JP2006023702A - Developing roller and image forming apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight developing roller capable of reliably and stably giving high quality images free of white image fogging without causing image change or image unevenness over time even in continuous printing or in partial solid image printing, and to provide an image forming apparatus with the developing roller. <P>SOLUTION: The developing roller 1 has a shaft member 2 comprising a hollow or solid cylinder made of a resin containing a conductive agent and one or more resin layers 4 disposed on the radial outside of the shaft member. When a roller periphery is charged by causing corona discharge by applying a voltage of 8 kV to a corona discharger 42 disposed at an interval of 1 mm from the roller periphery, the absolute value of surface potential decay speed in a range from 0.1 s to 0.2 s after imparting charges is ≥0.1 [V/s]. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing roller used in an image forming apparatus such as an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus, and an image forming apparatus using the developing roller.

  In an electrophotographic image forming apparatus such as a copying machine or a printer, a nonmagnetic developer (toner) is supplied to a latent image holding body such as a photosensitive drum holding a latent image, and toner is applied to the latent image on the latent image holding body. The latent image is visualized by adhering, and as one of the general development methods, on the outer periphery of the developing roller arranged with a small gap between the latent image holding member and the latent image holding member. There is a non-magnetic jumping development method in which charged toner is carried, and the developing roller is rotated in a state where a voltage is applied between the latent image holding member and the developing roller, thereby causing the toner to fly to the latent image holding member.

  The nonmagnetic jumping development method will be further described with reference to FIG. A small gap 92 is provided with respect to the photosensitive drum 95 between the toner supply roller 94 for supplying the toner and the photosensitive drum (latent image holding member) 95 holding the electrostatic latent image. The developing roller 91, the photosensitive drum 95, and the toner supply roller 94 rotate in the directions of the arrows in the drawing, and a predetermined voltage is applied between the photosensitive drum 95 and the developing roller 91. The toner 96 is supplied to the surface of the developing roller 91 by the toner supply roller 94, the toner 96 is adjusted to a uniform thin layer by the stratifying blade 97, and the toner 96 formed in the thin layer is exposed to the gap 92. It flies to the drum 95 and adheres to the latent image, and this latent image is visualized.

  In the figure, reference numeral 98 denotes a transfer unit, which transfers a toner image onto a recording medium such as paper. A cleaning unit 99 is configured to remove the toner 6 remaining on the surface of the photosensitive drum 95 after the transfer by the cleaning blade 99a.

FIG. 2 is a cross-sectional view showing a conventional developing roller 91 used in the non-magnetic jumping development method. The developing roller 91 is generally a solid cylindrical or hollow cylindrical shaft made of a highly conductive material. A resin layer 84 is provided on the outer periphery of the member 82 (shown in the form of a solid cylinder) to optimize the chargeability and adhesion to the toner or the frictional force between the developing roller and the stratified blade. (For example, refer patent document 1).

The shaft member 82 is preferably made of resin in order to reduce the weight as long as it is permitted in terms of strength. In that case, the roller main body portion 85 and shaft portions 86a constituting both end portions in the length direction of the shaft member 82 are used. The shaft portion 86a is pivotally supported by a roller support portion of the image forming apparatus.
JP 2002-14534 A

  However, in order to obtain a high-quality image by image formation using the developing roller, the developer held on the developing roller always maintains a constant charge when reaching the latent image holding member, and has a uniform charged state. However, the charge amount of the toner carried on the developing roller may become unstable during continuous printing, for example, the toner on the developing roller in an undeveloped portion is continuously There is a case where frictional charging occurs and the charge amount exceeds a predetermined value. In addition, when a solid black image is printed, the charge amount of the developer newly held in that part may be different from the surroundings, and this is caused by non-uniformity of the developer charge distribution caused by this. In some cases, uniform image defects may occur, and it is extremely important to prevent such problems particularly when high image quality is required for an image forming apparatus such as a printer or when trying to cope with color images. It was.

  The present invention has been made in view of such problems, and there is no occurrence of white image fog, without causing temporal image change or image unevenness even during continuous printing or partial solid image printing. An object of the present invention is to provide a developing roller capable of reliably and stably obtaining a high-quality image and an image forming apparatus including the developing roller.

<1> In the present invention, one or more resin layers are provided on the outer side in the radial direction of a shaft member that is attached by being axially supported at both ends in the length direction, and the nonmagnetic developer carried on the outer peripheral surface is held as a latent image. In the developing roller supplied to the body,
The shaft member is made of a hollow hollow cylinder made of a resin containing a conductive agent or a solid cylindrical body, and a voltage of 8 kV is applied to a corona discharger disposed at a distance of 1 mm from the outer peripheral surface. When the corona discharge is generated to charge the outer peripheral surface, the absolute value of the surface potential decay rate from 0.1 seconds to 0.2 seconds after the charge is applied is 0.1 [V / sec] or more. A developing roller.

<2> The present invention is the developing roller according to <1>, wherein at least one resin layer is made of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent.
In this specification, the electron beam curable resin does not contain a crosslinking agent, a polymerization initiator, or a cleavage aid, and has the property of allowing self-crosslinking to proceed with energy by electron beam irradiation without using these aids. It shall mean the resin it has. However, in actual production, these may be blended with a crosslinking agent or the like to form a layer, and the electron beam curable resin does not refuse to blend them with the crosslinking agent or the like.

  <3> In the present invention, in <1> or <2>, the resin layer made of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent is coated with a solventless coating solution, and ultraviolet or electronic It is a developing roller formed by irradiating a line.

  <4> The present invention is the developing roller according to any one of <1> to <3>, wherein an elastic layer is disposed between the shaft member and the innermost resin layer.

  <5> In the present invention, in any one of <1> to <4>, the resin forming the shaft member is at least one kind selected from the group consisting of general-purpose resins, general-purpose engineering plastics, and super-engineering plastics. A developing roller made of resin.

  <6> The present invention relates to <5>, wherein the general-purpose engineering plastic or super engineering plastic is polyacetal, polyamide 6, polyamide 6, 6, polyamide 12, polyamide 4, 6, polyamide 6, 10, polyamide 6, 12, polyamide 11, polyamide MXD6, polybutylene terephthalate, polyphenylene oxide, polyphenylene sulfide, polyphenylene ether, polyether sulfone, polycarbonate, polyimide, polyamide imide, polyether imide, polysulfone, polyether ether ketone, polyethylene terephthalate, polyarylate polytetrafluoroethylene, Alternatively, the developing roller is a liquid crystal polymer.

  <7> In the present invention, in any one of <1> to <6>, the conductive agent contained in the resin forming the shaft member is carbon black, graphite, tin oxide, titanium oxide, zinc oxide, nickel, aluminum And a developing roller that is at least one selected from the group consisting of copper.

  <8> The present invention provides the reinforcement according to any one of <1> to <7>, wherein the shaft member is formed of a hollow cylindrical body, and extends from the outer peripheral surface toward the radially inner side of the hollow cylindrical body. This is a developing roller provided with a working rib.

  <9> The present invention provides the shaft member according to <8>, wherein the shaft member is provided with a metal shaft that is disposed at a center in the radial direction of the hollow cylindrical body and passes through the hollow cylindrical body. A developing roller configured to support an end.

  <10> The present invention is the developing roller according to <9>, wherein the hollow cylindrical body is configured by connecting a plurality of cylindrical members in the length direction.

  <11> The present invention is an image forming apparatus provided with the developing roller according to any one of <1> to <10>.

  According to the invention <1>, after applying a charge when a corona discharge is generated by applying a voltage of 8 kV to a corona discharger arranged with an interval of 1 mm from the outer peripheral surface to charge the outer peripheral surface. Since the absolute value of the surface potential decay rate from 0.1 second to 0.2 second is set to 0.1 [V / sec] or more, it is possible to prevent the occurrence of uneven density and white image fog as much as possible. In addition, it is possible to reliably and stably obtain a high-quality image that can reliably maintain good image quality even during continuous printing or partial image printing, and can also cope with color images. Can do.

  According to the invention <2>, since at least one resin layer is made of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent, heat or hot air is used instead of ultraviolet irradiation or electron beam irradiation. Compared to forming by drying and curing with a large amount of equipment, it can save a lot of equipment and space for drying, and also suppress variations in film formation caused by difficult control of the drying process In addition, the resin layer can be formed with high accuracy.

  According to the invention <3>, since at least one resin layer is formed by applying a solvent-free coating solution and irradiating with ultraviolet rays or electron beams, the same effects as described above can be brought about.

  According to the invention <4>, since the elastic layer is disposed between the shaft member and the radially innermost resin layer, the resin layer is pressed against the latent image holding member or the stratified blade. The stress applied to the resin layer can be relieved, the durability of the resin layer can be improved, and the stress on the toner can also be relieved, thereby contributing to the formation of a stable image over a long period of time.

  According to the invention of <5>, the resin forming the shaft member is made of at least one kind of synthetic resin selected from the group consisting of general-purpose resin, general-purpose engineering plastic, and super-engineering plastic. Since it can be molded by a resin molding machine, it can be manufactured at low cost, the degree of freedom of the shape of the molded product can be increased, and the recyclability can be improved.

  According to the invention <6>, general-purpose engineering plastics or super engineering plastics are made of polyacetal, polyamide 6, polyamide 6, 6, polyamide 12, polyamide 4, 6, polyamide 6, 10, polyamide 6, 12, polyamide 11, polyamide. MXD6, polybutylene terephthalate, polyphenylene oxide, polyphenylene sulfide, polyphenylene ether, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone, polyethylene terephthalate, polyarylate polytetrafluoroethylene, or liquid crystal polymer Therefore, these materials can be obtained inexpensively and easily. Further, bending strength, it is less water changes, heat resistance and the like, which comprises the characteristics required for the developing roller, preferably.

  According to the invention of <7>, the conductive agent contained in the resin forming the shaft member is at least selected from the group consisting of carbon black, graphite, tin oxide, titanium oxide, zinc oxide, nickel, aluminum, and copper. Since it is a kind, it is possible to impart the required volume resistivity to the developing roller, and these materials are excellent in fluidity and bending strength, and are advantageous for forming a shaft member. .

  According to the invention <8>, the shaft member is made of a hollow cylindrical body, and the hollow cylindrical body is provided with reinforcing ribs extending radially inward from the outer peripheral surface thereof. The strength against bending received from the drum or the like can be increased, and as a result, the quality of the printed image can be improved.

  According to the invention of <9>, the shaft member is provided with a metal shaft that is disposed at the center in the radial direction of the hollow cylindrical body and passes through the hollow cylindrical body, and the metal shaft supports the radially inner end of the reinforcing rib. Since it comprised so, the intensity | strength with respect to the bending of a shaft member can be improved further.

  According to the invention of <10>, since the hollow cylindrical body is configured by connecting a plurality of cylindrical members in the length direction, the processing accuracy is improved by shortening the length of the member, and the ease of processing. The developing roller can be made with high accuracy and low cost.

  According to the invention <11>, since the developing roller according to any one of <1> to <10> is provided, it is possible to prevent density unevenness and white image fog as much as possible. In addition, it is possible to reliably maintain a good image quality even during continuous printing or partial image printing, and to reliably and stably obtain a high-quality image that can also cope with a color image. .

  The embodiment of the present invention will be described in more detail. FIG. 3A is a cross-sectional view showing the developing roller of the present embodiment, and FIG. 3B is a side view corresponding to the view taken along the line bb in FIG. The developing roller 1 is formed by forming a semiconductive elastic layer 3 on the outer periphery of the shaft member 2 and further forming a semiconductive resin layer 4 on the elastic layer 3. The elastic layer 3 is essential. Not a configuration. The shaft member 2 includes a solid cylindrical body 5 made of resin and respective shaft portions 6 formed at both ends thereof. These shaft portions 6 are not shown in the attached state and are supported by a roller of an electrophotographic apparatus in an attached state. It is pivotally supported by the part.

  Since the shaft member 2 is made of resin, the diameter of the shaft member 2 can be increased without causing a significant increase in weight as compared with the case where the shaft member 2 is made of metal or the like. Since it contains an agent, it has good electrical conductivity, whereby a desired potential can be applied to the surface of the developing roller 1.

  The resin material used for the shaft member 2 is not particularly limited as long as it has an appropriate strength and can be molded by injection molding or the like, and can be appropriately selected from general-purpose resins and engineering plastics. is not. Specifically, as an engineering plastic, for example, polyacetal, polyamide resin (for example, polyamide 6, polyamide 6 · 6, polyamide 12, polyamide 4 · 6, polyamide 6 · 10, polyamide 6 · 12, polyamide 11, polyamide MXD6) (Polyxylene diamine and adipic acid)), polybutylene terephthalate, polyphenylene oxide, polyphenylene ether, polyphenylene sulfide, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone , Polyethylene terephthalate, polyarylate, liquid crystal polymer, polytetrafluoroethylene, and the like. Examples of the general-purpose resin include polypropylene, acrylonitrile-butadiene-styrene (ABS) resin, polystyrene, and polyethylene. In addition, a melamine resin, a phenol resin, a silicone resin, etc. can also be used. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Among the above, engineering plastics are particularly preferable, and polyacetal, polyamide resin, polybutylene terephthalate, polyphenylene ether, polyphenylene sulfide, polycarbonate, and the like are preferable because they are thermoplastic and have excellent moldability and mechanical strength. . In particular, polyamide 6 · 6, polyamide MXD6, polyamide 6 · 12, or a mixed resin thereof is preferable. Although there is no problem in using a thermosetting resin, it is preferable to use a thermoplastic resin in consideration of recyclability.

  Various conductive agents can be used as long as they can be uniformly dispersed in the resin material, such as carbon black powder, graphite powder, carbon fiber, aluminum, copper, nickel, etc. A powdered conductive agent such as metal powder, metal oxide powder such as tin oxide, titanium oxide and zinc oxide, and conductive glass powder is preferably used. These may be used individually by 1 type and may be used in combination of 2 or more type. The blending amount of the conductive agent may be selected so as to obtain an appropriate resistance value according to the intended use and situation of the conductive roller, and is not particularly limited. Usually, the material of the shaft member 2 is used. It is preferable to set it as 5 to 40 weight% with respect to the whole, especially 5 to 20 weight%.

The volume resistivity of the shaft member 2 may be appropriately set according to the use of the roller as described above, but is usually 1 × 10 ⁰ to 1 × 10 ¹² Ω · cm, preferably 1 × 10 ² to. 1 × 10 ¹⁰ Ω · cm, more preferably 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω · cm.

  In the material of the shaft member 2, various conductive or non-conductive fibrous materials, whiskers, ferrites, and the like can be blended as needed for the purpose of reinforcement or increase in weight. Examples of the fibrous material include fibers such as carbon fiber and glass fiber, and examples of the whisker include inorganic whiskers such as potassium titanate. These may be used singly or in combination of two or more. These blending amounts can be appropriately selected according to the length and diameter of the fibrous material or whisker to be used, the type of the main resin material, the intended roller strength, etc. 70% by weight, in particular 10-20% by weight.

  Since the shaft member 2 constitutes the core of the developing roller 1, it needs to have sufficient strength to stably exhibit good performance as a roller, and usually has bending strength in accordance with JIS K 7171. It is preferable that it has a strength of 80 MPa or more, particularly 130 MPa or more, so that good performance can be reliably exhibited over a long period of time. In addition, although there is no restriction | limiting in particular about the upper limit of bending strength, Generally it is about 500 Mpa or less.

  The shaft member 2 shown in FIG. 3 is made of a solid cylindrical body 5, but instead of the shaft member 2, a shaft member 12 made of a hollow cylindrical body 13 can also be used, and FIG. 4 uses the shaft member 12. 2 is a cross-sectional view illustrating a developing roller 11. FIG. The developing roller 11 is the same as the developing roller 1 in that the elastic layer 3 and the resin layer 4 are formed on the outer side of the shaft member 12 in this order. The shaft member 12 is formed by bonding a hollow cylindrical body 13 and a cap member 12 by bonding or the like. The hollow cylindrical body 13 includes a cylindrical portion 13a, a bottom portion 13b, and a shaft portion 6, and the cap member 14 is a lid. It consists of a portion 14 a and a shaft portion 6. Both shaft portions 6 are pivotally supported by a roller support portion of an electrophotographic apparatus (not shown) in the attached state.

  By using a hollow shaft member 12 in place of the shaft member 2, the shaft member can be further reduced in weight. In particular, when the outer diameter of the developing roller exceeds 12 mm, a hollow structure is preferable. .

  FIG. 5 is a sectional view showing the developing roller 21 using the shaft member 22 in place of the shaft member 12, and FIG. 6 is a perspective view thereof. The shaft member 22 is formed by bonding the hollow cylindrical body 23 and the cap member 22 by bonding or the like. The hollow cylindrical body 23 includes a cylindrical portion 23a, a bottom portion 23b, a gear portion 7 and a shaft hole portion 8, while The cap member 24 includes a lid portion 24 a and a shaft portion 6, similarly to the developing roller 11.

  The shaft portion 6 and the shaft hole portion 8 are pivotally supported by a roller support portion (not shown) of the electrophotographic apparatus, and the rotational driving force of the developing roller is directly transmitted to the shaft member via the gear portion 7. Even in the hollow cylindrical body 23 having such a gear portion 7, since the shaft member 22 is made of resin, it can be integrally formed by injection molding or the like, and the shaft member 22 is made of metal. In this case, the cost of the shaft member can be reduced as compared with the case where the gear portion must be a separate member. The gear portion 7 can be integrally molded, whether it is a spur gear or a haze gear.

  Further, the thickness of the hollow cylindrical portion 13a or 23a is preferably thin in terms of weight reduction as long as the strength is sufficient, for example, 0.3 to 3 mm, more preferably It is good to set it as 1-2 mm.

  The method for forming the shaft members 2, 12, and 22 using the blended material composed of the resin material and the conductive agent is not particularly limited, and may be a known molding method depending on the type of the resin material. In general, an injection molding method using a mold is applied.

  FIG. 7 is a cross-sectional view showing the mold 30 for forming the hollow cylindrical body 23 in a closed state. The mold 30 includes a cylindrical mold 31, a core mold 32, and a runner mold 33. The mold 31 is configured to be opened and closed by being spaced apart from each other in the length direction of the cylindrical mold 31. In a state where the mold 30 is closed, resin is injected from the first sprue 36 through the runner 37 and the second sprue 34 into the cavity 35 formed by the cylindrical mold 31 and the core mold 32, and then the mold The hollow cylindrical body 23 can be formed by cooling and solidifying it in the inside 30. Further, by using the hot runner method, the material in the runner 37 can be used without waste.

  Here, since the cylindrical mold 31 and the core mold 32 have a structure that is not divided in the circumferential direction, the hollow cylindrical body 23 can be made uniform in the circumferential direction. Further, instead of using the core mold 32, an inert gas can be introduced, and the hollow portion can be formed by the pressure of this gas.

  FIG. 8 is a side view showing a shaft member having a different end structure. FIGS. 8A and 8B are examples in which both end portions are configured by the shaft portion 6, and FIG. , An example in which both end portions are configured by the shaft hole portion 8, and FIGS. 8D and 8E are examples in which one of both end portions is configured by the shaft portion 6 and the other is configured by the shaft hole portion 8. Show. Moreover, the example of FIG.8 (b)-FIG.8 (e) shows the example which provided the gear part 7 in one edge part. In addition, the gear part 7 can also be provided in the both sides of an edge part, and a shaft member bears the function which mediates power transmission in this case. In either case, the gear portion 7 can be formed integrally with the cylindrical portion or the column portion.

  Here, the structure shown in FIG. 8A corresponds to the shaft member 2 or 12, and the structure shown in FIG. 8D corresponds to the shaft member 22.

  Further, the shaft portions 6 of the shaft members 2 and 12 shown in FIG. 8 have the simplest cylindrical shape as shown in the perspective view of FIG. 9A. Instead of this, for example, FIG. The taper shown in FIG. 9B, the one subjected to D-cut processing shown in FIG. 9C, the prismatic one shown in FIG. 9D, and the pointed end shown in FIG. 9 (f), an annular groove shown in FIG. 9 (g), a stepped portion shown in FIG. 9 (g), and a spline or gear external tooth portion shown in FIG. 9 (h). Similarly, the shaft hole portion 8 has a D-shaped cross-sectional shape shown in FIG. 9 (j) in addition to the simple round hole shape shown in the perspective view of FIG. 9 (i). 9, an oval cross-sectional shape shown in FIG. 9 (k), a square hole shape shown in FIG. 9 (l), and a spline on the inner peripheral surface shown in FIG. 9 (m) Alternatively, a gear formed with an inner tooth portion for gears, a gear having a tapered hole portion shown in FIG. 9 (n), a round hole with a key groove shown in FIG. 9 (o), or the like can be used.

Furthermore, in place of the gear portion 7 shown in the perspective view of FIG. 9 (r), a stepped portion shown in FIG. 9 (p), a flange portion shown in FIG. 9 (q), or the like can be used.

  FIG. 14 is a perspective view showing a developing roller 51 using a shaft member 52 instead of the shaft member 12 shown in FIG. 4, and FIG. 15 is a perspective view showing the shaft member 52. The shaft member 52 includes a hollow cylindrical body 53 and a metal shaft 56. The hollow cylindrical body 53 is provided with reinforcing ribs 55 extending radially inward from the outer peripheral surface thereof. Is configured by connecting a plurality of cylindrical members 54 in the length direction thereof. As described above, the hollow cylindrical body 53 is composed of a plurality of cylindrical members 54, and the length of the members is shortened as compared to the case of a conventional metal pipe or a resin integrated molded product by dividing the hollow cylindrical body 53 in the length direction. Therefore, the processing accuracy can be improved, and the processing of individual members can be facilitated, thereby contributing to the improvement of productivity.

  At the center of the hollow cylinder 53 in the radial direction, a gold shaft 56 that passes through the hollow cylinder is arranged, and the gold shaft 56 is configured to support the radially inner ends of the reinforcing ribs 55, and this configuration causes the roller The strength of bending can be increased and the strength against bending can be increased.

  The connecting means between the cylindrical members 54 is not particularly limited. For example, a structure as shown in FIG. 16 can be exemplified, and the coupling can be achieved by fitting the end portions. . The cylindrical member 54 shown in the figure has a convex portion 62 and a rotation stop pin 63 on one end 61A side ((a) in the figure), and has a recess 65 and a rotation stop hole 66 on the other end 61B side. ((B) in the figure). (C) in the drawing is a cross-sectional view of the cylindrical member 54. The cylindrical members 54 having such a structure are fitted together while rotating with the end portions 61A and 61B facing each other, so that the convex portions 62 are the concave portions 65 and the rotation stop pins 63 are the rotation stop holes. 66 can be firmly coupled to each other. Since the roller is used by being rotated, it is preferable that the connecting means between the members includes a rotation preventing mechanism. In the cylindrical member 54 shown in the figure, the convex portion 62 and the concave portion 65 are tapered for centering.

  In the present invention, the shape of the shaft member 52 itself is not particularly limited, and can be appropriately set to a desired shape. For example, a gear portion 57 (see FIG. 17), a shaft portion having an appropriate shape such as a D-cut shape, or the like is formed on a member corresponding to the end portion in the longitudinal direction, or a member having only a gear portion is formed on the end after the roller body is formed. By joining to the portion, the end portions of the shaft member 52 in the longitudinal direction can have the shapes of these functional parts as desired. Accordingly, there is no need to use a shaft separately or to perform complicated machining on the shaft, and it is possible to obtain an advantage that it is easy to center a functional component.

  Further, the outer shape of the shaft member 52 is not limited to the cylindrical shape shown in FIG. 15 and the like, but may have a crown shape with a diameter increasing from both ends in the longitudinal direction toward the center as shown in FIG. it can. In the case of conventional metal pipes and resin-integrated products, the outer shape of the roller body is generally a straight cylindrical shape, and it is difficult to cope with a crown shape whose center is larger in diameter than both ends. Therefore, it is necessary to control the film thickness at the time of molding by expensive mold production, polishing of the elastic layer 3, coating of the resin layer 4 (dip etc.), and the like. In the present embodiment, by dividing the hollow cylindrical body 53 in the length direction, the processing difficulty of individual members is reduced, so that it is possible to easily cope with a crown shape and the like, and the processing accuracy Can be ensured well. In the present embodiment, the number of members forming the roller body is not particularly limited, and may be appropriately determined from the viewpoint of strength and cost.

  As a material for forming the hollow cylindrical body 53, the same material as described for the shaft member 2 can be used. Further, as the gold shaft 56, for example, sulfur free cutting steel, aluminum, stainless steel, or the like can be used. , Nickel, galvanized or the like can be used.

  The coupling between the hollow cylindrical body 53 and the metal shaft 56 may be usually performed by a conventional adhesive or the like, and is not particularly limited. For example, the hollow shaft 54 is passed through the metal shaft 56 while being heated in an oven or the like. Then, after cooling, the resin material of the hollow member 54 can be contracted and fixed to the metal shaft 56. Moreover, it is also preferable to provide a groove | channel, D cut, etc. in the metal shaft 56 as this connection means (not shown). The coupling means in this case is also preferably provided with an anti-rotation mechanism as in the case of the above-described member, so that the idle rotation of the metal shaft 56 during use can be prevented.

The developing roller 51 of the present embodiment can be manufactured by forming a shaft member 52 by connecting a plurality of cylindrical members 54 in the length direction and then providing the elastic layer 3 on the outer periphery thereof. Here, the procedure for forming the hollow cylindrical body 53 by the cylindrical member 54 according to the present embodiment is not particularly limited. For example, in the case of the cylindrical member 54 having a fitting structure as shown in FIG. Alternatively, the members can be directly coupled to form a hollow cylindrical body 53. If the member does not have a fitting structure, as shown in FIGS. A method may be used in which each cylindrical member 54 is sequentially inserted and then fixed to each other with an adhesive or the like to form a roller.

  Here, the resin layer 4 is composed of one layer or a plurality of layers, and at least one of them is preferably composed of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent.

  The resin layer 4 can give a required charge amount to the toner and obtain a required toner conveyance amount according to the specifications of the toner and the image forming apparatus, and also requires a toner supply amount to the latent image holding member. Characteristics such as electric resistance and surface properties are set so as to be the same.

  Examples of the ultraviolet curable resin or electron beam curable resin forming the resin layer 4 include polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, and alkyd resin. , Phenol resin, melamine resin, urea resin, silicone resin, polyvinyl butyral resin, and the like. These can be used alone or in combination. Furthermore, modified resins in which specific functional groups are introduced into these resins can also be used.

  Although it does not specifically limit as an ultraviolet curable resin or an electron beam curable resin, The (meth) acrylate type resin composition containing a (meth) acrylate oligomer is suitable.

  Examples of such (meth) acrylate oligomers include urethane (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, ether (meth) acrylate oligomers, ester (meth) acrylate oligomers, and polycarbonate (meth) acrylate oligomers. And fluorine-based and silicone-based acrylic oligomers.

  The (meth) acrylate oligomer is composed of a compound such as polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, adduct of polyhydric alcohol and ε-caprolactone, It can be synthesized by reaction with (meth) acrylic acid or by urethanizing a polyisocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  A urethane type (meth) acrylate oligomer is obtained by urethanizing a polyol, an isocyanate compound, and a (meth) acrylate compound having a hydroxyl group.

  Examples of the epoxy-based (meth) acrylate oligomer may be any reaction product of a compound having a glycidyl group and (meth) acrylic acid. Among them, a benzene ring, a naphthalene ring, a spiro ring, a dicyclopentadiene, A reaction product of a compound having a cyclic structure such as tricyclodecane and having a glycidyl group and (meth) acrylic acid is preferred.

  Furthermore, ether-based (meth) acrylate oligomers, ester-based (meth) acrylate oligomers and polycarbonate-based (meth) acrylate oligomers react with polyols (polyether polyols, polyester polyols and polycarbonate polyols) and (meth) acrylic acid, respectively. Can be obtained by:

  The resin composition for forming the resin layer 4 is blended with a reactive diluent having a polymerizable double bond for viscosity adjustment as necessary. As such a reactive diluent, for example, a monofunctional, difunctional or polyfunctional polymerizable compound having a structure in which (meth) acrylic acid is bonded to a compound containing an amino acid or a hydroxyl group by an esterification reaction or an amidation reaction Etc. can be used. These diluents are usually preferably used in an amount of 10 to 200 parts by weight per 100 parts by weight of the (meth) acrylate oligomer.

  As the conductive agent blended in the resin of the resin layer 4, an electronic conductive agent, an ionic conductive agent, or the like is used.

  Examples of the electronic conductive agent include conductive carbon such as ketjen black and acetylene black, rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, and a color treated with oxidation ( Ink) carbon, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium and other metals and metal oxides, polyaniline, polypyrrole, polyacetylene, etc. Conductive whiskers such as conductive polymer, carbon whisker, graphite whisker, titanium carbide whisker, conductive potassium titanate whisker, conductive barium titanate whisker, conductive titanium oxide whisker, and conductive zinc oxide whisker.

  The blending amount of these electronic conductive agents is preferably 100 parts by weight or less, for example, 1 to 100 parts by weight, particularly 1 to 80 parts by weight, especially 10 to 50 parts by weight, based on 100 parts by weight of the resin.

  However, when the carbon-based conductive agent is contained in the ultraviolet curable resin, it is preferably 20 parts by weight or less, particularly 10 parts by weight or less, especially 5 parts by weight or less based on 100 parts by weight of the resin. Since the carbon-based conductive agent easily absorbs ultraviolet rays when the amount exceeds the upper limit, the larger the amount of the conductive agent, the more difficult it is for the ultraviolet rays to reach the back of the layer, so that the progress of the ultraviolet curing reaction may not proceed sufficiently. is there.

  Examples of ionic conductive agents include perchlorate, chlorate, hydrochloride, bromine such as tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, and modified fatty acid dimethylethylammonium. Ammonium salts such as acid salts, iodates, borofluoride salts, sulfates, ethyl sulfates, carboxylates, sulfonates; alkali metals such as lithium, sodium, potassium, calcium, magnesium, alkaline earths Examples include metal perchlorates, chlorates, hydrochlorides, bromates, iodates, borofluorides, sulfates, trifluoromethyl sulfates, sulfonates, and the like. These ionic conductive agents are preferably used in an amount of 0.01 to 10 parts by weight, particularly 0.05 to 5 parts by weight, based on 100 parts by weight of the resin.

  In addition, the said electrically conductive agent may be used individually by 1 type, or may be used in combination of 2 or more types, In this case, it is also possible to combine an electronic conductive agent and an ionic conductive agent.

  In addition, when the conductive agent is a transparent conductive agent such as tin oxide, titanium oxide, zinc oxide, potassium titanate, barium titanate, nickel, copper, and other metal and metal oxides, ultraviolet rays are easily transmitted and ultraviolet curing is achieved. The effect of not hindering the polymerization of the mold resin is obtained. The blending amount of the transparent conductive agent is preferably 100 parts by weight or less, particularly 1 to 80 parts by weight, particularly 10 to 50 parts by weight with respect to 100 parts by weight of the resin.

  When the resin constituting the resin layer 4 is an ultraviolet curable resin, it is preferable to contain a polymerization initiator. As the ultraviolet polymerization initiator, known ones can be used. For example, 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal, alkoxy Benzophenone derivatives such as acetophenone, benzyldimethyl ketal, benzophenone and 3,3-dimethyl-4-methoxybenzophenone, 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, alkyl benzoylbenzoate, bis (4-dialkylaminophenyl) Benzene derivatives such as ketones, benzyl and benzylmethyl ketal, benzoin derivatives such as benzoin and benzoin isobutyl ether, benzoin isopropyl ether, 2-hydroxy-2-methyl Lupropiophenone, 1-hydroxycyclohexyl phenyl ketone, xanthone, thioxanthone and thioxanthone derivatives, fluorene, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl Pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1,2-benzyl-2-dimethylamino Such as -1- (morpholinophenyl) -butanone-1 and the like may be used alone or in combination of two or more.

  The blending amount of the ultraviolet polymerization initiator is preferably 0.1 to 10 parts by weight per 100 parts by weight of the (meth) acrylate oligomer.

  In the present invention, in addition to the above essential components, a tertiary amine such as triethylamine and triethanolamine, and an alkyl phosphine such as triphenylphosphine, if necessary, in order to promote the photopolymerization reaction by the photopolymerization initiator. A photopolymerization accelerator, a thioether photopolymerization accelerator such as p-thiodiglycol, and the like may be added. The amount of these compounds added is usually preferably in the range of 0.01 to 10 parts by weight per 100 parts by weight of the (meth) acrylate oligomer.

  For at least the outermost resin layer, it is preferable that the resin constituting the layer contains one or both of fluorine and silicon, thereby reducing the surface energy of the outermost resin layer. As a result, the frictional resistance of the developing roller can be reduced, the toner releasability can be improved, wear during long-term use can be reduced, and durability can be improved.

  As a raw material for forming an ultraviolet curable resin containing fluorine, it is preferable to contain a fluorine-containing compound having a polymerizable carbon-carbon double bond, and the fluorine-containing compound having a polymerizable carbon-carbon double bond. Or a composition comprising a blend of a fluorine-containing compound having a polymerizable carbon-carbon double bond and another type of polymerizable compound having a carbon-carbon double bond. Good.

  As the fluorine-containing compound having a polymerizable double bond between carbon atoms, fluoroolefins and fluoro (meth) acrylates are suitable.

As fluoroolefins, those having 2 to 12 carbon atoms in which 1 to all hydrogen atoms are substituted with fluorine are preferable. Specifically, hexafluoropropene [CF ₃ CF═CF ₂ , fluorine content 76 % By weight], (perfluorobutyl) ethylene [F (CF ₂ ) ₄ CH═CH ₂ , fluorine content 69 wt%], (perfluorohexyl) ethylene [F (CF ₂ ) ₆ CH═CH ₂ , fluorine containing 71% by weight], (perfluorooctyl) ethylene [F (CF ₂ ) ₈ CH═CH ₂ , fluorine content 72% by weight], (perfluorodecyl) ethylene [F (CF ₂ ) ₁₀ CH═CH ₂ , fluorine content 73% by weight], chlorotrifluoroethylene _[CF 2 = CFCl, fluorine content 49 wt%, 1-methoxy - (perfluoro-2 Chill-1-propene _{[(CF 3) 2 C =} CFOCH 3, fluorine content 63 wt%, 1,4-vinyl octafluorobutane _{[(CF 2) 4 (CH} = CH 2) 2, fluorine content 60 % By weight], 1,6-divinyldodecafluorohexane [(CF ₂ ) ₆ (CH═CH ₂ ) ₂ , fluorine content 64% by weight], 1,8-divinylhexadecafluorooctane [(CF ₂ ) ₈ ( CH = CH ₂ ) ₂ , fluorine content 67 wt%].

As the fluoro (meth) acrylate, a fluoroalkyl (meth) acrylate having 5 to 16 carbon atoms in which 1 to all hydrogen atoms are substituted with fluorine is preferable. Fluoroethyl acrylate (CF ₃ CH ₂ OCOCH═CH ₂ , fluorine content 34 wt%), 2,2,3,3,3-pentafluoropropyl acrylate (CF ₃ CF ₂ CH ₂ OCOCH═CH ₂ , fluorine content 44 _{wt%), F (CF 2)} 4CH 2 CH 2 OCOCH = CH 2 ( fluorine content 51 wt%), 2,2,2-trifluoroethyl acrylate _{[CF 3 CH 2 OCOCH = CH} 2, the fluorine content 37 wt%], 2,2,3,3,3-pentafluoropropyl acrylate [CF ₃ CF ₂ CH ₂ OCOCH = CH ₂ , fluorine content 47 wt%], 2- (perfluorobutyl) ethyl acrylate [F (CF ₂ ) ₄ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 54 wt%], 3- (perfluorobutyl ) -2-hydroxypropyl acrylate [F (CF ₂ ) ₄ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ , fluorine content 49 wt%], 2- (perfluorohexyl) ethyl acrylate [F (CF ₂ ) ₆ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 59 wt%], 3- (perfluorohexyl) -2-hydroxypropyl acrylate [F (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ , Fluorine content 55 wt%], 2- (perfluorooctyl) ethyl acrylate [F (CF ₂ ) ₈ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 62 wt%], 3- (perfluorooctyl) -2-hydroxypropyl acrylate [F (CF ₂ ) ₈ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ , fluorine Content 59 wt%], 2- (perfluorodecyl) ethyl acrylate [F (CF ₂ ) ₁₀ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 65 wt%], 2- (perfluoro-3-methylbutyl) Ethyl acrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₂ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 57 wt%], 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate [(CF _{3) 2 CF (CF 2)} 2 CH 2 CH (OH) CH 2 OCOCH = CH 2, the fluorine content 5 Wt%], 2- (perfluoro-5-methylhexyl) ethyl acrylate _{[(CF 3) 2 CF (} CF 2) 4 CH 2 CH 2 OCOCH = CH 2, fluorine content 61 wt%], 3- (par Fluoro-5-methylhexyl) -2-hydroxypropyl acrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₄ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ , fluorine content 57 wt%], 2- (par Fluoro-7-methyloctyl) ethyl acrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₆ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 64 wt], 3- (perfluoro-7-methyloctyl) -2 -Hydroxypropyl acrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOCH = CH ₂ , Nitrogen content 60 wt%], 1H, 1H, 3H-tetrafluoropropyl acrylate [H (CF ₂ ) ₂ CH ₂ OCOCH═CH ₂ , fluorine content 41 wt%], 1H, 1H, 5H-octafluoropentyl Acrylate [H (CF ₂ ) ₄ CH ₂ OCOCH═CH ₂ , fluorine content 53 wt%], 1H, 1H, 7H-dodecafluoroheptyl acrylate [H (CF ₂ ) ₆ CH ₂ OCOC (CH ₃ ) = CH ₂ , Fluorine content 59 wt%], 1H, 1H, 9H-hexadecafluorononyl acrylate [H (CF ₂ ) ₈ CH ₂ OCOCH═CH ₂ , fluorine content 63 wt%], 1H-1- (trifluoromethyl ) Trifluoroethyl acrylate [(CF ₃ ) ₂ CHOCOCH═CH ₂ , fluorine content 51 wt%], 1H, 1H, 3H-hexafluorobutyl acrylate [CF ₃ CHFCF ₂ CH ₂ OCOCH═CH ₂ , fluorine content 48 wt%], 2,2,2-trifluoroethyl methacrylate [CF ₃ CH ₂ OCOC (CH ₃ ) = CH _2, fluorine content 34 wt%], 2,2,3,3,3-pentafluoro-propyl methacrylate _{[CF 3 CF 2 CH 2 OCOC} (CH 3) = CH 2, fluorine content 44 wt%, 2- (perfluorobutyl) ethyl methacrylate [F (CF ₂ ) ₄ CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 51 wt%], 3- (perfluorobutyl) -2-hydroxypropyl methacrylate _{[F (CF 2) 4 CH} 2 CH (OH) CH 2 OCOC (CH 3) = CH 2, fluorine-containing Rate 47% by weight], 2- (perfluorohexyl) ethyl methacrylate _{[F (CF 2) 6 CH} 2 CH 2 OCOC (CH 3) = CH 2, fluorine content 57 wt%], 3- (perfluorohexyl) 2-hydroxypropyl methacrylate [F (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 53 wt%], 2- (perfluorooctyl) ethyl methacrylate [F ( _{CF 2) 8 CH 2 CH 2} OCOC (CH 3) = CH 2, fluorine content 61 wt%, 3-perfluorooctyl-2-hydroxypropyl methacrylate _{[F (CF 2) 8 CH} 2 CH (OH) CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 57 wt%], 2- (perfluorodecyl) ethyl methacrylate [F (CF ₂ ) ₁₀ CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 63 wt%], 2- (perfluoro-3-methylbutyl) ethyl methacrylate [(CF ₃ ) ₂ CF ( _{CF 2) 2 CH 2 CH 2} OCOC (CH 3) = CH 2, fluorine content 55 wt%], 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl methacrylate _{[(CF 3) 2 CF (} CF ₂ ) ₂ CH ₂ CH (OH) CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 51 wt%], 2- (perfluoro-5-methylhexyl) ethyl methacrylate [(CF ₃ ) ₂ CF (CF _{2) 4 CH 2 CH 2 OCOC} (CH 3) = CH 2, fluorine content 59 wt%], 3- (perfluoro-5-methylhexyl) -2 Hydroxypropyl methacrylate _{[(CF 3) 2 CF (} CF 2) 4 CH 2 CH (OH) CH 2 OCOC (CH 3) = CH 2, fluorine content 56 wt%], 2- (perfluoro-7-methyl-octyl ) Ethyl methacrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₆ CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 62 wt%], 3- (perfluoro-7-methyloctyl) -2- Hydroxypropyl methacrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 59 wt%], 1H, 1H, 3H-tetrafluoropropyl methacrylate _{[H (CF 2) 2 CH} 2 OCOC (CH 3) = CH 2, fluorine content 51 wt%], 1H, 1H, 5 - octafluoro pentyl methacrylate _{[H (CF 2) 4 CH} 2 OCOC (CH 3) = CH 2, fluorine content 51 wt%], 1H, 1H, 7H- dodecafluoroheptyl methacrylate _{[H (CF 2) 6 CH} 2 OCOC (CH ₃ ) = CH ₂ , fluorine content 57 wt%], 1H, 1H, 9H-hexadecafluorononyl methacrylate [H (CF ₂ ) ₈ CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 61 % By weight], 1H-1- (trifluoromethyl) trifluoroethyl methacrylate [(CF ₃ ) ₂ CHOCOC (CH ₃ ) = CH ₂ , fluorine content 48% by weight], 1H, 1H, 3H-hexafluorobutyl methacrylate _{[CF 3 CHFCF 2 CH 2 OCOC} (CH 3) = CH 2, the fluorine content 4 Wt%] and the like are exemplified.

  The fluorine-containing compound having a polymerizable double bond between carbon atoms is preferably a monomer, an oligomer, or a mixture of a monomer and an oligomer. As an oligomer, a 2-20 mer is preferable.

  The compound having another polymerizable double bond between carbon atoms that may be blended with the fluorine-containing compound having a double bond between carbon atoms is not particularly limited. ) Acrylate monomers or oligomers or mixtures of monomers and oligomers are preferred.

  Examples of the (meth) acrylate monomer or oligomer include, for example, urethane (meth) acrylate, epoxy (meth) acrylate, ether (meth) acrylate, ester (meth) acrylate, and polycarbonate (meth) acrylate. Or an oligomer, the monomer or oligomer of a silicone type (meth) acryl, etc. can be mentioned.

  The (meth) acrylate oligomer is composed of a compound such as polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, adduct of polyhydric alcohol and ε-caprolactone, It can be synthesized by reaction with (meth) acrylic acid or by urethanizing a polyisocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  A urethane type (meth) acrylate oligomer is obtained by urethanizing a polyol, an isocyanate compound, and a (meth) acrylate compound having a hydroxyl group.

  Examples of the epoxy-based (meth) acrylate oligomer may be any reaction product of a compound having a glycidyl group and (meth) acrylic acid. Among them, a benzene ring, a naphthalene ring, a spiro ring, a dicyclopentadiene, A reaction product of a compound having a cyclic structure such as tricyclodecane and having a glycidyl group and (meth) acrylic acid is preferred.

  Furthermore, ether-based (meth) acrylate oligomers, ester-based (meth) acrylate oligomers and polycarbonate-based (meth) acrylate oligomers react with polyols (polyether polyols, polyester polyols and polycarbonate polyols) and (meth) acrylic acid, respectively. Can be obtained by:

  The raw material for forming the ultraviolet curable resin containing silicon preferably contains a silicon-containing compound having a polymerizable carbon-carbon double bond, and silicon having a polymerizable carbon-carbon double bond. The composition may be composed of only a contained compound, and is composed of a composition obtained by blending a silicon-containing compound having a polymerizable carbon-carbon double bond and another kind of polymerizable compound having a carbon-carbon double bond. May be.

  As the silicon-containing compound having a polymerizable double bond between carbon atoms, both-end-reactive silicone oils, one-end-reactive silicone oils, and (meth) acryloxyalkylsilanes are suitable. As the reactive silicone oil, those having a (meth) acryl group introduced at the terminal are preferable.

  Specific examples of the silicon-containing compound suitable for the present invention are shown below.

  One of these silicon-containing compounds may be used alone, or two or more thereof may be mixed and used, or another compound having a carbon-carbon double bond that does not contain silicon may be used.

  These silicon-containing compounds having a polymerizable carbon-carbon double bond and other compounds having no carbon-containing carbon-carbon double bond are preferably used as a monomer, an oligomer, or a mixture of a monomer and an oligomer.

  The other compound having a polymerizable double bond between carbon atoms that may be blended with the silicon-containing compound having a polymerizable double bond between carbon atoms is not particularly limited. ) Acrylate monomers or oligomers or mixtures of monomers and oligomers are preferred. As an oligomer, a 2-20 mer is preferable.

  Examples of the (meth) acrylate monomer or oligomer include urethane (meth) acrylate, epoxy (meth) acrylate, ether (meth) acrylate, ester (meth) acrylate, polycarbonate (meth) acrylate, and the like. And fluorine-based (meth) acrylic monomers or oligomers.

  The (meth) acrylate oligomer is composed of a compound such as polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, adduct of polyhydric alcohol and ε-caprolactone, It can be synthesized by reaction with (meth) acrylic acid or by urethanizing a polyisocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  A urethane type (meth) acrylate oligomer is obtained by urethanizing a polyol, an isocyanate compound, and a (meth) acrylate compound having a hydroxyl group.

  Examples of the epoxy-based (meth) acrylate oligomer may be any reaction product of a compound having a glycidyl group and (meth) acrylic acid. Among them, a benzene ring, a naphthalene ring, a spiro ring, a dicyclopentadiene, A reaction product of a compound having a cyclic structure such as tricyclodecane and having a glycidyl group and (meth) acrylic acid is preferred.

  Furthermore, ether-based (meth) acrylate oligomers, ester-based (meth) acrylate oligomers and polycarbonate-based (meth) acrylate oligomers react with polyols (polyether polyols, polyester polyols and polycarbonate polyols) and (meth) acrylic acid, respectively. Can be obtained by:

  In addition, an appropriate amount of various additives can be added to the ultraviolet curable resin constituting the resin layer 4 as necessary.

  Further, it is preferable to disperse fine particles in the resin layer 4, thereby forming minute irregularities on the surface of the resin layer 4 to ensure the conveying force of the toner carried on the outer peripheral surface to the latent image holding member. Can be a thing.

  The fine particles are preferably rubber or synthetic resin fine particles or carbon fine particles. Specifically, silicone rubber, acrylic resin, styrene resin, acrylic / styrene copolymer, fluorine resin, urethane elastomer, urethane acrylate, melamine resin. One type or two or more types of phenol resins are preferred.

  The addition amount of the fine particles is preferably 0.1 to 100 parts by weight, particularly 5 to 80 parts by weight with respect to 100 parts by weight of the resin.

  The average particle diameter a of the fine particles is preferably 1 to 50 μm, particularly 3 to 20 μm. The thickness b of the resin layer in which fine particles are dispersed is preferably 1 to 50 μm, and the ratio a / b between the average particle diameter a (μm) of the fine particles and the thickness b (μm) is It is preferable to set it as 1.0-5.0, and an appropriate micro unevenness | corrugation can be formed in the surface of the resin layer 4 by making a / b ratio into this range.

  As a method of forming the resin layer 4 made of an ultraviolet curable resin or an electron beam curable resin, a coating liquid made of a composition containing the resin component and the conductive agent and other additives is applied to the surface. A method of irradiating with ultraviolet rays or electron beams is preferably employed. The coating liquid preferably contains no solvent, or a solvent having high volatility even at room temperature may be used as the solvent.

  As a method for applying the coating liquid, a dipping method in which a developing roller having no resin layer in the resin liquid is dipped in a dipping solution, a spray coating method, a roll coating method, or the like is appropriately selected according to the situation. be able to.

  The thickness of the resin layer 4 is not particularly limited, but is usually 1 to 500 μm, particularly 3 to 200 μm, and particularly preferably about 5 to 100 μm. If the thickness is less than 1 μm, the charging performance of the surface layer may not be sufficiently secured due to friction during long-term use. On the other hand, if the thickness exceeds 500 μm, the developing roller surface becomes hard and damages the toner. In some cases, the toner adheres to a latent image holding member such as a photosensitive member or a stratified blade, resulting in an image defect.

  Next, the elastic layer 3 will be described. Although the elastic layer 3 is not an essential component, the stress applied to the resin layer 4 when the resin layer 4 is pressed against the latent image holding member or the layered blade can be relieved, and the durability of the resin layer is improved. For this purpose, it is preferable to provide a semiconductive elastic layer 3. As the elastic layer 3, an elastic body provided with conductivity by adding a conductive agent to an elastomer alone or a foam body obtained by foaming it is used. It is done. The elastomer that can be used here is not particularly limited, and nitrile rubber, ethylene-propylene rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, urethane rubber, acrylic rubber, chloroprene rubber, butyl rubber, An epichlorohydrin rubber etc. are illustrated and these can be used individually or in combination of 2 or more types. Of these, ethylene-propylene rubber, butadiene rubber, silicone rubber, and urethane rubber are preferably used in the present invention. A mixture of these and other rubber materials is also preferably used. In particular, in the present invention, a resin having a urethane bond is preferably used.

  Moreover, these elastomers can be used as foam bodies that are chemically foamed using a foaming agent, or foamed by mechanically entraining air like polyurethane foam. In the present invention, a so-called RIM molding method may be used in a molding process for integrating the shaft member 2 and the elastic layer 3. That is, two types of monomer components constituting the raw material component of the elastic layer 3 are mixed and injected into a cylindrical mold and polymerized to integrate the shaft member 2 and the elastic layer 3. As a result, the molding process can be performed in about 60 seconds from the injection of the raw material to the demolding, so that the production cost can be greatly reduced.

  As the conductive agent added to the elastic layer 3, the same conductive agent blended in the resin constituting the resin layer 4 can be used.

In the present invention, the volume resistivity of the semiconductive elastic layer is adjusted to 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm, preferably 1 × 10 ⁴ to 1 × 10 ⁸ Ω · cm. If the resistance value is less than 10 ³ Ωcm, the charge may leak to the latent image holder or the developing roller may be destroyed by the voltage. On the other hand, if the resistance value exceeds 10 ¹⁰ Ωcm, a sufficient developing bias is obtained. It is difficult to cover the ground.

  Since the developing roller 1 is used in contact with a latent image holding member, a stratified blade, etc., the elastic layer 3 preferably has a small compression set, specifically, 20% or less, more specifically 10% or less. Preferably there is. Use of polyurethane rubber as the rubber material is preferable because the compression set can be designed to be small.

  A cross-linking agent and a vulcanizing agent can be added to the semiconductive elastic layer 3 as necessary to make the elastomer into a rubbery material. In this case, a vulcanization aid, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanization retarder, etc. can be used in any case of organic peroxide crosslinking and sulfur crosslinking. In addition to the above, peptizers, foaming agents, plasticizers, softeners, tackifiers, tackifiers, separating agents, mold release agents, extenders, and coloring agents commonly used as rubber compounding agents. Etc. can be added.

  The hardness of the elastic layer 3 is not particularly limited, but it is preferably 80 degrees or less, particularly 30 to 70 degrees in terms of Asker C hardness. In this case, if the hardness exceeds 80 degrees, the original function of the elastic layer, which relieves stress applied to the developing roller and toner, cannot be expressed, and for example, the contact area between the developing roller and the latent image holder is small. Therefore, there is a possibility that good development cannot be performed. Further, the toner is damaged, and the toner adheres to the photosensitive member or the layered blade. On the other hand, if the hardness is too low, the frictional force with the photoconductor and the layered blade increases, which may cause image defects such as jitter.

  Since the elastic layer 3 is used in contact with a photoreceptor or a layered blade, even when the hardness is set to a low hardness, it is preferable to make the compression set as small as possible, specifically 20% or less. It is preferable.

  In the present invention, the surface roughness of the elastic layer 3 is preferably 1 to 20 [mu] mRz, more preferably 1.5 to 18 [mu] mRz in terms of JIS 10-point average roughness. When the average roughness exceeds 20 μm Rz, it is necessary to form a thick coating layer of the developing roller, so that the surface of the developing roller becomes hard. As a result, the toner is damaged and the toner adheres to the latent image holding member or the stratified blade. May occur and cause image defects.

  On the other hand, when the average roughness is less than 1 μm Rz, when the coating layer is formed, the average roughness of the surface of the developing roller becomes too small, and the toner carrying amount decreases, so that the image density may be lowered. In the present invention, the surface roughness is measured using a surface roughness meter “Surfcom 590A” (manufactured by Tokyo Seimitsu Co., Ltd.) in a measurement length of 2.4 mm in a direction orthogonal to the axial direction and a measurement speed of 0.8. This is a value obtained by measuring 300 or more locations at 3 mm / sec and a cutoff wavelength of 0.8 mm so that there is no deviation in the length direction and circumferential direction of the roller.

The developing roller 1 of the present invention is not particularly limited, but the electrical resistance value when 100 V is applied is preferably 10 ⁴ to 10 ¹⁰ Ω, particularly 10 ⁵ to 10 ⁹ Ω. If this resistance value is less than 10 ⁴ Ω, gradation control may be extremely difficult, and if there is a defect in the photosensitive drum such as a photosensitive member, bias leakage may occur. On the other hand, if the resistance value exceeds 10 ¹⁰ Ω, for example, when developing toner on a latent image holding member such as a photoconductor, the developing bias causes a voltage drop due to the high resistance of the developing roller itself, which is sufficient for development. In some cases, the development bias cannot be secured, and a sufficient image density cannot be obtained. The resistance value can be measured by, for example, pressing the developing roller against a flat plate or cylindrical counter electrode with a predetermined pressure, applying a voltage of 100 V between the shaft member and the counter electrode, and obtaining the current value at that time. it can.

  As described above, it is important to control the resistance value of the developing roller appropriately and uniformly from the viewpoint of maintaining the electric field strength for moving the toner appropriately and uniformly. It is important for the toner charge amount to be optimized and uniform that the charge retention ability of the toner is controlled and kept uniform, and further that the surface residual potential is attenuated at a constant rate. In this case, the surface charge retention capability is usually examined by measuring the surface resistance by placing a pair of electrodes on the surface of the developing roller and applying a constant voltage between the two electrodes, but in this case the current is only on the surface. Therefore, the surface of the developing roller does not flow, but the developing roller surface cannot be accurately evaluated.

  Although improvement of accuracy by the four-terminal method has been proposed, especially in the case of a multi-layer developing roller, the surface layer is quite thin, and it is difficult to characterize only the surface even in this method. . Therefore, the characteristic values obtained by these conventional measuring methods cannot accurately represent the surface charge holding ability.

  Therefore, in the present invention, in a measurement environment of 22 ° C. and 50% RH, a voltage of 8 kV is applied to a corona discharger disposed at a distance of 1 mm from the surface of the developing roller to generate a corona discharge to charge the surface. In this case, the surface charge retention ability is evaluated based on the absolute value of the surface potential decay rate from 0.1 second to 0.2 second after the charge application, and the absolute value of the surface potential decay rate is set to 0.1 [V / Sec] or more.

  In this case, if the surface potential decay rate value is less than 0.1 [V / sec], surface charge gradually accumulates during continuous operation, and the toner charge amount on the developing roller exceeds a predetermined value, For example, when the image is formed by the development process, the effective development bias exceeds the white background potential of the photosensitive member, thereby causing high voltage fog to the white background printing portion. In some cases, an electric field generated by toner charging exceeds a maximum value, and a discharge is generated between the latent image holding member such as a photosensitive member and an image defect may occur. The polarity charged by corona discharge may be either positive or negative. In the present invention, the surface potential decay rate value by corona charging may be 0.1 [V / sec] or more. More preferably, the surface potential decay rate value is 0.15 to 10 [V / sec].

  Hereinafter, the attenuation of the potential on the surface of the developing roller will be briefly described.

  Usually, when the charge decay curve plots the time t [sec] versus the logarithm logV of the surface potential, a linear relationship is derived, and the relaxation time (time constant) can be set from the slope of this straight line. However, the attenuation curve in the actual developing roller cannot obtain a linear relationship as shown in FIG. This is considered due to the fact that the decay time constant shows the voltage dependence of the residual surface potential. Here, for example, the rotational peripheral speed of the developing roller is about 0.4 sec / 1 rotation in many cases, and it is considered that the charge decay speed in this extremely short time is an important characteristic, and after passing through the stratified blade. The time from scraping to scraping by the toner application roller is about 0.2 sec. Therefore, the surface potential decay rate from 0.2 sec after the surface is charged becomes a particularly important characteristic.

  In the present invention, non-contact corona charging is used as means for applying a predetermined charge to the surface of the developing roller. In this charging method, it is difficult to identify the initial charging potential V = 0. Therefore, in actual measurement, the decay rate [V / sec] of the surface potential from 0.1 seconds to 0.2 seconds later is measured, and this decay rate is controlled. As a method of calculating the decay rate, the surface potential value after 0.1 seconds is set as an initial value, and the surface potential value after 0.2 seconds is linearly approximated by the least square method, and the surface potential is calculated from the slope. A method for obtaining the potential decay rate can be employed.

  The application of charge to the developing roller and the measurement of the surface potential can be performed by, for example, the apparatus shown in FIG. That is, both ends of the shaft member 2 of the developing roller 1 are held by the chuck 41 to support the developing roller 1, and a small corotron discharger (corona discharger) 42 and a surface potential meter 43 are illustrated in FIG. Thus, the measurement unit 44 arranged in parallel at a predetermined interval is disposed opposite the surface of the developing roller 1 with a gap of 1 mm, and the measuring unit 44 is moved to the developing roller 1 while the developing roller 1 is kept stationary. A method of measuring the surface potential while applying a surface charge by moving at a constant speed from one end to the other end in the length direction is suitably employed.

  In order to realize a developing roller having a surface potential decay rate value of 0.1 [V / sec] or more, the surface potential decay rate value of the resin layer formed as described above is 0.1 [V / sec] or more. It is preferable. Even if the surface potential decay rate value is less than 0.1 [V / sec], the surface potential decay rate value is reduced to 0.1 [V by reducing the thickness of the resin layer to 3 to 10 μm, for example. / Sec] or more can be realized.

  The developing roller 1 of the present invention can be incorporated in an image forming apparatus using toner. Specifically, as shown in FIG. 1, a toner supplying roller 94 for supplying toner and an electrostatic latent image are held. A developing roller 91 is disposed between the photosensitive drum 95 (latent image holding member) 95 with a small gap 92 with respect to the photosensitive drum 95, and the developing roller 91, the photosensitive drum 95, and the toner supply roller 94. The toner 96 is supplied to the surface of the developing roller 91 by the toner supply roller 94 by applying a predetermined voltage between the photosensitive drum 95 and the developing roller 91. A uniform thin layer can be prepared by the blade 97, and the toner 96 formed in the thin layer can fly over the gap 92 to the photosensitive drum 95 to visualize the latent image. Note that the details of FIG. 1 have been described in the background art, and will not be described.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to these.

  When the developing roller does not have an elastic layer, a resin layer is formed directly on the shaft member made of an aluminum pipe, or when the developing roller has an elastic layer, an elastic layer is formed on the shaft member. A rear resin layer is formed, and a developing roller having the structure shown in FIG. 3 is produced. Examples 1 to 10 are used. For comparison with the developing roller of the example, only the shaft member having no resin layer is used. A developing roller having a part of the configuration different from that of the present invention including the developing roller is prepared as Comparative Examples 1 to 3. Then, for the developing rollers of these examples and comparative examples, measurement and evaluation of roller characteristics and image evaluation were performed. The specifications of each developing roller and the results of these evaluations are shown in Tables 6-8.

In forming each resin layer, the materials shown in Table 6 were blended in parts by weight shown in “Formulation (parts by weight)” in Tables 7 and 8, and the shaft member was placed in a solution in which the blended resin material was dissolved. Immersion coating (dip method) or a coating made of the compounded resin material was applied with a roll coater (coater method), and then this was heat-cured (heated or air-dried), UV-cured, or electron-beam cured. .
Regarding the preparation of each sample, whether the resin was applied by the dip method or the coater method, and whether the curing process was performed by heat curing (heating or air drying), ultraviolet curing, or electron beam curing Are listed in the corresponding columns of Tables 7 and 8.
In order to cure the resin layer with ultraviolet rays, the UV light is irradiated at an illuminance of 400 mW and an integrated light quantity of 1000 mJ / cm ² using a UNICURE UVH-0252C apparatus manufactured by USHIO ELECTRIC CO., LTD. While rotating the developing roller coated with the resin layer. Was irradiated. Further, when the resin is cured by an electron beam, a rotating voltage is rotated using a Min-EB apparatus manufactured by Ushio Electric Co., Ltd. Electron beam irradiation was performed under the condition of irradiation time of 1 minute.

  The presence / absence of the elastic layer and the material of the elastic layer when the elastic layer is formed are described in the column “Presence / absence / type of elastic layer”.

  When the elastic layer is made of urethane, propylene oxide and ethylene oxide are added to glycerin to give a molecular weight of 5000 to 100 parts by weight of a polyether polyol (OH value 33), and 1,4-butanediol. Add 0 parts by weight, 1.5 parts by weight of silicone surfactant, 0.5 parts by weight of nickel acetylacetonate, 0.01 parts by weight of dibutyltin dilaurate and 0.01 parts by weight of sodium perchlorate and mix with a mixer. Thus, a polyol composition was prepared. After the polyol composition was stirred and degassed under reduced pressure, 17.5 parts by weight of urethane-modified MDI was added and stirred for 2 minutes, and then the shaft member was placed in and heated to 110 ° C. It was cast into a mold or a container and cured for 2 hours, and the outer periphery was polished to form an elastic layer having an outer diameter of 12 mm, an elastic layer thickness of 500 μm, and a total length of 210 mm.

  When the elastic layer is made of silicone, liquid silicone rubber is injected into the cavity of the mold in which the shaft member is inserted, and is cooled and cured in the mold. An elastic layer having a layer portion thickness of 300 μm and a total length of 210 mm was formed.

  The toner charge amount and toner transport amount in Tables 7 and 8 were determined as follows. That is, a cartridge equipped with a developing roller is incorporated into the image forming apparatus, the developing roller is idled without printing, the cartridge is taken out, and the toner charge amount is measured by taking the toner on the surface of the developing roller into the Faraday gauge. Further, when the toner charge amount is measured as described above, the weight of the removed toner is measured, and the area of the developing roller surface portion from which the toner has been removed is calculated, whereby the toner weight per unit area is calculated. The obtained toner transport amount was used.

  The image evaluation was performed as follows. That is, the development roller of each example and comparative example is mounted on a commercially available printer having a nonmagnetic jumping development unit portion shown in FIG. 1, and a development bias voltage in which alternating current is superimposed on direct current is applied, Reverse jumping development was performed using a negatively charged nonmagnetic one-component toner having an average particle diameter of 7 μm. “Initial” image evaluation is performed by printing a black image, a full white image, a halftone image, and a pattern image immediately after mounting the developing roller, and visually determining the print image quality for each evaluation item in the table. Judgment results were expressed in a five-step evaluation.

  In the five-level evaluation, 5 is “particularly good”, 4 is “good”, 3 is “pass level”, 2 is “slightly bad”, 1 is “NG”, and 3 or more are passed as products. It is a possible level.

  In addition, the environment is changed from low temperature and low humidity (15 ° C x 10%) to high temperature and high humidity (32 ° C x 85%). The results are shown in the “Environmental impact” column.

  Further, the image evaluation of “after endurance of 10,000 sheets” was evaluated in the same manner as “initial stage” after continuously printing 10,000 images of 5% printing density.

  About the obtained developing roller, the resistance value when a voltage of 100 V was applied between the counter electrode (metal drum) was measured using the rotational resistance measuring device shown in FIG.

  Further, by using the apparatus shown in FIG. 10, a voltage of 8 kV is applied to the roller to charge the roller surface by corona discharge, and the measuring unit 44 is moved at a speed of 200 mm / sec. The potential was measured. The shape and dimensions of the measurement unit are as shown in FIG. By this method, the roller surface was measured all over, and the surface potential decay rate from 0.1 seconds to 0.2 seconds after the corona charging was determined. The measurement environment was controlled at a temperature of 22 ° C. and a humidity of 50%.

  As is clear from Tables 7 and 8, all the developing roller samples of the examples were able to obtain good image evaluation results.

  The developing roller according to the present invention includes a charging roller, a developing roller, a transfer roller, a paper feeding roller, a toner in an image forming apparatus such as a plain paper copying machine, a plain paper facsimile machine, a laser beam printer, a color laser beam printer, and a toner jet printer. It is preferably used as a supply roller.

It is a conceptual diagram which shows the image forming apparatus used for a nonmagnetic jumping image development method. It is sectional drawing which shows the conventional developing roller. It is sectional drawing which shows the developing roller of embodiment which concerns on this invention. It is sectional drawing which shows the developing roller of other embodiment. It is sectional drawing which shows the developing roller of other embodiment. It is a perspective view which shows the developing roller of other embodiment. It is a side view which shows the shaft member which has the edge part of a different structure. It is sectional drawing which shows the metal mold | die which forms a hollow cylindrical body. It is a perspective view which shows the shape modification of a shaft part, a shaft hole part, and a gear part. FIG. 2 is a conceptual diagram of an apparatus that applies charge to a developing roller and measures a surface potential. It is a figure which shows arrangement | positioning of the surface potentiometer and a discharger on a measurement unit. It is a conceptual diagram which shows a rotational resistance measuring device. It is a graph which shows attenuation | damping of a surface residual potential logarithm value. It is a perspective view which shows the developing roller of other embodiment. It is a perspective view which shows the shaft member of the developing roller shown in FIG. It is the perspective view and sectional drawing which show a cylindrical member. It is a perspective view which shows the modification of the shaft member shown in FIG. It is a perspective view which shows the other modification of the shaft member shown in FIG. It is a perspective view which illustrates the connection method of a cylindrical member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Shaft member 3 Elastic layer 4 Resin layer 5 Solid cylinder 5a Metal pipe convex part 6 Shaft part 6a Shaft part 6b Shafted cap recessed part 7 Gear part 8 Shaft hole part 11 Developing roller 12 Shaft member 13 Hollow cylindrical body 13a Cylindrical portion 13b Bottom portion 14 Cap member 14a Lid portion 21 Developing roller 22 Shaft member 23 Hollow cylindrical body 23a Cylindrical portion 23b Bottom portion 24 Cap member 24a Lid portion 30 Mold 31 Cylindrical shape 32 Core type 33 Runner type 34 Second Sprue 35 Cavity 36 First Sprue 37 Runner 41 Chuck 42 Corona Discharger 43 Surface Potential Meter 44 Measuring Unit 45 Rotational Resistance Measuring Device 46 Metal Drum 47 Ammeter 51 Developing Roller 52 Shaft Member 53 Hollow Cylinder 54 Cylindrical Member 55 Reinforcing Rib 56 Gold shaft 57 Gear part 61A One end portion 61B cylindrical other end 62 convex portion 63 rotation stopping pin 65 recess 66 rotation stopping hole of the member of the tubular member

Claims (11)

In a developing roller for supplying one or more resin layers on the outer side in the radial direction of a shaft member that is supported by being supported at both ends in the length direction and supplying a nonmagnetic developer carried on the outer peripheral surface to a latent image holding member ,
The shaft member is made of a hollow hollow cylinder made of a resin containing a conductive agent or a solid cylindrical body, and a voltage of 8 kV is applied to a corona discharger disposed at a distance of 1 mm from the outer peripheral surface. When the corona discharge is generated to charge the outer peripheral surface, the absolute value of the surface potential decay rate from 0.1 seconds to 0.2 seconds after the charge is applied is 0.1 [V / sec] or more. Developing roller.   The developing roller according to claim 1, wherein at least one resin layer is made of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent.   The resin layer comprising an ultraviolet curable resin or an electron beam curable resin containing a conductive agent is formed by applying a solventless coating liquid and irradiating with ultraviolet rays or an electron beam. The developing roller as described.   The developing roller according to claim 1, wherein an elastic layer is disposed between the shaft member and the innermost resin layer.   5. The developing roller according to claim 1, wherein the resin forming the shaft member is at least one synthetic resin selected from the group consisting of general-purpose resin, general-purpose engineering plastic, and super-engineering plastic.   General engineering plastics or super engineering plastics are polyacetal, polyamide 6, polyamide 6, 6, polyamide 12, polyamide 4, 6, polyamide 6, 10, polyamide 6, 12, polyamide 11, polyamide MXD6, polybutylene terephthalate, polyphenylene oxide, 6. The development according to claim 5, which is polyphenylene sulfide, polyphenylene ether, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone, polyethylene terephthalate, polyarylate polytetrafluoroethylene, or liquid crystal polymer. roller.   The conductive agent contained in the resin forming the shaft member is at least one selected from the group consisting of carbon black, graphite, tin oxide, titanium oxide, zinc oxide, nickel, aluminum, and copper. The developing roller according to any one of the above.   The developing roller according to claim 1, wherein the shaft member is made of a hollow cylindrical body, and a reinforcing rib extending radially inward from the outer peripheral surface of the hollow cylindrical body is provided. .   9. The shaft member is provided with a metal shaft that is disposed at a center in a radial direction of the hollow cylindrical body and fits through the hollow cylindrical body, and the metal shaft is configured to support a radially inner end of the reinforcing rib. The developing roller according to 1.   The developing roller according to claim 9, wherein the hollow cylindrical body is configured by connecting a plurality of cylindrical members in a length direction.   An image forming apparatus comprising the developing roller according to claim 1.

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