JP4205527B2 - Rubber roller and manufacturing method thereof - Google Patents

Description

  The present invention relates to a rubber roller, and in particular, it is used for a charging rubber roller, a developing rubber roller, a transfer rubber roller, a fixing rubber roller, a paper feeding rubber roller, etc. used in an electrophotographic copying machine or the like. The present invention relates to a rubber roller and a manufacturing method thereof.

  Many rubber rollers such as a charging roller, a developing roller, and a transfer roller are used in an electrophotographic apparatus such as a laser printer and a facsimile. These rubber rollers are generally composed of, for example, a shaft body and one or more vulcanized rubber layers formed on the outer periphery thereof. Furthermore, since the rubber roller is fixed to a bearing portion of the apparatus main body or the cartridge main body and rotated, for example, the rubber roller is usually used by providing portions with exposed shaft bodies at both ends.

As the shaft used for the above-mentioned purposes, a plated body is usually used. 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, 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 that uses 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.
JP-A-11-70594 Japanese Patent Publication No. 7-74056 Toshio Okamura, Shigemitsu Kawagishi, Tokuzo Kobe, Osamu Takano; “Application of Electroless Plating”, p170-173, (1991), Tsuji Shoten

  However, when vulcanizing after coating an unvulcanized rubber composition containing at least one of sulfur or a vulcanizing agent containing a sulfur atom in the molecular structure on the outer periphery of a shaft body subjected to electroless nickel plating As a result, discoloration of the plating film and fixation of the vulcanized rubber occur, making it impossible to remove the rubber when the plated surface of the shaft body is exposed at the portion where the rubber layer is not formed. Therefore, it is necessary to clean and remove in a later process, leading to cost increase and quality variation. Even if discoloration or rubber sticking does not occur, the plating film peels off when the rubber layer is removed, and the original corrosion resistance of the plating is impaired.

  As a countermeasure against the above problem, Japanese Patent Application Laid-Open No. 11-70594 proposes a method of applying a release agent to a portion where a rubber layer is not formed on the outer periphery of a shaft body subjected to electroless nickel plating. However, when the release agent is applied in this manner, adhesion failure may occur between the shaft body and the rubber layer depending on the molding method of the rubber layer. For example, when unvulcanized rubber is extruded and the shaft body is continuously passed through the crosshead die of the extruder to coat the unvulcanized rubber on the outer periphery of the shaft body, the part to which the release agent is applied and the rubber are Since it cannot adhere, the problem that the rubber | gum slip which causes said adhesion failure arises will generate | occur | produce.

  On the other hand, JP-A-62-135953 proposes to inactivate sulfur by oxidizing the surface of the plating film by subjecting the electroless nickel plating film to chromic acid treatment or heat treatment. ing. However, when oxidizing the surface of the nickel plating film, there is a problem that if the film thickness is thin, discoloration of the plating surface occurs during vulcanization, and if the film thickness is thick, discoloration of the surface and poor conductivity occur.

  Furthermore, regarding chromic acid treatment, wastewater facilities are not only costly but also in the direction of being abolished.

  The present invention has been made in view of the above circumstances. In a rubber roller having a vulcanized rubber layer on the outer periphery of a shaft body subjected to electroless nickel-phosphorus plating, the rubber is removed when the plating film is discolored and the rubber layer is removed. An object of the present invention is to provide a rubber roller that does not cause sticking and can be easily manufactured at low cost.

As a result of intensive investigations by surface analysis such as XPS (X-ray photoelectron spectroscopic analysis) on the cause of discoloration of the electroless nickel-phosphorous plating film and adhesion of rubber, or peeling of the plating, the above-mentioned factors are The chemical reaction between the nickel component and the sulfur component as a vulcanizing agent was determined. As a result of further investigation, by forming trinickel monophosphide (Ni ₃ P) in the electroless nickel-phosphorous plating film, the reaction between the sulfur component contained in the rubber and the nickel component in the plating is suppressed. The present inventors have found that discoloration of the plating film and adhesion of vulcanized rubber can be prevented.

That is, the present invention provides at least one of a plating film containing at least phosphorus and nickel formed by electroless nickel-phosphorus plating on a shaft, and a vulcanizing agent containing sulfur or a sulfur atom in the molecular structure on the plating film. In a rubber roller having a rubber layer formed by vulcanizing an unvulcanized rubber composition to which one is added, trinickel monophosphate (Ni ₃ P) is present in the plating film on the shaft body. It is a featured rubber roller. Furthermore, trinickel monophosphide (Ni ₃ P) can be efficiently formed when the phosphorus content in the plating film is 8% by mass to 20% by mass.

Since the rubber roller of the present invention has trinickel phosphide (Ni ₃ P) in the plating film on the shaft body subjected to electroless nickel-phosphorus plating, the outer periphery of the shaft body subjected to electroless nickel-phosphorus plating Even when vulcanized after coating an unvulcanized rubber composition containing at least one of sulfur or molecular structure containing a sulfur atom on the surface, discoloration and rubber sticking on the plating film may occur. In addition, plating peeling does not occur when the rubber in the rubber layer non-formed part is removed. Therefore, it is possible to provide a rubber roller that does not affect the corrosion resistance, conductivity, etc., and that is low in cost and good in workability.

  Hereinafter, the present invention will be described in detail.

  In the present invention, first, a shaft body subjected to electroless nickel-phosphorus plating is used. The shaft body is not particularly limited, and can be used even if it is hollow or solid. Also, the material is not particularly limited, and conventionally known materials such as iron or steel can be used for rubber roller production.

  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-phosphorus 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 not easily generated, so that the corrosion resistance is excellent.

In the present invention, an electroless nickel-phosphorus 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 2% by mass to 20% by mass depending on conditions such as the concentration, composition, pH, plating temperature and time of the plating solution. The content can be changed. The higher the phosphorus content, the better the wear resistance and corrosion resistance. However, since the film becomes brittle, it seems that the practicality is poor at 20% by mass or more.

On the other hand, phosphorus in the film reacts with nickel by applying energy and crystallizes to form trinickel monophosphide (Ni ₃ P) (for example, Non-Patent Document 1). The discoloration of the electroless nickel film and the rubber fixation are caused by a chemical reaction between the nickel component in the film and the sulfur component in the rubber. This is a reaction between the simple nickel component and the sulfur component. Does not react. Furthermore, since simple nickel changes to trinickel monophosphide (Ni ₃ P) through crystallization, the absolute amount of simple nickel is reduced, and the reaction with the sulfur component can be suppressed. Trinickel monophosphide (Ni ₃ P) has the properties of an interstitial compound, and therefore has no adverse effect on wear resistance, corrosion resistance, and 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 8% by mass, the nickel component and the phosphorus component are precipitated in a stable crystal state during plating, and the reaction between the nickel component and the phosphorus component is difficult because the phosphorus content is small. . Accordingly, a considerable amount of energy is required to obtain the amount of trinickel phosphide (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 8% by mass or more, since the plating film is deposited in an amorphous state, the reaction between the nickel component and the phosphorus component is likely to proceed, and one of the amounts necessary for exhibiting the effects of the present invention. Trinickel phosphide (Ni ₃ P) can be easily formed. Therefore, if the phosphorus content in the plating film is 8% by mass or more, the effect of the present invention can be obtained, but if it exceeds 20% by mass, the original characteristics of plating are lost, and the corrosion resistance and wear resistance are remarkably increased. descend. From the above viewpoint, the electroless nickel-phosphorous plating applied to the shaft body of the rubber roller of the present invention preferably has a phosphorus content in the plating film of 8% by mass to 20% by mass, and 8% by mass to 16% by 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 of forming trinickel monophosphide (Ni ₃ P) is not particularly limited as long as it can provide phosphorus necessary for activating and crystallizing 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.

Heating can be performed without any problem in any atmosphere. However, when there is a concern about problems due to oxidation of the electroless nickel-phosphorous plating film surface, 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. If 200 ° C. or higher, the process proceeds activation of phosphorus in the plating film, 200 ° C. to 700 ° C. is preferably used as a heating temperature since the crystallization of the monophosphate of three nickel (Ni ₃ P) proceeds more satisfactorily Is done. For example, when the shaft body is iron, the shaft body may be deformed at 600 ° C. or higher and cannot be used as the shaft body of the rubber roller. In addition, work management becomes difficult under high temperature conditions. From the above points, 200 ° C to 300 ° C is more preferable.

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 not particularly specified, but the upper limit is the state in which all the phosphorus in the plating film has reacted to become trinickel monophosphide (Ni ₃ P), depending on the phosphorus content in the plating film. Is the upper limit. Also, the lower limit is that if the content of trinickel phosphide (Ni ₃ P) in the plating film is 3% by mass or more, discoloration of the plating surface does not occur, and the rubber layer does not adhere to the plating surface. It was.

  The rubber composition coated on the shaft in the rubber roller of the present invention is not particularly limited as long as sulfur or a vulcanizing agent containing a sulfur atom in the molecular structure is added. For example, ethylene-propylene- Diene copolymer rubber (EPDM), natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), epichlorohydrin rubber (CO, ECO, GECO) ) And acrylic rubber (ACM), and any rubber composition based on any polymer species can be used without any problem.

  The vulcanizing agent added to the rubber composition is not particularly limited as long as it contains a sulfur atom, and conventionally known vulcanizing agents are used. In addition to adding sulfur directly, a sulfur donor, triazine thiol and 2,3 dimethylquinoxaline may be used. Examples of the sulfur donor include tetramethyl thiuram disulfide (TETD), tetrabutyl thiuram disulfide (TBTD), dipentamethylene thiuram disulfide (TRA), 2- (4′-morpholinodithio) benzothiazole (MDB) 4-4 ′. -Dithiodimorpholine etc. are mentioned. The addition amount is not particularly limited as long as it satisfies the characteristics required for the rubber roller, but usually it is preferably used in an amount of 0.05 to 5 parts by mass per 100 parts by mass of the rubber component.

  The rubber layer of the rubber roller in the present invention is formed by placing an unvulcanized rubber composition on a cored bar and then vulcanizing on the cored bar. The means for placing the unvulcanized rubber on the mandrel is not particularly limited, but from the viewpoint of reducing the production line continuation or the production cost, an unvulcanized rubber composition is used by using an extruder. A method in which the core is continuously passed through the crosshead die of the extruder at the same time as the extrusion and the rubber composition is arranged on the circumference of the core to form a roller is particularly preferable. The vulcanization method is not particularly limited, and can be performed by a conventionally known method such as hot-air furnace vulcanization or far-infrared vulcanization. Alternatively, a core metal coated with unvulcanized rubber may be filled in a mold cavity and vulcanized.

EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not limited at all by these examples.
<Create shaft>
Electroless nickel-phosphorus plating is applied to a steel shaft with a diameter of 6 mm and a length of 240 mm. The phosphorus content in the plating film is adjusted by selecting the type of plating solution, and the plating film thickness is 3 to 6 μm. did. Formation of trinickel monophosphide (Ni ₃ P) in the plating film was carried out by supplying N 2 gas at 1 dm ³ / min. The sample was taken out by heating at 250 ° C. for 3 hours while being introduced, and was taken out when the furnace temperature became 80 ° C. or lower. Also, for the ratio Comparative Examples 3 was carried out under the same conditions using a hot-air furnace in the atmosphere.
<Creation of rubber composition>
Epichlorohydrin rubber (trade name: Epichromer CG102, manufactured by Daiso Corporation), 100 parts by mass, zinc oxide (trade name: 2 types of zinc oxide, manufactured by Hakusuitec Co., Ltd.), stearic acid (trade name: stearic acid S, manufactured by Kao Corporation) 1 part by mass, carbon black (trade name: manufactured by Asahi 15 Asahi Carbon Co., Ltd.), 5 parts by mass, calcium carbonate (trade name: manufactured by Silver W Shiroishi Kogyo Co., Ltd.), 40 parts by mass, dibenzothiazyl disulfide (trade name: Noxeller DM Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass, tetramethylthiuram monosulfide (trade name: Noxeller TS Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass, sulfur (trade name: Sulfax 200S Tsurumi Chemical Co., Ltd.) ) 1 part by mass is kneaded using a closed kneader and an open roll machine. To obtain a vulcanized rubber composition.
<Create rubber roller>
The unvulcanized rubber composition described above is extruded on the outer periphery of the shaft body by extruding the unvulcanized rubber composition into a cylindrical shape using an extruder and simultaneously passing the shaft body through a crosshead die. After covering the vulcanized rubber, a rubber roller having a vulcanized rubber layer was prepared by heating in a hot air oven at 180 ° C. for 1 hour. Further, while rotating this roller, a cutter blade was inserted at a position of 10 mm from both ends, and the rubber layers at both ends of the shaft body were removed. Those that could be removed were further set in a polishing machine equipped with a grinding wheel GC80 and polished so that the outer diameter was Φ8.5 mm at a rotational speed of 2000 rpm and a feed speed of 150 mm / min. .
<Evaluation method>
The rubber layer of the rubber roller obtained by the above method was peeled off, and the case where no discoloration or rubber sticking was observed on the plating film was marked with ◯. In addition, even when there is no discoloration and rubber sticking, if the adhesion of the plating film is confirmed on the peeled rubber layer, it is judged that a chemical reaction between the nickel component in the plating film and the sulfur component in the rubber has occurred. It was.
<Measurement of phosphorus content in electroless nickel-phosphorus plating film>
The phosphorus content was quantitatively analyzed by energy dispersive X-ray analysis (Hitachi, Ltd. S-4300, Edax Japan Co., 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 electroless nickel coating>
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 °.

In Comparative Examples 1 and 2, the phosphorus content in the plating film was 8% by mass or less, and the results were evaluated on those heated at 250 ° C. for 3 hours in an N ₂ atmosphere. At this time, although the comparative example 2 was lighter, the rubber sticking on the plating film was confirmed. Comparative Example 3 is a result of evaluating the same shaft body as that of Comparative Example 2 heated in a hot stove. Also in this case, as in Comparative Example 2, it was confirmed that the rubber adhered to the plating film.

  Comparative Examples 4 and 5 are the results of evaluation of the plating as it is when the phosphorus content in the plating film is 8 mass% to 16 mass%. At this time, in Comparative Example 4, rubber adhesion on the plating film was confirmed, but in Comparative Example 5, discoloration and rubber adhesion did not occur, but adhesion of the plating film to the peeled rubber layer was confirmed. In Comparative Examples 1 to 4, an accurate resistance value could not be measured because the rubber layers at both ends could not be removed.

Claims (10)

At least one of a plating film containing at least phosphorus and nickel formed by electroless nickel-phosphorous plating on the shaft body and sulfur or a vulcanizing agent containing a sulfur atom in the molecular structure was added to the plating film. In a rubber roller having a rubber layer formed by vulcanizing an unvulcanized rubber composition,
A rubber roller comprising a layer containing trinickel monophosphide (Ni ₃ P) crystals on a surface of a plating film on the shaft body.   The rubber roller according to claim 1, wherein a phosphorus content in the plating film is 8% by mass to 20% by mass. 3. The rubber roller according to claim 1, wherein the content of the crystal of trinickel monophosphide (Ni ₃ P) is 3% by mass to 70% by mass.   The rubber according to any one of claims 1 to 3, wherein the rubber layer is a rubber layer formed by directly vulcanizing an unvulcanized rubber composition on the outer periphery of the shaft body. roller.   The unvulcanized rubber composition is formed by extruding the unvulcanized rubber composition and simultaneously passing the shaft body through a crosshead die of an extruder so as to cover the outer periphery of the shaft body. The rubber roller according to claim 4, wherein the rubber roller is a vulcanized rubber composition. The rubber roller according to claim 5, wherein rubber layers at both ends of the shaft body are removed. Forming a plating film containing at least nickel and phosphorus by electroless nickel-phosphorus plating on the shaft body;
Forming a layer containing trinickel monophosphide (Ni ₃ P) crystals on the surface of the plating film by applying energy to the plating film;
Then, the unvulcanized rubber composition added with at least one of sulfur or a vulcanizing agent containing a sulfur atom in the molecular structure was formed on the plating film formed on the shaft body by vulcanization. Forming a rubber layer;
A method for producing a rubber roller, comprising: The method for producing a rubber roller according to claim 7 , wherein the energy is given by heat treatment. The method for producing a rubber roller according to claim 8 , wherein the heat treatment is performed in an inert atmosphere or a reducing atmosphere. Method for producing a rubber roller according to claim 9, wherein the heat treatment is at a temperature of 200 ℃ ~ 3 00 ℃.