JP4729329B2 - Manufacturing method of conductive roller - Google Patents

Description

  The present invention relates to a method for manufacturing a conductive roller used in an image forming apparatus such as an electrophotographic apparatus such as a copying machine or a printer, or an electrostatic recording apparatus, and in particular, forms a surface layer with high quality by applying a paint. It relates to what can be done.

  Conductive rollers such as a charging roller that is mounted on an image forming apparatus such as an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus and charges the surface of the photosensitive drum, and a developing roller that transfers toner onto the surface of the photosensitive drum Are supported at both ends in the length direction, and a surface layer of a thin film serving as the outermost layer is provided on the outer side in the radial direction of the cylindrical base portion.

  Conventionally, as a method of forming this surface layer, a method of forming a coating film by roll coater coating and using this as a surface layer is proposed in addition to a method of dipping coating or spray coating (see, for example, Patent Document 1). ).

  The roll coater coating method carries the paint supplied from the paint pan on the peripheral surface of the application roll, and connects the conductive roller base portion and the application roll, which are oriented parallel to the application roll, between the peripheral surfaces. This is a method in which the paint is applied simultaneously over the entire length in the length direction of the conductive roller base by rotating it in contact, and it is easy to apply one by one continuously. In contrast, it has the feature of high productivity.

  However, in this method, it is difficult to press the application roll uniformly over the entire length in the length direction of the conductive roller base, so that the thickness of the coating film becomes uneven, and after finishing the coating, When the application roll is detached from the conductive roller, there is a problem that a separation line is generated.

In order to cope with these problems, the application roll is crossed at a predetermined angle with respect to the conductive roller base portion, the peripheral surfaces thereof are brought into contact with each other, and both the application roll and the conductive roller base portion are rotated. A method of forming the surface layer by moving the application roll or the conductive roller base portion in the length direction of the conductive roller base portion and applying the coating on the periphery of the conductive roller base portion in a spiral manner. It has been proposed (see, for example, Patent Document 2).
JP-A-2-261561 Japanese Patent No. 2665795

  According to this proposal, since the peripheral surface of the base portion is applied in a spiral shape, no separation line appears, and instead a step is formed at the boundary of the spiral, but this step reduces the pitch of the spiral. However, because the application roll is a roll with a flat surface, it can be changed due to changes in properties such as the viscosity of the paint and slight changes in application conditions. The film thickness of the paint on the application roll changes, and as a result, the film thickness of the surface layer of the conductive roller varies, and when this method is used for a conductive roller that requires high uniformity, It was difficult to ensure the required surface layer film quality.

  The present invention has been made in view of such problems, and the surface layer does not have a specific nonuniform portion such as a separation line, and the thickness of the surface layer is within one roller or between rollers. It is an object of the present invention to provide a method for producing a conductive roller that can make the thickness uniform.

<1> is a method of manufacturing a conductive roller that is pivotally supported at both ends in the length direction and has a surface layer on the outer side of a cylindrical base portion.
While supplying the paint to the peripheral surface of the gravure roll, the gravure roll and the conductive roller base portion are crossed at a predetermined angle including 90 degrees, and the peripheral surfaces are brought close to each other so that the gravure roll and the conductive roller base portion are While applying a predetermined voltage between the gravure roll and the conductive roller base, rotate the gravure roll and the conductive roller base part at least one of the gravure roll and the conductive roller base part relative to the other in the base part length direction. Thus, the conductive roller is manufactured by applying the paint on the periphery of the conductive roller base portion to form a surface layer.

  <2> is a method for producing a conductive roller according to <1>, wherein a gap of less than 200 μm is provided between the gravure roll peripheral surface and the conductive roller base portion peripheral surface before application, and the relative displacement is performed. is there.

  <3> is a method for producing a conductive roller using <1> or <2>, wherein the paint has a viscosity at 25 ° C. of 500 to 100,000 mP · S.

  <4> is a conductive roller according to any one of <1> to <3>, wherein the paint is made of an electron beam effect resin or an ultraviolet curable resin containing an ultraviolet polymerization initiator. It is a manufacturing method.

  <5> is a method for producing a conductive roller which supplies a paint containing particles having an average particle diameter of 1 to 30 μm to the peripheral surface of the gravure roll in any one of <1> to <4>.

According to the invention of <1>, while supplying the paint to the peripheral surface of the gravure roll, the gravure roll and the conductive roller base portion intersect at a predetermined angle including 90 degrees and bring the peripheral surfaces close to each other. Rotate both the gravure roll and the conductive roller base part, and at least one of the gravure roll and the conductive roller base part is displaced relative to the other to form a surface layer by applying spirally. Therefore, it is possible to form a surface layer without leaving line,
In addition, as the application roll, a gravure roll whose peripheral surface is made of a gravure plate is used, the amount of paint retained on the peripheral surface can be made constant even if the viscosity of the paint slightly changes. By applying a predetermined voltage between the conductive roller base portion and the conductive roller base portion, the paint can be forcibly transferred from the application roll to the conductive roller base portion to stabilize the transfer rate. The thickness of the layer can be made extremely uniform.

  According to the invention <2>, since the gap is provided between the peripheral surface of the gravure roll and the peripheral surface of the conductive roller base before application, the step of the edge of the spiral that occurs when applied spirally is effective. Furthermore, the coating material can be transferred by electrostatic action without contacting the gravure roll and the conductive roller, so that the conductive roller base portion is not damaged. Moreover, the durability of the gravure roll can be improved. In addition, since the gap is less than 200 μm, the rate at which the paint is transferred to the electrostatic force can be stabilized.

  According to the invention of <3>, since a paint having a viscosity of 500 to 100,000 mP · S at 25 ° C. is used as the coating material, the foam in which the base portion has dispersed the void cells by the action of the coating material having a high viscosity and hardly flowing The surface layer can be formed smoothly without filling the void cells exposed on the surface of the substrate portion with the surface layer, while the substrate portion is made of a non-foamed body having no void cells. Even in this case, it is possible to prevent the paint from flowing due to gravity and changing the coating thickness.

  According to the invention <4>, since an electron beam curable resin or an ultraviolet curable resin containing an ultraviolet polymerization initiator is used, the base portion is made of a foam in which void cells are dispersed. In this case, the coating applied with the surface layer is instantaneously cured by electron beam curing or ultraviolet curing, and the surface layer can be smoothly formed without filling the void cells exposed on the surface of the substrate with the surface layer. On the other hand, even when the base portion is made of a non-foamed body without void cells, the coating is instantaneously cured to prevent the coating from flowing due to gravity and changing the coating thickness. it can.

  According to the invention of <5>, since the paint containing particles having an average particle diameter of 1 to 30 μm is supplied to the peripheral surface of the gravure roll, it is transported by the concave portion of the gravure plate formed on the peripheral surface of the gravure roll. The paint can be reliably applied as a surface layer on the periphery of the substrate without changing its particle size distribution, and a desired surface roughness can be achieved by controlling the particle size distribution of the particles in the paint. The degree can be applied to the conductive roller.

The embodiment of the present invention will be described in more detail.
FIG. 1 is a cross-sectional view showing a conductive roller according to the present invention, FIG. 1 (a) shows a first embodiment thereof, and the conductive roller 1 includes a shaft portion 2 supported at both ends in the length direction, and The base portion 3 disposed around the shaft portion 2 and the surface layer 4 covering the peripheral surface of the base portion 3. The shaft portion 2 is made of metal such as iron or stainless steel, or plastic, The base portion 3 is provided so as to protrude outward in the length direction, and the protruding portion is configured to be supported by roller support means of the image forming apparatus.

  FIG. 1B is a cross-sectional view showing a second embodiment of the conductive roller. The conductive roller 1A includes a shaft portion 2A, a base portion 3, and a surface layer 4, and a shaft portion instead of the shaft portion 2. Unlike the first embodiment, the shaft portion 2A is made of a hollow pipe made of a metal such as iron or stainless steel or plastic, and the cross-sectional area of the base portion 3 remains the same outside diameter. When making this smaller, it is possible to make the conductive roller lightweight by suitably using such a hollow shaft portion 2A.

  Further, the shaft portion 2A can be protruded outward in the length direction of the base portion 3, and the outer side in the radial direction can be supported similarly to the shaft portion 2, but as shown in FIG. The surface on the radially inner side of the pipe may be pivotally supported, and in this case, it is not necessary to project the shaft portion 2A outward in the length direction of the base portion 3.

  As the base part 3, a material obtained by adding a conductive agent to a single elastomer or a foam obtained by foaming it is used. The elastomer that can be used here is not particularly limited, and nitrile rubber, ethylene-propylene rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, urethane rubber, acrylic rubber, chloroprene rubber, butyl rubber, An epichlorohydrin rubber etc. are illustrated and these can be used individually or in combination of 2 or more types. Of these, ethylene-propylene rubber, butadiene rubber, silicone rubber, and urethane rubber are preferably used in the present invention. A mixture of these and other rubber materials is also preferably used. In particular, in the present invention, a resin having a urethane bond is preferably used.

  Further, it is also possible to use a foamed product obtained by chemically foaming these elastomers using a foaming agent, or by foaming by mechanically entraining air like polyurethane foam. In the present invention, a so-called RIM molding method may be used in the molding step for integrating the shaft portion 2 and the base portion 3. That is, two types of monomer components constituting the raw material component of the base portion 3 are mixed and injected into a cylindrical mold and polymerized to integrate the shaft portion 2 and the base portion 3. In this method, the molding process from the injection of the raw material to the demolding can be performed in a required time of about 60 seconds, and the production cost can be greatly reduced.

  Various conductive agents can be used as the conductive agent added to the base portion 3. The carbon-based conductive agent can obtain high conductivity with a small amount of addition, and as the carbon-based conductive agent, ketjen black or acetylene black is preferably used, but SAF, ISAF, HAF, FEF, GPF, SRF, Carbon black for rubber such as FT and MT, carbon black for ink such as oxidized carbon black, pyrolytic carbon black, graphite and the like can also be used.

  Examples of ionic conductive agents include dodecyltrimethylammonium such as tetraethylammonium, tetrabutylammonium and lauryltrimethylammonium, octadecyltrimethylammonium such as hexadecyltrimethylammonium and stearyltrimethylammonium, ammonium such as benzyltrimethylammonium and modified aliphatic dimethylethylammonium. Organic ionic conducting agents such as perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, alkylsulfate, carboxylate, sulfonate; Perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, trifluoromethyl sulfate, sulfate of alkali metal or alkaline earth metal such as sodium, calcium, magnesium It can be exemplified inorganic ion conductive agent such as phosphate salts.

  Electronic conductive agents other than carbon-based ones can also be used. Examples of such electronic conductive agents include fine particles of metal oxides such as ITO, tin oxide, titanium oxide, and zinc oxide; nickel, copper, silver, germanium, and the like. Examples thereof include metal oxides; conductive titanium oxide whiskers, transparent whiskers such as conductive barium titanate whiskers; and the like.

  Two or more kinds of conductive agents may be used as a mixture, and in this case, the conductivity can be stably exhibited even when the applied voltage varies or the environment changes. As an example of mixing, a carbon-based conductive agent mixed with an electronic conductive agent other than a carbon-based conductive agent or an ionic conductive agent can be used.

  For example, when the conductive roller 1 is a charging roller, the surface layer 4 is made of nylon, polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, epoxy resin, urethane resin, urea resin, fluorine resin, or the like. However, a fluororesin is preferably used from the viewpoint of the surface smoothness of the charging roller and the low adhesion to the photosensitive member.

  Examples of fluororesins include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, polychlorotriethylene. Fluoroethylene, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, etc. are mentioned. Dispersion type fluororesin is particularly preferably used, and more preferably, polytetrafluoroethylene fine particles are dispersed. Dispersion type fluororesin is used. The particle size of the fluororesin fine particles used is not particularly limited, but is preferably 5 μm or less, and particularly preferably 0.05 to 1 μm.

  Moreover, the surface layer 4 can also be formed by mixing other resins with these fluororesins within a range not impairing the effect of the fluororesin. In this case, examples of other resins mixed with the fluororesin include polyvinyl acetal resin, urethane resin, polyester resin, acrylic resin, nylon resin, epoxy resin, vinylidene chloride copolymer, and the like. Two or more kinds can be mixed with the fluororesin to form the surface layer 4. Among these resins, a polyvinyl acetal resin, a urethane resin, a polyester resin, and a vinylidene chloride copolymer are preferable from the viewpoints of forming a coating film of a fluororesin and uniformity of resistance, and a polyvinyl acetal resin is particularly preferable.

  And as for the above-mentioned acrylic resin, that whose glass transition temperature is -60-20 degreeC, Preferably -50-10 degreeC is used suitably. That is, when the glass transition temperature exceeds 20 ° C., it is possible to form a coating film on the elastic layer 3, but it is easily cracked at the time of charging operation and may not be practically used. On the other hand, glass transition temperatures lower than −60 ° C. have good flexibility but are very sticky and practical due to workability during coating film formation and compatibility with general photoreceptors to be charged. Not very preferable.

  In addition, acrylic resins include thermoplastic types and crosslinking types such as self-crosslinking, melamine crosslinking, and isocyanate crosslinking, and any type is suitable as long as it is within the above glass transition temperature range. Although not particularly limited, a thermoplastic type is particularly preferably used in terms of the coating film forming process and hardness.

  Furthermore, an appropriate amount of an appropriate additive such as a thickener, thixotropic agent, and structural viscosity agent can be added to the surface layer 4 as necessary. In this case, the additive is inorganic. Either an organic type or an organic type may be used.

  When the conductive roller 1 is a developing roller, a crosslinkable resin is preferably used as the resin constituting the surface layer 4. The crosslinkable resin refers to a resin that self-crosslinks with heat, catalyst, air (oxygen), moisture (water), electron beam, or the like, or a resin that crosslinks by reaction with a crosslinking agent or other crosslinkable resin. Examples of such crosslinkable resins include hydroxyl groups, carboxyl groups, acid anhydride groups, amino groups, imino groups, isocyanate groups, methylol groups, alkoxymethyl groups, aldehyde groups, mercapto groups, epoxy groups, unsaturated groups, etc. Fluorine resin, polyamide resin, acrylic urethane resin, alkyd resin, phenol resin, melamine resin, silicone resin, urethane resin, polyester resin, polyvinyl acetal resin, epoxy resin, polyether resin, amino resin, acrylic resin, Mention may be made of urea resins and the like and mixtures thereof. Of these, fluorine resins, polyamide resins, acrylic urethane resins, alkyd resins, phenol resins, melamine resins, silicone resins, urethane resins, polyester resins, polyvinyl acetal resins, epoxy resins, and mixtures thereof are preferred, and alkyd resins are particularly preferred. , Phenol resin, melamine resin and mixtures thereof are preferable from the viewpoint of charging ability of the developer, non-contamination to the developer, reduction of frictional force with other members, non-contamination to the image forming body, and the like.

  For the crosslinkable resin, a catalyst and a crosslinking agent are used as necessary. Examples of the catalyst include radical catalysts such as peroxides and azo compounds, acid catalysts, basic catalysts, and the like. In addition, the crosslinking agent has one molecule of reactive group such as hydroxyl group, carboxyl group, acid anhydride group, amino group, imino group, isocyanate group, methylol group, alkoxymethyl group, aldehyde group, mercapto group, epoxy group, and unsaturated group. A compound having a molecular weight of 1000 or less, preferably a compound having a molecular weight of 500 or less, having two or more compounds therein, includes, for example, a polyol compound, a polyisocyanate compound, a polyaldehyde compound, a polyamine compound, and a polyepoxy compound. This crosslinkable resin can be further charged with a charge control agent, lubricant, conductive agent, other resin, etc. as desired for the purpose of further improving the charging ability to the developer, reducing the frictional force with other members, and imparting conductivity. Various additives can be contained. In the present invention, the resin coating layer is applied at a normal temperature or a temperature of about 50 to 170 ° C. after applying a coating solution in which a crosslinkable resin, a crosslinking agent and various additives are dissolved or dispersed to a roller by a dip coating method. And then cured by cross-linking.

  Among the above resins, those containing an electron beam curable resin or an ultraviolet curable resin are preferable in that a drying step is not required after the surface layer 4 is applied. These resins are irradiated with an electron beam, Alternatively, it can be cured by irradiating with ultraviolet rays in the presence of an ultraviolet polymerization initiator.

  As electron beam curable resin or ultraviolet curable resin, polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, melamine resin, A urea resin, a silicone resin, a polyvinyl butyral resin, etc. are mentioned, These 1 type (s) or 2 or more types can be mixed and used.

  Furthermore, modified resins in which specific functional groups are introduced into these resins can also be used. Further, in order to improve the mechanical strength and environmental resistance characteristics of the resin layer 4, it is preferable to introduce one having a crosslinked structure.

  Among the above-mentioned electron beam curable resins or ultraviolet curable resins, a composition formed from a (meth) acrylate ultraviolet curable resin containing a (meth) acrylate oligomer is particularly suitable.

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

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

  The urethane-based (meth) acrylate oligomer can be obtained by urethanizing a polyol, an isocyanate compound and a (meth) acrylate compound having a hydroxyl group.

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

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

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

  The resin constituting the surface layer 4 is blended with a conductive agent for the purpose of controlling its conductivity. As this conductive material, the same conductive agent contained in the base member 3 as described above is used. Can be used.

Next, a method of forming the surface layer 4 as described above by applying a paint to the outside of the base portion 3 will be described with reference to FIGS. 2 is a plan view showing an apparatus for applying paint, FIG. 3 is a cross-sectional view showing a section corresponding to the arrow AA in FIG. 2, and the application apparatus 20 rotates the conductive roller 1. The roller moving carriage 21 that travels and the coater 10 that supplies and coats the conductive roller 1 with paint is applied. The roller moving carriage 21 supports the conductive roller 1 at both longitudinal ends thereof. The support member 23 includes a motor 24 that rotates the conductive roller 1 at a predetermined number of revolutions, and a travel base 25 on which the support member 23 and the motor 24 are mounted. The travel base 25 is electrically conductive by means (not shown). The reciprocating roller 1 is reciprocated in parallel with the length direction M of the roller 1.
In addition, in the apparatus 1 shown in FIG. 1, the roller moving carriage 21 is configured to reciprocate, but instead, the coater 10 may be reciprocated in the length direction of the conductive roller 1. Alternatively, both may be separated from each other.

  The coater 10 has a tank 12 for containing paint, and a gravure roll 11 and a gravure roll 11 for applying the paint onto the peripheral surface 11a of the conductive roller 1 by pumping the paint from the tank 12 onto the peripheral surface 11a. A support member 13 that rotates, a motor 14 that rotationally drives the gravure roll 11, and a doctor blade 16 that scrapes off excess paint on the peripheral surface 11 a of the gravure roll 11.

  In addition, the coating apparatus 20 includes a voltage application power source 26 that applies a voltage between the gravure roller 11 and the base portion 3 of the conductive roller 1, and the voltage generated by the voltage application power source 26 is a rotating gravure roll 11. The gravure roller 11 is electrically connected to the peripheral surface 11a through a brush (not shown) in contact with both ends in the longitudinal direction and a brush (not shown) in contact with the shaft portion 2 of the rotating conductive roller 1. A predetermined voltage is applied to the peripheral surface of the conductive roller base 3.

  4A and 4B are diagrams showing the gravure roll 11, in which FIG. 4A is a front view, and FIG. 4B is a cross-sectional view corresponding to the arrow BB in FIG. The gravure roll 11 is a roll made of a metal such as iron, and rotates while being pivotally supported at both ends 11b in the length direction. The peripheral surface 11a that draws the paint from the tank 12 and transports it is formed with a concave portion 11c that becomes a gravure plate. Only the paint that is dropped and held in the recess 11c remains. As described above, the transport amount of the paint on the gravure roll 11 is determined by the number of rotations and the total volume of the recess 11c. Therefore, the gravure roll 11 has a higher accuracy than when applied with a flat roll without the recess 11c. Can do.

FIG. 5 is a schematic diagram showing an example of a gravure pattern. The lattice pattern shown in FIG. 5 (a), the pyramid pattern shown in FIG. 5 (b), and the like can be suitably used. For example, when a lattice gravure plate is used, the lattice density is 10 to 10. It is preferable from the viewpoint of uniform coating that 300 / inch, the depth is 20 to 650 μm, and the volume of the recess is 5 to 400 Cm ³ / m ³ .

  In the present invention, when the gravure roller 11 is brought into contact with the base portion 3 of the conductive roller or is applied with a predetermined gap therebetween, the voltage application power source 26 is operated to apply the conductive roller base portion 3. A voltage is applied between the gravure roller 11 and the gravure roller 11. By applying a voltage between them, the transfer amount when transferring the paint held in the concave portion 11c of the gravure roll 11 to the peripheral surface of the base portion 3 is increased and stabilized, and the transport amount of the paint by the gravure roll 11 is made uniform. Due to the synergistic effect with the effect of the above, the coating film thickness of the conductive roller surface layer 4 can be made extremely uniform.

  The applied voltage is 5 to 50 kV and the gap is preferably 200 μm or less. If the voltage is less than 5 kV, the transfer efficiency cannot be sufficiently increased. On the other hand, if this exceeds 50 kV, discharge occurs. . In addition, when the gap exceeds 200 μm, uneven transfer tends to occur.

FIG. 6 is an external view of the conductive roller showing a state in the middle of applying the paint to the base portion 3. When the coating device 20 configured as described above is operated, the paint is applied, and the base portion 3. The spiral coating film 31 is formed on the peripheral surface of the conductive roller 31. The helical pitch P (m) is determined by the feed speed v (m / s) in the roller length direction of the conductive roller base 3. It can be represented by a value obtained by dividing a rotational speed of about omega (s ^-1), the width W of the helix coating 31 by changing the intersection angle θ between the base portion 3 and the gravure roll 11 of the conductive roller 1 changes The width W of the spiral coating 31 can be increased by reducing the crossing angle θ. Then, the rotational speed ω is increased or the feed speed v is decreased to reduce the pitch P of the spiral coating film 31 and the film thickness for one round with respect to the final finished film thickness is decreased. By increasing the width W of the spiral coating 31 with respect to the pitch P of the coating 31, the level difference at the edge 32 of the spiral coating 31 can be reduced, and the surface layer 4 having a smooth and uniform thickness is formed. be able to.

  In order to reduce the amount of step at the spiral edge 32, in addition to the above, a gap is provided between the peripheral surface of the gravure roll 11 and the peripheral surface of the conductive roller base 3 so that the paint can flow naturally. In this case, when the paint on the gravure roll peripheral surface 11a is scraped off by the dokuda blade 16, even if there is a gap, the dokuda blade 16 leaves a paint with a minimum film thickness sufficient to be transferred to the conductive roller. Is preferably set. However, when the gap is 100 μm or more, the paint is transferred from the gravure roll peripheral surface 11a to the peripheral surface of the base portion 3 unless the paint film thickness on the peripheral surface of the gravure roll 11 after being scraped off by the doctor blade 16 is increased. When the coating film thickness on the peripheral surface of the gravure roll 11 is increased, the thickness of the coating film tends to vary.

  Moreover, it is preferable from the surface of uniform coating that the relative rotation direction of the base body portion 3 of the conductive roller 1 and the gravure roll 11 is a direction in which a shearing force is applied to the paint. As illustrated in FIG. It is preferable that the conductive roller tangential direction components of the peripheral surface speed at the portion where the base portion 3 and the gravure roll 11 are in contact with each other or in the vicinity thereof are opposite to each other.

  As a coating applied on the base portion 3 by using the coating apparatus 1, it is possible to use a resin prepared by dissolving the resin exemplified as the resin constituting the surface layer 4 in a solvent or preparing it without a solvent. it can.

  When using a solvent, examples of the solvent used for preparing the coating liquid include alcohol solvents such as methanol, ethanol, isopropanol, and butanol, ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone, and aromatic solvents such as toluene and xylene. Hydrocarbon solvents, aliphatic hydrocarbon solvents such as hexane, alicyclic hydrocarbon solvents such as cyclohexane, ester solvents such as ethyl acetate, ether solvents such as isopropyl ether and tetrahydrofuran, amide systems such as dimethylformamide Examples include solvents, halogenated hydrocarbon solvents such as chloroform and cycloethane, water-based paints such as acrylic paints, and mixed solvents thereof.

  The method of the present invention for forming the surface layer of the conductive roller 1 using the roll coater type coating device 1 is a particularly effective method when using a paint having a viscosity of 500 to 100,000 mP · S at 25 ° C. For example, in the method of forming the surface layer 4 by spraying, it is difficult to atomize such a high-viscosity paint, while the viscosity is too high when formed by immersing the paint contained in the dip tank. This is because the film thickness becomes extremely thick and difficult to realize.

  The advantage of using such a high-viscosity paint is that the paint is difficult to flow, so that the base portion 33 disperses the void cells 34 as shown in the sectional view of the vicinity of the base portion surface in FIG. In the case of being made of a foam, the base portion 33 can be smoothly covered by forming the surface layer 36A having a uniform thickness without filling the void cells 34s exposed on the surface of the base portion 33 with the surface layer 37. If the viscosity of the paint is low, as shown in FIG. 7 (b) corresponding to FIG. 7 (a), the paint flows into the void cell 34s exposed on the surface, and this cell 34s is buried, and the elastic characteristics that the base portion 33 should have and the conductive characteristics that the surface layer 36 should provide cannot be made desirable, and these characteristics become non-uniform.

  In addition, even when the base portion 3 is made of a non-foamed body, the viscosity is high, so that the flow due to gravity can be suppressed and the dimensional change until curing can be suppressed. Can contribute to the formation.

  Similarly, when the surface layer 4 is formed using a paint containing an ultraviolet curable resin or an electron beam curable resin, it is instantly cured immediately after coating, thereby suppressing the flow and increasing the viscosity. The same effect can be brought about. In the first place, the paint containing the ultraviolet curable resin or the electron beam curable resin is used in order to eliminate the large drying equipment required if this is a thermosetting resin. Therefore, in the case of using a paint containing an ultraviolet curable resin or an electron beam curable resin, an extremely low amount of solvent is used. In such a case, for the same reason, a roll coater type is used. The coating method can be suitably used.

  In addition, the method of forming the surface layer 4 using the gravure roll 11 can be used particularly advantageously when the surface layer 4 is a layer in which particles are dispersed. Instead, when a coating liquid is drawn up from a tank using a roll having a flat surface and applied, it is difficult to transport the particles to the base 3 while maintaining a uniform distribution of the particles. By using a gravure roll that can be transported while holding the surface layer, the surface layer 4 having a uniform particle size distribution can be formed.

  For example, when the conductive roller is a developing roller, this particle contributes to enhancing the performance of charging the toner. In this case, as the particle for supporting the performance required for the developing roller. Are preferably fine particles of rubber or synthetic resin or carbon fine particles, specifically silicone rubber, acrylic resin, styrene resin, acrylic / styrene copolymer, fluororesin, urethane elastomer, urethane acrylate, melamine resin, epoxy resin. One or more of phenol resin and silica are preferred.

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

It is sectional drawing which shows the electroconductive roller which concerns on this invention. It is a top view which shows the coating apparatus which forms the surface layer of an electroconductive roller. It is sectional drawing which shows the cross section corresponding to the AA arrow of FIG. It is the top view and sectional drawing which show a gravure roll. It is a schematic diagram of the pattern example of the gravure plate of the gravure roll. It is an external view of the electroconductive roller which shows the state in the middle of applying a coating material to a base | substrate part. It is sectional drawing which shows the surface vicinity of the base | substrate part which consists of foams.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A Conductive roller 2, 2A Shaft part 3, 3A Base part 4, 4A Surface layer 10 Coater 11 Gravure roll 11a Gravure roll peripheral surface 11b Gravure roll both ends 11c Gravure roll concave part 12 Tank 13 Support member 14 Motor 16 Doctor blade 20 Coating device 21 Roller moving carriage 23 Support member 24 Motor 25 Traveling base 26 Voltage application power supply 31 Spiral coating film 32 Spiral coating edge 33 Base portion 34 Void cell 34s Void cell 36, 36A surface layer exposed on the surface

Claims (5)

In a method of manufacturing a conductive roller that is pivotally supported at both ends in the length direction and has a surface layer on the outside of a cylindrical base portion,
While supplying the paint to the peripheral surface of the gravure roll, the gravure roll and the conductive roller base portion are crossed at a predetermined angle including 90 degrees, and the peripheral surfaces are brought close to each other so that the gravure roll and the conductive roller base portion are While applying a predetermined voltage between the gravure roll and the conductive roller base, rotate the gravure roll and the conductive roller base part at least one of the gravure roll and the conductive roller base part relative to the other in the base part length direction. A method of manufacturing a conductive roller, wherein the surface layer is formed by applying the paint on the periphery of the conductive roller base portion.   The method for producing a conductive roller according to claim 1, wherein a gap of less than 200 μm is provided between the gravure roll peripheral surface and the conductive roller base portion peripheral surface before application to perform the relative displacement.   The method for producing a conductive roller according to claim 1 or 2, wherein the paint has a viscosity of 500 to 100,000 mP · S at 25 ° C.   The method for producing a conductive roller according to any one of claims 1 to 3, wherein the paint is made of an electron beam effect resin or an ultraviolet curable resin containing an ultraviolet polymerization initiator. The manufacturing method of the electroconductive roller in any one of Claims 1-4 which supply the coating material containing a particle | grain with an average particle diameter of 1-30 micrometers to the surrounding surface of a gravure roll.

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