JP5314336B2 - Transfer roll for electrophotographic equipment and manufacturing method thereof - Google Patents

Description

  The present invention relates to a transfer roll for electrophotographic equipment and a method for producing the same.

  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, Patent Document 1 discloses a shaft body, a foam layer formed on the outer periphery of the shaft body, a resistance adjustment layer formed on the outer periphery of the foam layer, and an outer periphery of the resistance adjustment layer. A transfer roll having a formed protective layer is disclosed.

  In the same document, as a method for manufacturing the transfer roll, a cylindrical tube serving as a resistance adjusting layer and a shaft body on which a foam material is attached are coaxially formed in a mold having a hollow cylindrical molding space. In this state, a foamed material is foamed to form a foamed layer, and then a protective layer is formed on the outer periphery of the resistance adjusting layer.

JP 2007-147996 A

  However, conventionally known transfer rolls have the following problems.

  For example, in the fields of POD (Print On Demand) machines and MFP (Multifunction Printer) high-end machines for the light printing market, demands for higher image quality are increasing year by year. In the transfer roll used for the toner transfer site, uneven electrical resistance of the roll has a great influence on the image quality level. For this reason, transfer rolls applied to the above-mentioned models and the like are required to have electrical uniformity at an increasingly severe level.

  However, as in the manufacturing method described above, when a tube-shaped resistance adjustment layer is installed in the mold and foaming is performed in the tube, a relatively smooth skin layer is not formed on the surface of the foam layer, Rough cells may occur near the interface between the foam layer and the resistance adjustment layer (cell roughness). In some cases, the foam layer and the inner surface of the tube do not adhere to each other, and a void defect may occur.

  This type of void due to cell roughness, void defects, or the like locally changes the electrical resistance in that portion, which causes uneven electrical resistance.

  Therefore, the conventional transfer roll has a problem that image defects are likely to occur due to uneven electrical resistance.

  In recent years, high durability has been demanded particularly for transfer rolls that are applied to the above-mentioned models and the like. Usually, the transfer roll is pressed against the mating member with a relatively high pressure. Therefore, when the interlayer adhesion between the foam layer and the resistance adjustment layer is low, delamination tends to occur.

  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 that can suppress image defects caused by uneven electrical resistance and achieve high durability. It is to provide.

  In order to solve the above problems, an electrophotographic apparatus transfer roll according to the present invention includes a shaft body, a foam layer formed on the outer periphery of the shaft body, an electrode layer formed on the outer periphery of the foam layer, and At least a resistance adjustment layer formed of a tube body formed on the outer periphery of the electrode layer, and the foam layer, the electrode layer, and the resistance adjustment layer all have rubber elasticity, and the volume of the electrode layer The gist is that the resistivity is equal to or less than the volume resistivity of the foam layer.

  Here, the polymer mainly constituting the electrode layer is preferably a polymer mainly constituting the foam layer and / or a polymer similar to the polymer mainly constituting the resistance adjusting layer.

  The polymer mainly constituting the foam layer is one or more selected from ethylene-propylene-diene rubber, hydrin rubber, and urethane rubber, and the polymer mainly constituting the electrode layer is ethylene. -One or more selected from propylene-diene rubber, hydrin rubber, and nitrile rubber, and the polymer mainly constituting the resistance adjusting layer is selected from ethylene-propylene-diene rubber, hydrin rubber, and nitrile rubber. It is preferable that it is 1 type, or 2 or more types.

The volume resistivity of the electrode layer is preferably in the range of 1 × 10 ³ to 1 × 10 ⁶ Ω · cm.

  Moreover, it is preferable that the thickness of the said electrode layer exists in the range of 5-100 micrometers.

  A surface layer is preferably formed on the outer periphery of the resistance adjustment layer.

  The method for producing a transfer roll according to the present invention includes a step of preparing a tube body to be a resistance adjusting layer, the electrode layer forming composition being adhered to the inner peripheral surface thereof, and the above preparation in a roll molding die. The tube body and the shaft body with the foam layer forming composition attached to the outer peripheral surface are coaxially installed, the foam layer forming composition is foamed, and the formed foam layer and the electrode And a step of integrating the layers.

  The transfer roll for electrophotographic equipment according to the present invention includes at least a shaft body, a foam layer, an electrode layer, and a resistance adjustment layer made of a tube body, and the foam layer, the electrode layer, and the resistance adjustment layer are any Also has rubber elasticity, and the volume resistivity of the electrode layer is less than or equal to the volume resistivity of the foamed layer.

  For this reason, even when a void is generated between the foamed layer and the resistance adjusting layer due to cell roughness, void defects, or the like on the surface of the foamed layer, electrons easily flow due to the presence of the electrode layer. Therefore, the electric resistance unevenness due to the gap is alleviated, and it is possible to suppress image defects caused by the electric resistance unevenness.

  The electrode layer has rubber elasticity like the foam layer and the resistance adjustment layer. Therefore, it is easy to follow the deformation due to pressure, and it is easy to ensure interlayer adhesion, and high durability is easily realized.

  Here, when the polymer mainly constituting the electrode layer is a polymer mainly constituting the foam layer and / or a polymer similar to the polymer mainly constituting the resistance adjusting layer, the foam layer and / or Since the adhesion between the resistance adjustment layer and the electrode layer is further improved, the durability is easily improved.

  Moreover, when the polymer which mainly comprises a foam layer, an electrode layer, and a resistance adjustment layer is selected from the above-mentioned polymer, it becomes easy to obtain moderate roll hardness.

  Moreover, when the volume resistivity of the electrode layer is within the above range, durability due to energization is easily improved.

  Moreover, when the thickness of an electrode layer exists in the said range, it is excellent in the balance of the current collection effect and roll hardness by an electrode layer.

  Further, when the surface layer is formed on the outer periphery of the resistance adjustment layer, it becomes easy to improve the toner adhesion resistance.

  Since the manufacturing method of the transfer roll for electrophotographic equipment according to the present invention includes the above-described steps, the transfer roll can be preferably manufactured.

  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 FIG. 1 is a circumferential sectional view schematically showing an example of the main transfer roll. A transfer roll 10 shown in FIG. 1 includes a shaft body 12, a foam layer 14 formed along the outer peripheral surface of the shaft body 12, an electrode layer 16 formed along the outer peripheral surface of the foam layer 14, and an electrode layer. 16 and at least a resistance adjusting layer 18 formed along the outer peripheral surface.

  FIG. 2 is a circumferential sectional view schematically showing another example of the present transfer roll. In the transfer roll 10 shown in FIG. 2, a surface layer 20 is further formed along the outer peripheral surface of the resistance adjustment layer 18.

  The transfer roll preferably has a surface layer 20 as shown in FIG. This is because it becomes easy to improve the toner adhesion resistance.

  In the present transfer roll, each of the foam layer, the electrode layer, the resistance adjustment layer, and the surface layer may be composed of a single layer or a plurality of layers. Preferably, from the viewpoint of improving productivity by simplifying the roll layer configuration, each layer is preferably composed of a single layer.

  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.

  Here, in this transfer roll, the foam layer, the electrode layer, and the resistance adjustment layer all have rubber elasticity. Since each of these layers has rubber elasticity, the followability to deformation due to pressure is improved, the interlayer adhesion is easily secured, and high durability is easily realized. In addition, it is easy to impart a suitable roll hardness to the transfer roll, and it is easy to increase the transfer nip width by utilizing flexibility and improve the toner transfer efficiency.

  These foam layer, electrode layer, and resistance adjustment layer are formed mainly using a rubber elastic material. Hereinafter, each of these layers will be described.

  In the present transfer roll, as the polymer mainly constituting the foam layer, specifically, for example, ethylene-propylene-diene rubber (EPDM), hydrin rubber (ECO, CO), urethane rubber, styrene-butadiene rubber (SBR), Nitrile rubber (NBR), isoprene rubber, silicone rubber and the like can be exemplified. These may be used alone or in combination.

  As the polymer mainly constituting the foam layer, ethylene-propylene-diene rubber (EPDM), hydrin rubber (ECO, CO), urethane rubber and the like are preferable from the viewpoint of easy kneading and molding.

  Specific examples of the foaming agent for foaming the polymer mainly constituting the foamed layer include, for example, dinitrosopentamethylenetetramine, P, P′-oxybisbenzenesulfonylhydrazide, and azodirolbonamide. Can do. These may be contained alone or in combination of two or more.

  For the polymer mainly constituting the foamed layer, if necessary, a conductive agent (electronic conductive agent such as carbon black, ionic conductive agent such as quaternary ammonium salt), plasticizer (paraffin oil, naphthenic oil), 1 or 2 of various additives such as vulcanizing agents (such as sulfur), vulcanizing aids (such as zinc oxide), vulcanization accelerators (such as thiazoles, thiurams), fillers, foam stabilizers, activators, etc. More than seeds may be added.

  The thickness of the foam layer is not particularly limited, but is preferably selected from the range of 2 to 10 mm, more preferably 4 to 7 mm, from the viewpoint that a sufficient nip width is easily obtained. Can do.

  In the present transfer roll, as the polymer mainly constituting the electrode layer, specifically, for example, ethylene-propylene-diene rubber (EPDM), hydrin rubber (ECO, CO), nitrile rubber (NBR), hydrogenated nitrile rubber, etc. Can be illustrated. These may be used alone or in combination.

  From the standpoint of flexibility and ease of lowering electrical resistance, the polymer mainly constituting the electrode layer includes ethylene-propylene-diene rubber (EPDM), hydrin rubber (ECO, CO), nitrile rubber (NBR), and the like. preferable.

  For the polymer that mainly constitutes the electrode layer, a conductive agent (an electronic conductive agent such as carbon black, an ionic conductive agent such as a quaternary ammonium salt), a plasticizer (paraffin oil, naphthenic oil), 1 or 2 of various additives such as vulcanizing agents (such as sulfur), vulcanizing aids (such as zinc oxide), vulcanization accelerators (such as thiazoles, thiurams), fillers, foam stabilizers, activators, etc. More than seeds may be added.

  The thickness of the electrode layer is preferably in the range of 5 to 100 μm, more preferably 7 to 20 μm, and still more preferably 10 to 15 μm from the viewpoint of excellent balance between the current collecting effect and roll hardness by the electrode layer. Good to be inside.

  In the present transfer roll, the resistance adjusting layer is a layer made of a tube body. Specific examples of the polymer mainly constituting the resistance adjusting layer include, for example, ethylene-propylene-diene rubber (EPDM), hydrin rubber (ECO, CO), nitrile rubber (NBR), acrylic rubber (ACM), chloroprene rubber ( CR) and the like. These may be used alone or in combination.

  As the polymer mainly constituting the resistance adjustment layer, ethylene-propylene-diene rubber (EPDM), hydrin rubber (ECO, CO), nitrile rubber (NBR) and the like are flexible and easy to lower the electric resistance. preferable.

  The polymer mainly constituting the resistance adjusting layer may include a conductive agent (an electronic conductive agent such as carbon black, an ionic conductive agent such as a quaternary ammonium salt), a vulcanizing agent (such as sulfur), a vulcanizing agent, if necessary. One or more additives such as a sulfur assistant (such as zinc oxide), a vulcanization accelerator (such as thiazoles and thiurams), a filler, and an activator may be added.

  The thickness of the resistance adjusting layer is 0.1 to 1 mm, more preferably 0 from the viewpoint of ensuring sufficient transfer nip property without increasing the hardness of the roll and making it easy to obtain stable transfer efficiency. It can be selected from the range of 0.5 to 0.8 mm.

  In the present transfer roll, as the polymer mainly constituting the surface layer, specifically, for example, (meth) acrylic resin, fluorine resin, urethane resin, alkyd resin, polyamide resin, phenol resin, silicone resin, and these resins are modified. An example of such a resin can be given. These may be used alone or in combination.

  As the polymer mainly constituting the surface layer, a (meth) acrylic resin, a fluororesin or the like is preferable from the viewpoint of toner adhesion resistance and the like.

  In order to roughen the surface of the surface layer, the polymer mainly constituting the surface layer, if necessary, various resin particles such as (meth) acrylic particles, urethane particles, urea resin particles, amide particles, One kind or two or more kinds of roughness forming particles such as rubber particles and silica particles may be added.

  As the roughness forming particles, resin particles such as (meth) acrylic particles and urethane particles can be suitably used from the viewpoint of uniformity of particle diameter, availability, and the like.

  In addition, the polymer mainly constituting the surface layer may include 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 crosslinking agent, a release agent, as necessary. Various additives such as molds may be added alone or in combination.

  In the present transfer roll, the polymer mainly constituting the electrode layer is preferably a polymer similar to the polymer mainly constituting the foamed layer and / or the polymer mainly constituting the resistance adjusting layer. In such a case, the adhesion between the foam layer and / or the resistance adjusting layer and the electrode layer is further improved, so that the durability is easily improved.

  Here, in this transfer roll, the volume resistivity ρ1 of the electrode layer is set to be equal to or less than the volume resistivity ρ2 of the foam layer (ρ1 ≦ ρ2).

  When the volume resistivity of both layers satisfies the above relationship, electrons flow through the electrode layer even when there are voids between the foam layer and the resistance adjustment layer due to cell roughness or void defects on the surface of the foam layer. It becomes easy. Therefore, the electric resistance unevenness due to the gap is alleviated, and image defects caused by the electric resistance unevenness can be suppressed.

The volume resistivity ρ1 of the electrode layer is preferably 1 × 10 ³ to 1 × 10 ⁶ Ω · cm, and more preferably 1 × 10 ³ to 1 × 10 ⁵ Ω, from the viewpoint of improving durability due to energization. · Cm, more preferably in the range of 1 × 10 ³ to 1 × 10 ⁴ Ω · cm.

The volume resistivity ρ2 of the foam layer, from the viewpoint of improvement of durability due to energization, ^{preferably, 1 × 10 3 ~1 × 10} 6 Ω · cm, more preferably, 1 × ¹⁰ 3 ~1 × ^{10 5} Ω · cm, more preferably 1 × 10 ³ to 1 × 10 ⁴ Ω · cm.

The volume resistivity of the resistance adjusting layer and the surface layer is not particularly limited. The volume resistivity of the resistance adjusting layer is preferably 1 × 10 ⁵ to 1 × 10 ¹¹ Ω · cm, and more preferably 1 × 10 ⁶ to 1 × 10 ⁹ from the viewpoint that a good image is easily obtained. It can be selected from the range of Ω · cm, more preferably 1 × 10 ⁷ to 1 × 10 ⁸ Ω · cm. The volume resistivity of the surface layer, from the viewpoint of good image can be easily obtained, ^{preferably, 1 × 10 6 ~1 × 10} 9 Ω · cm, more ^{preferably, 1 × 10 7 ~1 × 10} 9 Ω · cm, more preferably, can be selected from the range of 1 × 10 ⁷ to 1 × 10 ⁸ Ω · cm.

  The volume resistivity can be adjusted by changing the ratio of the conductive agent contained in each layer.

  Moreover, the said volume resistivity can be calculated | required by forming an electrode in each sheet-like sample produced from each layer forming composition, and applying 100V so that it may describe in the below-mentioned Example.

  The upper limit of the roll hardness of the present transfer roll is asker C hardness, 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. Further, from the viewpoint of suppressing wear of the surface layer and improving durability, the lower limit is Asker C hardness, preferably 20 ° or more, more preferably 23 ° or more, and further preferably 25 °. It is good to be above.

2. This manufacturing method This manufacturing method is a method which can manufacture the above-mentioned transfer roll mentioned above suitably. This manufacturing method has at least the following steps (1) to (3).

  Step (1) is a step of preparing a tube body serving as a resistance adjustment layer, in which the electrode layer forming composition is adhered to the inner peripheral surface thereof.

  Specifically, first, a tube body having a predetermined thickness is formed by extruding the composition for forming a resistance adjusting layer.

  Thereafter, using various coating methods such as a spray coating method and a dipping method, the liquid electrode layer forming composition is adhered to the inner peripheral surface of the molded tube body with a predetermined thickness and dried.

  Thereby, the tube body which made the electrode layer formation composition adhere to the internal peripheral surface can be prepared.

  Step (2) is a step of coaxially installing the prepared tube body and the shaft body having the foam layer forming composition attached to the outer peripheral surface thereof in a roll molding die.

  Specifically, first, a roll molding die such as a cylindrical die having a hollow columnar molding space is prepared. Next, the prepared tube body is coaxially set in the roll molding die. Next, a shaft body in which the foam layer forming composition is attached to the outer peripheral surface may be coaxially inserted into the tube set in the roll molding die.

  In the above, the case where the tube body and the shaft body are sequentially set in the roll molding die is illustrated. However, for example, the shaft body and the tube body are sequentially set in the roll molding die. Alternatively, the tube body and the shaft body may be set simultaneously in the roll molding die.

  A foamed layer is formed between the surface of the composition for forming an unfoamed foam layer attached to the outer periphery of the shaft body and the surface of the composition for forming an electrode layer attached to the inner peripheral surface of the tube body by passing through the above steps. Forming space is formed.

  Step (3) is a step of foaming the foam layer forming composition and integrating the formed foam layer and the electrode layer.

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

  Thereafter, when the mold is removed, a transfer roll in which a foam layer, an electrode layer, and a resistance adjustment layer are laminated in this order on the outer periphery of the shaft body is obtained.

  When a surface layer is further formed on the outer peripheral surface of the resistance adjustment layer, a liquid surface layer forming composition is applied using various coating methods such as a roll coating method, a dipping method, and a spray coating method, and then as necessary. Or heat treatment at an optimal temperature and time for the material for the surface layer forming composition, or irradiation with active energy rays such as ultraviolet rays at an optimal irradiation intensity for the material for the surface layer forming composition. For example, a surface layer can be formed.

  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. In addition, this shaft body is used in common with an Example and a comparative example.

(Preparation of foam layer forming composition)
100 parts by mass of ethylene-propylene-diene rubber (“EPT4045” manufactured by Mitsui Chemicals, Inc.) and a predetermined ratio of carbon black (“Denka Black HS-100” manufactured by Denki Kagaku Kogyo Co., Ltd.) shown in Table 1 , 2 parts of zinc oxide (made by Mitsui Kinzoku Co., Ltd.), 1 part by weight of stearic acid (manufactured by Kao Corporation, “Lunac S-30”), process oil (made by Idemitsu Kosan Co., Ltd.) "Diana Process PW-380") 30 parts by mass, dinitrosopentamethylenetetramine (foaming agent) 15 parts by mass, sulfur (manufactured by Tsurumi Chemical Co., Ltd.) 1 part by mass, dibenzothiazyl disulfide (vulcanization acceleration) Agent) (Ouchi Shinsei Chemical Industry Co., Ltd., “Noxeller DM-P”) 2 parts by mass and tetramethylthiuram monosulfide (vulcanization accelerator) (Ouchi Shinsei Chemical Co., Ltd. A cellar TS ") 1 part by weight, by kneading in a kneader, to prepare each foam layer forming composition of EPDM system. Each of these compositions is used in each example and each comparative example.

(Preparation of electrode layer forming composition)
100 parts by mass of ethylene-propylene-diene rubber (manufactured by Mitsui Chemicals, Inc., “EPT4045”), a predetermined proportion of carbon black (Ketjen Black International, “Ketjen Black EC”) shown in Table 1, and oxidation 2 parts of zinc (Mitsui Kinzoku Kogyo Co., Ltd.) 5 parts by mass, stearic acid (Kao Co., Ltd., “Lunac S-30”) 0.5 parts by mass, sulfur (Tsurumi Chemical Co., Ltd.) 1 part by mass, 2 parts by mass of dibenzothiazyl disulfide (vulcanization accelerator) (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., “Noxeller DM-P”), tetramethylthiuram monosulfide (vulcanization accelerator) ( Each composition for forming an electrode layer of an EPDM system was prepared by kneading 1 part by mass of “Noxeller TS” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. with a kneader. These compositions are used in Examples 1 to 6 and Comparative Examples 2 and 3.

  Further, an NBR-based electrode layer forming composition was prepared in the same manner except that nitrile rubber (manufactured by Nippon Zeon Co., Ltd., “Nipol DN212”) was used in place of the ethylene-propylene-diene rubber. This composition is used in Example 7.

  In addition, a PA-based electrode layer forming composition was prepared in the same manner except that a polyamide resin (manufactured by Nagase ChemteX Corporation, “Tresin”) was used instead of the ethylene-propylene-diene rubber. This composition is used in Comparative Example 4.

(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. In addition, this composition is used in common with an Example and a comparative example.

(Preparation of surface layer forming composition)
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 ( A composition for forming a surface layer was prepared by dispersing, mixing, and stirring 100 parts by mass of Denka Black HS-100 manufactured by Denki Kagaku Kogyo Co., Ltd. and 100 parts by mass of MEK. In addition, this composition is used in common with an Example and a comparative example.

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

(Examples 1-7, Comparative Examples 2-4)
First, a tube body (outer diameter 24 mm, thickness 0.6 mm) was formed by extruding the prepared composition for forming a resistance adjusting layer. Next, each electrode layer forming composition was dissolved in an organic solvent (toluene, but methanol only in the case of PA of Comparative Example 4) to prepare each electrode layer forming coating solution. Next, each of the prepared electrode layer forming coating solutions was applied to the inner peripheral surface of each tube body by a spray method and dried. Thus, each tube body was prepared in which each electrode layer forming composition having the thickness shown in Table 1 was attached to the inner peripheral surface.

  Next, each tube body prepared above was set coaxially in a cylindrical roll molding die.

  Next, each shaft body in which each foam layer forming composition was directly adhered to the outer peripheral surface by extrusion was set coaxially in each tube body set in each mold.

  Next, this was heated at 160 ° C. for 40 minutes to foam each foamed layer forming composition, and each foamed layer and each electrode layer thus formed were integrated.

  Subsequently, this was removed from the mold, and each foam layer (all EPDM type) having the thicknesses shown in Table 1 on the outer periphery of the shaft body, each electrode layer (Examples 1 to 6 were EPDM type, Example 7 was NBR) System) and each resistance adjusting layer (all NBR systems) were obtained in this order.

  Subsequently, after apply | coating the liquid surface layer forming composition to the outer peripheral surface of each obtained roll body using the roll coat method, it hardens | cures by heating for 30 minutes at 120 degreeC, and each surface layer (thickness 0. 05 mm).

  As described above, the transfer roll according to Examples 1 to 7 and the transfer roll according to Comparative Examples 2 to 4 in which the foam layer, the electrode layer, the resistance adjustment layer including the tube body, and the surface layer are laminated in this order on the outer periphery of the shaft body. Produced.

  In addition to the roll samples prepared as described above, a part of the unfoamed foam layer forming composition attached to the outer periphery of the shaft body was cut out (diameter 5 to 8 mm, depth 1 mm). Through the same process, an image evaluation roll sample in which a gap was formed between the tube body and the foamed layer was also produced.

(Comparative Example 1)
In the production of the transfer roll according to Example 1, the transfer roll according to Comparative Example 1 and the image evaluation roll sample (gap) were similarly used except that the electrode layer forming composition was not attached to the inner peripheral surface of the tube body. Formed product). In these rolls, a foam layer, a resistance adjustment layer made of a tube body, and a surface layer are laminated in this order on the outer periphery of the shaft body, and do not have an electrode layer.

2. Measurement of Volume Resistivity Each foamed layer forming composition prepared above is sandwiched between spacers (3 mm thickness) and left for 1 hour or longer to form a sheet of 3 mm thickness, and then foamed at 160 ° C. for 45 minutes. -Vulcanized. This produced each sheet-like sample which measures the volume resistivity of each foam layer.

  Thereafter, a 1 cm square electrode was applied to the front and back surfaces of each obtained sheet-like sample with a silver paste, and after drying, the thickness (L: mm) was measured. Subsequently, the resistance value (R: Ω) when 100 V was applied to the front and back electrodes was measured. The volume resistivity was calculated from volume resistivity ρv (Ω · cm) = (R / L) × 10.

  Also, each of the electrode layer forming compositions prepared above is dissolved in an organic solvent to prepare each coating solution, and each coating solution is uniformly applied at a thickness of 1 mm on one side of a PET film having conductive films formed on the front and back sides. It was applied and dried. Next, heat treatment was performed at 160 ° C. for 45 minutes for vulcanization. This produced each sheet-like sample which measures the volume resistivity of each electrode layer.

  Thereafter, a 1 cm square electrode was applied to the upper surface of the obtained sheet-like sample with a silver paste, and after drying, the thickness (L: mm) was measured. Next, the resistance value (R: Ω) when 100 V was applied to the electrode on the coating surface and the conductive film on the PET film surface was measured. The volume resistivity was calculated from volume resistivity ρv (Ω · cm) = (R / L) × 10.

  Further, each of the prepared compositions for forming a resistance adjusting layer was separated into a sheet with a roll, formed into a sheet having a thickness of 3 mm, and then vulcanized by heat treatment at 160 ° C. for 45 minutes. This produced each sheet-like sample which measures the volume resistivity of each resistance adjustment layer.

  Thereafter, a 1 cm square electrode was applied to the front and back surfaces of each obtained sheet-like sample with a silver paste, and after drying, the thickness (L: mm) was measured. Subsequently, the resistance value (R: Ω) when 100 V was applied to the front and back electrodes was measured. The volume resistivity was calculated from volume resistivity ρv (Ω · cm) = (R / L) × 10.

3. Measurement of roll physical properties and roll evaluation For each of the obtained transfer rolls, roll hardness was measured, and images and interlayer adhesion were evaluated.

(Roll hardness)
Using a spring type hardness tester (rubber / plastic hardness meter / Asker C type: manufactured by Kobunshi Keiki Co., Ltd.), the axial direction of each transfer roll held horizontally with both ends supported by a V block Each roll hardness was measured by reading the scale after pressing the spring-type hardness tester perpendicularly with a load of 500 g (total load including the tester) against the surface of the central portion. And, the hardness obtained is “◎” when the hardness is less than 25 ° to less than 30 °, “◯” when the hardness is less than 30 ° to less than 32 °, “Δ” if the hardness is less than 32 ° to less than 35 °, 35 ° or more The thing of "x" was made.

(Interlayer adhesion)
About each transfer roll, the adhesive force between a resistance adjustment layer and a foaming layer was measured as follows. That is, after each transfer roll was cut in the circumferential direction with a width of 25 mm, the edge of the resistance adjustment layer made of a tube body was peeled off by an amount that could be gripped by a jig. Next, the resistance adjustment layer was held with a jig, and the resistance adjustment layer was peeled off.

  At this time, if the foam layer part peeled off, the resistance adjustment layer was peeled off because it was excellent in interlayer adhesion, but the foam adjustment layer was left at the interface of the resistance adjustment layer. “△” was evaluated as being slightly weak, and “×” was evaluated as being inferior in interlayer adhesion strength when the resistance adjusting layer was peeled off.

(Image evaluation)
Each transfer roll was incorporated in a secondary transfer unit of a commercially available electrophotographic apparatus as a secondary transfer roll, and a halftone image (image density 30%, A4) was printed out in A4 size. It was judged that there was no image defect when no black haze caused by the void portion was “◎”, and “x” was judged when an image defect occurred when the black haze caused by the void portion occurred.

  Table 1 summarizes each measurement result, evaluation result, and the like.

  A relative comparison of Table 1 shows the following. That is, the transfer roll according to Comparative Example 1 does not have an electrode layer on the inner peripheral surface of the resistance adjustment layer made of a tube body. For this reason, an image defect caused by the gap occurred in the sample in which a gap was formed between the tube body and the foamed layer.

  Therefore, if there is no electrode layer between the foam layer and the resistance adjustment layer, the flow of electrons is hindered by voids due to cell roughness or void defects on the surface of the foam layer generated during roll production, It can be seen that uneven resistance occurs and an image defect occurs.

  The transfer rolls according to Comparative Examples 2 and 3 are different from the transfer roll according to Comparative Example 1 in that an electrode layer is provided between the foam layer and the resistance adjustment layer. However, in the transfer rolls according to Comparative Examples 2 and 3, the volume resistivity of the electrode layer is larger than the volume resistivity of the foamed layer, and does not satisfy the volume resistivity relationship defined in the present invention. For this reason, an image defect caused by the gap occurred in the sample in which a gap was formed between the tube body and the foamed layer.

  From this, even if it has an electrode layer between the foam layer and the resistance adjustment layer, as defined in the present invention, the volume resistivity of the electrode layer is not less than or equal to the volume resistivity of the foam layer, It can be seen that in addition to the voids, the electrode layer becomes an electrical resistance and the flow of electrons is hindered, and image defects cannot be suppressed.

  The transfer roll according to Comparative Example 4 has an electrode layer between the foam layer and the resistance adjustment layer, and the relationship between the volume resistivity of the electrode layer and the volume resistivity of the foam layer is defined in the present invention. Satisfying the relationship. However, the transfer roll according to Comparative Example 4 has an electrode layer made of a polyamide resin and does not have rubber elasticity.

  Therefore, it turns out that roll hardness is hard and it is inferior to the interlayer adhesion between a foaming layer and a resistance adjustment layer. Since the transfer roll is normally pressed against the mating member at a relatively high pressure as compared with a developing roll or a charging roll, high durability cannot be obtained unless the interlayer adhesion is sufficient. That is, it can be said that the transfer roll according to Comparative Example 4 is inferior in roll performance in this respect.

  On the other hand, in contrast to the transfer rolls according to these comparative examples, the transfer rolls according to Examples 1 to 7 have image defects caused by the gaps, including the sample in which the gaps are formed between the tube body and the foam layer. Did not occur.

  Therefore, even when a gap is generated between the foam layer and the resistance adjustment layer due to cell roughness or void defects on the surface of the foam layer, electrons easily flow due to the presence of the electrode layer. It can be seen that image defects due to uneven electrical resistance can be suppressed.

  It can also be seen that even when an electrode layer is introduced, the hardness suitable as a transfer roll can be maintained, and since the interlayer adhesion is excellent, high durability can be exhibited.

  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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transfer roll 12 Shaft body 14 Foam layer 16 Electrode layer 18 Resistance adjustment layer 20 Surface layer

Claims (7)

A shaft,
A foam layer formed on the outer periphery of the shaft body;
An electrode layer formed on the outer periphery of the foam layer;
At least a resistance adjustment layer formed of a tube body formed on the outer periphery of the electrode layer,
The foam layer, the electrode layer, and the resistance adjustment layer all have rubber elasticity,
The volume resistivity of the electrode layer is less than or equal to the volume resistivity of the foamed layer.   The polymer mainly constituting the electrode layer is a polymer mainly constituting the foam layer and / or a polymer similar to the polymer mainly constituting the resistance adjusting layer. The transfer roll for electrophotographic equipment as described. The polymer mainly constituting the foamed layer is one or more selected from ethylene-propylene-diene rubber, hydrin rubber, and urethane rubber,
The polymer mainly constituting the electrode layer is one or more selected from ethylene-propylene-diene rubber, hydrin rubber, and nitrile rubber,
3. The electron according to claim 1, wherein the polymer mainly constituting the resistance adjusting layer is one or more selected from ethylene-propylene-diene rubber, hydrin rubber, and nitrile rubber. Transfer roll for photographic equipment. 4. The transfer roll for an electrophotographic apparatus according to claim 1, wherein the electrode layer has a volume resistivity in a range of 1 × 10 ³ to 1 × 10 ⁶ Ω · cm.   5. The transfer roll for an electrophotographic apparatus according to claim 1, wherein the electrode layer has a thickness in a range of 5 to 100 μm.   The transfer roll for an electrophotographic apparatus according to any one of claims 1 to 5, wherein a surface layer is formed on an outer periphery of the resistance adjustment layer. A step of preparing a tube body to be a resistance adjusting layer, with the electrode layer forming composition attached to the inner peripheral surface thereof;
In the roll molding die, the step of coaxially installing the prepared tube body and the shaft body with the foam layer forming composition attached to the outer peripheral surface;
A method for producing a transfer roll for an electrophotographic apparatus, comprising: foaming the composition for forming a foam layer, and integrating the formed foam layer and an electrode layer.

Images