group, a hexenyl group, and the like, and particularly preferably has a vinyl group. In particular, when using a combination of a platinum-based catalyst and an organohydrogenpolysiloxane as a curing agent to be described later, an organopolysiloxane having such an alkenyl group is usually used. Ring-opening polymerization by cohydrolyzing and condensing one or more selected organohalosilanes or cyclic polysiloxanes such as siloxane trimers or tetramers using alkaline or acidic catalysts Can be obtained. This organopolysiloxane is basically a linear diorganopolysiloxane, but may be partially branched. Further, it may be a mixture of two or more different molecular structures. This organopolysiloxane usually has a viscosity of 100 cSt or more at 25 ° C., preferably 100,000 to 10,000,000 cSt. The organopolysiloxane usually has a degree of polymerization of 100 or more, preferably 3,000 or more, and an upper limit of preferably 100,000, and more preferably 10,000.

  Unlike the reinforcing filler such as reinforcing silica, the filler as the component (B) is added for the purpose of generating pores having a smaller pore diameter than the toner particles on the surface of the elastic layer. The Suitable fillers in the present invention include metals such as aluminum silicate, aluminum hydroxide, alumina, quartz powder, fused quartz powder, glass powder, diatomaceous earth, calcium carbonate, clay, silicon nitride, silicon carbide, titanium dioxide and zinc oxide. Examples thereof include oxides, among which diatomaceous earth, calcium carbonate, zinc oxide and the like are preferable, and calcium carbonate is particularly preferable. The Mohs hardness of calcium carbonate is generally about 3. As the calcium carbonate, both natural products and synthetic products can be used, and a pulverized product is preferred regardless of which is used. Precipitated calcium carbonate produced as a powder from a solution containing calcium ions is also suitable, and pulverized products such as limestone, calcite, and marble can also be used.

  Conductive substances such as metal fine particles, conductive metal oxide-based fine particles, and graphite can also be used as the filler as the component (B). Examples of the conductive metal oxide-based fine particles include conductive zinc oxide, white conductive titanium oxide, tin oxide, and antimony oxide-based fine particles. Specific examples of the conductive zinc oxide include oxides manufactured by Hakusui Tech Co., Ltd. Since zinc 23-K has a small primary particle size and a Mohs hardness of 4 to 5, it can be suitably used. As white conductive titanium oxide, for example, ET-500W (manufactured by Ishihara Sangyo Co., Ltd.) Can be mentioned. Examples of graphite include amorphous graphite and spherical graphite.

  Further, the hardness of the filler itself is usually 2 to 8 in Mohs hardness, preferably 3 to 6.5, and particularly preferably 4 to 5. When a filler with a Mohs hardness of 2 to 8 is used, even if there is some coarse particle size filler in the material, the filler part and the surrounding part should be polished to the same height by polishing. As a result, the surface roughness of the surface of the elastic layer other than the pores can be made finer. If the filler is too hard, the surface of the elastic layer will be convex or concave due to the filler during polishing, and toner etc. will not adhere to the convex part, and toner will accumulate in the concave part and the layer thickness will be uniform Hard to become. Furthermore, the convex filling material wears or damages the photosensitive drum, other rollers, or the like that contacts the roller surface. On the other hand, if the filler is too soft, the filler itself is often shaved more than the surroundings, resulting in a gentle concave shape, and it is difficult to make the layer thickness uniform. By using such a filler, the present invention forms pores smaller than the particle size of the toner particles on the surface of the elastic layer and smoothes the surface of the elastic layer other than the pores. A semiconductive roller having an elastic layer having a surface state is provided.

  The amount of component (B) added is preferably 1 to 500 parts by weight, more preferably 5 to 300 parts by weight, per 100 parts by weight of component (A). In particular, when the component (B) is an insulating filler, the content is preferably 5 to 100 parts by mass, particularly 10 to 50 parts by mass.

  The conductive material of the component (C) is a conductive material that does not belong to the component (B), and even if it is made of the same material physically and chemically, the particle diameter or Morse specified as the component (B) The conductive material having no hardness belongs to the component (C). The component (C) is a conductivity imparting component. For example, various metal powders such as silver, nickel and copper, carbon black, graphite, conductive metal oxide particles and the like can be used, and carbon black is preferable. These may be used alone or in combination of two or more.

  As the carbon black, those commonly used for developing rollers and the like can be used. For example, in addition to conductive carbon such as ketjen black and acetylene black, SAF, ISAF, HAF, FEF, GPF, SRF , FT, and MT.

The conductive material may be added in an amount such that the volume resistance value of the elastic layer is 10 to 10 ¹⁰ Ω · cm, but 1 to 100 parts by mass with respect to 100 parts by mass of the component (A) described above. In particular, 5 to 50 parts by mass is preferable. If the addition amount is less than 1 part by mass, the desired conductivity may not be obtained. If the addition amount exceeds 100 parts by mass, physical mixing may be difficult or the mechanical strength may be lowered. An elastic body layer may not be formed.

  The silicone rubber composition that can be suitably used for forming the elastic layer in the present invention contains various compounds as additives within a range that does not impair the object of the present invention, and as necessary. Examples of the additive include a curing agent and fine silica powder. Examples of the curing agent include a combination of a known platinum catalyst and a crosslinking agent organohydrogenpolysiloxane, and an organic peroxide catalyst.

  As the platinum-based catalyst, known ones can be used, specifically, platinum element alone, platinum compound, platinum complex, chloroplatinic acid, alcohol compound of chloroplatinic acid, aldehyde compound, ether compound, various olefins. Complex etc. are mentioned. The addition amount of the platinum-based catalyst may be an effective amount, that is, a so-called catalytic amount, and is preferably 1 to 2,000 ppm in terms of platinum group metal with respect to the organopolysiloxane of component (A).

The organohydrogenpolysiloxane may be linear, branched, or cyclic, and the degree of polymerization is preferably 300 or less, and a diorganopolysiloxane whose ends are blocked with dimethylhydrogensilyl groups, A copolymer having a terminal trimethylsiloxy group and comprising a dimethylsiloxane unit and a methylhydrogensiloxane unit, a low-viscosity fluid comprising a dimethylhydrogensiloxane unit (H (CH ₃ ) ₂ SiO _0.5 unit) and an SiO ₂ unit, 1, 3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrogen-1,3,5,7-tetramethylcyclotetra Examples thereof include siloxane and 1,5-dihydrogen-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane. The addition amount of the organohydrogenpolysiloxane is desirably used in such a ratio that the hydrogen atom directly bonded to the silicon atom is 50 to 500 mol% with respect to the alkenyl group of the organopolysiloxane of the component (A).

  Examples of organic peroxide catalysts include di-t-butyl peroxide, alkyl peroxides such as 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and aralkyl peroxides such as dicumyl peroxide. Organic peroxides such as oxides can be mentioned. The amount of the organic peroxide catalyst used is a catalytically effective amount, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of component (A).

The silica fine powder is suitable for obtaining a good elastic layer of mechanical strength, specific surface area for this purpose 10 m 2 / ^g or more, the silica fine preferably 50 to 400 m 2 / ^g It is preferable to use a powder. Examples of the silica fine powder include fumed silica (dry silica) and precipitated silica (wet silica), and fumed silica (dry silica) is preferable. In addition, as for the addition amount of this silica fine powder, 5-100 mass parts is preferable with respect to 100 mass parts of (A) component. If the amount added is less than 5 parts by mass, the amount is too small to obtain a sufficient reinforcing effect. If the amount added is more than 100 parts by mass, the workability deteriorates, and the amount is preferably 5 to 90 parts by mass, particularly preferably 10 to 50 parts by mass.

  Other additives include colorants, heat resistance improvers such as iron oxide, cerium oxide, and iron octylate, flame retardants such as halogen compounds, acid acceptors, heat conduction improvers, mold release agents, and alkoxy as necessary. Silane, dimethylsiloxane oil having a polymerization degree lower than that of component (A), silanol, for example, diphenylsilanediol, α, w-dimethylsiloxanediol, etc. Various carbon functional silanes for improving molding processability, cured and uncured various olefin elastomers that do not inhibit crosslinking, and the like may be added. When the material to be added is in the form of particles, it is desirable that the particle size be smaller than the filler of component (B).

  The silicone rubber composition can be obtained by uniformly mixing the above-described components using a rubber kneader such as a two-roll roll, a Banbury mixer, or a kneader.

  The silicone rubber composition thus prepared can be easily made into an elastic layer by heat-curing by a known method. The curing method may be any method that can apply heat necessary for crosslinking of the silicone rubber, and the molding method of the elastic body layer is not particularly limited, such as continuous crosslinking by extrusion molding, press molding, or injection molding. . In this case, the heating temperature is preferably 100 to 500 ° C., particularly 120 to 300 ° C., and the time is preferably several seconds to 1 hour, particularly 10 seconds to 30 minutes. Moreover, you may carry out secondary bridge | crosslinking on 100-200 degreeC as needed about the hardening conditions for about 1 to 20 hours.

  In the semiconductive roller according to the present invention, it is preferable that at least one coat layer is formed on the surface of the elastic layer. In particular, when an elastic body layer is produced using the silicone rubber composition, a low molecular weight silicone compound or the like may leach out from a cured product of the silicone rubber composition. And the like can be effectively prevented from adhering to the photosensitive drum and inhibiting the charged state of the photosensitive drum. Further, when the coat layer is provided on the surface of the elastic body layer, it is possible to prevent the surface of the elastic body layer from being directly scratched or worn out.

  The coat layer is preferably formed so that the pores formed on the surface of the elastic layer are not filled, and preferably the average pore diameter and number of the pores are maintained. The thickness of the coat layer is 0.1 to 50 μm, preferably 0.5 to 20 μm, more preferably 1 to 10 μm, so that the average pore diameter and number of pores are maintained within the above-described ranges. It is desirable to be selected.

  The coating layer is usually an aminosilane resin, organic fluorine compound and / or silicone compound, polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, It can be formed of alkyd resin, phenol resin, melamine resin, urea resin, silicone resin, polyvinyl butyral resin, or the like. Of these various resins, aminosilane-based resins are suitable as the resin for forming the coat layer. In addition, you may add additives, such as fillers, such as carbon, and a charge control agent, to a coat layer as needed.

  The coat layer can be formed by a coating method in which a solution containing the resin is applied to the surface of the elastic layer, a dipping method in which the elastic layer is immersed in the solution, or the like.

  When coating the surface of the elastic layer with a coat layer, a resin that activates the surface of the elastic layer by irradiating the surface of the elastic layer to be coated with ultraviolet rays, for example, an aminosilane resin Application of improves the adhesion between the elastic layer and the coat layer.

  The semiconductive roller of the present invention can be manufactured, for example, as follows. When a concrete material and a manufacturing method are illustrated, a shaft body is a column or cylinder shape first, and can be formed using a metal or a synthetic resin. A shaft formed of a non-conductive material becomes a conductive shaft if a conductive film is formed on the surface. The elastic body layer can be formed using the elastic body layer composition containing the raw material forming the rubber material and the filler. The thickness of the elastic body layer is usually 3 to 50 mm, preferably 5 to 30 mm.

  As a means for forming an elastic layer around the shaft body, in addition to the above-described continuous molding by extrusion molding, pressing, and injection molding, integral molding with the shaft body by coating, extrusion molding, injection molding, and casting. Alternatively, it is possible to adopt a method in which a shaft body is inserted into an elastic body that is previously formed into a cylindrical shape and cut to an appropriate length and bonded.

  Polishing is performed to remove the filler existing on the surface of the elastic layer in the semiconductive roller thus completed. Polishing can be performed, for example, by using a roller polishing machine, and can also be performed by increasing the degree of polishing with water-resistant paper.

  The semiconductive roller manufactured as described above is more preferable if a coating layer is provided on the surface as described above.

  The semiconductive roller thus obtained can be suitably used by being mounted on an image forming apparatus as a developing roller, for example. In particular, when the semiconductive roller according to the present invention is used as a developing roller, there is no toner supply abnormality caused by the developing roller as in the conventional image forming apparatus, there is no unevenness of printing density and fogging phenomenon, and high resolution is achieved. It can be maintained, and suitable printing can be performed over a long period of time.

(Examples 1-4, Comparative Examples 1-5)
<Preparation of shaft body, preparation of millable type silicone rubber composition>
A metal core having a diameter of 10 mm and a length of 250 mm, which is obtained by electroless nickel plating on stainless steel SUM22, was used. After washing the surface of the metal core with toluene, a silicone primer [manufactured by Shin-Etsu Chemical Co., Ltd .: trade name primer No. 16] was applied, and baked in a gear oven at 150 ° C. for 10 minutes to form a shaft.

  Next, 100 parts by mass of methyl vinyl silicone raw rubber [manufactured by Shin-Etsu Chemical Co., Ltd .: trade name KE-78VBS], 20 parts by weight of dimethyl silicone raw rubber [manufactured by Shin-Etsu Chemical Co., Ltd .: trade name KE-76VBS], carbon black [Asahi Made by Carbon Co., Ltd .: trade name Asahi Thermal] 10 parts by mass, fumed silica-based filler [made by Nippon Aerosil Co., Ltd .: trade name AEROSIL 200] 15 parts by mass, platinum catalyst [made by Shin-Etsu Chemical Co., Ltd .: trade name C-19A ] 0.5 parts by mass, (addition reaction) crosslinking agent organohydrogenpolysiloxane [manufactured by Shin-Etsu Chemical Co., Ltd .: trade name C-19B] 2.0 parts by mass, average particle diameter shown in Table 1 as a filler, and A silicone rubber composition was prepared by adding a compounding amount of calcium carbonate and kneading with a pressure kneader.

<Manufacture of rollers>
The silicone rubber composition was integrated and dispensed using a crosshead with an extruder, and was crosslinked by heating in a gear oven at 300 ° C. for 15 minutes to form a cross-linked adhesive-molded shaft having a diameter of 20 mm. In this way, after cross-linking adhesion molding to the shaft body, secondary cross-linking in a gear oven at 200 ° C. for 4 hours and polishing with a cylindrical grinder to remove the filler on the surface of the elastic layer, the diameter of the elastic layer is 16 mm, A roller base material having a length of 210 mm and a hardness of 45 (JIS A) was produced.

  Next, the outer peripheral surface of the elastic layer was subjected to ultraviolet / ozone treatment with a low-pressure mercury lamp. Thereafter, aminosilane (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name KBM603) was spray-coated to a thickness of 5 μm, and heat-cured at 150 ° C. for 30 minutes to form a coating layer to obtain a semiconductive roller.

<Surface observation of elastic body layer and coat layer>
Four semiconductive rollers of Examples 1 to 4 and Comparative Examples 1 to 4 were prepared, and the surfaces of the elastic layer and the coating layer were scanned with an electron microscope (JSM5300LV, acceleration voltage 15 kV, 1000 times, JEOL Ltd. The average pore diameter of the pores and the number of the pores were calculated from the observation image, and these are shown in Table 1.

<Image formation evaluation>
Next, four semiconductive rollers of Examples 1 to 4 and Comparative Examples 1 to 5 were prepared, and the electrophotographic printer shown in FIG. 5 (trade name: “MICROLINE 1032PS” manufactured by Oki Data Corporation, resolution) (Equivalent to 1200 dpi) as a developing roller. Note that the developer and blade attached to the electrophotographic printer were used as the developer and the developer regulating member. The average particle size of the toner was 6 μm. The image formed on the recording medium was evaluated according to the following evaluation contents. The evaluation results are shown in Table 1.
Evaluation: Excellent with no occurrence of fogging, white spots, or uneven density.
○ Any of fogging, white spots and uneven density was slightly inferior, but there was no problem in printing.
× Since any of fogging, white spots and density unevenness was inferior, printing was hindered.

FIG. 1 is a perspective view of a semiconductive roller such as a developing roller of the present invention. FIG. 2 is a perspective view of the developing roller of the present invention having a coating layer on the surface. FIG. 3 is a schematic diagram of a monochrome printer. FIG. 4 is a schematic diagram of the developing unit of the developing device. FIG. 5 is a schematic diagram showing an electrophotographic printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Semiconductive roller 2: Shaft body 3: Elastic body layer 4: Elastic body layer surface 5: Coating layer 10: Developing part of developing device 11: Developing roller 12: Developing blade 13: Photosensitive drum 14: Printing paper or transfer Belt 15: Transfer roller 16: Charging roller 17: Toner supply roller 18, 19, 20: Toner

Claims (5)

A semiconductive roller having an elastic body layer including a filler and having a semiconductivity around a shaft body and having pores on the surface, the average pore diameter of the pores being smaller than the average toner diameter A semi-conductive roller having 57 to 84% and 30 to 70 holes in 11200 μm ² .   The semiconductive roller according to claim 1, wherein the average toner diameter is 3 to 20 μm.   The semiconductive roller according to claim 1 or 2, wherein at least one coat layer is provided on the surface of the elastic layer.   The semiconductive roller according to any one of claims 1 to 3, wherein the filler is calcium carbonate.   An image forming apparatus comprising the semiconductive roller according to claim 1.

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