JP2019095656A - Developing roller, method for manufacturing developing roller, developing device, and image forming device - Google Patents

Abstract

To provide a developing roller excellent in environmental resistance and durable printing performance while sufficiently preventing occurrence of filming.SOLUTION: A developing roller 1 comprises a shaft body 2, an elastic layer 3 provided on the outer peripheral surface of the shaft body 2 and a coating layer 4 provided on the outer side of the elastic layer 3. The developing roller has spiral grooves with a lead angle in an axial direction on the outer peripheral surface of the elastic layer 3, where an axial interval of the spiral grooves is 0.01 mm or more and 0.3 mm or less and depth of the spiral grooves is 5 μm or more and 40 μm or less. The coating layer 4 includes a filler. A particle diameter of the filler included in the coating layer is 1 μm or more and 5 μm or less and thickness of the coating layer is 10 nm or more and 5000 nm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a developing roller in which the occurrence of filming is favorably suppressed and which is excellent in environmental resistance and durable printing performance, a method of manufacturing the developing roller, a developing device including the developing roller, and an image forming apparatus.

  A developing roller used in an image forming apparatus such as a copying machine, a printer, or a facsimile adopting an electrophotographic method has a function of conveying a developer to an image bearing member on which an electrostatic latent image is formed. The developer transportability of the developing roller affects the quality of the image forming apparatus, particularly the printing density. Accordingly, it has been considered to improve the developer transportability of the developing roller by forming irregularities on the surface of the developing roller and adjusting the electrical characteristics of various materials constituting the developing roller.

  Here, when the developing roller is used for a long time, the developer may be fixed on the surface thereof (referred to as "filming"). In such filming, for example, when the developer is charged or adhered, the developer is deformed or destroyed by the sliding stress of a blade or the like that is in pressure contact with the developing roller, and the development by the frictional heat with the blade or the like It is considered to be produced due to melting of the agent and the like. Heretofore, in the production of a developing roller, it has been required to provide a developing roller in which the occurrence of filming is suppressed as much as possible, and thereby the durable printing performance is stabilized.

  As a developing roller examined from such a point of view, for example, in Patent Document 1, an elastic layer is formed on the outer peripheral surface of a shaft using a molding die, and the outer peripheral surface of the elastic layer is used as the above-mentioned molding gold It is a manufacturing method of the developing roll formed on the transfer surface of the mold surface of the mold, and prior to the formation of the elastic layer, electroless composite plating is performed on the mold surface of the molding die, and the surface of the electroless composite plating layer The surface of the electroless composite plating layer is roughened by forming pits on the surface, and when the elastic layer is formed, the mold surface is transferred to the outer peripheral surface of the elastic layer to produce A roller is disclosed.

  Further, Patent Document 2 is a developing roll for an electrophotographic apparatus including a shaft, a rubber elastic layer molded on the outer periphery of the shaft, and a covering layer formed on the outer periphery of the rubber elastic layer. There is disclosed a developing roller for an electrophotographic apparatus characterized in that a large number of convex portions formed by mold transfer exist on the surface of the rubber elastic layer, and a predetermined equation is satisfied.

Further, Patent Document 3 has at least one elastic layer on an axial core and at least one surface layer on the outer periphery thereof, carries a developer and carries it, contacts the photosensitive drum, and generates an electrostatic latent image. In the developing roller for visualizing, the surface layer is made of a thermoplastic resin, the thickness is 5.0 nm or more and less than 2.0 μm, and the micro rubber hardness Hd of the elastic layer surface is 21 or more and 50 or less, The difference (Hs-Hd) between the micro rubber hardness Hd of the elastic layer surface and the micro rubber hardness Hs of the developing roller surface is 0 or more and 5 or less, and the surface roughness Ra ₁ of the elastic layer surface and the surface roughness of the developing roller A developing roller is disclosed which is characterized in that the difference of height Ra ₂ (Ra ₁ -Ra ₂ ) is between -0.20 μm and 0.20 μm.

JP, 2006-184608, A JP, 2011-175005, A JP, 2007-316524, A

  Here, in the image forming apparatus in recent years, an image forming apparatus having a long life is required for the purpose of reducing the load on the environment such as energy saving, and the developing roller used in the image forming apparatus as a part thereof is also required. There is a need for a developing roller in which the occurrence of filming is suppressed and the durable printing performance is stabilized. However, with the developing rollers described in Patent Document 1 to Patent Document 3, the occurrence of filming can not be suppressed to the extent that the performance of the image forming apparatus required in recent years can be sufficiently coped with, and the printing performance is not satisfactory. The

  In addition, when the developing roller is used for a long time under a high temperature and high humidity environment, the adhesion of the surface of the developing roller is increased, and thus the developer in contact with the surface of the developing roller may be fixed to the surface of the developing roller . As a result, the developer conveying force of the developing roller is lowered, which may result in a decrease in print density and image non-uniformity, and depending on the environment where the image forming apparatus is used, the durable printing performance may be further degraded. was there.

  Although there is also a method of examining the size and the material of the filler contained in the coating layer for these problems, it has not been possible to obtain a developing roller that can sufficiently cope with the above problems. Therefore, the present invention has been made in view of the above points, and an object of the present invention is to provide a developing roller in which the occurrence of filming is well suppressed and which is excellent in environmental resistance and durable printing performance.

  The inventors of the present invention conducted intensive studies in view of the above problems. As a result, it is found that the above-mentioned problems can be solved by forming a predetermined groove in the elastic layer and further forming the particle diameter of the filler contained in the coating layer and the thickness of the coating layer, thereby completing the present invention. It came to Specifically, the present invention provides the following.

  (1) A first aspect of the present invention is a developing roller comprising a shaft, an elastic layer provided on the outer peripheral surface of the shaft, and a covering layer provided outside the elastic layer, The elastic layer has a helical groove having a lead angle in the axial direction on the outer peripheral surface of the elastic layer, the axial interval of the helical groove is 0.01 mm or more and 0.3 mm or less, and the depth of the helical groove is Development is carried out, wherein the coating layer contains a filler, the particle size of the filler contained in the coating layer is 1 μm to 5 μm, and the thickness of the coating layer is 10 nm to 5000 nm. It is a roller.

  (2) A second aspect of the present invention is the developing roller according to (1), wherein the MD-1 hardness of the surface of the developing roller is 20 or more and 60 or less.

  (3) A third aspect of the present invention is the developing roller according to (1) or (2), wherein 50% from the axial center point of the elastic layer with respect to the entire axial length of the elastic layer It is characterized in that the winding direction of the spiral groove is reversed at the position below.

  (4) A fourth aspect of the present invention is a method of manufacturing the developing roller according to any one of (1) to (3), which comprises forming an elastic layer on the outer peripheral surface of the shaft. And the second step of forming the covering layer provided on the outside of the elastic layer, and in the first step, injection molding is performed using a mold. It is.

  (5) A fifth aspect of the present invention is a developing device including the developing roller according to any one of (1) to (3).

  (6) A sixth aspect of the present invention is an image forming apparatus comprising the developing roller according to any one of (1) to (3).

  In the present invention, a spiral groove having a lead angle in the axial direction is provided on the outer peripheral surface of the elastic layer, the axial distance between the spiral grooves is 0.01 mm or more and 0.3 mm or less, and the depth of the spiral groove Is 5 μm or more and 40 μm or less, the coating layer contains a filler, the particle diameter of the filler contained in the coating layer is 1 μm or more and 5 μm or less, and the thickness of the coating layer is 10 nm or more and 5000 nm or less It is a roller. By controlling the elastic layer to have the spiral grooves as described above and adjusting the particle size of the filler contained in the coating layer and the thickness of the coating layer to the above ranges, the occurrence of filming is well suppressed. It is possible to provide a developing roller excellent in environmental resistance and durable printing performance.

It is a drawing showing a developing roller of the present invention. It is a drawing showing a developing roller of the present invention. FIG. 1 is an explanatory view showing an example of an image forming apparatus in which a developing roller of the present invention is incorporated into a developing device.

  Hereinafter, embodiments of the present invention will be described in detail, but the following embodiments are presented for the purpose of illustration, and the present invention is not limited to the embodiments shown below.

<Developing roller>
The developing roller 1 of the present invention includes a shaft 2, an elastic layer 3 provided on the outer surface of the shaft 2, and a covering layer 4 provided outside the elastic layer 3.

[Shaft]
As the shaft 2, preferably, a shaft having conductivity can be used which is used in a conventionally known developing roller. The shaft 2 is preferably made of, for example, at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass. In addition, such an axial body 2 is generally known also by the name of "core metal."

  The shaft 2 may include an insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. The shaft 2 may include, for example, a core made of an insulating resin, and a plated layer provided on the core. Such a shaft 2 can be obtained, for example, by plating a core made of an insulating resin to make it conductive.

  The shaft 2 is preferably a cored bar in order to obtain good conductivity.

  The shape of the shaft 2 is preferably, for example, a rod, a tube, or the like. The cross-sectional shape of the shaft 2 may be, for example, a circle, an ellipse, or a non-circle such as a polygon. The outer peripheral surface of the shaft 2 may be subjected to treatments such as washing treatment, degreasing treatment, and primer treatment in order to improve the adhesion to the elastic layer 3.

  The length in the axial direction of the shaft 2 is not particularly limited, and may be appropriately adjusted according to the form of the image forming apparatus to be installed. For example, when the print target is A4 size, the axial length of the shaft 2 is preferably 250 mm or more and 320 mm or less, and more preferably 260 mm or more and 310 mm or less. Further, the diameter of the shaft 2 (diameter of the circumscribed circle) is not particularly limited, and may be appropriately adjusted according to the form of the image forming apparatus to be installed. For example, the outer diameter (diameter of the circumscribed circle) of the shaft body 2 is preferably 4 mm or more and 14 mm or less, and more preferably 6 mm or more and 10 mm or less.

[Elastic layer]
The elastic layer 3 has a spiral groove having a lead angle in the axial direction on the outer peripheral surface of the elastic layer 3, the axial distance between the spiral grooves is 0.01 mm or more and 0.3 mm or less, and the depth of the spiral groove is Is 5 μm or more and 40 μm or less. When the elastic layer has such a spiral groove, the surface of the developing roller 1 also has a spiral groove having a lead angle in the axial direction.

  Here, in the image forming apparatus 10 shown in FIG. 3, the developing roller 1 of the present invention can be used as the developer carrier 23. The developer 22 supplied to the developing roller 1 by the developer supplying roller (not shown) is adjusted to a desired amount while the surface of the developing roller 1 is scraped off by the developer regulating member 24 and conveyed to the image carrier 11 Be done. As in the conventional case, when unevenness is provided on the surface of the developing roller using a filler such as a resin particle having a relatively large particle diameter in order to secure the transport amount of the developer, the developing roller is scratched by the developer regulating member. At the time of removal, the convex portions on the surface of the developing roller apply a load to the developer to cause the developer to be crushed, which may cause filming, and the developer regulation member is scraped off with time. In some cases, cracks may occur in the convex portions of the developing roller. However, in the present invention, the elastic layer 3 has the helical groove having the lead angle in the axial direction adjusted to the above-mentioned interval and depth, thereby reducing the load on the developer 22 and causing filming. Thus, the local load on convex portions on the surface of the developing roller as in the prior art can be reduced, and the durability of the developing roller 1 can be improved. Furthermore, the load on the developer supply roller (not shown) that supplies the developer 22 to the development roller 1 in contact with the development roller 1 can be reduced, and the life of the developer supply roller can be extended. it can. Therefore, when the elastic layer 3 has the above-described spiral groove, the occurrence of filming can be favorably suppressed, and the durable printing performance can be improved.

  Further, the lead angle of the spiral groove is preferably 0.05 ° or more and 5 ° or less, and more preferably 0.1 ° or more and 3 ° or less.

  Further, as shown in FIG. 2, it is preferable that the winding direction of the spiral groove is reversed at a position less than 50% from the axial center point of the elastic layer 3 with respect to the entire axial length of the elastic layer 3. By reversing the direction of the spiral groove at the above position, it is possible to suppress the leakage of the developer from the developer seal member (not shown) that abuts on the developing roller 1 at the positions on both axial end sides of the developing roller 1 It is possible to improve the durable printing performance. From the viewpoint of further improving the durable printing performance, the winding direction of the spiral groove is reversed at a position of 0% or more and 20% or less from the axial center point of the elastic layer 3 with respect to the entire axial length of the elastic layer 3 It is more preferable that the winding direction of the spiral groove is reversed at a position of 0% or more and 10% or less from the axial center point of the elastic layer 3.

  The elastic layer 3 contains a cured product of a silicone rubber composition containing a conductivity imparting agent. The silicone rubber composition is a composition capable of forming an elastic body containing silicone rubber by curing, and may contain, for example, a silicone polymer capable of forming silicone rubber by crosslinking. Since the elastic layer 3 contains silicone rubber, the compression set can be reduced, and an effect of excellent flexibility in a low temperature environment can be obtained.

  Examples of the silicone rubber include crosslinked products of organopolysiloxanes such as dimethylpolysiloxane and diphenylpolysiloxane. Also, silicone rubber may be modified products of these.

  The conductivity imparting agent may be any component that can impart conductivity to the elastic layer 3. Examples of the conductivity imparting agent include metals, metal oxides (titanium oxide, tin oxide, zinc oxide and the like), conductive powders such as conductive polymers, carbon black, ion conductive agents, surfactants and the like.

  As the conductivity imparting agent, carbon black which is excellent in dispersibility and also excellent in reinforcement is particularly preferable. By blending carbon black with the ether-modified silicone oil into the silicone composition, the effects relating to the chargeability and the charge decay rate are more significantly exhibited. As a conductivity imparting agent, one type may be used alone, or two or more types may be used in combination. For example, in the silicone rubber composition, only carbon black may be used as a conductivity imparting agent, and carbon black and another conductivity imparting agent may be used in combination.

  The carbon black is not particularly limited, and, for example, acetylene black, furnace black, channel black, ketjen black, thermal black and the like are suitably used. As carbon black, one of these may be used alone, or two or more may be used in combination.

  The content of the conductivity imparting agent in the silicone rubber composition is preferably 0.5% by mass or more and 20% by mass or less, and is 1.0% by mass or more and 15% by mass or less based on the total mass of the silicone composition. It is more preferable that it is 2.0 mass% or more and 10 mass% or less. By adjusting the content of the conductivity imparting agent in the above range, the resistance value of the developing roller 1 becomes more stable, the printing performance is further improved, and the compression set of the elastic layer 3 becomes smaller, and the developing roller The durability of 1 is further improved.

  The silicone rubber composition may further contain various additives other than those described above. As various additives, for example, auxiliary agents (chain extenders, crosslinking agents, etc.), catalysts, dispersants, foaming agents, antiaging agents, antioxidants, fillers, pigments, colorants, processing aids, softeners And plasticizers, emulsifiers, heat resistance improvers, flame retardancy improvers, acid acceptors, heat conductivity improvers, mold release agents, solvents, reaction control agents and the like.

  The method for curing the silicone rubber composition is not particularly limited, and a known curing method may be adopted. For example, the silicone rubber composition may be cured by the addition of a vulcanizing agent and heating, or the crosslinking agent contained in the silicone rubber composition may be reacted by heating to cure.

  The silicone rubber composition may be, for example, an addition-curable millable conductive silicone rubber composition, an addition-curable liquid conductive silicone rubber composition, etc., but the addition-curable liquid conductive silicone rubber composition preferable.

(Addition-curable liquid conductive silicone rubber composition)
The addition-curable liquid conductive silicone rubber composition includes, for example, (D) an organopolysiloxane having two or more alkenyl groups in the molecule, and (E) two or more hydrogen atoms bonded to silicon atoms in the molecule. You may contain the organohydrogenpolysiloxane which it has, (F) filler, (G) electroconductivity imparting agent, and (H) addition reaction catalyst.

As the organopolysiloxane (D), a compound represented by the following average composition formula (2) is preferable.
R ⁴ _a SiO _{(4-a) / 2} (2)
In formula (2), a represents a positive number of 1.5 or more and 2.8 or less, preferably 1.8 or more and 2.5 or less, and more preferably 1.95 or more and 2.05 or less. Also, R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. However, at least two of R ^{4 in} one molecule are alkenyl groups. The carbon atom number of the hydrocarbon group is preferably 1 or more and 12 or less, and more preferably 1 or more and 8 or less.

As R ⁴ , the same groups as the groups exemplified as the above R ¹ can be exemplified. Preferably, at least two of R ^{4 in} one molecule are alkenyl groups, and the other R ⁴ is an alkyl group. The alkenyl group is preferably a vinyl group, and the alkyl group is preferably a methyl group. Moreover, 90% or more of R ⁴ may be, for example, an alkyl group (preferably a methyl group). The content of the alkenyl group in the (D) organopolysiloxane is, for example, preferably 1.0 × 10 ⁻⁶ mol / g or more and 5.0 × 10 ⁻³ mol / g or less, and 5.0 × 10 ⁻ or less. It is more preferable that they are ⁶ mol / g or more and 1.0 * 10 < ^-3 > mol / g or less.

  The organopolysiloxane (D) is preferably liquid at 25 ° C., and the viscosity at 25 ° C. is preferably 100 mPa · s or more and 1,000,000 mPa · s or less, and more preferably 200 mPa · s or more and 100000 mPa · s or less preferable. The average degree of polymerization of the (D) organopolysiloxane is preferably 100 or more and 800 or less, and more preferably 150 or more and 600 or less.

As the organohydrogenpolysiloxane (E), a compound represented by the following average composition formula (3) is preferable.
R ⁵ _b H _c SiO _{(4-b-c) / 2} (3)
In Formula (3), b shows a positive number of 0.7 or more and 2.1 or less, c shows a positive number of 0.001 or more and 1.0 or less, bc is 0.8 or more and 3.0 or less It is. Also, R ⁵ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. The carbon atom number of the hydrocarbon group is preferably 1 or more and 10 or less. As the R ^5, the same groups as in the above R ¹ may be exemplified.

  (E) The organohydrogenpolysiloxane has two or more hydrogen atoms (Si-H) bonded to a silicon atom in one molecule, and preferably has three or more hydrogen atoms. Further, the number of hydrogen atoms bonded to a silicon atom which one molecule of (E) organohydrogenpolysiloxane has is preferably 200 or less, more preferably 100 or less.

  In the organohydrogenpolysiloxane (E), the content of hydrogen atoms bonded to silicon atoms is preferably 0.001 mol / g to 0.017 mol / g, and more preferably 0.002 mol / g to 0.015 mol / g. It is more preferable that it is g or less.

(E) Organohydrogenpolysiloxanes, for example, methylhydrogenpolysiloxanes blocked by both terminal trimethylsiloxy groups, dimethylsiloxane / methylhydrogensiloxane copolymers blocked by both terminals trimethylsiloxy groups, dimethylhydrogensiloxy blocks by both terminals Dimethylpolysiloxane, Both terminal dimethylhydrogensiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer, Both terminal trimethylsiloxy group blocked methylhydrogensiloxane / diphenylsiloxane copolymer, Both terminal trimethylsiloxy group blocked methylhydrogensiloxane diphenylsiloxane-dimethylsiloxane _copolymers, copolymers consisting of _(CH 3) 2 _{HSiO 1/2} units and _{SiO 4/2} units, and, CH _{3) 2} HSiO _1/2 units and _{SiO 4/2} units and _{(C 6} H ₅₎ consisting of _{SiO 3/2} units, copolymers composed, and the like.

  The compounding amount of the (E) organohydrogenpolysiloxane is preferably 0.1 to 30 parts by mass, preferably 0.3 to 20 parts by mass, with respect to 100 parts by mass of the (D) organopolysiloxane. It is more preferable that Further, the molar ratio of Si-H of the (E) organohydrogenpolysiloxane to the alkenyl group of the (D) organopolysiloxane is preferably 0.3 to 5.0, and more preferably 0.5 to 2.5. It is more preferable that

  (F) The filler may be, for example, an inorganic filler. By blending the (F) filler with the addition-curable liquid conductive silicone rubber composition, the compression set becomes low, the volume resistivity becomes stable over time, and sufficient roller durability can be obtained.

  The average particle diameter of the filler (F) is preferably 1 μm or more and 30 μm or less, and more preferably 2 μm or more and 20 μm or less. (F) A temporal change in volume resistivity is further suppressed when the average particle diameter of the filler is 1 μm or more. Moreover, the elastic layer 3 which is further excellent in durability can be obtained as the average particle diameter of (F) filler is 30 micrometers or less. In addition, the average particle diameter of (F) filler can be measured as a median diameter using the particle size distribution measuring apparatus by a laser beam diffraction method.

(F) the bulk density of the filler is preferably at 0.1 g / cm ³ or more 0.5 g / cm ³ or less, and more preferably less 0.15 g / cm ³ or more 0.45 g / cm ³ . (F) By adjusting the bulk density of the filler to the above range, the compression set can be further lowered, the temporal change of the volume resistivity is further suppressed, and the elastic layer 3 is further excellent in the durability. You can get (F) The bulk density of the filler can be determined based on the method of measuring apparent specific gravity according to JIS K 6223.

  Examples of the filler (F) include diatomaceous earth, perlite, mica, calcium carbonate, glass flakes and hollow fillers. Among these, as the (F) filler, pulverized materials of diatomaceous earth, perlite and expanded perlite can be suitably used. In addition, silica-based fillers such as fumed silica can also be used.

  The blending amount of the (F) filler is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the (D) organopolysiloxane. .

  The blending amount of the (G) conductivity imparting agent is preferably 0.5 parts by mass or more and 15 parts by mass or less, and 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the (D) organopolysiloxane. It is more preferable that

  The (H) addition reaction catalyst may be any catalyst that can activate the addition reaction of (D) organopolysiloxane and (E) organohydrogenpolysiloxane. Examples of the (H) addition reaction catalyst include catalysts having a platinum group element. Examples of the catalyst having a platinum group element include platinum-based catalysts (eg, platinum black, platinum chloride, platinum chloride, chloroplatinic acid, reaction product of chloroplatinic acid and monohydric alcohol, and complexes of chloroplatinic acid and olefins And platinum bisacetoacetate etc., palladium based catalysts, rhodium based catalysts and the like.

  (H) The addition amount of the addition reaction catalyst may be a catalytic amount. For example, the compounding amount of (H) addition reaction catalyst is such that the amount of platinum group element is 0.5 mass ppm or more and 1000 mass ppm or less based on the total mass of (D) organopolysiloxane and (E) organohydrogenpolysiloxane The amount is preferably such as to be 1 mass ppm or more and 500 mass ppm or less.

  The addition-curable liquid conductive silicone rubber composition may further contain an additive other than (D) to (H). Examples of additives include auxiliary agents (chain extenders, crosslinking agents, etc.), foaming agents, dispersing agents, anti-aging agents, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, Examples thereof include heat resistance improvers, flame retardancy improvers, acid acceptors, heat conductivity improvers, mold release agents, diluents, reactive diluents, solvents and the like.

  Specific examples of the additive include dispersants such as low molecular weight siloxane ester, polyether modified silicone oil, silanol and phenylsilanediol. In addition, heat resistance improvers such as iron octylate, iron oxide, cerium oxide and the like can be mentioned. In addition, various carbon functional silanes, various olefin elastomers, and the like may be used to improve adhesion, molding processability, and the like. Further, a halogen compound or the like which imparts flame retardancy may be used.

  The viscosity at 25 ° C. of the addition-curable liquid conductive silicone rubber composition is preferably 5 Pa · s or more and 500 Pa · s or less, and more preferably 5 Pa · s or more and 200 Pa · s or less.

  The thickness of the elastic layer 3 is not particularly limited, and is preferably 0.1 mm or more and 6 mm or less, and more preferably 1 mm or more and 4 mm or less. The thickness in the present specification indicates the thickness in the direction perpendicular to the axial direction of the developing roller 1.

  The outer diameter of the elastic layer 3 is not particularly limited, and is, for example, preferably 6 mm or more and 25 mm or less, and more preferably 7 mm or more and 21 mm.

  The elastic layer 3 is formed by disposing the silicone rubber composition on the outer peripheral surface of the shaft body 2 and curing the silicone rubber composition. The curing method of the silicone rubber composition may be any method capable of applying the heat necessary for curing of the silicone rubber composition, but in the present invention, since the elastic layer 3 has the above-mentioned spiral groove, a spiral having a lead angle It is preferable to form by injection molding using the metal mold which provided the continuous convex part of the shape in the surface. Since the elastic layer 3 is formed by curing with a mold, a region in contact with the spiral continuous convex portion of the mold is formed as a spiral groove of the elastic layer 3. In addition, the lead angle of the spiral convex portion of the mold is 0.05 ° or more and 5 ° or less, and the difference between the height of the convex portion and the concave portion is 5 μm or more and 100 μm or less. The pitch) is preferably 0.01 mm or more and 0.3 mm or less.

  In the case of the addition-curable liquid conductive silicone rubber composition, the heating temperature and the heating time for curing the silicone rubber composition are 100 ° C. or more and 300 ° C. or less, particularly 110 ° C. or more and 200 ° C. or less Is more preferably several seconds to one hour, and more preferably 10 seconds to 35 minutes. In addition, you may provide the process of secondary vulcanization.

  The outer peripheral surface of the elastic layer 3 is subjected to surface treatment such as primer treatment, corona treatment, plasma treatment, excimer treatment, UV treatment, itro treatment, frame treatment, etc. for the purpose of improving adhesion with the coating layer 4 and the like. May be

[Covering layer]
The covering layer 4 is provided on the outermost surface of the developing roller 1. The coating layer 4 applies the resin composition to the outer peripheral surface of the elastic layer 3 thus formed or the primer layer optionally formed, and then the applied resin composition is heated and cured. Let it be formed. In addition, it is not necessary to form the coating layer 4 by heating and curing the resin composition, but it may be performed by silicone coating treatment using ethyl silicate, treatment including a titanium-based, aluminum-based, zirconium-based material, etc. It may be a layer to be formed.

  The thickness of the covering layer 4 is 10 nm or more and 5000 nm or less. Filming is performed by adjusting the thickness of the covering layer 4 within the above range so that the spiral groove is provided on the surface of the developing roller 1 while adjusting the depth of the spiral groove of the elastic layer 3 within the above range. Can be improved while durable printing performance can be improved.

  The resin composition for forming the covering layer 4 contains a precursor for forming a resin, a conductivity imparting agent, and, if desired, various additives. As the resin, various ones may be mentioned, and among them, urethane resin is preferable. The urethane preparation component which is a precursor which forms a urethane resin should just form a urethane resin, for example, the mixture of a polyol and isocyanate is mentioned.

  The polyol may be any of various polyols commonly used in polyurethane preparation, and is preferably at least one polyol selected from polyether polyols, polyester polyols, polyacrylate polyols, and polycarbonate polyols.

  Polyether polyols include, for example, polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polypropylene glycol-ethylene glycol, polytetramethylene ether glycol, copolymerized polyols of tetrahydrofuran and alkylene oxide, and various modified products of these or these A mixture etc. are mentioned.

  Polyester polyols have two or more ester bonds and two or more hydroxyl groups in the molecule. As a polyester polyol, the condensation reaction product of dicarboxylic acid and a polyol etc. are mentioned, for example. Examples of dicarboxylic acids include aromatic dicarboxylic acids such as phthalic acid, terephthalic acid and isophthalic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid.

  Polyacrylate polyols are hydroxyl group-containing monomers and other olefinically unsaturated monomers such as esters of (meth) acrylic acid, styrene, α-methylstyrene, vinyl toluene, vinyl esters, monoalkyl esters of maleic acid and dialkyl esters of maleic acid And fumaric acid monoalkyl esters and fumaric acid dialkyl esters, α-olefins and copolymers with other unsaturated oligomers and unsaturated polymers.

  Polycarbonate polyols have two or more carbonate bonds and two or more hydroxyl groups in the molecule. As a polycarbonate polyol, the condensation reaction product of a polyol and a carbonate compound etc. are mentioned, for example. Moreover, as a carbonate compound, a dialkyl carbonate, a diaryl carbonate, an alkylene carbonate etc. are mentioned, for example. Examples of the polyol used as a raw material of polycarbonate polyol include diols such as hexanediol and butanediol, and triols such as 2,4-butanetriol.

  The isocyanate may be any of the various isocyanates commonly used in the preparation of polyurethanes, and examples thereof include aliphatic isocyanates, aromatic isocyanates and derivatives thereof. The isocyanate is preferably an aliphatic isocyanate in terms of excellent storage stability and easy control of the reaction rate. As aromatic isocyanate, for example, xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (also referred to as tolylene diisocyanate. TDI), 3,3′-bitrylene-4,4′-diisocyanate, 3, 3'-Dimethyldiphenylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate uretidinedione (dimer of 2,4-TDI), xylene diisocyanate, naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PDI) , Tolidine diisocyanate (TODI), metaphenylene diisocyanate and the like. Examples of aliphatic isocyanates include hexamethylene diisocyanate (HDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), ortho toluidine diisocyanate, lysine diisocyanate methyl ester, isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, trans cyclohexane -1, 4- diisocyanate, triphenylmethane 4, 4 ', 4' '-triisocyanate etc. are mentioned. As derivatives, polynuclear bodies of polyisocyanate, urethane-modified products (including urethane prepolymers) modified with polyols, etc., dimers due to urethidione formation, isocyanurate modified products, carbodiimide modified products, uretonimine modified products, allophanate modified products, Urea modified products, burette modified products, etc. may be mentioned. The polyisocyanate can be used alone or in combination of two or more. The polyisocyanate preferably has a molecular weight of 500 to 2000, more preferably 700 to 1500.

  The mixing ratio in the mixture of the polyol and the polyisocyanate is not particularly limited, but the molar ratio (NCO / OH) of the hydroxyl group (OH) contained in the polyol and the isocyanate group (NCO) contained in the polyisocyanate is usually 0 It is preferable that the ratio be 7 or more and 1.15 or less. The molar ratio (NCO / OH) is more preferably 0.85 or more and 1.10 or less in that the polyurethane hydrolysis can be prevented. In practice, an amount equivalent to three to four times the appropriate molar ratio may be blended in consideration of work environment and work errors.

  In the urethane preparation component, in addition to the polyol and the polyisocyanate, an auxiliary agent generally used for the reaction of the polyol and the polyisocyanate may be used in combination, for example, a chain extender, a crosslinking agent and the like. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane and amines.

  Coating of the resin composition can be performed, for example, by a coating method of coating a coating liquid of a resin composition, a dipping method of immersing the elastic layer 3 and the like in the coating liquid, and spray coating of spraying the coating liquid on the elastic layer 3 and the like. It is carried out by a known coating method such as a method. The resin composition may be coated as it is or, for example, alcohols such as methanol and ethanol, aromatic solvents such as xylene and toluene, ester solvents such as ethyl acetate and butyl acetate, etc. You may coat the coating liquid which added the volatile solvent or water. The method of curing the resin composition applied in this manner may be any method as long as it can add heat or moisture necessary for curing of the resin composition, for example, an elastic layer coated with the resin composition The method of heating 3 grade | etc., With a heater, the method of leaving elastic layer 3 grade | etc., With which the resin composition was coated under high humidity, etc. are mentioned. The heating temperature when heat curing the resin composition is, for example, preferably 100 ° C. or more and 200 ° C. or less, particularly preferably 120 ° C. or more and 160 ° C. or less, and the heating time is 10 minutes or more and 120 minutes or less Is preferably, and more preferably 30 minutes or more and 60 minutes or less. In addition, instead of coating, the resin composition is laminated on the outer peripheral surface of the elastic layer 3 or the primer layer by a known molding method such as extrusion molding, press molding, injection molding or the like, or after lamination. A method of curing the resin composition may be employed.

  In the covering layer 4 formed in this manner, the precursor for forming the resin and the conductivity imparting agent may react with each other to form an integral body or a complex, and the conductivity imparting agent It may be dispersed in the resin without reacting with the precursor forming the resin.

In addition, the coating layer 4 contains a filler as an additive, and the particle diameter of the filler is 1 μm or more and 5 μm or less, preferably 1.5 μm or more and 4.5 μm or less, and 1.5 μm or more. More preferably, it is 0 μm or less. When the covering layer 4 contains a filler having a particle diameter in the above range, the load on the surface of the developing roller 1 can be reduced as compared with the case where a filler having a large particle diameter is used, and generation of filming occurs. Can be suppressed. Further, by setting the particle diameter of the filler contained in the covering layer 4 in the above range, the adhesion of the surface of the developing roller 1 can be reduced, and the case of using for a long time under high temperature and high humidity Also, the sticking of the developer to the surface of the developing roller 1 can be reduced. As a result, even when used for a long time under high temperature and high humidity, the developer carrying force of the developing roller 1 can be maintained, and it is possible to prevent the reduction of the printing density and the nonuniformity of the image. The developing roller 1 excellent in environmental resistance and durable printing performance can be obtained. In addition, the filler used for said elastic layer 3 can also be used as a filler. In addition, content of the filler contained in a coating layer is 2 with respect to 100 mass parts of urethane preparation components.
It is preferable that it is mass part or more and 20 mass parts or less, and it is more preferable that it is 5 mass parts or more and 15 mass parts or less.

(MD-1 hardness)
In the present invention, the MD-1 hardness of the surface of the developing roller 1 is preferably 20 or more and 60 or less, and more preferably 30 or more and 50 or less. By adjusting the MD-1 hardness of the surface of the developing roller 1 to the above range, it is possible to maintain the transport amount of the developer 42 while reducing the load on the developer 42. For measurement of the MD-1 hardness, use the MD-1 hardness tester ("Micro rubber hardness tester MD-1" manufactured by Kobunshi Keiki Co., Ltd.) Press the needle of the MD-1 hardness tester on the roll surface, and peak The hold mode and the hold time are values read at 3 seconds as the MD-1 hardness, and the MD-1 hardness tester basically conforms to the type A durometer described in JIS K6253.

<Method of manufacturing developing roller>
The developing roller 1 of the present invention comprises a first step of forming the elastic layer 3 on the outer peripheral surface of the shaft 2 and a second step of forming the covering layer 4 provided on the outer side of the elastic layer 3. It can be manufactured by In the first step, it is preferable to use injection molding using a mold. For the detailed conditions in each step, refer to the above.

<Developing device and image forming device>
The developing roller 1 according to the present embodiment can be suitably used as the developer carrier 23 in the developing device and the image forming apparatus. In the present embodiment, the configuration other than the developing roller 1 in the image forming apparatus is not particularly limited. An example of a developing device and an image forming apparatus provided with the developing roller 1 of the present invention will be described with reference to FIG.

  The image forming apparatus 10 is a tandem type color image forming apparatus in which a plurality of image carriers 11B, 11C, 11M and 11Y installed in developing units B, C, M and Y of respective colors are arranged in series on the transfer conveyance belt 6 The developing units B, C, M, and Y are disposed in series on the transfer conveyance belt 6. The developing unit B includes an image carrier 11B such as a photosensitive member (also referred to as a photosensitive drum), a charging unit 12B such as a charging roller, an exposure unit 13B, a developing device 20B, and an image carrying unit The transfer means 14B, for example, a transfer roller, which abuts the body 11B, and a cleaning means 15B are provided.

  The developing device 20B is an example of the developing device of the present invention, and as shown in FIG. 3, includes the developing roller of the present invention and a developer. Therefore, in the image forming apparatus 10, the developing roller 1 is mounted as the developer carrier 23B, 23C, 23M and 23Y, that is, as a developing roller. Specifically, the developing device 20B includes a case 21B for containing a one-component nonmagnetic developer 22B, a developer carrier 23B for supplying the developer 22B to the image carrier 11B, for example, a developing roller, and a developer 22B. And a developer amount adjusting means 24B for adjusting the thickness of the toner. In the developing device 20B, as shown in FIG. 3, the developer amount adjusting means 24B is in contact with or in pressure contact with the outer peripheral surface of the developer carrier 23B. That is, the developing device 20B is a so-called "contact type developing device". The developing units C, M and Y are basically configured in the same manner as the developing unit B, and the same elements are given the same reference numerals and symbols C, M or Y indicating the respective units, and the description will be omitted. .

  In the image forming apparatus 10, the developer carrier 23B of the developing device 20B is disposed such that the surface thereof is in contact with or in pressure contact with the surface of the image carrier 11B. Similarly to the developing device 20B, the developing devices 20C, 20M and 20Y are arranged such that the developer carrier 23C, 23M and 23Y is in contact with or in pressure contact with the surfaces of the image carriers 11C, 11M and 11Y. . That is, the image forming apparatus 10 is a so-called "contact image forming apparatus".

  The fixing unit 30 is disposed downstream of the developing unit Y. The fixing unit 30 includes a fixing roller 31, an endless belt supporting roller 33 disposed in the vicinity of the fixing roller 31, a fixing roller 31 and an endless belt supporting roller in a housing having an opening 35 through which the recording medium 16 passes. An endless belt 36 wound around the belt 33 and a pressure roller 32 disposed opposite to the fixing roller 31 so that the fixing roller 31 and the pressure roller 32 contact or press each other via the endless belt 36 The pressure heat fixing device is rotatably supported by the At the bottom of the image forming apparatus 10, a cassette 41 for storing the recording material 16 is installed. The transfer conveyance belt 6 is wound around a plurality of support rollers 42.

  The developers 22B, 22C, 22M and 22Y used in the image forming apparatus 10 may be either dry developers or wet developers as long as they can be charged by friction, and magnetic development is possible even with non-magnetic developers. It may be an agent. The single-component nonmagnetic black developer 22B, cyan developer 22C, magenta developer 22M and yellow developer 22Y are accommodated in the housings 21B, 21C, 21M and 21Y of the respective developing units.

  The image forming apparatus 10 forms a color image on the recording material 16 as follows. First, in the developing unit B, an electrostatic latent image is formed by the exposure unit 13B on the surface of the image carrier 11B charged by the charging unit 12B, and a black electrostatic latent image is formed by the developer 22B supplied by the developer carrier 23B. The image is developed. Then, when the recording material 16 passes between the transfer means 14B and the image carrier 11B, a black electrostatic latent image is transferred onto the surface of the recording material 16B. Subsequently, in the same manner as in the developing unit B, the cyan image, the magenta image and the yellow image are respectively superimposed on the recording material 16 in which the electrostatic latent image is made a black image by the developing units C, M and Y. The color image is visualized. Next, the fixing device 30 fixes the color image to the recording medium 16 as a permanent image, as the recording medium 16 in which the color image is developed. In this manner, a color image can be formed on the recording body 16.

  The developing device is provided with the developing roller 1 and is excellent in developer transportability, and can suppress the occurrence of toner filming, thereby contributing to forming a high density and high quality image over a long period of time. Further, this image forming apparatus can form high density and high quality images over a long period of time.

  The developing device and the image forming apparatus of the present invention are not limited to those described above, and various modifications can be made as long as the object of the present invention can be achieved.

  Although the image forming apparatus 10 is an electrophotographic image forming apparatus, in the present invention, the image forming apparatus is not limited to the electrophotographic system, and may be, for example, an electrostatic image forming apparatus. Good. Further, the image forming apparatus in which the developing roller of the present invention is disposed is not limited to a tandem type color image forming apparatus in which a plurality of image carriers having developing units of respective colors are arranged in series on a transfer conveyance belt. The image forming apparatus may be a monochrome image forming apparatus having a single developing unit, or a four-cycle color image forming apparatus in which a developer image carried on an image carrier is sequentially sequentially transferred onto an endless belt. The developer used in the image forming apparatus 10 is a one-component nonmagnetic developer, but in the present invention, it may be a one-component magnetic developer or a two-component nonmagnetic developer. Also, it may be a two-component magnetic developer.

  The image forming apparatus 10 is a so-called "contact image forming apparatus". In the present invention, the image forming apparatus is disposed with a gap so that the surface of the developer carrier does not contact the surface of the image carrier. It may be a so-called "non-contact type image forming apparatus".

  Although the present invention has been described above using the embodiment, it goes without saying that the technical scope of the present invention is not limited to the scope of the invention described in the above embodiment, and various modifications or changes may be made to the above embodiment. It will be apparent to one skilled in the art that improvements can be made. It is also apparent from the scope of the claims that the invention added with such changes or improvements can be included in the technical scope of the present invention.

  Hereinafter, the present invention will be described in detail by way of examples. The present invention is not limited to the examples shown below.

Example 1
The electroless nickel plated shaft (made by SUM22, diameter 10 mm, length 275 mm) is washed with ethanol, and a silicone primer (brand name “Primer No. 16”, Shin-Etsu Chemical Co., Ltd.) It applied. The primer-treated shaft was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at normal temperature for 30 minutes or more to form a primer layer on the outer peripheral surface of the shaft.

Then, a silicone rubber composition for forming an elastic layer was prepared as follows. That is, hydrophobized fumed silica having 100 parts by mass of dimethylpolysiloxane (polymerization degree: 300) blocked at both ends with dimethylvinylsiloxy group and a BET specific surface area of 110 m ² / g (trade name “R-972” 1 part by mass of Nippon Aerosil Co., Ltd., 40 parts by mass of diatomaceous earth (trade name “Oplite W-3005S”, made of central silica) having an average particle diameter of 6 μm and a bulk density of 0.25 g / cm ³ , and acetylene black 5 parts by mass (trade name "Denka black HS-100", manufactured by Denka), 1 part by mass of side chain ether-modified silicone oil (trade name "KF-644" manufactured by Shin-Etsu Chemical Co., Ltd.) in a planetary mixer After stirring, it was passed through three rolls once. This is returned to the planetary mixer again, and 2.1 parts by mass of methylhydrogenpolysiloxane having Si-H groups at both ends and side chains (polymerization degree 17, Si-H amount 0.0060 mol / g), ethynyl cyclohexanol 0.1 parts by mass and 0.1 parts by mass of a platinum catalyst (Pt concentration: 1%) were added, and the mixture was stirred for defoaming and kneading for 30 minutes to prepare an addition-curable liquid conductive silicone rubber composition.

  The prepared addition-curable liquid conductive silicone rubber composition was injection-molded using a mold to form an elastic body made of a rubber material on the outer peripheral surface of the shaft. In addition, the metal mold which provided the helical continuous convex part which has a lead angle as a metal mold was used on the surface. In the injection molding, an addition-curable liquid conductive silicone rubber composition was heated at 150 ° C. for 10 minutes to be cured, and secondary vulcanization at 200 ° C. for 4 hours was performed to form an elastic layer having an outer diameter of 16 mm. The lead angle of the elastic layer was 0.78 °, the axial interval of the spiral grooves was 0.22 mm, and the depth of the spiral grooves was 20 μm.

Next, a resin composition for forming a coating layer was prepared as follows.
・ 28 parts by mass of polyacrylate polyol (molar ratio of hexamethylene diisocyanate to polyacrylate polyol described later (NCO / OH = 1.1 / 1)
Carbon black (trade name "Toca Black # 5500", 5 parts by mass made by Tokai Carbon Co., Ltd.) Small diameter silica as a filler (average particle diameter 4.4 μm, trade name "ACEMATT OK-607, manufactured by Evonik Co., Ltd.) 4 Mass part (9.5 mass parts to 100 mass parts of polyurethane preparation ingredients)
-Dibutyltin diurarate (trade name "Di-n-butyltin diurarate", 0.03 parts by mass)-Hexamethylene diisocyanate (trade name "Duranate TPA-100", manufactured by Asahi Kasei Corp.) 14 parts by mass-Dilution Thinner as solvent 100 parts by mass

  The resin composition was applied to the outer peripheral surface of the elastic layer 3 by a spray coating method, and heated at 160 ° C. for 30 minutes to form a coating layer having a layer thickness of 2000 nm. Thus, a developing roller provided with a shaft, an elastic layer and a covering layer was produced.

(Example 2)
Example except using the mold different from Example 1, adjusting the lead angle of the elastic layer to 0.42 °, the axial interval of the spiral groove to 0.12 mm, and the depth of the spiral groove to 20 μm The developing roller of Example 2 was obtained in the same manner as in No. 1.

(Example 3)
The lead angle of the elastic layer, the axial interval of the spiral groove, and the depth of the spiral groove are adjusted in the same manner as in Example 2, and further, the filler used for the coating layer is small diameter silica (average particle diameter 1.5 μm, The developing roller of Example 3 was obtained by the same method as that of Example 1 except that it was changed to a trade name "Sea Hoster KE-P150" (manufactured by Nippon Shokubai Co., Ltd.) and the layer thickness of the coating layer was 1000 nm.

(Comparative example 1)
In the formation of the elastic layer, a method similar to that of Example 1 is used except that a mold having a smooth surface without the above-mentioned helical convex portion is used, and the small diameter silica is made to be 0 parts by mass in the covering layer. Thus, the developing roller of Comparative Example 1 was obtained.

(Comparative example 2)
In molding of the elastic layer, a mold having a smooth surface without the above-mentioned helical convex portion is used, and further, urethane resin particles (average particle diameter 15 μm, goods are used instead of small diameter silica as a filler of the coating layer A developing roller of Comparative Example 2 was obtained in the same manner as in Example 1 except that the name "Art Pearl P-400" (manufactured by Negami Chemical Industries, Ltd.) was used.

  Next, an image forming apparatus C610dn2 (model number, manufactured by Oki Data Co., Ltd.) was prepared, and the developing roller of this image forming apparatus was replaced with the developing roller of each example and each comparative example to obtain an image forming apparatus. With respect to the obtained image forming apparatus, evaluation of filming, evaluation of printing density, and evaluation of image uniformity were respectively performed by the following method, and the results are shown in Table 1.

<Evaluation of filming>
Filming weight measurement after suctioning the developer adhering to the surface of the developing roller after printing 6000 sheets under the conditions of temperature 23 ° C. and humidity 55% RH using the image forming apparatus equipped with the prepared developing roller The mass transferred to the jig was measured. For filming evaluation, the mass of the transferred developer was evaluated according to the following criteria. In the present test, the filming amount is passed when the evaluation is B.
A: 0 mg or more and less than 0.02 mg B: 0.02 mg or more and less than 0.05 mg C: 0.05 mg or more

<Evaluation of print density>
Solid images are printed under conditions of temperature 23 ° C., humidity 55% RH, temperature 30 ° C., humidity 80% RH, room temperature 10 ° C., humidity 20% RH, and made by X-Rite The print density of the solid image was measured using a 508 densitometer. Specifically, 1.4 1.4 or more and ○ less than 1.4.

<Evaluation of image uniformity>
A solid image is printed under conditions of temperature 23 ° C. and humidity 55% RH, temperature 30 ° C. and humidity 80% RH, temperature 10 ° C. and humidity 20% RH, and the first print density And the print density of the 2000th sheet were compared. Specifically, when the density step ratio between the initial print forming portion and the final print forming portion of solid printing is within 1.1, it is 、, when it is within 1.2, it is ○, and when it is larger than 1.2, x And

<Evaluation>
From the above, it can be seen that according to the present invention, it is possible to obtain a developing roller and an image forming apparatus including the developing roller, and a developing roller excellent in environmental resistance and durable printing performance while filming generation is favorably suppressed. .

DESCRIPTION OF SYMBOLS 1 developing roller 2 axis body 3 elastic layer 4 coating layer 6 transfer conveyance belt 10 image forming apparatus 11B, 11C, 11M, 11Y image carrier 12B, 12C, 12M, 12Y charging means 13B, 13C, 13M, 13Y exposure means 14B, 14C, 14M, 14Y Transfer means 15B, 15C, 15M, 15Y Cleaning means 16 Recording body 20 Developing device 21B, 21C, 21M, 21Y, 34 Casing 22B, 22C, 22M, 22Y Developer 23B, 23C, 23M, Development Agent carrier 24B, 24C, 24M, 24Y Developer regulation member 30 Fixing means 31 Fixing roller 32 Pressure roller 33 Endless belt support roller 35 Opening 36 Endless belt 41 Cassette 42 Support roller B, C, M, Y Development unit

Claims (6)

A developing roller comprising: a shaft; an elastic layer provided on an outer peripheral surface of the shaft; and a covering layer provided outside the elastic layer,
The outer peripheral surface of the elastic layer has a spiral groove having a lead angle in the axial direction,
An axial interval of the spiral groove is 0.01 mm or more and 0.3 mm or less,
The depth of the spiral groove is 5 μm or more and 40 μm or less,
The coating layer contains a filler, and the particle size of the filler contained in the coating layer is 1 μm to 5 μm,
The developing roller, wherein the thickness of the covering layer is 10 nm or more and 5000 nm or less.   The developing roller according to claim 1, wherein the MD-1 hardness of the surface of the developing roller is 20 or more and 60 or less.   3. The winding direction of the spiral groove is reversed at a position less than 50% from the axial center point of the elastic layer with respect to the axial entire length of the elastic layer. The developing roller described in. A method of manufacturing the developing roller according to any one of claims 1 to 3, wherein
A first step of forming an elastic layer on the outer peripheral surface of the shaft;
And a second step of forming the covering layer provided on the outer side of the elastic layer,
In the first step, a method of manufacturing a developing roller, comprising injection molding using a mold.   A developing device comprising the developing roller according to any one of claims 1 to 3.   An image forming apparatus comprising the developing roller according to any one of claims 1 to 3.