Rubber composition for sheet conveying roller and sheet conveying roller

Abstract

To provide a rubber composition which has friction coefficient that can be used for sheet conveying rollers, and can make sheet conveying rollers with excellent ozone resistance and tensile strength.SOLUTION: A rubber composition for a sheet conveying roller 1 contains isoprene-based rubber and ethylene-vinyl acetate copolymer as base rubber, and the content of the isoprene-based rubber in the base rubber is 50 mass% or more and less than 65 mass%, and vinyl acetate content of the ethylene-vinyl acetate copolymer is 20 mass% to 60 mass%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to rubber compositions used to form sheet-conveying rollers. [Background technology]

[0002] Various types of sheet transport rollers are incorporated into the sheet transport mechanisms of devices such as electrostatic copiers, laser printers, plain paper facsimiles, and all-in-one machines thereof, as well as image forming devices such as inkjet printers, and automated teller machines (ATMs).The sheet transport rollers rotate while in contact with sheets such as paper and plastic film, transporting the sheets by friction.

[0003] Ethylene propylene diene monomer copolymer (EPDM) is often used as a material for sheet conveying rollers due to its cost and ozone resistance. However, rollers made from EPDM have a low coefficient of friction due to the influence of components such as fillers contained in paper (also known as paper dust), making them prone to conveyance problems. Therefore, for example, Patent Document 1 proposes making rollers from a rubber composition containing EPDM and isoprene rubber (IR) (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-5638 Summary of the Invention [Problem to be solved by the invention]

[0005] Sheet conveying rollers are generally assembled by inserting a roller shaft into a through-hole in a cylindrically shaped rubber roller body. The inner diameter of the rubber roller body is designed to be smaller than the outer diameter of the roller shaft, and the rubber roller body is fixed to the roller shaft by the clamping force of the rubber.

[0006] Here, rollers made from a rubber composition containing EPDM and IR have a high coefficient of friction but very low tensile strength, and therefore, when a roller shaft is press-fitted into a rubber roller body, the rubber roller breaks within a few days after the roller shaft is press-fitted. The present disclosure has been made in view of the above circumstances, and aims to provide a rubber composition that has a friction coefficient suitable for use as a sheet conveying roller and that can be used to produce a sheet conveying roller that is excellent in ozone resistance and tensile strength. [Means for solving the problem]

[0007] The rubber composition for a sheet conveying roller of the present disclosure, which has been able to solve the above-mentioned problems, contains an isoprene-based rubber and an ethylene-vinyl acetate copolymer as a base rubber, and is characterized in that the content of the isoprene-based rubber in the base rubber is 50% by mass or more and less than 65% by mass, and the vinyl acetate content of the ethylene-vinyl acetate copolymer is 20% by mass to 60% by mass. When the rubber composition contains a predetermined amount of isoprene-based rubber and a specific ethylene-vinyl acetate copolymer, the ozone resistance and tensile strength of the cured product can be increased while maintaining the coefficient of friction. [Effects of the Invention]

[0008] By using the rubber composition for a sheet transport roller of the present disclosure, it is possible to produce a sheet transport roller that has a friction coefficient suitable for use as a sheet transport roller and is excellent in ozone resistance and tensile strength. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view illustrating an example of a sheet conveying roller according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram illustrating a method for measuring a friction coefficient. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Rubber composition for sheet conveying roller> The rubber composition for a sheet conveying roller (hereinafter sometimes simply referred to as "rubber composition") contains, as base rubber, an isoprene-based rubber and an ethylene-vinyl acetate copolymer.

[0011] (Isoprene rubber) The isoprene-based rubber is preferably at least one selected from the group consisting of natural rubber (NR), modified NR, modified NR, isoprene rubber (IR), and modified IR. One type of isoprene-based rubber may be used alone, or two or more types may be used in combination. Examples of the natural rubber include CV-50, CV-60, RSS#3, and TSR20. Examples of the modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber. Examples of the modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of the isoprene rubber include IR2200. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber.

[0012] The content of isoprene-based rubber in the base rubber is 50% by mass or more, preferably 52% by mass or more, more preferably 55% by mass or more, and less than 65% by mass, preferably 64% by mass or less, more preferably 63% by mass or less. If the content of isoprene-based rubber is 50% by mass or more, the hardness of the formed roller will not be too high and the coefficient of friction will be good, and if it is less than 65% by mass, the ozone resistance of the roller will be further improved.

[0013] (ethylene-vinyl acetate copolymer) The rubber composition contains an ethylene-vinyl acetate copolymer having a vinyl acetate content of 20% by mass to 60% by mass. By containing the specific ethylene-vinyl acetate copolymer, the tensile strength of the obtained roller can be increased, and the roller can be prevented from breaking.

[0014] The ethylene-vinyl acetate copolymer is a copolymer of ethylene and vinyl acetate. The ethylene-vinyl acetate copolymer may be used alone or in combination of two or more.

[0015] The vinyl acetate content of the ethylene-vinyl acetate copolymer is 20% by mass or more, preferably 22% by mass or more, more preferably 25% by mass or more, and 60% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less. If the vinyl acetate content is 20% by mass or more, the hardness of the roller formed will not be too high and the coefficient of friction will be good, and if it is 60% by mass or less, the ozone resistance of the roller will be further improved.

[0016] The melt flow rate (190°C, load 2.16 kgf) of the ethylene-vinyl acetate copolymer is not particularly limited, but is preferably 1000 g / 10 min or less, more preferably 700 g / 10 min or less, even more preferably 400 g / 10 min or less, and is preferably 0.1 g / 10 min or more, more preferably 0.2 g / 10 min or more, even more preferably 0.5 g / 10 min or more. If the melt flow rate of the ethylene-vinyl acetate copolymer is 1000 g / 10 min or less, the tensile strength is further improved, and if it is 0.1 g / 10 min or less, the kneading and molding processability are improved.

[0017] The content of the ethylene-vinyl acetate copolymer in the base rubber is preferably 35% by mass or more, more preferably 36% by mass or more, and even more preferably 37% by mass or more, and is preferably 50% by mass or less, more preferably 48% by mass or less, and even more preferably 45% by mass or less. If the content of the ethylene-vinyl acetate copolymer is 35% by mass or more, improved ozone resistance can be expected, and if it is 50% by mass or less, an improved coefficient of friction can be expected.

[0018] The mass ratio of the isoprene rubber to the ethylene-vinyl acetate copolymer in the base rubber (isoprene rubber / ethylene-vinyl acetate copolymer) is preferably 1.00 or more, more preferably 1.08 or more, even more preferably 1.22 or more, and is preferably 1.86 or less, more preferably 1.78 or less, even more preferably 1.71 or less. If the mass ratio is 1.00 or more, an improved coefficient of friction can be expected, and if it is 1.86 or less, ozone resistance will be improved.

[0019] The base rubber preferably contains only an isoprene-based rubber and an ethylene-vinyl acetate copolymer. The base rubber may contain other rubber components to the extent that the effects of the present disclosure are not impaired. In this case, the total content of the isoprene-based rubber and the ethylene-vinyl acetate copolymer in the base rubber is preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0020] Examples of the other rubber components include epichlorohydrin rubber, ethylene-propylene-diene copolymer (EPDM), ethylene-propylene copolymer (EPM), ethylene-butene copolymer (EBR), ethylene-octene copolymer (EOR), ethylene-propylene-butene copolymer (EPBR), ethylene-butene-diene copolymer (EBDM), ethylene-propylene-butene-diene copolymer (EPBDM), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), chloroprene rubber (CR), acrylic rubber, butyl rubber, silicone rubber, etc. These other rubber components may be used alone or in combination of two or more.

[0021] (Crosslinking agent) The rubber composition may use a sulfur-based crosslinking agent or an organic peroxide as a crosslinking agent. Examples of the sulfur-based crosslinking agent include elemental sulfur and sulfur donor compounds. Examples of the elemental sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur. Examples of the sulfur donor compounds include 4,4'-dithiobismorpholine.

[0022] Examples of the organic peroxide include dicumyl peroxide, α,α'-bis(t-butylperoxy-m-diisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane. The crosslinking agents may be used alone or in combination of two or more. The crosslinking agent is preferably an organic peroxide. The use of an organic peroxide allows for crosslinking of the ethylene-vinyl acetate copolymer.

[0023] The content of the crosslinking agent is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1.0 part by mass or more, per 100 parts by mass of the base rubber, and is preferably 3.0 parts by mass or less, more preferably 2.7 parts by mass or less, and even more preferably 2.5 parts by mass or less. If the content of the crosslinking agent is 0.5 parts by mass or more, the wear resistance of the formed roller is further improved, and if it is 3.0 parts by mass or less, the hardness of the formed roller does not become too high, and the friction coefficient is good.

[0024] (Other ingredients) The rubber composition may contain compounding agents that are commonly used as compounding agents for rubber, such as fillers, processing aids, antioxidants, hindering agents, and pigments, as long as they do not detract from the spirit of the present disclosure.

[0025] The filler may be any of those commonly used as compounding agents for rubber, such as carbon black, silica, calcium carbonate, talc, clay, magnesium carbonate, aluminum oxide, etc. By compounding a filler, the mechanical strength, etc. of the resulting roller can be improved.

[0026] The amount of the filler, per 100 parts by mass of the base rubber, is preferably at least 3 parts by mass, more preferably at least 5 parts by mass, and even more preferably at least 10 parts by mass; it is preferably at most 100 parts by mass, more preferably at most 70 parts by mass, and even more preferably at most 50 parts by mass.

[0027] When carbon black is used as the filler, the amount of carbon black is preferably 3 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the base rubber. By reducing the amount of carbon black used, it is possible to prevent the sheet from becoming soiled during transport.

[0028] Examples of the processing aid include fatty acids having 12 to 30 carbon atoms (such as stearic acid), fatty acid esters, fatty acid metal salts, fatty acid amides, and hydrocarbons (paraffins).

[0029] Examples of the antioxidant include nickel diethyldithiocarbamate and nickel dibutyldithiocarbamate.

[0030] The rubber composition for a sheet conveying roller can be prepared by blending a base rubber and, if necessary, other raw materials, and kneading them using a pressure kneader, a Banbury mixer, an open roll, etc. The kneading method and conditions are appropriately selected depending on the production scale.

[0031] The hardness (Durometer type A hardness) of the cured product of the rubber composition is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more, and is preferably 90 or less, more preferably 85 or less, and even more preferably 80 or less. If the hardness of the cured product is 10 or more, the hardness becomes suitable for sheet conveyance, and the conveying force is further improved, and if the hardness is 90 or less, it is easier to press-fit the roller shaft.

[0032] The tensile strength of the cured product of the rubber composition is preferably 2 MPa or more, more preferably 2.5 MPa or more, and even more preferably 3 MPa or more. If the tensile strength of the cured product is 2 MPa or more, breakage of the roller when the shaft is pressed into it is further suppressed. Furthermore, if the tensile strength is 3 MPa or more, breakage of the roller is further suppressed. The upper limit of the tensile strength of the cured product is not particularly limited, but is usually about 30 MPa.

[0033] The breaking elongation of the cured product of the rubber composition is preferably 100% or more, more preferably 200% or more, and even more preferably 300% or more. If the breaking elongation of the cured product is 100% or more, the roller is more likely to be prevented from breaking when the shaft is pressed into it. The upper limit of the breaking elongation of the cured product is not particularly limited, but is usually about 1000%.

[0034] <Sheet transport roller> The sheet conveying roller of the present disclosure is obtained by curing the rubber composition for a sheet conveying roller. The shape of the sheet transport roller may be cylindrical, columnar, polygonal tubular, or polygonal pillar. When the sheet transport roller is cylindrical or polygonal tubular, the paper feed roller preferably has a shaft. The material of the shaft is not particularly limited, and examples include metal, ceramic, and resin.

[0035] An example of a sheet conveying roller is shown in Figure 1. The sheet conveying roller 1 shown in Figure 1 includes a roller body 2 formed by molding the rubber composition of the present disclosure into a cylindrical shape and cross-linking it. A through-hole 3 with a circular cross section is provided in the center of the roller body 2, and a cylindrical shaft 4 that is connected to a drive system (not shown) is inserted into and fixed to the through-hole 3. The outer circumferential surface of the roller body 2 is formed into a cylindrical shape concentric with the through-hole 3 and the shaft 4.

[0036] 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, whose outer diameter is larger than the inner diameter of the through-hole 3, into the through-hole 3 of the roller body 2. In other words, a certain idling torque (the limit torque at which idling does not occur) is ensured between the two by the interference based on the diameter difference between the two.

[0037] The shaft 4 is made of, for example, metal, ceramic, hard resin, etc. A plurality of roller bodies 2 may be fixed to a single shaft 4 at a plurality of locations, as required. Methods for manufacturing the roller body 2 include a method in which a rubber composition is molded into a cylindrical shape by extrusion molding or the like, and then crosslinked by press crosslinking or the like; a method in which a rubber composition is molded into a cylindrical shape by transfer molding or the like, and simultaneously crosslinked;

[0038] At any point during the manufacturing process, the outer circumferential surface of the roller body 2 may be polished to a predetermined surface roughness, knurled, textured, or the like, as needed. Also, both ends of the roller body 2 may be cut so that the outer circumferential surface has a predetermined width. The outer circumferential surface of the roller body 2 may be covered with an optional coating layer.

[0039] The roller body 2 may also be formed in a two-layer structure, with an outer layer on the outer peripheral surface side and an inner layer on the through-hole 3 side. In this case, it is preferable that at least the outer layer is formed from the rubber composition of the present disclosure. However, in consideration of simplifying the structure, improving productivity, and reducing manufacturing costs, it is preferable that the roller body 2 have a single-layer structure as shown in FIG. 1.

[0040] The roller body 2 may also have a porous structure. However, in order to improve abrasion resistance and reduce compression set, making it less likely to develop dents due to deformation even if contact at one point continues for a relatively long period of time, it is preferable that the roller body 2 has a substantially non-porous structure.

[0041] Depending on the application of the sheet conveying roller 1, the through hole 3 may be provided at a position eccentric to the center of the roller body 2. Furthermore, the outer circumferential surface of the roller body 2 may not be cylindrical but may have an irregular shape, for example, a cylindrical outer circumferential surface with a partially cut-out shape. To manufacture a sheet conveying roller 1 having a roller body 2 with such an irregular shape, the roller body 2 may be directly molded into an irregular shape by the manufacturing method described above and then crosslinked, or the roller body 2 molded into a cylindrical shape may be post-processed to have the irregular shape.

[0042] In addition, a through hole 3 of the roller body 2 formed in a cylindrical shape is provided with a hole corresponding to the irregular shape of the roller body 2. The shaft 4 having a deformed shape may be press-fitted to deform the roller body 2 into an irregular shape. In this case, polishing, knurling, or embossing of the outer peripheral surface 5 is performed on the cylindrical outer peripheral surface before deformation. 5, improving workability.

[0043] <Image forming device> The sheet conveying roller of the present disclosure can be incorporated into various image forming apparatuses that use electrophotography, such as laser printers, electrostatic copiers, plain paper facsimile machines, or combination machines of these. The sheet conveying roller of the present disclosure can also be incorporated into inkjet printers, ATMs, etc.

[0044] The sheet conveying roller of the present disclosure rotates while in contact with a sheet, conveying the sheet by friction. The sheet may be a single sheet such as a sheet of paper or a continuous sheet such as continuous paper. The sheet conveying roller can be used as, for example, a paper feed roller, a conveying roller, a platen roller, a paper discharge roller, etc.

[0045] The sheet conveying roller of the present disclosure has a good coefficient of friction of the roller body, which allows it to exhibit good paper passing performance. In addition, the sheet conveying roller of the present disclosure has excellent ozone resistance and tensile strength of the roller body, which prevents the roller body from cracking or breaking during use. [Example]

[0046] The present disclosure will be described in detail below using examples, but the present disclosure is not limited to the following examples, and all modifications and embodiments that do not deviate from the spirit of the present disclosure are included within the scope of the present disclosure.

[0047] [Evaluation method] (1)Hardness The hardness of the cured rubber composition was measured in accordance with JIS K6253-3 (2012). Specifically, the rubber composition was pressed at 170°C for 20 minutes to produce a 2 mm thick sheet. Three of these sheets were stacked together to avoid the influence of the measurement substrate, and the pressure plate of a Type A durometer was brought into contact with the sheet. The value was read 3 seconds after the contact.

[0048] (2) Tensile strength and elongation at break The tensile strength and elongation at break (elongation at break) of the cured rubber composition were measured in accordance with JIS K6251 (2017). Specifically, the rubber composition was pressed at 170°C for 20 minutes to produce a 2 mm thick sheet, which was then punched into a dumbbell-shaped test specimen (dumbbell No. 3, parallel portion thickness 2 mm, initial gauge length 20 mm). Physical properties were measured using a tensile test measuring device (measurement temperature 23°C, tensile speed 500 mm / min). The tensile strength was calculated by dividing the maximum tensile force recorded when the test specimen was pulled until it broke by the cross-sectional area of ​​the test specimen before the test.

[0049] (3) Ozone test The cured rubber composition was subjected to an ozone degradation test in accordance with JIS K6259-1 (2015) Method A. Specifically, the rubber composition was pressed at 170°C for 20 minutes to produce a 2 mm thick sheet, which was then cut into 10 mm wide, 100 mm long strips to prepare test specimens. The test specimens were attached to a stretching jig and stretched longitudinally to adjust the tensile strain to 20%. The test specimens with this tensile strain were exposed to an environment of 40°C and an ozone concentration of 50 pphm for 72 hours, and ozone cracking after exposure was observed. Those in which no ozone cracks were observed were evaluated as good (◯), and those in which cracks were observed were evaluated as poor (×).

[0050] (4) Roller evaluation As shown in Figure 2, plain paper 11 (P paper, manufactured by Fujifilm Business Innovation) was placed on a horizontally placed polytetrafluoroethylene (PTFE) plate 10. The roller body 2 of the sheet transport roller 1 was placed on this paper 11, and a vertical load W1 (= 300 gf) was applied to the shaft 4 to press it against the plate 10. Next, in an environment of 23°C temperature and 55% relative humidity, the roller body 2 was rotated at 200 rpm in the direction indicated by the dashed arrow R1, and the conveying force F (gf) applied to the load cell 12 connected to one end of the paper 11 was measured. The initial coefficient of friction μ was calculated from the measured conveying force F and the vertical load W1 (=300 gf) using formula (1). μ=F(gf) / W1(gf) (1)

[0051] [Preparation of Rubber Composition] A rubber composition was prepared by mixing the raw materials using a kneader and an open roll so as to obtain the formulation shown in Table 1. Table 1 shows the measurement results of the cured product of the obtained rubber composition.

[0052] [Table 1]

[0053] The raw materials used in Table 1 are as follows: IR: Nipol (registered trademark) IR2200 (isoprene rubber) manufactured by Nippon Zeon NR: Made in Vietnam, natural rubber (CV-60) EVA1: Tosoh's "Ultrathene (registered trademark) 680" (ethylene-vinyl acetate copolymer (vinyl acetate content 20% by mass, melt flow rate (190°C, load 2.16 kgf) 160 g / 10 min)) EVA2: Tosoh's "Ultrathene 750" (ethylene-vinyl acetate copolymer (vinyl acetate content 32% by mass, melt flow rate (190°C, load 2.16 kgf) 30 g / 10 min)) EVA3: ARLANXEO's "Levapren® 400" (ethylene-vinyl acetate copolymer (vinyl acetate content 40% by mass)) EVA4: ARLANXEO's "Levapren 600" (ethylene-vinyl acetate copolymer (vinyl acetate content 60% by mass)) EVA5: ARLANXEO's "Levapren 800" (ethylene-vinyl acetate copolymer (vinyl acetate content 80% by mass) EPDM: Sumitomo Chemical's "ESPRENE (registered trademark) 505A" (ethylene propylene diene monomer copolymer) Carbon black: "Seast (registered trademark) 3" manufactured by Tokai Carbon Calcium carbonate: Bihoku Powder Industry Co., Ltd., "BF-300" Organic peroxide: NOF Corp., "Percumyl (registered trademark) D" (dicumyl peroxide)

[0054] [Manufacturing of sheet transport rollers] The rubber composition obtained above was transferred to a cylindrical shape at 170°C for 30 minutes. A shaft (outer diameter 12 mm) was pressed into the cylindrical molded body, and the rubber roller was ground using a cylindrical grinder to an outer diameter of 20 mm. The rubber roller portion was then cut to a width of 23 mm to produce a sheet conveying roller. The evaluation results of the obtained sheet conveying roller are shown in Table 1.

[0055] Rubber compositions Nos. 1 to 4 contain an isoprene-based rubber and an ethylene-vinyl acetate copolymer as a base rubber, the content of the isoprene-based rubber in the base rubber being 50% by mass or more and less than 65% by mass, and the vinyl acetate content of the ethylene-vinyl acetate copolymer being 20% ​​by mass to 60% by mass.

[0056] The cured products obtained from these rubber compositions Nos. 1 to 4 had high tensile strength and excellent ozone resistance. Therefore, the sheet conveying rollers made using these rubber compositions Nos. 1 to 4 were less likely to break after the roller shaft was pressed into them, and were also less susceptible to ozone cracking during use. Furthermore, all of the sheet conveying rollers made using these rubber compositions Nos. 1 to 4 had a high coefficient of friction and were also equipped with sheet conveying performance.

[0057] Rubber composition No. 5 contains an isoprene-based rubber and an ethylene-propylene-diene monomer copolymer as the base rubber, but does not contain an ethylene-vinyl acetate copolymer. This rubber composition No. 5 had a low tensile strength of 2.9 MPa. Therefore, a sheet conveying roller made using this rubber composition No. 5 may break shortly after the roller shaft is pressed into it.

[0058] Rubber composition No. 6 contains an isoprene-based rubber and an ethylene-vinyl acetate copolymer as the base rubber, and the content of the isoprene-based rubber in the base rubber is less than 50 mass %. Because the amount of isoprene-based rubber in this rubber composition No. 6 is too small, the friction coefficient of the resulting sheet conveying roller was as low as 1.38, and the sheet conveying performance was insufficient.

[0059] Rubber composition No. 7 contains an isoprene-based rubber and an ethylene-vinyl acetate copolymer as the base rubber, and the content of the isoprene-based rubber in the base rubber is 65 mass% or more. Because the amount of isoprene-based rubber in this rubber composition No. 7 is too high, the ozone resistance of the cured product was poor.

[0060] Rubber composition No. 8 contains an isoprene-based rubber and an ethylene-vinyl acetate copolymer as the base rubber, and the ethylene-vinyl acetate copolymer has a vinyl acetate content of more than 60% by mass. Although rubber composition No. 8 contains an ethylene-vinyl acetate copolymer, the ethylene-vinyl acetate copolymer has a vinyl acetate content of more than 60% by mass, so the ozone resistance of the cured product was poor.

[0061] The present disclosure (1) is a rubber composition for a sheet conveying roller, which comprises an isoprene-based rubber and an ethylene-vinyl acetate copolymer as a base rubber, the content of the isoprene-based rubber in the base rubber being 50% by mass or more and less than 65% by mass, and the vinyl acetate content of the ethylene-vinyl acetate copolymer being 20% ​​by mass to 60% by mass.

[0062] The present disclosure (2) is the rubber composition for a sheet-conveying roller according to the present disclosure (1), which contains an organic peroxide.

[0063] The present disclosure (3) is a rubber composition for a sheet conveying roller according to the present disclosure (1) or (2), in which the content of ethylene-vinyl acetate copolymer in the base rubber is 35% by mass or more and 50% by mass or less.

[0064] The present disclosure (4) is a rubber composition for a sheet conveying roller according to the present disclosure (2) or (3), wherein the content of the organic peroxide in the rubber composition is 0.5 parts by mass to 3 parts by mass per 100 parts by mass of the base rubber.

[0065] The present disclosure (5) is a sheet conveying roller obtained by curing the rubber composition for a sheet conveying roller according to any one of the present disclosures (1) to (4). [Explanation of symbols]

[0066] 1: Sheet conveying roller, 2: Roller body, 3: Through hole, 4: Shaft, 10: Plate, 11: Paper, 12: Load cell

Claims

1. The base rubber contains an isoprene-based rubber and an ethylene-vinyl acetate copolymer, the content of isoprene-based rubber in the base rubber is 50% by mass or more and less than 65% by mass, the base rubber has an ethylene-vinyl acetate copolymer content of 35% by mass or more and 50% by mass or less, the combined content of the isoprene-based rubber and the ethylene-vinyl acetate copolymer in the base rubber is 95% by mass or more, The rubber composition for a sheet conveying roller is characterized in that the ethylene-vinyl acetate copolymer has a vinyl acetate content of 20% by mass to 60% by mass.

2. The rubber composition for a sheet-conveying roller according to claim 1, further comprising an organic peroxide.

3. A rubber composition for a sheet conveying roller as described in claim 1 or 2, wherein the mass ratio of isoprene-based rubber to ethylene-vinyl acetate copolymer in the base rubber (isoprene-based rubber / ethylene-vinyl acetate copolymer) is 1.00 or more and 1.86 or less.

4. 4. The rubber composition for a sheet-conveying roller according to claim 2, wherein the content of the organic peroxide in the rubber composition is 0.5 to 3 parts by mass per 100 parts by mass of the base rubber.

5. A sheet conveying roller obtained by curing the rubber composition for a sheet conveying roller according to any one of claims 1 to 4.

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