JP2005121881A - Manufacture of conductive roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating method capable of efficiently and uniformly forming a thick conductive layer, instead of a conventional dip-coating method, in the case of manufacturing a conductive roller. <P>SOLUTION: Coating material is applied on a base substance by making the base substance pass through the bottom part of a coating material storage container which is arranged outside the base substance in a radial direction in contact with the whole periphery of the base substance, and relatively displacing the base substance in an axial direction, then, a conductive layer is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a conductive roller in which a conductive layer constituting a conductive roller is formed by applying a coating material, and more particularly to a method for forming a thick conductive layer.

  2. Description of the Related Art Conventionally, a dip coating method has been widely used as a method for forming a conductive layer of a conductive roller used in an electrophotographic apparatus such as a copying machine or a printer by applying a coating material. For example, a charging roller that directly contacts the photoreceptor and injects a charge into the photoreceptor is formed by forming a base layer around the shaft using a mold, and then immersing a large number of charging rollers together in a dip solution. A method of forming a skin layer by applying a dip solution on the outside of the base layer is widely employed (see, for example, Patent Document 1).

  On the other hand, this charging roller has been developed to reduce the overall diameter including the base layer in order to reduce the cost. However, in order to further reduce the cost, the base layer does not require investment in the mold, and is a coating method. It is being considered to form with.

However, in order to efficiently dip the thick layer exemplified in such a base layer, it is necessary to use a high-viscosity dip solution. In this case, a high-viscosity dip solution stored in the dip tank Is likely to cause a large viscosity difference between the top and bottom due to solvent volatilization, sedimentation of the filler, etc., and when the dip coating with a dip liquid having a viscosity difference is performed, the resulting conductive layer will have different characteristics in the axial direction. In order to solve this problem, there was a problem that even when trying to stir the dip solution, it was difficult to stir because a large amount of high-viscosity dip solution was stored in the dip tank, and bubbles were generated. .
JP 2003-131474 A

  The present invention has been made in view of such problems, and an object of the present invention is to provide a coating method capable of efficiently and uniformly forming a thick conductive layer in place of conventional dip coating. And

(1) In the present invention, when the conductive layer constituting the conductive roller is formed by applying a coating material on the outer peripheral surface of the substrate,
Conductive coating is performed by applying a coating material to a coating material container disposed outside the substrate in the radial direction and provided in contact with the entire circumference of the substrate by axially displacing the substrate through the bottom of the container. It is a manufacturing method of a property roller.

  (2) The present invention is the method for producing a conductive roller according to (1), wherein the viscosity of the coating material immediately before application is 10,000 mPa · s or more.

  (3) The present invention is the method for producing a conductive roller according to (1) or (2), wherein the conductive layer is formed by applying a solventless coating material.

  (4) The present invention is the method for producing a conductive roller according to any one of (1) to (3), wherein the conductive layer is formed by applying a two-component curable coating material.

  (5) In the present invention, in any one of (1) to (4), the conductivity of changing the axial relative displacement speed in the middle of displacement so that the central portion in the axial direction of the conductive roller is thicker than both ends. It is a manufacturing method of a property roller.

  (6) According to the present invention, in any one of (1) to (5), the conductive roller that sequentially cures the applied portion of the conductive layer in the axial direction by a heater disposed coaxially with the coating material container. It is a manufacturing method.

  (7) The present invention is the method for producing a conductive roller according to any one of (1) to (6), wherein the conductive layer is a base layer adjacent to the outside in the radial direction of the shaft.

  According to the invention of (1), since the base is passed through the bottom of the coating material container and is relatively displaced in the axial direction, the liquid level of the container does not need to be greater than the axial length of the conductive layer. Therefore, the liquid surface height can be set low to eliminate the difference in the upper and lower concentrations of the coating material in the container. In addition, the capacity of the coating material container is naturally small, and even if it is necessary to stir the paint, it can be easily stirred. Can be formed.

  According to the invention of (2), since the viscosity of the coating material is as high as 10,000 mPa · s or more, as described above, it is extremely practical in that it is difficult to use a high-viscosity material with other coating methods. Can provide a high method.

  According to the invention of (3), since the coating is performed using a solvent-free coating material, that is, a coating material having a resin solid content of 100%, the resin content and the solvent are separated vertically in the container, The difference is not different, and this allows a thick film to be formed more uniformly.

  According to the invention of (4), since the coating material is a two-component curable material, even if the pot life is short and cannot be stored for a long time in the dip tank, The conductive layer can be formed efficiently and uniformly.

  According to the invention of (5), the speed of the relative displacement in the axial direction is changed in the middle of the displacement so that the central portion in the axial direction is thicker than both ends. Can be formed. It should be noted that the crown-shaped roller can form a contact surface with the photosensitive drum that is uniform in the axial direction when the both ends are held and pressed against the photosensitive drum, and is advantageous for obtaining a uniform image in the axial direction. It is a thing.

  According to the invention of (6), since the coating completion portion is sequentially cured by the heater arranged coaxially with the coating material container, the coating thickness after coating is prevented and the film thickness is made more uniform. The process of painting and curing can be carried out efficiently with a predetermined tact one by one.

  According to the invention of (7), since this coating method is applied to the thick base layer, the base layer can be uniformly formed at low cost, and as a result, all the conductive layers of the conductive roller are the same. It can be formed by the method, and the cost can be further reduced.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a structure of a charging roller as an example of a conductive roller formed by the manufacturing method of the present embodiment. The charging roller 10 includes a shaft 1 and a base layer disposed around the shaft 1. The elastic layer 2, the skin layer 4 forming the roller peripheral surface, and the resistance adjusting layer 3 provided between the elastic layer 2 and the skin layer 4. Here, the shaft 1 is a portion that is pivotally supported by an electrophotographic apparatus such as a printer, and is made of metal or plastic.

The elastic body constituting the elastic layer 2 may be an elastic body capable of obtaining a good contact state with a charged body such as a photoreceptor, and may be a known rubber or resin, or a foam thereof (hereinafter referred to as “ Form)). Specifically, silicone rubber, butadiene rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber, natural rubber, etc. are used as the base rubber. A rubber composition or polyurethane is exemplified. In the case of foam, the expansion ratio of rubber or polyurethane foam is not particularly limited, but is preferably 1.2 to 50 times, particularly preferably about 1.5 to 10 times, and the foam density is 0.1 to 0.00. A value of about 8 g / cm ³ is appropriate. When the foam density is smaller than 0.1 g / cm ³ , the compression set becomes large, and when it is larger than 0.8 g / cm ³ , the shape hardly changes even with the same external force. The foam density is more preferably 0.4 to 0.6 g / cm ³ .

By adding a conductive agent to the elastic layer 2, conductivity can be imparted or adjusted to a predetermined resistance value. The conductive agent is not particularly limited. Lauryltrimethylammonium, stearylmethylammonium, octadodecyltrimethylammonium, hexadecyltrimethylammonium, modified fatty acid / dimethylethylammonium perchlorate, chlorate, borofluoride , Cationic surfactants such as quaternary ammonium salts such as halogenated benzyl salts such as sulfates, etosulphate salts, benzyl bromide salts, benzyl chloride salts, aliphatic sulfonates, higher alcohol sulfates, Anionic surfactants such as higher alcohol ethylene oxide addition sulfate, higher alcohol phosphate, higher alcohol ethylene oxide addition phosphate, higher alcohol ethylene oxide, polyethylene glycol fatty acid ester Antistatic agents such as polyhydric nonionic antistatic agents such as alcohol fatty acid _{ester, NaClO 4, LiAsF 6, LiBF} 4, NaSCN, KSCN, such as NaCl Li ^+, Na ^+, periodic table first K ^+, etc. Electrolytes such as group metal salts or NH ₄ ⁺ salts, conductive carbons such as ketjen black and acetylene black, rubber carbons such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, Oxidized carbon for color (ink), pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium and other metals and metal oxides, polyaniline , Conductive polymers such as polypyrrole and polyacetylene. In this case, the blending amount of these conductive agents is appropriately selected according to the type of the composition, and the volume resistivity of the elastic layer is usually 10 ⁰ to 10 ⁸ Ω · cm, preferably 10 ² to 10 ⁶ Ω · cm. It is adjusted to become.

  In addition to the conductive agent, a thickener is added to the elastic layer 2 in order to thicken the coating film formed by a single coating operation. Further, if necessary, an appropriate amount of known additives such as an antifoaming agent, a leveling agent, a dispersant, a thixotropy imparting agent, a wetting agent, an antiblocking agent, a crosslinking agent, and a film forming aid can be blended.

  The thickness of the elastic layer 2 is appropriately set according to the form and size of the roller, the layer configuration, and the like, and is not particularly limited, but is usually 0.2 to 5.0 mm, particularly 0. It is preferable to be about 5 to 2.0 mm.

The resistance adjusting layer 3 disposed on the outer side in the radial direction of the elastic layer 2 is a resin composition obtained by adding a conductive agent to a low resistance resin base material having a volume resistivity of 1 × 10 ⁴ to 1 × 10 ¹⁰ Ω · cm. It is formed by. The low-resistance resin base material constituting this resin composition may be any material as long as it has the above-mentioned volume resistivity, and is not particularly limited. Specifically, rubber, urethane resin, acrylic resin Urethane resin, acrylic resin, ester resin, nylon resin, phenol resin, epoxy resin, fluororesin, silicone resin and the like can be mentioned, and one or more of these can be mixed and used, especially urethane resin, acrylic resin Water-based resins such as urethane resins and acrylic resins are preferably used. In addition, the more preferable resistance value of this low resistance resin base material is 1 × 10 ⁵ to 1 × 10 ⁸ Ω · cm.

  As a conductive agent added to the low-resistance resin base material, an ion conductive material having a molecular weight of 30 to 800, preferably a molecular weight of 100 to 500 is used. Examples of the ion conductive material include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium such as lauryltrimethylammonium, octadecyltrimethylammonium such as hexadecyltrimethylammonium and stearyltrimethylammonium, benzyltrimethylammonium, benzyltriethylammonium, benzyltributylammonium, modified Ammonium perchlorate such as aliphatic dimethylethylammonium, chlorate, hydrochloride, bromate, iodide, borofluoride, sulfate, alkyl sulfate, carboxylate, sulfonate, etc. Organic ionic conductive materials: lithium, sodium, calcium, magnesium and other alkali metal or alkaline earth metal perchlorates, chlorates, hydrochlorides, odors Salt, iodine salt, fluoroboric acid salts, trifluoromethyl sulfate, and inorganic ion-conductive material such as a sulfonic acid salt can be exemplified, can be used alone or in combination of two or more thereof. Among these, although not particularly limited, one or more quaternary ammonium perchlorates are particularly preferably used.

The resistance adjustment layer 3 is for adjusting the electrical resistance value of the charging roller 10, and the resistance value of the resistance adjustment layer 3 is appropriately set according to the resistance value of the elastic layer 2 and the resistance value required for the roller. However, it is usually set to 1 × 10 ³ to 1 × 10 ⁸ Ω · cm, particularly 1 × 10 ⁵ to 1 × 10 ⁷ Ω · cm. In this case, the amount of the ion conductive substance as the conductive agent is set to an appropriate amount to achieve this resistance value, but is usually 0.1 to 20 with respect to 100 parts by weight of the low resistance resin substrate. In the present invention, since the low resistance resin base material is used as the base resin of the resistance adjusting layer 3, the above-mentioned appropriate amount can be obtained with such a relatively small amount. The resistance adjustment layer 3 having a resistance value can be easily obtained.

  In addition to the ionic conductive material, an appropriate additive can be blended in the resistance adjusting layer 3. An appropriate amount can be blended depending on the low-resistance resin substrate to be used, and the film-forming aid, dispersant, thickener, leveling agent, thixotropy-imparting agent, structure can be used without departing from the purpose of the resistance adjusting layer 3. An appropriate amount of a known additive such as a viscosity-imparting agent can be blended.

  The thickness of the resistance adjusting layer 3 is appropriately selected according to the thickness of the elastic layer 2 and the form of the charging roller 10 and is not particularly limited, but is usually 10 to 500 μm, particularly 50 to 300 μm. If the thickness is less than 50 μm, it may be difficult to adjust the resistance sufficiently. On the other hand, if the thickness exceeds 300 μm, the elastic layer becomes relatively thin and the roller hardness increases. Or cost may be higher than necessary.

  Next, as a material for forming the skin layer 4, a known rubber or resin can be used, and is not particularly limited, but is a urethane-modified acrylic resin, polyurethane resin, acrylic resin, polyamide resin, and fluorine resin. Etc., and one or more of these may be used in combination. Among these, a fluororesin is particularly preferably used. By using the fluororesin, good low friction property and toner adhesion (non-adhesion) can be achieved.

  Specific examples of the fluororesin include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, polychlorotrifluoroethylene, chlorotrifluoroethylene-ethylene copolymer. And tetrafluoroethylene-vinylidene fluoride copolymer, polyvinylidene fluoride, and polyvinyl fluoride.

  Further, the resin forming the skin layer 4 is not particularly limited, but the conductivity (electric resistance) of the skin layer can be imparted or adjusted by adding a conductive agent. In this case, the conductive agent is not particularly limited, but various electronic conductive agents, various ionic conductive agents, and carbon are preferably used.

The addition amount of the conductive agent can be appropriately adjusted so that a desired resistance is obtained. In this case, the resistance of the skin layer 4 is preferably 1 × 10 ⁴ to 1 × 10 ¹² Ω · cm, particularly 1 × 10 ⁶ to 1 × 10 ⁸ Ω · cm. The addition amount of the conductive agent can be adjusted so as to achieve the rate, and the addition amount when carbon is used as the conductive agent is usually about 1 to 100 phr, particularly about 10 to 70 phr with respect to the base resin. The

  In addition, additives, such as a crosslinking agent, a thickener, a thixotropy imparting agent, and a structural viscosity imparting agent, can be added to the resin composition forming the skin layer 4 as necessary.

  The thickness of the skin layer 4 is not particularly limited, but is usually 1 to 30 μm, particularly 1 to 20 μm, and if it is less than 1 μm, the durability of the roller may be inferior, If it exceeds 20 μm, good surface properties may not be obtained, for example, the charging characteristics may be adversely affected or the surface may be wrinkled.

  The charging roller 10 manufactured according to the present embodiment is formed by forming the resistance adjustment layer 3 and the skin layer 4 on the elastic layer 2, but between the elastic layer 2 and the resistance adjustment layer 3 as necessary. Another layer may be interposed between the resistance adjustment layer 3 and the skin layer 4. For example, an adhesive layer having a thickness of about 1 to 50 μm can be provided between the elastic layer 2 and the resistance adjustment layer 3 in order to firmly bond both layers. In this case, the adhesive layer can be formed by applying a paint containing a resin material such as acrylic resin, urethane resin, acrylic urethane resin, polyester resin, polyamide resin or the like on the elastic layer 2 by a dipping method or the like. If necessary, a conductive agent and other additives can be added.

  Next, a method for manufacturing the charging roller 10 will be described. FIG. 2 is a process diagram showing a process of manufacturing the charging roller 10 having such a configuration. This manufacturing process includes a shaft supply process 21 for preparing and supplying the shaft 1, and coating the outer side in the radial direction of the shaft 1. An elastic layer forming step 22 for forming the elastic layer 2 by curing while coating the material, a resistance adjusting layer forming step 24 for forming the resistance adjusting layer 3 on the radially outer side of the elastic layer 2 in the same manner, and the like The charging roller 10 having the skin layer forming coating process 26 for forming the skin layer 4 on the outer side in the radial direction of the resistance adjusting layer 3 and finishing the last skin layer forming process 26 is transferred to the next process, for example, the inspection process. .

  When another layer is interposed between the elastic layer 2 and the resistance adjusting layer 3 or between the resistance adjusting layer 3 and the skin layer 4, the elastic layer 2 is interposed between the elastic layer forming step 22 and the resistance adjusting layer forming step 24. Alternatively, a step of forming another layer in the same manner between the resistance adjusting layer forming step 24 and the skin layer forming coating step 26 may be provided in the same manner. It can be formed by the same coating and curing method as the method for forming the layer 2.

  A method for forming each conductive layer will be described using the elastic layer 2 as an example. FIG. 3 is a partial cross-sectional view showing a coating apparatus for forming the elastic layer 2 by coating. The coating device 30 is for forming the elastic layer 2 by coating the outer peripheral surface of the shaft 1 serving as a base to form the elastic layer 2. A coating material storage container 31 provided so as to be in contact with each other, a heater 32 disposed coaxially with the container 31 for heating the coating material L painted on the outer peripheral surface of the shaft 1 from the outside in the radial direction, and the shaft 1. And a lifting platform 33 for moving up and down.

  The coating material container 31 and the heater 32 are fixed to a base 38, and the lifting platform 33 is provided so as to be moved up and down via a ball screw 36 by a lifting drive motor 35 fixed to the base 38. Further, above and below the shaft 1, even after the shaft 1 is removed from the lifting platform 33, it functions as a closing plug that closes a hole formed at the center of the blade 37 and prevents the coating material L from spilling.

  Here, the blade 37 is in contact with the shaft 1 and acts as a seal that prevents leakage of the liquid. In order to suppress vibration and wear when the shaft 1 is raised, the blade 37 is in surface contact with the shaft 1 at the abdomen of the blade. In addition, the effect of suppressing vibration and wear can be enhanced by forming the blade 37 with a fluorine-based resin.

  4 and 5 are diagrams for explaining the method of forming the elastic layer 2 using the coating apparatus 30 step by step. First, as shown in FIG. 4A, the shaft 33 and the spacers 34a and 34b are set on the lifting platform 33 at the position where the lifting platform 33 of the coating apparatus 30 is lowered. At this time, it is important that the spacer 34a located on the upper side of the shaft 1 is positioned at a height that makes contact with the blade 37 of the coating material storage container 31. In this state, the coating material is filled in the container. The liquid L does not leak due to the sealing action between the a and the blade 37.

  Next, as shown in FIG. 4B, when the lifting platform 33 is raised, the coating material L is painted on the outer peripheral surface of the shaft 1. At this time, if the material L has a high viscosity, a thick film layer can be formed. Further, since the coating material L immediately after being applied to the shaft 1 is sequentially heated and cured by the heater 32, there is no occurrence of sagging after coating, and the charging roller 10 being formed from the coating apparatus 1 is not yet formed. There is also no need to remove and temporarily cure in a separate step.

  As shown in FIG. 4C, the lifting platform 33 is raised to a height at which the lower spacer 34 b of the shaft 1 comes into contact with the blade 37 and stops. At this time, since the coating material L is applied over the entire length of the elastic layer extending region on the shaft 1 and the curing is completed, the elastic layer 2 is formed as shown in FIG. The charging roller 10 and the spacer 34a are removed from the lifting platform 33, and the charging roller 10 is discharged to the next step, for example, the resistance adjustment layer forming step 24 for forming the resistance adjustment layer 3.

  On the other hand, in the elastic layer forming step 22, next, as shown in FIG. 5B, the lifting platform 33 is lowered to the lower end. At this time, since the spacer 34b is held by the blade 37, the container It remains in the position 31 and prevents the coating material L from flowing out.

  Finally, as shown in FIG. 5 (c), the new shaft 1 supplied from the shaft supply step 21 is separated between the lowered elevator platform 33 and the spacer 34b remaining at the position of the container 31. The spacer 34c is set, and preparation for forming the elastic layer 2 of the next charging roller 10 is completed.

  Here, the height of the liquid of the coating material L accommodated in the container 31 can be made sufficiently low, so that a high-viscosity material that is difficult to maintain at a uniform concentration by other methods, for example, a viscosity of 10000 mPa · Even a layer having a density of s or more can be accommodated in a uniform concentration, so that the elastic layer 2 can be formed extremely uniformly in the length direction.

  The amount of the coating material L accommodated in the container 31 is preferably 1 to 5 charging rollers. When the amount is increased, the initial liquid level is increased, and the uniformity of the upper and lower concentrations is maintained. Becomes difficult.

  Thus, since the quantity of the coating material L accommodated in the container 31 is set small, the two-component curable coating material with a short pot life which is unsuitable with another method can also be used suitably.

  Further, if the coating material L is a solvent-free material having a so-called resin solid content of 100%, the concentration uniformity can be further enhanced.

  Further, by increasing the rising speed of the lifting / lowering platform 33 at the initial stage and the final stage, it is possible to form the crown-shaped charging roller 10 in which the central part in the axial direction swells.

  The method for forming the elastic layer 2 has been described above, but the same procedure can be applied to the resistance adjusting layer forming step 24 and the skin layer forming step 26 to form the resistance adjusting layer 3 and the skin layer 4. In the case of the resistance adjustment layer 3, a charging roller having an elastic layer formed thereon may be used, and in the case of the skin layer 4, a charging roller having a resistance adjustment layer formed thereon may be used.

  This method of forming a conductive roller can be used not only for a charging roller but also for a developing roller and a toner supply roller.

It is sectional drawing which shows the charging roller formed with the manufacturing method of embodiment of this invention. It is process drawing which shows the process of manufacturing a charging roller. It is a fragmentary sectional view which shows a coating device. It is explanatory drawing of the process of forming an elastic layer using a coating device. It is explanatory drawing of the process following FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft 2 Elastic layer 3 Resistance adjustment layer 4 Skin layer 10 Charging roller 21 Shaft supply process 22 Elastic layer formation process 24 Resistance adjustment layer formation process 26 Skin layer formation coating process 30 Coating apparatus 31 Coating material storage container 31
32 Heater 33 Lifting table 34a, 34b, 34c Spacer 35 Lifting drive motor 36 Ball screw 37 Blade 38 Base L Coating material

Claims (7)

When the conductive layer constituting the conductive roller is formed by applying a coating material on the outer peripheral surface of the substrate,
Conductive coating is performed by applying a coating material to a coating material container disposed outside the substrate in the radial direction and provided in contact with the entire circumference of the substrate by axially displacing the substrate through the bottom of the container. Manufacturing method of the adhesive roller.   The method for producing a conductive roller according to claim 1, wherein the viscosity of the coating material immediately before application is 10,000 mPa · s or more.   The method for producing a conductive roller according to claim 1, wherein the conductive layer is formed by applying a solvent-free coating material.   The method for producing a conductive roller according to claim 1, wherein the conductive layer is formed by applying a two-component curable coating material.   The method for manufacturing a conductive roller according to any one of claims 1 to 4, wherein a speed of relative displacement in the axial direction is changed during the displacement so that a central portion in the axial direction of the conductive roller is thicker than both ends.   The method for manufacturing a conductive roller according to any one of claims 1 to 5, wherein a coating-completed portion of the conductive layer is sequentially cured in the axial direction by a heater arranged coaxially with the coating material container.   The method for manufacturing a conductive roller according to claim 1, wherein the conductive layer is a base layer adjacent to a radially outer side of the shaft.

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