JP5407202B2 - Conductive roll, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a conductive roll, a process cartridge, and an image forming apparatus.

  In an image forming apparatus using an electrophotographic method, generally, a laser beam or the like that modulates an image signal by forming a charge on an image carrier composed of a photoconductive photoreceptor using an inorganic material or an organic material. After forming the electrostatic latent image, the electrostatic latent image is developed with toner to obtain a visualized toner image. Then, a desired reproduced image can be obtained by electrostatically transferring the obtained toner image to a recording medium such as recording paper via an intermediate transfer member.

For example, in a case where a toner image formed on an image carrier is primarily transferred to an intermediate transfer member and the toner image on the intermediate transfer member is secondarily transferred to a recording paper, the conductive or semiconductive (volume) 2. Description of the Related Art There is known a conductive roll type image forming apparatus in which a recording sheet is pressed against an intermediate transfer member using a conductive roll having a resistivity of 10 ¹⁰ Ωcm or less, and a toner image is electrostatically transferred by applying a voltage. ing.

  As the conductive roll, for example, an acrylic emulsion in which conductive carbon black is dispersed is impregnated with urethane slab foam, dried by heating, processed into a cylindrical shape of a desired size, and coated with an adhesive. There has been proposed a conductive roll in which is inserted into a central hole and bonded (for example, see Patent Document 1).

JP-A-9-262912

  An object of the present invention is to provide a conductive roll with reduced resistance unevenness even when the foamed elastic layer has orientation in the shape of the bubbles.

  In order to achieve the above object, the present invention provides the following conductive roll, process cartridge, and image forming apparatus.

The invention according to claim 1 is a conductive roll including a conductive support, and a foamed elastic layer having conductivity bonded to the entire periphery of the conductive support through an adhesive layer having conductivity. The foamed elastic layer has an orientation of bubbles in one direction perpendicular to the axial direction of the conductive support, and the adhesive layer has at least two types of adhesive layers having different electrical conductivity. When one of the longitudinal directions of the foamed elastic layer is defined as a 0 ° position in the circumferential direction of the conductive roll as viewed from the axial direction of the conductive roll, at least − A first adhesive layer is provided at positions 20 ° to 20 ° and 160 ° to 200 °, and a second adhesive layer is provided at least at positions 70 ° to 110 ° and 250 ° to 290 °; the first adhesive layer, conductive than said second adhesive layer Sex rather low, the conductivity of the first adhesive layer and the second region other than the adhesive layer of said adhesive layer are the same or these with any of the first adhesive layer and said second adhesive layer It is an electroconductive roll characterized by being between .

  The invention according to claim 2 is the conductive roll according to claim 1, wherein the first adhesive layer has ionic conductivity, and the second adhesive layer has electronic conductivity. .

  In the invention according to claim 3, the first adhesive layer and the second adhesive layer contain the same conductive agent, and the content of the conductive agent in the first adhesive layer is the second adhesive layer. The conductive roll according to claim 1, wherein the conductive roll is less than the content of the conductive agent.

  The invention according to claim 4 is the conductive roll according to claim 1, wherein the thickness of the first adhesive layer is larger than the thickness of the second adhesive layer.

  The invention according to claim 5 is the conductive roll according to any one of claims 1 to 4, wherein the foamed elastic layer is urethane foam.

  The invention according to claim 6 is characterized in that the foamed elastic layer is imparted with conductivity by forming a polymer containing a conductive substance on a wall surface of a cell of the foamed elastic layer. It is an electroconductive roll of any one of Claims 1-5.

  A seventh aspect of the present invention is a process cartridge comprising the conductive roll according to any one of the first to sixth aspects.

  An invention according to an eighth aspect is an image forming apparatus comprising the conductive roll according to any one of the first to sixth aspects.

According to the first aspect of the present invention, even when the foamed elastic layer has orientation in the shape of the bubbles, the resistance unevenness is alleviated as compared with the case without this configuration.
According to the second aspect of the present invention, it is possible to obtain a conductive roll in which resistance unevenness is more reliably alleviated than in the case where the present configuration is not provided.
According to the invention of claim 3, it is possible to obtain a conductive roll in which unevenness in resistance is more reliably alleviated than in the case where this configuration is not provided.
According to the invention of claim 4, it is possible to obtain a conductive roll in which uneven resistance is more reliably mitigated than in the case where the present configuration is not provided.
According to the invention of claim 5, while the bubbles of the foamed elastic layer have the orientation more surely, a conductive roll in which the resistance unevenness is more relaxed can be obtained as compared with the case without this configuration.
According to the invention of claim 6, a conductive roll more suitable for the image forming apparatus can be obtained as compared with the case where this configuration is not provided.
According to the seventh aspect of the present invention, it is possible to obtain a process cartridge that is less likely to cause image density unevenness as compared with the case without the present configuration.
According to the eighth aspect of the invention, it is possible to obtain an image forming apparatus that is less likely to cause density unevenness of the image as compared with the case where the present configuration is not provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding elements (members) are denoted by the same reference numerals, and redundant description is omitted.

The present inventors have studied and examined the density unevenness of an image generated in the image forming apparatus, and obtained the following knowledge.
For example, if a urethane slab having anisotropy (orientation) in the shape of foam cells (bubbles) is processed into a cylindrical shape and a core metal is bonded to the center hole to produce a conductive roll (bias roll), foaming Due to the orientation of the cells, a high resistance portion and a low resistance portion are formed in the circumferential direction of the foamed elastic layer, and relatively large in-plane resistance unevenness is likely to occur in the range of about 0.1 to 0.8 logΩ. If such a conductive roll continues to be used as a transfer roll of an image forming apparatus, the resistance increases at a different ratio between the high resistance portion and the low resistance portion of the conductive roll (foamed elastic layer), and the high resistance portion The resistance difference of the low resistance portion increases to 1.0 logΩ or more. As a result of the increase in the resistance difference in the circumferential direction of the conductive roll in this way, density unevenness of the image occurs.
Therefore, the present inventors have divided the low resistance portion and the high resistance portion of the foamed elastic layer according to the difference in conductivity caused by the orientation of the shape of the bubbles contained in the foamed elastic layer. Between the low-resistance part of the foamed elastic layer and the core metal, and the high-resistance part of the foamed elastic layer and the core metal. It has been found that by making the resistance higher than the resistance of the adhesive layer to be bonded, the resistance (conductivity) of the entire roll can be made uniform, and the occurrence of density unevenness in the image can be effectively suppressed.

  Furthermore, the present inventors alleviate the difference in resistance between the low resistance portion and the high resistance portion of the foamed elastic layer by making the thickness of the adhesive of the low resistance portion larger than the thickness of the adhesive of the high resistance portion. It has been found that in-plane unevenness of roll resistance is reduced and the occurrence of uneven volume resistance of the roll during use is suppressed.

  FIG. 1 is a schematic view of a conductive roll according to the present embodiment, and FIG. 2 is a schematic view showing a cross section taken along line AA of FIG. In the conductive roll 10, a foamed elastic layer 14 having conductivity is provided around a conductive support 12. And the shape (bubble diameter) of many bubbles 18 in the foamed elastic layer 14 has orientation, and the conductive support 12 and the foamed elastic layer 14 have two types of adhesive layers 16a, By adhering via 16b, the difference in conductivity of the foamed elastic layer 14 due to the orientation of the bubbles 18 is suppressed (reduced).

<Conductive support>
The conductive support 12 functions as an electrode and a support member of the conductive roll 10, and is a rod-shaped member, preferably a columnar or cylindrical member having an outer diameter in the range of 3 to 20 mm. Is used. Such a conductive support 12 is made of, for example, a metal or an alloy such as aluminum, a copper alloy, or stainless steel; iron subjected to a plating treatment with chromium, nickel, etc .; a conductive resin; Or a conductive material (volume resistivity is 10 ⁴ Ωcm or less).

<Foamed elastic layer>
The foamed elastic layer 14 has conductivity, and is formed with a large number of bubbles (cells) 18 having orientation. For example, a foamed elastic layer 14 having conductivity is formed by foaming an elastic material to form a cell skeleton and dispersing a conductive agent in the cell skeleton. The cell structure of the foamed elastic layer 14 may be a closed cell structure or an open cell structure.
For example, when the conductive roll 10 according to the present embodiment is used as a transfer roll, for example, the foamed elastic layer 14 is restored to its original shape even if it is deformed by applying an external force of 100 Pa. What forms a suitable contact area in the contact position with other members, such as a body, is preferable.

Specific materials for forming the cell skeleton of the foamed elastic layer 14 include epichlorohydrin, polyurethane, nitrile rubber, isoprene rubber, butadiene rubber, epichlorohydrin-ethylene oxide rubber, ethylene-propylene-diene rubber (EPDM), Styrene-butadiene rubber (SBR), chlorinated polyisoprene, acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), hydrogenated polybutadiene, butyl rubber, silicone rubber, or a material obtained by blending two or more of these materials Can be mentioned. Desirable are polyurethane, nitrile rubber, epichlorohydrin-ethylene oxide rubber, ethylene-propylene-diene rubber (EPDM), and more desirably polyurethane.
The polyurethane is not particularly limited, and polyols such as polyester polyol, polyether polyester and acrylic polyol, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, and tolidine. It only needs to be accompanied by a reaction of an isocyanate such as diisocyanate or 1,6-hexamethylene diisocyanate, and a chain extender such as 1,4-butanediol or trimethylolpropane is preferably mixed.

The foaming agent is generally foamed using a foaming agent such as water, azodicarbonamide, azobisisobutyronitrile, azo compounds such as diazoaminobenzene, etc. Examples thereof include bicarbonates such as sodium hydrogen carbonate that generate carbon dioxide by thermal decomposition, mixtures of NaNO ₂ and NH ₄ Cl that generate nitrogen gas, peroxides that generate oxygen and the like. Furthermore, you may add auxiliary agents, such as a foaming aid, a foam stabilizer, a catalyst, as needed.
For example, when a foaming agent or the like is added to polyurethane and foamed, when the urethane foam expands in the vertical direction, the bubbles (foamed cells) 18 also extend in the vertical direction to have a shape having a substantially elliptical cross section. (Bubble diameter) is oriented.

The conductive agent contained in the foamed elastic layer 14 is not particularly limited and may be appropriately selected depending on the application. For example, an electronic conductive agent or an ionic conductive agent is used.
Examples of the electronic conductive agent include carbon black such as furnace black, thermal black, channel black, ketjen black, acetylene black, and color black; pyrolytic carbon; graphite; various metals such as aluminum, copper, nickel, and stainless steel; Alloys; various metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, tin oxide-indium oxide solid solution; and the like. it can. Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium; perchlorates and chlorates of alkaline earth metals ;

  These conductive agents may be used alone or in combination of two or more. Moreover, there is no restriction | limiting in particular in the addition amount of a electrically conductive agent, What is necessary is just to make it contain a electrically conductive agent so that it may have desired electroconductivity according to the use of the conductive roll 10. FIG. For example, when the conductive roll 10 according to this embodiment is used as a transfer roll in an image forming apparatus, the content of the conductive agent in the foamed elastic layer 14 is an elastic material that forms a cell skeleton when an electronic conductive agent is used. The range is from 1 to 30 parts by mass with respect to 100 parts by mass, and more preferably from 10 to 20 parts by mass. On the other hand, when using an ionic conductive agent, it is the range of 0.1-5.0 mass parts with respect to 100 mass parts of elastic materials, and it is more desirable that it is the range of 0.5-3.0 mass parts.

The volume resistance value of the foamed elastic layer 14 of the conductive roll 10 according to this embodiment is such that the conductive roll 10 is placed on the surface of a metal plate such as a copper plate so that a load of 100 g is applied to both ends of the roll. When a voltage of 100 V is applied between the ^two, a range of 10 ² Ω to 10 ⁷ Ω is desirable, and a range of 10 ² Ω to 10 ⁶ Ω is more desirable.
The volume resistivity can be measured, for example, on a sheet-like measurement sample by using a measurement jig (R12702A / B resiliency chamber: manufactured by Advantest) and a high resistance measuring device (R8340A digital high resistance / microammeter: Advantest). And a voltage adjusted so that the electric field (applied voltage / composition sheet thickness) is 1000 V / cm is calculated from the current value after application for 30 seconds using the following formula (1).
Volume resistivity (Ω · cm) = (19.63 × applied voltage (V)) / (current value (A) × measurement sample sheet thickness (cm)) (1)
The electrical resistance around the conductive roll 10 can be measured, for example, by placing the conductive roll 10 on the surface of a metal plate such as a copper plate so that equal loads are applied to both ends of the roll. Measurement is performed by applying a voltage of 100 V between a conductive roll (core metal in the case of having a metal core) and the metal plate.

  The thickness of the foamed elastic layer 14 is desirably in the range of 2 to 7 mm, and more desirably in the range of 3 to 5 mm. When the thickness of the foamed elastic layer 14 is 2 mm or more, it is sufficiently deformed by the contact pressure at the contact portion with another member such as an intermediate transfer member, and the contact portion is stably formed. Further, if the thickness of the foamed elastic layer 14 is 7 mm or less, the resistance difference of the foamed elastic layer 14 is reliably reduced by separately applying the adhesive described later.

<Adhesive layer>
In the conductive roll 10 according to this embodiment, the conductive support 12 and the foamed elastic layer 14 have different conductivity so as to suppress the difference in conductivity of the foamed elastic layer 14 due to the orientation of the bubbles 18. It adhere | attaches through the kind of adhesion layers 16a and 16b. As shown in FIG. 2, the foamed elastic layer 14 has a cell shape (cell diameter) oriented as viewed from the axial direction of the conductive roll 10. Thus, when the shape (diameter) of the bubbles 18 in the foamed elastic layer 14 has orientation, a high resistance portion and a low resistance portion usually appear at 90 ° intervals. Specifically, when one of the longitudinal directions of the bubbles 18 (L direction in FIG. 2) is defined as a 0 ° position in the circumferential direction of the conductive roll 10, usually, an area of −45 ° to 45 ° and A region of 135 ° to 225 ° can be divided into a low resistance portion, a region of 45 ° to 135 ° and a region of 225 ° to 315 ° (−45 °) can be divided into a high resistance portion.

  The reason why the low resistance portion and the high resistance portion appear symmetrically due to the orientation of the bubble shape (bubble diameter) in the foamed elastic layer 14 is not clear, but one reason is that the foamed elastic layer It is conceivable that the density of the conductive agent contained in 14 depends on the shape of the bubbles 18. That is, as shown in FIG. 2, when each bubble 18 in the foamed elastic layer 14 has a substantially elliptical shape, the density of the conductive agent tends to increase near the both ends in the long axis direction, and the resistance tends to be low. The density of the agent becomes small and tends to be high resistance. If the conductive roll 10 having such a resistance difference due to the orientation of the bubbles 18 is continuously used as a transfer roll of the image forming apparatus, the resistance difference is further increased and the density of the image is likely to be uneven. It is considered to be.

However, the conductive roll 10 according to the present embodiment is bonded to the support 12 through the adhesive layers 16a and 16b having different conductivity in the high resistance portion and the low resistance portion of the foamed elastic layer 14, and thereby the bubbles The difference in conductivity of the foamed elastic layer 14 due to the 18 orientation is suppressed. For example, the adhesive layer 16a provided with at least ionic conductivity is used in the low resistance portion, and the adhesive layer 16b provided with at least electronic conductivity is used in the high resistance portion. The ion conductive adhesive 16a has a higher resistance increase rate during use than the electronic conductive adhesive 16b, that is, has a low electrical conductivity. Utilizing this property, by increasing the volume resistance increase rate of the low resistance portion of the foamed elastic layer 14 to be equal to or higher than the resistance increase rate of the high resistance portion, expansion of resistance in-plane unevenness during use is suppressed. .
Also, for example, when using an adhesive containing the same conductive agent as the adhesive layers 16a and 16b, the content of the conductive agent contained in the adhesive layer 16a is less than that contained in the adhesive layer 16b. The conductivity of the adhesive layer 16a is lower than that of the adhesive layer 16b. Utilizing this property, even if the volume resistance increase rate of the low resistance portion of the foamed elastic layer 14 is equal to or higher than the resistance increase rate of the high resistance portion, the expansion of the resistance in-plane unevenness during use is suppressed. .

  Examples of the ion conductive adhesive 16a include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium; perchlorates and chlorates of alkaline earth metals An adhesive containing fine powder such as;

  Examples of the electronic conductive adhesive 16b include carbon black such as furnace black, thermal black, channel black, ketjen black, acetylene black, and color black; pyrolytic carbon; graphite; aluminum, copper, nickel, stainless steel, and the like. Various metals or alloys; Various metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, tin oxide-indium oxide solid solution; Examples of the adhesive include.

  Then, as shown in FIG. 2, the foamed elastic layer 14 is divided into a high resistance portion and a low resistance portion at intervals of 90 °, and the ion conductive adhesive 16a and the electronic conductivity around the support 12 along the axial direction. By spreading the adhesive 16b separately, expansion of the resistance difference in the entire roll is effectively suppressed. Note that the method of separately applying the adhesive is not limited to that in FIG. 2, and the conductive support 12 and the foamed elastic layer 14 are suppressed from the difference in conductivity caused by the orientation of the bubbles 18 in the foamed elastic layer 14. Thus, what is necessary is just to adhere | attach through the at least 2 types of contact bonding layer from which electroconductivity differs.

  For example, as shown in FIG. 2, when one of the longitudinal directions of the bubbles of the foamed elastic layer 14 is defined as the 0 ° position in the circumferential direction of the conductive roll 10, the −20 ° to 20 ° and 160 ° to The resistance is particularly low at a position of 200 °, and the resistance tends to be particularly high at positions of 70 ° to 110 ° and 250 ° to 290 °. Therefore, as shown in FIG. 3, an adhesive layer 16a having a large resistance increase is provided around the cored bar (support) 12 at positions corresponding to at least −20 ° to 20 ° and 160 ° to 200 °. It is only necessary to provide the adhesive layer 16b having a small resistance increase at positions of 70 ° to 110 ° and 250 ° to 290 °. Since the resistance difference is relatively small in the area other than the above (the positions of 20 ° to 70 °, 110 ° to 160 °, and 200 ° to 250 °) 16c of the foamed elastic layer 14, any one of the above adhesives is used. Alternatively, another adhesive having conductivity between the two types of adhesives 16a and 16b may be used. As described above, if the adhesive layers 16a and 16b are reliably applied only to the portion where the resistance difference of the foamed elastic layer 14 is particularly large, the expansion of the resistance difference is suppressed and it is not necessary to perform the application with high accuracy. Therefore, productivity can be improved. If the periphery of the metal core 12 is finely divided using various types of adhesives, it becomes difficult to separate the coating, which may lead to a decrease in productivity. Therefore, it is preferable that the adhesive agent to be used is 2 types-4 types, More preferably, they are 2 types.

Although the method to manufacture the electroconductive roll 10 which concerns on this embodiment is not specifically limited, For example, it manufactures suitably by the following methods.
First, a foaming agent is added to polyurethane to produce a plate-like urethane foam. At this time, the urethane foam expands in the vertical direction while foaming, and the bubbles 18 also extend in the vertical direction, resulting in cell-shaped (cell diameter) orientation. From this urethane foam, for example, a cylindrical foamed elastic body is cut out in a desired size to form a center hole, and immersed in a conductive treatment solution containing water, a crosslinkable resin, a conductive agent, and the like. Thereby, the conductive treatment liquid is impregnated in the bubbles 18 of the urethane foam. Subsequently, after passing this between rolls and removing a water | moisture content etc., it is heat-dried. As a result, a polymer containing a conductive substance is formed on the wall surface (cell skeleton surface) of the bubble 18 contained in the foamed elastic layer 14, and the foamed elasticity having conductivity in which the shape of the bubble 18 is oriented as shown in FIG. A body 14 is obtained.

  On the other hand, around the cored bar (support) 12, when the cored bar 12 is inserted into the center hole 13 of the foamed elastic body 14, there is a difference in conductivity of the foamed elastic layer 14 due to the orientation of the bubbles 18. Two types of adhesives 16a and 16b are applied separately so as to be suppressed. The method of providing the adhesives 16a and 16b around the cored bar 12 is not particularly limited as long as the predetermined adhesive can be separately applied to the predetermined region. For example, a method such as spray coating, flow coating method, Dip coating method, or the like can be used. Adopted.

  Note that the conductivity (resistance value) around the foamed elastic body 14 may be divided into a high resistance portion and a low resistance portion by actual measurement, but the high resistance portion is based on the orientation of the bubbles 18 as shown in FIG. And divided into low resistance parts. Then, the cored bar 12 is inserted into the center hole of the foamed elastic body 14 so that the difference in conductivity of the foamed elastic layer 14 is reduced by the two types of adhesives 16 a and 16 b separately applied around the cored bar 12. After bonding, the outer circumference is polished by a cylindrical polishing method, a centerless polishing method, or the like to be processed into a roll shape. Thereby, the electroconductive roll 10 which concerns on this embodiment as shown in FIG.1 and FIG.2 is obtained. In addition, after shape | molding the surface of the foaming elastic body cut out from urethane foam in roll shape by grinding | polishing etc., you may insert and adhere the metal core 12 which applied the adhesive agents 16a and 16b separately.

<Image forming apparatus and process cartridge>
Although the use of the conductive roll 10 according to the present embodiment is not particularly limited, for example, it is suitably used as a transfer roll in an image forming apparatus or a process cartridge thereof. 5 to 8 are schematic views illustrating the configuration of a process cartridge or an image forming apparatus including the conductive roll 10 according to the present embodiment, respectively.

  An image forming apparatus 100 shown in FIG. 5 mainly includes a process cartridge 20, an electrostatic latent image forming apparatus (exposure apparatus) 30, a transfer roll 40, an intermediate transfer body 50, and an apparatus main body (not shown). It has. The process cartridge 20 is a case in which the electrophotographic photosensitive member 1, the charging roll 21, the developing device 25, the cleaning device 27, and the fibrous member (flat brush shape) 29 are combined and integrated in a case with mounting rails. is there. The process cartridge 20 is detachable from the apparatus main body and constitutes an image forming apparatus together with the apparatus main body.

An opening for exposure is provided in the case of the process cartridge 20, and the exposure device 30 is disposed at a position where the electrophotographic photosensitive member 1 can be exposed from the opening of the process cartridge 20.
The transfer roll 40 is disposed at a position facing the electrophotographic photosensitive member 1 with the intermediate transfer member 50 interposed therebetween, and a part of the intermediate transfer member 50 is disposed so as to be in contact with the electrophotographic photosensitive member 1. Note that the transfer roll 40 and the intermediate transfer member 50 may be included in the process cartridge 20.

  In the image forming apparatus or process cartridge having such a configuration, if the conductive roll 10 according to the present embodiment is provided as the transfer roll 40, the conductive roll 10 is made of adhesives 16a and 16b of different types (conductive). The difference in resistance around the roll is suppressed to a small level by coating, and the increase in the difference in resistance during use is suppressed, and the occurrence of uneven density in the image is effectively suppressed.

<Toner>
The toner used in the image forming apparatus using the conductive roll according to the present embodiment is not particularly limited, and any known toner can be used.
For example, the toner has an average shape factor (ML ² / A × π / 4 × 100, where ML represents the maximum length of the toner particles, A represents the projected area of the toner particles, and π represents the circumference) Is preferably 100 or more and 150 or less, and more preferably 100 or more and 140 or less. Further, the toner preferably has a volume average particle size of 2 μm or more and 12 μm or less, more preferably 3 μm or more and 12 μm or less, and further preferably 3 μm or more and 9 μm or less. By using a toner satisfying such an average shape factor and volume average particle diameter, a high-quality image can be obtained with high developability and transferability.

  Further, the method for producing the toner is not limited. For example, a kneading and pulverizing method in which a binder resin, a colorant and a release agent, and a charge control agent as necessary are added, kneaded, pulverized, and classified; A method of changing the shape of particles obtained by a pulverization method by mechanical impact force or thermal energy; emulsion polymerization of a polymerizable monomer of a binder resin, a formed dispersion, a colorant and a release agent An emulsion, an agglomeration method for obtaining toner particles by mixing, if necessary, a dispersion of a charge control agent or the like and aggregating and heat-fusing; a polymerizable monomer for obtaining a binder resin; and a colorant A suspension polymerization method in which a solution of a release agent and, if necessary, a charge control agent is suspended in an aqueous solvent for polymerization; a binder resin, a colorant and a release agent, and a charge control agent as required Toner produced by a suspension method, etc., in which the solution is suspended in an aqueous solvent and granulated is used. .

  In addition, a known method such as a production method in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to have a core-shell structure may be used. The toner production method is preferably a suspension polymerization method, an emulsion polymerization aggregation method, or a dissolution suspension method in which an aqueous solvent is used from the viewpoint of shape control and particle size distribution control, and an emulsion polymerization aggregation method is particularly desirable.

  The toner base particles are composed of a binder resin, a colorant, and a release agent, and include silica and a charge control agent as necessary.

  Binder resins used for toner base particles include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc. Α-methylene aliphatics such as vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers and copolymers of monocarboxylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone Polyester resins by copolymerization of dicarboxylic acids and diols.

  Particularly representative binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. A polymer, polyethylene, a polypropylene, a polyester resin etc. are mentioned. Further, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned.

  Coloring agents include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and lamp black. Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 is exemplified as a representative example.

  Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer tropical wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  Known charge control agents are used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When toner is produced by a wet process, it is desirable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  The toner used in the developing device 25 is manufactured by mixing the toner base particles and the external additive with a Henschel mixer or a V blender. Further, when the toner base particles are produced by a wet method, they may be externally added by a wet method.

  Lubricating particles may be added to the toner used in the developing device 25. Lubricating particles include solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids and fatty acid metal salts, low molecular weight polyolefins such as polypropylene, polyethylene and polybutene, silicones having a softening point upon heating, oleic amides , Aliphatic amides such as erucic acid amide, ricinoleic acid amide, stearic acid amide, etc., plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, animal waxes such as beeswax, Minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax, and petroleum-based waxes, and modified products thereof are used. These are used individually by 1 type or in combination of 2 or more types. However, the volume average particle diameter is preferably in the range of 0.1 μm or more and 10 μm or less, and those having the above chemical structure may be pulverized to make the particle diameters uniform. The amount added to the toner is desirably in the range of 0.05% by mass to 2.0% by mass, and more desirably in the range of 0.1% by mass to 1.5% by mass.

  To the toner used in the developing device 25, inorganic particles, organic particles, composite particles obtained by attaching inorganic particles to the organic particles, or the like may be added for the purpose of removing the adhered matter or deteriorated matter on the surface of the electrophotographic photosensitive member. .

  Inorganic particles include silica, alumina, titania, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, Various inorganic oxides such as manganese oxide, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, and boron nitride, nitrides, borides, and the like are preferably used.

  In addition, the inorganic particles may be mixed with titanium coupling agents such as tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, γ- (2- Aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxy Silane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane The treatment may be performed with a silane coupling agent such as run, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, and p-methylphenyltrimethoxysilane. In addition, those hydrophobized with higher fatty acid metal salts such as silicone oil, aluminum stearate, zinc stearate, calcium stearate and the like are also desirably used.

  Examples of the organic particles include styrene resin particles, styrene acrylic resin particles, polyester resin particles, and urethane resin particles.

  The particle diameter is preferably 5 nm to 1000 nm, more preferably 5 nm to 800 nm, and still more preferably 5 nm to 700 nm in terms of volume average average particle diameter. If the volume average particle diameter is less than the lower limit, the polishing ability tends to be lacking. On the other hand, if the volume average particle diameter exceeds the upper limit, the surface of the electrophotographic photosensitive member tends to be damaged. Moreover, it is desirable that the sum of the addition amounts of the above-described particles and the lubricating particles is 0.6% by mass or more.

  Other inorganic oxides added to the toner are small-diameter inorganic oxides with a primary particle size of 40 nm or less for powder flowability, charge control, etc. It is desirable to add a larger diameter inorganic oxide. These inorganic oxide particles may be known ones, but it is desirable to use silica and titanium oxide in combination for precise charge control. Further, the surface treatment of the small-diameter inorganic particles increases the dispersibility and increases the effect of increasing the powder fluidity. Furthermore, it is desirable to add carbonates such as calcium carbonate and magnesium carbonate and inorganic minerals such as hydrotalcite in order to remove discharge products.

  In addition, the color toner for electrophotography is used by mixing with a carrier. As the carrier, iron powder, glass beads, ferrite powder, nickel powder, or those having a resin coating on the surface thereof are used. The mixing ratio with the carrier is arbitrarily set.

<Cleaning device>
The cleaning device 27 includes a fibrous member (roll shape) 27a and a cleaning blade (blade member) 27b.
The cleaning device 27 is provided with the fibrous member 27a and the cleaning blade 27b, but may be provided with either one. The fibrous member 27a may have a toothbrush shape (flat brush shape) in addition to a roll shape. Further, the fibrous member 27a may be fixed to the cleaning device main body, may be supported so as to be rotatable, and may be supported so as to be capable of oscillating in the photosensitive member axial direction. As the fibrous member 27a, polyester, nylon, acrylic, etc., cloth-like ones made of ultrafine fibers such as Toraysee (made by Toray Industries), resin fibers such as nylon, acrylic, polyolefin, polyester, etc. are used as a substrate or carpet. The brush-like thing etc. which were flocked to are mentioned. Further, as the fibrous member 27a, a conductive powder or an ionic conductive agent is added to the above-described material to impart conductivity, or a conductive layer is formed inside or outside of each fiber. May be used. When conductivity is imparted, the resistance value of the single fiber is preferably 10 ² Ω or more and 10 ⁹ Ω or less. The fiber thickness of the fibrous member 27a is desirably 30 d (denier) or less, more desirably 20 d or less, and the fiber density is desirably 20,000 fibers / inch ² or more, more desirably 30,000 fibers / inch. inch ² or more.

  The cleaning device 27 is required to remove deposits (for example, discharge products) on the surface of the photoreceptor. In order to achieve this purpose over a long period of time and stabilize the function of the cleaning member, the cleaning member may be supplied with a lubricating substance (lubricating component) such as metal soap, higher alcohol, wax, silicone oil or the like. desirable.

  For example, when a roll-shaped member is used as the fibrous member 27a, it is desirable to supply a lubricating component to the surface of the electrophotographic photoreceptor by bringing it into contact with a lubricating substance such as metal soap or wax. A normal rubber blade is used as the cleaning blade 27b. As described above, when a rubber blade is used as the cleaning blade 27b, supplying a lubricating component to the surface of the electrophotographic photosensitive member is particularly effective in suppressing chipping and wear of the blade.

<Exposure device>
The exposure device 30 may be any device that exposes the charged electrophotographic photosensitive member 1 to form an electrostatic latent image. Further, it is desirable to use a multi-beam surface emitting laser as the light source of the exposure apparatus 30.

<Intermediate transfer member>
As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber or the like having semiconductivity is used. Further, as the form of the intermediate transfer member 50, a drum-like one is used in addition to the belt shape. Note that a direct transfer type image forming apparatus that does not include the intermediate transfer member may be used.

  The transfer medium is not particularly limited as long as it is a medium that transfers a toner image formed on the electrophotographic photosensitive member 1. For example, when transferring directly from the electrophotographic photosensitive member 1 to paper or the like, paper or the like is a transfer medium, and when the intermediate transfer member 50 is used, the intermediate transfer member is a transfer medium.

  FIG. 6 is a schematic configuration diagram illustrating an image forming apparatus according to another embodiment. In the image forming apparatus 110 shown in FIG. 6, the electrophotographic photosensitive member 1 is fixed to the apparatus main body, and the charging device 22, the developing device 25, and the cleaning device 27 are each formed as a cartridge. As independent. Note that the charging device 22 includes a charging device for charging by a corona discharge method.

  In this image forming apparatus 110, the electrophotographic photosensitive member 1 and each other apparatus are separated, and the charging device 22, the developing device 25, and the cleaning device 27 are screwed, caulked, adhered, or welded to the image forming apparatus main body. Without being fixed, it can be removed by pulling and pushing. Also in the image forming apparatus 110 having such a configuration, as the transfer roll 40, the conductive layer in which the adhesive layer between the cored bar and the foamed elastic layer is separately coated so that the difference in conductivity in the foamed elastic layer becomes small. By providing the roll, expansion of the resistance difference is suppressed, and the occurrence of density unevenness in the image is effectively suppressed.

The image forming apparatus 120 shown in FIG. 7 is a tandem-type full-color image forming apparatus equipped with four process cartridges 20. The image forming apparatus 120 has the same configuration as that of the image forming apparatus 100 except that it is a tandem system, and four process cartridges 20 are arranged in parallel on the intermediate transfer member 50, and each image has one color. Two electrophotographic photosensitive members are used.
Even in such a tandem image forming apparatus 120, the adhesives 16a and 16b between the cored bar and the foamed elastic layer 14 so as to suppress the difference in conductivity caused by the orientation of the bubbles 18 in the foamed elastic layer 14 are also used. By providing the transfer rolls separately applied, the occurrence of density unevenness in the image is effectively suppressed.

  The image forming apparatus 130 shown in FIG. 8 is a so-called four-cycle image forming apparatus that forms toner images of a plurality of colors with one electrophotographic photosensitive member. The image forming apparatus 130 includes a photosensitive drum 1 that is rotated by a driving device (not shown) at a predetermined rotational speed in the direction of an arrow A in the drawing, and a photosensitive drum 1 is disposed above the photosensitive drum 1. A charging device 22 for charging the outer peripheral surface of the body drum 1 is provided.

  An exposure device 30 including a surface emitting laser array as an exposure light source is disposed above the charging device 22. The exposure device 30 modulates a plurality of laser beams emitted from a light source in accordance with an image to be formed and deflects the laser beams in the main scanning direction so that the axis of the photosensitive drum 1 is on the outer peripheral surface of the photosensitive drum 1. Scan in parallel. Thereby, an electrostatic latent image is formed on the outer peripheral surface of the charged photosensitive drum 1.

  A developing device 25 is disposed on the side of the photosensitive drum 1. The developing device 25 includes a roller-shaped container that is rotatably arranged. Four containers are formed inside the container, and developing units 25Y, 25M, 25C, and 25K are provided in each container. Each of the developing devices 25Y, 25M, 25C, and 25K includes a developing roller 26, and stores therein toners of yellow (Y), magenta (M), cyan (C), and black (K), respectively.

  The full-color image is formed by the image forming apparatus 130 when the photosensitive drum 1 forms an image for four colors. That is, while the photosensitive drum 1 forms an image four times, the charging device 22 charges the outer peripheral surface of the photosensitive drum 1, and the exposure device 30 displays Y, M, C, and K image data representing a color image to be formed. Scanning the outer peripheral surface of the photosensitive drum 1 with a laser beam modulated according to any one of the above, while switching image data used for modulation of the laser beam every time the photosensitive drum 1 forms an image. repeat. Further, the developing device 25 operates the developing device corresponding to the outer peripheral surface in a state where any of the developing rollers 26 of the developing devices 25Y, 25M, 25C, and 25K corresponds to the outer peripheral surface of the photosensitive drum 1. The photosensitive drum 1 is the one that develops the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1 to a specific color and forms a toner image of the specific color on the outer peripheral surface of the photosensitive drum 1. Each time image formation is performed, the image forming unit is repeated while rotating the container so that the developing unit used for developing the electrostatic latent image is switched. As a result, Y, M, C, and K toner images are sequentially formed on the outer peripheral surface of the photosensitive drum 1.

  An endless intermediate transfer belt 50 is disposed below the photosensitive drum 1. The intermediate transfer belt 50 is wound around rollers 51, 53, and 55, and is disposed so that the outer peripheral surface is in contact with the outer peripheral surface of the photosensitive drum 1. The rollers 51, 53, and 55 are rotated by transmission of a driving force of a motor (not shown) to rotate the intermediate transfer belt 50 in the direction of arrow B in the figure.

  A primary transfer roll 40 is disposed on the opposite side of the photosensitive drum 1 across the intermediate transfer belt 50, and Y, M, C, and K toner images sequentially formed on the outer peripheral surface of the photosensitive drum 1. Are transferred one by one to the image forming surface of the intermediate transfer belt 50 by the transfer roll 40, and finally, all the Y, M, C, and K toner images are laminated on the intermediate transfer belt 50.

  Further, a lubricant supply device 29 and a cleaning device 27 that are in contact with the outer peripheral surface of the photosensitive drum 1 are disposed on the opposite side of the developing device 25 across the photosensitive drum 1. When the toner image formed on the outer peripheral surface of the photosensitive drum 1 is transferred to the intermediate transfer belt 50, the lubricant is supplied to the outer peripheral surface of the photosensitive drum 1 by the lubricant supply device 29, and the The area that has held the transferred toner image is cleaned by the cleaning device 27.

  A paper feeding device 60 is disposed below the intermediate transfer belt 50, and a plurality of sheets P as recording materials are accommodated in the paper feeding device 60 in a stacked state. A take-out roller 61 is arranged obliquely above and to the left of the paper feeding device 60. A roller pair 63 and a roller 65 are arranged in this order on the downstream side in the take-out direction of the paper P by the take-out roller 61. The uppermost recording paper in the stacked state is taken out from the paper feeding device 60 by rotating the take-out roller 61 and is conveyed by the roller pair 63 and the roller 65.

  A secondary transfer roll 42 is disposed on the opposite side of the so-called backup roller 55 with the intermediate transfer belt 50 interposed therebetween. The sheet P conveyed by the roller pair 63 and the roller 65 is sent between the intermediate transfer belt 50 and the secondary transfer roll 42, and the toner image formed on the image forming surface of the intermediate transfer belt 50 is transferred to the backup roll 55. The image is transferred onto the paper P by the transfer roll 42. A fixing device 44 having a pair of fixing rollers is disposed downstream of the transfer roll 42 in the conveyance direction of the paper P. The paper P on which the toner image is transferred is transferred by the fixing device 44 to the transferred toner image. After being fused and fixed, the sheet is discharged out of the image forming apparatus 130 and placed on a sheet receiving tray (not shown).

  Even in such a four-cycle image forming apparatus 130, at least one of the primary transfer roll 40 and the secondary transfer roll 42, and preferably both, bubbles in the foamed elastic layer 14 as shown in FIGS. 18 is provided with a transfer roll in which the adhesives 16a and 16b between the cored bar 12 and the foamed elastic layer 14 are separately coated so as to suppress the difference in conductivity caused by the orientation of 18; Generation is effectively suppressed.

  In the above embodiment, the case where different types of adhesives are separately applied according to the orientation of the bubbles in the foamed elastic layer or the resistance difference resulting therefrom has been described, but the same type of adhesive is applied over the entire circumference of the core metal. Used, by changing the thickness of the adhesive layer according to the orientation of the foam in the foamed elastic layer or the resistance difference, that is, by making the film thickness of the adhesive in the low resistance part larger than the film thickness of the adhesive in the high resistance part The uneven resistance of the entire roll may be alleviated.

  Hereinafter, although an example and a comparative example are explained, the present invention is not limited to the following examples.

Example 1
<Formation of adhesive layer>
Hot melt adhesive A (main agent: polyamide) containing carbon black (SPECIAL BLACK 4 (manufactured by Degussa)) as an electronic conductive agent, and hot melt adhesive B (main agent: polyamide) containing lithium perchlorate as an ionic conductive agent Each conductive agent was dispersed in a solution in which the main component of the hot melt adhesive was dissolved in a solvent (toluene / methanol 1: 1 mixed solvent).
As shown in FIGS. 2 and 4, hot melt adhesives A and B are alternately applied every 90 ° along the axial direction on the surface of a cored bar (diameter: 7 mm, length: 310 mm, material: SUM24L). did. After the application, the adhesive was dried in a drying furnace to form a hot melt adhesive layer on the cored bar.

<Preparation of conductive urethane foam (foamed elastic layer)>
A rectangular parallelepiped having a length of 300 to 400 mm, a width of 350 to 500 mm, and a height of 25 mm was cut out from a soft slab foam (trade name “EP70” manufactured by Inoac Corporation). This foam is a conductive treatment liquid in which carbon black is contained in an amount of 36% by mass and an aqueous dispersion and an acrylic emulsion (trade name “Nipol LX852” manufactured by Nippon Zeon Co., Ltd.) are mixed in a 1: 1 ratio. For 10 minutes at 20 ° C.

  Thereafter, the foam in which bubbles were impregnated with water, carbon black and acrylic resin was passed between a pair of rolls set at a distance of 0.2 mm to remove moisture and the like. Next, this foam was heated and dried in a curing oven set at 100 ° C. for 60 minutes to remove moisture almost completely and to crosslink the acrylic resin. Carbon black was fixed to the foam wall and skeleton of the foam by an acrylic resin cured by crosslinking. Thereafter, the crosslinking of the acrylic resin progressed, and the carbon black was firmly fixed by the cell walls.

<Preparation of conductive roll>
A rectangular cylinder having a cross section of 20 mm square and a length of 300 mm is cut out from a rectangular parallelepiped foam subjected to the above-described treatment, and a diameter of 6 mm for inserting a cored bar over the entire length in the axial direction at the center of the cross section. A through hole was provided. Thereafter, the cored bar having an adhesive layer formed on the surface was inserted into the through-hole and bonded together by aligning the foam orientation of the foam and the position of the adhesive layer. Then, the surface was polished by a conventional method to obtain a conductive roll having an outer diameter of 12 mm.

<Evaluation of conductive roll>
The above-described conductive roll was used as a primary transfer roll of a four-cycle type image forming apparatus (product name: Docu Print C3050), and durability against occurrence of density unevenness of the image was evaluated. Moreover, the resistance in-plane nonuniformity of the conductive roll before and after actual machine evaluation was evaluated using Advantest R8320.

Comparative Examples 1-3
A conductive roll was produced in the same manner as in Example 1 except that the core metal and conductive urethane foam having the same material and shape as those used in Example 1 were used and the adhesive layer was changed. As an adhesive, an insulating adhesive (Comparative Example 1), an adhesive A (Comparative Example 2), or an adhesive B (Comparative Example 3) made of only polyamide without containing a conductive agent is used, and each adhesive is cored. An adhesive layer was formed by coating on the entire surface around the gold.

The conductive rolls obtained in Comparative Examples 1 to 3 are used separately as primary transfer rolls of a 4-cycle image forming apparatus (product name: Docu Print C3050), respectively, and have durability against occurrence of density unevenness in images. evaluated. Moreover, the resistance in-plane nonuniformity of the conductive roll before and after actual machine evaluation was evaluated using Advantest R8320.
Table 1 shows the evaluation results when the conductive rolls of Example 1 and Comparative Examples 1 to 3 were used.

  From the results shown in Table 1, even when printing is continued using the conductive roll according to the present embodiment as a primary transfer roll, the resistance in-plane unevenness (resistance difference) of the roll can be suppressed to be small and image density unevenness occurs. It turns out that it is difficult.

Example 2
A conductive roll was produced and evaluated in the same manner as in Example 1 except that the formation of the adhesive was changed as follows.
<Formation of adhesive layer>
Hot melt adhesive C containing 20 parts by mass of carbon black (SPECIAL BLACK 4, manufactured by Degussa) as a conductive agent and hot melt adhesive C containing 10 parts by mass of carbon black (SPECIAL BLACK 4, manufactured by Degussa) Agent D (main agent: polyamide) was prepared. In addition, each electrically conductive agent was disperse | distributed to the solution in which the main ingredient of the hot-melt-adhesive was dissolved in the solvent (toluene).
As shown in FIGS. 2 and 4, hot melt adhesives C and D are alternately applied to the surface of the core metal (diameter: 7 mm, length: 310 mm, material: SUM24L) along the axial direction every 90 °. did. After the application, the adhesive was dried in a drying furnace to form a hot melt adhesive layer on the cored bar.

<Evaluation of conductive roll>
The above-mentioned conductive roll was used as a primary transfer roll of a 4-cycle type image forming apparatus (product name: Docu Print C3050), and durability against occurrence of density unevenness of the image was evaluated. Moreover, the resistance in-plane nonuniformity of the conductive roll before and after actual machine evaluation was evaluated using Advantest R8320.

Examples 3-5
As shown in Table 2, a conductive roll was prepared and evaluated in the same manner as in Example 2 except that a urethane foam having a resistance unevenness larger than that in Example 2 was used.

Example 6
<Formation of adhesive layer>
A hot melt adhesive (main agent: polyamide) containing 15 parts by mass of carbon black (SPECIAL BLACK 4, manufactured by Degussa) was prepared as a conductive agent. The conductive agent was dispersed in a solution in which the main component of the hot melt adhesive was dissolved in a solvent (toluene).
As shown in FIG. 2 and FIG. 4, the thickness after drying the hot melt adhesive every 90 ° along the axial direction on the surface of the core metal (diameter: 7 mm, length: 310 mm, material: SUM24L) It apply | coated alternately so that it might become 50 micrometers and 70 micrometers. After the application, the adhesive was dried in a drying furnace to form a hot melt adhesive layer on the cored bar.

<Preparation of conductive urethane foam (foamed elastic layer)>
A conductive urethane foam was produced in the same manner as in Example 1.

<Preparation of conductive roll>
A rectangular column having a cross section of 20 mm square and a length of 300 mm was cut out from the obtained rectangular parallelepiped foam, and a through hole having a diameter of 6 mm was provided in the central portion of the cross section so as to pass through the metal core over the entire length in the axial direction. . Thereafter, the core metal having an adhesive layer formed on the surface was inserted into the through hole and adhered. Then, the surface was polished by a conventional method to obtain a conductive roll having an outer diameter of 12 mm.

<Evaluation of conductive roll>
The above-mentioned conductive roll was used as a primary transfer roll of a 4-cycle type image forming apparatus (product name: Docu Print C3050), and durability against occurrence of density unevenness of the image was evaluated. Moreover, the resistance in-plane nonuniformity of the conductive roll before and after actual machine evaluation was evaluated using Advantest R8320. As a result, the resistance unevenness before the evaluation test was Δ = 0.20 logΩ, and the resistance unevenness after the evaluation test was Δ = 0.28 logΩ.

Examples 7-20
Conducting in the same manner as in Example 6 using a metal core and conductive urethane foam having the same material and shape as those used in Example 6 and having a larger resistance variation of the urethane foam than that used in Example 6. Sex rolls were made and evaluated.
As a result, the fluctuation range of the resistance unevenness before and after the actual machine evaluation test was larger than that in Example 6.

Comparative Examples 4 and 5
A conductive roll was produced in the same manner as in Example 6 except that a cored bar and conductive urethane foam having the same material and shape as those used in Example 6 were used and the adhesive layer was changed. As the adhesive, the same type of adhesive (Comparative Example 4) or insulating adhesive (Comparative Example 5) as used in Example 6 is used, and the thickness is uniform over the entire surface around the cored bar. Thus, an adhesive layer was formed.

The conductive rolls obtained in Comparative Examples 4 and 5 above are used separately as primary transfer rolls in a 4-cycle image forming apparatus (product name: Docu Print C3050), respectively, and have durability against occurrence of density unevenness in the image. evaluated. Moreover, the resistance in-plane nonuniformity of the conductive roll before and after actual machine evaluation was evaluated using Advantest R8320.
Table 3 shows the evaluation results when the conductive rolls of Examples 6 to 20 and Comparative Examples 4 and 5 were used.

  As mentioned above, although this invention was demonstrated, this invention is not limited to the said embodiment and Example. For example, the use of the conductive roll according to the present invention is not limited to the transfer roll of the image forming apparatus, and can be used for a backup roll, a charging roll, and the like. Moreover, you may form coating layers, such as rubber material, around a foaming elastic layer as needed.

It is the schematic which shows the electroconductive roll which concerns on this embodiment. It is the schematic which shows the AA line cross section in FIG. It is a schematic sectional drawing which shows the area | region which provides the adhesive agent from which electroconductivity differs around the electroconductive support body which concerns on this embodiment. It is the schematic explaining an example of the manufacturing method of the electroconductive roll which concerns on this embodiment. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the other example of the image forming apparatus which concerns on this embodiment. It is a schematic block diagram which shows the other example of the image forming apparatus which concerns on this embodiment. It is a schematic block diagram which shows the other example of the image forming apparatus which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electrophotographic photosensitive member, 10 ... Conductive roll, 12 ... Conductive support body (core metal), 14 ... Foam elastic layer (foam elastic body), 16a ... 1st adhesive layer, 16b ... 2nd adhesive layer , 18 ... bubbles, 20 ... process cartridge, 21 ... charging roll, 22 ... charging device, 25 ... developing device, 40 ... transfer roll, 42 ... transfer roll, 44 ... fixing device, 50 ... intermediate transfer member, 55 ... backup roll 60, sheet feeding device, 100, 110, 120, 130, image forming apparatus.

Claims (8)

A conductive roll comprising a conductive support, and a foamed elastic layer having conductivity that is bonded to the entire periphery of the conductive support through an adhesive layer having conductivity,
The shape of the bubbles in the foamed elastic layer has orientation in one direction perpendicular to the axial direction of the conductive support,
The adhesive layer includes at least two types of adhesive layers having different electrical conductivity. When viewed from the axial direction of the conductive roll, one of the longitudinal directions of the bubbles of the foamed elastic layer is 0 in the circumferential direction of the conductive roll. When defined as a position, the first adhesive layer is provided at a position of at least −20 ° to 20 ° and 160 ° to 200 ° as the adhesive layer, and at least 70 ° to 110 ° and 250 ° to A second adhesive layer is provided at a position of 290 °;
Said first adhesive layer, said second adhesive layer lower conductivity than,
The conductivity of the region other than the first adhesive layer and the second adhesive layer in the adhesive layer is the same as or between those of the first adhesive layer and the second adhesive layer. A conductive roll characterized by   The conductive roll according to claim 1, wherein the first adhesive layer has ionic conductivity, and the second adhesive layer has electronic conductivity.   The first adhesive layer and the second adhesive layer contain the same conductive agent, and the content of the conductive agent in the first adhesive layer is greater than the content of the conductive agent in the second adhesive layer. The conductive roll according to claim 1, wherein the conductive roll is small.   The conductive roll according to claim 1, wherein a thickness of the first adhesive layer is larger than a thickness of the second adhesive layer.   The conductive foam according to any one of claims 1 to 4, wherein the foamed elastic layer is a urethane foam.   6. The conductivity of the foamed elastic layer is imparted by forming a polymer containing a conductive material on a wall surface of a cell of the foamed elastic layer. The electroconductive roll of Claim 1.   A process cartridge comprising the conductive roll according to claim 1.   An image forming apparatus comprising the conductive roll according to claim 1.

Images