JP2006317688A - Method for manufacturing conductive roller, coating device for conductive roller, and conductive roller formed by the manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a conductive roller and a coating device for a conductive roller by which a surface layer of a conductive roller can be formed by spraying a solvent-free coating material or a coating material having a small amount of solvent so as to eliminate or simplify a drying process, and to provide a conductive roller formed by the above manufacturing method. <P>SOLUTION: The method for manufacturing a conductive roller includes the step of spraying a coating material to form a surface layer 4, and prior to spraying the coating material, the step of increasing the temperature of both of the coating material and a compressed gas which atomizes the coating material so as to control the viscosity of the coating material to 1 to 1,000 mPa S. A coating material containing a UV-curing resin or an electron beam curing resin is used for the coating material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a conductive roller used in an electrophotographic apparatus such as a copying machine and a printer, and an image forming apparatus such as an electrostatic recording apparatus, and a conductive roller formed by this method. The present invention relates to a material that can be applied to form a surface layer efficiently and with high accuracy.

  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 the surface layer of such a conductive roller, a method of forming a coating film by spray coating and using this as a surface layer is proposed in addition to a method of dipping coating or roll coater coating ( For example, refer to Patent Document 1.)
Japanese Patent Laid-Open No. 9-179378

  In this spray coating method, while rotating the conductive roller, the spray gun is displaced in the length direction of the conductive roller, and the surface layer is formed by spraying paint on the outside of the base portion. Compared with the method, the thin film layer can be formed with high precision, and there is no need for a tank or paint tank for storing a large amount of paint, so that it is not necessary to produce a large lot. It has the feature that it is suitable for production forms of small quantities.

  However, when it is intended to form the surface layer of the conductive roller using this method, it is necessary to lower the viscosity of the paint in order to atomize the paint. Therefore, the surface layer forming material is usually used as the paint. A solution diluted with a solvent to lower the viscosity is used. And the amount of the solvent is increased as the viscosity of the surface layer forming material is higher. On the other hand, a paint diluted with a solvent in this manner requires a drying process for vaporizing the solvent after the coating, and a drying line for this purpose, a space for installing this line, and further for drying. A heat source is required. In particular, when a paint diluted with a large amount of solvent is used, there is a problem that the cost and space for that purpose are enormous. Furthermore, the lengthening of the drying process has a problem that the thickness of the surface layer becomes nonuniform due to the flow of the coating film during drying.

  The present invention has been made in view of such problems, and in order to eliminate or simplify the drying process, the surface layer of the conductive roller is formed by spraying a solvent-free or small amount of solvent paint. It is an object of the present invention to provide a conductive roller manufacturing method, a conductive roller coating apparatus, and a conductive roller formed by this manufacturing method.

  <1> forms a surface layer by spraying the paint atomized by the compressed gas on the peripheral surface of the columnar base portion provided outside the shaft portion supported at both ends in the length direction. In the method for producing a conductive roller, the temperature of both the paint and the compressed gas is increased so that the viscosity of the paint becomes 1 to 1000 mPa · S.

  <2> is a method for producing a conductive roller using <1> that contains an ultraviolet curable resin or an electron beam curable resin as a coating material.

  <3> is the length of the base part with respect to the spray gun for spraying paint and at least one of the base part with respect to the other in the state where the base part is rotated around the shaft part in <1> or <2> This is a method for manufacturing a conductive roller that sprays paint while being relatively displaced in the vertical direction.

<4> forms a surface layer by spraying the paint atomized by the compressed gas on the peripheral surface of the columnar base portion provided outside the shaft portion pivotally supported at both ends in the length direction. A conductive roller coating apparatus used in a method of manufacturing a conductive roller,
Spray gun for spraying paint, paint tank for containing paint, paint supply pipe for transporting paint from paint tank to spray gun, gas reservoir for storing compressed gas, and gas for supplying compressed gas from gas reservoir to spray gun The gas stored in the gas reservoir is provided with at least one of a tank heating device that includes a supply pipe and raises the temperature of the paint contained in the paint tank and a pipe heating device that raises the temperature of the paint passing through the paint supply pipe. And a gas heating device that heats at least one of the gas passing through the gas supply pipe.

  <5> is a conductive roller coating device provided with a paint return pipe that bypasses the spray gun and returns the paint supplied from the paint tank via the paint supply pipe to the paint tank in <4>.

  <6> includes a shaft portion that is pivotally supported at both ends in the length direction, a base portion disposed around the shaft portion, and a surface layer that covers the peripheral surface of the base portion. , <1> to <3>, a conductive roller formed by the method for manufacturing a conductive roller.

  According to the invention of <1>, prior to spraying the paint, both the paint and the compressed gas are heated so that the viscosity of the paint is 1 to 1000 mPa · s. Even so, the paint can be atomized in good condition, and as a result, the drying line can be simplified or eliminated, saving the cost and space it took, In addition, the problem of non-uniform surface layer thickness due to the flow of paint during the drying process can be solved.

  When the viscosity of the paint is less than 1 mPa · S, the paint particles in the paint atomization become too fine and the coating efficiency deteriorates. On the other hand, when the viscosity exceeds 1000 mPa · S, the paint becomes difficult to atomize. The uniformity of the film is deteriorated.

  According to the invention of <2>, since a coating containing an ultraviolet curable resin or an electron beam curable resin is used as the coating material, the surface layer is formed when the substrate portion is made of a foam in which void cells are dispersed. The surface layer can be smoothly formed without burying the void cells exposed on the surface of the substrate portion with the surface layer, while the coating material coated with is instantly cured by electron beam curing or ultraviolet curing. Even when the coating is made of a non-foamed material without cells, it is possible to prevent the coating from flowing after coating and to prevent the coating thickness from changing by instantly curing the coating.

  According to the invention of <3>, at least one of the spray gun for spraying the paint and the base part in the state where the base part is rotated around the shaft part is relatively displaced in the base part length direction with respect to the other. Since the coating material is sprayed, the peripheral surface of the base portion can be continuously formed in a spiral shape along the length direction of the conductive roller, and the coating material can be consumed wastefully. In addition, a coating film having a smooth and uniform thickness can be formed.

  According to the invention <4>, one or both of the tank heating device and the pipeline heating device are provided, and at least one of the gas stored in the gas reservoir and the gas passing through the gas supply pipe is raised. Since the gas heating device for heating is provided, the temperature of the paint can be increased efficiently.

  According to the invention <5>, since the paint return pipe for returning the paint supplied from the paint tank via the paint supply pipe to the paint tank by bypassing the spray gun is provided, the paint is not used. However, the temperature of the paint in the paint tank and the paint supply piping path can be raised, and the paint can be in a good atomized state immediately after the start of spraying.

  According to the invention of <6>, the shaft portion is pivotally supported at both ends in the length direction, the base portion disposed around the shaft portion, and the surface layer covering the base portion. Since it is formed by the above-described method, as described above, the drying process is simplified to realize cost reduction and space saving, and at the same time, the film thickness change in the drying process is prevented and uniformity is achieved. For example, when the conductive roller is a developing roller or a charging roller, a uniform developing performance or charging performance is carried on the conductive roller, and the image forming apparatus It can contribute to high image quality.

  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, chlorotrifluoroethylene-vinyl ether copolymer, tetrafluoroethylene-vinylidene fluoride copolymer, chlorotrifluoroethylene- And vinyl ester copolymers, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymers, etc. Dispersion type water-based fluororesin is preferably used dispersed in, more preferably dispersion type water-based fluorine resin dispersed with fine particles of polytetrafluoroethylene in water 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, other resins mixed with the fluororesin include polyvinyl acetal resin, urethane resin, polyester resin, acrylic resin, nylon resin, epoxy resin, vinylidene chloride copolymer, acrylic-urethane copolymer, and the like. The surface layer 4 can be formed by mixing one or more of these with the fluororesin. 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.

  In the surface layer 4, when it is desired to ensure the smoothness, a water-based resin is preferably used. The water-based resin may be any type such as a water-soluble type, an emulsion type, and a suspension type as long as the solvent is water, but in particular, an acrylic hot water-soluble resin having active hydrogen such as a carboxyl group, a hydroxyl group, and an amino group. Is preferred. Acrylic resin has a much lower dielectric constant than urethane and nylon, which have been generally used as charging roller resins, and has a smaller electrostatic capacity. The electric attractive force / repulsive force is reduced, and the charging noise can be reduced.

  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. Examples thereof include compounds having two or more compounds, for example, polyol compounds, polyisocyanate compounds, polyaldehyde compounds, polyamine compounds, polyepoxy compounds and the like. 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.

  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. Furthermore, when a paint made of these resins is used, the surface layer can be instantly solidified by irradiating it with ultraviolet rays or electron beams after completion of the coating, and left in the same posture under fluidized conditions. In contrast to this, the change in the thickness of the surface layer can be suppressed.

  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 for 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 FIG. FIG. 2A is a plan view showing a coating apparatus for forming a surface layer 4 by spraying paint, and FIG. 2B is a cross section showing a cross section corresponding to the arrow bb in FIG. The coating apparatus 10 includes a roller rotation driving unit 24 that rotates the conductive roller 1 pivotally supported by support members 23 at both ends in the length direction, and a spray gun 11 that sprays the conductive roller 1 with paint. The gun traverse device 20 that displaces the spray gun 11 in the length direction of the conductive roller 1 in synchronization with the rotation of the conductive roller 1 and the paint supply device 30 that supplies the paint to the spray gun 11 are driven to rotate the roller. The means 24 can be constituted by, for example, a servo motor with a speed reducer, and the gun traversing device 20 includes a mounting block 15 for attaching the spray gun 11 and a block 15 as shown in FIG. A servo motor 14 with reduction gear to traverse through the screw 12, can be configured by comprising a linear guide 13 for guiding the straight running of the block 15. In the figure, reference numeral 25 denotes a common base for commonly supporting the roller rotation driving means 24, the support member 23, and the gun traversing device 20, and 26 is not applied by separating the coating space from other parts. It is a painting booth to prevent the paint from spreading.

  The conductive roller 1 is configured to be detachable with respect to one support member 23 by means (not shown), and the conductive roller 1 on which the surface layer 4 is formed is taken out from the support member 23. The conductive roller 1 on which the surface layer 4 is not formed can be mounted on the support member 23.

  FIG. 3 is a piping system diagram showing a configuration example of the paint supply device 30. The paint supply device 30 is a paint tank 31 that contains paint, and a paint pump that sucks paint from the paint tank 31 and pumps it to the spray gun 11. 32 and a paint supply pipe 34 for guiding the paint from the paint tank 31 to the spray gun 11, a gas reservoir 46 for storing a compressed gas for atomizing the paint in the spray gun 11, and spraying the gas reservoir 46 from the gas reservoir 46. A gas supply pipe 42 for supplying the gun 11 is provided.

  In addition, as an example of the gas for atomization, it is preferable to use air and nitrogen gas, and these can supply a gas cylinder or a compressor as a gas source, and when using a gas cylinder as a gas source, this A gas cylinder can be used as the gas reservoir 46.

  A paint pressure adjusting valve 45 for adjusting the pressure of the paint is provided in the middle of the paint supply pipe 34, and an air pressure adjusting valve 43 for adjusting the pressure of the atomizing compressed gas is provided in the middle of the gas supply pipe 42. For example, the spray conditions can be changed manually or automatically according to the type of the conductive roller 1.

  The present invention is characterized in that both the paint and the atomized compressed gas are heated in order to raise the temperature of the paint before spraying to lower the viscosity. In addition to a tank heating device 33 that raises the paint in 31 to a predetermined temperature and then maintains the temperature, and a pipe heating device 36 that heats the paint passing through the paint supply pipe 34 to a predetermined temperature, Even when the paint is not sprayed from the spray gun 11, a paint return pipe 35 for circulating the paint is provided so that the paint does not stagnate and cool down in the paint supply pipe 34, and is further stored in the gas reservoir 46. At least one of a reservoir gas heating device 47 for raising the temperature of the gas and a supply pipe gas heating device 49 for raising the temperature of the gas passing through the gas supply pipe 42 is provided.

  Further, a flow path switching valve 41 is provided for the circulation of the paint, and when spraying paint from the spray gun 11 onto the conductive roller base 3, the outlet to the spray gun 11 side is opened and when spraying is not performed. The paint return pipe 35 is configured to open the outlet and circulate the paint. Furthermore, preferably, the paint tank 31 is provided with a stirrer 43 for making the temperature of the paint more uniform.

  Since the spray gun 11 sprays the paint while being displaced, the paint supply pipe 34 and the paint return pipe 35 are connected to the spray gun 11 through flexible hoses 37a and 37b.

  Here, the tank heating device 33 can be constituted by, for example, a temperature control jacket that is attached so as to go around the inside or the outside of the tank body, and this temperature control jacket is formed by passing steam or hot water inside. Alternatively, this can be used as the heat source by using an electric heater. Further, the pipe heating device 36 can also be constituted by a similar temperature control jacket surrounding the outside of the paint supply pipe 34 in the radial direction. Further, it is preferable that the paint supply pipe 34 and the paint return pipe 3 are kept in a wide range as much as possible in order to further stabilize the paint temperature and save energy.

  Further, the reservoir gas heating device 47 and the supply pipe gas heating device 49 can be constituted by, for example, an electric heater provided in the gas reservoir 46 and the gas supply pipe 42. A temperature sensor (not shown) is disposed in the gas supply pipe 42 immediately before the spray gun 11, and the electric heater is turned on or off depending on the temperature detected by the gas temperature sensor, or the current flowing through the electric heater is changed. Can be performed.

  The temperature of the paint immediately before atomization when the temperature is raised using such a heating device is preferably 30 to 100 ° C, more preferably 40 to 70 ° C. 30 ° C is the minimum temperature necessary to keep the viscosity of the paint low, and if it exceeds 100 ° C, if it exceeds this temperature, the paint components will evaporate or gel and stable coating Because it becomes difficult.

  Further, the temperature of the gas immediately before atomization for making the temperature of the paint immediately before atomization within the above range is preferably 50 to 150 ° C.

  In the above example, both the tank heating device 33 and the pipe heating device 36 are provided. However, only one of them may be used depending on the type of paint and the coating conditions. Further, in order to improve the coating efficiency, the coating material is sprayed by an electrostatic coating method in which a high voltage is applied between the peripheral surface of the base portion 4 of the conductive roller 1 and the spray gun 11 to assist the electrostatic force. You can also

  Here, it is preferable that the paint pressure immediately before atomization is 100 to 1000 kPa, and the pressure of the atomizing compressed gas is 50 to 1000 kPa, whereby a good atomization state can be obtained.

  In order to form the surface layer 4 by coating the base portion 3 of the conductive roller 1 using the coating apparatus 10 configured as described above, after the base portion 2 is mounted on the support member 23, the roller is driven to rotate. While the motor constituting the means 24 is driven to rotate the base 3 in the direction of arrow A, the servo motor 14 with a speed reducer is driven to synchronize the spray gun 11 in the direction of arrow B with the rotation of the base 3. At this time, while the base portion 3 rotates once, the spray gun 11 is moved by a pitch shorter than the width of the base portion 3 and narrower than the spread width of the paint. The surface layer 4 can be formed of a spirally extending coating film as shown in FIG. 2A from one end of the portion 3 toward the other end.

  Thereafter, the conductive roller 1 having the surface layer 4 formed in this manner is taken out of the support member 23, and the surface layer 4 is cured in a drying process (not shown) or using an ultraviolet curing device or an electron beam curing device. The manufacture of the conductive roller 1 is completed.

  The coating apparatus 10 was used to change the type of paint and the temperature condition of the paint at the time of spraying. The experiment was carried out to form the surface layer 4 by spraying the paint under the respective conditions. The surface roughness and thickness of the coating film were measured. The results are summarized in Table 1. For paint A and paint B in Table 1, these formulations are shown in Table 2. These coating materials are all ultraviolet curable coating materials. The amount of solvent (*) in Table 2 represents the mass ratio of the solvent to the total amount of the paint in%, and the paint temperature at the time of spraying is the paint temperature in the tank and the atomized air. It was changed by changing the temperature.

  In addition, for the paint used in the above experiment, the viscosity when the temperature is changed is measured, the temperature dependence curve of the paint viscosity is obtained, the measured paint temperature during spraying, and the temperature dependence curve of the paint viscosity From this, the viscosity of the paint at the time of spraying was estimated, and this is also shown in Table 1 as “viscosity”.

  In Table 1, “Applicability” means “○” when the paint can be sprayed stably, “△” when the paint can be sprayed but unstable, and no atomization of the paint. The possible items are indicated by “x”, and “Pass / Fail Judgment” is “Pass” when the applicability is “O” and the surface roughness Ra of the coating film is 2.0 μm or less. The thing was expressed as "fail".

  “Paint temperature” in Table 1 represents the temperature at the time of spraying at the point detected by the thermocouple by disposing a thermocouple contact in the paint path of the spray gun.

  The measuring instrument for determining the temperature dependence curve was a rheometer manufactured by ThermoHaake (model: ReoStress300 + TC81). In this measurement, the measurement liquid is sandwiched between the cone and the plate, and the viscosity is obtained from the torque acting on the cone when the cone is rotated and reciprocated at a constant frequency. The model number was c20 / 1 (manufactured by the same company, diameter 20 mm, cone cone tilt angle 1 degree with respect to the plate), and the frequency of rotational reciprocation of the cone was 1 Hz.

  The prototype conductive roller was a developing roller, and its size was 18 mm in outer diameter, 8 mm in diameter of the shaft portion, and 250 mm in length of the base portion.

  As can be seen from Table 1, the conductive rollers of the examples have good atomization state, excellent surface properties of the coating film, and more uniform film thickness than those of the comparative examples. It can be seen that

  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 the top view and sectional drawing which show the coating device which forms the surface layer of an electroconductive roller. It is a piping system diagram which shows the coating material supply apparatus of a coating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A Conductive roller 2, 2A Shaft part 3, 3A Base part 4, 4A Surface layer 10 Coating device 11, 11A Spray gun 12 Ball screw 13 Linear guide 14 Servo motor with reduction gear 15 Mounting block 20 Gun traverse device 23 Support Member 24 Roller rotation driving means 25 Common base 26 Paint booth 30 Paint supply device 31 Paint tank 32 Paint pump 33 Tank heating device 34 Paint supply piping 35 Paint return piping 36 Pipe heating device 37a, 36b Flexible hose 41 Flow path switching valve 42 Gas supply piping 43 Air pressure adjustment valve 45 Paint pressure adjustment valve 46 Gas reservoir 47 Reservoir gas heating device 48 Stirrer 49 Supply piping gas heating device

Claims (6)

Manufacture of a conductive roller that forms a surface layer by spraying paint atomized by compressed gas on the peripheral surface of a cylindrical base provided on the outside of a shaft supported at both ends in the lengthwise direction In the method
A method for producing a conductive roller, wherein both the paint and the compressed gas are heated so that the viscosity of the paint is 1 to 1000 mPa · s.   The method for producing a conductive roller according to claim 1, wherein a paint containing an ultraviolet curable resin or an electron beam curable resin is used.   A spray gun that sprays paint while relatively displace- ing at least one of the spray gun for spraying paint and the base portion relative to the other in the length direction of the base portion while the base portion is rotated around a shaft portion. 3. A method for producing a conductive roller according to 1 or 2. Manufacture of a conductive roller that forms a surface layer by spraying paint atomized by compressed gas on the peripheral surface of a cylindrical base provided on the outside of a shaft supported at both ends in the lengthwise direction A conductive roller coating apparatus used in the method,
Spray gun for spraying paint, paint tank for containing paint, paint supply pipe for transporting paint from paint tank to spray gun, gas reservoir for storing compressed gas, and gas for supplying compressed gas from gas reservoir to spray gun The gas stored in the gas reservoir is provided with at least one of a tank heating device that includes a supply pipe and raises the temperature of the paint contained in the paint tank and a pipe heating device that raises the temperature of the paint passing through the paint supply pipe. And a conductive roller coating device in which a gas heating device is provided to raise the temperature of at least one of the gas passing through the gas supply pipe.   The conductive roller coating apparatus according to claim 4, further comprising a paint return pipe that bypasses the spray gun and returns the paint supplied from the paint tank via the paint supply pipe to the paint tank.   The shaft portion is pivotally supported at both ends in the length direction, the base portion is disposed around the shaft portion, and the surface layer covers the peripheral surface of the base portion. A conductive roller formed by the method for manufacturing a conductive roller according to claim 3.

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