Rubber cross-linked product and paper feeding roller

Abstract

To provide a rubber cross-linked product capable of suppressing the increase in cost, the rise in 100% modulus, and the occurrence of blooming / bleeding phenomena caused by the blending of carbon nanotubes, and a paper feeding roller.SOLUTION: A rubber cross-linked product comprises a polymer component. The polymer component comprises ethylene propylene diene rubber and / or ethylene propylene rubber as a main component. The rubber cross-linked product further comprises a donor-acceptor molecular compound and carbon nanotubes. The donor-acceptor molecular compound is represented by formula (1).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cross-linked rubber product and a paper feed roll. [Background technology]

[0002] Ethylene propylene diene rubber and / or ethylene propylene rubber, which does not have a double bond in the molecular backbone, is characterized by excellent heat resistance, ozone resistance, and light resistance. For this reason, ethylene propylene diene rubber and / or ethylene propylene rubber are used for packing, hoses, electric wires, belts, etc., and are particularly widely used in office automation (OA) equipment such as electrostatic copiers, laser printers, and facsimiles, as well as paper feed rolls for automatic teller machines (Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-101958 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-314019 [Patent Document 3] Japanese Utility Model Application Publication No. 3-95345 Summary of the Invention [Problem to be solved by the invention]

[0004] As mentioned above, ethylene propylene diene rubber and / or ethylene propylene rubber have excellent heat resistance, ozone resistance, and light resistance because they do not have double bonds in their molecular backbones. On the other hand, ethylene propylene diene rubber and / or ethylene propylene rubber have low polarity and higher electrical resistance than, for example, urethane. Therefore, "cross-linked rubber products containing a polymer component primarily composed of ethylene propylene diene rubber and / or ethylene propylene rubber" have sometimes been prone to attracting dust and other foreign matter from the atmosphere due to static electricity. In particular, when "cross-linked rubber products containing a polymer component primarily composed of ethylene propylene diene rubber and / or ethylene propylene rubber" are used as materials for paper feed rolls, the paper feed roll can become statically charged due to friction between the paper and the paper feed roll during paper feed. This can lead to paper dust adhering to the paper feed roll surface and a decrease in the friction coefficient of the paper feed roll. It is desirable for the friction coefficient of the paper feed roll to remain constant in order to facilitate paper feed. Therefore, it is desired to make the "cross-linked rubber product containing a polymer component mainly composed of ethylene propylene diene rubber and / or ethylene propylene rubber" less susceptible to electrostatic charge. In other words, it is desired to keep the volume electrical resistivity of the "cross-linked rubber product containing a polymer component mainly composed of ethylene propylene diene rubber and / or ethylene propylene rubber" low.

[0005] As a method for lowering the volume electrical resistivity of "a cross-linked rubber product containing a polymer component whose main component is ethylene propylene diene rubber and / or ethylene propylene rubber," for example, a method using conductive carbon black is known (Patent Document 3). In this disclosure, "conductive" means electrical conductivity. Conductive carbon black can be easily mixed with ethylene propylene diene rubber and / or ethylene propylene rubber, which have low polarity, and the conductive carbon black can reduce the volume electrical resistivity of the cross-linked rubber product. However, in order to reduce the volume electrical resistivity of the cross-linked rubber product by blending conductive carbon black (more specifically, for example, to reduce the volume electrical resistivity to 10 13In order to keep the electrical resistance to Ω·cm or less, it is necessary to increase the amount of conductive carbon black compounded in the cross-linked rubber (more specifically, for example, the amount needs to be 10 parts by mass or more per 100 parts by mass of rubber). If the amount of conductive carbon black compounded is 10 parts by mass or more per 100 parts by mass of rubber, the cross-linked rubber becomes dark black, which can make it difficult to color rubber products made from the cross-linked rubber. Furthermore, when the cross-linked rubber is used for a paper feed roll, the dark black color of the cross-linked rubber causes a problem in that white paper sheets are easily stained black when they rub against the paper feed roll.

[0006] Another known method for lowering the volume electrical resistivity of cross-linked rubber products containing a polymer component primarily composed of ethylene propylene diene rubber and / or ethylene propylene rubber is to incorporate an antistatic agent into the cross-linked rubber. However, antistatic agents generally have low compatibility with ethylene propylene diene rubber and / or ethylene propylene rubber, which have low polarity. Therefore, incorporating an antistatic agent into the cross-linked rubber product in the amount required to achieve antistatic effects can easily cause the bloom-bleed phenomenon, which can easily contaminate objects that come into contact with the cross-linked rubber product. In particular, when such cross-linked rubber products are used in paper feed rolls, the bloom-bleed phenomenon can cause problems such as paper sheet contamination, leading to poor printing and a decrease in the coefficient of friction of the paper feed roll. Therefore, there is a need to suppress the bloom-bleed phenomenon in cross-linked rubber products.

[0007] As yet another method for lowering the volume electrical resistivity of "a cross-linked rubber product containing a polymer component whose main component is ethylene propylene diene rubber and / or ethylene propylene rubber," a method of blending carbon nanotubes into the cross-linked rubber product is known (Patent Document 1, Patent Document 2). Carbon nanotubes are more effective at reducing the volume electrical resistivity of the cross-linked rubber product than conductive carbon black, and therefore the volume electrical resistivity of the cross-linked rubber product can be reduced with a smaller blending amount compared to the blending amount of conductive carbon black required to achieve this effect. However, in order to reduce the volume electrical resistivity of the cross-linked rubber product by blending carbon nanotubes (more specifically, to reduce the volume electrical resistivity to 10 13 In order to maintain the resistivity below Ω·cm, it is necessary to increase the amount of carbon nanotubes in the cross-linked rubber (more specifically, the amount must exceed 2.0 parts by mass per 100 parts by mass of rubber). Because carbon nanotubes are expensive, increasing the amount to exceed 2.0 parts by mass per 100 parts by mass of rubber significantly increases the compounding cost. At the same time, the modulus at 100% elongation (hereinafter also referred to as "100% modulus") of the cross-linked rubber significantly increases, making it difficult to properly maintain the physical properties (i.e., 100% modulus) of "a cross-linked rubber containing a polymer component primarily composed of ethylene propylene diene rubber and / or ethylene propylene rubber." In particular, when such a cross-linked rubber is used as a paper feed roll, a significant increase in the 100% modulus reduces the coefficient of friction between the paper feed roll and the paper sheets. Therefore, when using carbon nanotubes, it is necessary to keep the amount of carbon nanotubes low and effectively reduce the volume electrical resistivity of the cross-linked rubber.

[0008] According to the present disclosure, it is possible to provide a cross-linked rubber product that can suppress the increase in cost and the increase in 100% modulus due to the incorporation of carbon nanotubes, suppress the occurrence of the bloom-and-bleed phenomenon, keep the volume electrical resistivity low, and, when used in a paper feed roll, suppress the occurrence of staining of paper sheets due to the cross-linked rubber product, and a paper feed roll having a rubber layer made of the cross-linked rubber product. [Means for solving the problem]

[0009] The cross-linked rubber product according to one embodiment of the present disclosure is A cross-linked rubber product containing a polymer component, the polymer component is composed primarily of ethylene propylene diene rubber and / or ethylene propylene rubber, The cross-linked rubber further contains a donor-acceptor molecular compound and carbon nanotubes, The donor-acceptor molecular compound is represented by the following formula (1): the content of the donor-acceptor molecular compound is 0.5 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component, The content of the carbon nanotubes is 0.3 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polymer component. [ka] (In formula (1), R1 and R2 each independently represent CH3(CH2) 16 -CO-OCH2, CH3(CH2)9, CH3(CH2) 13 or HOCH2, R3 and R4 each independently represent CH3, C2H5, HOCH2, HOC2H4, or HOCH2CH(CH3), R5 represents C2H4, C3H6, or (CH2)9, and R6 represents CH3(CH2)9 or CH3(CH2) 16 indicates.) [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a cross-linked rubber product that can suppress the increase in cost and the increase in 100% modulus that would otherwise result from the incorporation of carbon nanotubes, suppress the occurrence of the bloom-and-bleed phenomenon, keep the volume electrical resistivity low, and, when used in a paper feed roll, suppress the occurrence of staining of paper sheets that would otherwise result from the cross-linked rubber product, and a paper feed roll that includes a rubber layer made of the cross-linked rubber product. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the shape of a paper feed roll according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram for explaining a part of a method for measuring the friction coefficient μ of a paper feed roll and a part of a method for measuring the size of a black stained area on a paper sheet caused by the paper feed roll. [Figure 3] FIG. 3 is a schematic cross-sectional view of a paper feed mechanism involved in the paper feed test. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. [1] The cross-linked rubber product of the present disclosure is A cross-linked rubber product containing a polymer component, the polymer component contains ethylene propylene diene rubber and / or ethylene propylene rubber as a main component, The cross-linked rubber further comprises a donor-acceptor molecular compound and carbon nanotubes, The donor-acceptor molecular compound is represented by the following formula (1): the content of the donor-acceptor molecular compound is 0.5 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polymer component, The content of the carbon nanotubes is 0.3 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polymer component. [ka] (In formula (1), R1 and R2 each independently represent CH3(CH2) 16 -CO-OCH2, CH3(CH2)9, CH3(CH2) 13 or HOCH2, R3 and R4 each independently represent CH3, C2H5, HOCH2, HOC2H4, or HOCH2CH(CH3), R5 represents C2H4, C3H6, or (CH2)9, and R6 represents CH3(CH2)9 or CH3(CH2) 16 indicates.)

[0013] This makes it possible to provide a cross-linked rubber product and a paper feed roll having a rubber layer made of the cross-linked rubber product, which can suppress the increase in cost and the increase in 100% modulus that would otherwise result from the incorporation of carbon nanotubes, suppress the occurrence of the bloom-and-bleed phenomenon, keep the volume electrical resistivity low, and, when used in a paper feed roll, suppress the occurrence of staining of paper sheets that would be caused by the cross-linked rubber product.

[0014] [2] In the above item [1], the content of the carbon nanotubes may be 0.8 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component. This makes it possible to provide a cross-linked rubber product that suppresses an increase in 100% modulus due to the incorporation of carbon nanotubes, suppresses the occurrence of the bloom-and-bleed phenomenon, keeps the volume electrical resistivity low, and, when used in a paper feed roll, can suppress the occurrence of staining of paper sheets due to the cross-linked rubber product, and a paper feed roll having a rubber layer made of the cross-linked rubber product.

[0015] [3] In the above [1] or [2], the carbon nanotubes may be single-walled carbon nanotubes. This makes it possible to provide a cross-linked rubber and a paper feed roll having a rubber layer made of the cross-linked rubber, which can suppress an increase in cost and an increase in 100% modulus due to the incorporation of carbon nanotubes, suppress the occurrence of the bloom-and-bleed phenomenon, keep the volume electrical resistivity low, and, when used in a paper feed roll, suppress the occurrence of staining of paper sheets due to the cross-linked rubber.

[0016] [4] In any of the above items [1] to [3], the content of carbon black is preferably less than 10 parts by mass per 100 parts by mass of the polymer component. This makes it possible to provide a cross-linked rubber product that, when used in a paper feed roll, can further suppress the occurrence of staining of paper sheets caused by the cross-linked rubber product, and a paper feed roll having a rubber layer made of the cross-linked rubber product.

[0017] [5] The paper feed roll of the present disclosure includes a rubber layer made of the cross-linked rubber described in [1] to [4] above.

[0018] This makes it possible to provide a paper feed roll having a rubber layer made of a cross-linked rubber product, which suppresses the increase in cost and 100% modulus due to the incorporation of carbon nanotubes, suppresses the occurrence of the bloom-bleed phenomenon, keeps the volume electrical resistivity low, and, when used in a paper feed roll, can suppress the occurrence of staining of paper sheets due to the cross-linked rubber product.

[0019] [Details of the embodiments of the present disclosure] An embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") will be described. However, the present embodiment is not limited thereto. In this specification, the notation in the format "A to Z" means the upper and lower limits of a range (i.e., A or more and Z or less). When no unit is specified for A and a unit is specified only for Z, the unit of A and the unit of Z are the same.

[0020] [Embodiment 1: Cross-linked rubber] A cross-linked rubber product according to one embodiment of the present disclosure will be described. The cross-linked rubber product of the present embodiment is A cross-linked rubber product containing a polymer component, the polymer component is composed primarily of ethylene propylene diene rubber and / or ethylene propylene rubber, The cross-linked rubber further contains a donor-acceptor molecular compound and carbon nanotubes, The donor-acceptor molecular compound is represented by the following formula (1): the content of the donor-acceptor molecular compound is 0.5 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component, The content of the carbon nanotubes is 0.3 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polymer component. [ka] (In formula (1), R1 and R2 each independently represent CH3(CH2) 16 -CO-OCH2, CH3(CH2)9, CH3(CH2) 13 or HOCH2, R3 and R4 each independently represent CH3, C2H5, HOCH2, HOC2H4, or HOCH2CH(CH3), R5 represents C2H4, C3H6, or (CH2)9, and R6 represents CH3(CH2)9 or CH3(CH2) 16 indicates.)

[0021] The present disclosure makes it possible to provide a cross-linked rubber product that can suppress the increase in cost and the increase in 100% modulus that would otherwise result from the incorporation of carbon nanotubes, suppress the occurrence of the bloom-and-bleed phenomenon, keep the volume electrical resistivity low, and, when used in a paper feed roll, suppress the occurrence of staining of paper sheets that would otherwise result from the cross-linked rubber product, and a paper feed roll that includes a rubber layer made of the cross-linked rubber product. The reasons for this are presumed to be as follows.

[0022] (a) The cross-linked rubber product according to this embodiment further contains carbon nanotubes, and the content of the carbon nanotubes is 0.3 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component. This keeps the amount of carbon nanotubes appropriately low, thereby minimizing the increase in cost and 100% modulus due to the incorporation of carbon nanotubes. Furthermore, carbon nanotubes can reduce the volume electrical resistivity without inducing the bloom-bleed phenomenon, thereby suppressing the bloom-bleed phenomenon in the cross-linked rubber product. Furthermore, because the parts by mass of carbon nanotubes are sufficiently low relative to the parts by mass of the polymer component, it is possible to suppress the occurrence of staining of paper sheets due to the cross-linked rubber product when used in a paper feed roll.

[0023] (b) The cross-linked rubber according to this embodiment further contains a donor-acceptor molecular compound, which is represented by the above formula (1), and the content of the donor-acceptor molecular compound is 0.5 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component. This allows the donor-acceptor molecular compound to enhance the effect of reducing volume electrical resistivity, even if the blending amount of carbon nanotubes, which have the effect of reducing volume electrical resistivity, is kept low.

[0024] As a result, it is possible to suppress the increase in cost and 100% modulus due to the incorporation of carbon nanotubes, suppress the occurrence of the bloom-bleed phenomenon, keep the volume electrical resistivity low, and, when used in paper feed rolls, suppress the occurrence of staining of paper sheets due to the cross-linked rubber.

[0025] <Polymer component> The polymer component is primarily composed of ethylene propylene diene rubber and / or ethylene propylene rubber. This allows the cross-linked rubber to have excellent weather resistance. The phrase "the polymer component is primarily composed of ethylene propylene diene rubber and / or ethylene propylene rubber" means that the total content of the ethylene propylene diene rubber and / or ethylene propylene rubber is 70 parts by mass or more per 100 parts by mass of the polymer component. The upper limit of the total content may be 100 parts by mass or less. The polymer component may be composed of ethylene propylene diene rubber and / or ethylene propylene rubber. The ethylene propylene diene rubber and / or ethylene propylene rubber may be non-oil-extended, oil-extended, or a mixture of non-oil-extended and oil-extended grades. The diene unit contained in the ethylene propylene diene rubber is not particularly limited, and may be, for example, ethylidene norbornene, 1,4-hexadiene, dicyclopentadiene, etc. In terms of a fast vulcanization rate, the diene unit may be ethylidene norbornene. The polymer component may contain only one type of ethylene propylene diene rubber and / or one type of ethylene propylene rubber, or may contain two or more types of ethylene propylene diene rubber and / or two or more types of ethylene propylene rubber. The polymer component may contain other polymer components as long as the main component is ethylene propylene diene rubber and / or ethylene propylene rubber. Examples of materials for the other polymer components include natural rubber, isoprene rubber, butadiene rubber, butyl rubber, styrene butadiene rubber, polynorbornene rubber, butadiene-nitrile rubber, chloroprene rubber, halogenated butyl rubber, acrylic rubber, and epichlorohydrin rubber.

[0026] The total content of the ethylene propylene diene rubber and / or ethylene propylene rubber is preferably 80 parts by mass or more per 100 parts by mass of the polymer component. This makes it easier to maintain the high weather resistance of the ethylene propylene diene rubber and / or ethylene propylene rubber. The lower limit of the total content of the ethylene propylene diene rubber and / or ethylene propylene rubber is more preferably 90 parts by mass or more. The upper limit of the total content of the ethylene propylene diene rubber and / or ethylene propylene rubber may be 100 parts by mass or less, 99 parts by mass or less, or 98 parts by mass or less. The total content of the ethylene propylene diene rubber and / or ethylene propylene rubber may be 80 parts by mass or more and 100 parts by mass or 90 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the polymer component.

[0027] <Crosslinking agent> The crosslinking agent is not particularly limited, but examples thereof include sulfur, sulfur-based organic compounds such as tetraalkylthiuranium disulfide, metal compounds such as magnesium oxide, organic peroxides, and resin crosslinking agents. The crosslinking agent may be sulfur, which is inexpensive, easily available, and has excellent abrasion resistance. Examples of organic peroxides (in other words, peroxide crosslinking agents) include dicumyl peroxide.

[0028] <Donor-acceptor molecular compounds> The cross-linked rubber further contains a donor-acceptor molecular compound. The donor-acceptor molecular compound is represented by the following formula (1). The content of the donor-acceptor molecular compound is 0.5 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component. This makes it possible to suppress the increase in cost and increase in 100% modulus that would result from the incorporation of carbon nanotubes in the cross-linked rubber, and also to keep the volume electrical resistivity low.

[0029] [ka] (In formula (1), R1 and R2 each independently represent CH3(CH2) 16 -CO-OCH2, CH3(CH2)9, CH3(CH2) 13 or HOCH2, R3 and R4 each independently represent CH3, C2H5, HOCH2, HOC2H4, or HOCH2CH(CH3), R5 represents C2H4, C3H6, or (CH2)9, and R6 represents CH3(CH2)9 or CH3(CH2) 16 indicates.)

[0030] In formula (1), R1 is CH3(CH2)9 and R2 is CH3(CH2) 13 Preferably, R3 is CH3, R4 is CH3, R5 is (CH2)9, and R6 is CH3(CH2)9. This makes it possible to further suppress the increase in cost and the increase in 100% modulus resulting from the incorporation of carbon nanotubes in the cross-linked rubber, and also makes it possible to further reduce the volume electrical resistivity.

[0031] The content of the donor-acceptor molecular compound may be 0.7 parts by mass or more and 2.0 parts by mass or less, 0.9 parts by mass or more and 2.0 parts by mass or less, or 1.0 parts by mass or more and 2.0 parts by mass or less, per 100 parts by mass of the polymer component.

[0032] <Carbon nanotubes> The cross-linked rubber further contains carbon nanotubes. The carbon nanotubes may be single-walled carbon nanotubes or multi-walled carbon nanotubes. Since the electrical conductivity of single-walled carbon nanotubes is higher than that of multi-walled carbon nanotubes, the carbon nanotubes are preferably single-walled carbon nanotubes, from the viewpoint of making it easier to keep the volume electrical resistivity of the cross-linked rubber low.

[0033] The lower limit of the average length of the carbon nanotubes is not particularly limited, but is preferably, for example, 5 μm or more, and the upper limit of the average length of the carbon nanotubes is not particularly limited.

[0034] The carbon nanotube content is 0.3 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component. This makes it possible to suppress increases in cost and 100% modulus due to the incorporation of carbon nanotubes in the cross-linked rubber, suppress the occurrence of the bloom-and-bleed phenomenon, keep the volume electrical resistivity low, and, when used in a paper feed roll, suppress the occurrence of paper staining due to the cross-linked rubber. From the viewpoint of further keeping the volume electrical resistivity low, the carbon nanotube content may be 0.5 parts by mass or more and 2.0 parts by mass or less, 0.8 parts by mass or more and 2.0 parts by mass or less, or 1.0 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component.

[0035] Carbon black The carbon black content is preferably less than 10 parts by mass relative to 100 parts by mass of the polymer component. This prevents the cross-linked rubber from turning dark black, making it impossible to color products made from the cross-linked rubber. Furthermore, when used as a paper feed roll, it is possible to prevent white paper sheets from becoming black and stained when the paper feed roll with the dark black rubber layer rubs against the white paper sheets. The carbon black content is preferably 0 parts by mass or more and less than 10 parts by mass relative to 100 parts by mass of the polymer component, more preferably 0 parts by mass or more and 5 parts by mass or less, even more preferably 0 parts by mass or more and 1 part by mass or less, and most preferably 0 part by mass.

[0036] Other ingredients Other components include, for example, softeners, vulcanization accelerators, vulcanization accelerator aids, scorch inhibitors, fillers, and antioxidants. Examples of softeners include paraffin-based petroleum-based blended oils with low naphthenic and aromatic component contents, poly-α-olefins, and long-chain alkyl carbonates. The amount of softener blended is not particularly limited and can be set appropriately. The vulcanization accelerator is not particularly limited and may be a thiazole such as dibenzothiazyl disulfide, a sulfenamide such as N-cyclohexyl-2-benzothiazole sulfenamide, a thiuram such as tetramethylthiuram disulfide, or a dithiocarbamate such as zinc dimethyldithiocarbamate. These vulcanization accelerators may be used alone or in combination of two or more. The amount of vulcanization accelerator blended is not particularly limited and can be set appropriately. Examples of vulcanization accelerators include metal oxides such as zinc oxide, fatty acids such as stearic acid and oleic acid, and zinc stearate. The content of the vulcanization accelerator is not particularly limited and can be set as appropriate. Examples of scorch inhibitors include maleic anhydride, thioimine compounds, sulfenamide compounds, and sulfonamide compounds. The amount of the scorch inhibitor is not particularly limited and can be set as appropriate. Examples of fillers include silica, calcium carbonate, magnesium carbonate, aluminum hydroxide, clay, talc, diatomaceous earth, mica, wood chips, and cork, as well as straw, bamboo, metal, glass, or polymer fibers. These fillers may be used alone or in combination. The amount of the filler is not particularly limited and can be set as appropriate. Examples of antioxidants include amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants. The amount of the antioxidant is not particularly limited and can be set as appropriate.

[0037] <Method for producing cross-linked rubber product> The cross-linked rubber product according to the present embodiment can be produced, for example, by the following method. First, a compound consisting of predetermined amounts of polymer components, carbon nanotubes, a donor-acceptor molecular compound, a cross-linking agent, and, if necessary, predetermined amounts of fillers, softeners, and other additives such as vulcanization accelerators, vulcanization accelerator aids, scorch inhibitors, and antioxidants is kneaded using a known kneading machine such as a kneader or open roll to obtain an unvulcanized rubber composition. When the rubber composition contains sulfur as a cross-linking agent, the rubber composition preferably contains a vulcanization accelerator. Next, the cross-linked rubber product according to the present embodiment can be obtained by vulcanizing the rubber composition under predetermined heating conditions. Examples of methods for vulcanizing the rubber composition include extrusion molding and transfer molding. For example, the rubber composition is introduced into a predetermined transfer molding mold and vulcanized (primary vulcanization) at a temperature of 140°C to 180°C for approximately 5 to 30 minutes, thereby simultaneously cross-linking the rubber composition and molding it into a tubular shape. If necessary, the tubular molded product (cross-linked rubber product) may be subjected to vulcanization (secondary vulcanization) at a temperature of 140°C to 190°C for approximately 30 to 180 minutes. This secondary vulcanization allows the volatilization of low-molecular-weight components that are prone to causing the bloom-bleed phenomenon. The tubular molded product (cross-linked rubber product) is then polished, for example, with a cylindrical polishing machine to the desired outer diameter and cut to the desired length, thereby obtaining a cross-linked rubber product of a shape suitable for a paper feed roll.

[0038] [Embodiment 2: Paper feed roll] A paper feed roll according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the shape of a paper feed roll according to an embodiment of the present disclosure.

[0039] The paper feed roll 10 of this embodiment includes a rubber layer 11 made of the cross-linked rubber described in the first embodiment.

[0040] The present disclosure makes it possible to provide a paper feed roll 10 having a rubber layer 11 made of a cross-linked rubber product, which can suppress the increase in cost and 100% modulus due to the incorporation of carbon nanotubes, suppress the occurrence of the bloom-and-bleed phenomenon, keep the volume electrical resistivity low, and, when used in a paper feed roll, suppress the occurrence of staining of paper sheets due to the cross-linked rubber product. The reasons for this are presumably as described in (a) and (b) above.

[0041] <Paper feed roll> The paper feed roll 10 of this embodiment includes a rubber layer 11 made of the cross-linked rubber product according to embodiment 1. Specifically, for example, the paper feed roll 10 of this embodiment is configured by inserting a core 12 into the rubber layer 11 made of the cross-linked rubber product according to embodiment 1 ( FIG. 1 ). The rubber layer 11 and the core 12 may be bonded together with an adhesive. The configuration of the paper feed roll 10 other than the material of the rubber layer 11, such as the shape of the paper feed roll 10 (e.g., cylindrical or D-shaped), the surface processing method (e.g., polishing, knurling, embossing, or uneven pattern), the thickness of the rubber layer 11, the material of the core 12, and the diameter of the core 12, may be the same as those typically used for paper feed rolls. The rubber layer 11 preferably constitutes the outermost layer of the roll that contacts the sheet material. Such a paper feed roll 10 can be used as a pickup roll, feed roll, or retard roll in office automation equipment, automatic teller machines, or the like.

[0042] <Rubber layer> The rubber layer 11 is made of the cross-linked rubber product according to embodiment 1. This makes it possible to provide a paper feed roll 10 including the rubber layer 11 made of the cross-linked rubber product, which can suppress an increase in cost and an increase in 100% modulus due to the incorporation of carbon nanotubes, suppress the occurrence of the bloom-and-bleed phenomenon, keep the volume electrical resistivity low, and, when used in a paper feed roll, can suppress the occurrence of staining of paper sheets due to the cross-linked rubber product.

[0043] ≪Applications≫ The paper feed roll according to this embodiment can transport not only paper but also various other sheet materials such as overhead projector sheets and plastic sheets.

[0044] <Manufacturing method of paper feed roll> The paper feed roll 10 according to this embodiment can be produced by a conventionally known method, except that the cross-linked rubber according to the first embodiment is used as the material for the rubber layer 11. [Example]

[0045] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0046] <<Preparation of cross-linked rubber and paper feed roll>> The cross-linked rubber products according to Samples 1 to 13 and Samples 101 to 139, and paper feed rolls having a rubber layer made of the cross-linked rubber products were produced as follows.

[0047] First, the following materials were prepared. <Material> First ethylene propylene diene rubber (EPDM): "EP22" (trademark) manufactured by ENEOS Second EPDM: ENEOS "EP107F" (trademark) Carbon black: Ketjenblack EC300J (trademark) manufactured by Lion Specialty Chemicals Co., Ltd. Donor-acceptor molecular compound: "BN-105" (trademark) manufactured by Boron Laboratory Co., Ltd. Carbon nanotubes: OCSiAl's single-walled carbon nanotubes "TUBALL SWCNT 93%" (trademark) Graphene: KISCO graphene powder "GNH-XZ (unmodified)" (trademark) Carbon fiber: Teijin Limited's milled fiber "HT M100 40MU" (trademark) Antistatic agent: "TBX-8310" (trademark) manufactured by Sanko Kogyo Co., Ltd. Stearic acid: Kao Corporation's "Lunac S-30" (trademark) Polyethylene glycol: "PEG#4000" (trademark) manufactured by Sanyo Chemical Industries, Ltd. Zinc oxide: "Zinc Oxide No. 1" (trademark) manufactured by Seido Chemical Co., Ltd. Long-chain dialkyl carbonate: Mitsui Fine Chemicals' "LIALCARB SR-1000 / R" (trademark) Paraffin-based petroleum-based blended oil (process oil): "PW90" (trademark) manufactured by Idemitsu Kosan Co., Ltd. Sulfur (crosslinking agent): "Sulfax A" (trademark), powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. First vulcanization accelerator: "Noccela DM" (trademark) manufactured by Ouchi Shinko Chemical Co., Ltd. Second vulcanization accelerator: "Noccela TRA" (trademark) manufactured by Ouchi Shinko Chemical Co., Ltd. Third vulcanization accelerator: "Noccela BZ" (trademark) manufactured by Ouchi Shinko Chemical Co., Ltd. Fourth vulcanization accelerator: "Noccela EZ" (trademark) manufactured by Ouchi Shinko Chemical Co., Ltd. Fifth vulcanization accelerator: "Noccela TTTE" (trademark) manufactured by Ouchi Shinko Chemical Co., Ltd. Peroxide crosslinking agent: NOF Corporation's "Perkmyl D" (trademark)

[0048] <Preparation of cross-linked rubber> Rubber compositions were obtained by mixing the ingredients shown in Tables 1 to 11 using a kneader. Next, the rubber compositions were subjected to vulcanization molding (primary vulcanization) using a sheet-shaped mold at 170°C for 15 minutes to obtain a 140mm x 180mm x 2mm sheet-shaped cross-linked rubber product. Note that for samples using sulfur as the cross-linking agent, secondary vulcanization was performed for 30 minutes at 170°C.

[0049] In this manner, cross-linked rubber products were produced according to Samples 1 to 13 and Samples 101 to 139. In Tables 1 to 11, the carbon nanotube content of 2.0 parts by mass or less means that the increase in cost due to the incorporation of carbon nanotubes is suppressed.

[0050] <Preparation of a paper feed roll having a rubber layer made of a cross-linked rubber> Rubber compositions were obtained by mixing the ingredients shown in Tables 1 to 11 using a kneader. Next, the rubber compositions were subjected to vulcanization molding (primary vulcanization) in a predetermined mold at 170°C for 15 minutes to obtain cylindrical cross-linked rubber products with an outer diameter of 21 mm, an inner diameter of 9 mm, and a length of 50 mm. For samples using sulfur as the cross-linking agent, secondary vulcanization was performed for 30 minutes at a temperature of 170°C. Next, this cross-linked rubber product was fitted into a core with a diameter of 10 mm and cut to a width of 10 mm. This was then inserted into a polyacetal resin shaft core as shown in Figure 1 as a rubber layer. The surface of the rubber layer was then polished to an outer diameter of 20 mm to produce paper feed rolls equipped with a rubber layer made of the cross-linked rubber product of each sample.

[0051] In this manner, paper feed rolls each having a rubber layer made of the cross-linked rubber products of Samples 1 to 13 and Samples 101 to 139 were produced.

[0052] [Table 1]

[0053] [Table 2]

[0054] [Table 3]

[0055] [Table 4]

[0056] [Table 5]

[0057] [Table 6]

[0058] [Table 7]

[0059] [Table 8]

[0060] [Table 9]

[0061] [Table 10]

[0062] [Table 11]

[0063] <Evaluation of cross-linked rubber properties> <Tensile strength> The tensile strength of the cross-linked rubber product for each sample was determined by carrying out a tensile test in accordance with JIS K6251. The measuring machine used was an autograph "AGS-X" (trademark) manufactured by Shimadzu Corporation. The shape of the sample was a No. 3 dumbbell. The results obtained are shown in the "Tensile strength [MPa]" column of Tables 1 to 11.

[0064] <Tear strength> The tear strength of the cross-linked rubber product for each sample was determined by carrying out a tear test in accordance with JIS K6252. The measuring machine used was an autograph "AGS-X" (trademark) manufactured by Shimadzu Corporation. The sample shape was an angle shape (no notch). The results obtained are shown in the "Tear strength [N / mm]" column of Tables 1 to 11.

[0065] <Young's modulus> The Young's modulus of the cross-linked rubber product for each sample was measured by the following method. The Young's modulus of the cross-linked rubber product was determined by carrying out a tensile test in accordance with JIS K6251. The measuring machine used was an autograph "AGS-X" (trademark) manufactured by Shimadzu Corporation. The shape of the sample was a No. 3 dumbbell. The tensile stress at an elongation strain of 1% and the tensile stress at an elongation strain of 10% were measured, and the slope of the line connecting these two points was calculated and taken as the Young's modulus. The results obtained are shown in the "Young's modulus [MPa]" column of Tables 1 to 10.

[0066] <100% modulus> The 100% modulus of the cross-linked rubber product of each sample was measured by the following method. The 100% modulus of the cross-linked rubber product was determined by conducting a tensile test in accordance with JIS K6251. The measuring machine used was an autograph "AGS-X" (trademark) manufactured by Shimadzu Corporation. The sample shape was a No. 3 dumbbell. The tensile stress at 100% elongation strain was measured, and this was taken as the 100% modulus. The results obtained are shown in the "100% Mod [MPa]" column of Tables 1 to 11. Furthermore, for the cross-linked rubber product of each sample, the difference [MPa] from the 100% modulus value of the cross-linked rubber product of Sample 101 (i.e., a cross-linked rubber product composed of a base component such as ethylene propylene diene rubber and not containing carbon nanotubes) was calculated by subtracting the 100% modulus value of the cross-linked rubber product of Sample 101 from the 100% modulus value of the cross-linked rubber product of that sample. The results are shown in the "Difference [MPa] from 100% Mod of Sample 101" column in Tables 1 to 11. The difference [MPa] from the 100% modulus of Sample 101 being 7.0 MPa or less means that the increase in 100% modulus due to the addition of carbon nanotubes was suppressed.

[0067] <Whether or not bloom and bleed occur> The paper feed rolls for each sample were left to stand for 168 hours under conditions of a temperature of 70°C and a humidity of 90%, and then the paper feed rolls were visually observed to determine whether or not the bloom-bleed phenomenon had occurred. The results obtained are shown in the "Presence or Absence of Bloom-Bleed" column of Tables 1 to 11. In the "Presence or Absence of Bloom-Bleed" column, "No" means that the occurrence of the bloom-bleed phenomenon had been suppressed.

[0068] <Black stains on paper sheets caused by paper feed rolls> For each sample paper feed roll, the degree of black staining of paper sheets by the paper feed roll was determined using the following method. First, the paper feed roll 10, test paper, and friction coefficient measurement jig were left for one hour at a temperature of 22°C and a humidity of 55% (Figure 2). Next, an 80 mm x 210 mm sheet of paper P (Fuji Xerox Co., Ltd., "Xerox 4200") connected to a load cell 30 was sandwiched between the paper feed roll 10, which was composed of a rubber layer 11 and a shaft core 12, and a Teflon (registered trademark) base plate 20. As shown by the vertical arrow in Figure 2, the paper feed roll 10 was pressed against the base plate 20 with a vertical load W (W = 250 gf). Next, the paper feed roll 10 was rotated in the direction indicated by arrow a in the figure at a peripheral speed of 300 mm / s for three seconds. After that, the degree of staining of the paper P on the contact surface with the paper feed roll 10 was visually confirmed. The evaluation criteria were as follows. The results obtained are shown in the "Black stains on paper sheets" column in Tables 1 to 11. An evaluation result of A means that the occurrence of stains on paper sheets caused by the cross-linked rubber was suppressed. (Evaluation criteria) A: The size of the black stains on the paper P that can be visually confirmed is 0.5 mm or less in width and 4 mm or less in length. B: The size of the visually confirmed black stain on the paper P is more than 0.5 mm in width and / or more than 4 mm in length.

[0069] <Paper feed test> The paper feed rolls for Samples 8 and 101 were mounted on a color multifunction printer (DocuCentre C6550I, manufactured by Fuji Xerox Co., Ltd.) and a paper feed test was conducted by running a Fuji Xerox "Xerox 4200" printer through the paper feed rolls. Figure 3 shows a cross-sectional schematic diagram of the paper feed mechanism of the multifunction printer used in the paper feed test. The paper feed mechanism includes a paper cassette containing a stack of paper (paper P) as a sheet material, a pickup roll 10P that contacts the leading edge of the upper surface of the paper P to feed the paper P from the paper cassette, and a separation mechanism 10S located downstream of the pickup roll 10P in the paper transport direction, which separates and transports the paper P fed from the pickup roll 10P one sheet at a time. The separation mechanism 10S includes a feed roll 10F (an example of a paper feed roller) and a retard roll 10R that is positioned below the feed roll 10F and presses against it. The retard roll 10R includes a rubber layer 11 and a torque limiter. The retard roll 10R is located below the feed roll 10F and is pressed against the feed roll 10F. The feed roll 10F is a drive roller that is driven by a drive source (not shown) to rotate around its axis, with the axis being perpendicular to the conveyance direction of the paper P. The feed roll 10F comes into contact with the top surface (front surface) of the paper P delivered from the paper cassette and is driven to rotate, thereby conveying the paper P downstream (see the dotted arrow in FIG. 3). A nip that holds the paper P delivered from the paper cassette is formed between the feed roll 10F and the retard roll 10R, and when multiple sheets of paper P are conveyed overlappingly through this nip, a torque limiter provided on the retard roll 10R applies conveyance resistance to the paper P from the bottom (back surface) side, preventing double feeding of the paper P conveyed by the feed roll 10F. The retard roll 10R is disposed in the separation mechanism 10S. To facilitate evaluation, the paper feed test and measurements were performed under an environment with a temperature of 10°C and a humidity of 15%, which is different from a normal room environment (e.g., a temperature of 22°C and a humidity of 55%) and where paper dust is likely to adhere to the paper feed roll due to paper feed. The paper feed roll, test paper, and paper feed tester were left in this environment for at least 24 hours before the paper feed test began. The paper feed rolls for each sample were used as the pickup roll 10P, feed roll 10F, and retard roll 10R, respectively.The sample used for the pickup roll 10P, the sample used for the feed roll 10F, and the sample used for the retard roll 10R were the same sample.

[0070] <Measurement of friction coefficient μ> The friction coefficient μ of the rubber layer of the paper feed rolls of Samples 8 and 101 was measured using the following method. First, the paper feed roll 10, the measurement paper, and the measurement jig were left for 24 hours at a temperature of 10°C and a humidity of 15% (FIG. 2). Next, a sheet of paper P (80 mm x 210 mm, manufactured by Fuji Xerox Co., Ltd., "Xerox 4200") connected to a load cell 30 was sandwiched between the paper feed roll 10, which was composed of the rubber layer 11 and the shaft core 12, and a Teflon (registered trademark) base plate 20. As shown by the vertical arrow in FIG. 2, the paper feed roll 10 was pressed against the base plate 20 with a vertical load W (W = 250 gf). Next, the paper feed roll 10 was rotated in the direction indicated by arrow a in the figure at a peripheral speed of 300 mm / s, and the force pulling the paper P, i.e., the generated friction force (force F indicated by the white arrow in FIG. 2), was measured with the load cell 30. The coefficient of friction μ was calculated from F [gf] and the load W [gf] using the following formula (2): The coefficient of friction μ was measured before the paper feed test and after 50 sheets of paper P had been fed in the paper feed test. Friction coefficient μ=F[gf] / W[gf] Equation (2) Next, based on the measured friction coefficient μ, the decrease in the friction coefficient μ between before and after the paper feed test was calculated. The decrease in the friction coefficient μ for Sample 8 was 0.247 for the pickup roll, 0.180 for the feed roll, and 0.233 for the retard roll. The decrease in the friction coefficient μ for Sample 101 was 0.793 for the pickup roll, 0.667 for the feed roll, and 0.627 for the retard roll. From the above, it was found that the paper feed roll for Sample 8 has an exceptionally excellent effect in suppressing the decrease in the friction coefficient between the paper feed roll 10 and the paper P compared to the paper feed roll for Sample 101.

[0071] <Volume electrical resistivity> The volume electrical resistivity of the cross-linked rubber of each sample was measured under the following conditions using a resistivity chamber "R12702A" (trademark) (main electrode diameter: 50 mm) manufactured by Nippon Denkei Co., Ltd. and an ultra-high resistance meter "8340A" manufactured by Advantest Corporation. The results obtained are shown in the "Volume electrical resistivity [Ω·cm]" column of Tables 1 to 11. Note that a volume electrical resistivity of 1.0×10 13 A resistivity of Ω·cm or less means that the volume electrical resistivity is kept low. (conditions) Charge time: 5 seconds Applied voltage: 50V

[0072] The cross-linked rubber products of Samples 1 to 13 correspond to Examples. The cross-linked rubber products of Samples 101 to 139 correspond to Comparative Examples. It was found that the cross-linked rubber products of Samples 1 to 13 suppressed the increase in cost and the increase in 100% modulus resulting from the blending of carbon nanotubes, suppressed the occurrence of the bloom-bleed phenomenon, and maintained a low volume electrical resistivity, compared to the cross-linked rubber products of Samples 101 to 139.

[0073] The differences between the Examples and the Comparative Examples are shown below in more detail. Sample 101: The compound contains only EPDM, zinc oxide, and a peroxide crosslinking agent, so the volume resistivity is 1.0 x 10 13 Greater than Ω·cm. Sample 102: Carbon black (conductive carbon black) is included in the formulation, but the content is low at 5.0 parts by mass per 100 parts by mass of the polymer component. In addition, donor-acceptor molecular compounds and carbon nanotubes are not included, so the volume electrical resistivity is 1.0 x 10 13 Greater than Ω·cm. Sample 103 and Sample 104: The compound contains 10.0 parts by mass or more of carbon black (conductive carbon black) per 100 parts by mass of the polymer component, so the volume electrical resistivity is 1.0 x 10 13Although the resistance was Ω·cm or less, compared to the paper feed rolls having a rubber layer made of the cross-linked rubber products of samples 1 to 13, the paper feed rolls having a rubber layer made of the cross-linked rubber products of samples 103 and 104 caused a greater degree of black staining of paper sheets due to the paper feed roll. Samples 105 to 111: Carbon fiber was included in the blend in an amount of 20.0 parts by mass or less per 100 parts by mass of the polymer component. However, the conductivity of the carbon fiber was low, and the donor-acceptor molecular compound and carbon nanotubes were not included. Therefore, the volume electrical resistivity was 1.0 × 10 13 Greater than Ω·cm. Samples 112 to 114: Carbon nanotubes are included in the formulation, but the content is low at 2.0 parts by mass or less per 100 parts by mass of the polymer component. In addition, no donor-acceptor molecular compounds are included, so the volume electrical resistivity is 1.0 x 10 13 Greater than Ω·cm. Sample 115: The compound contains 3.0 parts by mass of carbon nanotubes per 100 parts by mass of polymer components, so the volume electrical resistivity is 1.0 x 10 13 Although the resistance is below Ω·cm, the carbon nanotube content exceeds 2.0 parts by mass per 100 parts by mass of polymer, resulting in a significant increase in cost. Sample 116: The compound contains 5.0 parts by mass of carbon nanotubes per 100 parts by mass of polymer components, so the volume electrical resistivity is 1.0 x 10 13 Although the resistance is below Ω·cm, the carbon nanotube content exceeds 2.0 parts by mass per 100 parts by mass of the polymer component, resulting in a significant increase in cost. There is also a significant increase in the 100% modulus. Samples 117 to 121: The compound contains 10.0 parts by mass or less of graphene, a nanocarbon material similar to carbon nanotubes, per 100 parts by mass of polymer components. However, the conductivity of graphene is low, and the compound does not contain donor-acceptor molecular compounds or carbon nanotubes. Therefore, the volume electrical resistivity is 1.0 x 10 13 Greater than Ω·cm. Samples 122 and 123: The donor-acceptor molecular compound was contained in the blend in an amount of 2.0 parts by mass or less per 100 parts by mass of the polymer component. However, the conductivity of the donor-acceptor molecular compound was low, and no carbon nanotubes were contained. Therefore, the volume electrical resistivity was 1.0 x 10 13 Greater than Ω·cm. Samples 124 and 125: The donor-acceptor molecular compound was contained in the blend in an amount of 4.0 parts by mass or less per 100 parts by mass of the polymer component. However, the conductivity of the donor-acceptor molecular compound was low, and no carbon nanotubes were contained. Therefore, the volume electrical resistivity was 1.0 x 10 13 It is larger than Ω·cm. In addition, the content of donor-acceptor molecular compounds exceeds 2.0 parts by mass per 100 parts by mass of the polymer component, which makes it susceptible to blooming and bleeding. Sample 126: The blend contains 2.0 parts by mass of donor-acceptor molecular compounds per 100 parts by mass of polymer components. Graphene, a nanocarbon material like carbon nanotubes, is also included at 2.0 parts by mass per 100 parts by mass of polymer components. However, since no carbon nanotubes are included, the volume electrical resistivity is 1.0 x 10 13 Greater than Ω·cm. Samples 127 to 135: The donor-acceptor molecular compound is contained in the blend at 2.0 parts by mass or less per 100 parts by mass of the polymer component, and the carbon fiber content is 15.0 parts by mass or less per 100 parts by mass of the polymer component. However, since no carbon nanotubes are contained, the volume electrical resistivity is 1.0 x 10 13 Greater than Ω·cm. Sample 136: The compound contains 2.0 parts by mass of donor-acceptor molecular compounds per 100 parts by mass of polymer components, and 5.0 parts by mass of conductive carbon black per 100 parts by mass of polymer components. However, since no carbon nanotubes are included, the volume electrical resistivity is 1.0 x 10 13 Greater than Ω·cm. Samples 137-138: Although an antistatic agent is included in the formulation, the content is low at 10 parts by mass or less per 100 parts by mass of the polymer component, and donor-acceptor molecular compounds and carbon nanotubes are not included. Therefore, the volume electrical resistivity is 1.0 × 10 13 Greater than Ω·cm. Sample 139: The antistatic agent was contained in the formulation at 15 parts by mass per 100 parts by mass of the polymer component, so the volume electrical resistivity was 1.0 x 10 13 Although the resistance is Ω·cm or less, the content of antistatic agent exceeds 10 parts by mass per 100 parts by mass of polymer components, making it susceptible to blooming and bleeding.

[0074] On the other hand, in a cross-linked rubber product whose main polymer component is ethylene propylene diene rubber and / or ethylene propylene rubber, the donor-acceptor molecular compound contains a donor-acceptor molecular compound and carbon nanotubes, and the donor-acceptor molecular compound is represented by the above formula (1), the content of the donor-acceptor molecular compound is 0.5 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component, and the content of the carbon nanotubes is 0.3 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component (i.e., in Samples 1 to 13), it is possible to keep low the increase in cost and the increase in 100% modulus due to the incorporation of carbon nanotubes, to suppress the occurrence of the bloom-bleed phenomenon, to reduce the volume electrical resistivity, and, when used in a paper feed roll, to suppress the occurrence of staining of paper sheets due to the cross-linked rubber product.

[0075] Furthermore, it was found that the paper feed roll having a rubber layer made of the cross-linked rubber product of Sample 8 suppressed the decrease in the friction coefficient between the paper feed roll and the paper caused by the paper passing through, compared to the paper feed roll having a rubber layer made of the cross-linked rubber product of Sample 101. The reason for the suppression effect of the decrease in the friction coefficient is thought to be that the paper feed roll of Sample 8 suppressed the charging caused by the paper passing through and the adhesion of paper powder caused by the charging.

[0076] From the above, it was confirmed that in the cross-linked rubber products of Samples 1 to 13, the increase in cost and the increase in 100% modulus resulting from the incorporation of carbon nanotubes are suppressed, the occurrence of the bloom-and-bleed phenomenon is suppressed, the volume electrical resistivity is kept low, and when used in paper feed rolls, the occurrence of staining of paper sheets resulting from the cross-linked rubber is suppressed. Note that, although only ethylene propylene diene rubber is described as the polymer component in the examples, because there is no difference between ethylene propylene diene rubber and ethylene propylene rubber other than the presence or absence of a diene component, it is expected that the same effects will be achieved when the polymer component is ethylene propylene rubber and when the polymer component is ethylene propylene diene rubber and ethylene propylene rubber.

[0077] Although the embodiments and examples of the present invention have been described above, it is also planned from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined.

[0078] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the above-described embodiments and examples, and it is intended to include any modifications within the scope of the claims that are equivalent to the claims. [Explanation of symbols]

[0079] 10 Paper feed roll 10F Feed Roll 10S separation mechanism 10R retard roll 10P Pickup Roll 11 Rubber layer 12 axis 20 base plate 30 load cells P paper F Frictional force W load

Claims

1. A cross-linked rubber product containing a polymer component, the polymer component contains ethylene propylene diene rubber and / or ethylene propylene rubber as a main component, The cross-linked rubber further contains a donor-acceptor molecular compound and carbon nanotubes, The donor-acceptor molecular compound is represented by the following formula (1): the content of the donor-acceptor molecular compound is 0.5 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polymer component, The cross-linked rubber product, wherein the content of the carbon nanotubes is 0.3 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the polymer component. 【Chemical 1】 (In formula (1), R1 and R2 each independently represent CH ３ (CH ２ ) １６ -CO-OCH ２ , C.H. ３ (CH ２ ) ９ , C.H. ３ (CH ２ ) １３ , or HOCH ２ R3 and R4 each independently represent CH ３ , C ２ H ５ , HOCH ２ , H.O.C. ２ H ４ , or HOCH ２ CH (CH ３ ), and R5 is C ２ H ４ , C ３ H ６ , or (CH ２ ) ９ and R6 represents CH ３ (CH ２ ) ９ or CH ３ (CH ２ ) １６ Indicates.)

2. The cross-linked rubber product according to claim 1, wherein the content of the carbon nanotubes is 0.8 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polymer component.

3. The cross-linked rubber product according to claim 1 or 2, wherein the carbon nanotubes are single-walled carbon nanotubes.

4. 3. The cross-linked rubber product according to claim 1, wherein the content of carbon black is less than 10 parts by mass per 100 parts by mass of the polymer component.

5. A paper feed roll comprising a rubber layer made of the cross-linked rubber product according to claim 1 or 2.

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