JP2010085838A - Forming mold for elastic roll, elastic roll, process cartridge and image forming apparats - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming mold for elastic roll that has sufficient durability even in repeated formation of an elastic layer for an elastic roll from a material. <P>SOLUTION: The forming mold 11 for elastic roll is used for manufacturing the elastic roll that has a shaft core body 12 and the elastic layer on the outer periphery of the shaft core body. The surface of the mold has at least a metal nitride layer, and has an electroless plating layer on the metal nitrite layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mold for forming an elastic roll used in producing a developing roll. The present invention also relates to an elastic roll formed using this mold, a process cartridge and an image forming apparatus in which the elastic roll is mounted as a developing roll.

  The formation of the elastic layer of an elastic roll in which various materials with various functions such as elasticity and conductivity are arranged on the outer periphery of a rigid shaft core such as metal is compared without the need for post-processing such as polishing. Since an elastic roll having a desired shape accuracy can be obtained with good reproducibility, it is performed by molding.

  In this mold molding, the shaft core is placed in a cylindrical mold by supporting both ends thereof with a piece with an injection port, and a liquid elastic layer material is injected from the injection port. By heating, the elastic layer material is thermoset to obtain an elastic roll having a desired shape.

  In recent years, the shape accuracy required for elastic rolls is very strict, and durability performance when used continuously for a long period of time is an important required characteristic as well as the initial shape accuracy required for a mold. In other words, the mold is required to have mechanical strength and impact resistance so that it will not be worn, deformed, chipped, etc. even by repeated mold sets and mold variations. From such a background, materials that have been subjected to various heat treatments to improve mechanical strength are used as materials used in the mold.

  However, materials with improved mechanical strength as described above often have the disadvantage of being inferior in workability, and in the case of dies that require high-definition processing such as mirror finish, processing time Problems such as extension occur. In addition, when the material before heat treatment with sufficient potential is heat treated after processing to improve the mechanical strength, the heat treatment is performed after precision processing. Deformation may occur from the processing dimensions.

  In response to the above problems, a method has been proposed in which a material having a hardness that can be processed even before or after heat treatment is used, and after the processing, only the surface is subjected to modification treatment (nitriding treatment, carbonization treatment, etc.). ing.

  For example, nitriding has been proposed as a method capable of imparting sufficient strength to be used for forming an elastic layer at a relatively low temperature (Patent Document 1).

When an elastic roll is used as a developing roller in an image forming apparatus, the functions required of products have been increasing and sophisticated in recent years, and accordingly, many properties have been required for the elastic layer of the elastic roll. Yes. In order to meet all the requirements, the range of choices for the material of the elastic layer has become narrower than before, and silicone rubber is now widely used. Of these, from the viewpoint of being suitable for injection molding using a metal mold, addition-reaction crosslinked silicone rubber is often used. When the addition reaction cross-linked silicone rubber is molded with the mold having the nitriding surface, the durability of the mold is improved by the nitride layer present on the mold surface, but further improvement of the durability is desired. (Patent Document 2).
Japanese Patent Laid-Open No. 11-172411 JP 2007-212516 A

  An object of the present invention is to provide a mold for forming an elastic roll exhibiting sufficient durability even when the material of the elastic layer of the elastic roll is repeatedly formed.

  The elastic roll molding die of the present invention is an elastic roll molding die used for producing an elastic roll having an axial core body and an elastic layer on the outer periphery of the axial core body. It has a nitride layer, and has an electroless plating layer on the metal nitride layer.

  The mold for forming an elastic roll of the present invention exhibits sufficient durability even when the material of the elastic layer of the elastic roll is repeatedly formed. Further, when an elastic roll manufactured using the mold is used as a developing roll in a process cartridge and an image forming apparatus, the developing roll has a high shape accuracy, so that a good image without density unevenness over the entire printing surface can be obtained. Obtainable.

[Elastic roll mold]
An elastic roll molding die according to the present invention is an elastic roll molding die used for manufacturing an elastic roll having an axial core body and an elastic layer on the outer periphery of the axial core body. It has at least a metal nitride layer, and has an electroless plating layer on the metal nitride layer.

  An example of an elastic roll molding die according to the present invention is shown in FIG.

  The elastic roll molding die 11 includes a cylindrical die 13 and pieces 14a and 14b.

  The shaft core body 12 is held by shaft core body holding portions 15 a and 15 b provided at the center of the pieces 14 a and 14 b, and is placed on the cylindrical mold 13. The piece 14a has an injection port 16 for injecting the elastic layer material. The piece 14b has the discharge port 17 for discharging | emitting the gas in the cavity 18 in a metal mold | die, and an excess elastic layer raw material. The injection port 16 and the discharge port 17 communicate with the outside through flow paths 19a and 19b, respectively.

[Metal nitride layer]
In the present invention, at least the inner surface of the cylindrical mold 3 has a metal nitride layer, and further has an electroless plating layer on the metal nitride layer.

  The metal nitride layer may be deposited on the inner surface of the mold by a known method such as chemical vapor deposition (CVD), physical vapor deposition (PVD), or sputtering. A method of nitriding the metal base surface of the mold is preferable. Steel is generally used as the base metal material for the elastic roll mold from the viewpoint of mechanical strength. By nitriding the inner surface of the steel mold, iron nitriding can be performed easily. A physical layer can be formed. From such a viewpoint, the metal nitride layer is preferably iron nitride.

  Examples of the nitriding treatment include a gas nitriding method, a salt bath nitriding method, a gas soft nitriding method, a plasma nitriding method, and the like. The reason is that the dimensional change of the object to be processed is small and the processing time is relatively short. Therefore, the gas soft nitriding method is preferable. In the gas soft nitriding method, ammonia gas is blown into an electric furnace containing an object to be processed, and the temperature in the furnace is set to 500 to 600 degrees, whereby a part of the ammonia gas is decomposed to generate nitrogen. An iron nitride layer can be formed by combining with metal elements in the vicinity of the steel middle surface. The in-furnace treatment temperature and the in-furnace treatment time can be appropriately selected, but the in-furnace treatment temperature is preferably 480 to 520 ° C., and the in-furnace treatment time is preferably 3 to 6 hours. By the nitriding treatment, nitrogen diffuses and penetrates from the mold surface (the entire inner surface and outer peripheral surface) to a depth of about 500 μm and is covered with an iron nitride layer having the same thickness. The thickness of the metal nitride layer is preferably 1 μm or more and 150 μm or less from the viewpoint of ensuring appropriate durability and productivity.

[Electroless plating layer]
The elastic roll molding die according to the present invention has an electroless plating layer on the metal nitride layer.

  In the mold having the metal nitride layer formed on the inner surface, the durability of the mold is improved when the addition reaction cross-linked silicone rubber is molded by laminating the electroless plating layer on the metal nitride layer. To do.

  That is, the mechanical strength and durability of the mold are improved by the presence of the metal nitride layer. However, since the nitrogen atoms in the metal nitride layer are active (act as a ligand) with respect to the platinum catalyst in the silicone rubber material, the nitrogen atoms are slightly changed by repeated material injection and curing. It is taken into the rubber material and promotes denitrification of metal nitride. Therefore, by laminating an electroless plating layer on the metal nitride layer, the denitrification of the metal nitride is suppressed, and the effect of the metal nitride layer for improving the mechanical strength of the mold is maintained for a long time. be able to. Further, by forming the plating layer by electroless plating, a plating layer having a uniform film thickness and good wear resistance can be formed.

  Examples of the metal of the electroless plating layer include nickel, gold, cobalt, copper and the like, and nickel is preferable.

  The thickness of the electroless plating layer is preferably 3 μm or more and 8 μm or less from the viewpoint of preventing corrosion. More preferably, it is 5 μm. The surface roughness of the electroless plating layer is preferably 0.2 μm or more and 3 μm or less, although it depends on the surface roughness of the underlying metal.

As a method for forming an electroless nickel plating layer on the surface of a mold, for example, nickel sulfate (NiSO ₄ ) is used as a plating bath, and sodium hypophosphite (NaH ₂ PO ₂ ) is used as a reducing agent. This can be done by setting the time from several minutes to several tens of minutes.

(Shaft core)
As a material constituting the shaft core used in the present invention, an alloy such as iron, aluminum, titanium, copper and nickel, an alloy such as stainless steel, duralumin, brass and bronze containing these metals, and carbon black and carbon fiber are used. A known material exhibiting rigidity and conductivity, such as a composite material hardened with plastic, can be used. Further, the surface of the shaft core body may be plated with nickel, copper, zinc or the like.

  The shaft core used in the present invention is, for example, a cylinder having a carbon steel alloy surface subjected to industrial nickel plating having a thickness of 5 μm. Moreover, as a shape, it can also be set as the cylindrical shape which made the center part the cavity other than column shape.

[Elastic layer material]
As the material of the elastic layer, a material appropriately blended with the following silicone rubber, conductive agent, catalyst and the like can be used.

<Silicone rubber>
As a silicone rubber that can be used as a material for the elastic layer, it is excellent in processability, has no by-product accompanying the curing reaction, has good dimensional stability, and has stable physical properties after curing. It is preferable to use an addition reaction cross-linked silicone rubber.

  The addition reaction crosslinking silicone rubber contains, for example, an organopolysiloxane represented by the following formula (1) and an organohydrogenpolysiloxane represented by the following formula (2) as raw materials.

  (In the formula, at least one of R1 and R2 represents an alkenyl group, and x is a positive integer)

(In the formula, y is an integer of 2 or more, and z is a positive integer)
The organopolysiloxane represented by the formula (1) is a base polymer of a silicone rubber raw material, and the molecular weight is not particularly limited, but is preferably 100,000 or more and 1,000,000 or less, and the average molecular weight is 400,000 or more and 700,000. The following is preferred. Furthermore, the viscosity of the organopolysiloxane is preferably 10 Pa · s or more and 250 Pa · s or less from the viewpoint of processing characteristics and physical properties of the elastic layer material at the time of blending.

  The alkenyl group of the organopolysiloxane represented by the formula (1) is a site that forms a crosslinking point by reacting with the active hydrogen of the organohydrogenpolysiloxane represented by the formula (2). Not. However, for reasons such as high reactivity with active hydrogen, at least one of a vinyl group and an allyl group is preferable, and a vinyl group is more preferable.

  The organohydrogenpolysiloxane represented by the formula (2) functions as an addition reaction crosslinking agent in the curing step as described above, and the number of silicon-bonded hydrogen atoms in one molecule is 2 or more. is there. In order to appropriately perform the curing reaction, a relatively low molecular weight, specifically 1000 or more and 5000 or less is preferable. Moreover, it is preferable from a viewpoint of bridge | crosslinking that the repeating unit enclosed by y and z in the said Formula (2) is couple | bonded at random.

<Conductive agent>
In addition to the silicone rubber, a conductive agent can be blended in the elastic layer material as necessary. For example, metal powders and fibers such as aluminum, palladium, iron, copper and silver; metal oxides such as titanium oxide, tin oxide and zinc oxide; metal compound powders such as copper sulfide and zinc sulfide; or suitable particles Surface of tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, aluminum, gold, silver, copper, chromium, cobalt, iron, lead, platinum or rhodium electrolytic treatment, spray coating or mixing / shaking, etc. And carbon powders such as acetylene black, ketjen black, PAN-based carbon black, pitch-based carbon black, and the like. Further, ion conductive materials such as KSCN, LiClO ₄ , NaClO ₄ , and quaternary ammonium salts can be used.

  As the conductive agent, carbon black is particularly preferable because the electrical resistivity can be reduced by adding a relatively small amount, and conductivity can be imparted without increasing the hardness of the elastic layer material.

<Catalyst>
In addition to the silicone rubber, the elastic layer material can be blended with a catalyst for accelerating crosslinking as required. As the catalyst, platinum, palladium or the like can be used. The present invention is particularly effective when such a catalyst is used.

  In addition to the conductive agent and the catalyst, a filler or the like can be added to the elastic layer material as necessary.

(Production of elastic roll)
The elastic layer is molded by housing the shaft core body in the elastic roll molding die, injecting the elastic layer raw material into the cavity, and heating and curing. The mold into which the elastic layer raw material has been injected is placed in a heating furnace and arranged in a heating furnace having a shelf, or the elastic layer is moved by moving through the heating furnace by being locked to a conveying means such as a chain. Heat cured. After the curing is finished, the elastic roll is taken out by cooling. Thereafter, if necessary, the elastic roll is subjected to secondary curing treatment by reheating. On the other hand, the mold is used for the next elastic roll production.

  The joint portion of the elastic roll formed with the elastic layer and the protruding portion of the piece into the flow path of the piece are removed by trimming as necessary.

  The thickness of the elastic layer is preferably 1 mm or more and 6 mm or less, and more preferably 1.5 mm or more and 5.5 mm or less. If the thickness is less than 1 mm, it may be difficult to ensure a uniform nip to the photoreceptor when used as a developing roll. On the other hand, even if the thickness is greater than 6 mm, not only does the charging performance of the toner not improve, but the molding cost of the elastic layer increases, which is disadvantageous in terms of cost.

Moreover, when using an elastic roll as a developing roll, electroconductivity can be adjusted by mix | blending a required amount of the said electrically conductive agent. The conductivity of the elastic layer is preferably 10 ² Ω or more and 10 ¹⁰ Ω or less, more preferably 10 ⁴ Ω or more and 10 ⁸ Ω or less. When carbon black is used as the conductive agent, the amount of carbon black is preferably 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the silicone rubber.

  Further, the hardness of the elastic layer was measured with a rubber hardness meter “Micro Rubber Hardness Meter MD-1” (trade name, manufactured by Kobunshi Keiki Co., Ltd.) in an environment with an air temperature of 25 ° C. and a relative humidity of 50% RH. The micro rubber hardness is preferably 20 ° or more and 60 ° or less.

(Formation of surface layer)
A surface layer can be further formed on the outer periphery of the elastic layer of the elastic roll produced as described above. Hereinafter, the elastic roll formed with the surface layer is referred to as a multilayer elastic roll.

  As shown in FIG. 2, the multilayer elastic roll has an elastic layer 21 on the outer periphery of the shaft core 12, and further has a surface layer 22 on the outer periphery of the elastic layer 21.

  The surface layer is a layer provided for controlling the surface characteristics of the elastic roll, and further for preventing the low molecular weight component of the elastic layer from oozing out. Also good.

  As the material for the surface layer, for example, various polyamides, fluorine resins, hydrogenated styrene-butylene resins, urethane resins, silicone resins, polyester resins, phenol resins, imide resins, olefin resins, and the like can be used.

  These materials can be dispersed in an appropriate solvent such as methyl ethyl ketone, toluene, or methyl isobutyl ketone by using a conventionally known dispersing apparatus using beads such as a sand mill, a paint shaker, a dyno mill, and a pearl mill. By performing this dispersion, a coating solution for obtaining a surface layer with few surface defects can be obtained.

  The obtained dispersion for forming the surface layer can be coated on the elastic layer by spray coating, dipping, or the like.

  When the multilayer elastic roll is used as a member for an electrophotographic process, the thickness of the surface layer is preferably 5 μm or more because contamination of the image forming body due to exudation of the elastic layer component can be further prevented. Further, it is preferably 500 μm or less from the viewpoint of preventing the surface of the multilayer elastic roll from becoming hard and preventing toner fusion. More preferably, it is 10 μm or more and 30 μm or less.

  When using a multilayer elastic roll as a developer-carrying roll, the developer on the surface of the developer-carrying roll can be easily conveyed by dispersing fine particles having a mass average particle diameter of 1 to 20 μm in the surface layer. It is preferable because a sufficient amount of developer can be conveyed to the development area. Examples of the fine particles include plastic pigments such as polymethyl methyl methacrylate fine particles, silicone rubber fine particles, polyurethane fine particles, polystyrene fine particles, amino resin fine particles, and phenol resin fine particles. In particular, polymethyl methyl methacrylate fine particles and polyurethane fine particles are preferred. These fine particles are preferably added in a range of 3% by mass to 200% by mass with respect to the total mass of the surface layer constituent components excluding the fine particles.

[Process cartridge, image forming apparatus]
FIG. 3 shows a schematic view of an example of an image forming apparatus of a contact developing system in which the elastic roll or the multilayer elastic roll is incorporated as a developing roll.

  The process cartridge according to the present invention is a process cartridge that integrally supports the photoreceptor 31, the charging roll 32, the developing roll 33, and the cleaning member 38, and is detachable from the image forming apparatus. The developing roll 33 is the elastic roll or the multilayer elastic roll.

  The image forming apparatus according to the present invention is an image forming apparatus having a photoreceptor 31, a charging roll 32, a developing roll 33, a transfer roll 42, a cleaning member 38, a fixing roll 44, and a pressure roll 45, and the process cartridge is incorporated therein. It has been.

  Further, even if the process cartridge is not incorporated, it is sufficient if it has the elastic roll or multilayer elastic roll of the present invention as the developing roll 33.

  In the image forming apparatus shown in FIG. 3, the photoreceptor 31 uniformly charged by the charging roll 32 rotates in the direction of the arrow, and recording information is placed on the surface between the charging roll 32 and the developing roll 33. Laser light 40 is irradiated to form an electrostatic latent image. On the other hand, the developer 37 sent to the developer supply roll 34 by the stirring blade 36 is uniformly coated on the surface of the developing roll 33 by the developer layer thickness regulating member 35 and is carried to the surface of the photoreceptor 31, and the surface of the photoreceptor 31. The electrostatic latent image formed thereon is visualized as a toner image. When the photoconductor 31 further rotates and the toner image reaches the transfer area, the toner image is transferred onto a recording medium 43 such as paper by a transfer roll 42 that is opposed to the photoconductor 31. The surface of the photoreceptor 31 is uniformly charged again by the charging roll 32 after the developer remaining on the surface without being transferred to the recording medium 43 is removed by the cleaning member 38.

  The unfixed toner image transferred to the recording medium 43 passes between the fixing roll 44 and the pressure roll 45, is fixed to the recording medium 43 by pressure and heat, and is discharged from the image forming apparatus.

  On the other hand, the developer remaining on the surface of the developing roll 33 without being used for development returns to the developing container 41 while being carried on the surface of the developing roll. Inside the developing container 41, the developer supply roll 34 returns the developer returned from the surface of the developing roll 33 and supplies a new developer to the surface of the developing roll 33. The new developer supplied to the surface of the developing roll 33 is uniformly adjusted by the developer layer thickness regulating member 35 and is transported to the developing area. By repeating this, the developing roller 33 always carries a new developer with a uniform thickness to develop the electrostatic latent image.

  The present invention is described in detail by the following examples, but these are not intended to limit the present invention. Unless otherwise specified, commercially available high-purity products were used.

[Elastic roll shape accuracy measurement]
As shown in FIG. 4, the shape accuracy of the elastic roll is obtained by inserting the elastic roll 53 and the roll external reference plate between the laser beams of a laser length measuring device (trade name: “LS-5040”, manufactured by Keyence). 53 was rotated at a rotational speed of 120 ° / s, and the distance between the outer diameter end surface of the elastic roll 53 and the external reference plate was measured every 0.33 s (every rotation angle 3.6 °). Among the data (100 pieces) of the interval corresponding to one round of the obtained elastic roll 53, the difference between the maximum value and the minimum value was defined as “flare” at the measurement point. The measurement was performed at an interval of 5 mm from one end of the elastic layer of the elastic roll 53 and the other end. Among the flare of each measurement point, the maximum value was the flare of the elastic roll.

[Durability evaluation of molds]
The durability performance of the mold was evaluated by measuring the shape accuracy of the elastic roll every time the number of molding shots of the mold elapsed, and confirming the change in the shape accuracy of the mold over time.

The measurement of the shape accuracy was performed on 30 samples before and after the initial 1st shot / 1000th shot / 10000th shot / 20000th shot (initially 1 to 30 shots).
Evaluation was performed according to the following criteria.
○: The increase rate of the average value of the flare at the 20000th shot is less than 5% compared to the initial value (can be used as it is)
Δ: Increase rate of the average value of the 20000 shot flare compared to the initial value is within 20% (can be used as it is)
Correction required: The increase rate of the average value of the flare at the 20000th shot exceeds 20% compared to the initial value (need to be corrected by removing from the line).

[Image evaluation]
A multilayer elastic roll described later was used as a developer carrying roll, and image evaluation was performed. The electrophotographic laser beam printer (trade name: “LBP2510”, manufactured by Canon Inc.) used in this evaluation is an A4 version output machine, the output speed of the recording medium is A4 vertical 16 sheets / minute, and the image resolution is 600 dpi. The photoreceptor is a reversal development type photosensitive drum in which an OPC (organic photoconductor) layer is coated on an aluminum cylinder, and the outermost layer has a charge transport layer using a modified polycarbonate as a binder resin.

  The toner image developed on the photoreceptor is transferred to a recording medium by a transfer roll and thermally fixed by a fixing unit. The toner that has not been transferred by the transfer roll is scraped off from the photoreceptor by a cleaning blade. The developing portion is formed into a cartridge, and a developing blade, which is a toner layer thickness regulating member, contacts the developer carrying roll in the counter direction to regulate the toner layer thickness.

Image evaluation was performed according to the following criteria using a solid image and a halftone image.
◯: The image density is sufficiently high and there is no density unevenness over the entire printing surface. Δ: Although minute density unevenness occurs, there is no practical problem. ×: Density unevenness occurs over the entire printing surface.

  In addition, it is known that this image evaluation is ◯ when the elastic roll shape accuracy is 30 μm or less, Δ when it is larger than 30 μm and 35 μm or less, and x when it exceeds 35 μm.

[Example 1]
[Preparation of elastic layer molds]
In this example, a cylindrical steel elastic layer forming mold having an inner diameter of φ16 mm and an outer diameter of φ26 mm shown in FIG. 1 was produced. First, after processing the pipe inner diameter of a steel mold into a desired shape, an iron nitride layer was formed on the surface by performing gas soft nitriding on the inner surface. The gas soft nitriding treatment condition is that after the processed mold is placed in a heating furnace, the temperature in the heating furnace is raised to 500 ° C., and nitrogen gas containing 30% ammonia gas is fed to form a processed mold. After treatment for 4 hours, an iron nitride layer was formed in the vicinity of the mold surface. Thereafter, electroless nickel plating with a film thickness of 5 μm and a nickel / phosphorus ratio of 92: 8 by mass ratio was applied to the surface of the nitridized mold to obtain a mold for forming an elastic layer. Electroless nickel plating was performed on the mold surface by a hypophosphorous acid precipitation method.

(Elastic layer molding)
A release agent made of a fluororesin was applied to the inner surface of the elastic layer forming mold by spraying. Thereafter, as shown in FIG. 1, the shaft core 11 obtained by applying chemical nickel plating with a thickness of 5 μm to an iron round bar having a diameter of 8 mm and a length of 280 mm is placed on the pieces 22 and 23 disposed at both ends of the mold 21. It was installed in the mold 21 so as to be supported.

  From the inlet 27 of the piece 23, addition reaction cross-linked liquid silicone rubber (raw material of the elastic layer (organopolysiloxane, organohydropolysiloxane, conductive carbon black, platinum catalyst, quartz, silica appropriately blended, liquid The viscosity in the state: 150 Pa · s, the Asuka C hardness after curing: 40 °), until the liquid silicone rubber overflows from the discharge port 26 by bringing the material injection nozzle of the molding machine into contact with the injection port 27. Inject for 10 seconds at a constant flow rate. Thereafter, the mold 21 was heated at 100 ° C. for 30 minutes to cure the liquid silicone rubber in the mold. After curing, the mold 21 was cooled to 80 ° C. and then removed to obtain an elastic roll having an elastic layer having an axial length of 230 mm and a thickness of 4 mm. Needless to say, it is possible to remove the mold immediately after being cured from the heated mold, but by appropriately cooling it, the mold can be easily removed and handled in the next step. Furthermore, secondary curing was performed by heating in an oven at 200 ° C. for 4 hours. The shape accuracy of each of the elastic rolls subjected to the secondary curing of the 1000th shot / 10000th shot / 20,000th shot was measured. The results are shown in Table 1.

(Surface layer formation)
On the outer circumference of the elastic layer of the elastic roll, a coating liquid in which urethane particles having an average particle diameter of 15 μm and conductive carbon black were blended with a polyurethane resin raw material was applied by a dipping method. Then, the multilayer elastic roll which has the surface layer which consists of urethane resin on the outer periphery of an elastic layer was obtained by hardening in 150 degreeC oven for 4 hours. A multilayer elastic roll was prepared for the elastic roll having the number of mold shots of 20000, and the image evaluation was carried out using the multilayer elastic roll as a developer carrying roll. The results are shown in Table 1.

[Comparative Example 1]
An elastic roll and a multilayer elastic roll were produced and evaluated in the same manner as in Example 1 except that the inner surface of the elastic layer forming mold was not subjected to electroless nickel plating. The results are shown in Table 1.

[Comparative Example 2]
An elastic roll and a multilayer elastic roll were produced and evaluated in the same manner as in Example 1 except that the gas soft nitriding treatment was not performed on the inner surface of the elastic layer forming mold. In this comparative example, since the flare greatly increased at the 10,000th shot, a multilayer elastic roll was prepared for the elastic roll at the 10,000th shot, and image evaluation was performed using the multilayer elastic roll as a developer carrying roll. The results are shown in Table 1.

  In Example 1, since the nitriding treatment is performed on the inner surface of the elastic layer molding die, the mechanical strength is improved. Furthermore, since the electroless nickel plating is applied on the iron nitride layer, it can withstand repeated molding of the addition reaction crosslinked silicone rubber. Therefore, even after using 20000 shots, the mechanical strength of the mold was maintained, and the elastic roll satisfying the shape accuracy and the image performance could be formed with little wear.

  In contrast, in Comparative Example 1, the inner surface of the elastic layer molding die was subjected to nitriding treatment, and the mechanical strength was improved, so that it was able to withstand use up to the 10,000th shot. However, since the electroless nickel plating layer is not applied on the surface of the iron nitride layer, the mechanical strength of the liquid silicone rubber is further reduced by repeated molding of the liquid silicone rubber. increased. For this reason, it was necessary to remove the mold from the line and correct the mold for subsequent use.

  Furthermore, in Comparative Example 2, since electroless nickel plating was directly applied to the inner surface of the elastic layer molding die, 50% flex increased compared to the initial time at the 10,000th shot, and in this case also, the die was corrected. There was a need.

  The elastic roll of the present invention can be suitably used as an electrophotographic process cartridge or a developing roll for an electrophotographic image forming apparatus, for example.

1 is a conceptual cross-sectional view of an elastic layer molding die according to the present invention. It is sectional drawing and a perspective view of an example of the elastic roller which concerns on this invention. 1 is a schematic view of an example of an image forming apparatus according to the present invention. It is a conceptual diagram of the shape accuracy measuring apparatus of the elastic roll in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Elastic roll shaping | molding die 12 Shaft core body 13 Cylindrical metal mold | die 14a, 14b Piece | frame 15a, 15b Shaft core body holding | maintenance part 16 Inlet 17 Outlet 18 Cavity 19a, 19b Channel 21 Elastic layer 22 Covering layer 31 Photoconductor 32 Charging roll 33 Developing roll 34 Developer supply roll 35 Developer layer thickness regulating member 36 Stirring blade 37 Developer (toner)
38 Cleaning member 40 Laser beam 41 Developer container 42 Transfer roll 43 Recording medium (paper)
44 fixing roll 45 pressure roll 51 laser light emitting part 52 laser light receiving part 53 elastic roll 54 outer diameter

Claims (11)

In an elastic roll molding die used for manufacturing an axial roll and an elastic roll having an elastic layer on the outer circumference of the axial roll,
A mold for elastic roll molding comprising at least a metal nitride layer on a surface of the mold and an electroless plating layer on the metal nitride layer.   2. The mold for elastic roll molding according to claim 1, wherein the metal nitride layer is a layer formed by nitriding a metal base surface of a mold.   The elastic roll molding die according to claim 1 or 2, wherein the metal nitride layer is an iron nitride layer.   The mold for elastic roll molding according to any one of claims 1 to 3, wherein the electroless plating layer is an electroless nickel plating layer.   5. The elastic roll molding die according to claim 1, wherein a thickness of the electroless plating layer is 3 μm or more and 8 μm or less. A shaft core, and an elastic roll having at least an elastic layer on the outer periphery of the shaft core,
An elastic roll, wherein the elastic layer is manufactured using the elastic roll molding die according to any one of claims 1 to 5.   The elastic roll according to claim 6, wherein the elastic layer contains an addition reaction cross-linked silicone rubber.   The elastic roll according to claim 6, wherein the elastic roll has at least one surface layer on an outer periphery of the elastic layer. In a process cartridge that integrally supports a photoreceptor, a charging roll, a developing roll, and a cleaning member and is detachable from an image forming apparatus,
A process cartridge, wherein the developing roll is the elastic roll according to any one of claims 6 to 8. In an image forming apparatus having a photoreceptor, a charging roll, a developing roll, a transfer roll, a cleaning member, a fixing roll and a pressure roll,
An image forming apparatus in which the process cartridge according to claim 9 is incorporated. In an image forming apparatus having a photoreceptor, a charging roll, a developing roll, a transfer roll, a cleaning member, a fixing roll and a pressure roll,
The image forming apparatus, wherein the developing roll is the elastic roll according to claim 6.

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