JP5481855B2 - Elastic roll, charging device, process cartridge, and image forming apparatus - Google Patents

Description

The present invention is an elastic roll, band collector, a process cartridge and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer that employs an electrophotographic method, for example, as a charging device, a direct contact is made with the surface of an object to be charged (for example, a photoreceptor) to In general, a proximity or contact type charging device that applies a voltage superposed on the object to be charged is used, or a transfer device that transfers a toner image formed on the object to be charged onto a transfer medium such as paper. .

  As a charging roll used in such a proximity or contact type charging device or a transfer roll used in a transfer device, for example, control of electric resistance and adhesiveness between a conductive metal core which is a rotating shaft and an elastic layer are used. In order to achieve both, it has been proposed to provide an adhesive layer having a higher volume resistivity than the elastic layer between the conductive core metal and the elastic layer (for example, Patent Documents 1 and 2).

  In addition, in order to strongly bond the conductive elastic layer and the rotating shaft, an adhesive containing no carbon powder is spirally applied to the rotating shaft, and then the conductive elastic layer is attached to the conductive shaft and the uncoated portion of the rotating shaft. There has been proposed a charging roll in which conductivity is secured by directly contacting an elastic layer in a spiral shape (for example, Patent Document 3).

  Further, a first adhesive layer is formed on the outer periphery of the shaft body, and a second adhesive layer containing carbon black is laminated by extending from both ends of the first adhesive layer, and then on the second adhesive layer After laminating the rubber layer, the second adhesive layer and the rubber layer are cut along the both ends of the first adhesive layer, and the both ends of the second adhesive layer and the rubber layer are removed. A method for producing a charging roll has been proposed in which the end portions of the first adhesive layer, the second adhesive layer, and the rubber layer are aligned to prevent diameter expansion at both end edges of the rubber layer (for example, Patent Document 4).

Japanese Patent Laid-Open No. 9-190049 Japanese Patent Laid-Open No. 9-272178 JP-A-11-102113 JP 2004-302127 A

  The present invention provides an elastic roll that suppresses the occurrence of rust in a conductive core of an elastic roll having a history of use, a method for manufacturing the elastic roll, and a charging device, a process cartridge, and an image forming apparatus provided with the elastic roll The purpose is to provide.

The above-mentioned subject is achieved by the following present invention. That is, the elastic rolls, strips collector of the present invention, a process cartridge and an image forming apparatus has the following features.

( 1 ) On a conductive mandrel, at least an insulating first adhesive layer, a conductive second adhesive layer, and a semiconductive elastic layer are laminated in this order, and the second adhesive layer is It is electrically connected to the conductive core, and the axial end of the second adhesive layer extends from the axial end of the first adhesive layer and the axial end of the elastic layer. And a third adhesive layer having an end portion extending from an axial end portion of the first adhesive layer and having a volume resistivity lower than that of the second adhesive layer. , third adhesive layer is elastic rolls that are in contact with at least a portion and the conductive core metal and the second adhesive layer.

(2) is a charging device comprising an elastic roll according to the above (1).

(3) a process cartridge having an elastic roll according to the above (1).

( 4 ) An image forming apparatus comprising: at least an image holding member; and the elastic roll according to the above (1 ) that contacts the image holding member and charges the surface thereof.

According to the first aspect of the present invention, it is possible to obtain an elastic roll excellent in adhesion and conductivity by suppressing the occurrence of rust of the conductive core due to the use history.

According to invention of Claim 2 , the charging device by which the rust generation | occurrence | production of the conductive metal core by the use log | history was suppressed is provided.

According to the third aspect of the present invention, there is provided a process cartridge in which the rust generation of the conductive metal core due to the use history is suppressed.

According to the fourth aspect of the present invention, there is provided an image forming apparatus in which the rust generation of the conductive metal core due to the use history is suppressed.

  Embodiments of the present invention will be described below. In describing the embodiment of the present invention in detail, the elastic roll in the present embodiment will be described in detail, and then the process cartridge and the image forming apparatus provided with the elastic roll in the present embodiment will be described. In addition, the dimension of each structure of drawing may differ from an actual dimension.

<Elastic roll>
Elastic roll 100 of the first reference embodiment of the present invention, as shown in FIG. 1, the outer periphery of the conductive core metal 10, a first adhesive layer 12 of insulating at least coaxially, conductive The second adhesive layer 14 and the semiconductive elastic layer 16 are laminated, and the axial ends of the second adhesive layer 14 extend from the axial ends of the first adhesive layer 12, respectively. In addition, the conductive second adhesive layer 14 is electrically connected to the conductive core metal 10. Further, a surface layer (not shown) that is a resistance layer is laminated on the elastic layer 16. In the present embodiment, both end surfaces of the elastic layer 16 and both end surfaces of the second adhesive layer 14 are substantially flush with each other.

Here, the “conductive state” in the present invention means a case where the volume resistivity between the conductive metal core and the second adhesive layer is 1 × 10 ⁸ Ω · cm or less. In addition, the measuring method of volume resistivity is mentioned later.

For example, when image formation is performed using the elastic roll 100 of the reference embodiment as a contact charging roll in an image forming apparatus, the conductive second adhesive layer 14 is in electrical conduction with the conductive core 10. The current is supplied to the entire elastic roll 100, and as a result, the chargeability of the elastic roll 100 is not impaired. On the other hand, the charge transfer between the insulating first adhesive layer 12 and the surface of the conductive core 10 is as follows. For example, since it is smaller than the charge transfer between the conductive adhesive layer and the conductive core surface, the rust in the region where the first adhesive layer 12 of the conductive core 10 is formed due to the use history. Occurrence is suppressed.

  Here, it is considered that the reason why the conductive metal core of the elastic roll having a history of use is likely to generate rust is as follows. A current for charging the photosensitive member flows through the elastic roll. A part of this current moves ions in the conductive rubber forming the elastic layer and ions in the adhesive layer for bonding the elastic layer and the conductive core to the conductive core surface. Therefore, the surface of the conductive metal core is in a state where there are many ions, and the conductive metal core is easily corroded. Alternatively, when the electric charge is transferred between the conductive core metal and the adhesive layer by this current, a portion that is easily corroded is generated on the surface of the conductive core metal with an oxidation-reduction reaction.

  In order to prevent these, the transfer of electric charge between the conductive rubber and the conductive metal core forming the elastic layer or between the adhesive layer and the conductive metal core is eliminated, in other words, the conductive metal core and It is effective not to pass an electric current between the conductive rubber forming the elastic layer. However, in actual use, from the viewpoint of cost, reliability, etc., it is effective to supply current from the conductive metal core to the elastic layer.

In the reference embodiment, for example, an image forming region of the elastic roll 100 is used in order to achieve both the generation of rust on the surface of the conductive core 10 and the supply of electricity from the conductive core 10 to the elastic layer 16. An insulating first adhesive layer 12 is formed on the outer periphery of the conductive core 10 corresponding to the above, and the transfer of charges on the surface of the conductive core 10 is reduced. The occurrence of rust is suppressed. In particular, the generation of rust on the conductive core 10 in a high temperature and high humidity environment is suppressed. As a result, partial peeling between the conductive metal core 10 and the elastic layer 16 is suppressed. As a result, distortion of the shape of the elastic roll 100 in the image forming region is prevented, and image formation is performed using the elastic roll 10. In this case, the occurrence of image defects is suppressed.

  Further, since the conductive second adhesive layer 14 supplies current from the non-image forming area of the elastic roll 100 to the entire elastic roll 100, the charging performance is not impaired. Therefore, as described above, the first adhesion of the conductive metal core 10 in the elastic roll 100 having a history of use without impairing the adhesion, manufacturability, and charging performance between the conductive metal core 10 and the elastic layer 16. Rust generation in the image forming area where the layer 12 is formed is suppressed.

The material of each component of the elastic roll 100 in the reference embodiment will be described below. The conductive mandrel 10 has conductivity, and generally iron, copper, brass, stainless steel, aluminum, nickel or the like is used. Moreover, the material which plated the free-cutting steel as shown by JISG4804 with chromium, nickel, etc. may be sufficient. The plating may be either electrolytic plating or electroless plating. In addition to the roll shape, the conductive metal core 10 has a hollow pipe shape.

  The insulating adhesive forming the first adhesive layer 12 adheres to the conductive core 10 and has high adhesiveness to the second adhesive layer 14 and has a volume resistivity of the second adhesive. Any known adhesive may be used as long as the adhesive layer has a higher resistivity than the adhesive layer 14. As the adhesive for the first adhesive layer 12, for example, an adhesive mainly composed of olefin resin, acrylic resin, epoxy resin, phenol resin, polyurethane resin, chlorinated rubber, chloroprene rubber, acrylonitrile-butadiene copolymer rubber or the like is used. Preferably, Chemlock 607 (manufactured by Road Far East) is used. Further, the first adhesive layer 12 preferably does not contain conductive particles or semiconductive particles, which will be described later. However, the first adhesive layer 12 is conductive particles or semiconductive in an amount capable of suppressing charge transfer with the conductive core metal 10. May contain functional particles.

The volume resistivity of the first adhesive layer 12 is 1 × 10 ¹⁰ Ω · cm or more, preferably 1 × 10 ¹¹ Ω · cm or more, and 1 × 10 ¹⁶ Ω · cm or less, more preferably 1 × 10 ¹² Ω · cm or more and 1 × 10 ¹⁵ Ω · cm or less.

  The film thickness of the first adhesive layer 12 is 1 μm or more and 30 μm or less, preferably 3 μm or more and 20 μm or less, and more preferably 5 μm or more and 15 μm or less. The first adhesive layer 12 is preferably thicker than a normal adhesive layer in order to insulate without defects and to prevent deterioration of insulation due to diffusion of ions and the like.

The conductive adhesive forming the second adhesive layer 14 adheres to the first adhesive layer 12 and has high adhesiveness with the elastic layer 16, and has a volume resistivity of the first adhesive layer. Any known adhesive can be used as long as the adhesive layer has a resistivity lower than 12. As the adhesive for the second adhesive layer 14, for example, an adhesive mainly composed of olefin resin, acrylic resin, epoxy resin, phenol resin, polyurethane resin, chlorinated rubber, chloroprene rubber, acrylonitrile-butadiene copolymer rubber, or the like is used. Further, the second adhesive layer 14 contains conductive particles or semiconductive particles. Examples of the conductive particles or semiconductive particles include carbon black such as ketjen black and acetylene black, pyrolytic carbon, graphite, zinc, aluminum, copper, iron, nickel, chromium, titanium and other metals, ZnO-Al _{2 O 3, SnO 2 -Sb 2} O 3, In 2 O 3 -SnO 2, ZnO-TiO 2, MgO-Al 2 O 3, FeO-TiO 2, TiO 2, SnO 2, Sb 2 O 3, In 2 Ionic compounds such as metal oxides such as O ₃ , ZnO, and MgO are used, and these materials may be used alone or in combination of two or more. As the adhesive used for the second adhesive layer 14, for example, a material obtained by adding a conductive agent (Ketjen Black EC: manufactured by Lion Corporation) to Chemlock 258 (manufactured by Road Far East) is used. The addition amount of these conductive agents can be added as long as desired conductivity is obtained.

The volume resistivity of the second adhesive layer 14 is 1 × 10 ⁸ Ω · cm or less, preferably 1 × 10 ¹ Ω · cm or more and 1 × 10 ⁶ Ω · cm or less, and more preferably 1 × 10 ⁸ Ω · cm or less. × 10 ¹ Ω · cm or more and 1 × 10 ⁵ Ω · cm or less.

  The film thickness of the second adhesive layer 14 is 1 μm or more and 30 μm or less, preferably 3 μm or more and 20 μm or less, and more preferably 5 μm or more and 15 μm or less.

  The extension region of the second adhesive layer 14 extending from the axial end portion of the first adhesive layer 12 can be arbitrarily set within a range in which a conductive state can be ensured, but it is elastic from the viewpoint of ensuring electrical conduction reliably. It is preferably 0.1% or more and 1% or less with respect to the axial length of the layer 16. For example, when the length of the elastic layer 16 in the axial direction is 300 mm, the extension region of the second adhesive layer 14 is not less than 0.3 mm and not more than 3 mm, preferably not less than 1 mm and not more than 2 mm. In addition, although it is preferable that the extension area | region of the 2nd contact bonding layer 14 exists in a roll both ends, only one side may be sufficient.

  The semiconductive elastic layer 16 is conductive or semiconductive. Generally, conductive particles or semiconductive particles are dispersed in a resin material or rubber material, or an ionic conductive agent is mixed. It is a thing. The resin material is, for example, a polyester resin, an acrylic resin, a melamine resin, an epoxy resin, a urethane resin, a silicone resin, a urea resin, a polyamide resin or the like, and the rubber material is, for example, ethylene-propylene rubber, Butanediene, natural rubber, polyisobutylene, chloroprene rubber, silicone rubber, urethane rubber, epichlorohydrin rubber, fluorosilicone rubber, ethylene oxide rubber, or a foamed material obtained by foaming these is used.

Examples of conductive particles or semiconductive particles include carbon black, zinc, aluminum, copper, iron, nickel, chromium, titanium, and other metals, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , Metal oxides such as In ₂ O ₃ —SnO ₂ , ZnO—TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , Sb ₂ O ₃ , In ₂ O ₃ , ZnO, and MgO These materials may be used alone or in admixture of two or more. Furthermore, you may mix the 1 type (s) or 2 or more types of organic fillers, such as inorganic fillers, such as a talc, an alumina, a silica, and the fine powder of a fluororesin or a silicone rubber, as needed.

  Examples of ionic conductive agents include perchlorates or chlorates such as tetraethylammonium and lauryltrimethylammonium, alkali metals such as lithium and magnesium, and perchlorates or chlorates of alkaline earth metals. Or 2 or more types are mixed and used.

  The film thickness of the elastic layer 16 is 0.5 mm or more and 5 mm or less, preferably 1 mm or more and 4 mm or less.

As a material for forming the surface layer (not shown), for example, conductive particles or semiconductive particles are dispersed in a binder resin, or an ionic conductive agent is contained and its resistance is controlled, The volume resistivity of the surface layer is 1 × 10 ³ Ω · cm or more and 1 × 10 ¹⁴ Ω · cm or less, preferably 1 × 10 ⁵ Ω · cm or more and 1 × 10 ¹² Ω · cm or less, More preferably, it is 1 × 10 ⁷ Ω · cm or more and 1 × 10 ¹⁰ Ω · cm or less.

  Examples of the binder resin used for the surface layer include acrylic resin, cellulose resin, polyamide resin, methoxymerylated nylon, ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, and polyacrylate resin. Polyolefin resin such as polythiophene resin, tetrafluoroethylene (PFA), tetrafluoroethylene (FEP), polyethylene terephthalate (PET), styrene butadiene resin, melamine resin, epoxy resin, urethane resin, silicone resin, urea resin, etc. are used. .

The conductive particles or semiconductive particles used for the surface layer are the same as those used for the above-described semiconductive elastic layer 32, such as carbon black, zinc, aluminum, copper, iron, nickel, chromium, and titanium, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O ₃ —SnO ₂ , ZnO—TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , Sb ₂ O ₃ , In ₂ O ₃ , ZnO, MgO and other metal oxides or the like are used alone or in combination. Examples of ionic conductive agents include perchlorates or chlorates such as tetraethylammonium and lauryltrimethylammonium, alkali metals such as lithium and magnesium, and perchlorates or chlorates of alkaline earth metals. Or 2 or more types are mixed and used. If necessary, an antioxidant such as hindered phenol or hindered amine, an inorganic filler such as clay, kaolin, talc, silica or alumina, or an organic filler such as fine powder of fluororesin or silicone resin, or Two or more kinds may be mixed. Further, a surfactant, a charge control agent and the like are added as necessary.

  The film thickness of the surface layer is, for example, 0.01 μm or more and 1,000 μm or less, preferably 0.1 μm or more and 500 μm or less, and more preferably 0.5 μm or more and 100 μm or less.

  The volume resistivity of the first adhesive layer 12, the second adhesive layer 14, the elastic layer 16, and the surface layer described above is measured as follows. That is, using a gap gauge on a 100 mm × 100 mm, 2 mm thick aluminum material, a 10 μm coating film is formed using a coating liquid for forming each layer, and 5 V is applied using R8340A manufactured by Advantest Corporation. Measured under voltage.

(Volume resistivity and their measurement)
Here, the volume resistivity can be measured according to JIS K 6911 (1995) using a circular electrode (for example, R8340A manufactured by Advantest Corporation or Hiresta UPMCP-450 UR probe manufactured by Dia Instruments Co., Ltd.). A method for measuring the volume resistivity will be described with reference to the drawings. FIG. 12 consists of FIG. 12A of a schematic plane showing an example of a circular electrode and FIG. 12B of a schematic cross section. The circular electrode shown in FIG. 12 includes a first voltage application electrode A and a second voltage application electrode B. The first voltage application electrode A has a columnar electrode portion C and a cylindrical ring electrode having an inner diameter larger than the outer diameter of the columnar electrode portion C and surrounding the columnar electrode portion C at a constant interval. Part D is provided. The above-described measurement sample T is sandwiched between the cylindrical electrode portion C and the ring electrode portion D in the first voltage application electrode A and the second voltage application electrode B, and the cylindrical electrode portion C in the first voltage application electrode A. The current I (A) flowing when the voltage V (V) is applied between the second voltage application electrode B and the second voltage application electrode B is measured 10 seconds after the voltage application, and the volume resistivity ρv of the measurement sample is expressed by the following equation (1). (Ωcm) can be calculated. Here, in following formula (1), t shows the thickness of the adhesive bond layer of a measurement sample.
Formula (1): ρv = 19.6 × (V / I) × t

(Measurement of resistance between the conductive core and each layer)
The resistance value between the conductive core and the first adhesive layer 12 and the second adhesive layer 14 described above is an average value of values measured by the method described in JP-A-6-118105.

The average value of the resistance is based on the resistance value measured by the following method. In the axial direction, 20 mm from the both end portions of the adhesive layer on the conductive support, respectively, three points in the central portion, and the circumference of the three points. In the direction, resistance was measured every 6 degrees, and all measured values were obtained by arithmetic averaging. In this resistance measurement, an electrode composed of a cylindrical SUS bearing having a width of 5 mm is brought into contact with the roll surface to be measured with a weight of 25 g, and the resistance between the electrode and the conductive support is rotated while the roll is rotated at 5.5 rpm. Was measured. As the power source and ammeter, a high resistance measuring device (R8340A digital high resistance / microammeter manufactured by Advantest) was used. The applied voltage was 1 V, and the resistance was calculated from equation (2).
Formula (2): Resistance (Ω) = applied voltage / current

  Further, the first adhesive layer 12, the second adhesive layer 14, the elastic layer 16 and the surface layer described above are prepared by applying a coating liquid whose composition is prepared for each layer, for example, a blade coating method, a Meyer bar coating method, It is formed by coating by a spray coating method, a dip coating method (shown in FIG. 7), a bead coating method, an air knife coating method, a curtain coating method, or the like.

As shown in FIG. 2, the elastic roll 110 according to the first embodiment of the present invention has at least a concentric insulating first adhesive layer 22 and a conductive core on the outer periphery of the conductive core 10. The second adhesive layer 24 and the semiconductive elastic layer 16 are laminated, and the axial end portions of the second adhesive layer 24 are respectively extended from the axial end portions of the first adhesive layer 22. The conductive second adhesive layer 24 is electrically connected to the conductive core 10. Further, a surface layer (not shown) that is a resistance layer is laminated on the elastic layer 16. Further, in the present embodiment, as shown in FIG. 2, both end faces of the elastic layer 16 and both end faces of the first adhesive layer 24 are substantially flush with each other.

  When image formation is performed using the elastic roll 110 of the present embodiment in an image forming apparatus, the conductive second adhesive layer 24 is in an electrically conductive state with the conductive core metal 10, and thus the entire elastic roll 110. As a result, the chargeability of the elastic roll 110 is not impaired. On the other hand, the charge transfer between the insulating first adhesive layer 22 and the surface of the conductive core 10 is, for example, conductive. Since it decreases compared to the transfer of charge between the adhesive layer and the surface of the conductive core metal, the occurrence of rust in the region where the first adhesive layer 22 of the conductive core metal 10 is formed due to the use history is suppressed, In the case of the present embodiment, the generation of shape distortion of the elastic layer 16 derived from rust is suppressed, and as a result, the entire surface of the elastic layer 16 is used as an image forming region.

  The extension region of the second adhesive layer 24 extending from the axial end portion of the first adhesive layer 22 can be arbitrarily set within a range in which a conductive state can be ensured, but it is elastic from the viewpoint of ensuring electrical conduction reliably. It is preferably 0.1% or more and 1% or less with respect to the axial length of the layer 16. For example, when the length of the elastic layer 16 in the axial direction is 300 mm, the extension region of the second adhesive layer 24 is not less than 0.3 mm and not more than 3 mm, preferably not less than 1 mm and not more than 2 mm. In addition, although it is preferable that the extension area | region of the 2nd contact bonding layer 24 exists in a roll both ends, only one side may be sufficient.

  The conductive cored bar 10, the first adhesive layer 22, the second adhesive layer 24, the elastic layer 16, and the surface layer material in the present embodiment are the conductive cored bar 10 described in the first embodiment, Since the same material as that of the first adhesive layer 12, the second adhesive layer 14, the elastic layer 16, and the surface layer is used, the thickness of the layers is the same, and the means for creating each layer is also the same. The description in is omitted.

As shown in FIG. 3, the elastic roll 120 of the second reference embodiment of the present invention has at least a concentric insulating first adhesive layer 12 on the outer periphery of the conductive core 10, and a conductive property. The second adhesive layer 14 and the semiconductive elastic layer 16 are laminated, and the conductive third adhesive layer 18 having an end extending from the axial end of the first adhesive layer 12. The second adhesive layer 14 and the third adhesive layer 18 are in contact with each other at least partially. Further, a surface layer (not shown) that is a resistance layer is laminated on the elastic layer 16. Furthermore, in the reference embodiment, as shown in FIG. 3, both end faces of the elastic layer 16 and both end faces of the first adhesive layer 12 are substantially flush with each other. In addition, about the structure same as the elastic roll in 1st reference embodiment and 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

The conductive third adhesive layer 18 in the reference embodiment is laminated so as to extend from the end portion of the first adhesive layer 12, and the third adhesive layer 18 is formed on the entire surface of the first adhesive layer 12. In consideration of the increase in the thickness of the elastic roll and the manufacturing cost, as shown in FIG. 3, one end portion of the third adhesive layer 18 comes into contact with the conductive metal core 10 and the third bonding is performed. The layer 18 is preferably laminated so that the other end of the layer 18 partially overlaps the end of the first adhesive layer 12. Further, in the present embodiment, since the entire outer periphery of the third adhesive layer 18 is bonded to a part of the inner peripheral surface of the second adhesive layer 14, the conductive metal core 10 and the elastic layer 16 are The third adhesive layer 18 and the second adhesive layer 14 are in a conductive state.

In the reference embodiment, since the current is supplied from the conductive third adhesive layer 18 to the entire elastic roll 120 from the non-image forming area of the elastic roll 120 through the conductive second adhesive layer 14, the charging performance is improved. There is no loss. Therefore, as described above, the first adhesion of the conductive metal core 10 in the elastic roll 120 having a history of use without impairing the adhesion, manufacturability, and charging performance between the conductive metal core 10 and the elastic layer 16. Rust generation in the image forming area where the layer 12 is formed is suppressed.

In the reference embodiment, the volume resistivity of the third adhesive layer 18 may be the same as that of the second adhesive layer 14 or either one may have a higher volume resistivity. The volume resistivity of the third adhesive layer 18 is preferably lower than the volume resistivity of the second adhesive layer 14. The volume resistivity 18 of the third adhesive layer is 1 × 10 ⁸ Ω · cm or less, preferably 1 × 10 ⁻¹ Ω · cm or more, preferably 1 × 10 ⁶ Ω · cm, by the same measurement method as described above. Or less, more preferably 1 × 10 ¹ Ω · cm or more and 1 × 10 ⁵ Ω · cm or less.

  The thickness of the third adhesive layer 18 is 1 μm or more and 30 μm or less, preferably 3 μm or more and 20 μm or less, and more preferably 5 μm or more and 15 μm or less.

  The extension region of the third adhesive layer 18 extending from the axial end portion of the first adhesive layer 12 can be arbitrarily set within a range in which a conductive state can be ensured, but it is elastic from the viewpoint of ensuring electrical conduction reliably. It is preferably 0.1% or more and 1% or less with respect to the axial length of the layer 16. For example, when the length of the elastic layer 16 in the axial direction is 300 mm, the extension region of the third adhesive layer 18 is not less than 0.3 mm and not more than 3 mm, preferably not less than 1 mm and not more than 2 mm. In addition, although it is preferable that the extension area | region of the 3rd contact bonding layer 18 exists in a roll both ends, only one side may be sufficient.

Elastic roll 130 of the third reference embodiment of the present invention, as shown in FIG. 4, the outer periphery of the conductive core metal 10, a first adhesive layer 22 of insulating at least coaxially, conductive The second adhesive layer 14 and the semiconductive elastic layer 16 are laminated, and the conductive third adhesive layer 28 having an end extending from the axial end of the first adhesive layer 22. The second adhesive layer 14 and the third adhesive layer 28 are in contact with each other at least partially. Further, a surface layer (not shown) that is a resistance layer is laminated on the elastic layer 16. Furthermore, in the reference embodiment, as shown in FIG. 3, both end faces of the elastic layer 16 and both end faces of the second adhesive layer 14 are substantially flush with each other. In addition, about the structure same as the elastic roll in 1st reference embodiment and 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

More specifically, the conductive third adhesive layer 28 in the reference embodiment has its entire inner surface in contact with the conductive core 10, while on the one end of the third adhesive layer 28. Are formed so that the end portions of the first adhesive layer 12 overlap each other. On the other hand, since the conductive second adhesive layer 12 is laminated so as to be in contact with the outer peripheral surface of the third adhesive layer 28 extending from the first adhesive layer 14, the conductive core 10 and the elastic layer are laminated. 16 is in a conductive state via the third adhesive layer 28 and the second adhesive layer 14.

In the reference embodiment, since the current is supplied from the conductive third adhesive layer 28 to the entire elastic roll 130 from the non-image forming area of the elastic roll 130 through the conductive second adhesive layer 14, the charging performance is improved. There is no loss. Therefore, as described above, the first direct contact with the conductive metal core 10 in the elastic roll 130 having a history of use is obtained without impairing the adhesiveness, manufacturability, and charging performance between the conductive metal core 10 and the elastic layer 16. The occurrence of rust in the image forming area where the adhesive layer 12 is adhered is suppressed.

In the reference embodiment, the volume resistivity of the third adhesive layer 28 may be the same as or higher than that of the second adhesive layer 14, but the volume resistivity may be higher than that of the conductive core 10. In consideration of adhesiveness and further suppression of rust generation, the volume resistivity of the third adhesive layer 28 is preferably higher than the volume resistivity of the second adhesive layer 14. The volume resistivity 28 of the third adhesive layer is 1 × 10 ⁸ Ω · cm or less, preferably 1 × 10 ¹ Ω · cm or more, preferably 1 × 10 ⁶ Ω · cm or less, by the same measurement method as described above. More preferably, it is 1 × 10 ¹ Ω · cm or more and 1 × 10 ⁵ Ω · cm or less.

  The film thickness of the third adhesive layer 28 is 1 μm or more and 30 μm or less, preferably 3 μm or more and 20 μm or less, and more preferably 5 μm or more and 15 μm or less.

  The extension region of the third adhesive layer 28 extending from the axial end portion of the first adhesive layer 12 can be arbitrarily set within a range in which a conduction state can be secured, but from the viewpoint of ensuring conduction, it is elastic. It is preferably 0.1% or more and 1% or less with respect to the axial length of the layer 16. For example, when the length of the elastic layer 16 in the axial direction is 300 mm, the extension region of the third adhesive layer 18 is not less than 0.3 mm and not more than 3 mm, preferably not less than 1 mm and not more than 2 mm.

The elastic roll 140 according to the second embodiment of the present invention is configured so that the end surface of the first adhesive layer 22 and the end surface of the elastic layer 16 are substantially flush, as shown in FIG. Except that the axial end of the third adhesive layer 18 and the axial end of the second adhesive layer 24 are formed extending from the axial end of the first adhesive layer 12, This is the same as the embodiment. In addition, about the structure same as the elastic roll in 1st, 2nd reference embodiment and 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  When image formation is performed using the elastic roll 140 of the present embodiment in an image forming apparatus, the second adhesive layer 24 is electrically connected to the conductive core 10 via the conductive third adhesive layer 18. Therefore, the current is supplied to the entire elastic roll 140, and as a result, the chargeability of the elastic roll 140 is not impaired, while the charge between the insulating first adhesive layer 22 and the surface of the conductive core 10 is not reduced. Is reduced compared to, for example, the transfer of electric charges between the conductive adhesive layer and the conductive core surface, so that the first adhesive layer 22 of the conductive core 10 based on the use history is formed. Generation of rust in the area is suppressed, and in the case of the present embodiment, generation of shape distortion of the elastic layer 16 derived from rust is suppressed, and as a result, the entire surface of the elastic layer 16 is used as an image forming area.

The elastic roll 150 according to the third embodiment of the present invention is configured such that the end surface of the first adhesive layer 22 and the end surface of the elastic layer 16 are substantially flush with each other, as shown in FIG. Except that the axial end of the third adhesive layer 28 and the axial end of the second adhesive layer 24 are formed extending from the axial end of the first adhesive layer 22, This is the same as the embodiment. In addition, about the structure same as the elastic roll in 1st, 2nd, 3rd reference embodiment and 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  When image formation is performed using the elastic roll 150 of the present embodiment in an image forming apparatus, the second adhesive layer 24 is electrically connected to the conductive core 10 via the conductive third adhesive layer 18. Therefore, the current is supplied to the entire elastic roll 150, and as a result, the chargeability of the elastic roll 150 is not impaired, while the charge between the insulating first adhesive layer 22 and the surface of the conductive core 10 is not reduced. For example, since the transfer is reduced as compared with the transfer of charge between the conductive adhesive layer and the conductive core surface, the first adhesive layer 22 of the conductive core 10 is directly formed according to the use history. In the present embodiment, the generation of rust in the elastic layer 16 derived from rust is suppressed, and as a result, the entire surface of the elastic layer 16 is used as the image forming region. As shown in FIG. 6, for example, when the elastic layer 16 is formed in a region smaller than the region where the first adhesive layer 12 is in direct contact with the conductive core metal 10, for example, under high temperature and high humidity. Even if rust is generated on the conductive core 10 that is used for a long time and is bonded to the third adhesive layer 28, the entire elastic layer 16 is secured as an image forming area.

As shown in FIG. 7, the elastic roll 160 of the fourth reference embodiment of the present invention has an electrically conductive first adhesive layer 22 at least concentrically formed on the outer periphery of the conductive metal core 10, and a conductive material. The second adhesive layer 14 and the semiconductive elastic layer 16 are laminated, and the conductive core 38 and the conductive layer 38 in contact with the end faces of the second adhesive layer 14 are further provided. In addition, about the structure same as the elastic roll in 1st, 2nd, 3rd reference embodiment and 1st, 2nd embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

In the reference embodiment, since the conductive layer 38 is electrically connected to the conductive core metal 10 and the conductive layer 38 is in contact with the end face of the conductive second adhesive layer 14, the elastic roll 160 as a whole. As a result, the charging property of the elastic roll 160 is not impaired, while the charge transfer between the insulating first adhesive layer 22 and the conductive core surface 10 is performed by the conductive adhesive layer. , And the surface of the conductive cored bar is reduced compared with the transfer of electric charge between the surfaces of the conductive cored bar and the occurrence of rust in the region where the first adhesive layer 22 of the conductive cored bar 10 is directly formed due to the use history is suppressed. In the case of this form, generation of shape distortion of the elastic layer 16 derived from rust is suppressed, and as a result, the entire surface of the elastic layer 16 is used as an image forming region.

The conductive layer 38 is known as long as it has high adhesiveness to the conductive metal core 10 and the second adhesive layer 14 and has a volume resistivity lower than that of the first adhesive layer 12. Any of these adhesives is used. As the conductive layer 38, for example, a layer mainly composed of an olefin resin, acrylic resin, epoxy resin, phenol resin, polyurethane resin, chlorinated rubber, chloroprene rubber, acrylonitrile-butadiene copolymer rubber, or the like is used. 38 contains conductive particles or semiconductive particles. Examples of the conductive particles or semiconductive particles include carbon black such as ketjen black and acetylene black, pyrolytic carbon, graphite, zinc, aluminum, copper, iron, nickel, chromium, titanium and other metals, ZnO-Al _{2 O 3, SnO 2 -Sb 2} O 3, In 2 O 3 -SnO 2, ZnO-TiO 2, MgO-Al 2 O 3, FeO-TiO 2, TiO 2, SnO 2, Sb 2 O 3, In 2 Metal oxides such as O ₃ , ZnO, and MgO are used, and these materials may be used alone or in admixture of two or more. As the adhesive used for the second adhesive layer 14, for example, a material obtained by adding a conductive agent (Ketjen Black EC: manufactured by Lion Corporation) to Chemlock 258 (manufactured by Road Far East) is used.

  In addition to the above, the conductive layer 38 is made of, for example, conductive grease in which carbon black is dispersed.

The volume resistivity of the conductive layer 38 is 1 × 10 ⁶ Ω · cm or less, preferably 1 × 10 ⁻³ Ω · cm or more and 1 × 10 ⁴ Ω · cm or less, more preferably 1 × 10 6. ⁻¹ Ω · cm or more and 1 × 10 ³ Ω · cm or less.

  The film thickness of the conductive layer 38 is 1 μm or more and 30 μm or less, preferably 3 μm or more and 20 μm or less, and more preferably 5 μm or more and 15 μm or less.

  The contact region between the conductive layer 38 and the conductive metal core 10 can be arbitrarily set within a range in which a conductive state can be ensured, but from the viewpoint of reliably ensuring electrical conduction, the length of the elastic layer 16 in the axial direction is It is 0.1% or more and 1% or less. For example, when the length of the elastic layer 16 in the axial direction is 300 mm, the contact area of the conductive layer 38 is not less than 0.3 mm and not more than 3 mm, preferably not less than 1 mm and not more than 2 mm. The contact area of the conductive layer 38 is preferably at both ends of the roll, but may be only on one side.

The elastic roll manufacturing method in the fourth reference embodiment described above has at least an insulating first adhesive layer 22, an electrically conductive second adhesive layer 14, on the conductive core 10 shown in FIG. A step of laminating and forming the semiconductive elastic layer 16 in sequence, a step of aligning both ends of the first adhesive layer 22, the second adhesive layer 14, and the elastic layer 16, the conductive core metal 10 and the second core Forming a conductive layer in contact with the end face of the adhesive layer.

  By the relatively simple process of providing the conductive layer 38 so as to be in contact with both the end face of the second adhesive layer 14 and the conductive core metal 10, the conductive core metal 10 and the second adhesion are bonded via the conductive layer 38. An elastic roll 160 that conducts the layer 14 is obtained. Furthermore, since the charge transfer between the insulating first adhesive layer 22 and the surface of the conductive core 10 is reduced compared to the charge transfer between the conductive adhesive layer and the surface of the conductive core, it is used. The occurrence of rust in the region where the first adhesive layer 22 of the conductive core 10 is directly formed due to the history is suppressed, and the generation of shape distortion of the elastic layer 16 derived from rust is suppressed. As a result, the elastic layer 16 The elastic roll 160 in which the entire surface is used as an image forming area is manufactured.

  FIG. 11 is an overall configuration diagram illustrating an example of an image forming apparatus according to the present embodiment.

  Next, an example of the image forming apparatus according to the present embodiment will be described.

  FIG. 11 is a schematic diagram illustrating a configuration example of an image forming apparatus using the elastic roll of the above-described embodiment as a charging roll. In the illustrated image forming apparatus 200, four electrophotographic photosensitive members 401 a to 401 d are disposed in parallel in the housing 400 along the intermediate transfer belt 409. The electrophotographic photoreceptors 401a to 401d form, for example, images in which the electrophotographic photoreceptor 401a is yellow, the electrophotographic photoreceptor 401b is magenta, the electrophotographic photoreceptor 401c is cyan, and the electrophotographic photoreceptor 401d is black. Is possible.

  Each of the electrophotographic photosensitive members 401a to 401d can be rotated in a predetermined direction (counterclockwise on the paper surface), and charging rolls 402a to 402d, which are elastic rolls, and developing devices 404a to 404d, 1 and 1 along the rotation direction. Next transfer rolls 410a to 410d and cleaning blades 415a to 415d are arranged. Each of the developing devices 404a to 404d can be supplied with toner of four colors of black, yellow, magenta and cyan accommodated in the toner cartridges 405a to 405d, and the primary transfer rolls 410a to 410d are respectively intermediate transfer belts. 409 is in contact with the electrophotographic photoreceptors 401a to 401d.

  Further, an exposure device 403 is disposed at a predetermined position in the housing 400, and it becomes possible to irradiate the surfaces of the charged electrophotographic photoreceptors 401a to 401d with a light beam emitted from the exposure device 403. ing. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photosensitive members 401a to 401d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 409 in an overlapping manner.

  Here, the charging rolls 402a to 402d are for contacting the surfaces of the electrophotographic photosensitive members 401a to 401d to uniformly apply a voltage to the photosensitive member to charge the surface of the photosensitive member to a predetermined potential (charging step). . As the charging rolls 402a to 402d, the elastic rolls 100, 110, 120, 130, 140, 150, 160 in the above-described embodiment are used.

  As the exposure apparatus 403, an optical system apparatus or the like that can expose a light source such as a semiconductor laser, an LED (light emitting diode), a liquid crystal shutter, or the like on the surfaces of the electrophotographic photosensitive members 401a to 401d can be used. Among these, when an exposure apparatus capable of exposing non-interference light is used, interference fringes between the electroconductive substrates of the electrophotographic photoreceptors 401a to 401d and the photosensitive layer can be prevented.

  As the developing devices 404a to 404d, a general developing device that develops the two-component electrostatic image developer in contact or non-contact with the developer can be used (developing step). Such a developing device is not particularly limited as long as a two-component electrostatic image developing developer is used, and a known one can be appropriately selected according to the purpose. In the primary transfer process, a primary transfer bias having a polarity opposite to that of the toner carried on the image carrier is applied to the primary transfer rolls 410a to 410d, so that each color toner is transferred from the image carrier to the intermediate transfer belt 409. The primary transfer is performed sequentially.

  The cleaning blades 415a to 415d are for removing residual toner adhering to the surface of the electrophotographic photosensitive member after the transfer process, and the electrophotographic photosensitive member cleaned by this cleaning process is repeatedly used in the above-described image forming process. Is done. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.

  The intermediate transfer belt 409 is supported with a predetermined tension by a driving roll 406, a back roll 408, and a tension applying roll 407, and can rotate without causing deflection due to the rotation of these rolls. The secondary transfer roll 413 is disposed so as to contact the back roll 408 via the intermediate transfer belt 409.

  By applying a secondary transfer bias having a reverse polarity to the toner on the intermediate transfer member to the secondary transfer roll 413, the toner is secondarily transferred from the intermediate transfer belt to the recording medium. The intermediate transfer belt 409 that has passed between the back roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed near the drive roll 406 or a static eliminator (not shown). It is repeatedly used for the next image forming process. Further, a paper feeding device (transfer medium container) 411 is provided at a predetermined position in the housing 400, and the medium to be transferred 500 such as paper in the paper feeding device 411 is connected to the intermediate transfer belt 409 by the transfer roll 412. After being sequentially transferred between the secondary transfer roll 413 and between the two fixing rolls 414 that are in contact with each other, the paper is discharged outside the housing 400. As the primary transfer rolls 410a to 410d and the secondary transfer roll 413, the elastic rolls 100, 110, 120, 130, 140, 150, and 160 in the above-described embodiments can be used.

  As shown in FIG. 11, the process cartridge according to the present embodiment uses the elastic roll of the above-described embodiment as a charging roll. The charging roll 402a, the electrophotographic photosensitive member 401a, and the cleaning blade 415a, which are elastic rolls, are used. The developing device 404a is integrated to form, for example, a black process cartridge. Similarly, a charging roll 402b that is an elastic roll, an electrophotographic photosensitive member 401b, a cleaning blade 415b, and a developing device 404b are integrated to form a yellow process cartridge, and the charging roll 402c that is an elastic roll, and the electrophotographic photosensitive member. The body 401c, the cleaning blade 415c, and the developing device 404c are integrated to form a magenta process cartridge. The charging roll 402d that is an elastic roll, the electrophotographic photosensitive member 401d, the cleaning blade 415d, and the developing device 404d are integrated. Thus, a cyan process cartridge is constructed.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “part” represents “part by mass”.

<Reference Example 1>
(Production of elastic roll)
An example of the configuration of the elastic roll 100 shown in FIG. 1 was manufactured.

-Formation of adhesive layer-
A Chemlock 607 (manufactured by Road Far East) having a thickness of 10 μm is left on the conductive core 10 of a free-cutting steel material treated with a cylindrical nickel plating having a diameter of 8 mm and a length of 332 mm, leaving both ends 10 mm. The first adhesive layer 12 was formed by coating. The volume resistivity of the first adhesive layer 12 was 1 × 10 ¹⁴ Ω · cm, and the resistance between the conductive core metal 10 and the first adhesive layer 14 was 1 × 10 ¹² Ω or more.

Next, a conductive material in which 5 parts by mass of a conductive agent (Ketjen Black EC: manufactured by Lion Corp.) is dispersed in 100 parts by mass of Chemlock 258 (manufactured by Road Far East Co., Ltd.) has the first adhesive layer 12 formed thereon. The second adhesive layer 14 was formed by coating the cored bar 10 so that both end portions were 8 mm and the film thickness was 15 μm. The volume resistivity of the second adhesive layer 14 was 1 × 10 ⁴ Ω · cm, and the resistance between the conductive core 10 and the second adhesive layer 14 was 2 × 10 ⁴ Ω.

(Measurement of volume resistivity)
In the examples and comparative examples, the volume resistivity of the adhesive layer was measured by using a gap gauge on an aluminum material of 100 mm × 100 mm and a thickness of 2 mm to form a 10 μm coating liquid film as a sample.

  For the measurement, a circular electrode (Hiresta UPMCP-450 type UR probe manufactured by Dia Instruments Co., Ltd.) and a high resistance measuring device (manufactured by Advantest, R8340A digital high resistance / microammeter) are used. JIS K 6911 (1995) Measured according to Specifically, as a measurement condition, a voltage of 5 V was applied in an environment of 25 ° C. and 55% RH, a current after 10 seconds was obtained, and calculated by the following formula (1).

Formula (1): Calculated from volume resistivity ρv = 19.6 × (V / I) × t.
(In formula (1), t represents the thickness of the adhesive layer.)

(Measurement of resistance between conductive core and adhesive layer)
In Examples and Comparative Examples, the resistance between the conductive metal core and the adhesive layer is an average value of values measured by the method described in JP-A-6-118105.

  The average value of the resistance is based on the resistance value measured by the following method. In the axial direction, 20 mm from the both ends of the adhesive layer on the conductive core metal, 3 points in the center, and 3 In the direction, resistance was measured every 6 degrees, and all measured values were obtained by arithmetic averaging.

  In this resistance measurement, an electrode made of a cylindrical SUS bearing having a width of 5 mm was used as an electrode, and this electrode was brought into contact with the adhesive layer to be measured with a load of 25 g, and the roll was placed in an environment of 25 ° C. and 55% RH. While rotating at 5.5 rpm, the current at an applied voltage of 1 V was measured between the resistance measurement electrode and the conductive core at every angle of 6 degrees, and the resistance was calculated by the following formula (2).

At this time, a high resistance measuring instrument (manufactured by Advantest, R8340A digital high resistance / microammeter) was used as the power source and ammeter.
Formula (2): Resistance (Ω) = Applied voltage (V) / Current (A)

-Formation of elastic layer-
In order to form the elastic layer 16, the following mixture is kneaded with an open roll, and the thickness is 3 mm, leaving both ends 8 mm on the conductive core 10 on which the first adhesive layer 12 and the second adhesive layer 14 are formed. It is coated in a cylindrical shape so as to become, put into a cylindrical mold having an inner diameter of 14.0 mm, vulcanized at 170 ° C. for 30 minutes, taken out from the mold, polished, and the thickness of the central part is the end part. A cylindrical elastic layer having a thickness less than that of the above was obtained. The difference in the outer diameter between the central portion and the end portion was 85 μm.
・ Rubber material: 100 parts by mass (Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber: Gechron 3106: manufactured by Nippon Zeon Co., Ltd.)
-Conductive agent (Carbon Black Asahi Thermal: manufactured by Asahi Carbon Co., Ltd.) ... 15 parts by mass-Ionic conductive agent (lithium perchlorate)-1 part by mass-Vulcanizing agent (sulfur) 200 mesh: Tsurumi Chemical Co., Ltd. Product: 1 part by mass, vulcanization accelerator (Noxeller DM: manufactured by Ouchi Shinsei Chemical Co., Ltd.) ... 2.0 parts by mass: Vulcanization accelerator (Noxeller TT: manufactured by Ouchi New Chemical Co., Ltd.) ..0.5 parts by mass

-Formation of surface layer-
In order to form a resistance layer on the elastic layer 16, a dispersion obtained by dispersing the following mixture with a bead mill was diluted with methanol to obtain a coating solution for the resistance layer. This coating solution was applied to the surface of the elastic layer by a dip coating method, and then heated and dried at 150 ° C. for 15 minutes to form a 10 μm resistance layer, whereby an elastic roll 100 was obtained.
-Polymer material (copolymer nylon) Alamine CM8000: 100 parts by mass manufactured by Toray Industries, Inc.-Conductive agent (carbon black) MONARCH1000: 12 parts by mass manufactured by Cabot Corporation-Solvent (methanol) 500 parts by mass-Solvent (butanol) 240 parts by mass

<Example 1>
(Production of elastic roll)
An example of the configuration of the elastic roll 110 shown in FIG. 2 was manufactured. Except for applying the first adhesive layer 22 leaving both ends 8 mm of the conductive core 10 and applying the second adhesive layer 24 leaving both ends 7 mm of the conductive core 10, the first adhesive layer and the second adhesive layer using the same material, in the same manner as in reference example 1 to obtain an elastic roll 110 of the embodiment shown in FIG. Here, the volume resistivity of the first adhesive layer 12 is 1 × 10 ¹⁴ Ω · cm, and the resistance between the conductive core metal 10 and the first adhesive layer 14 is 1 × 10 ¹² Ω or more. there were. The volume resistivity of the second adhesive layer 14 was 1 × 10 ⁴ Ω · cm, and the resistance between the conductive core metal 10 and the second adhesive layer 14 was 2 × 10 ⁶ Ω.

< Reference Example 2 >
(Production of elastic roll)
After forming to the 1st contact bonding layer 12 similarly to the reference example 1, 3 mass parts of electrically conductive agents (Ketjen Black EC: product made from Lion Corporation) were disperse | distributed to 100 mass parts of Chemlock 204 (product made from a load far east company). The liquid was applied only to 8 mm to 11 mm at both ends so as to have a film thickness of 10 μm to form the third adhesive layer 18. Then, except having formed the 2nd adhesion layer 14 like Example 1, the following was formed according to Reference Example 1, and elastic roll 120 of the mode shown in Drawing 3 was obtained. Here, the volume resistivity of the third adhesive layer 18 is 1 × 10 ⁵ Ω · cm, which is higher than the volume resistivity of the second adhesive layer 14, and the conductive core metal 10 and the second adhesive layer 14. The resistance in between was 5 × 10 ⁶ Ω.

< Reference Example 3 >
(Production of elastic roll)
First, a solution in which 3 parts by mass of a conductive agent (Ketjen Black EC: manufactured by Lion Corporation) is dispersed in 100 parts by mass of Chemlock 204 (manufactured by Road Far East) has a film thickness of 10 μm only at 8 to 11 mm at both ends. After forming the third adhesive layer 28, the first adhesive layer 12 is applied by applying Chemlock 607 (manufactured by Road Far East Co., Ltd.) to a thickness of 10 μm, leaving both end portions 10 mm. Formed. Thereafter, except for forming the second adhesive layer 14 in the same manner as in Reference Example 1, in accordance with Reference Example 1, to form a later to obtain an elastic roll 130 of the embodiment shown in FIG. Here, the volume resistivity of the third adhesive layer 28 is higher than the volume resistivity of the second adhesive layer 14, which is 1 × 10 ⁵ Ω · cm, and the conductive core metal 10 and the second adhesive layer 14. The resistance in between was 5 × 10 ⁶ Ω.

<Example 2 >
(Production of elastic roll)
After forming up to the first adhesive layer 22 in the same manner as in Example 1 , 3 parts by mass of a conductive agent (Ketjen Black EC: manufactured by Lion Corporation) was dispersed in 100 parts by mass of Chemlock 204 (manufactured by Road Far East). The liquid was applied only to 7 mm to 9 mm at both ends so as to have a film thickness of 10 μm to form a third adhesive layer 18. Thereafter, except for forming the second adhesive layer 24 in the same manner as in Example 1, in accordance with Example 1, to form a later to obtain an elastic roll 140 of the embodiment shown in FIG. Here, the volume resistivity of the third adhesive layer 18 is 1 × 10 ⁵ Ω · cm, which is lower than the volume resistivity of the second adhesive layer 24, and the conductive core metal 10 and the second adhesive layer 24. The resistance in between was 5 × 10 ⁶ Ω.

<Example 3 >
(Production of elastic roll)
As in Reference Example 3 , a solution in which 3 parts by mass of a conductive agent (Ketjen Black EC: manufactured by Lion Corporation) was dispersed in 100 parts by mass of Chemlock 204 (manufactured by Road Far East) was applied only from 7 mm to 9 mm at both ends. After coating to a thickness of 10 μm to form the third adhesive layer 28, Chemlock 607 (manufactured by Road Far East) is applied to a thickness of 8 μm, leaving 10 mm at both ends. The adhesive layer 22 was formed. Thereafter, except for forming the second adhesive layer 24 in the same manner as in Reference Example 3, according to Reference Example 3, to form a later to obtain an elastic roll 150 of the embodiment shown in FIG. Here, the volume resistivity of the third adhesive layer 28 is higher than the volume resistivity of the second adhesive layer 14, which is 1 × 10 ⁵ Ω · cm, and the conductive core metal 10 and the second adhesive layer 14. The resistance was 5 × 10 ⁶ Ω.

< Reference Example 4 >
(Production of elastic roll)
A Chemlock 607 (manufactured by Road Far East) having a thickness of 10 μm is left on the conductive core 10 of a free-cutting steel material treated with a cylindrical nickel plating having a diameter of 8 mm and a length of 332 mm, leaving both ends 10 mm. It applied so that the 1st adhesion layer 12 might be formed. The volume resistivity of the first adhesive layer 12 was 1 × 10 ¹⁴ Ω · cm, and the resistance between the conductive metal core 10 and the first adhesive layer 14 was 1 × 10 ¹² Ω or more.

Next, a liquid in which 5 parts by mass of a conductive agent (Ketjen Black EC: manufactured by Lion Corporation) is dispersed in 100 parts by mass of Chemlock 258 (manufactured by Road Far East Co., Ltd.) is left to leave the both ends 10 mm of the conductive core 10 The second adhesive layer 14 was formed by coating to a thickness of 15 μm. The volume resistivity of the second adhesive layer 14 was 1 × 10 ⁴ Ω · cm.

Next, after forming the elastic layer 16 in the same manner as in Example 1 , the elastic layer 16 was cut and removed at a position 9 mm from both end faces of the cored bar to expose the end face of the second adhesive layer 14. Next, a liquid obtained by dispersing 10 parts by mass of a conductive agent (Ketjen Black EC: manufactured by Lion Corporation) in 100 parts by mass of Chemlock 204 (manufactured by Road Far East) as the conductive layer 38 is used as a conductive core 10 and The adhesive layer 14 was applied in contact with the second adhesive layer 14. Then, the surface layer was formed similarly to the reference example 1, and the elastic roll 160 of the aspect shown in FIG. 7 was obtained. Here, the volume resistivity of the conductive layer 38 was 1 × 10 ¹ Ω · cm.

< Reference Example 5 >
(Production of elastic roll)
According to Example 7, another embodiment of the elastic roll 170 shown in FIG. 7 was obtained except that the conductive layer 38 of Reference Example 4 was replaced with conductive grease in which carbon black was dispersed. Here, the volume resistivity of the conductive layer 38 made of conductive grease was 1 × 10 ¹ Ω · cm.

<Comparative Example 1>
(Production of elastic roll)
Except that the first adhesive layer 22 was applied leaving 8 mm of both ends of the conductive core metal, and the second adhesive layer 14 was applied so as not to directly touch the conductive core metal 10 leaving both ends of the core metal 9 mm. It created similarly to the reference example 1, and obtained the elastic roll 170 of the aspect shown in FIG. The elastic roll 170 was attached to a DocuCenter Color a450 manufactured by Fuji Xerox Co., Ltd., and a printing test was performed under low temperature and low humidity conditions (10 ° C., RH 15%) as in Reference Example 1 based on the evaluation described later. Because of poor charging, good image quality could not be obtained. Therefore, subsequent evaluation was not possible.

<Comparative example 2>
(Production of elastic roll)
The first adhesive layer 22 was produced in the same manner as in Reference Example 1 except that the second adhesive layer was not applied after the conductive cored bar 10 was applied except for both ends 8 mm, and the embodiment shown in FIG. An elastic roll 180 was obtained. This elastic roll was attached to DocuCenter Color a450 manufactured by Fuji Xerox Co., Ltd., and based on the evaluation described later, a print test was performed under the low temperature and low humidity conditions (10 ° C., RH 15%) as in Reference Example 1. A good image quality could not be obtained due to the defect. Therefore, subsequent evaluation was not possible.

<Comparative Example 3>
(Production of elastic roll)
Except not having applied the 1st contact bonding layer, it produced similarly to the reference example 1, and obtained the elastic roll 190 of the aspect shown in FIG.

[Evaluation]
(Image evaluation)
The above-mentioned elastic roll was attached in place of the charging roll of DocuCenter Color a450 manufactured by Fuji Xerox Co., Ltd., and a printing test was performed under low temperature and low humidity conditions (10 ° C., RH 15%). Next, print 10,000 sheets, and store the drum cartridge after printing 10,000 sheets in an environment of 40 ° C and 95% for 7 days, and then perform a print test under low temperature and low humidity conditions (10 ° C, RH15%). It was. Thereafter, the appearance of the elastic roll was further visually inspected.

The evaluation criteria for the print test are as follows.
○: No toner fog due to poor charging, no density increase, and no image quality defect.
X: Toner fog due to poor charging, density increase, and image quality defect.

(Degree of diameter expansion at both ends of the elastic roll)
<Measurement method>
The degree of diameter expansion at the end of the elastic roll is measured by measuring the outer diameter at 5 mm and 20 mm from the elastic layer end of the elastic roll with a laser-type outer diameter measuring device. It calculated | required from the value which pulled the outer diameter.

<Evaluation criteria>
The difference in outer diameter is good when the outer diameter difference is 10 μm or less, and ◯ is 10 to 20 μm, because there is a tendency to increase the diameter, but it is Δ, and when it is 20 μm or more, uneven wear of the photoreceptor due to uneven density or uneven discharge. Was generated.

  The results are shown in Tables 1 and 2.

< Reference Example 6 >
A stainless steel shaft having a diameter of 14 mm and a length of 306 mm was prepared as the conductive core 10. The joint surface to be bonded to the elastic layer of the conductive core metal 10 surface, Reference Example 1 and forming a first adhesive layer and second adhesive layer having the structure of FIG. 1 as well, and the resistance value was measured. The volume resistivity of the first adhesive layer 12 was 1 × 10 ¹⁴ Ω · cm, and the resistance between the conductive metal core 10 and the first adhesive layer 14 was 1 × 10 ¹² Ω or more. The volume resistivity of the second adhesive layer 14 was 1 × 10 ⁴ Ω · cm, and the resistance between the conductive core metal 10 and the second adhesive layer 14 was 2 × 10 ⁴ Ω.

  Next, 50 parts by mass of epichlorohydrin rubber (Gechron 3106: manufactured by Nippon Zeon Co., Ltd.), 50 parts by mass of NBR (DN4050, manufactured by Nippon Zeon Co., Ltd.), and 6 parts by mass of benzenesulfonylhydrazide as a foaming agent were mixed to obtain a mixture.

  Next, the above mixture was extruded on the outer periphery of the previously prepared conductive core 10 by a crosshead extruder, and an unfoamed rubber layer having an outer diameter of φ20 mm was formed leaving both end portions 8 mm. Next, the unfoamed rubber layer was vulcanized with a vulcanizing can at 160 ° C. for 20 minutes to be foamed to form a foamed rubber layer (elastic layer). The surface of this foamed rubber layer (elastic layer) was polished with a grinder to obtain an elastic roll (transfer roll 1) having an outer diameter of φ28 mm and having an elastic layer around the core.

<Example 4 >
(Production of elastic roll)
An example of the configuration of the elastic roll 110 shown in FIG. 2 was manufactured. Except for applying the first adhesive layer 22 leaving both ends 8 mm of the conductive core 10 and applying the second adhesive layer 24 leaving both ends 7 mm of the conductive core 10, the first adhesive layer and The same material was used for the second adhesive layer, and an elastic roll (transfer roll 2) having the form shown in FIG. Here, the volume resistivity of the first adhesive layer 12 is 1 × 10 ¹⁴ Ω · cm, and the resistance between the conductive core metal 10 and the first adhesive layer 14 is 1 × 10 ¹² Ω or more. there were. The volume resistivity of the second adhesive layer 14 was 1 × 10 ⁴ Ω · cm, and the resistance between the conductive core metal 10 and the second adhesive layer 14 was 2 × 10 ⁶ Ω.

[Evaluation]
(Image evaluation)
The elastic rolls of Reference Example 6 and Example 4 were attached in place of the secondary transfer roll of DocuColor 5065P manufactured by Fuji Xerox Co., Ltd., and a printing test was performed under low temperature and low humidity conditions (10 ° C., RH 15%). Next, print 10,000 sheets, and store the drum cartridge after printing 10,000 sheets in an environment of 40 ° C and 95% for 7 days, and then perform a print test under low temperature and low humidity conditions (10 ° C, RH15%). It was. Thereafter, the appearance of the elastic roll was further visually inspected.

The evaluation criteria for the print test are as follows.
○: No toner fog due to poor charging, no density increase, and no image quality defect.
X: Toner fog due to poor charging, density increase, and image quality defect.

(Degree of diameter expansion at both ends of the elastic roll)
<Measurement method>
The degree of diameter expansion at the end of the elastic roll is measured by measuring the outer diameter at 5 mm and 20 mm from the elastic layer end of the elastic roll with a laser-type outer diameter measuring device. It calculated | required from the value which pulled the outer diameter.

<Evaluation criteria>
The difference in outer diameter is good when the outer diameter difference is 10 μm or less, and ◯ is 10 to 20 μm, because there is a tendency to increase the diameter, but it is Δ, and when it is 20 μm or more, uneven wear of the photoreceptor due to uneven density or uneven discharge. Was generated.

  The results are listed in Table 1 above.

  In Examples 1 to 9, the initial printing test, the image quality after storage after the printing test for 10,000 sheets, and the appearance inspection result were good. However, in Example 1, Example 3 and Example 4, although rust was seen in a part of the end, only rust was seen in the non-image area, so this was not a practical problem. . On the other hand, in Comparative Example 1, since the second adhesive layer was not in electrical contact with the conductive core, the photoconductor could not be charged. In Comparative Example 2, the photoconductor could not be charged because there was no second adhesive layer. Further, in Comparative Example 3, since there is no first adhesive layer, the image quality is deteriorated after storage after the 10,000-sheet printing test, and shape deformation due to corrosion of the core metal is recognized from the appearance inspection. .

  As an application example of the present invention, there is application to an image forming apparatus such as a copying machine or a printer using an electrophotographic system.

It is a cross-sectional view which shows an example of a structure of the elastic roll of 1st reference embodiment in this invention. It is a cross-sectional view which shows an example of a structure of the elastic roll of 1st Embodiment in this invention. It is a cross-sectional view which shows an example of a structure of the elastic roll of 2nd reference embodiment in this invention. It is a cross-sectional view which shows an example of a structure of the elastic roll of 3rd reference embodiment in this invention. It is a cross-sectional view which shows an example of a structure of the elastic roll of 2nd Embodiment in this invention. It is a cross-sectional view which shows an example of a structure of the elastic roll of 3rd Embodiment in this invention. It is a cross-sectional view which shows an example of a structure of the elastic roll of 4th reference embodiment in this invention. 6 is a cross-sectional view illustrating an example of a configuration of an elastic roll of Comparative Example 1. FIG. It is a cross-sectional view which shows an example of a structure of the elastic roll of the comparative example 2. It is a cross-sectional view which shows an example of a structure of the elastic roll of the comparative example 3. 1 is a schematic diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. It is a figure explaining the measuring method of resistivity.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Conductive metal core, 12, 22 1st adhesive layer, 14, 24 2nd adhesive layer, 16 Elastic layer, 18, 28 3rd adhesive layer, 38 Conductive layer, 100, 110, 120, 130, 140 , 150, 160 Elastic roll.

Claims (4)

On the conductive mandrel, at least an insulating first adhesive layer, a conductive second adhesive layer, and a semiconductive elastic layer are laminated in this order.
The second adhesive layer is in an electrically conductive state with the conductive core;
And the axial end of the second adhesive layer is formed extending from the axial end of the first adhesive layer and the axial end of the elastic layer,
Furthermore, it has a third adhesive layer that is conductive and has a volume resistivity lower than that of the second adhesive layer, and has an end extending from the axial end of the first adhesive layer,
The third adhesive layer is at least partially in contact with the conductive core metal and the second adhesive layer .
Elastic roll you, characterized in that. A charging device comprising the elastic roll according to claim 1 . A process cartridge comprising the elastic roll according to claim 1 . At least an image holding member, an image forming apparatus, characterized in that it comprises an elastic roll according to claim 1 in contact with the image holding member to charge the surface.

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