JP2006201505A - Developing roller and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller free from damage to a metal core and also free from an image defect caused by rotation failure or the like, by increasing the hardness of plating applied to the surface of a metal core, and to provide a production method therefor. <P>SOLUTION: In the developing roller in which elastic layer formed from a conductive silicone rubber and a covering layer are disposed in that order on the circumference of a metal core, the surface of the metal core is coated with plating containing at least phosphorus and nickel formed through non-electrolyzed nickel-phosphorus plating. The coating of plating contains a 1-phosphide 3-nickel (Ni<SB>3</SB>P). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing roller in an image forming apparatus employing an electrophotographic system such as a printer, a facsimile machine, and a copying machine, and a manufacturing method thereof.

  In recent years, OA equipment such as copying machines and printers has been improved in image quality, and accordingly, a developer having an elastic layer as a developer carrying member in a development process for visualizing an electrostatic latent image on a photoreceptor with toner. There has been proposed a contact development method in which development is performed by using a support member and uniformly pressing the photosensitive member. In this contact development method, the developer carrying member has an elastic layer made of an elastic material in order to ensure a uniform pressure contact width to the photoconductor, and a toner image is applied to the photoconductor by applying a voltage. Therefore, uniform conductivity and leak resistance are required.

  Therefore, for example, an elastic layer in which an electronic conductive agent or an ionic conductive agent is dispersed and adjusted to a desired resistance value is formed on a conductive support, and wear resistance, toner charging property, and toner transportability are provided on the outer periphery thereof. In order to obtain the coating layer, a coating layer made of a coating material to which a resin such as nylon or urethane and rough particles for ensuring proper surface roughness and a conductive agent for ensuring conductivity is added is often provided. .

  Now, these developer-carrying members are used, for example, by providing portions where the shafts are exposed at both ends in order to be fixed and rotated on the bearing portions of the apparatus main body or the cartridge main body.

  The shaft body is usually plated. There are many platings such as brass plating and zinc plating. Among them, electroless nickel plating is generally used. One of the characteristics of electroless nickel plating is that the elements mixed in the coating differ depending on the type of reducing agent in the plating solution. For example, when a hypophosphite compound is used as the reducing agent, phosphorus or borohydride In the compound, boron is mixed. On the other hand, it may be hardly mixed like hydrazine and formalin. Such an electroless nickel plating method is also called chemical plating, and is a method based on a pure chemical reaction in which metal ions are reduced and deposited by a reducing agent contained in the plating solution. Compared with the electrolytic nickel plating method using electricity, the plating method has the advantage that the thickness of the plating film is uniform, high dimensional accuracy is obtained, and pinholes are less likely to occur, so that the corrosion resistance is excellent.

  As described above, the developer carrying member ensures a uniform pressure contact width to the photosensitive member and carries a uniform amount of toner, but the exposed shafts at both ends of the developer carrying member are scratched. As a result, there is a problem in that the shaft member causes a rotation failure, and the toner conveyance amount is locally non-uniform and appears as an image defect. Even if the image does not appear as an image defect at the start of use, if the shaft body is scratched, depending on the use environment of the apparatus main body or the cartridge main body, the shaft body may rust, resulting in an image defect.

In the prior art, the core metal subjected to electroless nickel plating is inactivated by chromic acid treatment or heat treatment (surface oxidation) to improve the adhesion of the rubber material. (Patent Document 1, Non-Patent Document 1))
This method can improve adhesion in surface oxidation by heat treatment, but cannot increase the hardness of the plating layer. In addition, the chromic acid treatment is not preferable from an environmental viewpoint.

In another prior art, in order to prevent the shaft body from being scratched, a rubber roll is formed on the shaft body, and then unnecessary rubber is removed, so that the rubber is removed without contact with the shaft body by suction force. A method has been proposed. (Patent Document 2)
Although this method depends on the adhesive strength of the rubber to the shaft body, unnecessary rubber may remain or adhesive for bonding the rubber and shaft body may remain. The adhesive strength is relatively weak and is limited to those having good peelability.

As another method, in order to remove unnecessary rubber, a method has been proposed in which ultrahigh pressure water is sprayed to remove unnecessary rubber so that the shaft body is not damaged. (Patent Document 3)
In this method, when removing the rubber part at the end of the unnecessary shaft body, the rubber part of the required part and the shaft body are often damaged, and the finished rubber roll has the rubber end side away from the shaft body. It peels and becomes a so-called trumpet shape in which the rubber diameter at the end becomes thick. Moreover, it can be used only when the roller has fast reversibility with respect to water.
Japanese Patent Publication No. 7-74056, (page 2) JP 2004-195625 A, (page 2) JP-A-8-174500, (2nd page) Toshio Okamura, Shigemitsu Kawagishi, Tokuzo Kobe, Osamu Takano; “Application of Electroless Plating”, p170-173, (1991), Tsuji Shoten

The object of the present invention has been made in view of the above-mentioned problems, and by forming a plating film containing Ni ₃ P on the outer periphery of the core metal and increasing the hardness of the plating applied to the core metal surface, the core metal It is an object of the present invention to provide a developing roller having no scratches and no image defects caused by rotation failure, and a method for manufacturing the same.

In the present invention that has solved the above problems, an elastic layer formed of conductive silicone rubber and a coating layer are formed in order from the inner peripheral side on the outer periphery of the core metal (elasticity from the inner peripheral side toward the outer peripheral side). In the developing roller in which the layer and the coating layer are formed in this order,
The present invention relates to a developing roller characterized in that the surface of the metal core is coated with a plating containing at least phosphorus and nickel, and the plating film contains trinickel monophosphide (Ni ₃ P).

The content of trinickel monophosphide (Ni ₃ P) in the plating film is preferably 3% by mass to 70% by mass.

The present invention also includes a step of forming a plating film containing at least phosphorus and nickel on the surface of the core metal by electroless nickel-phosphorus plating,
Forming a nickel triphosphide (Ni ₃ P) in the plating film by heat-treating the plating film at 200 ° C. to 500 ° C .;
The core metal on which the trinickel monophosphide (Ni ₃ P) is formed is arranged in a metal cylindrical mold so as to be concentric with the cylindrical mold, and in the gap between the core metal and the cylindrical mold Injecting a conductive silicone rubber material and thermosetting it to form an elastic layer made of conductive silicone rubber on the core;
Forming a coating layer on the outer periphery of the elastic layer;
The present invention relates to a method for manufacturing a developing roller.

It is preferable that the time from the formation of the plating film to the step of forming trinickel monophosphide (Ni ₃ P) in the plating film by the heat treatment is within 24 hours.
The heat treatment is preferably performed in an inert atmosphere or a reducing atmosphere.

  As described above, according to the present invention, by increasing the hardness of the plating applied to the surface of the core metal, it is possible to provide a developing roller having no scratches on the core metal and no image defects due to rotation failure and the like, and a method for manufacturing the same. Made possible.

As described above, according to the present invention, in the developing roller formed on the outer periphery of the core metal in the order of the elastic layer formed of the conductive silicone rubber and the coating layer from the inner periphery side, the surface of the core metal has no surface. The developing roller is formed by electrolytic nickel-phosphorus plating and is coated with a plating containing at least phosphorus and nickel, and the plating film contains trinickel monophosphide (Ni ₃ P).

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. In addition, “parts” in the embodiments, examples and comparative examples of the present invention indicate parts by mass.

  FIG. 1 shows an outline of one embodiment of the developing roller of the present invention. (A) is a schematic sectional view along the axis of the developing roller, and (b) is a schematic section when the developing roller is viewed from the axial direction. The figure is shown. In the developing roller of the embodiment shown in this figure, an elastic layer 1b is formed on a metal core 1a, and a coating layer 1c is further provided on the outer periphery thereof.

1) Core Bar In the present invention, a shaft body (core bar) whose surface is plated with electroless nickel-phosphorus is used. The shaft body is not particularly limited, and can be used even if it is hollow or solid. Further, the material is not particularly limited, and is made of iron or steel, for example, metal such as iron, aluminum, titanium, copper and nickel, or alloy such as stainless steel, duralumin, brass and bronze containing these metals. In addition, a conventionally known one can be used for manufacturing a developing roller.

  The method for plating the electroless nickel-phosphorous plating film applied to the shaft body is not particularly limited, and is performed by a conventionally known electroless nickel-phosphorous plating method. The electroless nickel-phosphorous plating method is a particularly preferable plating method for a shaft body for a rubber roller from the viewpoint that the thickness of the plating film is uniform, high dimensional accuracy is obtained, and pinholes are less likely to be generated, so that the corrosion resistance is excellent.

In the present invention, the electroless nickel-phosphorous plating film containing trinickel monophosphide (Ni ₃ P) is used. Usually, the composition of the plating film is mainly composed of nickel and phosphorus, and the phosphorus in the film is 0.5 mass% to 21 mass% depending on conditions such as the concentration, composition, pH, plating temperature and time of the plating solution. The content can be varied up to%.

  As a preferable plating solution for changing the phosphorus concentration in the film to a suitable range, it is preferable to set the pH in the acidic region. About plating temperature, the range of 40 to 90 degreeC is preferable. When electroless nickel-phosphorus plating is performed under these conditions, the resulting film thickness is 6 μm or less.

The higher the phosphorus content, the better the scratch resistance and corrosion resistance. However, if it is too much, the film may become brittle and is practical at a concentration of 21% by mass or less. On the other hand, phosphorus in the film reacts with nickel by applying energy and crystallizes to form trinickel monophosphide (Ni ₃ P) (Non-patent Document 1). Since trinickel phosphide (Ni ₃ P) has the properties of an interstitial compound, it has excellent scratch resistance and corrosion resistance, and has no adverse effect on conductivity.

The effect of the present invention can be obtained if at least trinickel monophosphide (Ni ₃ P) is contained in the electroless nickel-phosphorous plating film applied to the shaft body. However, when the phosphorus content is less than 0.5% by mass, the nickel component and the phosphorus component are difficult to react during plating. Accordingly, a considerable amount of energy is required to obtain the amount of trinickel monophosphide (Ni ₃ P) necessary for exhibiting the effects of the present invention, which is strict in terms of cost and conditions.

On the other hand, when the phosphorus content is 0.5% by mass or more, the plating film is deposited in an amorphous state, so that the reaction between the nickel component and the phosphorus component is likely to proceed, and the amount necessary for exhibiting the effects of the present invention. It is possible to easily form trinickel monophosphide (Ni ₃ P). Therefore, if the phosphorus content in the plating film is 0.5% by mass or more, the excellent effect of the present invention can be obtained, but if it exceeds 21% by mass, the original characteristics of the plating are lost and the film becomes brittle. Since peeling of the plating film is likely to occur, the corrosion resistance and scratch resistance are reduced. From the above viewpoint, the electroless nickel-phosphorous plating applied to the shaft of the developing roller of the present invention preferably has a phosphorus content in the plating film of 0.5% to 21% by mass, and 8% to 16%. The mass% is more preferable.

The effect of the present invention is to first activate phosphorus in the electroless nickel-phosphorus film to form trinickel monophosphide (Ni ₃ P). The method for forming trinickel monophosphide (Ni ₃ P) is not particularly limited as long as it can provide the amount of heat necessary to activate and crystallize phosphorus in the plating film. For example, conventionally known methods such as a hot stove, induction heating, high frequency and laser can be used. However, when the method is electric heating such as induction heating, it is required that the shaft body serving as the plating substrate is a conductive metal. It should be noted that the degree of phosphorus in the plating film and the formation of Ni and crystals in the form of Ni ₃ P depend on the conditions for activating phosphorus. Depending on the conditions, all of phosphorus forms Ni ₃ P or part of it forms Ni ₃ P.

Heating can be performed in an inert atmosphere or a reducing atmosphere. Specifically, it is preferably performed in a reducing atmosphere (hydrogen gas or the like) or an inert gas (argon or nitrogen gas or the like) atmosphere. When heating is performed in an inert atmosphere or a reducing atmosphere, the oxygen concentration in the atmosphere can be made lower than that in air, so that crystallization of trinickel monophosphide (Ni ₃ P) can be more effectively performed. As specific flow rates of the inert gas atmosphere and the reducing atmosphere, it is sufficient that the oxygen concentration during the heat treatment is lower than that of air.

If the heating temperature is 200 ° C. or higher, the activation of phosphorus in the plating film proceeds, and the crystallization of trinickel monophosphide (Ni ₃ P) proceeds better. For example, when the shaft body is iron, the shaft body may be deformed and cannot be used as the shaft body of the developing roller when the shaft body exceeds 500 ° C. For this reason, 200 to 500 degreeC is used preferably as heating temperature. Moreover, since work management will generally be difficult under high temperature conditions, 200 ° C. to 400 ° C. is more preferable.

The time from the completion of the formation of the plating film on the shaft to the heat treatment is preferably within 24 hours, and more preferably within 1 hour. This is because if the shaft body on which the plating film is formed is left in the air, the surface of the plating film gradually oxidizes, which hinders the formation of trinickel monophosphide (Ni ₃ P). It is. The completion of the formation of the plating film as used herein refers to a case where the plating film is formed with a plating solution, dried through a rinsing step and the like. In addition, the heating time is preferably 30 minutes or more, although it varies depending on the heating temperature.

The content of trinickel monophosphide (Ni ₃ P) in the plating film is preferably 3% by mass to 70% by mass. The upper limit is the state in which all phosphorus in the plating film has reacted to become trinickel monophosphide (Ni ₃ P). When the phosphorus content in the plating film is 21% by weight, the nickel triphosphide in the plating film (Ni ₃ P) is the upper limit of approximately 70% by mass. In addition, the lower limit is that when the phosphorus content in the plating film is 0.5 mass%, the content of trinickel phosphide (Ni ₃ P) in the plating film is approximately 3 mass% or more. The effect was recognized. In order to set the content of trinickel monophosphide (Ni ₃ P) in the plating film to 3% by mass to 70% by mass, the phosphorus content in the film at the time of film formation can be changed, or nickel (Ni ₃ P) heating temperature during forming may be adjusted. Moreover, when the content of trinickel monophosphide (Ni ₃ P) in the plating film is 3% by mass to 70% by mass, a metal core having more excellent scratch resistance can be obtained.

2) Elastic layer Conductive silicone rubber is used for the elastic layer 1b. Silicone rubbers may be used alone or in combination. In order to impart conductivity to the silicone rubber, a conductive agent having an electron conduction mechanism (carbon black, graphite, conductive metal oxide, copper, aluminum, nickel, iron powder, etc.) or an ionic conductive agent (alkali metal salt and What added ammonium salt), conductive rubber, etc. can be used suitably. In this case, two or more conductive agents may be used in combination. The addition amount of the conductive agent is usually 2 to 20 parts with respect to 100 parts of the silicone rubber material. In consideration of hardness and compression set, it is preferable to use an addition reaction type conductive silicone rubber for the elastic layer.

  The thickness of the elastic layer is usually preferably 1 to 6 mm. The material of the elastic layer that can be used in the present invention is obtained from a step of injecting a material using a mold and thermosetting it. The elastic layer is formed by using a metal core with a plating coating placed concentrically in a metal cylindrical mold, and both ends are supported by a metal piece with a material inlet. The conductive silicone rubber material is injected into the gap formed by the cored bar and the cylindrical shape from either one of the longitudinal directions and thermally cured, and then removed from the mold to form an elastic layer made of conductive silicone rubber. To do. The viscosity of the conductive silicone rubber material is preferably 50 to 500 Pa · s at 25 ° C. Moreover, although the temperature of thermosetting is based also on the kind of material, it is preferable that it is 105-130 degreeC. At this time, the metal piece is in contact with the core in order to stably support the core in the mold, but when the metal piece is assembled and removed, the metal piece is inserted into and removed from the core. Depending on how the angle is adjusted, the mandrel is often damaged. For the hardness of the core metal, it is common to use a material harder than the core metal so that the mold does not wear even if it is used repeatedly. By doing so, the core bar is hardly damaged. In addition, in the processes other than the time of forming the elastic layer, it is unavoidable that even if there is a portion in contact with a material harder than the core metal, the effect is exhibited.

  The developing roller has at least one elastic layer. However, in the case of a multi-layer, the same material as the elastic layer 1b can be used. In this case, it is easy to adjust the hardness and resistance of the developing roller. Can be mentioned.

  In addition, when the elastic layer is a multilayer, it is sufficient to obtain at least one elastic layer from a process of injecting a material using a mold and thermosetting, and the other elastic layer may be formed after, for example, tube coating or tube coating. It can be formed by a method of polishing, and is not particularly limited. However, if the formation of the elastic layer using the addition reaction type conductive silicone rubber is a subsequent process, select a material that does not interfere with the reaction / molding of the elastic layer material formed in the previous process. There is a need.

3) Covering layer The covering layer 1c is formed on and in contact with the outer periphery of the elastic layer (the outermost elastic layer in the case of having a plurality of elastic layers), and contains softening oil or plastic contained in the elastic layer. It is provided for the purpose of preventing a component such as an agent from bleeding out to the surface of the developing roller, or for the purpose of adjusting the electric resistance of the entire developing roller.

  The developing roller has at least one coating layer. When the coating layer is a single layer, the thickness of the coating layer is preferably 8 μm or more in order to prevent bleed-out, and the flexibility of the elastic layer is not impaired. Is taken into consideration, it is preferably 100 μm or less, more preferably 30 μm or less. Moreover, when making a coating layer into a multilayer, what is necessary is just to make it the total thickness of each layer be the said range.

  Examples of the resin material include fluorine resin, nylon resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, polyolefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, fluoro-rubber-based thermoplastic elastomer, polyester. Examples thereof include thermoplastic thermoplastic elastomers, polyamide thermoplastic elastomers, polybutadiene thermoplastic elastomers, ethylene vinyl acetate thermoplastic elastomers, polyvinyl chloride thermoplastic elastomers, and chlorinated polyethylene thermoplastic elastomers. These resin materials may be a homopolymer or a copolymer. These resin materials may be used alone or in combination of two or more.

  In the contact development method, the coating layer 1c needs to be pressed uniformly against the photosensitive member of the developing roller, and is also in contact with a regulating blade that regulates the toner layer thickness on the developing roller, so that the coating layer 1c has a trace of deformation. If it remains, it will appear as an image defect. For this reason, the developing roller is preferably a polyurethane resin that requires high compression set against the environmental temperature used in a copying machine, a printer, or the like.

  Polyol compounds used for the urethane resin used in the coating layer 1c include known polyols for polyurethane such as polyethylene glycol, tetramethylene glycol polyethylene diadipate, polyethylene butylene adipate, poly-ε-caprolactone diol, polycarbonate polyol, and polypropylene glycol. Is mentioned.

  As the isocyanate compound, diisocyanates such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and their burette modified products, isocyanurate modified products, urethane modified products and the like are preferably used. be able to. Particularly preferred isocyanate compounds are HDI and its burette-modified products, isocyanurate-modified products, urethane-modified products and the like. The longer the molecular chain of the isocyanate compound, the more the polyurethane coating layer having higher flexibility is generated.

  The covering layer 1c can be added with an appropriate amount of insulating particles to the resin material in order to ensure sufficient toner transportability. As the size of the insulating particles, those having an average particle diameter of 3 μm to 100 μm are desirable, and those having an average particle diameter of 5 μm to 30 μm are more preferable.

  As the material of the insulating particles, for example, urethane particles, nylon particles, acrylic particles, silicone particles and the like can be used. The shape is preferably spherical.

  The amount of the insulating particles added is usually preferably 2 to 50 parts of the insulating particles when the resin material in the coating material forming the coating layer is 100 parts. When the amount of the insulating particles added is within this range, a coating layer surface having an appropriate toner transportability as a developing roller can be obtained.

  The coating material in the present invention contains conductive fine particles for the purpose of adjusting the electric resistance of the entire developing roller. The conductive fine particles include fine particles of a conductive agent (carbon black, graphite, conductive metal oxide, copper, aluminum, nickel, iron powder, etc.) having various electron conduction mechanisms or an ionic conductive agent (alkali metal salt and ammonium salt). Can be used. Two or more of the above conductive agents may be used in combination. Moreover, it is preferable to add 5 to 200 parts of conductive fine particles with respect to 100 parts of the resin material. When the addition amount of the conductive fine particles is 5 parts or more, the coating layer can have good conductivity, and the conductivity can be stably controlled by adding the necessary amount of conductive fine particles up to 200 parts. It becomes possible. More preferably, 15 to 30 parts of conductive fine particles are added to 100 parts of the resin material. The conductive fine particles to be used should not have a material structure that contaminates the photoreceptor.

  The coating layer 1c can be obtained, for example, by dissolving the resin material or the like in an organic solvent to form a coating solution, and applying and drying the solution on the elastic layer. Examples of the organic solvent that can be used to form the coating layer 1c include methyl isobutyl ketone, methyl ethyl ketone, acetone, ketones of cyclohexanone, aromatics such as xylene and toluene, and esters such as n-butyl acetate and ethyl acetate. And ethers such as tetrahydrofuran, ethyl cellosolve, and tetrahydropyran, but are not particularly limited thereto. Moreover, when resin etc. melt | dissolve, water etc. can be used as a solvent.

  Each of the above materials is added to an organic solvent, water, or the like and diluted appropriately, and the conductive agent is dispersed to prepare a coating solution.

  A conventional method can be used to clean the surface of the elastic layer before coating, and the coating liquid of the present invention is applied from the opposite side in the longitudinal direction of the end where the elastic layer material is injected to form a coating layer. By combining with the method, even higher effects can be expected. Specific methods include, for example, spraying compressed air, contact with an adhesive tape, cleaning with an organic solvent that does not attack the elastic layer material, cleaning with high-pressure water, and cleaning with water.

  Examples of the coating method include vertical dip coating, ring coating, roll coating, and the like, and are not particularly limited. When a pulverization step is added in the production of the coating liquid, a ball mill, a sand mill, a vibration mill or the like is used.

  Next, the film produced by the coating method as described above is dried. As a drying method, air drying without heating, heat drying, in the case of a thermosetting resin, heat treatment up to the reaction temperature, etc. It can be selected depending on the material used.

4) Electrophotographic apparatus FIG. 2 is a schematic configuration diagram of an electrophotographic apparatus provided with the developing roller of the present invention. The electrophotographic apparatus shown in FIG. 2 is of a rotating drum type / transfer type. Reference numeral 1 denotes an electrophotographic photosensitive member (photosensitive drum) as a latent image carrier, which is rotationally driven in a clockwise direction at a predetermined peripheral speed (process speed). The photosensitive drum 1 is uniformly charged to a predetermined polarity / potential (-600 V in this embodiment) by a charging roller 2 to which a charging bias is applied from a power source E1 as a charging means during its rotation process, and then exposed. The system 3 receives negative image exposure (analog exposure of the original image, digital scanning exposure) corresponding to the target image information, and an electrostatic latent image of the target image information is formed on the peripheral surface.

  A thin toner layer is formed on the developing roller 4 as the developing roller 4 rotates, and the toner thin layer is supplied onto the photosensitive drum, whereby the electrostatic latent image is developed as a toner image. The developing roller 4 may or may not be in contact with the photosensitive drum. Next, the transfer material P is fed through the paper feed roller 10 to the transfer portion between the photosensitive drum 1 and the transfer roller 5 as the transfer means at a predetermined timing. By applying a transfer bias of 3 kV, the reversely developed toner image on the surface of the photosensitive drum 1 is sequentially transferred to the transfer material P. The transferred toner image is fixed on the recording material P by the fixing roller 11. The recording material P is discharged out of the apparatus by the conveying roller 12.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited at all by these Examples.

(Example 1)
<Manufacture of metal core>
The core metal is formed by applying electroless nickel-phosphorus plating to a steel shaft core of φ8 mm, and adjusting the phosphorus content in the plating film by selecting the type of plating solution, so that the plating film thickness is 3 to 6 μm. It was prepared. In addition, formation of trinickel monophosphide (Ni ₃ P) in the plating film was performed by supplying N ₂ gas into the furnace at 1 dm ³ / min. The sample was removed by heating at 250 ° C. for 3 hours while being introduced at the time when the temperature in the furnace became 80 ° C. or less after 3 hours had elapsed. At this time, the time from the formation of the plating film to the start of heating in the N ₂ gas atmosphere was 10 minutes.

The finished core was subjected to measurement of phosphorus content in the plating film, confirmation of the presence or absence of trinickel monophosphide (Ni ₃ P), and measurement of dynamic ultra-micro hardness.

<Production of elastic layer>
Next, an elastic layer made of conductive silicone rubber is formed by placing the cored bar in a cylindrical mold having an inner diameter of 16 mm so as to be concentric with the mold cavity, and forming a cylinder between the top mold and the top on both sides. The mold with the mold was placed in a molding machine, and liquid rubber was injected using an injection injection device. The injection conditions were an injection time of 10 seconds, and the amount of liquid rubber injected into the mold was 40 ml, which was injected at a constant rate of 4 ml / second. Here, liquid conductive silicone rubber (manufactured by Toray Dow Corning Co., Ltd., volume specific resistance 1 × 10 ⁶ Ωcm product) is used as the liquid rubber, platinum catalyst mixed in a small amount in one liquid, and further cured in the other liquid A two-component addition reaction type compounding agent was used.

  The mold into which the liquid rubber has been injected is heated and cured at 115 ° C. with a hot plate in the molding apparatus. After demolding, secondary vulcanization is carried out in an oven at 200 ° C. for 4 hours. A developing roller precursor having an elastic layer was obtained.

<Preparation of coating layer>
Next, the coating layer is formed by diluting a urethane paint (Nipporan N5033; trade name, manufactured by Nippon Polyurethane Co., Ltd.) with methyl ethyl ketone so that the solid content concentration becomes 10%, and carbon black (MA100; trade name, Mitsubishi, as a conductive agent). Chemical) is 70 parts with respect to 100 parts of the solid content of the urethane paint, and urethane particles (Art Pearl C400; trade name, manufactured by Negami Kogyo Co., Ltd.) having an average particle size of 14 μm as insulating particles are added to 100 parts of the solid content of the urethane paint. After 10 parts are added, 10 parts of a curing agent (Coronate L; trade name, manufactured by Nippon Polyurethane Co., Ltd.) is added to 100 parts of the solid content of the urethane paint, and the mixture is stirred. Prepared. Next, this coating liquid is put into a circulator of a vertical dip coating apparatus, adjusted to a liquid temperature of 23 ± 1 ° C. and a liquid viscosity of 14.0 mPa · s, and coated with the developing roller precursor obtained by the above method. Gripping onto a work pallet, applying a vertical dip coating solution, air drying at room temperature for 30 minutes, drying in an oven at 80 ° C. for 15 minutes, and further curing in an oven at 140 ° C. for 4 hours to form a coating layer, A developing roller was obtained.

<Evaluation method>
Next, the exposed portions of the cored bar at both ends of the developing roller obtained as described above were observed visually, and the number of occurrences of 100 developing rollers produced by the same method was checked for the presence or absence of scratches on the surface of the cored bar. The results are shown in Table 1.

<Measurement of phosphorus content in plating film>
The phosphorus content was quantitatively analyzed by energy dispersive X-ray analysis (Hitachi, Ltd. S-4300, Edax Japan, Ltd., Phoenix System). The measurement was performed by the non-standard method after calibration was performed, and three points were measured for each sample piece and the average value was adopted.

<Confirmation of trinickel phosphide (Ni ₃ P) in the plating film>
The confirmation of the formation of trinickel monophosphide (Ni ₃ P) was measured by the parallel beam method of X-ray diffraction, and the X-ray incident angle was 0.1 °.

<Measurement of dynamic ultra-micro hardness>
The measurement of dynamic ultra micro hardness was performed by a dynamic ultra micro hardness meter DUH-W201S (manufactured by Shimadzu Corporation). The dynamic ultra-micro hardness is calculated by the following formula from the test load P (mN) and the indentation depth D (μm) when the indenter is allowed to enter the sample at a constant indentation speed (mN / s). α is a constant depending on the shape of the indenter.
Dynamic microhardness = α × P / D2
The test conditions were determined by allowing a 115 ° triangular pyramid indenter (α = 3.8854) to penetrate the core metal surface at an indentation speed of 0.28 mN / s and a test load of 15 mN. The test load was set so that the indentation depth was 1/10 or less of the plating film thickness.

(Example 2)
A developing roller was produced in the same manner as in Example 1 except that the formation temperature of trinickel phosphide (Ni ₃ P) in the plating film was changed to 500 ° C. in Example 1.

(Example 3)
A developing roller was produced in the same manner as in Example 1 except that the formation temperature of trinickel phosphide (Ni ₃ P) in the plating film was changed to 200 ° C. in Example 1.

(Example 4)
A developing roller was produced in the same manner as in Example 1 except that the type of plating solution used in forming the electroless nickel-phosphorous plating was changed.

(Example 5)
In Example 1, a developing roller was produced in the same manner as in Example 1 except that the time from the formation of the plating film to the start of heating in the N ₂ gas atmosphere was 24 hours.

(Comparative Example 1)
In Example 1, except that the formation of trinickel phosphide (Ni ₃ P) in the plating film after the electroless nickel-phosphorus plating was not performed (other than the heating after the plating film was formed), Otherwise, a developing roller was prepared in the same manner as in Example 1.

(Comparative Example 2)
In Example 4, except that the formation of trinickel monophosphide (Ni ₃ P) in the plating film after the electroless nickel-phosphorous plating was not performed (other than heating was not performed after the plating film was formed), Otherwise, a developing roller was produced in the same manner as in Example 4.

As apparent from Table 1, in Examples 1 to 5, after the plating film was formed, the cored bar was heat-treated in a nitrogen atmosphere, whereby trinickel monophosphide (Ni ₃ P) was formed in the plating film. For this reason, as a result, the hardness of the surface of the core metal is increased, and it is difficult to damage the core metal.

On the other hand, in Comparative Example 1 and Comparative Example 2, there is no step of forming trinickel monophosphide (Ni ₃ P) in the plating film, and thus generation of trinickel monophosphide (Ni ₃ P) is also observed. In addition, there was no increase in hardness, and the core metal was damaged when the developing roller was produced.

It is a schematic sectional drawing which shows one Embodiment of the developing roller of this invention. 1 is a schematic view of an electrophotographic apparatus including a developing roller of the present invention.

Explanation of symbols

1a Core 1b Elastic layer 1c Covering layer 1 Electrophotographic photosensitive member (photosensitive drum)
2 Charging means 3 Exposure system 4 Developing means 5 Transfer roller 6 Cleaning means 9 Cleaning roller 10 Feeding roller 12 Conveying rollers E1, E2, E3 Power supply for bias application

Claims (5)

In the developing roller in which an elastic layer formed of conductive silicone rubber and a coating layer are formed in order from the inner peripheral side on the outer periphery of the core metal,
A developing roller characterized in that the surface of the metal core is coated with a plating containing at least phosphorus and nickel, and the plating film contains trinickel monophosphide (Ni ₃ P). 2. The developing roller according to claim 1, wherein a content of trinickel monophosphide (Ni ₃ P) in the coating film is 3% by mass to 70% by mass. Forming a plating film containing at least phosphorus and nickel on the surface of the metal core by electroless nickel-phosphorus plating;
Forming a nickel triphosphide (Ni ₃ P) in the plating film by heat-treating the plating film at 200 ° C. to 500 ° C .;
The core metal on which the trinickel monophosphide (Ni ₃ P) is formed is arranged in a metal cylindrical mold so as to be concentric with the cylindrical mold, and in the gap between the core metal and the cylindrical mold Injecting a conductive silicone rubber material and thermosetting it to form an elastic layer made of conductive silicone rubber on the core;
Forming a coating layer on the outer periphery of the elastic layer;
A method for producing a developing roller, comprising: 4. The development according to claim 3, wherein after the plating film is formed, the time until the step of forming trinickel monophosphide (Ni ₃ P) in the plating film by the heat treatment is within 24 hours. Roller manufacturing method.   The method for manufacturing a developing roller according to claim 3, wherein the heat treatment is performed in an inert atmosphere or a reducing atmosphere.

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