JP2010072315A - Roll for electrophotographic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roll for electrophotographic equipment which can demonstrate a uniform charging property in the roll for the electrophotographic equipment with a middle high shape which can abut uniformly to an object to be abutted to. <P>SOLUTION: The roll is a middle high shape having an outside diameter in a central section in the axial direction of the roll body 3 formed to be greater than the outer diameters in end sections in the axial direction. The roll body 3 has the thickness of an adhesive layer 31 formed to be the middle high shape having the central section in the axial direction highest and made gradually thinner going toward both end section sides. A conductive roll 1 is constituted so that the thickness of the conductive layer 32 is formed to be approximately the same from one end section to the other end section in the axial direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a roll for electrophotographic equipment, and more particularly to a roll for electrophotographic equipment having a middle and high shape in which a central portion in the axial direction is formed thicker than an end portion in the axial direction.

  2. Description of the Related Art Conventionally, electrophotographic apparatuses such as copying machines, printers, and facsimiles using an electrophotographic system have been widely used. In these electrophotographic apparatuses, a photoreceptor such as a photoreceptor drum for forming an electrostatic latent image is incorporated. As a roll used in such an electrophotographic apparatus, for example, a semiconductive rubber roller type charging roll is used in order to form the electrostatic latent image by charging the photosensitive member. The charging roll is configured by providing a roll body having a conductive elastic layer made of a rubber composition on the outer peripheral surface of a metal core in order to uniformly charge a photosensitive body such as a photosensitive drum. ing.

  When the charging roll is brought into contact with a contacted object such as a photosensitive drum, a method is generally used in which a load is applied to the cored bar portions at both ends and pressed against the contacted object. It is desirable that the charging roll be in uniform contact with the object to be contacted to improve the grounding property. In order to improve the grounding property of the charging roll, it is known that the outer diameter of the roll body is maximized at the center in the axial direction and is formed in a medium-high shape that gradually decreases toward both ends (for example, patents) Reference 1). Such a shape of the charging roll in which the roll body is formed in a middle-high shape drum shape is generally called a middle-high shape.

Japanese Patent No. 2753925

  As shown in FIG. 4, for example, a charging roll 100 having a medium to high shape has a roll body 102 formed by laminating a conductive elastic layer 104 on an outer periphery of a cored bar 101 with an adhesive layer 103 interposed therebetween. The adhesive layer 103 is applied with a certain thickness from one end to the other end in the axial direction. And the roll body 102 is formed in the medium-high shape because the thickness of the said electroconductive elastic layer 104 is formed so that it may become thick gradually from the edge part of an axial direction to the center part.

  However, in the conventional charging roll 100, since the thickness of the conductive elastic layer 104 is different between the central part and the end part in the axial direction, the electrostatic capacity at the central part and the end part in the axial direction of the roll body 102 is different. Become. In the charging roll 100, when the electrostatic capacity changes depending on the position in the axial direction, the electrostatic capacity is biased, and there is a problem that uniform chargeability cannot be ensured at the central part and the end part in the axial direction. there were.

  Accordingly, the problem to be solved by the present invention is to provide a roll for electrophotographic equipment that can ensure uniform chargeability in a roll for electrophotographic equipment having a medium-high shape that can uniformly abut against an object to be abutted. There is to do.

  The roll for an electrophotographic apparatus of the present invention has a shaft body and a roll body having at least an adhesive layer and a conductive elastic layer formed on the outer periphery of the shaft body, and the outer diameter of the central portion in the axial direction of the roll body is a shaft. In the roll for medium and high shape electrophotographic equipment formed larger than the outer diameter of the end portion in the direction, the adhesive layer has a middle and high shape in which the thickness of the central portion in the axial direction of the roll body is thicker than the thickness of the end portion in the axial direction The adhesive layer is formed such that the thickness of the roll body in the axial direction is substantially constant.

In the roll for an electrophotographic apparatus, the adhesive layer preferably has a volume resistivity in the range of 1.0 × 10 ^{2 to} 3.0 × 10 ⁵ Ω · cm.

  The roll for an electrophotographic apparatus of the present invention is formed in a medium-high shape in which the thickness of the central portion in the axial direction of the roll body of the adhesive layer is thicker than the thickness of the end portion in the axial direction, and the roll body of the conductive elastic layer By forming the axial thickness substantially constant, the electrostatic capacity of the center portion and the end portion of the roll body does not change, and uniform charging performance can be obtained over the entire axial width.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external perspective view showing an example of a charging roll as an example of the roll for electrophotographic equipment of the present invention, FIG. 2 is a sectional view taken along line BB showing a circumferential section of FIG. 1, and FIG. It is CC sectional view taken on the line which shows the axial direction cross section of 1. FIG. As shown in FIG. 1 to FIG. 3, the charging roll 1 is formed on the surface of the roll body 3, the shaft body 2 made of a cylindrical cored bar, the roll body 3 laminated on the outer periphery of the surface of the shaft body 2. And the protective layer 4 formed. The roll body 3 includes an adhesive layer 31 formed on the shaft body 2 side and a conductive elastic layer 32 laminated on the outer periphery of the adhesive layer 31.

  The shaft body 2 can be a metal core made of a solid metal such as iron, aluminum, or stainless steel, a metal cylindrical body hollowed inside, or a conductive shaft plated with these. . Moreover, you may apply | coat a primer etc. to the outer peripheral surface of the shaft body 2, and may process the surface as needed. The primer may be conductive as necessary.

  As shown in FIG. 3, the roll body 3 is formed in a medium-high shape in which the outer diameter of the central portion M1 in the axial direction of the roll body 3 is larger than the outer diameters of the axial end portions E1 and E2. As shown in FIG. 3, the thickness of the adhesive layer 31 of the roll body 3 is thickest at the center in the axial direction and gradually becomes thinner toward the both ends (when called a crown shape). Is also formed). The roll body 3 is formed such that the conductive elastic layer 32 has substantially the same thickness from one end portion in the axial direction of the roll body 3 to the other end portion.

  The adhesive layer 31 is provided for adhering the conductive elastic layer 32 to the shaft body 2 and for imparting a medium-high shape to the roll body 3. As shown in FIG. 3, the adhesive layer 31 is formed in a medium-high shape so that its thickness continuously increases from the axial end portions E1 and E2 toward the central portion M1, and the shaft of the adhesive layer 31 is formed. In order to obtain a more uniform charging characteristic, it is preferable that the directional cross-sectional shape is substantially an arc shape.

  The adhesive layer 31 is preferably formed to have a thickness of 5 to 105 μm. Moreover, it is preferable that the difference between the thickness of the thickest portion of the middle and high shape of the adhesive layer 31 and the thickness of the thinnest portion is in the range of 50 to 100 μm. If the difference in thickness is less than 50 μm, the effect of uniformizing the charging performance may be insufficient. If the difference in thickness exceeds 100 μm, the volume resistivity of the adhesive layer 31 may be affected. May grow.

When the volume resistivity of the adhesive layer 31 is increased, the electrical resistance of the roll body 3 is reduced between a thick portion near the center and a thin portion near both ends. There is a risk that the change will increase. When the electrical resistance changes in the axial direction of the roll body 3, the charging performance of the charging roll 1 is degraded. On the other hand, if the volume resistivity of the adhesive layer 31 is low to some extent, the change in electrical resistance due to the difference in thickness can be reduced. Specifically, the adhesive layer 31 preferably has a volume resistivity of the material in the range of 1.0 × 10 ^{2 to} 3.0 × 10 ⁵ Ω · cm. When the volume resistivity of the adhesive layer 31 is within the above range, there is no possibility that the charging performance of the charging roll 1 is lowered due to the difference in the thickness of the adhesive layer, and stable charging performance can be exhibited. The adhesive layer 31 can have a volume resistivity within the above range by appropriately selecting a constituent material.

  The material of the adhesive layer 31 may be any material as long as the shaft body 2 and the conductive elastic layer 32 can be bonded. For example, the rubber layer, the phenol resin, the epoxy resin, the acrylic resin, and the polyurethane are used. Adhesives such as nitrile rubber, styrene-butadiene (SBR), and natural rubber can be used. The adhesive layer 31 may be mixed with a conductive agent as necessary to adjust the conductivity.

  The adhesive layer 31 is made of a vulcanized adhesive that can be cured by heat, pressure, or the like at the time of vulcanization molding of the conductive elastic layer 32 to bond the shaft body 2 and the conductive elastic layer 32. It may be used. Examples of the vulcanized adhesive include, for example, chlorinated rubber-based, phenol resin-based, epoxy resin-based, and nitrile rubber-based adhesives in the above-described adhesive.

  The conductive elastic layer 32 is formed along the outer peripheral surface of the lower adhesive layer 31 for the purpose of resistance adjustment for adjusting the electrical resistance of the charging roll 1. As shown in FIG. 3, the thickness of the conductive elastic layer 32 is such that the thickness over the entire area in the axial direction from the axial end portion E1 through the central portion M1 to the other end portion E2 is substantially the same. Is formed. As a result, the surface of the roll body 3 is formed in a medium-high shape with a curvature along the medium-high shape of the adhesive layer 31. Thus, the electroconductive elastic layer 32 is not formed in the middle-high shape like the conventional roll body. Since the conductive elastic layer 32 has a constant thickness from one end in the axial direction to the other end, there is no difference in capacitance due to the difference in position between the end in the axial direction and the center. . Therefore, the roll body 3 of the charging roll 1 has the same capacitance at any position in the axial direction.

The thickness of the conductive elastic layer 32 is usually formed to be about 0.1 to 10 mm, and preferably in the range of 1 to 5 mm. The conductive elastic layer 32 preferably has a volume resistivity within a range of 1.0 × 10 ^{6 to} 5.0 × 10 ⁸ Ω · cm. The conductive elastic layer 32 may be a solid non-foamed material or a sponge-like foamed material.

  The conductive elastic layer 32 includes, for example, polynorbornene rubber, silicone rubber, ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (H-NBR), and styrene-butadiene rubber (SBR). ), Butadiene rubber (BR), isoprene rubber (IR), natural rubber (NR) and the like are used as the main component. These may be used alone or in combination.

  The conductive elastic layer 32 preferably uses an ion conductive polymer as a main component. When an ion conductive polymer is used as the main component of the conductive elastic layer 32, the roll body 3 can have excellent characteristics such as low sag, conductivity, and flexibility. Examples of the ion conductive polymer include acrylonitrile-butadiene rubber (NBR) and epichlorohydrin rubber. The above epichlorohydrin rubber is composed of a homopolymer of epichlorohydrin (CO), a copolymer of epichlorohydrin and ethylene oxide (ECO), a copolymer of epichlorohydrin and allyl glycidyl ether (GCO), a copolymer of epichlorohydrin, ethylene oxide and allyl glycidyl ether. A polymer (GECO) etc. are mentioned. These ion conductive polymers may be used alone or in combination of two or more.

In addition to rubber components such as an ion conductive polymer, the conductive elastic layer 32 is carbon black, graphite, potassium titanate, iron oxide, c-TiO ₂ , c-ZnO, c-SnO ₂ , Conductive agents (electronic conductive agent and / or ionic conductive agent) such as quaternary ammonium salts, borates, and surfactants can be added. In addition to the main components described above, the conductive elastic layer 32 includes a filler, reinforcing agent, processing aid, curing agent, vulcanization accelerator, crosslinking agent, crosslinking aid, antioxidant, plasticizer, ultraviolet absorber, You may add 1 type, or 2 or more types of various additives, such as oil, a lubrication agent, adjuvant, and surfactant.

The protective layer 4 is formed on the outer peripheral surface of the conductive elastic layer 32 as a surface protective layer for protecting the surface of the roll body 3 for the purpose of preventing sticking to the photoreceptor. The protective layer 4 preferably has a thickness in the range of 0.1 to 20 μm. In the case of the charging roll 1, the protective layer 4 is preferably formed to be semiconductive by providing a certain degree of conductivity. The protective layer 4 preferably has a volume resistivity in the range of 1 × 10 ⁶ to 1 × 10 ¹⁰ Ω · cm.

  Examples of the material for the protective layer 4 include silicone resins, fluorine resins, polymethyl methacrylate (PMMA), polycarbonate, polyamide resins, urethane resins, acrylonitrile-butadiene rubber (NBR), epichlorohydrin rubber, and the like. Rubbers, modified products obtained by modifying these resins or rubbers with silicone, fluorine, or the like are used. The protective layer 4 may contain two or more of the above rubbers and resins.

  The protective layer 4 is made of a conductive agent (an electronic conductive agent such as carbon black and / or an ionic conductive agent such as a quaternary ammonium salt), a release agent, a curing agent, etc. One type or two or more types of additives may be contained.

  Hereinafter, a method for manufacturing the charging roll 1 will be described. In order to manufacture the above-described charging roll 1, first, the adhesive layer 31 is formed on the outer periphery of the shaft body 2 to have a medium-high shape in which the thickness gradually increases from both axial ends toward the center. As a method for forming the adhesive layer 31 in a medium-high shape, for example, a method of repeatedly performing overcoating by gradually changing the coating length in the axial direction using various coating methods such as brushing or spraying. It is done. That is, it is only necessary to apply a portion to be thickly formed a plurality of times while changing the application width so that the number of times of application of the adhesive is increased.

  Next, the conductive elastic layer 32 is provided on the outer periphery of the adhesive layer 31 to form the roll body 3. In order to form the conductive elastic layer 3, a conductive elastic layer in which the components constituting the conductive elastic layer 32 are blended on the outer peripheral surface of the adhesive layer of the shaft body 2 provided with the adhesive layer 31. A method of extruding the composition, the shaft body 2 provided with the adhesive layer 31 is coaxially installed in the hollow portion of a roll molding die, and the conductive elastic layer composition is injected into the die and heated. -A method of demolding after curing can be used. The conductive elastic layer 32 may be vulcanized as necessary.

  Next, the protective layer 4 is formed on the outer peripheral surface of the conductive elastic layer 32 of the roll body 3 to obtain the charging roll 1. The protective layer 4 is made of a protective layer composition in which a conductive agent such as carbon black or conductive metal oxide is blended with resin or rubber by a predetermined method such as a roll coating method, a dipping method, or a spray coating method. It can be formed by coating the surface of the elastic layer 32 and drying (curing) it.

  In the above embodiment, the charging roll has been described as an example. However, the roll for an electrophotographic apparatus of the present invention is not limited to a charging roll, but may be a developing roll, a transfer roll, a fixing roll, etc., such as an electrophotographic copying machine or printer. Thus, if both ends of the shaft body are pressed by a spring or the like so as to abut against the abutted roll and follow the abutted roll and rotate, then apply. Can do.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
<Shaft>
As the metal core, a shaft body made of SUS304 having an outer diameter of 8 mm and a length of 340 mm was used.

<Adhesive layer>
As the adhesive layer, a phenol resin adhesive having a volume resistivity of 3.1 × 10 ⁴ Ω · cm [manufactured by Toyo Chemical Laboratory, trade name “Metallock N-33”] was used.

  The volume resistivity of the adhesive was measured using the following method. An adhesive was applied to the surface of the conductive PET using a bar coat having a gap of 0.5 mm, then air-dried, and further heated at 100 ° C. for 1 hour to form an adhesive coating. The adhesive coating film was made to have a film thickness after drying in the range of 0.4 to 0.6 mm. Then, in an environment of room temperature 23 ° C. and humidity 53%, a resistance meter (Kesley: Model 237 High-Voltage Source) is provided on the front and back surfaces of the adhesive coating film via rubber electrodes [manufactured by Hioki Denki, trade name “SME-8311”]. -Measurement Unit) was connected, and an applied voltage of 1 V (10 seconds) was applied to measure the resistance value. The volume resistivity was determined from the measured resistance value and the cross-sectional area and thickness of the adhesive coating film. The volume resistivity of the conductive elastic layer and the protective layer described later was also determined by the same method.

<Preparation of conductive elastic layer forming composition>
The conductive elastic layer forming composition is composed of 100 parts by mass of epichlorohydrin rubber (ECO) [trade name “Epichromer CG102”] manufactured by Daiso Co., Ltd. as a main component and liquid acrylonitrile-butadiene copolymer (liquid NBR) [JSR Co., Ltd. ), Trade name “JSR N280”] 10 parts by mass, sulfur as a vulcanizing agent (manufactured by Tsurumi Chemical Co., Ltd.) 0.5 part by mass, and vulcanization aid 2 types of zinc oxide [Mitsui Metal Industries ( Co., Ltd.] 5.0 parts by mass and hydrotalcite [manufactured by Kyowa Chemical Industry Co., Ltd., trade name “DHT4A”] 10.0 parts by mass, vulcanization accelerator A [manufactured by Sanshin Chemical Industry Co., Ltd., product Name "Sunseller CZ"] 1.0 part by mass, vulcanization accelerator B [manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name "Accel TBT"] 1.0 part by mass, as an ionic conductive agent in the following structural formula 4th class Ammonius represented A composition was prepared by kneading 1.0 part by mass of a salt with a kneader. The volume resistivity of the conductive elastic layer formed from this composition was 6.7 × 10 ⁶ Ω · cm.

<Preparation of protective layer forming composition>
The protective layer-forming composition is composed of 100 parts by mass of N-methoxymethylated nylon [manufactured by Teikoku Chemical Industry Co., Ltd., trade name “Tresin EF30T”] and melamine resin [manufactured by Sumitomo Chemical Co., Ltd., trade name “Smitex Resin” M3 "] was dissolved in 500 parts by mass of a methanol-toluene mixed solution (methanol: toluene = 7: 3) to prepare a composition. The volume resistivity of the protective layer formed from this composition was 6.0 × 10 ⁹ Ω · cm.

<Manufacture of charging roll>
In the present example, a charging roll having a length of 320 mm and a roll body having the structure shown in FIG. 3 was produced. First, the adhesive on the surface of the shaft body, the application length of the adhesive in the axial direction is 320 mm (first), 280 mm (second), 240 mm (third), 200 mm (fourth), 160 mm (fifth), The coating was gradually shortened to 120 mm (sixth time) and 80 mm (seventh time), and overcoated seven times. Each application was made such that the application length was the same from the axial center of the shaft body to both ends. The amount of adhesive applied was such that the film thickness of one application was about 10 μm. As shown in FIG. 3, the adhesive layer was formed such that the number of times of application was the largest in the central portion in the longitudinal direction of the shaft body and the film thickness was thick, and the thickness gradually decreased toward the end side. The thickness of the adhesive layer is 0.070 mm at the central portion M1, a position (end portion 1) at a distance of 150 mm from the central portion M1 to one end side, and a position (end portion) from the central portion M1 to the other end side. Part 2) was 0.010 mm. The drying condition of the adhesive was 60 ° C. × 15 min.

  Next, the shaft body on which the adhesive layer is formed is set in a pipe-shaped mold having a mold shape corresponding to the crown shape of the roll body, and then the conductive elastic material is placed in the pipe-shaped mold. After injecting the layer forming composition (unvulcanized rubber), it was heated at 180 ° C. for 30 minutes and vulcanized to form a conductive elastic layer. Further, the protective layer-forming composition is applied to the surface of the conductive elastic layer by a roll coating method to a thickness of 8 μm, heated at 120 ° C. for 50 minutes to be crosslinked, and a diameter of 12.05 mm (center in the axial direction). A charging roll having a medium-high roll body was produced. The thickness of the conductive elastic layer was 1.955 mm at the axial center M1, and 1.95 mm at the axial end 1 and end 2.

  The drum charge amount of the obtained charging roll was measured by the following measuring method. The measurement results are shown in Table 1. The drum charge amount was measured at the center (M1), the end 1 and the end 2 of the roll body. The results are shown in Table 1. As shown in Table 1, in the charging roll of Example 1, the drum charging amount in the central portion, the end portion 1, and the end portion 2 is substantially the same, and the axial charging that is the difference in the charging amount between the end portion and the central portion is performed. The value of the amount Δ was 2V, and it had uniform chargeability. Note that the drum charge amount was evaluated as ◯ when the axial charge amount Δ was 10 V or less, Δ when it was more than 10 V to 20 V or less, and × when it was more than 20 V.

  The charging amount of the drum is determined by applying a load of 1400 gf to a photosensitive member (made by Fuji Xerox Co., Ltd., using a photosensitive drum of a trade name “CT350376 drum cartridge”) with a charging roll and bringing the photosensitive member in rotation at 60 rpm. Using a high-voltage power supply (manufactured by TREK) and a pulse oscillator (manufactured by NF circuit design Gr), -0.7 kV DC voltage and 1.6 kVp-p, 2 kHz under normal temperature and normal pressure environment The surface potential on the photosensitive drum was measured with a surface potential meter (manufactured by TREK) in a dark room.

Example 2
The same as in Example 1 except that a phenol resin adhesive having a volume resistivity of 2.3 × 10 ⁵ Ω · cm [manufactured by LORD, trade name “Chemlock XJ150”] was used as the adhesive of the adhesive layer. A charging roll of Example 2 was manufactured by forming a conductive elastic layer and a protective layer. For the obtained charging roll of Example 2, the drum charge amount was measured in the same manner as in Example 1 to evaluate the charging property. The evaluation results are shown in Table 1. As shown in Table 1, the charging roll of Example 2 had an axial charging amount Δ of 5 V and had uniform charging properties.

Comparative Example 1
The adhesive layer is formed to have a constant thickness (0.01 mm) from end to end in the axial direction, and the thickness of the conductive elastic layer is set to a medium-high shape with a thick central portion and a thin end portion. A charging roll of Comparative Example 1 was produced using the same adhesive, conductive elastic layer composition, and protective layer forming composition as Example 1, except that the shape was the same as Example 1. . The thickness of the conductive elastic layer was 2.015 mm at the axial center M1, and 1.954 mm at the axial end 1 and end 2. For the charging roll of Comparative Example 1, the drum charge amount was measured in the same manner as in Example 1 to evaluate the charging property. The evaluation results are shown in Table 1. As shown in Table 1, the charging roll of Comparative Example 1 had an axial charge amount Δ of 13V.

Comparative Example 2
Adhesive using a phenolic resin adhesive with a volume resistivity of 8.4 × 10 ¹⁰ Ω · cm [trade name “Metallock N-15D” manufactured by Toyo Chemical Laboratory, Inc.] as the adhesive of the adhesive layer The agent layer is formed to a constant thickness (0.01 mm) from end to end in the axial direction, and the thickness of the conductive elastic layer is set to a medium-high shape with a thick central part and a thin end part. The charging roll of Comparative Example 2 was produced using the same conductive elastic layer composition and protective layer forming composition as Example 1, except that the composition was the same as Example 1. The thickness of the conductive elastic layer was 2.015 mm at the axial center M1 and 1.955 mm at the axial end 1 and end 2. For the charging roll of Comparative Example 2, the drum charge amount was measured in the same manner as in Example 1 to evaluate the charging property. The evaluation results are shown in Table 1. As shown in Table 1, the charging roll of Comparative Example 2 had an axial charge amount Δ of 27V.

It is an external appearance perspective view which shows the example of a charging roll as an example of the roll for electrophotographic apparatuses of this invention. It is the BB sectional view taken on the line of FIG. It is CC sectional view taken on the line of FIG. It is an axial sectional view showing a conventional charging roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charging roll 2 Shaft body 3 Roll body 31 Adhesive layer 32 Conductive elastic layer

Claims (2)

  A roll body having at least an adhesive layer and a conductive elastic layer is formed on the outer periphery of the shaft body and the shaft body, and the outer diameter of the central portion in the axial direction of the roll body is larger than the outer diameter of the end portion in the axial direction. In the medium-high shape roll for electrophotographic equipment, the adhesive layer is formed in a medium-high shape in which the thickness of the central portion in the axial direction of the roll body is thicker than the thickness of the axial end portion, and the conductive elastic layer is The roll for electrophotographic equipment is characterized in that the axial thickness of the roll body is substantially constant. The roll for electrophotographic equipment according to claim 1, wherein the volume resistivity of the adhesive layer is in the range of 1.0 × 10 ^{2 to} 3.0 × 10 ⁵ Ω · cm.

Images