Rubber composition for paper feed member and paper feed roller

Abstract

To provide a rubber composition for a paper feed member that contains an ethylene-α-olefin-based resin excellent in ozone resistance and can sufficiently enhance an initial friction coefficient of a roller body or the like of a paper feed roller to a degree such as to cause no paper feed failure even after repeated paper feeding and can suppress degradation of abrasion resistance of the roller body or the like, and to provide a paper feed roller in which the roller body is made of the rubber composition for the paper feed member.SOLUTION: A rubber composition for a paper feed member contains rubber including ethylene-α-olefin-based copolymer rubber, a cross-linking component, and tackifier. The cross-linking component contains at least a sulfur-based cross-linking agent. The tackifier is an alkylphenol-based resin of 2 pts.mass or more and 15 pts.mass or less per 100 pts.mass of the total rubber amount. A roller body 2 of a paper feed roller 1 is made of the rubber composition for the paper feed member.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rubber composition for a paper feed member used to form a paper feed member such as a paper feed roller or a separation pad for feeding sheets in OA devices such as laser printers, and a paper feed roller including a roller body made of a crosslinked product of the rubber composition for the paper feed member.

Background Art

[0002] Paper feed members used in devices adopting an electrophotographic method such as laser printers are required to have excellent ozone resistance against ozone generated inside the device. As the rubber, EPDM with few unsaturated bonds and less prone to ozone degradation is preferably used (Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the sheets to be fed are papers with a lot of paper dust, etc., if the paper feeding continues, due to the accumulation of paper dust, the friction coefficient of the paper feed member may greatly decrease from the initial value, resulting in paper feeding failure. As a countermeasure, in order to suppress the occurrence of paper feeding failure even when the friction coefficient of the paper feed member decreases due to continuous paper feeding, it is conceivable to set the initial friction coefficient of the paper feed member to be relatively large.

[0005] Therefore, in Patent Document 1, a rubber composition prepared by blending an adhesion promoter together with a peroxide crosslinking agent for crosslinking EPDM (ethylene-propylene-diene copolymer rubber) is used to form a separation pad (anti-duplication rubber member) as a paper feeding member. However, since EPDM, which inherently has a low coefficient of friction, is used, it is difficult to significantly improve the coefficient of friction of the paper feeding member simply by blending an adhesion promoter.

[0006] That is, when a separation pad is formed using the rubber composition of Patent Document 1, the initial coefficient of friction can be increased to a range that can be used as a separation pad as described in Patent Document 1. However, a coefficient of friction in a higher range than that of the separation pad is required for the roller body of the paper feed roller, etc. among the paper feeding members.

[0007] Therefore, even if the roller body is formed using the rubber composition of Patent Document 1, the initial coefficient of friction of the roller body cannot be sufficiently increased to a range where paper feeding failure does not occur even when paper feeding is repeated. In addition, when the roller body is formed using the rubber composition of Patent Document 1, the wear resistance of the roller body may be significantly reduced.

[0008] An object of the present invention is to provide a rubber composition for a paper feeding member that contains an ethylene-α-olefin resin such as EPDM with excellent ozone resistance, and can sufficiently increase the initial coefficient of friction of the roller body of the paper feed roller, etc. to a range where paper feeding failure does not occur even when paper feeding is repeated, and can also suppress a decrease in the wear resistance of the roller body, etc. Another object of the present invention is to provide a paper feed roller formed with a roller body using such a rubber composition for a paper feeding member.

Means for Solving the Problems

[0009] The present invention relates to a rubber composition for a paper feeding member, which comprises a rubber containing an ethylene-α-olefin copolymer rubber, a crosslinking component for crosslinking the rubber, and a tackifier. The crosslinking component contains at least a sulfur-based crosslinking agent, the tackifier is an alkylphenol resin, and the proportion of the alkylphenol resin is 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the total amount of the rubber.

[0010] The present invention also relates to a paper feed roller comprising a roller body made of a crosslinked product of such a rubber composition for a paper feeding member.

Effects of the Invention

[0011] According to the present invention, it is possible to provide a rubber composition for a paper feeding member that contains an ethylene-α-olefin resin excellent in ozone resistance, and can sufficiently increase the initial friction coefficient of a roller body of a paper feed roller or the like to a range where paper feeding failure does not occur even when paper feeding is repeated, and can also suppress a decrease in wear resistance of the roller body or the like. Further, according to the present invention, it is possible to provide a paper feed roller formed by using such a rubber composition for a paper feeding member to form a roller body.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0013] 《Rubber Composition for Paper Feeding Member》 As described above, the rubber composition for a paper feeding member of the present invention comprises a rubber containing an ethylene-α-olefin copolymer rubber such as EPDM, a crosslinking component for crosslinking the rubber, and a tackifier, and the crosslinking component contains at least a sulfur-based crosslinking agent, and The tackifier is an alkylphenol resin, and the proportion of the alkylphenol resin is 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the total amount of the rubber. It is characterized by this.

[0014] According to the present invention, by crosslinking a rubber containing an ethylene-α-olefin copolymer rubber with a sulfur-based crosslinking agent, the effect of increasing the friction coefficient by blending an alkylphenol resin as a tackifier in the above-mentioned predetermined proportion can be further improved. Therefore, needless to say for the separation pad, even for the roller body of a paper feed roller etc. where a higher range of friction coefficient is required, the initial friction coefficient can be sufficiently increased to a range where paper feeding failure does not occur when paper feeding is repeated.

[0015] Moreover, according to the present invention, by crosslinking a rubber containing an ethylene-α-olefin copolymer rubber with a sulfur-based crosslinking agent, even if an alkylphenol resin as a tackifier is blended in the above-mentioned predetermined proportion, it is possible to suppress a large decrease in wear resistance. These are also clear from the results of Examples and Comparative Examples described later. 〈Rubber〉 As the rubber, various rubbers that can be crosslinked with a sulfur-based crosslinking agent and at least contain an ethylene-α-olefin copolymer rubber can be used.

[0016] Other rubbers that may be used in combination with the ethylene-α-olefin copolymer rubber include, for example, natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), fluororubber (FKM), chloroprene rubber (CR), silicone rubber (VMQ), urethane rubber (U), ethylene-propylene rubber, etc., one or more of these.

[0017] However, considering improving the ozone resistance, weather resistance, etc. of the roller body of the paper feed roller as a paper feed member, as the rubber, it is preferable to use only ethylene-α-olefin copolymer rubber (including the case of using two or more kinds of ethylene-α-olefin copolymer rubbers in combination). (ethylene-α-olefin copolymer rubber) Among the rubbers, as the ethylene-α-olefin copolymer rubber, various copolymer rubbers containing ethylene and α-olefin as copolymer components and crosslinkable with a sulfur-based crosslinking agent can be used, and in particular, a copolymer rubber of ethylene, α-olefin, and diene is preferable.

[0018] Examples of the diene constituting such a copolymer rubber include ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, etc., and as the α-olefin, propylene or butene is preferable. Examples of the ethylene-α-olefin-diene copolymer rubber include ethylene-propylene-diene copolymer rubber (EPDM), ethylene-butene-diene copolymer rubber (EBDM), ethylene-propylene-butene-diene copolymer rubber (EPBDM), etc.

[0019] In particular, EPDM having excellent crosslinkability with a sulfur-based crosslinking agent is preferable. · EPDM As EPDM, various copolymers obtained by copolymerizing ethylene, propylene, and diene can be used. Also, as EPDM, there are an oil-extended type in which extender oil is added to adjust flexibility and a non-oil-extended type in which no extender oil is added. In the present invention, any of these EPDMs may be used.

[0020] Specific examples of non-oil-extended EPDM include, but are not limited to, for example, the following various EPDMs. Esprene (registered trademark) 301, 301A, 501A, 502, 505, 505A, 512F, 532, 552, 586, 5206F, 5527F, etc. manufactured by Sumitomo Chemical Co., Ltd. NORDEL (registered trademark) IP3430, IP3640, IP3720P, IP3722P, IP3772P EL, IP3745P, IP3745P EL, IP3760P, IP4520, IP4570, IP4640, IP4725P, IP4760P, IP4770R, IP4770P, IP4770P EL, IP4770R EL, IP4785HM, IP4820P, IP5565, etc. manufactured by The Dow Chemical Company

[0021] EP21, EP51, EP25, EP123, EP103AF, EP107F, EP57F / C, EP93, etc. manufactured by JSR Corporation Mitsui EPT 1045, 1070, 2060M, 3045, 3070, 3091, 3092M, 3110M, 4070, X-3012P, 3092PM, etc. manufactured by Mitsui Chemicals, Inc. In addition, specific examples of oil-extended EPDM include, but are not limited to, the following various EPDMs.

[0022] Esprene 600F, 601F, 603, 670F, 6101, 7456, etc. manufactured by Sumitomo Chemical Co., Ltd. EP98, etc. manufactured by JSR Corporation Mitsui EPT X-3042E, etc. manufactured by Mitsui Chemicals, Inc. One or more of these non-oil-extended EPDMs and / or oil-extended EPDMs can be used.

[0023] When using an oil-extended type of rubber such as EPDM as the rubber, the ratio of various components such as the crosslinking component and the tackifier may be set by defining the amount of the rubber component as the solid content contained in the oil-extended type of rubber as the amount of the rubber. 〈Crosslinking component〉 As the crosslinking component, a sulfur-based crosslinking agent is used as described above.

[0024] Thereby, compared with the conventional crosslinking by a peroxide crosslinking agent, the effect of increasing the friction coefficient of the paper feeding member by blending an alkylphenol resin as a tackifier can be further improved. Therefore, as a paper feeding member, not only a separation pad but also a roller body of a paper feed roller or the like that requires a higher range of friction coefficient can sufficiently increase the initial friction coefficient to a range where paper feeding failure does not occur when paper feeding is repeated.

[0025] In addition, when an alkylphenol resin as an adhesion-imparting agent is blended, it is also possible to suppress a significant decrease in the wear resistance of the roller body or the like. (Sulfur-based crosslinking agent) Examples of sulfur-based crosslinking agents include sulfur such as powdered sulfur, oil-containing powdered sulfur, precipitated sulfur, colloidal sulfur, and dispersible sulfur, and organic sulfur-containing compounds such as tetramethylthiuram disulfide and N,N-dithiobismorpholine. In particular, sulfur is preferred.

[0026] Although the ratio of sulfur can be arbitrarily set, it is preferably 0.5 parts by mass or more and preferably 2 parts by mass or less per 100 parts by mass of the total amount of rubber. If the ratio of sulfur is less than this range, the crosslinking rate of the entire rubber composition for the paper feeding member becomes slow, the time required for crosslinking becomes long, and the productivity of the paper feeding member such as a paper feed roller may decrease.

[0027] Also, when the ratio of sulfur exceeds the above range, the compression set after crosslinking may increase, or excess sulfur may bloom on the surface of the paper feeding member. When using, for example, oil-containing powdered sulfur or dispersible sulfur as sulfur, the above ratio is the ratio of sulfur itself as the active ingredient contained therein. When an organic sulfur-containing compound is used as a crosslinking agent, its ratio is preferably adjusted so that the ratio of sulfur contained in the molecule per 100 parts by mass of the total amount of rubber is within the above range.

[0028] (Crosslinking accelerator) As a crosslinking component, in order to adjust the progress rate of the crosslinking reaction of rubber by a sulfur-based crosslinking agent, it is preferable to use a so-called crosslinking accelerator in combination. Examples of the crosslinking accelerator include one or more of inorganic accelerators such as slaked lime, magnesia (MgO), litharge (PbO), and various organic accelerators described below.

[0029] Guanidine-based accelerators such as 1,3-di-o-tolylguanidine, 1,3-diphenylguanidine, 1-o-tolylbiguanide, and the di-o-tolylguanidine salt of dicatecholborate. Thiazole-based accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyldisulfide.

[0030] Sulfenamide-based accelerators such as N-tert-butyl-2-benzothiazolylsulfenamide and N-cyclohexyl-2-benzothiazolylsulfenamide. Thiuram-based accelerators such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, and dipentamethylenethiuram tetrasulfide.

[0031] Dithiocarbamate-based accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, and zinc dibutyldithiocarbamate. Thiourea-based accelerators such as N,N′-diphenylthiourea, trimethylthiourea, and N,N′-diethylthiourea. The proportion of the crosslinking accelerator can be arbitrarily set depending on its type. Usually, per 100 parts by mass of the total amount of rubber, it is preferably 0.1 part by mass or more, particularly preferably 0.2 part by mass or more, and preferably 5 parts by mass or less, particularly preferably 3 parts by mass or less, individually.

[0032] 〈Alkylphenol resin〉 As the alkylphenol resin, various alkylphenol resins that can function as a tackifier for rubber can be used. Specific examples of the alkylphenol resin include, but are not limited to, for example, the following various alkylphenol resins.

[0033] TACKIROL (registered trademark) 130 [alkylphenol-formaldehyde resin], 160 [alkylphenol-acetaldehyde resin], EP-20 [alkylphenol-formaldehyde resin], EP-30 [alkylphenol-acetaldehyde resin], etc. manufactured by Tago Chemical Industry Co., Ltd. Tamanoal (registered trademark) 100S, 200N, 510, 521, 526, 586, 2800, 7509, etc. manufactured by Arakawa Chemical Industries, Ltd.

[0034] One or more of these alkylphenol resins can be used. As alkylphenol resins, for example, TACKIROL 201, 250-I, 250-III, AP, V-200, etc. manufactured by Tago Chemical Industry Co., Ltd. are also known as alkylphenol resins that function as crosslinking agents for rubbers such as EPDM (Patent Documents 2, 3, etc.). However, these alkylphenol resins have their properties such as acid value adjusted or are modified with halogens, etc., and none of them have the function of a tackifier, and even if blended, they cannot achieve the same effects as the present invention described above.

[0035] Moreover, since it may compete with sulfur-based crosslinking agents and there may be cases where ethylene-α-olefin-diene copolymer rubber cannot be crosslinked well, in the present invention, alkylphenol resins that function as crosslinking agents are not included (excluded). The proportion of the alkylphenol resin is limited to 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the total amount of the rubber, as described above.

[0036] If the proportion of the alkylphenol resin is less than this range, even though a sulfur-based crosslinking agent is used as the crosslinking component, it may not be possible to sufficiently increase the initial coefficient of friction of the roller body of the paper feed roller, etc. to a range where paper feed failure does not occur even when paper feeding is repeated. On the other hand, if the proportion of the alkylphenol resin exceeds the above range, not only will no further effect be obtained, but the processability of the rubber composition for the paper feeding member may also deteriorate.

[0037] That is, when preparing the rubber composition for the paper feeding member, it may become difficult to knead each component with a kneader, take it out from the kneader, or mold it into the shape of the roller body. On the contrary, by setting the proportion of the alkylphenol resin within the above range, while maintaining good processability, it is possible to sufficiently increase the initial coefficient of friction of the roller body of the paper feed roller, etc. to a range where paper feeding failure does not occur even when paper feeding is repeated.

[0038] In consideration of further improving such an effect, the proportion of the alkylphenol resin is preferably 3 parts by mass or more, particularly preferably 4 parts by mass or more, per 100 parts by mass of the total amount of rubber, and preferably 13 parts by mass or less, particularly preferably 12 parts by mass or less, even within the above range. 〈Filler〉 A filler may be blended in the rubber composition for the paper feeding member in order to improve the mechanical strength of the paper feeding member, etc. or to reduce the compounding cost of the rubber compound without affecting the properties of the paper feeding member.

[0039] Examples of the filler include one or more of carbon black, calcium carbonate, zinc oxide, silica, clay, talc, magnesium carbonate, aluminum hydroxide, titanium oxide, etc. In particular, in order to reduce the compounding cost of the rubber compound without affecting the properties of the roller body, it is preferable to use one or more of carbon black, calcium carbonate, clay, talc, magnesium carbonate, aluminum hydroxide, etc.

[0040] In addition, a small amount of carbon black may be used in combination with one or more of calcium carbonate, clay, talc, magnesium carbonate, aluminum hydroxide, etc. as a filler also serving as a colorant. When the rubber contains an oil-extended rubber such as oil-extended EPDM, the proportion of the filler depends on the amount of oil extension, but is preferably 20 parts by mass or more, particularly preferably 23 parts by mass or more, per 100 parts by mass of the total amount of the rubber, and preferably 30 parts by mass or less, particularly preferably 27 parts by mass or less.

[0041] When the rubber does not contain an oil-extended rubber, it is preferably 3 parts by mass or more, particularly preferably 5 parts by mass or more, per 100 parts by mass of the total amount of the rubber, and preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less. The proportion of carbon black as a filler also serving as a colorant is preferably 0.1 part by mass or more, particularly preferably 0.3 part by mass or more, per 100 parts by mass of the total amount of the rubber, and preferably 1 part by mass or less, particularly preferably 0.7 part by mass or less.

[0042] 〈Other Components〉 To the rubber composition, components generally compounded as additives in rubber compositions, such as a crosslinking aid, an antioxidant, a co-crosslinking agent, a pigment, a plasticizer, a processing aid, and a peptizer, may be added in an appropriate amount within a range that does not inhibit the effects of the present invention. (Crosslinking Aid) Among the above, examples of the crosslinking aid include metal compounds such as zinc oxide; fatty acids such as stearic acid, oleic acid, and cottonseed fatty acid; and one or more of other conventionally known crosslinking aids.

[0043] The proportion of the crosslinking aid is preferably 0.1 part by mass or more, particularly preferably 0.3 part by mass or more, per 100 parts by mass of the total amount of the rubber, and preferably 8 parts by mass or less, particularly preferably 6 parts by mass or less, individually. As described above, the rubber composition for a paper feeding member of the present invention can be used as a forming material for various paper feeding members for feeding sheet-like materials, such as paper feed rollers and separation pads.

[0044] In particular, it can be suitably used as a forming material for a paper feed roller that requires a friction coefficient in a range higher than that of the separation pad. 《Paper Feed Roller》 FIG. 1 is a perspective view showing a partially enlarged example of an embodiment of the paper feed roller of the present invention.

[0045] Referring to FIG. 1, the paper feed roller 1 in this example includes a roller body 2 formed by molding the above-described rubber composition for a paper feeding member into a cylindrical shape and crosslinking it. A through hole 3 having a circular cross-section is provided at the center of the roller body 2, and a cylindrical shaft 4 connected to a drive system (not shown) is inserted and fixed in the through hole 3. The outer peripheral surface 5 of the roller body 2 that contacts the paper is formed in a cylindrical shape concentric with the through hole 3 and the shaft 4 in the case of the example in the figure.

[0046] The roller body 2 and the shaft 4 are fixed to each other so as not to cause idling, for example, by press-fitting the shaft 4 having an outer diameter larger than the inner diameter of the through hole 3 into the through hole 3 of the roller body 2. That is, a certain idling torque (the limit torque at which idling does not occur) is ensured between the two based on the interference due to the diameter difference between the two.

[0047] The shaft 4 is formed of, for example, metal, ceramic, hard resin, or the like. A plurality of roller bodies 2 may be fixed to a plurality of locations on one shaft 4 as needed. The roller body 2 is manufactured by molding the rubber composition for a paper feeding member into a cylindrical shape by, for example, an extrusion molding method or the like and then crosslinking it by a press crosslinking method or the like, or by molding it into a cylindrical shape and crosslinking it by a transfer molding method or the like.

[0048] The roller body 2 may be polished so that the outer peripheral surface 5 has a predetermined surface roughness, or may be knurled, dimpled, or the like, as needed, at any point in the above manufacturing process. Also, both ends of the roller body 2 may be cut so that the outer peripheral surface 5 has a predetermined width. The roller body 2 may also be formed into a two-layer structure including an outer layer on the outer peripheral surface 5 side and an inner layer on the through hole 3 side.

[0049] In that case, it is preferable to form at least the outer layer with a crosslinked product of the rubber composition for a sheet feeding member of the present invention described above. However, considering simplifying the structure, improving productivity, reducing manufacturing costs, etc., the roller body 2 preferably has a single-layer structure made of a crosslinked product of the rubber composition for a sheet feeding member of the present invention, as shown in FIG. 1.

[0050] Also, the roller body 2 may have a porous structure. However, in order to increase the tensile strength, improve the wear resistance, reduce the compression set, and make it difficult for dents due to deformation to occur even when the state of contact at one point continues for a relatively long period, the roller body 2 preferably has a substantially non-porous structure. In order to achieve good paper feeding using the paper feed roller 1, the roller body 2 preferably has a Type A durometer hardness of A55 or less, particularly A50 or less.

[0051] Also, considering improving the wear resistance and reducing the compression set, the roller body 2 preferably has a Type A durometer hardness of A25 or more, particularly A30 or more. Depending on the use of the paper feed roller 1, the through hole 3 may be provided at a position eccentric from the center of the roller body 2.

[0052] Also, the outer peripheral surface 5 of the roller body 2 may not be cylindrical but may have a deformed shape, for example, a shape in which a part of the cylindrical outer peripheral surface 5 is cut out into a flat shape. To manufacture the paper feed roller 1 provided with the roller body 2 having these deformed shapes, the roller body 2 having the deformed shape may be directly molded by the manufacturing method described above, or the roller body 2 molded into a cylindrical shape may be made into a deformed shape by post-processing.

[0053] Also, a shaft 4 having a deformed shape corresponding to the deformed shape of the roller body 2 may be press-fitted into the through hole 3 of the roller body 2 molded into a cylindrical shape to deform the roller body 2 into a deformed shape. In this case, polishing, knurling, grooving, etc. of the outer peripheral surface 5 can be performed on the cylindrical outer peripheral surface 5 before deformation, so that the workability can be improved. The paper feed roller of the present invention can be incorporated into various OA devices using electrophotography, such as laser printers, electrostatic copiers, plain paper facsimile machines, or multifunction machines thereof.

[0054] In addition, the paper feed roller of the present invention can also be incorporated into, for example, inkjet printers or automated teller machines (ATMs). The paper feed roller of the present invention rotates while contacting sheets such as paper and plastic films, and conveys the paper by friction. It can be used, for example, as a paper feed roller, a conveyance roller, a platen roller, a paper discharge roller, etc.

Example

[0055] The present invention will be further described based on examples and comparative examples, but the configuration of the present invention is not limited to these examples. 〈Example 1〉 (Preparation of rubber composition) As the rubber, 200 parts by mass of oil-extended EPDM [Esprene 670F manufactured by Sumitomo Chemical Co., Ltd., oil extension amount: 100 phr] (rubber as solid content: 100 parts by mass) was used.

[0056] To 200 parts by mass of such oil-extended EPDM, 12 parts by mass of an alkylphenol resin [Tamanol 510 manufactured by Arakawa Chemical Industries, Ltd., which may be abbreviated as "alkylphenol resin I" hereinafter] and the following respective components were blended and kneaded using a 3L kneader and an open roll.

[0057]

Table 1

[0058] Each component in Table 1 is as follows, and the parts by mass in the table are parts by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content). Filler i: Carbon black HAF [Seast (registered trademark) 3 manufactured by Tokai Carbon Co., Ltd.] Filler ii: Heavy calcium carbonate [BF300 manufactured by Bihoku Powder Chemical Industry Co., Ltd.] Crosslinking aid i: Two types of zinc oxide [manufactured by Mitsui Mining & Smelting Co., Ltd.] Crosslinking aid ii: Stearic acid [Tsubaki manufactured by NOF Corporation] Next, while continuing kneading, the following crosslinking components were blended and further kneaded to prepare a rubber composition for a paper feed member.

[0059]

Table 2

[0060] Each component in Table 2 is as follows, and the parts by mass in the table are parts by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as a solid content). Crosslinking agent: Powdered sulfur [sulfur-based crosslinking agent, manufactured by Tsurumi Chemical Industry Co., Ltd.] Accelerator TOT: Tetrakis(2-ethylhexyl)thiuram disulfide [Nocceler (registered trademark) TOT-N manufactured by Ouchi Shinko Chemical Industry Co., Ltd., thiuram-based accelerator] Accelerator DM: Di-2-benzothiazolyldisulfide [Nocceler DM manufactured by Ouchi Shinko Chemical Industry Co., Ltd., thiazole-based accelerator] (Manufacture of paper feed roller) The above rubber composition for a paper feed member was transfer molded into a cylindrical shape under the conditions of 165 °C for 30 minutes. After grinding to an outer diameter of 21 mm using a cylindrical grinding machine with a shaft 4 having an outer diameter of 12 mm press-fitted into the through hole 3, it was cut to a width of 25 mm to manufacture a paper feed roller 1 having a cylindrical roller body 2 (see Figure 1).

[0061] 〈Example 2〉 A rubber composition for a paper feed member was prepared in the same manner as in Example 1 except that the amount of alkylphenol resin I was 8 parts by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as a solid content), and a paper feed roller 1 was manufactured. 〈Example 3〉 Instead of the alkylphenol resin I, TACKIROL 160 (alkylphenol·acetaldehyde resin, which may be abbreviated as "alkylphenol resin II" hereinafter) manufactured by Taoka Chemical Industry Co., Ltd. was blended in an amount of 4 parts by mass per 200 parts by mass of the oil-extended EPDM (100 parts by mass of rubber as a solid content). A rubber composition for a paper feed member was prepared in the same manner as in Example 1 except for this, and the paper feed roller 1 was manufactured.

[0062] <Comparative Example 1> A rubber composition for a paper feed member was prepared in the same manner as in Example 1 except that the alkylphenol resin I was not blended, and the paper feed roller 1 was manufactured. <Comparative Example 2> A rubber composition for a paper feed member was prepared in the same manner as in Example 1 except that the amount of the alkylphenol resin I was 1 part by mass per 200 parts by mass of the oil-extended EPDM (100 parts by mass of rubber as a solid content), and the paper feed roller 1 was manufactured.

[0063] <Comparative Example 3> The amount of the alkylphenol resin I was 10 parts by mass per 200 parts by mass of the oil-extended EPDM (100 parts by mass of rubber as a solid content). As a crosslinking agent, instead of the sulfur-based crosslinking agent, a peroxide crosslinking agent [dicumyl peroxide, PERKMIL (registered trademark) D manufactured by NOF Corporation] was blended in an amount of 4 parts by mass per 200 parts by mass of the oil-extended EPDM (100 parts by mass of rubber as a solid content). A rubber composition for a paper feed member was prepared in the same manner as in Example 1 except that the accelerator TOT and the accelerator DM were not blended, and the paper feed roller 1 was manufactured.

[0064] In addition, in the crosslinking with the peroxide crosslinking agent, two kinds of crosslinking aids (zinc oxide and stearic acid) are not necessary. However, in Comparative Example 3, the same amounts were blended for the purpose of comparative evaluation with each Example and Comparative Example. <Hardness Test> The rubber compositions prepared in the Examples and Comparative Examples were press-crosslinked under the conditions of 160 °C × 30 minutes to form a sheet having a thickness of 2 mm, and three of them were stacked to form a test piece.

[0065] Then, using this test piece, under the environment of 23°C, in accordance with the measurement method described in Japanese Industrial Standard JIS K6253-3 :2012 "Vulcanized Rubber and Thermoplastic Rubber - Method for Measuring Hardness - Part 3: Durometer Hardness", the value after 3 seconds was read and taken as the Type A durometer hardness 〈Tensile Test〉 The rubber compositions prepared in the examples and comparative examples were press-cured under the conditions of 160°C for 30 minutes to form a sheet with a thickness of 2 mm, which was punched out to prepare a dumbbell-shaped No. 3 test piece specified in Japanese Industrial Standard JIS K6251 :2017 "Vulcanized Rubber and Thermoplastic Rubber - Method for Measuring Tensile Properties", and a tensile test specified in the same standard was carried out under the environment of 23°C to obtain the tensile strength T (MPa) and the elongation at break E b (%).

[0066] 〈Coefficient of Friction Test〉 As shown in Fig. 2, the roller body 2 of the prepared paper feed roller 1 was placed on a paper 7 with a width of 60 mm and a length of 210 mm (P paper (plain paper) manufactured by Fuji Xerox Co., Ltd.) placed on a horizontally installed polytetrafluoroethylene (PTFE) plate 6, and pressed while applying a vertical load W (= 300 gf).

[0067] Next, under the environment of 23°C and a relative humidity of 55%, when the roller body 2 was rotated at 200 rpm in the direction indicated by the arrow R of the dashed line, the conveying force F (gf) applied to the load cell 8 connected to one end of the paper 7 was measured Next, from the measured conveying force F and the vertical load W (= 300 gf), Equation (1): Coefficient of friction μ = F (gf) / W (gf) (1) was used to obtain the coefficient of friction μ

[0068] 〈Abrasion Resistance Test〉 Similar to the coefficient of friction test, as shown in Fig. 2, the roller body 2 of the paper feed roller 1 was placed on a paper 7 with a width of 60 mm and a length of 210 mm (P paper (plain paper) manufactured by Fuji Xerox Co., Ltd.) placed on a horizontally installed PTFE plate 6, and pressed while applying a vertical load W (= 500 gf).

[0069] Next, in an environment with a temperature of 23°C and a relative humidity of 55%, the roller body 2 was continuously rotated at 200 rpm for 10 minutes in the direction indicated by the arrow R of the one-dot chain line. Next, after continuous rotation, the mass (mass after wear) M1 (g) of the roller body 2 was weighed, and from the mass M1 (g) after wear and the initial mass M0 (g) of the roller body 2 weighed before continuous rotation, Equation (2): Mass reduction rate ΔM (%) = (M0 - M1) / M0 × 100 (2) was used to determine the mass reduction rate ΔM.

[0070] The smaller the mass reduction rate ΔM, the more excellent the wear resistance of the roller body 2 can be evaluated. The above results are shown in Table 3.

[0071]

Table 3

[0072] From the results of Examples 1 to 3 and Comparative Examples 1 and 3 in Table 3, by cross-linking the rubber containing oil-extended EPDM with a sulfur-based cross-linking agent, the effect of blending an alkylphenol resin as a tackifier was improved, and the initial coefficient of friction of the roller body of the paper feed roller as a paper feed member was sufficiently increased to a range where paper feed failure does not occur when paper feeding is repeated, and it was found that a decrease in the wear resistance of the roller body can also be suppressed.

[0073] Also, from the results of Examples 1 to 3 and Comparative Example 2, it was found that in order to obtain the above effects, the proportion of the alkylphenol resin needs to be 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the rubber as a solid content in the oil-extended EPDM. Furthermore, from the results of Examples 1 to 3, it was found that various alkylphenol resins that can function as tackifiers can be used as the alkylphenol resin.

[0074] 〈Example 4〉 As the rubber, 100 parts by mass of non-oil-extended EPDM [Esprene 505A manufactured by Sumitomo Chemical Co., Ltd.] was used. To 100 parts by mass of such non-oil-extended EPDM, 5 parts by mass of alkylphenol resin I [Tamanol 510 manufactured by Arakawa Chemical Industries, Ltd. mentioned above] and the following respective components were blended and kneaded using a 3L kneader and an open roll.

[0075]

Table 4

[0076] Each component in Table 4 is the same as in Table 1, and the parts by mass in the table are parts by mass per 100 parts by mass of non-oil-extended EPDM. Next, while continuing the kneading, the following crosslinking components were blended and further kneaded to prepare a rubber composition for a paper feeding member.

[0077]

Table 5

[0078] Each component in Table 2 is the same as in Table 2, and the parts by mass in the table are parts by mass per 100 parts by mass of non-oil-extended EPDM. (Manufacture of paper feed roller) The above rubber composition for a paper feeding member was transfer molded into a cylindrical shape under the conditions of 165 °C × 30 minutes. After grinding the outer diameter to 21 mm using a cylindrical grinding machine with a shaft 4 having an outer diameter of 12 mm press-fitted into the through hole 3, it was cut to a width of 25 mm to manufacture a paper feed roller 1 provided with a cylindrical roller body 2 (see Figure 1).

[0079] 〈Example 5〉 A rubber composition for a paper feeding member was prepared in the same manner as in Example 4 except that alkylphenol resin II [TACKIROL 160, an alkylphenol·acetaldehyde resin manufactured by Takeoka Chemical Industry Co., Ltd. mentioned above] was blended in an amount of 5 parts by mass per 100 parts by mass of non-oil-extended EPDM instead of alkylphenol resin I, and a paper feed roller 1 was manufactured.

[0080] <Comparative Example 4> A rubber composition for a paper feeding member was prepared in the same manner as in Example 4 except that alkylphenol resin I was not compounded, and the paper feed roller 1 was manufactured. <Comparative Example 5> As a crosslinking agent, instead of the sulfur-based crosslinking agent, a peroxide crosslinking agent [the aforementioned dicumyl peroxide, Parkmill D manufactured by NOF Corporation] was compounded at 3 parts by mass per 100 parts by mass of non-oil-extended EPDM. A rubber composition for a paper feeding member was prepared in the same manner as in Example 4 except that accelerator TOT and accelerator DM were not compounded, and the paper feed roller 1 was manufactured.

[0081] In crosslinking with a peroxide crosslinking agent, as described above, two kinds of crosslinking aids (zinc oxide and stearic acid) are not necessary. However, in Comparative Example 5 as well, the same amount is compounded for comparative evaluation with each Example and Comparative Example. Regarding the rubber compositions prepared in the Examples and Comparative Examples, and the manufactured paper feed roller 1, the above-described various tests were carried out to evaluate their properties.

[0082] The results are shown in Table 6.

[0083] [Table 6]

[0084] From the results of Examples 4 and 5 and Comparative Examples 4 and 5 in Table 6, it was found that even in the system using non-oil-extended EPDM, the same results as those of the previous Examples and Comparative Examples using oil-extended EPDM were obtained. That is, from the results of Examples 4 and 5 and Comparative Examples 4 and 5, by crosslinking a rubber containing non-oil-extended EPDM with a sulfur-based crosslinking agent, the effect of compounding an alkylphenol resin as a tackifier was improved, and the initial coefficient of friction of the roller body of the paper feed roller as a paper feeding member was sufficiently increased to a range where paper feeding failure does not occur when paper feeding is repeated. Moreover, it was found that a decrease in the abrasion resistance of the roller body can also be suppressed.

[0085] Also, from the results of Examples 4 and 5, it was found that in order to obtain the above effects, the proportion of the alkylphenol resin needs to be 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the non-oil-extended EPDM. Furthermore, from the results of Examples 4 and 5, it was found that various alkylphenol resins that can function as tackifiers can be used as the alkylphenol resin.

Explanation of Signs

[0086] 1 Paper feed roller 2 Roller body 3 Through hole 4 Shaft 5 Outer peripheral surface 6 Plate 7 Paper 8 Load cell F Conveying force W Vertical load

Claims

1. A rubber composition for a paper feed member, comprising a rubber containing an ethylene-α-olefin copolymer rubber, a crosslinking component for crosslinking the rubber, a tackifier, and a filler, wherein the ethylene-α-olefin copolymer rubber is a copolymer rubber of ethylene, an α-olefin, and a diene, the crosslinking component contains at least a sulfur-based crosslinking agent, the tackifier contains an alkylphenol resin (excluding an alkylphenol resin that functions as a crosslinking agent) in a proportion of 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the total amount of the rubber, and the filler is contained in a proportion of 3 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the total amount of the rubber.

2. The rubber composition for a paper feed member according to claim 1, wherein the ethylene-α-olefin copolymer rubber is an ethylene-propylene-diene copolymer rubber.

3. The rubber composition for a paper feed member according to claim 1 or 2, wherein the sulfur-based crosslinking agent uses 0.5 parts by mass or more and 2 parts by mass or less of sulfur per 100 parts by mass of the total amount of the rubber.

4. A paper feed roller including a roller body made of a crosslinked product of the rubber composition for a paper feed member according to any one of claims 1 to 3.

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