JP2012168252A - Method for manufacturing conductive elastic roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a conductive elastic roller, by which generation of uneven distribution of an electric resistance value in a circumference direction at an end part of an elastic layer caused in a cutting process in cross-head extrusion molding.SOLUTION: The method aims to manufacture a conductive elastic roller for electrophotography having a shaft core body 202 and a conductive elastic layer covering a circumference face of the shaft core body. The method comprises: coating circumference faces of a plurality of shaft core bodies connected in series in a cross head with a continuous layer 311 of an unvulcanized rubber mixture containing conductive particles discharged from an extruder; and cutting the continuous layer by winding a cutting wire 601 around the continuous layer while allowing the cutting wire 601 to which tension is applied to intrude into the continuous layer from one point on an outer circumference in a seam of the two shaft core bodies connected in series, and moving the cutting wire from the outer circumference of the continuous layer in a direction to the shaft core body.

Description

  The present invention relates to a method for manufacturing a conductive elastic roller.

  Conductive elastic rollers used in image forming apparatuses such as electrophotographic printers, copiers, and electrostatic recording apparatuses have a conductive elastic layer on the outer peripheral surface of the shaft core, and are used by being pressed against the photoreceptor. Often. When the conductive elastic roller is used as a charging roller, the electric resistance value is required to be uniform in order to uniformly charge the photosensitive member.

  As a method for producing a conductive elastic roller, a continuous layer of an unvulcanized rubber mixture is coated on the outer peripheral surface of a shaft core continuously supplied by coating extrusion molding using a shaft core crosshead. A method is used in which a continuous layer of a vulcanized rubber mixture is cut to obtain an unvulcanized conductive elastic roller.

  In Patent Document 1, a pair of cutting blades facing the seam of the shaft core body is entered from the outer peripheral surface of the continuous layer of the unvulcanized rubber mixture to cut the continuous layer of the unvulcanized rubber mixture. A method of obtaining a conductive elastic roller by subjecting a vulcanized conductive elastic roller to secondary processes such as vulcanization and grinding has been disclosed.

JP 2005-227754 A

  However, in the cutting method of Patent Document 1, the present inventor has a possibility that compressive force is generated in the unvulcanized rubber mixture by the tips of the cutting blades contacting each other on the cut surface of the continuous layer of the unvulcanized rubber mixture. Recognized that there is.

  FIG. 1A is a schematic diagram for explaining the force that the cut surface of the unvulcanized conductive elastic roller cut by the cutting method described in Patent Document 1 receives by cutting. In the region A that receives the compressive force by the pair of cutting blades, the electric resistance value may fluctuate due to the change in the aggregation state of the conductive particles in the unvulcanized rubber mixture. There may be a region where the unevenness of the resistance value becomes large.

  In addition, due to the recent increasing demand for miniaturization of electrophotographic apparatuses, conductive elastic rollers are also becoming smaller, and the length of the shaft core portion of the conductive elastic roller is becoming shorter. For this reason, it has become difficult to sufficiently remove a region having a large non-uniformity in electric resistance value generated when the unvulcanized rubber mixture layer is cut. As a result, a portion having a relatively large electric resistance unevenness may remain at the end of the conductive elastic roller.

  When a conductive roller having such uneven electrical resistance is used for the charging roller, uneven charging may occur on the photosensitive member, and as a result, streaks may occur on the electrophotographic image.

  Accordingly, an object of the present invention is to suppress the occurrence of uneven electrical resistance values in the circumferential direction at the end of the elastic layer of the conductive elastic roller in the cutting process of the crosshead extrusion, thereby contributing to the formation of a high-quality electrophotographic image. An object of the present invention is to provide a method for manufacturing a conductive elastic roller.

That is, the manufacturing method of the conductive elastic roller of the present invention,
A method for producing a conductive elastic roller for electrophotography having a shaft core and a conductive elastic layer covering a peripheral surface thereof,
(1) a step of continuously introducing a plurality of shaft cores in series to the crosshead;
(2) supplying an unvulcanized rubber mixture containing unvulcanized rubber and conductive particles from the extruder connected to the crosshead to the crosshead;
(3) A plurality of shaft cores connected in series and the unvulcanized rubber mixture are co-extruded from the cross head, and the peripheral surfaces of the plurality of shaft cores connected in series are placed on the unvulcanized rubber. Coating with a continuous layer of the mixture;
(4) From one location on the outer periphery of the joint portion of the two axial cores connected in series in the continuous layer, the cutting wire is inserted into the continuous layer while the cutting wire is applied to the continuous layer. Wrapping around the continuous layer, the intersection of the cutting wires enters the continuous layer from a position approximately 180 ° opposite the position where the cutting wire first entered the continuous layer, and the cutting wire The cutting wire is squeezed from the outer peripheral surface of the continuous layer toward the axial core body by squeezing the ring of the cutting wire so that the intersecting portion of the cutting wire and the first contact portion of the cutting wire with the continuous layer approach each other. Moving and cutting the continuous layer.

  According to the present invention, it is possible to suppress the occurrence of uneven electrical resistance values in the circumferential direction at the elastic layer end portion of the conductive elastic roller, which occurs in the cutting process of crosshead extrusion.

It is a schematic diagram for demonstrating the force which the cut surface of the unvulcanized electroconductive elastic roller cut | disconnected by the conventional cutting method receives by cutting | disconnection. It is a schematic diagram which shows the external appearance of the electroconductive elastic roller produced with the manufacturing method of this invention. It is a mimetic diagram for explaining one embodiment of a manufacturing method of the present invention. It is a schematic diagram of an example of the cutting device applicable to the manufacturing method of this invention. It is a cross-sectional schematic diagram for demonstrating one Embodiment of the process of cut | disconnecting the continuous layer in the manufacturing method of this invention. (A) is an electrophotographic apparatus using a conductive elastic roller produced by the production method of the present invention, and (b) is a schematic sectional view of an example of a process cartridge. It is a schematic diagram of the apparatus which measures the nonuniformity of the electrical resistance value of the circumferential direction of a conductive elastic roller. 6 is a schematic diagram for explaining a method of manufacturing the conductive elastic roller shown in Comparative Example 1. FIG.

(Conductive elastic roller)
As shown in FIG. 2, a conductive elastic roller 201 manufactured according to the present invention has a shaft core body 202 and a conductive elastic layer 203 on the outer peripheral surface thereof. The conductive elastic layer 203 can be obtained by vulcanizing (curing) an unvulcanized rubber mixture containing unvulcanized rubber and conductive particles described later. The longitudinal end of the conductive elastic roller can include a shaft core body portion 204 from which the shaft core body is exposed by removing the conductive elastic layer, and the shaft core body portion 204 is provided in the image forming apparatus. Is used to support the conductive elastic roller and to apply a voltage to the conductive elastic roller. Below, each member which comprises the electroconductive elastic roller 201 is demonstrated.

[Shaft core]
The shaft core body 202 used for the conductive elastic roller is conductive and has a function of supporting a conductive elastic body layer provided on the outer peripheral surface of the shaft core body. Examples of the material of the shaft core include metals such as iron, copper, stainless steel, aluminum, nickel, and alloys thereof. In addition, for the purpose of imparting scratch resistance to the surface of the shaft core formed using these materials, plating treatment or the like may be performed as long as the conductivity is not impaired. Further, as the shaft core, a resin base material coated with a metal or the like to make the surface conductive, or one manufactured from a conductive resin composition can be used.

[Unvulcanized rubber mixture]
As raw materials (unvulcanized rubber) of the unvulcanized rubber mixture used in the present invention, natural rubber, butadiene rubber, styrene butadiene rubber (SBR), nitrile rubber, ethylene propylene rubber (EPDM), chloroprene rubber (CR) And nitrile butadiene rubber (NBR), epichlorohydrin rubber, butyl rubber, isoprene rubber (IR), silicone rubber, urethane rubber, and fluorine rubber. A plurality of these unvulcanized rubbers may be used.

  Examples of the conductive particles dispersed in the raw material of the unvulcanized rubber mixture include ketjen black EC, acetylene black, carbon for rubber, carbon for color (ink) subjected to oxidation treatment, and pyrolytic carbon. Carbon can be used. By dispersing the conductive particles in the unvulcanized rubber, electronic conductivity can be imparted to the rubber.

As the conductive particles, graphite such as natural graphite and artificial graphite can also be used. Further, gold oxide, such as TiO _2, SnO _2, ZnO, mixed oxides, such as solid solution of ZnO and Al ₂ O _3, Cu, including the metal powder and the like, such as Ag, can be used known conductive particles, They may be used alone or in combination of two or more.

  Moreover, you may provide electroconductivity using a conductive polymer, an ionic conductive agent, etc. together with the said electroconductive particle. Moreover, a vulcanizing agent, a vulcanization accelerator, a charge control agent, a plasticizer, an antiaging agent, and the like can be appropriately added to the unvulcanized rubber mixture. Furthermore, an antistatic agent, an ultraviolet absorber, a reinforcing agent, a filler, a lubricant, a release agent, a pigment, a dye, a flame retardant, and the like can be added as necessary.

(Conductive elastic roller manufacturing equipment)
An example of a manufacturing apparatus applicable to the method for manufacturing the conductive elastic roller of the present invention is shown in FIG.

  As shown in FIG. 3, the manufacturing apparatus used in the present invention includes at least an extruder 301, a cross head 302, and a shaft core body supply device 303 and a cutting device 600 for continuously supplying the shaft core body 202 to the cross head. Can be included. Further, the manufacturing apparatus can include a discharge unit 307 of the cut unvulcanized conductive elastic roller 312 and an elevator 607 for moving the cutting apparatus 600 up and down.

  Hereinafter, each mechanism of the manufacturing apparatus shown in FIG. 3 will be described in detail.

  The extruder 301 has an inlet (not shown) for feeding an unvulcanized rubber mixture, a cylinder (not shown) and a screw (not shown) for conveying the unvulcanized rubber mixture while plasticizing and kneading. The extruder 301 is connected to the cross head 302.

  The cross head 302 forms an unvulcanized rubber mixture into a cylindrical shape, and the unvulcanized rubber mixture is formed on the outer peripheral surface of a plurality of serially connected shaft core bodies 202 supplied from the shaft core body supply device 303. The continuous layer is coated and discharged from the base 305.

  The shaft core body supply device 303 includes an shaft core body feed roll 304 for transporting the shaft core body 202 to the cross head 302, and continuously supplies a plurality of shaft core bodies in series to the cross head. In this shaft core body supply device 303, a roll type is used as the shaft core body transporting means. However, in carrying out the present invention, the present invention is not limited to the roll type. A well-known conveyance means such as conveyance of the shaft core body can be applied.

  Further, the shaft core body supply device 303 detects a joint portion of two shaft core bodies 202 connected in series in a state where a continuous layer of an unvulcanized rubber mixture extruded from the base 305 is covered. As a detection means for this purpose, a shaft core tip detection sensor 609 is provided. The two shaft cores may be in contact with each other as long as they are arranged adjacent to each other in the axial direction (series) of the shaft cores, or between the two shaft cores. There may be an interval. In other words, the opposing end surfaces of the two shaft core bodies 202 may be in contact with each other, or a slight amount of unapplied between the opposing end surfaces of the two adjacent shaft core bodies. A state in which the vulcanized rubber composition is sandwiched may be used. Specifically, the distance between the opposing end surfaces of two adjacent shaft cores can be in a state of 0 to several mm. In this manufacturing apparatus, the outer diameter of the unvulcanized conductive elastic roller discharged from the die can be changed by the supply speed of the shaft core 202 to the cross head.

  Moreover, the joint part of two axial core bodies connected in series shows the area | region pinched | interposed by two opposing end surfaces of two adjacent axial core bodies 202. FIG. That is, the seam portion can be a surface (contact surface) formed by contact between the opposing end surfaces of the shaft core body when two shaft core bodies are adjacent to each other. Moreover, when the two axial core bodies are arrange | positioned at intervals, it can be a part between two opposing end surfaces of an axial core body.

  The shaft core tip detection sensor 609 detects the joint between two adjacent shaft cores 202 connected in series from the rotation amount of the shaft core feed roll 304.

  An example of a cutting apparatus applicable to the manufacturing method of the present invention is schematically shown in FIG. The cutting device 600 of FIG. 4 includes a cutting wire 601, a cutting wire supply take-up reel 602, an inner ring 603, and an outer ring 604. Further, an inner ring driving gear 605 and an outer ring driving gear 606 for driving the inner ring 603 and the outer ring 604 are provided.

  The inner ring 603 and the outer ring 604 are each cylindrical. Further, these two rings serve as cutting wire guides for guiding the cutting wire 601, and penetrate each ring from one surface to the other surface of each ring, that is, each ring passes through the shaft core 202. A cutting wire guide hole 608 penetrating in the axial direction is provided.

  The two rings of the inner ring 603 and the outer ring 604 are formed by cutting the inner ring 603 and the outer ring 604 with the shaft core 202 covered with the continuous layer 311 of the unvulcanized rubber mixture discharged from the base 305 as the central axis. The wire guide holes 608 are installed so as to have the same height. The inner ring 603 and the outer ring 604 are connected to drive gears, respectively, and rotate in the circumferential direction of each ring about the shaft core 202 as a central axis, so that the cutting wire 601 is outer peripheral surface of the continuous layer 311 of unvulcanized rubber mixture Wrap around. At that time, the inner ring 603 and the outer ring 604 circulate in opposite directions. The inner ring 603 and the outer ring 604 are each connected to an encoder (not shown) to detect the position of the cutting wire guide hole 608. In FIG. 4, a hole that penetrates each ring in the axial direction of the shaft core 202 is used as the cutting wire guide portion.

  One end of the cutting wire 601 is fixed to the first cutting wire supply take-up reel 602, and passes through the cutting wire guide hole 608 of the inner ring 603 and the cutting wire guide hole 608 of the outer ring 604, and then the second cutting wire supply winding. The other end is fixed to the take-up reel 602.

  The first cutting wire supply take-up reel and the second cutting wire supply take-up reel can monitor and adjust the tension applied to the cutting wire 601 by a tension adjusting mechanism (not shown).

The tension of the cutting wire 601 is adjusted by the supply take-up reel 602, and the cutting wire guide hole 608 makes a revolving motion, so that the seam portion of the shaft core body 202 covered with the continuous layer 311 of the unvulcanized rubber mixture is applied. Enter the continuous layer while being wound.
When the size of the joint portion of the shaft core body 202 (the distance between the opposing end surfaces of two adjacent shaft core bodies) is larger than the diameter of the cutting wire, the cutting wire covers the seam portion. Enter the continuous layer of rubber composition.
On the other hand, when the size of the joint portion of the shaft core body 202 is smaller than the diameter of the cutting wire, the cutting wire spreads the end surface and the end surface of the adjacent shaft core body, and unvulcanized to cover the joint portion. Enter the continuous layer of rubber composition.

  It is allowed to stop the movement of the joint portion of the shaft cores that are connected in series at the time of cutting, for example, by temporarily stopping the supply of the shaft core 202. However, from the viewpoint of suppressing fluctuations in the outer diameter of the continuous layer 311 of the unvulcanized rubber mixture, the supply of the shaft core is preferably performed continuously without temporarily stopping.

  In the manufacturing apparatus shown in FIG. 3, since the cutting device 600 is installed in the elevator 607, the joint portion of the two continuous shaft core bodies and the cutting wire can be synchronized and lowered, and the shaft core body can be continuously moved. Can be supplied to.

[Cutting wire]
The wire used as the cutting wire only needs to be able to cut the continuous layer, and can be selected and used as necessary from known wires, piano wires, and strings, and the material and cross-sectional shape of the cutting wire are also required. You can choose. In consideration of durability at the time of repeated cutting, it is preferable to use a stranded wire. The wire diameter of the cutting wire is not particularly defined, but considering the cutting resistance and durability during repeated cutting, the wire diameter of the cutting wire is preferably 0.1 mm or more and 2 mm or less. By setting it to 0.1 mm or more, durability during repeated cutting can be easily secured, and by setting it to 2 mm or less, cutting resistance can be easily reduced. Further, the outer peripheral surface of the cutting wire may be coated with polyamide, PTFE, or the like from the viewpoint of reducing cutting resistance due to friction with the unvulcanized rubber mixture.

[Derivation of cutting conditions]
The cutting condition can be adjusted by adjusting the tension T applied to the cutting wire 601 and the rotational angular velocities ω1 and ω2 of the inner ring 603 and the outer ring 604, respectively. An example of the procedure for optimizing the tension T and the rotational angular velocities ω1 and ω2 is shown below.
Procedure 1.
As initial conditions, an arbitrary tension T and rotational angular velocities ω1 and ω2 of the inner ring and the outer ring are input.
Procedure 2.
Started production of unvulcanized conductive elastic rollers.
Procedure 3.
Cut the unvulcanized conductive elastic roller.
Procedure 4.
Detects cutting completion. The cutting of the unvulcanized conductive elastic roller is completed at the joint portion between the adjacent shaft core bodies 202, but the central position of the shaft core body of the joint portion is difficult to observe from the outside. For this reason, in order to derive the cutting condition, cutting completion detection by a cutting completion detection means provided separately is used.
A specific example of the cutting completion detection means is shown below.

  As a means for detecting the completion of cutting, a pressure sensor is installed in the work receiving portion of the discharging device 307 to detect the load applied by the unvulcanized conductive elastic roller 312 added to the sensor after cutting. A method is mentioned. When the cutting is completed, the unvulcanized conductive elastic roller 312 cut by the cutting wire 601 falls and presses the sensor. This can be detected to detect the completion of cutting.

Other methods for detecting the completion of cutting include monitoring the change in tension of the cutting wire supply take-up reel, measuring the shape of the continuous layer of the unvulcanized rubber mixture with laser light, and using X-ray transmission observation, etc. I can do it.
Procedure 5.
When the cutting completion is detected, the relative position between the cutting wire 601 and the shaft core 202 on the base 305 side is confirmed.
Procedure 6.
In step 5, it is determined whether or not the relative position of the cutting wire 601 and the shaft core 202 on the base 305 side is appropriate. If the relative position is appropriate, it is determined that the cutting condition is appropriate, and the steps after step 2 are continued.

  If the relative position is inappropriate, it is determined that the cutting condition is inappropriate, and after changing any one or more of the tension T, the rotational angular velocity ω1, and the rotational angular velocity ω2, the steps after step 2 are repeated, The optimization is repeated until the cutting conditions are appropriate.

  When the relative position between the cutting wire 601 and the shaft core body 202 on the base 305 side is appropriate, the ring formed by the cutting wire 601 is closer to the cutting wire side of the shaft core body 202 as shown in FIG. It means the case where it disappears on the surface. At this time, the cutting wire side surface of the shaft body on the base 305 side and the cutting wire may or may not be in contact.

  On the other hand, when the relative position of the cutting wire 601 and the shaft core body 202 on the base 305 side is inappropriate, the ring formed by the cutting wire 601 is closer to the cutting wire side of the shaft core body 202 as shown in FIG. It means a case where it disappears at a part other than the surface. Examples of the portion other than the surface on the cutting wire side of the shaft core include, for example, the space between the inner ring 603 and the continuous layer of the unvulcanized rubber mixture, and the surface of the continuous layer on the cutting wire side. . When the ring of the cutting wire disappears on the surface of the continuous layer on the side of the cutting wire, the surface of the continuous layer on the side of the cutting wire and the cutting wire may or may not be in contact.

  The tension T can take any value, but a preferable range of the tension T is 0.5 to 20N, and more preferably 5 to 15N. This is to easily prevent the tension of the cutting wire from becoming non-uniform due to friction between the unvulcanized rubber composition and the cutting wire.

  The rotation angular velocity ω1 and the rotation angular velocity ω2 are allowed to take arbitrary values, and both are preferably 1 to 50 rad / sec, more preferably 5 to 30 rad / sec. This is because the cutting time is easily shortened and the breakage of the cutting wire is easily prevented. When the rotational angular velocity is 50 rad / sec or less, the cutting wire can be easily prevented from being damaged by friction with the cutting wire guide.

The relative position between the cutting wire 601 and the shaft core 202 on the base 305 side when cutting completion is detected can be confirmed, for example, by the following method.
When there is a sufficient difference in the electrical resistance value between the continuous layer 311 of the unvulcanized conductive rubber mixture, the cutting wire 601, and the shaft core body 202, the cutting is performed by detecting the change in the conduction state between the cutting wire 601 and the shaft core body 202. The relative position between the wire 601 and the shaft core body 202 can be confirmed. Specifically, when the relative position between the cutting wire 601 and the shaft core 202 at the completion of cutting is appropriate, a conductive state is indicated. On the other hand, when the relative position is inappropriate, no conduction state is shown.
For example, this method can be applied when the cutting wire 601 is made of SUS304 specified in JIS G 4303 and the shaft core 202 is made of SUM22 specified in JIS G 4804.

  The continuous layer 311 of the unvulcanized conductive rubber mixture, the cutting wire 601, and the shaft core body 202 are not sufficiently different in electrical resistance value, and it is difficult to detect the change in the conductive state between the cutting wire 601 and the shaft core body 202. Can confirm the contact state between the cutting wire 601 and the shaft core body 202 by X-ray transmission observation.

  The initial conditions (T, ω1, and ω2) of the cutting conditions can be estimated from a database of the viscosity of the unvulcanized rubber mixture and the results of the cutting conditions, thereby smoothly deriving appropriate cutting conditions. be able to.

(Method for producing conductive elastic roller)
As an embodiment of the present invention, a method for producing a conductive elastic roller using the crosshead extrusion molding apparatus shown in FIG. 3 will be described.

  First, a plurality of shaft cores 202 are continuously introduced into the cross head 302 in series (step 1).

  Next, an unvulcanized rubber mixture containing unvulcanized rubber and conductive particles is put into an extruder 301 connected to the cross head 302. The unvulcanized rubber mixture charged into the extruder 301 is plasticized and kneaded and introduced into the crosshead 302 (step 2).

  A plurality of shaft cores connected in series from the crosshead 302 and the unvulcanized rubber mixture are coextruded, and a continuous layer 311 of the unvulcanized rubber mixture formed into a cylindrical shape by the crosshead 302 is formed on the shaft core 202. The outer peripheral surface is covered (step 3) and discharged from the base 305.

  After discharging from the base 305, the joint portion of the two shaft core bodies 202 connected in series and covered with the continuous layer 311 of the unvulcanized rubber mixture is cut by the cutting device 600 (step 4).

  Next, with reference to FIG. 5, the above-described step 4 will be described in order by dividing it into seven steps (I to VII) by taking as an example a method of cutting the continuous layer 311 with the cutting device 600 shown in FIG. 4.

Step I.
One cutting wire 601 to which a tension T is applied is applied to the continuous layer 311 from one place (contact point 1) on the outer periphery of the joint portion of the adjacent two shaft cores 202 of the continuous layer 311 of the unvulcanized rubber mixture. Contact. More specifically, an inner ring 603 and an outer ring 604 each having a cutting wire guide hole 608 are circulated in opposite directions with the axial direction of the shaft core 202 as the central axis, and a continuous layer of an unvulcanized rubber mixture. The cutting wire 601 is brought into contact with the outer peripheral surface of 311 from the contact point 1. The tension of the cutting wire 601 can be kept constant by a tension adjusting mechanism (not shown) (FIG. 5A).

  The contact point 1 can be calculated from the positions of the guide holes respectively installed in the inner ring 603 and the outer ring 604 and the change in tension monitored by a tension adjusting mechanism (not shown). The position of the guide hole can be calculated by an encoder (not shown) connected to the inner ring 603 and the outer ring 604. Specifically, contact between the cutting wire 601 and the continuous layer 311 of the unvulcanized rubber mixture is detected by a change in tension applied to the cutting wire 601, and the positions of the inner ring 603 and the outer ring 604 in the circumferential direction at this time Is detected by an encoder (not shown), the position of the contact point 1 can be calculated.

Step II.
The inner ring 603 and the outer ring 604 continue to circulate, and the cutting wire 601 maintained at a constant tension enters the continuous layer 311 from the contact point 1 and is wound around the continuous layer 311 ( FIG. 5B). The cutting wire 601 is continuously in contact with the continuous layer 311 of the unvulcanized rubber mixture and enters the continuous layer 311 of the unvulcanized rubber mixture. It enters by the movement toward the inner peripheral surface of the layer 311.

Step III.
Further, the inner ring 603 and the outer ring 604 continue to circulate, the wound wires 601 are crossed, and a ring is formed by the cutting wire 601 (FIG. 5C). At that time, on the surface perpendicular to the axial direction of the axial core body 202, the position of the outer peripheral surface of the continuous layer approximately 180 ° opposite to the position where the cutting wire 601 first entered the continuous layer 311 (contact point 1). The cutting wire 601 is crossed at the position (contact point 2). In addition, substantially 180 degrees means 160 degrees or more and 220 degrees or less.

Step IV.
The inner ring 603 and the outer ring 604 continue to circulate, the ring formed by the cutting wire 601 is squeezed, and the cutting wire 601 is moved from the outer peripheral surface of the continuous layer 311 toward the axial core body 202 (inside the continuous layer). It is moved in the direction toward the circumferential surface (FIGS. 5D and 5E). At that time, the intersecting portion of the cutting wire 601 enters the continuous layer from the contact point 2 so that the first contacting portion with the continuous layer of the cutting wire and the intersecting portion of the cutting wire approach each other.

Step V.
The continuous layer 311 is cut by the movement of the cutting wire 601 from the outer peripheral surface of the continuous layer 311 toward the shaft core body 202 to obtain an unvulcanized conductive elastic roller (FIGS. 5F and 5G). )). At this time, the ring formed by the cutting wire 601 continues to enter between the adjacent shaft cores until the cutting is completed (if the two shaft cores are in contact, the space between the opposing end surfaces is pushed. Smaller (while continuing to expand and enter).

Process. VI
The ring formed by the cutting wire 601 disappears not on the cut surface of the continuous layer 311 on the base 305 side but on the end surface of the shaft core 202 on the base 305 side, and the cutting wire 601 connects the two guide holes. It becomes linear (FIG. 5 (h)).

Process. VII
The inner ring and the outer ring are retracted so as not to interfere with the member from which the cutting wire is pushed out (axial core body 202 covering the continuous layer 311) (FIG. 5 (i)) to prepare for the next cutting.

  Next, the unvulcanized conductive elastic roller is discharged by a discharge device, and the unvulcanized conductive elastic roller is vulcanized. After vulcanization, the elastic layer is subjected to steps such as end removal and polishing to obtain a conductive elastic roller.

  According to the production method of the present invention, the continuous layer is cut by the movement of the cutting wire from the outer peripheral surface of the continuous layer toward the axial core in the cut surface of the continuous layer of the unvulcanized rubber mixture.

  At this time, since the ring of the cutting wire can be eliminated on the shaft core, more specifically, on the end surface of the shaft core on the cutting wire side, it is compared with the conventional method shown in FIG. Thus, when the ring disappears, a compressive force is hardly generated in the continuous layer of the unvulcanized rubber mixture. For this reason, the change in the aggregation state of the conductive particles in the unvulcanized rubber mixture due to the compressive force is unlikely to occur, and there is a difference in the electric resistance value between the unvulcanized rubber mixture in the region where compression is not generated and the region where compression occurs. It becomes difficult to occur.

  FIG. 1B illustrates the force that the cut surface of the unvulcanized conductive elastic roller receives when the continuous layer of the unvulcanized rubber mixture is cut by the method shown in Comparative Example 1 described later. The schematic diagram is shown. In this method, the cutting wire is wound without applying tension to the outer periphery of the continuous layer of the joint portion of the two adjacent shaft core bodies, and then tension is applied to the cutting wire so that one cutting wire is attached. The continuous layer is cut by cutting into the continuous layer. That is, there is no compressive force generated when the wires cross at the cutting plane, but the wire advances toward the position where the wires cross when cutting, so the continuous layer 311 is axially moved as shown in FIG. There is a possibility that a force in the direction of peeling from the core body 202 may occur. For this reason, peeling of the shaft core body and the continuous layer may occur in the region B, and the unevenness in the circumferential direction of the electric resistance value at the end of the unvulcanized conductive elastic roller may increase.

  On the other hand, as described above, in the present invention, since the cutting wire moves from the outer peripheral surface of the continuous layer of the unvulcanized rubber mixture toward the shaft core body, the shaft core body is compared with the method shown in FIG. The force in the direction of peeling the continuous layer of the unvulcanized rubber mixture from is hardly generated. Thereby, peeling between the shaft core body and the continuous layer hardly occurs, and a difference in electric resistance value of the unvulcanized rubber mixture hardly occurs.

  As described above, it is possible to reduce the cause of fluctuation of the electric resistance value on the cut surface of the continuous layer of the unvulcanized rubber mixture, thereby reducing the occurrence of unevenness in the circumferential direction of the electric resistance value at the end of the unvulcanized conductive elastic roller. It is guessed that it is made. Thereby, it is considered that unevenness of the electrical resistance value in the circumferential direction of the conductive elastic roller obtained by vulcanizing and polishing the unvulcanized conductive elastic roller can be reduced.

[Electrophotographic equipment]
FIG. 6A shows a schematic configuration of an example of an electrophotographic apparatus to which the conductive elastic roller manufactured by the manufacturing method of the present invention can be applied. This electrophotographic apparatus collects a photosensitive member, a charging device that charges the photosensitive member, a latent image forming device that performs exposure, a developing device that develops a toner image, a transfer device that transfers to a transfer material, and a transfer toner on the surface of the photosensitive member. It is composed of a cleaning device, a fixing device for fixing a toner image, and the like.

  Each mechanism constituting the electrophotographic apparatus will be described below.

  The photoreceptor 101 is a rotary drum type having a photosensitive layer on the outer periphery of the shaft core. The photoreceptor is driven to rotate in the direction of the arrow at a predetermined peripheral speed (process speed).

  The charging device includes a contact-type charging member 102 that is placed in contact with the photosensitive member 101 by being brought into contact with the photosensitive member 101 with a predetermined pressing force. The charging member 102 is driven rotation that rotates in accordance with the rotation of the photosensitive member, and charges the photosensitive member to a predetermined potential by applying a predetermined voltage from the charging power source 112.

  For example, an exposure apparatus such as a laser beam scanner is used as the latent image forming apparatus 107 that forms an electrostatic latent image on the photosensitive member 101. An electrostatic latent image is formed by performing exposure corresponding to image information on a uniformly charged photoconductor. The developing device includes a developing member 103 disposed close to or in contact with the photoreceptor 101, a regulating member 109 that regulates toner on the developing member, a supply member 110 that supplies toner to the developing member, and a developing power source 111. Have. The toner electrostatically processed to the same polarity as the photosensitive member charge polarity is developed by reversal development to visualize and develop the electrostatic latent image into a toner image.

  The transfer device includes a contact-type transfer member 104 and a transfer power supply 113. The toner image is transferred from the photosensitive member to a transfer material 114 such as plain paper (the transfer material is conveyed by a paper feed system having a conveyance member).

The cleaning device includes a blade-type cleaning member 106 and a collection container, and after transfer, mechanically scrapes and collects transfer residual toner remaining on the surface of the photoreceptor.
Here, it is possible to omit the cleaning device by adopting a development simultaneous cleaning system in which the transfer device collects the transfer residual toner.

  The fixing device 105 includes a heated roller or the like, fixes the transferred toner image on the transfer material 114, and discharges the toner image outside the apparatus.

[Process cartridge]
An electrophotographic apparatus to which a conductive elastic roller is applied may be a process cartridge in which the charging roller 102 is at least integrated with a member to be charged (photosensitive member 101) and is configured to be detachable from the main body of the electrophotographic apparatus. . The electrophotographic apparatus can include at least the process cartridge, the exposure apparatus, and the developing apparatus.

  As the process cartridge, for example, the process cartridge shown in FIG. 6B in which the photosensitive member 101, the charging device, the developing device, the cleaning device, and the like are integrated and designed to be detachable from the electrophotographic apparatus can be used. Further, an electrophotographic conductive elastic roller manufactured by the manufacturing method of the present invention can be used as the charging roller 102.

Production example of unvulcanized rubber mixture [Production Example 1]
The materials shown in Table 1 were kneaded for 10 minutes in a two-roll machine cooled to 25 ° C. to obtain an unvulcanized rubber mixture A1.

[Production Example 2]
The materials shown in Table 2 were kneaded for 10 minutes in a two-roll machine cooled to 25 ° C. to obtain an unvulcanized rubber mixture A2.

[Production Example 3]
The materials shown in Table 3 were kneaded for 10 minutes in a two-roll machine cooled to 25 ° C. to obtain an unvulcanized rubber mixture A3.

[Production Example 4]
The materials shown in Table 4 were kneaded for 10 minutes in a two-roll machine cooled to 25 ° C. to obtain an unvulcanized rubber mixture B1.

[Example 1]
A thermosetting adhesive (trade name: METALOC N33, manufactured by Toyo Chemical Laboratory Co., Ltd.) was applied to a stainless steel rod having a diameter of 6 mm and a length of 252.5 mm, and a dried product was prepared as a shaft core body 202. .

  Using the unvulcanized rubber mixture A1 and the shaft core, an unvulcanized conductive elastic roller A1 was manufactured by a crosshead extrusion molding apparatus shown in FIG. This will be described in detail below.

  As the extruder 301 of the extrusion molding apparatus, a vent type extruder having a cylinder inner diameter of 50 mm and an L / D of 22 was used. The flight shape of the screw was a full flight shape except for the vent zone. The shaft core feed roll 304 was connected to a motor (not shown) to give a rotational force. A base 305 having an inner diameter of 9.2 mm was attached to the tip of the cross head 302. The extrusion temperature is 90 ° C. in the cylinder, cross head, and die, and the screw speed of the extruder is 20 r. p. m. Then, a continuous layer 311 of an unvulcanized rubber mixture having a φ (diameter) of 9 mm was coated on the outer peripheral surface of the shaft core 202.

  A continuous wire 311 of unvulcanized rubber mixture A1 is applied to a cutting wire 601 provided with a tension of 10.0 N from one place on the outer periphery of the joint portion of two shaft cores 202 connected in series, discharged from the base 305. Wrapped around. Then, as shown in FIG. 5 (c), a ring of cutting wires whose intersecting portion is in contact with the continuous layer is formed, and the ring of this cutting wire 601 is moved from the outer peripheral surface of the continuous layer 311 with the same tension (10.0 N). The continuous layer 311 of the unvulcanized rubber mixture A1 was cut in the direction toward the inner peripheral surface.

  The cutting wire 601 was made of SUS304 having a wire diameter of 1 mm and 7 strands and 7 twists. The inner ring 603 was rotated around the shaft core 202 covered with the continuous layer 311 of the unvulcanized rubber mixture A1 discharged from the die at an angular velocity of 10.5 rad / sec. The outer ring 604 was rotated in the opposite direction to the inner ring 603 at an angular velocity of 8.8 rad / sec.

  Next, the cut unvulcanized conductive elastic roller was vulcanized in a hot air oven at 160 ° C. for 1 hour to produce a rubber roller. In Example 1, both ends of the conductive elastic layer were cut so that the length of the conductive elastic layer in the axial direction of the conductive elastic roller was 242 mm. Further, the conductive elastic layer was polished with a rotating grindstone to form a crown shape having an end portion diameter of 8.3 mm and a central portion diameter of 8.5 mm. An ultraviolet lamp is installed parallel to the axial direction of the rubber roller, and the rubber roller is rotated in the circumferential direction and irradiated with ultraviolet light having a wavelength of 254 nm for 2 minutes to form a modified layer on the surface of the conductive elastic layer. An elastic roller A1 was obtained. For ultraviolet irradiation, a low-pressure mercury lamp (trade name “GLQ500US” manufactured by Harrison Toshiba Lighting Co., Ltd.) was used.

[Evaluation of unevenness of electrical resistance in circumferential direction]
The unevenness of the electrical resistance value in the circumferential direction was calculated by the following method for each of the positions 5 mm inside and 10 mm inside from the end of the elastic layer of the conductive elastic roller A1 (201).

  That is, as shown in FIG. 7, both ends of the shaft core 202 are brought into contact with a columnar metal 901 having the same curvature as that of the photosensitive member by a bearing (not shown) so as to be parallel. In this state, the cylindrical metal 901 is rotated by a motor (not shown), and a DC voltage of −200 V is applied from the stabilized power source 902 while the conductive elastic roller A1 in contact is driven to rotate. The flowing current was measured with an ammeter 904. The ratio (maximum value ÷ minimum value) was obtained from the maximum value and the minimum value of the current value measured by the ammeter 904, and the unevenness in the circumferential direction of the electric resistance value was obtained. When the shaft core body 202 is brought into contact with the columnar metal 901, the load applied to both ends of the shaft core body is 4.9 N each. The columnar metal 901 has a diameter of 30 mm and a length of 5 mm. The peripheral speed was 45 mm / sec.

  The nonuniformity in the circumferential direction of the electric resistance value in the inner region in the longitudinal direction 5 mm from the elastic layer end of the conductive elastic roller A1 is 1.94, and the electric potential in the region from the inner elastic layer end of the conductive elastic roller 5 mm to 10 mm inward. Unevenness in the circumferential direction of the resistance value was 1.89.

[Evaluation of black streak image]
As an electrophotographic apparatus having the configuration shown in FIG. 6A, a color laser jet printer (trade name “HP Color LaserJet 4700dn” manufactured by Hewlett Packard) is used as an output speed of a recording medium of 200 mm / sec (A4 vertical output). Used after remodeling. The resolution of the image was 600 dpi, and the primary charging output was a DC voltage of −1100V.

  As a process cartridge having the configuration shown in FIG. 6B, the process cartridge for the printer (trade name “print cartridge black Q5950A” manufactured by Hewlett-Packard Company) was used (for black).

  The charging roller was removed from the process cartridge, and the conductive elastic roller A1 of Example 1 was set as the charging roller A1. The charging roller was brought into contact with the photoreceptor with a pressing force of a spring of 4.9 N at one end and a total of 9.8 N at both ends.

  Next, this process cartridge was allowed to stand for 6 hours in an environment of 23 ° C. and 50% RH (relative humidity), then mounted on the electrophotographic apparatus, and evaluated at 23 ° C./50% RH. Specifically, an endurance test for printing a plurality of images with a printing density of 4% (an image in which a horizontal line with a width of 2 dots and an interval of 50 dots is drawn in the direction perpendicular to the rotation direction of the photosensitive member) at a process speed of 200 mm / sec. went. Then, a halftone image (an image in which a horizontal line having a width of 1 dot and an interval of 2 dots is drawn in the direction perpendicular to the rotation direction of the photosensitive member) is output for every 1000 images. About the obtained halftone image, the black streak image was visually observed, and the total number of output images when the black streak occurred was defined as the black streak image generation number.

  The number of black streak images generated in Example 1 was 35,000. Table 5 shows cutting conditions and evaluation results when the conductive elastic roller A1 is manufactured.

[Example 2]
The same procedure as in Example 1 was performed except that the unvulcanized rubber mixture A2 was used, the tension of the cutting wire was 8.0 N, the angular velocity of the inner ring was 13.5 rad / sec, and the angular velocity of the outer ring was 12.0 rad / sec. As a result, a charging roller A2 was obtained. The evaluation results are shown in Table 5.

Example 3
The same procedure as in Example 1 was performed except that the unvulcanized rubber mixture A3 was used and the cutting wire tension was 6.0 N, the inner ring angular velocity was 17.0 rad / sec, and the outer ring angular velocity was 16.1 rad / sec. Thus, a charging roller A3 was obtained. The evaluation results are shown in Table 5.

Example 4
Using the unvulcanized rubber mixture A1, a charging roller A4 was obtained in the same manner as in Example 1 except that the angular velocity of the inner ring was 20.5 rad / sec and the angular velocity of the outer ring was 20.5 rad / sec. The evaluation results are shown in Table 5.

[Comparative Example 1]
A continuous layer 311 of an unvulcanized rubber mixture having a diameter (diameter) of 9 mm was coated on the outer peripheral surface of the shaft core 202 using the unvulcanized rubber mixture B1. No tension is applied to the cutting wire 601 from one outer periphery of the joint portion of the two shaft cores 202 connected in series discharged from the base 305, and the cutting wire 601 is a continuous layer of an unvulcanized rubber mixture. The wire was wound around the continuous layer 311 without entering 311 to form a ring of a cutting wire in which the intersecting portion was in contact with the continuous layer (FIG. 8A). After that, while the rotation of the inner ring 603 and the outer ring 605 is stopped, a tension of 10.0 N is applied to the cutting wire 601 to squeeze the ring of the cutting wire, and the cutting wire is made of the unvulcanized rubber mixture B1. Cut into the continuous layer (FIGS. 8B and 8C) (FIG. 8D). Otherwise, a charging roller B1 was obtained in the same manner as in Example 1. The evaluation results are shown in Table 5.

[Comparative Example 2]
Using the unvulcanized rubber mixture B1, a charging roller B2 was obtained in the same manner as in Example 1 under the production conditions shown in Table 5 using a crosshead extrusion molding apparatus equipped with a cutting machine of the following type. That is, it cut | disconnected using the cutting machine of the type which makes a pair of cutting blade approach the seam of the axial core body 202 from the outer peripheral surface of the continuous layer 311 of unvulcanized rubber mixture B1. The evaluation results are shown in Table 5.

[Comparative Examples 3 to 5]
Charge rollers C1 to C3 were obtained in the same manner as in Comparative Example 1 except that the unvulcanized rubber mixtures A1 to A3 were used. The evaluation results are shown in Table 5.

[Comparative Examples 6-8]
Charge rollers C4 to C6 were obtained in the same manner as Comparative Example 2 except that the unvulcanized rubber mixtures A1 to A3 were used. The evaluation results are shown in Table 5.

202 ··· shaft core 305 ··· base 311 ··· continuous layer 600 of unvulcanized rubber mixture ··· cutting device 601 ··· cutting wire 602 · · · cutting wire supply winding Take-out reel 603 ... Inner ring 604 ... Outer ring 605 ... Inner ring drive gear 606 ... Outer ring drive gear 608 ... Cutting wire guide hole

Claims (1)

A method for producing a conductive elastic roller for electrophotography having a shaft core and a conductive elastic layer covering a peripheral surface thereof,
(1) a step of continuously introducing a plurality of shaft cores in series to the crosshead;
(2) supplying an unvulcanized rubber mixture containing unvulcanized rubber and conductive particles from the extruder connected to the crosshead to the crosshead;
(3) A plurality of shaft cores connected in series and the unvulcanized rubber mixture are co-extruded from the cross head, and the peripheral surfaces of the plurality of shaft cores connected in series are placed on the unvulcanized rubber. Coating with a continuous layer of the mixture;
(4) From one location on the outer periphery of the joint portion of the two axial cores connected in series in the continuous layer, the cutting wire is inserted into the continuous layer while the cutting wire is applied to the continuous layer. Wrapping around the continuous layer, the intersection of the cutting wires enters the continuous layer from a position approximately 180 ° opposite the position where the cutting wire first entered the continuous layer, and the cutting wire The cutting wire is squeezed from the outer peripheral surface of the continuous layer toward the axial core body by squeezing the ring of the cutting wire so that the intersecting portion of the cutting wire and the first contact portion of the cutting wire with the continuous layer approach each other. And a step of cutting the continuous layer by moving the conductive elastic roller.

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