JP2008058609A - Rubber roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber roller where the occurrence of a defect and the deterioration of quality resulting from adhesiveness between a rubber layer and a shaft body are restrained. <P>SOLUTION: The rubber roller has the shaft body having a plated coating film containing at least a nickel atom on its surface, and the rubber layer formed by vulcanizing unvulcanized rubber composition to which sulfur or a vulcanizing agent containing a sulfur atom in molecular structure is added on the outer peripheral surface of the shaft body. The plated coating film contains components other than nickel by less than 7 mass%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conductive rubber roller such as a charging roller, a developing roller, and a transfer roller, and a general rubber roller used in an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus typified by a copying machine, a printer, and a facsimile machine.

  Many rubber rollers such as a charging roller, a developing roller, and a transfer roller are used in electrophotographic apparatuses such as printers and facsimiles. These rubber rollers are generally composed of a shaft body and one or more vulcanized rubber layers formed on the outer peripheral surface thereof.

  The roller shaft used for the above application is usually made of metal, and the surface is plated. There are many platings such as brass plating and zinc plating, among which nickel plating is often used. Nickel plating includes electroless nickel plating using an electrochemical reaction and electroless nickel plating in which metal ions are reduced and deposited by a reducing agent contained in a plating solution without using electricity. 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 a reducing agent, phosphorus is mixed, and when a borohydride compound is used as a reducing agent, boron is mixed. On the other hand, when a reducing agent such as hydrazine or formalin is used, elements other than nickel may hardly be mixed. These platings are selected according to productivity, cost, and characteristics required for the product.

  As a method for fixing the vulcanized rubber layer on the outer peripheral surface of the shaft as described above, a method using an adhesive is common. For example, an adhesive is applied in advance to a part of a shaft body that forms a rubber layer, and a vulcanized rubber layer or an unvulcanized rubber layer is coated on the part, and then fixed through a bonding process such as heating. In order to obtain stable and strong adhesion, it is necessary to select an adhesive that is compatible with both the outer peripheral surface of the shaft body and the rubber material to be used, and the types are limited. Moreover, even if it is an adhesive agent excellent in adhesiveness, when application | coating thickness is non-uniform | heterogenous or an adhesive coating film peels in the process, there exists a problem of leading to poor adhesion. Furthermore, in order to obtain a stable processability, the adhesive is usually used by appropriately diluting with an organic solvent, so that environmental considerations are required.

  As a countermeasure for the above problem, for example, an unvulcanized rubber layer is formed directly on the outer peripheral surface of the shaft body subjected to electroless nickel plating, and vulcanized to form a vulcanized rubber layer. A method of adhering to the electroless nickel plating film has been proposed (see, for example, Patent Document 1). However, with this method, the adhesiveness varies greatly depending on the plating conditions and the number of plating turns applied to the outer peripheral surface of the shaft body, and the plating film is removed on the rubber layer side, and a part or the whole peels off to obtain good adhesiveness. There were cases where it was not possible. On the other hand, according to the patent document, it is said that the electroless nickel plating film preferably contains about 7 to 11% by mass of phosphorus and the balance is made of nickel, and the electroless nickel plating not satisfying this is particularly examined. It has not been.

JP-A-63-300041

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber roller that suppresses the occurrence of defects and deterioration in quality due to the adhesiveness between the shaft body and the rubber layer.

As a result of intensive studies focusing on the composition of the nickel plating film applied to the shaft body, the inventors have found that the smaller the content of components other than nickel, the stronger the plating film and vulcanized rubber layer are. It has been found that adhesion can be obtained, and the present invention has been completed.
That is, the present invention is formed by vulcanizing a shaft having a plating film containing at least nickel atoms on the surface and an unvulcanized rubber composition layer to which sulfur or a vulcanizing agent containing a sulfur atom in the molecular structure is added. In the rubber roller having a rubber layer on the outer peripheral surface of the shaft body, the plating film contains less than 7% by mass of components other than nickel.

  By providing a plating film containing less than 7% by mass of a component other than nickel on the surface of the shaft body, the shaft body and the rubber layer provided on the outer peripheral surface of the shaft body can be firmly bonded, and adhesion is improved. It is possible to suppress the occurrence of defective rubber rollers and deterioration in quality.

Hereinafter, the present invention will be described in detail.
In the present invention, first, a shaft having a plating film containing at least nickel atoms on the surface is prepared. The plating film needs to contain less than 7% by mass of components other than nickel. When a shaft having a plating film containing less than 7% by mass of a component other than nickel on the surface is used, unvulcanized rubber in which sulfur or a vulcanizing agent containing a sulfur atom in the molecular structure is added to the outer peripheral surface of the shaft When the rubber layer is formed by vulcanizing the composition, good adhesion can be obtained between the shaft and the rubber layer. When the plating film on the shaft body contains 7% by mass or more of components other than nickel, good adhesion cannot be obtained between the shaft body and the rubber layer formed on the outer peripheral surface thereof. . For this reason, for example, when an attempt is made to peel off the rubber layer, a part that partially peels off together with a part of the plating film appears. This phenomenon becomes more prominent as there are more components other than nickel in the plating film. In the plating film in which the components other than nickel exceed about 9% by mass, the entire rubber layer is peeled off together with a part of the plating film. In contrast, when the plating film contains less than 7% by mass of components other than nickel, such adhesion failure does not occur, and a strong adhesion to the rubber layer is obtained over the entire outer peripheral surface of the shaft body. Can do.

  It was formed by vulcanizing a shaft body having a plating film containing at least nickel atoms on its surface and an unvulcanized rubber composition to which sulfur or a vulcanizing agent containing sulfur atoms in the molecular structure was added as in the present invention. It is considered that the adhesion between the rubber layer and the outer peripheral surface of the shaft body appears as follows. That is, it is considered that adhesion is achieved by causing a chemical reaction between nickel atoms in the plating film and sulfur atoms contained in the unvulcanized rubber composition layer during heat vulcanization. On the other hand, the composition of the plating film changes depending on the conditions and the number of plating turns, and this changes the crystal characteristics of the plating film. For example, when the plating film is formed by electroless nickel-phosphorus plating, when the phosphorus content is less than 8% by mass, nickel in the plating film is precipitated in a microcrystalline state, but beyond that, the nickel is Amorphous precipitates. Therefore, if 8 mass% or more of components other than nickel are mixed in the nickel film, it is assumed that the plating film becomes brittle because it is amorphous. It is thought that it is done. From the above, when the plating film is formed by electroless nickel-phosphorus plating, the effect of the present invention appears if the content of components other than nickel in the plating film is less than 8% by mass. In order to obtain the effect of the present invention more reliably in the electroless nickel-phosphorous plating film and other plating films, it is preferable that the components other than nickel be less than 7% by mass.

  The plating film containing nickel atoms formed on the surface of the shaft body is preferably formed by electroless nickel-phosphorus plating, electroless nickel-boron plating, or electrolytic nickel plating, and has characteristics required for productivity, cost, and products. A suitable one is selected depending on the situation. In particular, in electrolytic nickel plating, it is easy to obtain a plating film in which components other than nickel are hardly mixed by appropriately selecting chemicals to be added to the plating solution. Although it is possible to suppress the inclusion of components other than nickel in the plating film by selecting a reducing agent even in the electroless plating method, it is practical because the reducing agent used is a hazardous substance such as formalin and hydrazine. poor. Therefore, at least 0.1% by mass or more of components other than nickel are mixed, but the plating film is preferably formed by electroless nickel plating, for example, electroless nickel-phosphorous plating or electroless nickel-boron plating. .

  The vulcanizing agent added to the unvulcanized rubber composition used in the present invention is not particularly limited as long as it contains a sulfur atom, and conventionally known vulcanizing agents are used. That is, there are methods using a combination of sulfur and a vulcanization accelerator, or using a vulcanizing agent containing a sulfur atom in the molecular structure without using sulfur.

  Examples of sulfur include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur and the like. These can be used alone or in combination of two or more. These addition amounts are preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the rubber component contained in the unvulcanized rubber composition.

  Examples of the vulcanizing agent containing a sulfur atom in the molecule include thiuram vulcanization accelerators such as tetramethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram disulfide, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, In addition to dithiocarbamate-based vulcanization accelerators such as zinc n-butyldithiocarbamate, 2- (4′-morpholinodithio) benzothiazole, 4,4′-dithiodimorpholine and the like can be mentioned. The addition amount is not particularly limited as long as it satisfies the characteristics required for the rubber roller, but is usually 0.05 parts by mass to 5 parts by mass per 100 parts by mass of the rubber component contained in the unvulcanized rubber composition. Preferably used between.

  The unvulcanized rubber composition is not particularly limited as long as sulfur or a vulcanizing agent containing a sulfur atom in the molecule 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 Any unvulcanized rubber composition mainly composed of any rubber component such as (CO, ECO, GECO) and acrylic rubber (ACM) can be used without any problem.

  The shaft used in the present invention is not particularly limited, and can be used without any problem even if it is hollow or solid. Further, the material is not particularly limited, and those conventionally known for rubber roller production such as iron or steel can be used.

  The rubber layer of the rubber roller of the present invention vulcanizes the unvulcanized rubber composition layer added with the sulfur or vulcanizing agent formed on the outer peripheral surface of the shaft having a plating film containing at least nickel atoms on the surface. It is preferable that it is formed by this. The means for forming the unvulcanized rubber composition layer to which the sulfur or vulcanizing agent is added on the shaft body is not particularly limited, but from the viewpoint of suppressing the continuation of the production line or the production cost. It is preferable to use the following means. Means for extruding the unvulcanized rubber composition and simultaneously passing the shaft through a crosshead die of an extruder to form the unvulcanized rubber composition layer on the outer peripheral surface of the shaft. It is preferable to be manufactured through. That is, the unvulcanized rubber composition containing sulfur (or vulcanizing agent) is extruded using an extruder, and at the same time, the shaft body is continuously passed through a crosshead die provided in the extruder. The unvulcanized rubber composition layer is formed on the outer peripheral surface of the shaft body to form a roller. A method of forming a rubber layer by vulcanizing the unvulcanized rubber composition layer is particularly preferable. The vulcanization method of the unvulcanized rubber composition layer added with the sulfur or vulcanizing agent formed on the outer peripheral surface of the shaft body is not particularly limited, and hot blast furnace vulcanization, far infrared vulcanization, etc. It can be performed by a conventionally known method. Further, there may be a method in which a shaft body coated with the unvulcanized rubber composition to which sulfur or a vulcanizing agent is added is filled in a mold cavity and vulcanized.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in detail, this invention is not limited at all by these examples. Further, in this embodiment, “part” represents “part by mass” and “%” represents “mass%” unless otherwise specified.

(Preparation of shaft body with plating film)
[Shaft body production example 1]
A steel shaft having a diameter of 6 mm and a length of 240 mm was prepared. Separately, nickel sulfate (nickel sulfate hexahydrate special grade, manufactured by Kanto Chemical Co., Ltd.) 0.1 mol / l, sodium hypophosphite (sodium hypophosphite monohydrate, special grade, manufactured by Kanto Chemical Co., Ltd.) ) The plating solution adjusted to 0.1 mol / l and sodium citrate (trisodium citrate dihydrate special grade, manufactured by Kanto Chemical Co., Ltd.) 0.4 mol / l was stirred while keeping at 80 ° C., and sulfuric acid ( The pH was adjusted to 8.0 using sulfuric acid special grade, manufactured by Kanto Chemical Co., Ltd.) and sodium hydroxide (sodium hydroxide special grade, manufactured by Kanto Chemical Co., Ltd.). Here, the steel shaft body was immersed for 20 minutes to form a plating film having a layer thickness of 5 μm on the surface of the shaft body, whereby shaft body A was obtained.

[Shaft body production example 2]
A shaft body B was obtained in the same manner as the shaft body manufacturing example 1 except that the nickel sulfate concentration was 0.05 mol / l and the pH was 6.5.

[Shaft body production example 3]
Nickel sulfate (nickel sulfate hexahydrate, special grade, manufactured by Kanto Chemical Co., Ltd.) 0.1 mol / l, sodium borohydride (sodium borohydride, manufactured by Kanto Chemical Co., Ltd.) 0.1 mol / l and sodium citrate (Trisodium citrate dihydrate, special grade, manufactured by Kanto Chemical Co., Ltd.) The plating solution adjusted to 0.4 mol / l was stirred while maintaining at 80 ° C., and sulfuric acid (sulfuric acid special grade, manufactured by Kanto Chemical Co., Ltd.) The pH was adjusted to 7.0 using sodium hydroxide (sodium hydroxide special grade, manufactured by Kanto Chemical Co., Inc.). A shaft body C was obtained in the same manner as the shaft body manufacturing example 1 except that the steel shaft body was plated by immersing the steel shaft body for 30 minutes.

[Shaft body production example 4]
Nickel sulfate 1.5 mol / l, nickel chloride (nickel chloride hexahydrate special grade, manufactured by Kanto Chemical Co., Ltd.) 0.5 mol / l and boric acid (boric acid special grade, manufactured by Kanto Chemical Co., Ltd.) 0.5 mol / l The mixture was stirred while maintaining 1 at 40 ° C., and adjusted to pH 3.0 using sulfuric acid. Then, a shaft body D was obtained in the same manner as the shaft body manufacturing example 1 except that the steel shaft body was immersed and plated under the condition of a current density of 3 A / dm ² .

[Shaft body production example 5]
A shaft body E was obtained in the same manner as the shaft body manufacturing example 1 except that the pH was 8.0.

[Shaft body production example 6]
A shaft body F was obtained in the same manner as the shaft body manufacturing example 1 except that the pH was 9.0.

[Shaft body production example 7]
A shaft body G was obtained in the same manner as the shaft body manufacturing example 1 except that the pH was 10.0.

[Shaft body production example 8]
In order to create a plating with a boron content of 7.0% or more, the addition of sodium borohydride was increased to 0.5 mol / l to create a shaft, but sodium borohydride itself was unstable. Because it was a chemical, it was deactivated during the plating reaction, or only about 1.8% was mixed in the plating film, and the desired shaft could not be obtained.

[Analysis of plating film]
The shaft body having the plating film obtained in the above-mentioned shaft body production example was sampled by dissolving and peeling it in an aqueous solution of metanitrobenzenesulfonic acid-ethylenediamine-sodium hydroxide to obtain a test sample. Quantitative analysis of the elements contained in these test samples was performed with a high frequency plasma emission spectrometer (ICP). The obtained results are shown in Table 1. In Table 1, as the main mixed elements, among the detected elements, those having a plating film composition of 0.1% by mass or more are described.

(Preparation example of unvulcanized rubber composition with sulfur and vulcanizing agent added)
(Unvulcanized rubber composition preparation example 1)
The following raw materials were prepared.
・ Epichlorohydrin rubber 100 parts [Product name: Epichromer CG102 manufactured by Daiso Corporation]
・ Zinc oxide 5 parts [Product name: Zinc oxide 2 types, manufactured by Hakusuitec Co., Ltd.]
・ Stearic acid 1 part [Product name: Stearic acid S manufactured by Kao Corporation]
・ Carbon black 5 parts [Brand name: Asahi # 15 Asahi Carbon Corporation]
・ 40 parts of calcium carbonate [Product name: Silver W manufactured by Shiroishi Kogyo Co., Ltd.]
・ Dibenzothiazyl disulfide 1 part [Product name: Noxeller DM Ouchi Shinsei Chemical Co., Ltd.]
・ Tetramethylthiuram monosulfide 1 part [Product name: Noxeller TS Ouchi Shinsei Chemical Co., Ltd.]
・ Sulfur 1 part [Product name: Sulfax 200S manufactured by Tsurumi Chemical Co., Ltd.]
Raw materials other than the vulcanizing agent and vulcanization accelerator were kneaded using a closed kneader (7 L pressure kneader, manufactured by Moriyama Co., Ltd.). First, only the polymer was kneaded for 1 minute at a rotor speed of 30 rpm, and then fillers and oil were added and kneaded for 15 minutes. The temperature of the rubber composition thus obtained was 96 ° C. After the rubber composition was cooled at room temperature (25 ° C.) for 12 hours, a vulcanizing agent and a vulcanization accelerator were further kneaded using an open roll machine (12 inch test roll machine, manufactured by Kansai Roll Co., Ltd.). . An unvulcanized rubber composition GC1 was obtained by kneading for 15 minutes at a front roll of 15 rpm and a back roll of 18 rpm as appropriate. The temperature of the rubber composition after kneading at this time was 52 ° C.

(Unvulcanized rubber composition preparation example 2)
The following raw materials were prepared.
-Ethylene-propylene-nonconjugated diene copolymer rubber 100 parts [Product name: EPT-4070, Mitsui Chemicals, Inc.]
・ Zinc oxide 5 parts [Product name: Zinc oxide 2 types, manufactured by Hakusuitec Co., Ltd.]
・ Stearic acid 1 part [Product name: Stearic acid S manufactured by Kao Corporation]
・ Carbon black 30 parts [Product name: Asahi # 15 Asahi Carbon Co., Ltd.]
・ Calcium carbonate 20 parts [Product name: Silver W manufactured by Shiroishi Kogyo Co., Ltd.]
・ 50 parts of paraffin oil [Product name: Diana Process Oil PW-380, manufactured by Idemitsu Kosan Co., Ltd.]
・ Dibenzothiazyl disulfide 1 part [Product name: Noxeller DM Ouchi Shinsei Chemical Co., Ltd.]
・ Tetramethylthiuram monosulfide 1 part [Product name: Noxeller TS Ouchi Shinsei Chemical Co., Ltd.]
・ Sulfur 1 part [Product name: Sulfax 200S manufactured by Tsurumi Chemical Co., Ltd.]
Raw materials other than the vulcanizing agent and vulcanization accelerator were kneaded using a closed kneader (7 L pressure kneader, manufactured by Moriyama Co., Ltd.). First, only the polymer was kneaded for 1 minute at a rotor speed of 30 rpm, and then fillers and oil were added and kneaded for 15 minutes. The temperature of the rubber composition thus obtained was 128 ° C. After the rubber composition was cooled at room temperature (25 ° C.) for 12 hours, a vulcanizing agent and a vulcanization accelerator were further kneaded using an open roll machine (12 inch test roll machine, manufactured by Kansai Roll Co., Ltd.). . An unvulcanized rubber composition GC2 was obtained by kneading with a front roll of 15 rpm and a back roll of 18 rpm for 15 minutes while turning appropriately. The temperature of the rubber composition after kneading at this time was 54 ° C.

(Example 1)
Unvulcanized rubber composition GC1 was supplied to an extruder equipped with a crosshead die (70 mm uniaxial vent type extruder, manufactured by Mitsuba Seisakusho). Extruding the unvulcanized rubber composition GC1 into a cylindrical shape at an extruder temperature control setting of 60 ° C. and a screw rotation speed of 5.0 rpm, and simultaneously passing the shaft body A through the crosshead die of the extruder. Thus, a layer of the unvulcanized rubber composition GC1 was formed on the outer peripheral surface of the shaft body A. A cutter blade was put into the layer of the unvulcanized rubber composition GC1 coated on both ends of the shaft body, and portions corresponding to 10 mm each of the both end portions were cut off to expose the shaft body, thereby producing roller bearing portions. The obtained roller was heated at 180 ° C. for 1 h in a hot air furnace to produce a rubber roller having a vulcanized rubber layer.

(Examples 2 to 4 and Comparative Examples 1 to 3)
Each rubber roller was produced in the same manner as in Example 1 except that each of the shaft bodies B to G for each Example and Comparative Example was used.

(Example 5-8, Comparative Example 5-7)
The unvulcanized rubber composition GC2 is supplied to an extruder equipped with a crosshead die, and the unvulcanized rubber composition GC2 is extruded into a cylindrical shape at a temperature control setting of the extruder of 60 ° C. and a screw rotation speed of 5.0 rpm. At the same time, each rubber roller was produced in the same manner as in Example 1 except that each of the shafts A to H for each Example and Comparative Example was continuously passed through the crosshead die of the extruder. .

(Comparative Examples 4 and 8)
As described above, the shaft body H did not have a plating film having properties that can be used practically. For this reason, it was not possible to produce a rubber roller using each of the unvulcanized rubber compositions GC1 and GC2 and the shaft body H.

(Rubber roller evaluation method)
For the five rubber rollers produced in each of the above examples and comparative examples, the rubber layer was peeled off with pliers and the adhesion between the shaft body and the rubber layer was evaluated. Based on the obtained results, the adhesiveness was evaluated according to the following criteria.
○: The rubber layer was firmly adhered to the entire surface of the shaft body when peeled. ×: The rubber layer was partially peeled together with a part of the plating film when peeled. XX: The rubber layer over the entire surface of the shaft body. Peeled

  In Examples 1 to 4 shown in Table 1 and Examples 5 to 8 shown in Table 2, each of the shaft bodies A to D was used, and in Examples 1 to 4, the unvulcanized rubber composition GC1 was changed to Examples 5 to 5. In No. 8, rubber rollers were prepared using the unvulcanized rubber composition GC2. From the results shown in Table 1 and Table 2, when a roller is produced using a shaft body in which the content of components other than nickel in the plating film is less than 7%, both when unvulcanized rubber compositions GC1 and GC2 are used The rubber layer formed by vulcanization was firmly bonded on the shaft, and no partial peeling was confirmed.

  On the other hand, Comparative Examples 1 to 3 shown in Table 1 and Comparative Examples 5 to 7 shown in Table 2 use shafts E to G, respectively, and electroless nickel-phosphorus plating is selected as the nickel plating, and the above plating film It is the result evaluated about the thing whose phosphorus content in 7% or more. The rubber layers formed by vulcanization in both Comparative Examples 1 and 5 using the unvulcanized rubber compositions GC1 and GC2 were firmly adhered to most of the shaft body, but partly plated. The adhesion failure which peels was confirmed. Further, as in Comparative Examples 2 and 6 and Comparative Examples 3 and 7, when the phosphorus content increases, the adhesiveness deteriorates, and even when the unvulcanized rubber compositions GC1 and GC2 are used, the rubber is almost entirely on the shaft body. The layer peeled. On the other hand, in Comparative Examples 4 and 8, an attempt was made to form a plating film having a boron content of about 7% by mass by electroless nickel-boron plating. Could not be evaluated.

Claims (4)

  A rubber layer formed by vulcanizing a shaft body having a plating film containing at least nickel atoms on the surface and an unvulcanized rubber composition layer to which a sulfur or a vulcanizing agent containing a sulfur atom in the molecular structure is added. The rubber roller which has on the outer peripheral surface of a body, The said plating film contains less than 7 mass% of components other than nickel, The rubber roller characterized by the above-mentioned.   2. The rubber roller according to claim 1, wherein the rubber layer is formed by vulcanizing the unvulcanized rubber composition layer formed on the outer peripheral surface of the shaft body.   Means for extruding the unvulcanized rubber composition and simultaneously passing the shaft through a crosshead die of an extruder to form the unvulcanized rubber composition layer on the outer peripheral surface of the shaft. The rubber roller according to claim 1, wherein the rubber roller is manufactured through a process.   4. The rubber roller according to claim 1, wherein the plating film is an electroless nickel-phosphorous plating film, an electroless nickel-boron plating film, or an electrolytic nickel plating film.