JP2009139924A - Transfer roll for electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer roll for an electrophotographic apparatus having superior cleanability to that of conventional rolls. <P>SOLUTION: A transfer roll for an electrophotographic apparatus 10 includes a surface layer 18 containing a roughness forming particle 22 having a particle diameter larger than a particle diameter of a toner particle 26 to be used, and surface irregularities 24 are formed by the roughness forming particles 22 on a surface of the surface layer 18. The roughness forming particle 22 is preferably harder than components of the surface layer 18 present around the roughness forming particle 22. The transfer roll 10 is suitably applied to secondary transfer of a toner image first transferred on an intermediate transfer belt to a transferring material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transfer roll for electrophotographic equipment.

  In recent years, electrophotographic apparatuses such as copying machines, printers, and facsimiles that employ an electrophotographic system have been widely used.

  In these electrophotographic apparatuses, for example, a toner image carried on a photosensitive drum is transferred to a sheet, or a toner image of each color carried on each photosensitive drum is primarily transferred to an intermediate transfer belt, A transfer roll is used in order to transfer the image from the intermediate transfer belt to a sheet at once.

  Conventionally, as a transfer roll, for example, a transfer roll in which a single foamed urethane foam layer is formed on the outer periphery of a core metal is known.

  For example, Patent Document 1 discloses a multi-layer transfer roll in which a foam layer, a resistance control layer, and a protective layer are laminated in this order on the outer periphery of a core metal.

JP 2007-147996 A

  However, conventionally known transfer rolls have the following problems.

  That is, for example, when a paper jam occurs, untransferred toner remaining without being transferred onto the paper adheres to the transfer roll surface. In addition, fog toner or the like adheres to the surface of the transfer roll.

  In an electrophotographic apparatus, toner particles adhering to a transfer roll are usually removed by a cleaning roll disposed in contact with the transfer roll.

  However, for example, in the case of the former transfer roll in which one foamed urethane layer is formed, the adhered toner particles enter the cell. Therefore, there is a problem that the cleaning property is remarkably poor. Further, the roll surface hardness increases due to clogging of the cells. Therefore, the nip width is reduced, the toner transfer rate is lowered, and image defects are likely to occur.

  On the other hand, since the latter multi-layered transfer roll has a flat roll surface, the toner particles adhering thereto are crushed by the pressure at the time of transfer and are easily fixed to the roll surface. Therefore, it is still inferior in cleaning property. Further, once the toner particles are fixed, the toner particles are fixed to the fixed toner particles one after another, so that it is difficult to recover the cleaning performance.

  As described above, the conventional transfer roll does not have sufficient cleaning properties, and therefore, there is a problem that the back surface of the paper is soiled by toner particles that cannot be removed. This type of problem becomes particularly noticeable during long-term use of electrophotographic equipment.

  The present invention has been made in view of the above circumstances, and a problem to be solved by the present invention is to provide a transfer roll for an electrophotographic apparatus, which is excellent in cleaning properties as compared with the conventional art.

  In order to solve the above-mentioned problems, the present inventors have repeated various experiments and conducted intensive studies. As a result, if the roll surface is functionally separated into (1) a portion where the toner particles do not adhere and contact the back surface of the paper and (2) a portion where the adhered toner particles are captured, the roll surface contacts the back surface of the paper. The portion to be stained is hardly contaminated with toner particles, and the trapped particles are easily removed by a cleaning roll or the like, thereby obtaining the knowledge that the cleaning property can be improved. The present invention has been made mainly based on such knowledge.

  That is, the transfer roll for an electrophotographic apparatus according to the present invention has a surface layer containing particles for forming a roughness having a particle diameter equal to or larger than the particle diameter of the toner to be used, and the surface for forming the roughness is formed on the surface of the surface layer. The gist is that surface irregularities resulting from the particles are formed.

  Here, it is preferable that the hardness of the roughness forming particles is harder than the hardness of the surface layer constituent components existing around the roughness forming particles.

  Moreover, it is preferable that the surface roughness Rz of the said surface layer exists in the range of 10-40 micrometers.

  The average particle diameter of the roughness forming particles is preferably in the range of 15 to 30 μm.

  Moreover, it is preferable that the thickness of the said surface layer exists in the range of 10-35 micrometers.

  Moreover, it is preferable that the Asker C hardness of the roll surface exists in the range of 20-40 degrees.

  Further, the roll configuration of the transfer roll includes a shaft body, a foam layer formed on the outer periphery of the shaft body, an intermediate layer formed on the outer periphery of the foam layer, and the outer layer formed on the outer periphery of the intermediate layer. It is preferable that the structure has a surface layer, or has a shaft body, a foam layer formed on the outer periphery of the shaft body, and the surface layer formed on the outer periphery of the foam layer.

  The transfer roll is preferably used for secondary transfer of the toner image primarily transferred onto the intermediate transfer belt of the electrophotographic apparatus onto a transfer material.

  The transfer roll for electrophotographic equipment according to the present invention has a surface layer containing roughness forming particles having a particle diameter equal to or larger than the toner particle size to be used, and the surface of the surface layer is caused by the roughness forming particles. Surface irregularities are formed.

  Therefore, the toner particles adhering to the roll surface almost enter the concave portion (corresponding to the portion where the roughness forming particles do not exist) and become convex portions (corresponding to the top position of the roughness forming particles) that contact the back surface of the paper. Is hard to stick. Further, the toner particles that have entered the recesses are not easily crushed by the pressure at the time of transfer, and are difficult to adhere to the surface.

  Therefore, the toner particles that have entered the recess can be easily removed by a cleaning roll or the like, and the cleaning property is excellent. Therefore, if the transfer roll is used, it becomes easy to prevent the back surface of the paper from being stained during image transfer.

  Here, when the hardness of the roughness forming particles is harder than the hardness of the surface layer constituents existing around the roughness forming particles, the convex portions of the surface layer that come into contact with the mating member are difficult to be scraped. Therefore, it becomes easy to maintain the uneven shape of the surface over a long period of time, and it becomes easy to ensure the above-mentioned cleaning properties over a long period of time.

  Moreover, when the surface roughness of the surface layer is within the above range, the above cleaning effect is easily obtained. Furthermore, it becomes difficult to damage the image carrier by scraping the surface of the intermediate transfer belt or the like when there is no paper, and it is easy to obtain a good image.

  In addition, the cleaning effect can be easily obtained when the average particle diameter of the roughness forming particles is within the above range. Furthermore, it becomes difficult to damage the image carrier by scraping the surface of the intermediate transfer belt or the like when there is no paper, and it is easy to obtain a good image.

  Further, when the thickness of the surface layer is within the above range, the balance between the effect of suppressing the wear of the surface layer and the effect of suppressing the increase in hardness of the roll surface is excellent. Therefore, it is possible to improve durability and stabilize transfer efficiency.

  Further, when the Asker C hardness of the roll surface is within the above range, a sufficient transfer nip property can be secured and the toner transfer rate can be improved.

  Further, the roll configuration of the transfer roll is configured to have a foam layer, an intermediate layer, and the surface layer in this order on the outer periphery of the shaft body, or a configuration that has a foam layer and the surface layer in order on the outer periphery of the shaft body. In such a case, the transfer nip width is widened by the flexible foam layer, and the toner transfer efficiency can be improved. In particular, when an intermediate layer is present, uneven surface unevenness due to the cells of the foamed layer can be suppressed, so that uniform surface unevenness is likely to occur.

  Further, when the electrophotographic apparatus includes an intermediate transfer belt, in the tandem system, the toner images of a plurality of colors that are primarily transferred onto the intermediate transfer belt are collectively transferred onto the paper. Therefore, the secondary transfer roll (usually used in the arrangement relationship of the intermediate transfer belt, the paper, and the secondary transfer roll) applied thereto is used in a harsh environment where toner easily adheres to the roll surface. Therefore, a high cleaning property is required.

  Therefore, when the transfer roll according to the present invention is used as a so-called secondary transfer roll, there is an advantage that it is easy to effectively suppress paper backside contamination due to the excellent cleaning effect.

  Hereinafter, a transfer roll for electrophotographic equipment (hereinafter, also referred to as “main transfer roll”) and a method for manufacturing the transfer roll (hereinafter also referred to as “main manufacturing method”) according to the present embodiment will be described. To do.

1. Main transfer roll The main transfer roll has the largest point in the structure of the outermost layer of the roll layer structure formed on the outer periphery of the shaft body. Therefore, the structure of the inner layer disposed inside the surface layer is not particularly limited. Further, the inner layer may be one layer, or two or more layers may be laminated. Hereinafter, it demonstrates more concretely using drawing.

  FIG. 1 is a circumferential cross-sectional view schematically showing an example of the present transfer roll. FIG. 2 is a circumferential sectional view schematically showing another example of the present transfer roll. In FIG. 1 and FIG. 2, the uneven state on the roll surface is omitted.

  In the transfer roll 10 shown in FIG. 1, a base layer 14 is formed along the outer peripheral surface of the shaft body 12, and an intermediate layer 16 is formed along the outer peripheral surface of the base layer 14. A surface layer 18 is formed along the surface.

  On the other hand, in the transfer roll 10 shown in FIG. 2, a base layer 14 is formed along the outer peripheral surface of the shaft body 12, and a surface layer 18 is formed along the outer periphery of the base layer 14.

  Each of the base layer and the intermediate layer may be composed of a single layer or a plurality of layers.

  The base layer can function mainly as an elastic layer having conductivity. The base layer may be a solid layer or a foam layer. Preferably, the base layer is preferably a foamed layer from the viewpoint of utilizing the flexibility to increase the transfer nip width and improve the toner transfer efficiency.

  The intermediate layer can function mainly as a resistance adjustment layer. In the present transfer roll, when the base layer is foamed, it is preferable to have an intermediate layer. By interposing the intermediate layer, it is possible to suppress variations in surface unevenness due to the cells of the foam layer, and it becomes easy to form uniform surface unevenness.

  FIG. 3 is a cross-sectional view schematically illustrating an enlarged example of the vicinity of the surface of the transfer roll illustrated in FIG. 1 or 2.

  Here, as shown in FIG. 3, in the transfer roll 10, the surface layer 18 covers the surface of the inner layer 20. The surface layer 18 contains roughness forming particles 22, and surface irregularities 24 are formed on the surface of the surface layer 18 by using bumps resulting from the roughness forming particles 22. That is, the roughness forming particles 22 are present on the convex portions 24a. The recesses 24 b are formed between the roughness forming particles 22.

  Further, in the present transfer roll 10, the roughness forming particles 22 have an average particle diameter equal to or larger than the average particle diameter of the toner particles 26 used in the electrophotographic apparatus in which the present transfer roll 10 is incorporated. This is because the toner particles 26 adhering to the roll surface are captured in the recess 24b.

  The average particle diameter of the roughness forming particles is preferably in the range of 3 to 6 times the average particle diameter of the toner particles, from the viewpoints of capturing properties of the toner particles and ease of scraping by a cleaning roll or the like. Preferably, it is in the range of 4 to 5 times.

  The average particle size of the roughness forming particles varies depending on the toner particle size to be used, but it is difficult to damage the image carrier by scraping the surface of the intermediate transfer belt or the like when there is no paper. From the viewpoint of easily obtaining an image, the upper limit is preferably 30 μm or less, more preferably 28 μm or less, and still more preferably 25 μm or less. On the other hand, the lower limit is preferably 15 μm or more, more preferably 18 μm or more, and even more preferably 20 μm or more, from the viewpoint that the amount of toner trapped in the recess is moderate and it is easy to maintain good cleaning properties. It is good to be.

  Moreover, it is preferable that the hardness of the roughness forming particles is harder than the hardness of the surface layer constituent components existing around the roughness forming particles. This is because the convex portions of the surface layer that come into contact with the mating member such as the intermediate transfer belt are difficult to be scraped, so that it becomes easy to ensure the uneven shape of the surface for a long period of time and to maintain the cleaning property for a long period of time.

  The roughness forming particles may not be exposed on the surface of the surface layer, or a part thereof may be exposed on the surface of the surface layer.

  It is preferable that the roughness forming particles are present in substantially the same plane, in other words, the particles are not stacked in the roll radial direction. This is because the top heights of the roughness forming particles become more uniform, and uniform surface irregularities are easily obtained.

  The roughness forming particles may be in contact with the inner layer in contact with the surface layer or may not be in contact. Preferably, almost all of the roughness forming particles are distributed in contact with the inner layer. This is because the difference in distance between the inner layer and the roughness-forming particles becomes more uniform, and uniform surface irregularities are easily obtained.

  In this transfer roll, the surface roughness Rz of the surface layer (10-point average roughness Rz measured according to JIS B 0601-1984) varies depending on the toner particle size to be used. The upper limit is preferably 40 μm or less, more preferably 35 μm or less, and more preferably from the viewpoint of easily obtaining a good image because it is difficult to damage the image carrier by scraping the surface of a belt or the like. Is 30 μm or less, more preferably 28 μm or less, and more preferably 25 μm or less. On the other hand, the lower limit is preferably 10 μm or more, more preferably 13 μm or more, and more preferably 15 μm or more from the viewpoint that the amount of toner trapped in the recesses is moderate and it is easy to maintain good cleaning properties. More preferably, it is more than 15 μm, more preferably 16 μm or more.

  In this transfer roll, the film thickness of the surface layer (distance from the lower surface of the surface layer to the convex portion of the surface layer) ensures sufficient transfer nip without increasing the hardness of the surface of the roll, making it easy to obtain stable transfer efficiency. From the viewpoint of becoming, the upper limit is preferably 35 μm or less, more preferably 30 μm or less, and still more preferably 25 μm or less. On the other hand, the lower limit is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more from the viewpoint of suppressing wear of the surface layer and improving durability.

  In the present transfer roll, the upper limit of the Asker C hardness of the roll surface is preferably 40 ° or less, more preferably 35 ° or less, from the viewpoint of ensuring sufficient transfer nip properties and improving the toner transfer rate. More preferably, it is 30 ° or less. On the other hand, from the viewpoint of suppressing wear of the surface layer and improving durability, the lower limit is preferably 20 ° or more, more preferably 23 ° or more, and further preferably 25 ° or more. .

The volume resistivity of the surface layer is preferably selected from the range of 10 ⁶ to 10 ⁹ Ω · cm, more preferably 10 ⁷ to 10 ⁹ Ω · cm, and still more preferably 10 ⁷ to 10 ⁸ Ω · cm. be able to.

  Specific examples of the main material for forming the surface layer include (meth) acrylic resin, fluorine resin, urethane resin, alkyd resin, polyamide resin, phenol resin, silicone resin, and resins in which these resins are modified. be able to. These may be used alone or in combination.

  As the resin material, (meth) acrylic resin, fluororesin, and the like are preferable from the viewpoint of antifouling property of toner.

  Specific examples of roughness forming particles include (meth) acrylic particles, urethane particles, urea resin particles, various resin particles such as amide particles, rubber particles, silica particles, and the like. be able to. These may be used alone or in combination.

  As the roughness forming particles, resin particles such as (meth) acrylic particles and urethane particles are preferable from the viewpoints of uniformity of particle diameter and availability.

  In the surface layer, various additives such as a conductive agent (an electronic conductive agent such as carbon black, an ionic conductive agent such as a quaternary ammonium salt), a leveling agent, a cross-linking agent, a release agent, and the like are included as necessary. Seeds or two or more species may be added.

  The structure of the surface layer has been described above. Hereinafter, each structure of a shaft body, a base layer, and an intermediate | middle layer is demonstrated.

  In the present transfer roll, any shaft body may be used as long as it has conductivity. Specific examples include solid bodies made of metal such as iron, stainless steel, and aluminum, and a cored bar made of a hollow body. Moreover, you may apply | coat an adhesive agent, a primer, etc. to the surface of a shaft body as needed. The adhesive, primer, etc. may be made conductive as necessary.

  In the present transfer roll, a rubber elastic material can be suitably used as a main material for forming the base layer. Specific examples of rubber elastic materials include ethylene-propylene-diene rubber (EPDM), hydrin rubber (ECO, CO), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), isoprene rubber, and silicone rubber. Etc. can be illustrated. These may be used alone or in combination.

  As the rubber elastic material, ethylene-propylene-diene rubber (EPDM), hydrin rubber (ECO, CO) and the like are preferable from the viewpoint of easy kneading and molding.

  The main material for forming the base layer includes a conductive agent (an electronic conductive agent such as carbon black, an ionic conductive agent such as a quaternary ammonium salt), a blowing agent (dinitrosopentamethylenetetramine, P, P′-oxybisbenzenesulfonyl hydrazide, azodirolbonamide, etc.), plasticizer (paraffin oil, naphthenic oil), vulcanizing agent (sulfur, etc.), vulcanization aid (zinc oxide, etc.), vulcanization accelerator (thiazole) 1 type or 2 types or more may be added, such as a kind, thiuram, etc.), a filler, a foam stabilizer, an active agent.

  Although the thickness of a base layer is not specifically limited, Preferably it can select from the range of 2-10 mm, More preferably, it is 4-7 mm.

The volume resistivity of the base layer is preferably selected from the range of 10 ³ to 10 ⁶ Ω · cm, more preferably 10 ³ to 10 ⁵ Ω · cm, and still more preferably 10 ³ to 10 ⁴ Ω · cm. can do.

  In the present transfer roll, a rubber elastic material can be suitably used as a main material for forming the intermediate layer. Specific examples of the rubber elastic material include acrylonitrile-butadiene rubber (nitrile rubber: NBR), hydrogenated acrylonitrile-butadiene rubber (hydrogenated nitrile rubber: H-NBR), hydrin rubber (ECO, CO), ethylene- Examples thereof include propylene-diene rubber (EPDM), acrylic rubber (ACM), and chloroprene rubber (CR). These may be used alone or in combination.

  Examples of the rubber elastic material include acrylonitrile-butadiene rubber (nitrile rubber: NBR), hydrin rubber (ECO, CO), ethylene-propylene-diene rubber, from the viewpoint of good tube extrusion moldability and easy reduction in hardness. (EPDM) and the like are preferable.

  Main materials for forming the intermediate layer include conductive agents (electronic conductive agents such as carbon black, ionic conductive agents such as quaternary ammonium salts), vulcanizing agents (such as sulfur), and vulcanization aids as necessary. Various additives such as an agent (such as zinc oxide), a vulcanization accelerator (such as thiazoles and thiurams), a filler, and an activator may be added.

  Although the thickness of an intermediate | middle layer is not specifically limited, Preferably, it can select from the range of 0.1-1 mm, More preferably, it is 0.5-0.8 mm.

The volume resistivity of the intermediate layer is preferably selected from the range of 10 ⁵ to 10 ¹¹ Ω · cm, more preferably 10 ⁶ to 10 ⁹ Ω · cm, and still more preferably 10 ⁷ to 10 ⁸ Ω · cm. can do.

2. This manufacturing method This manufacturing method is a method which can manufacture the above-mentioned transfer roll mentioned above suitably. Below, although illustrated about an example which manufactures the transfer roll which has a foam layer, an intermediate | middle layer, and a surface layer in this order on the outer periphery of a shaft, it is not necessarily limited to this manufacturing method.

  First, a cylindrical mold having a hollow columnar molding space is prepared.

  Next, a cylindrical tube serving as an intermediate layer is coaxially set in the cylindrical mold. The tube can be prepared by extruding the intermediate layer forming composition.

  Next, a foam layer forming composition to be a foam layer is attached to the outer peripheral surface of the shaft body, and this is coaxially inserted into a tube set in the cylindrical mold.

  Next, the foamed layer-forming composition is foamed by heating it at a temperature (usually within a range of about 120 ° C. to 200 ° C.) and time that is optimum for the material of the foamed layer-forming composition. Form. And the outer peripheral surface of a foam layer and the inner peripheral surface of the said tube are integrated.

  Subsequently, this is demolded to obtain a roll body in which a foam layer and an intermediate layer are laminated in this order on the outer periphery of the shaft body.

  When the base layer is a solid layer, a shaft body is coaxially installed in the hollow portion of the cylindrical mold, the base layer forming composition is injected, heated and cured, and then removed. The base layer forming composition may be extruded (extrusion method) on the surface of the shaft (casting method).

  In addition, the intermediate layer is coated with an intermediate layer forming composition on the outer periphery of the base layer using various coating methods such as a roll coating method, a dipping method, and a spray coating method, and if necessary, dried, heat-treated, It can also be formed by performing a photocuring treatment or the like.

  Next, on the outer peripheral surface of the obtained roll body, a liquid surface layer forming composition containing particles for forming the roughness is applied using various coating methods such as a roll coating method, a dipping method, and a spray coating method, If necessary, it can be dried, heat-treated at the optimal temperature and time for the surface layer forming composition material, or irradiated with active energy rays such as ultraviolet rays at the optimal irradiation intensity for the surface layer forming composition material. For example, the surface layer is formed.

  In this way, the present transfer roll can be manufactured.

  When most of the roughness forming particles contained in the surface layer are to be substantially in contact with the surface of the inner layer (intermediate layer, base layer, etc.), the roughness forming particles are placed on the surface of the roll body. After the adhesion, the surface may be covered with a surface layer-forming composition that does not contain roughness-forming particles.

  At this time, the adhesion of the particles for forming the roughness is not particularly limited, but it is preferable to use an electrostatic coating method. This is because it can be easily attached regardless of the material of the inner layer by adsorption by electrostatic force. In addition, when excessive roughness forming particles that are not in contact with the surface of the inner layer are generated, the excess roughness forming particles can be easily removed by blowing off a gas such as air. it can.

  Hereinafter, the present invention will be described in detail using examples.

1. Production of transfer roll according to examples and comparative examples (shaft body)
An iron solid cylindrical shaft body having an outer diameter of 8 mm and a length of 400 mm was prepared. The shaft body is common to Examples 1 to 3 and Comparative Examples 1 and 2.

(Preparation of foam layer forming composition)
100 parts by mass of ethylene-propylene-diene rubber (manufactured by Mitsui Chemicals, Inc., “EPT4045”), 25 parts by mass of carbon black (manufactured by Denki Kagaku Kogyo Co., Ltd., “Denka Black HS-100”), and two types of zinc oxide 5 parts by mass (Mitsui Metal Industries, Ltd.), 1 part by mass of stearic acid (manufactured by Kao Corporation, “Lunac S-30”), process oil (manufactured by Idemitsu Kosan Co., Ltd., “Diana Process PW-”) 380 ") 30 parts by mass, 15 parts by mass of dinitrosopentamethylenetetramine (foaming agent), 1 part by mass of sulfur (manufactured by Tsurumi Chemical Co., Ltd.), dibenzothiazyl disulfide (vulcanization accelerator) (Ouchi 2 parts by mass of Shinsei Chemical Industry Co., Ltd. (“Noxeller DM-P”) and tetramethylthiuram monosulfide (vulcanization accelerator) (Ouchi Shinsei Chemical Industry Co., Ltd., “Noxeller TS” ) And 1 part by weight, by kneading in a kneader to prepare a foam layer forming composition. This composition is used in Examples 1 to 4 and Comparative Example 1.

(Preparation of resistance adjustment layer forming composition)
100 parts by mass of acrylonitrile-butadiene rubber (manufactured by Nippon Zeon Co., Ltd., “Nipol DN212”), 1 part by mass of quaternary ammonium (ionic conductive agent), silica (insulating filler) (Nippon Silica Industry Co., Ltd.) Manufactured, "Nipseer ER") 30 parts by mass, 2 types of zinc oxide (Mitsui Kinzoku Kogyo Co., Ltd.) 5 parts, stearic acid (manufactured by Kao Corporation, "Lunac S-30") 1 part by mass , 1 part by mass of sulfur (manufactured by Tsurumi Chemical Co., Ltd.), 1 part by mass of dibenzothiazyl disulfide (vulcanization accelerator) (manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller DM-P”), tetra A composition for forming a resistance adjustment layer was prepared by kneading 1 part by mass of methyl thiuram monosulfide (vulcanization accelerator) (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., “Noxeller TS”) with a kneader. This composition is used in Examples 1 to 4 and Comparative Example 1.

(Preparation of surface layer forming composition <1>)
50 parts by mass of a fluorine-modified acrylate resin (Dainippon Ink Chemical Co., Ltd., “Defensor TR230K”), 50 parts by mass of a fluorinated olefin resin (Atofina Japan Co., Ltd., “Kyner 7201”), carbon black ( 100 parts by mass of Denka Black HS-100 manufactured by Denki Kagaku Kogyo Co., Ltd. and acrylic particles (roughness forming particles) (manufactured by Soken Chemical Co., Ltd., “Chemisnow MX1500”, average particle size: 15 μm) 30 parts by mass and 100 parts by mass of MEK were dispersed, mixed, and stirred to prepare a surface layer forming composition <1>. This composition is used in Example 1.

(Preparation of surface layer forming composition <2>)
In the preparation of the surface layer forming composition <1>, other than the use of acrylic particles having different average particle sizes (“Kemisnow MX2000”, average particle size: 20 μm) as the roughness forming particles. In the same manner, a surface layer forming composition <2> was prepared. This composition is used in Example 2.

(Preparation of surface layer forming composition <3>)
In the preparation of the surface layer forming composition <1>, other than the use of acrylic particles having different average particle diameters (“Kemisnow MX3000”, average particle diameter: 30 μm, manufactured by Soken Chemical Co., Ltd.) as the roughness forming particles. In the same manner, a surface layer forming composition <3> was prepared. This composition is used in Example 3.

(Preparation of surface layer forming composition <4>)
In the preparation of the surface layer forming composition <1>, 50 parts by mass of acrylic particles having different average particle diameters (“Kemisnow MX3000”, average particle diameter: 30 μm, manufactured by Soken Chemical Co., Ltd.) are used as the roughness forming particles. A surface layer forming composition <4> was prepared in the same manner as described above. This composition is used in Example 4.

(Preparation of surface layer forming composition <5>)
In preparing the surface layer forming composition <1>, a surface layer forming composition <5> was prepared in the same manner except that the roughness forming particles were not used. This composition is used in Comparative Example 2.

  Using the roll constituent materials prepared as described above, transfer rolls according to Examples and Comparative Examples were produced by the following procedure.

(Example 1)
A tube (outer diameter 24 mm, thickness 0.6 mm, length 342 mm) was formed by extruding the prepared resistance adjusting layer forming composition.

  The tube was then set coaxially in a cylindrical mold. Next, the foam layer-forming composition was adhered to the outer peripheral surface of the shaft, and this was coaxially inserted into a tube set in the cylindrical mold.

  Next, this is heated at 160 ° C. for 40 minutes to foam the foam layer forming composition to form a conductive foam layer. The outer peripheral surface and the inner peripheral surface of the tube (resistance adjusting layer) are formed. Integrated.

  Next, this was removed from the mold, and a roll body (outer diameter 24 mm) in which a foam layer (thickness 6 mm, length 342 mm) and a resistance adjustment layer (thickness 0.6 mm, length 342 mm) were laminated in this order on the outer periphery of the shaft body. Got.

  Next, the liquid surface layer forming composition <1> is applied to the outer peripheral surface of the roll body by using a roll coating method, and then cured by heating at 120 ° C. for 30 minutes to obtain a surface layer (thickness of 0. 0). 05 mm).

  As described above, the surface layer containing the foam layer, the resistance adjusting layer, and the acrylic particles (roughness forming particles) is laminated in this order on the outer periphery of the shaft body, and the surface of the surface layer has surface irregularities due to the acrylic particles. A transfer roll according to Example 1 was produced.

(Example 2)
In the production of the transfer roll according to Example 1, the transfer roll according to Example 2 was produced in the same manner except that the surface layer forming composition <2> was used instead of the surface layer forming composition <1>. did.

  The transfer roll according to Example 2 has a foam layer, a resistance adjusting layer, and a surface layer containing acrylic particles (roughness forming particles) laminated in this order on the outer periphery of the shaft body. It has surface irregularities due to acrylic particles.

(Example 3)
In the production of the transfer roll according to Example 1, the transfer roll according to Example 3 was produced in the same manner except that the surface layer forming composition <3> was used instead of the surface layer forming composition <1>. did.

  The transfer roll according to Example 3 has a foam layer, a resistance adjustment layer, and a surface layer containing acrylic particles (roughness forming particles) laminated in this order on the outer periphery of the shaft body. It has surface irregularities due to acrylic particles.

Example 4
In the production of the transfer roll according to Example 1, the transfer roll according to Example 4 was produced in the same manner except that the surface layer forming composition <4> was used instead of the surface layer forming composition <1>. did.

  Note that the transfer roll according to Example 4 has a foam layer, a resistance adjustment layer, and a surface layer containing acrylic particles (roughness forming particles) laminated in this order on the outer periphery of the shaft body. It has surface irregularities due to acrylic particles.

(Comparative Example 1)
According to Comparative Example 1, a foam layer (average cell diameter: 50 to 100 μm) made of conductive urethane is formed on the outer periphery of the prepared shaft body and polished to a predetermined outer diameter (φ24 mm). A transfer roll was prepared.

(Comparative Example 2)
In the production of the transfer roll according to Example 1, the transfer roll according to Comparative Example 2 was produced in the same manner except that the surface layer forming composition <5> was used instead of the surface layer forming composition <1>. did.

  In the transfer roll according to Comparative Example 2, the foam layer, the resistance adjusting layer, and the surface layer not including the roughness forming particles are laminated in this order on the outer periphery of the shaft body.

2. Measurement of roll physical properties and roll evaluation For each of the obtained transfer rolls, measurement of roll surface roughness, evaluation of cleaning properties and image quality were performed as follows.

(Roll surface roughness)
For each transfer roll, the ten-point average roughness Rz was measured using a surface roughness measuring device (manufactured by Tokyo Seimitsu Co., Ltd., “SURFCOM 1400D”) in accordance with JIS B 0601-1982.

  The ten points of average roughness Rz are measured at three locations (three equal parts) in the roll circumferential direction for the left end portion, central portion, and right end portion in the roll axis direction, that is, a total of nine locations.

(Cleanability)
Each transfer roll was incorporated as a secondary transfer roll in a secondary transfer unit portion of a commercially available electrophotographic apparatus (use toner particle size: 5 μm), and an actual machine durability test was performed on the condition of the transfer roll surface.

  The secondary transfer unit portion of the electrophotographic apparatus is equipped with a cleaning roll device in which conductive nylon or the like is implanted as a mechanism for cleaning dirt on the secondary transfer roll.

  In this evaluation, after printing 100,000 sheets of a photo / character mixed chart image (image density 5%, A4) in A4 size, how much toner remains on the surface of the secondary transfer roll The cleaning property was evaluated by visually confirming that there was no contamination.

  If there is almost no toner remaining on the roll surface and there is no stain on the back side of the paper, the cleaning performance is extremely excellent. ◎ Some toner remains, but there is no stain on the back side of the paper, and there is no quality problem. The case was judged as “good” because of its excellent cleaning property. On the other hand, when the toner adhered to the roll surface and the stain was clearly confirmed on the back side of the paper, it was judged as “poor” because the cleaning property was poor.

(Image confirmation)
Similarly to the evaluation of the cleaning property, each transfer roll is incorporated as a secondary transfer roll in the secondary transfer unit of the electrophotographic apparatus, and a halftone image (image density 30%, A4) is obtained in A4 size. 100,000 sheets were printed. Then, both the initial image quality and the image quality after durability were confirmed, and the image quality was confirmed for white spots.

  When the number of white spots was 0, the image quality was judged to be very good, and when the number of white spots was 1 or more and less than 3, the image quality was judged to be good. On the other hand, when the number of white spots was 3 or more, the image quality was judged to be poor as x.

  Table 1 summarizes each roll configuration, roll evaluation results, and the like.

  A relative comparison of Table 1 shows the following. That is, the transfer roll according to Comparative Example 1 had extremely poor cleaning properties because the toner particles entered the foamed cells. Also, the image quality after endurance was bad. This is presumed that the toner entered and accumulated in the cells as clogging occurred as the durability increased, and the roll surface hardness increased, the nip width decreased, and the toner transfer rate decreased, leading to image defects. Is done.

  In the transfer roll according to Comparative Example 2, the toner adhered to the roll surface and the cleaning property was poor. This is presumably due to the fact that the surface of the roll is relatively flat, so that the adhered toner particles were easily crushed by the pressure during transfer.

  On the other hand, it can be confirmed that the transfer rolls according to Examples 1 to 4 have excellent cleaning properties over a long period of time with respect to the transfer rolls according to these comparative examples, and thereby can effectively prevent the paper back surface stains. It was.

  In addition, it was confirmed that the transfer rolls according to Examples 1 to 4 were excellent in toner transferability by having sufficient transfer nip properties without causing damage to the surface of the intermediate transfer belt and causing image defects. .

  The embodiments and examples of the present invention have been described above, but the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. is there.

It is the circumferential direction sectional view showing typically an example of the transfer roll concerning this embodiment. It is the circumferential direction sectional view which showed typically the other example of the transfer roll concerning this embodiment. FIG. 3 is a cross-sectional view schematically illustrating an enlarged example of the vicinity of the surface of the transfer roll illustrated in FIGS. 1 and 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transfer roll 12 Shaft body 14 Base layer 16 Intermediate layer 18 Surface layer 20 Inner layer 22 Roughness formation particle 24 Surface unevenness 24a Convex part 24b Concave part 26 Toner particle

Claims (8)

Having a surface layer containing roughness forming particles having a particle size equal to or greater than the toner particle size used;
A transfer roll for an electrophotographic apparatus, wherein surface irregularities resulting from the roughness forming particles are formed on the surface of the surface layer.   2. The transfer roll for an electrophotographic apparatus according to claim 1, wherein the hardness of the roughness forming particles is harder than the hardness of a surface layer constituent component existing around the roughness forming particles.   The transfer roll for electrophotographic equipment according to claim 1 or 2, wherein the surface roughness Rz of the surface layer is in the range of 10 to 40 µm.   The transfer roll for electrophotographic equipment according to any one of claims 1 to 3, wherein the average particle diameter of the roughness forming particles is in the range of 15 to 30 µm.   5. The transfer roll for an electrophotographic apparatus according to claim 1, wherein a thickness of the surface layer is in a range of 10 to 35 μm.   The transfer roll for electrophotographic equipment according to any one of claims 1 to 5, wherein the Asker C hardness of the roll surface is in the range of 20 to 40 °. A shaft body, a foam layer formed on the outer periphery of the shaft body, an intermediate layer formed on the outer periphery of the foam layer, and the surface layer formed on the outer periphery of the intermediate layer, or
The electrophotographic apparatus according to claim 1, further comprising: a shaft body, a foam layer formed on an outer periphery of the shaft body, and the surface layer formed on an outer periphery of the foam layer. Transfer roll. The electrophotographic apparatus includes an intermediate transfer belt,
8. The transfer roll for an electrophotographic apparatus according to claim 1, wherein the transfer roll is used for secondary transfer of the toner image primarily transferred onto the intermediate transfer belt onto a transfer material.

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