JP2005316123A - Conductive roller, its manufacturing method, and cap for masking - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller having a coating layer free of surface defects, and its manufacturing method, and to manufacture a cap for masking appropriate for the same. <P>SOLUTION: The conductive roller has a conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support and the coating layer covering the outer peripheral surface of the elastic layer, wherein both ends in the roller axis direction of the conductive support project from the end surfaces of the elastic layer and constitute the exposed parts of the conductive support. At least one end surface of the elastic layer of the conductive roller exists at the center and the conductive roller has a recessed structure including an annular cavity having the outer periphery of the conductive support as its inner peripheral surface. The cap for masking which has a cylindrical shape having the cavity to permit freely attachable and detachable insertion of the exposed part of the conductive support and has the external diameter at the end serving as an inlet for the cavity smaller than the outer peripheral diameter of the hollow structure at the end surface of the elastic layer is mounted, in an nearly engagement state, into the exposed part of the conductive support on the side having the recessed structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive roller used for development, charging, transfer, fixing, pressurization, cleaning, static elimination, and the like used in an image forming apparatus such as an electrophotography and a copying machine, and a method for manufacturing the conductive roller.

  In recent years, the speed of OA equipment such as copying machines and printers has increased, and in the development process in which the electrostatic latent image on the photoreceptor is visualized with toner, an elastic body is used as a developer carrying member. There has been proposed a contact development method in which development is performed with uniform pressure contact. In this contact development system, the developer carrying member is made of an elastic material in order to ensure a uniform pressure contact width to the photoreceptor, and a voltage is applied to form a toner image on the photoreceptor. Uniform conductivity and leak resistance are required. Therefore, for example, an electronic conductive agent or an ionic conductive agent is dispersed on a conductive support to form an elastic layer adjusted to a desired resistance value, and wear resistance, toner chargeability, and toner transportability are obtained on the outer periphery thereof. Therefore, in many cases, a surface layer is added to a resin such as nylon or urethane to which rough particles for ensuring proper surface roughness and a conductive agent for ensuring conductivity are added. In some cases, a resistance adjusting layer (intermediate layer) is provided between the elastic layer and the surface layer in order to stabilize the resistance of the developer carrying member.

  In the case of the contact development method, the surface of the outermost layer of the developer carrying member is required to be a uniform surface because it contacts the toner or the photoreceptor. For example, when a film thickness unevenness (coating unevenness), bubbles, or streaks are observed on the surface layer, this mark appears as an image defect.

  Generally, coating (coating) is used as a method for producing a surface layer provided in order to obtain wear resistance, toner chargeability, and toner transportability. Specifically, dip coating, roll coating, spray coating, and other methods are used to form a film of several microns to several tens of microns. Among them, dip coating is excellent for forming a uniform coating layer. Often used.

  At that time, it is common to perform masking in a place where the paint is not desired to be adhered. Speaking of the normal masking method, if the object to be coated is like a sheet metal, a sheet is applied to prevent contamination, and if it is like a roller, the shaft end is covered with a tube or cap for coating. Is taken.

  Conventionally, when a coating layer is formed on a roller using a coating liquid, the conductive support is used to prevent coating layer surface defects, coating unevenness at the end of the roller, and adhesion of the coating liquid to the conductive support. It is a common method to attach a masking member in the shape of a tube or cap to the top.

  For example, in patent document 1, in order to solve the said problem, a masking tube is adhere | attached on an electroconductive support body. According to this, during coating or drying, air that is slightly present between the masking tube and the conductive support or between the masking tube and the elastic body end oozes out into the coating on the end of the roller and bubbles. It is described that the problem that pinholes are easily generated in this portion and the coating layer is easily cut off is solved.

  However, when a tube-shaped masking cap is used in dip coating in which the roller is immersed in the coating solution in a vertical state, defects are generated on the surface of the coating layer. Specifically, when a roller with a tube-shaped masking cap is lowered into the coating liquid in a vertical state, the coating liquid does not enter the hollow portion at the center of the tube, and air is collected. When the roller descends and time elapses, volatile gas in the paint is added to the air accumulated in the center of the tube. Further, when the roller starts to rise, the hydraulic pressure applied to the gas in the cavity portion becomes smaller as the roller rises, so that the gas expands in volume and finally bubbles are generated. Another method of generating bubbles is that if there is a gap between the masking tube and the conductive support, or between the masking tube and the roller end, the roller is lowered into the coating liquid in a vertical state. As it goes, air that is slightly present in the gap oozes out due to hydraulic pressure and generates bubbles.

  Bubbles generated in the above manner rise to the coating liquid surface, but may adhere to the roller side due to the surface tension between the roller and the liquid surface. Further, since the roller descends and ascends, the bubbles are rubbed against the surface of the roller with the liquid surface, and this trace remains as a streak-like concave defect in the longitudinal direction of the roller even after drying.

As measures to prevent defects due to bubbles, there are a method of slowing the liquid surface penetration speed of the roller and a method of adding an antifoaming agent such as silicone oil in the coating liquid. The time is increased, and the additive is not satisfactory because there are harmful effects on the coating solution and the product.
JP 10-177290 A (page 5)

  As described above, normally, bringing air into the coating liquid during dip coating directly leads to a surface defect of the roller and a defective image. Therefore, it is an effective method for obtaining a uniform coating layer to prevent air from being brought into the coating solution during coating. However, depending on the shape of the roller before coating, there are some rollers that are difficult to apply without bringing air into the coating solution. In such a case, the shape of the masking cap can be devised to prevent air from being introduced into the coating solution. It is difficult to eliminate them completely.

  An object of the present invention is to provide a conductive roller having a coating layer free from surface defects, a method for producing the same, and a masking cap suitable for the conductive roller.

The present invention achieves the object by the following.
[1] A conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer, the conductive support In the method for manufacturing a conductive roller, both ends in the roller axial direction of the elastic layer protrude from the end face of the elastic layer to form a conductive support exposed portion.
(A) On the outer periphery of the conductive support,
Forming at least one end surface an elastic layer having a concave structure including a ring-shaped cavity with the conductive support located in the center and the outer periphery of the conductive support as an inner peripheral surface;
(B) In the conductive support exposed portion on the side having the concave structure,
For the masking, which has a cylindrical shape having a hollow portion into which the conductive support exposed portion can be detachably inserted, and an outer diameter of an end portion serving as an inlet of the hollow portion is smaller than an outer diameter of the concave structure Attaching the cap in a substantially fitted state;
(C) A step of immersing the elastic body in the coating liquid for forming the coating layer with the side on which the masking cap is mounted facing down, and coating the outer peripheral surface of the elastic layer with the coating liquid When,
(D) A method for producing a conductive roller, comprising: drying the coating liquid on the outer peripheral surface of the elastic layer to form a coating layer.
[2] A conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer, In the conductive roller in which both ends in the roller axial direction protrude from the end face of the elastic layer to form a conductive support exposed portion,
At least one end face of the elastic layer has a concave structure including a ring-shaped cavity in which the conductive support is located in the center and the outer periphery of the conductive support is an inner peripheral surface. Sex roller.
[3] A conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer, A conductive roller having both ends in the roller axial direction projecting from the end face of the elastic layer to form a conductive support exposed portion, wherein at least one end face of the elastic layer is located at the center of the conductive support and In order to mount the conductive roller having a concave structure including a ring-shaped cavity with the outer periphery of the conductive support as an inner peripheral surface to the conductive support exposed portion on the side having the concave structure in a substantially fitted state. In the masking cap of
The conductive support exposed portion has a cylindrical shape having a cavity into which the removable portion can be detachably inserted, and the outer diameter of the end serving as the inlet of the cavity is the outer diameter of the concave structure on the end surface of the elastic layer Masking cap, characterized in that it is smaller.

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive roller which has a coating layer without a surface defect, its manufacturing method, and the masking cap suitable for it can be provided.

(1) Conductive roller and manufacturing method thereof The present invention relates to a conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer And a conductive roller manufacturing method in which both ends in the roller axial direction of the conductive support protrude from the end face of the elastic layer to form a conductive support exposed portion.
(A) On the outer periphery of the conductive support,
Forming at least one end surface an elastic layer having a concave structure including a ring-shaped cavity with the conductive support located in the center and the outer periphery of the conductive support as an inner peripheral surface;
(B) In the conductive support exposed portion on the side having the concave structure,
For the masking, which has a cylindrical shape having a hollow portion into which the conductive support exposed portion can be detachably inserted, and an outer diameter of an end portion serving as an inlet of the hollow portion is smaller than an outer diameter of the concave structure Attaching the cap in a substantially fitted state;
(C) A step of immersing the elastic body in the coating liquid for forming the coating layer with the side on which the masking cap is mounted facing down, and coating the outer peripheral surface of the elastic layer with the coating liquid When,
(D) A method for producing a conductive roller, comprising the step of drying the coating liquid on the outer peripheral surface of the elastic layer to form a coating layer.

Further, the conductive roller can be preferably manufactured by this method. That is, a conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer, the roller of the conductive support In the conductive roller in which both ends in the axial direction protrude from the end surface of the elastic layer to form a conductive support exposed portion,
At least one end face of the elastic layer has a concave structure including a ring-shaped cavity in which the conductive support is located in the center and the outer periphery of the conductive support is an inner peripheral surface. It is a sex roller.

  First, (A) at least one end surface of the outer periphery of the conductive support includes a ring-shaped cavity having the conductive support at the center and the outer periphery of the conductive support as an inner peripheral surface. An elastic layer having a concave structure is formed.

  1 and 2, as one embodiment of the present invention, a cross-sectional view of an elastic layer formed on the outer periphery of a conductive support (FIG. 1: a cross-sectional view perpendicular to the axial direction of the conductive support, FIG. 1 is a sectional view parallel to the axial direction of a conductive support. In this example, ring-shaped depressions are present on both end faces of the elastic layer so as to surround the conductive support. Thus, in the present invention, at least one end surface of the elastic layer has a concave structure including a ring-shaped cavity in which the conductive support is located in the center and the outer periphery of the conductive support is the inner peripheral surface. Is a feature.

  As the conductive support a as the roller shaft, a round bar made of a metal material such as iron, copper, and stainless steel can be used. Further, these metal surfaces may be plated for the purpose of providing rust prevention and scratch resistance. Although there is no restriction | limiting in particular in the outer diameter of an electroconductive support body, Usually a 4-20 mm thing is used.

  Examples of the resin material for forming the elastic layer b include natural rubber, ethylene propylene rubber (EPDM), styrene butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), and butadiene rubber (BR). , Nitrile butadiene rubber (NBR), and synthetic rubber such as chloroprene rubber (CR), and further, polyamide resin, polyurethane resin, and silicone resin. Silicone rubber and urethane rubber are preferable. A conductive agent having an electron conduction mechanism such as carbon black, graphite, and a conductive metal oxide and a conductive agent having an ion conduction mechanism such as an alkali metal salt or a quaternary ammonium salt are appropriately added to these materials to obtain a desired resistance. It can be adjusted to use. The elastic layer may be a single layer or may have a multilayer structure of two or more layers.

  There is no restriction | limiting in particular as a formation method of the elastic layer b. For example, in the case of the casting method, the concave structure as described above can be formed on at least one end face by setting the shape of the mold to a corresponding shape. A masking cap, which will be described later, is attached to the concave structure portion.

  The width of the ring forming the concave structure is preferably 1 to 5 mm, and the depth of the concave structure is preferably 2 to 6 mm.

  Next, (B) the conductive support exposed portion on the side having the concave structure has a cylindrical shape having a hollow portion into which the conductive support exposed portion can be detachably inserted. A masking cap having an outer diameter at an end serving as an inlet of the lip is smaller than an outer diameter of the concave structure is fitted in a substantially fitted state. That is, the masking cap is attached to the conductive support exposed portion on the side having the concave structure so that the coating liquid does not adhere to the conductive support when immersed in the coating liquid in the next step. The structure of the masking cap will be described in detail separately. However, it is important that a ring-shaped concave structure still exists on the end face of the elastic layer with the masking cap attached (FIGS. 3 to 6). reference).

  Then, (C) the elastic body is immersed in the coating liquid for forming the coating layer with the masking cap attached side down, and the outer peripheral surface of the elastic layer is coated with the coating liquid. Then, (D) the coating liquid on the outer peripheral surface of the elastic layer is dried to form a coating layer.

  Examples of the resin material for forming the coating layer (surface layer) include fluorine resin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene-butylene-olefin copolymer (SEBC), and olefin- And ethylene / butylene-olefin copolymer (CEBC). A polyurethane resin is preferred. In order to reduce the static friction coefficient, solid lubricants such as graphite, mica, molybdenum disulfide, and fluororesin powder, or a fluorosurfactant, wax, or silicone oil can be added to these resin materials. In order to make the coating layer conductive, various conductive agents (conductive carbon, graphite, copper, aluminum, nickel, iron powder and metal oxides such as conductive tin oxide and conductive titanium) are added. You can also Further, in order to obtain wear resistance and toner transportability, rough particles are often added, and the rough particles are preferably spherical resin particles made of a material such as polymethyl methacrylate, polystyrene, or polyurethane. Can be used.

  A coating solution is prepared by dissolving the components for forming the coating layer as described above in a solvent. There is no restriction | limiting in particular as a solvent, Water and / or various organic solvents can be used. Examples of the organic solvent include toluene, xylene, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, and the like. At this time, when coarse particles are added, selection may be made as appropriate so that the coarse particles are not swelled or dissolved by the solvent used. The usage-amount of a solvent can be suitably adjusted so that it may become the viscosity which can be applied to the elastic body surface. Usually, the viscosity of the coating liquid is preferably in the range of 1 to 250 mPa · s. However, since the viscosity greatly affects the film thickness, it is particularly preferable to adjust the viscosity in the range of 5 to 25 mPa · s.

  In this coating solution, the elastic body is immersed with the side on which the masking cap is attached facing down, and the outer peripheral surface of the elastic layer is covered with the coating solution. An example of this state is shown in FIG. At this time, a ring-shaped concave structure still exists on the end face of the elastic layer.

  Normally, when bubbles are generated in the coating liquid in this coating process, streaky concave defects are generated in the coating layer due to the influence of the bubbles. Therefore, according to the conventional technique, it is preferable not to bring air into the coating liquid at the time of immersion. However, it is very difficult not to bring air into the coating liquid. Even if the cap shape fills the dent on the end face of the elastic layer, in most cases, fine bubbles are bitten during immersion due to the slight gap between the elastic layer and the cap. On the other hand, in the present invention, even when the masking cap is attached, a ring-shaped concave structure still exists on the end face of the elastic layer. Therefore, when immersed in the coating liquid, air that is ring-shaped exists in the concave structure portion of the end face of the elastic layer. The air exists in a ring shape around the masking cap, so that it can be stably present in the coating liquid unlike the fine bubbles. That is, no streak-like concave defect occurs in the coating layer.

  The entry speed of the elastic layer into the coating solution is preferably 2 to 50 mm / s, and more preferably 2 to 30 mm / s. In particular, when the speed of entering the liquid surface is too high, the ring-shaped air is likely to flow away, and bubbles are easily involved when the masking cap and the elastic layer end enter the liquid surface.

  When dipping, the coating liquid is preferably in a state that does not flow. However, when the coating liquid contains insoluble components such as a conductive agent and rough particles, when the coating liquid is applied statically, streaks are not formed on the coating surface formed on the elastic layer. As long as the ring-shaped air is present stably, it may flow at an appropriate flow rate. However, since it becomes difficult for the ring-shaped air to exist stably when turbulent flow occurs, it is preferably a laminar flow.

  It is also possible to immerse the whole by attaching a masking cap to the upper conductive support exposed portion. At this time, there is no limitation on the masking cap attached to the upper conductive support exposed portion, and the same masking cap attached to the lower conductive support exposed portion may be used. A conventionally known masking cap may be used.

  The drying conditions performed after coating the coating solution by the immersion can be appropriately set according to the composition of the coating solution used. Depending on the type of resin material, the curing treatment can be performed under suitable conditions after drying or simultaneously with drying. The coating layer may be a single layer or may have a multilayer structure of two or more layers, and the coating layer having a multilayer structure can be formed by repeating the steps (C) and (D).

  According to the method of the present invention as described above, it is possible to manufacture a conductive roller having a uniform coating layer free from surface defects and causing no image defects.

(2) Masking cap The masking cap of the present invention is
A conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer, the roller axis direction of the conductive support A conductive roller in which both ends of the elastic layer protrude from the end surface of the elastic layer to form an exposed portion of the conductive support, and at least one end surface of the elastic layer has the conductive support positioned at the center and the conductive layer Masking for mounting a conductive roller having a concave structure including a ring-shaped cavity with the outer periphery of the support body as an inner peripheral surface in a substantially fitted state to the conductive support exposed part on the side having the concave structure In the cap,
The conductive support exposed portion has a cylindrical shape having a cavity into which the removable portion can be detachably inserted, and the outer diameter of the end serving as the inlet of the cavity is the outer diameter of the concave structure on the end surface of the elastic layer It is the cap for masking characterized by being smaller than this. By using such a masking cap when the elastic layer is immersed in the coating liquid for forming the coating layer, streak-like concave defects are not generated in the coating layer during the immersion.

  The material of the masking cap is not particularly limited as long as it does not contaminate the coating liquid and does not corrode by the coating liquid. Examples include polyethylene, polypropylene, polyamide, fluorine resin, methylpentene resin, phenol resin, melamine resin, and polyacetal resin. Preferred are polyethylene, polypropylene, fluorine resin, and polyacetal resin. Further, as a condition for determining the material for the masking cap, it is preferable to select a material that can provide high dimensional accuracy when the masking cap is formed.

  In the masking cap of the present invention, the outer diameter of the end portion serving as the entrance of the hollow portion into which the conductive support exposed portion is inserted is smaller than the outer peripheral diameter of the concave structure on the end surface of the elastic layer. Therefore, even when the masking cap is attached to the exposed portion of the conductive support in a substantially fitted state, a concave structure still exists on the end face of the elastic layer. The width of the ring-shaped concave structure present on the end face of the elastic layer in a state where the masking cap is mounted in the substantially fitted state on the conductive support exposed portion is preferably 1 to 5 mm. The outer diameter of the masking cap only needs to satisfy at least the depth of the concave structure formed on the end face of the elastic layer. For example, the conductive support exposed portion of the masking cap The outer diameter of the masking cap is not particularly limited near the end opposite to the entrance of the cavity to be inserted.

  The end of the conventionally known masking cap opposite to the entrance of the cavity where the conductive support exposed part is inserted is perpendicular to the axial direction of the conductive support (that is, the level of the coating liquid to be immersed) Therefore, when the mask is lowered with the masking cap attached, the liquid level is greatly disturbed when entering the liquid level, and bubbles are often generated. In addition, even when a tube-shaped masking cap is attached, the coating liquid does not accumulate in the hollow portion in the center of the tube but air accumulates, and solvent gas is added thereto to expand the volume and generate bubbles. This air and solvent gas are present in the coating liquid in a spherical shape protruding from the tip of the masking tube, so it is very unstable in the liquid and is likely to float to the liquid surface while the roller is descending and rising. This bubble increases the possibility of pinholes and streak-like concave defects in the longitudinal direction of the roller.

  Therefore, it is preferable that the masking cap of the present invention has a streamline shape with no end hole on the side opposite to the inlet of the cavity into which the conductive support exposed portion is inserted. Examples of streamline shapes include conical shapes (see FIGS. 3 and 4) and hemispherical shapes (FIGS. 5 and 6). By doing so, the disturbance of the liquid level when entering the liquid level is small and bubbles are not generated, and since there is no hole, bubbles are not generated even during roller immersion.

  The masking cap according to the present invention has a cylindrical shape having a hollow portion into which the conductive support exposed portion can be detachably inserted in order to be attached to the conductive support exposed portion in a substantially fitted state. Yes. It is preferable that the inner diameter of the hollow portion is a diameter that is substantially fitted to the exposed portion of the conductive support. Specifically, it is preferably within a range of ± 0.05 mm, more preferably within a range of ± 0.02 mm with respect to the outer diameter of the conductive support.

  Further, the cavity of the masking cap has three or more protrusion structures (gates) that can hold the conductive support and have three or more protrusion structures parallel to the longitudinal direction of the cavity. Is preferred. For example, as shown in a sectional view and a plan view in FIG. 10, the inner cylinder portion 100 that forms the cavity portion 10 to which the conductive support exposed portion can be attached and detached, and an inner diameter larger than the outer diameter of the inner cylinder portion. It is preferable that the masking cap 1 has an outer cylinder portion 101. The inner cylinder part 100 is provided from the bottom part of the outer cylinder part 101 toward the opening direction, and has a shape divided into three by three slits 103 extending from the bottom part of the outer cylinder part 101 in the opening direction. . As a result, when the masking cap is attached to the exposed portion of the conductive support, a gap is formed between the exposed portion of the conductive support and the cavity of the masking cap, so an air escape path is secured and the masking cap is smooth. It can be attached to the exposed portion of the conductive support. When the tip of the protruding structure is the inner diameter of the cavity of the masking cap, it is preferably within ± 0.05 mm, more preferably within ± 0.02 mm with respect to the outer diameter of the conductive support. It is preferable that

  The masking cap of the present invention as described above can be suitably used for production of a conductive roller having a uniform coating layer free from surface defects and causing no image defects.

  Hereinafter, the present invention will be described in more detail using specific examples.

Example 1
A developing roller was produced in the following manner.

-Formation of elastic layer An iron shaft (conductive support) with an outer diameter of φ8 mm is placed concentrically in a cylindrical mold with an inner diameter of φ16 mm, and liquid conductive silicone rubber (Toray Dow) is used as a material for forming the elastic layer. Corning Co., Ltd., volume resistivity 10 ⁷ Ωcm product) is cast, placed in an oven at 130 ° C., heat-molded for 20 minutes, demolded, and subjected to secondary vulcanization in an oven at 200 ° C. for 4 hours. An elastic layer having a length of 240 mm was formed. At this time, a mold having an inner diameter of 12 mm and a depth of 2 mm is formed on both end faces of the elastic body so that the outer periphery of the iron shaft is formed in a ring shape that becomes the inner peripheral surface. An elastic layer having a depression was formed.

・ Preparation of coating liquid for coating layer Urethane paint (trade name: Nipponporan N5033, manufactured by Nippon Polyurethane Co., Ltd.) is diluted with methyl ethyl ketone so that the solid content concentration is 10% by mass, and carbon black (trade name: # 7360SB) is used as a conductive agent. , Manufactured by Tokai Carbon Co., Ltd., with an average particle size of 28 nm), 50 parts by weight of urethane paint solid content of 100 parts by weight, and urethane particles having a mean particle size of 14 μm as insulating particles (trade name: Art Pearl C400, manufactured by Negami Kogyo Co., Ltd.) After adding 6 parts by mass with respect to 100 parts by mass of solid content, 10 parts by mass of a curing agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) is added to 100 parts by mass of urethane paint solids. Further, the mixture was stirred to obtain a coating layer coating solution. The viscosity of the coating layer coating liquid at this time was 15 mPa · s.

・ Formation of coating layer (coating of coating liquid for coating layer)
One of the iron shafts (conductive support) was covered with a masking cap c made of polyacetal having a cylindrical shape with an outer diameter of φ9 mm and a hollow portion with an inner diameter of φ8.02 mm. The masking cap has a conical shape on the side opposite to the entrance of the cavity (see FIG. 3). Next, with this masking cap on the lower side, hold it perpendicular to the tank containing the coating layer coating solution, and then drop it straight down and immerse it toward the liquid level. Raised. The descent speed was 20 mm / s, the immersion time was 5 s, and the lifting speed was 3 mm / s. Thereafter, the masking cap was removed, and a coating layer was formed through steps of air drying and heat curing (150 ° C., 1 h) to obtain a developing roller.

  Ten developing rollers were produced by the above method, and the presence or absence of defects on the surface of the obtained developing roller (that is, on the coating layer formed on the elastic layer) was examined. The results are shown in Table 1.

(Example 2)
Example 1 except that a masking cap having an outer diameter opposite to the entrance of the cavity portion of φ16 mm, which is the same as the roller diameter, has a conical shape (see FIG. 4). A developing roller was prepared in the same manner as above, and the presence or absence of defects was similarly examined. The results are shown in Table 1.

(Example 3)
A developing roller was prepared in the same manner as in Example 1 except that a masking cap having a hemispherical tip (see FIG. 5) opposite to the inlet of the cavity was used. I investigated. The results are shown in Table 1.

Example 4
As the masking cap, the same as in Example 1 except that the outer diameter opposite to the entrance of the cavity is φ16 mm, which is the same as the roller diameter, and the tip of the cap is hemispherical (see FIG. 6). A developing roller was prepared, and the presence or absence of defects was similarly examined. The results are shown in Table 1.

(Comparative Example 1)
Except for using a masking cap having an outer diameter of φ12 mm at the end serving as the entrance to the cavity and a conical tip on the opposite side (see FIG. 7), the same as in Example 1. A developing roller was prepared, and the presence or absence of defects was similarly examined. The results are shown in Table 1.

(Comparative Example 2)
As a masking cap, the shape of the end that becomes the entrance of the cavity is a shape that can completely cover the end face of the elastic layer, and the tip on the opposite side has a conical shape (see FIG. A developing roller was produced in the same manner as in Example 1 except that the above was used, and the presence or absence of defects was similarly examined. The results are shown in Table 1.

  Examples 1 to 4 are states according to the present invention, in which ring-shaped air is included between the concave portion of the end face of the elastic body and the masking cap. As a preliminary experiment, the state of bubbles in the vicinity of the masking cap during immersion in the roller was observed with a transparent liquid having a viscosity of 15 mPa · s as in this example, and ring-shaped air was present around the masking cap. It was confirmed. Under these conditions, bubbles did not rise to the liquid surface, and a uniform surface free from defects could be obtained. Also, since the coating layer on the surface of the elastic layer and the coating layer on the masking cap are discontinuous surfaces, when removing the masking cap, the coating layer at the end of the elastic layer is pulled regardless of the drying time of the coating layer. The phenomenon of peeling off the coating layer at the end of the elastic layer did not occur.

  On the other hand, in Comparative Examples 1 and 2, it is confirmed that bubbles rise to the liquid surface at the moment when the interface between the elastic body and the masking cap sinks in the coating liquid, and when the roller moves up and down. The bubbles adhered to the coating liquid portion on the elastic layer and rubbed on the surface, and the trace remained as a streak-like concave defect in the longitudinal direction even after drying. Furthermore, in Comparative Example 2, when the masking cap was removed, the paint at the end of the elastic layer was pulled, and the paint burrs and the elastic layer were exposed.

It is sectional drawing perpendicular | vertical to the axial direction of a conductive support body although the elastic layer was formed in the outer periphery of a conductive support body. It is sectional drawing parallel to the axial direction of a conductive support, although the elastic layer was formed in the outer periphery of a conductive support. FIG. 3 is a partially enlarged cross-sectional view when a masking cap is mounted in Example 1. FIG. 6 is a partially enlarged cross-sectional view when a masking cap is mounted in Example 2. 6 is a partial enlarged cross-sectional view when a masking cap is mounted in Example 3. FIG. FIG. 6 is a partially enlarged cross-sectional view when a masking cap is mounted in Example 4. 6 is a partially enlarged cross-sectional view when a masking cap is attached in Comparative Example 1. FIG. 6 is a partially enlarged cross-sectional view when a masking cap is attached in Comparative Example 2. FIG. It is a figure which shows the state which has immersed the elastic body in the coating liquid for forming a coating layer with the side in which the masking cap was mounted | worn down. It is a figure which shows the structure of the preferable cap for masking, (a) is sectional drawing along an axial direction, (b) is the top view seen from the opening side.

Explanation of symbols

a: conductive support b: elastic layer c: masking cap d: coating liquid for coating layer 1: masking cap 10: cavity 100: inner cylinder 101: outer cylinder 103: slit

Claims (5)

A conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer, the roller shaft of the conductive support In the manufacturing method of the conductive roller in which both ends in the direction protrude from the end surface of the elastic layer to form the conductive support exposed portion,
(A) On the outer periphery of the conductive support,
Forming at least one end surface an elastic layer having a concave structure including a ring-shaped cavity with the conductive support located in the center and the outer periphery of the conductive support as an inner peripheral surface;
(B) In the conductive support exposed portion on the side having the concave structure,
For the masking, which has a cylindrical shape having a hollow portion into which the conductive support exposed portion can be detachably inserted, and an outer diameter of an end portion serving as an inlet of the hollow portion is smaller than an outer diameter of the concave structure Attaching the cap in a substantially fitted state;
(C) A step of immersing the elastic body in the coating liquid for forming the coating layer with the side on which the masking cap is mounted facing down, and coating the outer peripheral surface of the elastic layer with the coating liquid When,
(D) A method for producing a conductive roller, comprising: drying the coating liquid on the outer peripheral surface of the elastic layer to form a coating layer. A conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer, the roller axis direction of the conductive support In the conductive roller in which both ends protrude from the end surface of the elastic layer to form a conductive support exposed portion,
At least one end face of the elastic layer has a concave structure including a ring-shaped cavity in which the conductive support is located in the center and the outer periphery of the conductive support is an inner peripheral surface. Sex roller. A conductive support as a roller shaft, an elastic layer formed on the outer periphery of the conductive support, and a coating layer covering the outer peripheral surface of the elastic layer, the roller axis direction of the conductive support A conductive roller in which both ends of the elastic layer protrude from the end surface of the elastic layer to form an exposed portion of the conductive support, and at least one end surface of the elastic layer has the conductive support positioned at the center and the conductive layer Masking for mounting a conductive roller having a concave structure including a ring-shaped cavity with the outer periphery of the support body as an inner peripheral surface in a substantially fitted state to the conductive support exposed part on the side having the concave structure In the cap,
The conductive support exposed portion has a cylindrical shape having a cavity into which the removable portion can be detachably inserted, and the outer diameter of the end serving as the inlet of the cavity is the outer diameter of the concave structure on the end surface of the elastic layer Masking cap, characterized in that it is smaller.   The masking cap according to claim 3, wherein an end surface of the hollow portion opposite to the inlet has no hole and has a streamline shape. Inside the cavity,
5. The masking cap according to claim 3, wherein the masking cap is capable of holding the conductive support and has three or more protrusion structures parallel to the longitudinal direction of the hollow portion.

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