JP2006088016A - Method for manufacturing conductive roller and conductive roller manufactured by this method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a conductive roller capable of performing coating without burying a void cell of a foamed body when a base part comprising the foamed body is coated with coating to form a surface layer, having no specific and ununiform part such as a removal line on the surface layer and capable of further forming the surface layer with a uniform thickness even in a roller body and in the roller relative to each other, and a conductive roller formed by this method. <P>SOLUTION: At an attitude that a photogravure roll 11 and a base part of the conductive roller 1 are crossed at a predetermined angle including 90° and their peripheral surfaces are brought into contact with and approach to each other while feeding the coating having a viscosity of 200-100,000 mPa×S at 25°C to the peripheral surface of the photogravure roll 11, at least one of the photogravure roll 11 and the base part of the conductive roller 1 is relatively displaced relative to the other in a base part length direction while rotating both of the photogravure roll 11 and the base part of the conductive roller 1. The periphery of the base part of the conductive roller 1 is coated with the coating to form the surface layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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. It is related with what can apply | coat and can form a surface layer in high quality.

  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.

  As the columnar base portion, one obtained by adding a conductive agent to a single elastomer or a foam obtained by foaming it is used. Here, the foam includes not only those foamed chemically using a foaming agent but also those in which air is mechanically entrained in an elastomer, resulting in dispersion of void cells. When softness is required for the conductive roll, a base is preferably made of a foam.

  However, when an attempt is made to form a surface layer by applying a coating to a base portion made of such a foam, if the viscosity of the coating is low, the coating will flow and the coating will pass through the void cells exposed on the surface. There is a possibility that not only the elastic characteristics of the base portion and the electrical characteristics due to the surface layer will not be obtained, but also these characteristics may change from place to place. As a countermeasure, a method of forming a surface layer by using a highly viscous paint, reducing fluidity, and not filling void cells exposed on the surface can be considered.

  On the other hand, as a conventional method of forming a surface layer by applying a paint, 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 by dipping coating or spray coating ( For example, see 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 body is coated in a spiral shape, no separation line appears and the uniformity is improved in that respect, but a roll with a flat surface is used as the application roll. Therefore, the film thickness of the paint on the application roll changes due to changes in properties such as the viscosity of the paint and slight changes in application conditions. As a result, the film thickness of the surface layer of the conductive roller When this method is used for a conductive roller that requires a high degree of uniformity, it has been difficult to ensure the required surface layer film quality.

  If you increase the film thickness to be applied at one time in order to suppress this variation in film thickness, when using a highly viscous paint, there will be a step that appears at the boundary of the spiral when applied in a spiral pattern. There was a problem.

  The present invention has been made in view of such problems, and when a surface layer is formed by applying a paint to a base portion made of a foam, it may be applied without filling the void cells of the foam. In addition, the surface layer does not have a peculiar non-uniform portion such as a separation line, and the thickness of the surface layer can be made uniform even within one roller or between rollers. And it aims at providing the conductive roller formed by this method.

<1> is a method for producing a conductive roller having a surface layer on the outer side of a cylindrical base portion made of a foam that is pivotally supported at both ends in the length direction and exposes some void cells on the peripheral surface. In
While supplying paint with a viscosity of 200 to 100,000 mPa · S at 25 ° C 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 these peripheral surfaces contact each other Alternatively, while rotating both the gravure roll and the conductive roller base in a close attitude, at least one of the gravure roll and the conductive roller base is relatively displaced with respect to the other in the length direction of the base to conduct electricity. A method for producing a conductive roller in which a surface layer is formed by applying the coating material on the periphery of a conductive roller base portion.

  <2> is a method for producing a conductive roller according to <1>, wherein a gap of less than 100 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 is an electron beam effect resin or an ultraviolet curable resin containing an ultraviolet polymerization initiator. is there.

  <4> 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 <3>.

  <5> consists of a shaft portion pivotally supported at both ends in the length direction, a base portion disposed around the shaft portion, and a surface layer covering the peripheral surface of the base portion. <1>-<4> It is a conductive roller formed by the manufacturing method of the conductive roller in any one of.

  According to the invention of <1>, since the paint having a viscosity of 200 to 100,000 mPa · S at 25 ° C. is applied, the surface layer can be formed without filling the void cells on the surface of the base body made of a foam due to its poor fluidity. As a result, the elastic performance of the base portion and the electrical performance of the surface layer can be made desired and uniform. If the viscosity of the paint at 25 ° C exceeds 100,000 mPa · S, a spiral coating film step remains, and if this viscosity is less than 200 mPa · S, the voids exposed on the surface of the substrate part The paint flows into the cell, and the desired roller characteristics cannot be carried.

Further, during application, while supplying 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 the peripheral surfaces are in contact with or close to each other. By rotating both the roll and the conductive roller base part, the surface layer is formed by applying at least one of the gravure roll and the conductive roller base part relative to the other to form a surface layer. , Can form a surface layer without leaving line,
In addition, as the application roll, a gravure roll whose peripheral surface is made of a gravure is used, the amount of the paint retained on the peripheral surface can be made constant even if the viscosity of the paint slightly changes. As a result, the surface layer Can be formed uniformly.

  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. Since the gap is less than 100 μm, the paint can be transferred from the gravure roll to the base without forming an unnecessary film thickness on the peripheral surface of the gravure roll. As a result, the film thickness can be controlled with high accuracy.

  According to the invention <3>, since an electron beam curable resin or an ultraviolet curable resin containing an ultraviolet polymerization initiator is used, the coating applied with the surface layer is made by electron beam curing or ultraviolet curing. By instantaneously curing, it is possible to more reliably prevent the coating material from flowing into the void cells exposed on the surface of the substrate.

  According to the invention of <4>, since the coating material 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 obtained by controlling the particle size distribution of the particles in the paint. The degree can be applied to the conductive roller.

  According to the invention of <5>, 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 the surface layer is formed by the above-described method, for example, when the conductive roller is a developing roller or a charging roller, uniform developing performance or charging performance is obtained. Can be carried and can be used for a high-quality image forming apparatus.

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, an elastomer is foamed using a foaming agent, or a foamed material that is foamed by mechanically entraining air is used to impart conductivity by adding a conductive agent. 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.

  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 or nylon, which has been generally used as a charging roller resin, 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. 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.

  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 11 a that draws up the paint from the tank 12 and transports it is formed with a concave portion 11 c that becomes a gravure plate, and the paint drawn up by the peripheral surface 11 a is scraped off by the doctor blade 16. Thus, the dominant factors that determine the transport amount of the paint on the gravure roll 11 are the number of rotations and the total volume of the recess 11c, as compared to the case of coating with a flat roll without the recess 11c. It can be made highly accurate.

  In addition, since the transfer rate when the paint held in the recess 11c is transferred to the peripheral surface of the base portion 3 is influenced by the viscosity of the paint, it is determined mainly by the shape of the recess 11c. However, the surface layer 4 having a more accurate film thickness can be formed on the base portion 3 as compared with a flat roll.

FIG. 5 is a schematic diagram showing an example of a gravure pattern. In addition to the lattice type, pyramid type, oblique line type, turtle shell type, TF type and round mesh type patterns shown in this order in FIGS. For example, when a grid-type gravure plate is used, the density of the grid is 10 to 300 lines / inch, the depth is 20 to 650 μm, and the volume of the recess is 5 to 400 cm ³ / m ^2. It is preferable to secure a highly accurate film thickness.

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. 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.

  Further, it is preferable that the direction of relative rotation between the base 3 of the conductive roller 1 and the gravure roll 11 is a direction in which a shearing force is applied to the coating because the smoothness of the coating surface can be improved. As exemplified in the above, it is preferable that the conductive roller tangential direction components of the peripheral surface speed in the portion where the base portion 3 and the gravure roll 11 are in contact or close to each other 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.

  In the present invention, a paint having a viscosity at 25 ° C. of 200 to 100,000 mPa · S is used. It is difficult to form such a high-viscosity paint using a coating method other than the roll coater type. For example, the method of forming the surface layer 4 by spraying uses such a high-viscosity paint. This is because it is difficult to atomize, and on the other hand, when the coating contained in the dip tank is immersed, the viscosity is too high and the film thickness becomes extremely thick, which is difficult to realize.

  The advantage of using such a high-viscosity paint is that the paint is difficult to flow, so that the void cell 34 s exposed on the surface of the base portion 33 is surfaced as shown in FIG. The surface layer 36A having a uniform thickness can be formed without being filled with the layer 37 to smoothly cover the base portion 33. If the viscosity of the paint is low, it corresponds to FIG. 7 (a). As shown in FIG. 7 (b), the paint flows into the void cells 34s exposed on the surface and fills the cells 34s, and the base layer 33 is provided with the elastic characteristics and the surface layer 36. The conductive characteristics to be achieved cannot be made desirable, and these characteristics become non-uniform.

  Further, when the surface layer 4 is formed using a paint containing an ultraviolet curable resin or an electron beam curable resin, the viscosity condition satisfies 200 to 100,000 mPa · S, and this is instantly cured immediately after coating. As a result, it is possible to suppress the flow and bring about the same effect as the high viscosity. 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 hold and transport the surface layer 4, the surface layer 4 having a uniform surface roughness can be formed.

For example, when the conductive roller is a developing roller, the particles contribute to enhancing the performance of charging the toner, and a preferable surface roughness Ra is 0.5 to 1.5 μm. In this case, as the particles for supporting the surface roughness, inorganic fine particles such as rubber or synthetic resin fine particles, carbon fine particles and silica-based fine particles are preferable. Silicone rubber, silicone resin, fluororesin, urethane Elastomers, polyolefin resins, epoxy resins, polystyrene resins, urethane acrylates, melamine resins, phenol resins, (meth) acrylic resins, glassy carbon particles and silica particles are particularly preferable. These fine particles may be used alone or in combination of two or more.

  When the coating apparatus 1 is used, the structure shown in FIG. 1A is formed by forming the surface layer 4 by changing the viscosity of the coating for application rolls having various patterns of peripheral surfaces. The developing roller was made as a prototype, and the thickness of the formed surface layer 4 was examined. Variations in film thickness were also recorded for these samples, which were applied with a paint having a very low viscosity and deviated from the requirements of the present invention. The application roll having a smooth surface had a surface roughness Ra of 1 μm or less.

  In addition, after completion of the conductive roller, it was cut to investigate whether or not the paint was flowing into the void cell exposed on the surface.

  The coating conditions and evaluation results are shown in Table 1. Table 2 shows detailed blending amounts and viscosities for each of the paint types P1 to P6 in Table 1. “Surface roughness (mm): Ra” in Table 1 is a result of measurement using Surfcom 590A (manufactured by Tokyo Seimitsu).

  The conductive roller used in the trial production was a developing roller, and the size was 18 mm in outer diameter, 8 mm in diameter of the shaft portion, 250 mm in length of the base portion, and 0.005 to 0.05 mm in thickness of the surface layer.

  As is clear from Table 1, the conductive rollers of the examples all have a much smaller variation rate of the film thickness than that of the comparative example, and the inflow of the paint into the surface gap cell of the paint is completely completed. As a result, it can be seen that the surface smoothness is also excellent.

  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 31 Spiral coating 32 Spiral coating edge 33 Base portion 34 Void cell 34s Void cell 36, 36A exposed on the surface

Claims (5)

In a method of manufacturing a conductive roller having a surface layer on the outer side of a cylindrical base portion made of a foam that is pivotally supported at both ends in the lengthwise direction and exposes some void cells on the peripheral surface,
While supplying paint with a viscosity of 200 to 100,000 mPa · S at 25 ° C to the peripheral surface of the gravure roll, the gravure roll and the conductive roller base part intersect at a predetermined angle including 90 degrees, and these peripheral surfaces contact each other Alternatively, while rotating both the gravure roll and the conductive roller base in a close attitude, at least one of the gravure roll and the conductive roller base is relatively displaced with respect to the other in the length direction of the base to conduct electricity. A method for producing a conductive roller in which a surface layer is formed by applying the coating material on the periphery of a conductive roller base portion.   The method for producing a conductive roller according to claim 1, wherein a gap of less than 100 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 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 1-3 which supplies the coating material containing a particle | grain with an average particle diameter of 1-30 micrometers to the surrounding surface of a gravure roll.   The shaft portion is 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 any one of the above.

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