JP4476048B2 - Method for manufacturing elastic roller and charging roller - Google Patents

Description

  The present invention relates to a method for manufacturing an elastic roller such as a charging roller used in an electrostatic latent image process in a copying machine, a printer, or the like.

  Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, first, the surface of the photosensitive member is uniformly charged, and an image is projected onto the photosensitive member from the optical system to erase the charged portion. An electrostatic latent image is obtained by an electrostatic latent image process for forming a latent image, and then the electrostatic latent image is visualized as a toner image by adhesion of toner, and by transferring the toner image to a recording medium such as paper, The method of printing is taken.

  In order to charge the surface of the photosensitive member, a contact charging method for charging the surface of the photosensitive member by applying an elastic roller to the photosensitive member and applying a voltage to the elastic roller while rotating them is widely implemented. ing. The elastic roller used in this contact charging method is called a charging roller. For example, a material such as rubber or urethane foam is injected into a mold or extruded from an extruder to form an elastic layer around the shaft. A resistance adjustment layer is formed on the outer side of the elastic layer in the radial direction by adding a conductive agent to a resin such as urethane, acrylic urethane, acrylic ester, nylon, or a synthetic rubber such as NBR, and further adjusting the resistance. In addition, a resin layer in which a resin such as acrylic, urethane, or nylon is dissolved in an organic solvent or water is applied by a dipping method to form a skin layer (see, for example, Patent Document 1).

The elastic roller composed of a plurality of layers represented by the charging roller exemplified above has already been widely used in electrophotographic apparatuses such as copying machines and printers, and the recent central problem is that the cost of the elastic roller is greatly increased. For example, from the viewpoint of material cost, measures to reduce the material cost by reducing the diameter of the elastic roller are considered, and from the aspect of processing cost, equipment by developing a new manufacturing method is considered. Reductions in cost and processing man-hours have been studied. Among them, progress has been made in reducing the diameter of elastic rollers due to improvements in the materials of electrophotographic devices and elastic rollers. Is a problem because there is no manufacturing method that can replace the conventional manufacturing method.
JP 2003-131474 A

  The present invention has been made in view of such problems, and can reduce equipment costs, and in particular, a method for producing an elastic roller that can greatly reduce the cost of a small roller diameter. Is intended to provide.

(1) In the present invention, when producing an elastic roller comprising a plurality of layers including an elastic layer disposed around a shaft, all of these layers are formed by dip coating, and the elastic layer is formed of rubber. It is made of rubber formed by coagulating latex, a step of forming a coagulant layer made of a coagulant of a predetermined thickness around the shaft, and rubber latex is dip-coated around this coagulant layer And a step of coagulating latex, wherein the thickness of the elastic layer is adjusted by changing the thickness of the coagulant in the step of forming the coagulant layer .

  (2) In the present invention, in (1), each layer is sequentially laminated from the radially inner side to form each layer, and when at least one pair of two adjacent layers is laminated, the radially inner layer is dipped. An elastic roller manufacturing method comprising a step of forcibly drying this layer after painting.

  (3) The present invention differs from (1) or (2) in that each layer is formed by immersing an elastic roller in the middle of formation in a solution in a dip tank to produce an elastic roller of a plurality of sizes. It is a manufacturing method of the elastic roller which combines at least one of the said dip tanks with respect to size.

  (4) In the present invention, in any one of (1) to (3), at least one layer is formed by changing the thickness so that the central portion in the length direction is thicker than both ends. The method for producing an elastic roller according to any one of the above.

  (5) The present invention is the method for producing an elastic roller according to (4), wherein the elastic layer is formed by changing the thickness so that the central portion in the length direction is thicker than both ends.

  (6) The present invention is the method for producing an elastic roller according to any one of (1) to (5), wherein the elastic layer is formed by immersing an elastic roller being formed in a solution containing a thickener.

(7) according to item (1), the thickness of the shaft length direction central portion of the coagulant by thicker than both end portions, the elastic layer in the production method of finishing Ru elastic roller section crowned There is .

( 8 ) In the present invention, in ( 1 ) or ( 7 ), after the step of coagulating the rubber latex, the deposit formed by the salt generated in this step and the unreacted rubber latex is removed from the elastic roller. Provide a cleaning step to remove, and set the end position in the longitudinal direction of the coagulant layer before solidifying the rubber latex so that the shaft end surface of a predetermined length is exposed after removing the deposit. It is a manufacturing method of an elastic roller.

( 9 ) In the present invention, in ( 8 ), the coagulant layer is formed by immersing the shaft in a dip tank containing the coagulant, and a predetermined length portion of the coagulant adhering to the tip of the shaft is obtained. It is the manufacturing method of the elastic roller which sets the length direction edge part position of the said coagulant layer by wiping off.

( 10 ) In the present invention, in ( 8 ), the coagulant layer is formed by immersing the shaft in a dip tank containing the coagulant, and a predetermined length portion of the coagulant adhering to the tip of the shaft is obtained. It is the manufacturing method of the elastic roller which sets the length direction edge part position of the said coagulant layer by wash | cleaning and removing.

( 11 ) In the present invention, in ( 8 ), the coagulant layer is formed by immersing the shaft in a dip tank containing the coagulant, and a predetermined length portion of the shaft tip is masked prior to the immersion. This is a method for producing an elastic roller in which the position of the end portion in the lengthwise direction of the coagulant layer is set by masking with a tape and removing the masking tape after immersion.

( 12 ) The present invention, in ( 8 ), by forming a coagulant layer on the surface of the shaft by applying a coagulant coating liquid with a roll coater, and adjusting the coating area in roll coater coating, This is a method for manufacturing an elastic roller for setting the position of the end portion in the length direction of the coagulant layer.

( 13 ) The present invention is a charging roller formed by using the elastic roller manufacturing method according to any one of (1) to ( 12 ).

  According to the invention of (1), since all the layers are formed by dip coating, conventionally, an elastic layer is formed by extrusion molding or die molding in addition to dip coating equipment for forming a skin layer or the like. Whereas an extruding machine and a metal mold are required, it is possible to use only the dip coating equipment, and the equipment cost necessary for producing the elastic roller can be greatly reduced. In particular, in the case of a roller having a small roller diameter, the elastic roller can be formed with a small number of layers, which is more advantageous.

  According to the invention of (2), each layer is sequentially laminated from the inner side in the radial direction to form each layer, so that the layers can be efficiently laminated. In addition, when laminating two layers, it is necessary to dry the previously formed layer sufficiently, but according to this manufacturing method, the drying is forcibly dried using a drying facility or the like. Time can be shortened to improve productivity or to save space.

  According to the invention of (3), since at least one dip tank is also used with different sizes, many sizes can be manufactured with a small number of dip tanks, and the equipment cost and space can be further reduced.

  According to the invention of (4), at least one layer is formed by changing the thickness so that the central portion in the length direction is thicker than the both end portions, so that the elastic roller is convex at the central portion in the length direction. This can eliminate the non-uniformity in the longitudinal direction of the contact surface that occurs when an elastic roller without a crown shape is pressed against a photosensitive drum or the like. The performance that should be carried, for example, the electrical performance such as charging performance, can be made uniform in the length direction.

  According to the invention of (5), since the thick elastic layer is formed in the crown shape, when finishing the elastic roller having the same crown shape, the thin skin layer and the resistance adjustment layer are thickened at the center in the length direction. Compared to the case where it is made thinner, the influence on the electrical characteristic change due to the difference in thickness between the center and both ends can be reduced, and the performance that this elastic roller should carry can be further improved. , Uniform in the length direction.

  According to the invention of (6), the elastic layer is required to have a required thickness in order to exhibit its elastic effect. According to the method of manufacturing this elastic roller, the solution containing the thickener Since it has a process of immersing the elastic roller in the middle of formation in the dip tank, a thick layer can be formed by one immersion due to the effect of the thickener, and dip to form a layer of the same thickness By reducing the number of times of immersion in the tank, the equipment cost can be reduced and the productivity can be improved.

According to the invention of ( 1 ), according to this elastic roller manufacturing method, the elastic roller having the elastic layer made of rubber can be made inexpensive.

According to the invention of ( 1 ), it is known that the method of coagulating latex used for producing rubber gloves and the like is advantageous because a thick rubber layer can be formed by a single operation. However, according to this elastic roller manufacturing method, this latex coagulation method is used to form the rubber elastic layer, so when forming the elastic layer, the number of times of immersion in the dip tank is reduced to reduce equipment costs. And productivity can be improved.

According to the invention of ( 1 ), the thickness of the layer of the rubber latex formed when the coagulant dip-coated around the shaft reacts with the rubber latex emulsified in water to coagulate the rubber latex. Since the thickness of the rubber latex is adjusted by changing the thickness of the coagulant to determine the thickness of the elastic layer, the thickness of the elastic layer made of the rubber latex can be easily adjusted with high accuracy. There are also methods for adjusting the thickness of the rubber latex, such as adding a concentration distribution to the rubber latex solution and controlling the concentration distribution, or providing a distribution in the pH of the rubber latex solution to control the pH distribution. However, the method of changing the thickness of the coagulant can control the thickness of the elastic layer with higher accuracy than these methods.

According to the invention of ( 7 ), the distribution of the thickness of the coagulant in the shaft length direction is determined and the cross-sectional shape of the elastic layer is determined, so that the elastic layer can be accurately finished in a crown shape.

According to the invention of ( 8 ), in the cleaning step of removing the deposit formed of the salt generated in the rubber latex coagulation step and the unreacted rubber latex from the elastic roller, the predetermined amount is set after the deposit is removed. Before coagulating the rubber latex, the position of the coagulant layer in the lengthwise direction is set so that the surface of the shaft end of the length is exposed. In contrast to the method of removing the rubber latex, the shaft can be exposed very easily.

According to the invention of ( 9 ), the shaft is immersed in a dip tank containing a coagulant to form the coagulant layer, and a predetermined length portion of the coagulant adhering to the tip of the shaft is wiped off. The end position of the coagulant layer in the length direction can be easily set.

According to the invention of ( 10 ), the shaft is immersed in a dip tank that contains the coagulant to form the coagulant layer, and a predetermined length portion of the coagulant adhering to the tip of the shaft is washed. Since it is removed, the end position in the length direction of the coagulant layer can be set easily.

According to the invention of ( 11 ), the coagulant layer is formed by immersing the shaft in a dip tank containing the coagulant, and a predetermined length portion of the shaft tip is masked with a masking tape prior to the immersion. Since the masking tape is peeled off after the immersion, the end position of the coagulant layer in the length direction can be accurately set.

  The reason for using a masking tape with almost no thickness instead of a masking cap as a tool for masking the shaft is that if each end of the shaft is masked with a thick masking cap, the masking cap A wide range of the elastic layer adjacent to the axial center side of the film becomes thicker than the axial center side thickness. By using a masking tape that has almost no thickness instead of the masking cap, it is uniform over the entire axial length. This is because an elastic layer with a sufficient thickness can be formed.

According to the invention of ( 12 ), since the coagulant layer is formed on the shaft surface by coating the coagulant coating liquid with a roll coater, this is also precisely the longitudinal end of the coagulant layer. The part position can be set.

According to the invention of ( 13 ), since it is formed by the above-described elastic roller manufacturing method, an extruder or a mold can be dispensed with, which is advantageous in terms of cost reduction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the elastic roller is an example of a charging roller used for charging the surface of the photosensitive member, FIG. 1 is a cross-sectional view of the charging roller, and FIG. 2 is a process for manufacturing the charging roller. It is process drawing which shows the flow of this. The charging roller 10 includes a shaft 1, an elastic layer 2 disposed around the shaft 1, a skin layer 4 that forms a roller peripheral surface, and a resistance adjustment layer provided between the elastic layer 2 and the skin layer 4. It consists of three. 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, but 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 thickening agent is added to the elastic layer 2 to thicken the coating film formed by one immersion. 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 0.3 to 10 mm, particularly 0.2 to It is preferable to be about 3 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 An aqueous resin such as urethane resin and acrylic resin is 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. As this ionic conductive material, tetradecammonium, tetrabutylammonium, dodecyltrimethylammonium such as lauryltrimethylammonium, octadecyltrimethylammonium such as hexadecyltrimethylammonium, stearyltrimethylammonium, benzyltrimethylammonium, benzyltriethylammonium, benzyltributylammonium, modified Ammonium perchlorate such as aliphatic dimethylethyl ammonium, 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, it 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 added to the resistance adjusting layer 3. For example, an oxazoline-based, epoxy-based, melamine-based, guanamine-based, isocyanate-based, or phenol-based crosslinking agent can be added. 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 manufactured according to this 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.

  FIG. 2 is a process diagram showing a process of manufacturing the charging roller 10 having such a configuration, and a method of manufacturing the charging roller 10 will be described with reference to FIG. This manufacturing process includes a shaft supply process 21 for preparing and supplying the shaft 1, an elastic layer dip coating process 22 for dip coating the elastic layer 2 on the shaft 1, an elastic layer drying process 23 for forcibly drying the elastic layer 2, A resistance adjustment layer dip coating step 24 for dip-coating the resistance adjustment layer 3 on the radially outer side of the elastic layer 2, a resistance adjustment layer drying step 25 for forcibly drying the resistance adjustment layer 3, and a skin layer on the radially outer side of the resistance adjustment layer 3 4 is a dip coating process 26 for dip coating, and a skin layer drying process 27 for forcibly drying the skin layer 4, and the charging roller 10 having finished the last skin layer drying process 27 is subjected to the following process, for example, Moved to inspection process.

  When another layer is interposed between the elastic layer 2 and the resistance adjustment layer 3 or between the resistance adjustment layer 3 and the skin layer 4, it is between the elastic layer drying step 23 and the resistance adjustment layer dip coating step 25. Alternatively, a step of dip-coating the other layer and a step of drying the subsequent dip-coated layer may be provided between the resistance adjustment layer drying step 25 and the skin layer dip coating step 26. The charging roller 10 can be formed by repeating dip coating and drying in order from the inner layer in the direction.

  To form these layers by dip coating, industrially, usually, 30 or more rollers are suspended vertically on a hanger, and the rollers are simultaneously applied to the solution of the material constituting each layer. A method of dipping, pulling up and drying by blowing is used, but in this case, it is necessary to strictly control the temperature of the paint and the roller to be applied at the time of coating and the blowing condition for drying. Is important to get.

  Moreover, as equipment for realizing the above steps, a dip tank filled with a solution for dip-coating each layer, a blower for drying the dip layer, and the temperature of the rollers being formed in each step A temperature control tank for control and a transport conveyor for transporting the rollers are required. In the case of producing a plurality of charging rollers 10 of a plurality of sizes in order, it is preferable to use the above equipment such as a dip tank in different sizes in order to reduce the equipment cost.

  The solvent for preparing the solution may be appropriately selected according to the type of material constituting each layer. For example, when a fluororesin is used as the base resin for the skin layer 4, methyl ethyl ketone ( MEK), methyl isobutyl ketone (MIBK), toluene, xylene and the like are preferably used.

Here, the adjustment method of the coating material dissolved in the solution to be dipped in the elastic layer dip coating step 22 will be exemplified below.
(A) Example of polyurethane (solid type) Water-dispersed urethane resin (IZELUX S-4040N: manufactured by Hodogaya Chemical Co., Ltd.): 100 parts by mass, carbon black (MA100: manufactured by Mitsubishi Chemical Corporation): 10 parts by mass , And thickener (SN thickener A-815: manufactured by San Nopco Co., Ltd.): 1 part by mass is mixed with a stirring blade to prepare a coating material.

(B) Example of polyurethane (foam type) Water-dispersed urethane resin (IZELAX S-4040N: manufactured by Hodogaya Chemical Co., Ltd.): 100 parts by mass, carbon black (MA100: manufactured by Mitsubishi Chemical Corporation): 10 parts by mass And 3 parts by mass of a foam stabilizer (FR14: manufactured by Kao Corporation) are mixed with a high-speed foaming stirrer to prepare a foam paint having a foam density of 0.4 g / cm ³ .

(C) Examples of rubber (solid type) Rubber latex (JSR0561: manufactured by JSR Corporation): 100 parts by mass, carbon black (MA100: manufactured by Mitsubishi Chemical Corporation): 10 parts by mass, colloidal sulfur (colloidal sulfur: Hosoi) Chemical Industry Co., Ltd.): 2 parts by mass, and thickener (SN thickener A-815: San Nopco Co., Ltd.): 1 part by mass are mixed with a stirring blade.

(D) Example of rubber (foam type) Rubber latex (JSR0561: manufactured by JSR Corporation): 100 parts by mass, carbon black (MA100: manufactured by Mitsubishi Chemical Corporation): 10 parts by mass, colloidal sulfur (colloidal sulfur: Hosoi) Chemical Industry Co., Ltd.): 2 parts by mass and foaming agent (FR25: Kao Co., Ltd.): 0.5 parts by mass were mixed with a high-speed foaming stirrer, and the foam density was 0.4 g / cm ³ . Adjust foam paint.

  Further, the following is an example in the case where a latex coagulation liquid is used to more easily form a thick layer. In this case, the elastic layer dip coating process 22 shown in FIG. 2 is changed into five processes shown in FIG. It replaces and the elastic layer 2 is formed. That is, first, in the latex undercoat step 22a, the shaft 1 whose both ends are masked with the masking tape is immersed in a latex dip tank that contains the latex liquid emulsified in water, and latex is applied to the peripheral surface of the shaft 1. After the undercoating, in the coagulant dip coating step 22b, the coagulant is dip-coated by immersing the undercoated shaft 1 in a coagulation liquid dip tank containing the coagulant solution to form a coagulant layer. Here, the undercoat latex functions as an adhesive for adhering the coagulation liquid to the shaft 1.

  After air is applied to the shaft 1 on which the coagulant layer is formed and dried at room temperature, the masking tape is peeled off from the shaft 1 to expose the tip of the shaft 1, and then the latex dip coating step 22c applies this to the latex. Immerse in a dip tank. At this time, the acidic coagulant and the alkali latex cause an acid-alkali reaction, and the latex is gelled and coagulated with the acid-alkali reaction. Thus, in this latex coagulation method, since the elastic layer 2 is formed by reaction with the coagulant, it is possible to form the cross-sectional shape of the coagulant layer formed around the shaft 1 with high accuracy. This is important in forming a flexible elastic layer, and conversely, the dimensions of the elastic layer can be adjusted by changing the thickness and cross-sectional dimensions of the coagulant layer. The thickness and cross-sectional dimensions of the coagulant layer can be changed by changing the concentration of the coagulant or changing dipping conditions such as the pulling speed when pulling up the roller from the dip tank.

  After the latex dip coating step 22c, in order to remove the water generated by the acid-alkali reaction, in the low-temperature drying step 22d, the temperature of the roller being formed is kept at, for example, about 40 ° C. In order to remove the salt generated in step 2, the washing step 22e is washed with water having a low salt concentration. If this salt is not removed, it will remain in the roller as a foreign substance and will deposit on the roller surface during use, causing contamination of the photoreceptor.

  FIG. 4 is a cross-sectional view showing the tip of the shaft 1 before and after the cleaning step 22e. FIG. 4 (a) shows a state before cleaning, and FIG. 4 (b) shows a result after cleaning. In this cleaning step 22e, in addition to salt, unreacted latex is also removed, but at the tip of the shaft 1 before cleaning, the coagulation reaction has been completed outside the coagulant layer 15 extending around the shaft 1. The latex layer 16 is formed as shown in FIG. 4A. This latex layer is formed not only on the outer side in the radial direction of the coagulant layer 15 but also on the outer side in the axial direction from the end of the coagulant layer 15. Further, salt and unreacted latex 17 are adhered to the outer side of the latex layer 16 after the coagulation reaction and the surface of the shaft 1.

  In the cleaning step 22e, the salt and unreacted latex 17 are removed to leave only the latex layer 16 that has undergone the coagulation reaction and to expose the tip of the shaft 1 as shown in FIG. 4 (b). Can do. The exposed length Da of the shaft portion can be determined by setting the position of the coagulant layer in the longitudinal direction, for example, the position of Db from the end of the shaft 1. In this case, the setting is made according to the attachment position of the masking tape.

  In addition to the masking tape method, the coagulant is dip-coated without applying the masking tape, and after coating, the length of the end of the coagulant layer in the longitudinal direction is a predetermined length. It can also be carried out by washing or wiping off.

  Further, as another example of the method of setting the position of the end portion in the length direction of the coagulant layer, instead of dip coating in which the tip portion of the shaft 1 is necessarily coated, a coating in which the coagulant is melted with a roll coater A method of coating the surface of the shaft with the liquid can also be used. In this case, the position of the coagulant layer in the longitudinal direction can be set by setting the coating region at both ends in the longitudinal direction.

  After the cleaning step 22e, this roller is transferred to the elastic layer drying step 23 to form the elastic layer 2. In the elastic layer drying step 23, latex is vulcanized in addition to evaporating moisture. Therefore, for example, drying is performed at a high temperature of about 70 to 80 degrees.

  Examples of the adjustment of the paint used in the latex dip coating step 22c include the same ones as shown in the above (C) and (D). In this case, the latex coagulant solution in the coagulant dip coating step 22b As an example, a coagulant (coal latex 93: manufactured by Kawaguchi Chemical Industry Co., Ltd.): 50 parts by mass and methanol: 50 parts by mass are mixed with a stirring blade to adjust a coagulation liquid.

  In the above blending examples, carbon black is used as the conductive agent, but there is no problem even if an ionic conductive agent is used instead.

  When forming a thick elastic layer, it is preferable from the viewpoint of productivity that a coating amount as thick as possible can be obtained by one dip coating. For this purpose, for example, a thickener in which cellulose is dispersed in a paint Is formed by immersing the shaft 1 in a solution in which the paint is dissolved, or in the case where the elastic layer is made of rubber, the latex is coagulated as shown in the above example. A thick adhesion amount can be obtained.

  Regarding the management of the paint temperature, it is preferable to provide a heater and a temperature sensor in the dip tank, and keep the paint temperature at the time of application substantially constant in the range of 25 to 35 ° C., more specifically, the paint within the above temperature range. It is preferable to apply the paint by dipping while maintaining the temperature within a range of ± 1 ° C. Regarding the temperature control of the rollers, it is preferable to adjust all the rollers just before dipping in the paint to a substantially uniform temperature by a heater or warm air, and more specifically, the rollers are heated to a temperature of 30 ° C. or more. The temperature variation of each roller is preferably ± 1 ° C. of the average temperature of all the rollers. Furthermore, with respect to the air blowing conditions, it is preferable to dry the plurality of rollers suspended on the hanger by blowing air from below to above. It is preferable that the variation is within ± 0.1 m / s. By performing the paint temperature management, the roller temperature management, and the air blowing condition management, the resistance adjusting layer 3, the skin layer 4, and the adhesion can be satisfactorily produced without causing dripping of the paint, filming, or generation of bubbles. An agent layer or the like can be formed.

  FIG. 5 is a side view of the dip tank showing a state in the middle of forming the elastic layer by pulling up the shaft 1 from the solution, and FIG. 6 is a cross-sectional view showing the charging roller 20 having a crown shape. It is important for the charging roller 20 to form a uniform contact surface in the length direction when being pressed against the photosensitive drum, and therefore, it is preferable that the charging roller 20 has a crown shape in which the central portion in the length direction has a larger diameter than the end portion. However, as shown in FIG. 5, the center of the elastic layer 12 in the longitudinal direction is changed by changing the pulling speed when pulling up the shaft 1 suspended from the hanger 8 from the solution 6 in the dip tank 9 according to the pulling position. The crown-shaped elastic roller 20 can be formed by controlling the adhesion amount of the elastic layer 7 in the middle of formation so as to be thick at the end and thin at the end. In this case, it is not necessary to change the thickness of the resistance adjustment layer 13 and the skin layer 14 in the length direction, and if the resistance adjustment layer 13 or the skin layer 14 is thick at the center in the length direction, it is thin at the end. Thus, when the crown-shaped elastic roller 20 is formed, it is possible to prevent variations in the electrical characteristics in the length direction that may occur because the layers 13 and 14 are thin layers. .

  When the elastic layer 12 is formed by the latex coagulation method, the cross-sectional shape of the elastic layer is determined by the cross-sectional shape of the coagulant as described above, and therefore, the cross-section of the coagulant must be formed in a crown shape. When dipping the coagulant, the pulling speed is changed as described above.

  As described above, the elastic roller manufacturing method has been described using the charging rollers 10 and 20 as an example. However, for other elastic rollers, a method of forming all layers by dip coating can be used, and the same effect can be obtained. Can do.

  This elastic roller manufacturing method can be applied to a roller made of a plurality of layers and made of high-precision rubber or resin used in an electrophotographic apparatus, in addition to a charging roller.

It is sectional drawing of the charging roller used as the typical example of the elastic roller formed by the manufacturing method of embodiment which concerns on this invention. It is process drawing which shows the flow of the process which manufactures a charging roller. It is a partial process figure at the time of forming an elastic layer by the latex coagulation method. It is sectional drawing of the shaft front-end | tip part before and behind a washing | cleaning process. It is a side view of the dip tank which shows the state in the middle of pulling up a shaft from a solution and forming an elastic layer. It is sectional drawing which shows the charging roller which has a crown shape.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft 2, 12 Elastic layer 3, 13 Resistance adjustment layer 4, 14 Skin layer 6 Solution 7 Elastic layer in the middle of formation 8 Hanger 9 Dip layer 10 Charging roller 15 Coagulant layer 16 Coagulated latex layer 17 Unreacted latex 20 Charging roller 21 Shaft supply process 22 Elastic layer dip coating process 22a Latex undercoating process 22b Coagulant dip coating process 22c Latex dip coating process 22d Low temperature drying process 22e Cleaning process 23 Elastic layer drying process 24 Resistance adjustment layer dip coating process 25 Resistance adjustment Layer drying process 26 Skin layer dip coating process 27 Skin layer drying process

Claims (13)

In producing an elastic roller comprising a plurality of layers, including an elastic layer disposed around the shaft,
All of these layers are formed by dip coating ,
The elastic layer is made of rubber formed by coagulating rubber latex;
A coagulant layer comprising a step of forming a coagulant layer made of a coagulant of a predetermined thickness around the shaft and a step of dip-coating rubber latex around the coagulant layer to coagulate the rubber latex. A method for producing an elastic roller, wherein the thickness of the elastic layer is adjusted by changing the thickness of the coagulant in the step of forming .   Each layer is sequentially laminated from the radially inner side to form each layer, and at the time of laminating at least one pair of two adjacent layers, a step of forcibly drying the layer after dip coating the radially inner layer is provided. The method for producing an elastic roller according to claim 1.   Each layer is formed by immersing an elastic roller in the middle of formation in a solution in a dip tank, and when producing a plurality of sizes of elastic rollers, at least one of the dip tanks is also used for different sizes. The manufacturing method of the elastic roller of Claim 1 or 2.   The method for producing an elastic roller according to any one of claims 1 to 3, wherein the at least one layer is formed by changing the thickness so that a central portion in the length direction is thicker than both end portions.   The method for producing an elastic roller according to claim 4, wherein the elastic layer is formed by changing the thickness so that the central portion in the length direction is thicker than both ends.   The method for producing an elastic roller according to claim 1, wherein the elastic layer is formed by immersing an elastic roller in the middle of formation in a solution containing a thickener. By the shaft length thickness direction center portion of the coagulant thicker than both end portions, the manufacturing method of the elastic roller according to claim 1 to finish the elastic layer in cross section crowned. After the step of coagulating the rubber latex, there is provided a cleaning step for removing the salt produced in this step and the deposit made of unreacted rubber latex from the elastic roller, and after removing the deposit, a predetermined process is performed. The method for producing an elastic roller according to claim 1 or 7 , wherein the end position in the length direction of the coagulant layer is set before the rubber latex is coagulated so that the shaft end surface of the length is exposed. The coagulant layer is formed by immersing the shaft in a dip tank containing the coagulant, and the length of the coagulant layer is removed by wiping off a predetermined length of the coagulant adhering to the tip of the shaft. The manufacturing method of the elastic roller of Claim 8 which sets a direction edge part position. The coagulant is formed by immersing the shaft in a dip tank containing the coagulant to form the coagulant layer, and washing and removing a predetermined length portion of the coagulant adhering to the tip of the shaft. The elastic roller manufacturing method according to claim 8 , wherein the position of the end portion in the length direction of the layer is set. The shaft is immersed in a dip tank containing a coagulant to form the coagulant layer. Prior to this immersion, a predetermined length of the shaft tip is masked with a masking tape, and after the immersion, the masking tape is peeled off. The manufacturing method of the elastic roller of Claim 8 which sets the length direction edge part position of the said coagulant layer by this. The coagulant coating liquid is applied to the shaft surface with a roll coater to form the coagulant layer, and by adjusting the coating area in the roll coater coating, the end position of the coagulant layer in the length direction is adjusted. The manufacturing method of the elastic roller of Claim 8 to set. Charging roller formed is formed using the manufacturing method of the elastic roller according to any one of claims 1 to 12.

Images