Rubber composition for paper feed roller and paper feed roller

Abstract

To provide a paper feeding roller capable of suppressing a deterioration in frictional coefficient even when paper containing a large amount of silicate components such as silica and talc is repeatedly conveyed.SOLUTION: A rubber composition for a paper feed roller contains (A) a base rubber and (B) a vulcanizing agent. The (A) base rubber contains an epichlorohydrin-ethylene oxide copolymer and / or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer, and the (B) vulcanizing agent contains a thiourea compound and / or a triazine compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to rubber compositions used in forming paper feed rollers. [Background technology]

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

[0003] The paper feed roller is often made of ethylene-propylene-diene rubber (EPDM). However, when a roller made of EPDM repeatedly conveys paper with a high ash content, the friction coefficient of the paper feed roller decreases, which can lead to problems such as non-feeding. For this reason, a technology has been proposed, such as in Patent Document 1, in which isoprene rubber (IR) is blended with EPDM to suppress the decrease in the friction coefficient of the roller.

[0004] It has also been proposed to use epichlorohydrin-based rubber as a material for paper feed rollers. For example, Patent Document 2 describes a paper feed belt containing epichlorohydrin rubber and a sulfur-based vulcanizing agent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-34428 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-100165 Summary of the Invention [Problem to be solved by the invention]

[0006] Regarding the paper feed roller, when paper containing silica or silicate components is repeatedly conveyed, the friction coefficient of the paper feed roller decreases, causing a problem of poor conveyance. The present disclosure has been made in consideration of the above circumstances, and aims to provide a paper feed roller that can suppress a decrease in the friction coefficient even when repeatedly transporting paper that contains a large amount of silicate components such as silica and talc. [Means for solving the problem]

[0007] The rubber composition for a paper feed roller of the present disclosure, which has been able to solve the above-mentioned problems, contains (A) a base rubber and (B) a vulcanizing agent, wherein the (A) base rubber contains an epichlorohydrin-ethylene oxide copolymer and / or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer, and the (B) vulcanizing agent contains a thiourea compound and / or a triazine compound.

[0008] The rubber composition contains (A) a specific hydrin-based rubber as the base rubber and (B) a thiourea compound and / or a triazine compound as a vulcanizing agent, and the resulting paper feed roller prevents a decrease in the friction coefficient even when repeatedly conveying paper containing a large amount of silicate components. Although some hydrin-based rubbers can be crosslinked by sulfur or peroxide, the use of these crosslinking agents makes it difficult to obtain the desired roller characteristics. [Effects of the Invention]

[0009] By using the rubber composition for a paper feed roller of the present disclosure, it is possible to produce a paper feed roller that can suppress a decrease in the coefficient of friction even when repeatedly conveying paper that contains a large amount of silicate components such as silica and talc. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view illustrating an example of a conductive rubber roller according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram illustrating a method for measuring a friction coefficient. [Figure 3]FIG. 10 is a schematic diagram illustrating a repeated paper-passing simulation test. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Rubber composition for paper feed roller> The rubber composition for a paper-feed roller contains (A) a base rubber and (B) a vulcanizing agent.

[0012] (A) Base rubber The base rubber (A) contains an epichlorohydrin-ethylene oxide copolymer and / or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer. One type of base rubber (A) may be used alone, or two or more types may be used in combination.

[0013] The ethylene oxide content of the epichlorohydrin-ethylene oxide copolymer and / or epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer is preferably 50 mol% or more, more preferably 55 mol% or more, and even more preferably 60 mol% or more. An ethylene oxide content of 50 mol% or more further suppresses the decrease in the coefficient of friction when paper containing large amounts of silica or talc is conveyed. When the (A) base rubber contains two or more types of epichlorohydrin-ethylene oxide copolymer and / or epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer, the average content of the ethylene oxide component in these copolymers is calculated.

[0014] The (A) base rubber is preferably composed solely of an epichlorohydrin-ethylene oxide copolymer and / or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer. The (A) base rubber may contain rubber components other than the epichlorohydrin-ethylene oxide copolymer and the epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer. In this case, the total content of the epichlorohydrin-ethylene oxide copolymer and / or the epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer in the (A) base rubber is preferably 50% by mass or more, or 85% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0015] Examples of the other rubber components include epichlorohydrin homopolymer, epichlorohydrin-allyl glycidyl ether copolymer, epichlorohydrin-propylene oxide copolymer, epichlorohydrin-propylene oxide-allyl glycidyl ether copolymer, 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.

[0016] (B) Vulcanizing agent The (B) vulcanizing agent contains a thiourea compound and / or a triazine compound. The (B) vulcanizing agent may be used alone or in combination of two or more. The rubber composition for a paper-feed roller preferably contains only a thiourea compound or only a triazine compound as the (B) vulcanizing agent.

[0017] The amount of the thiourea compound and / or triazine compound is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and even more preferably 0.5 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the (A) base rubber. If the amount is 0.1 part by mass or more, the base rubber is sufficiently crosslinked, and the physical properties of the molded product are improved, while if the amount is 10 parts by mass or less, the paper feed roller does not become too hard, and a decrease in the friction coefficient with use is further suppressed.

[0018] The thiourea compound is preferably a compound represented by formula (1).

[0019] [ka] [In formula (1), R 1 ~R 4 R each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. 2 and R 3 may be bonded to each other.]

[0020] R 1 ~R 4 The alkyl group having 1 to 12 carbon atoms, represented by the formula (I), may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 8, and even more preferably 1 to 4. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group.

[0021] R 1 ~R 4 Examples of the aryl group represented by the formula (I) include a phenyl group and a naphthyl group.

[0022] Examples of the thiourea compound include ethylene thiourea, trimethyl thiourea, N,N'-diethyl thiourea, tributyl thiourea, dibutyl thiourea, dilauryl thiourea, N,N'-diphenyl thiourea, etc. Among these, ethylene thiourea is preferred.

[0023] The triazine compound is preferably a triazine thiol compound having a triazine ring structure and a thiol group directly bonded to the triazine ring.

[0024] The triazine thiol compound is preferably a compound represented by formula (2).

[0025] [ka] [In formula (2), X 1 and X 2 are each independently a thiol group, -NR 11 R 12 represents a group, where R 11 and R 12 each independently represents an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 10 carbon atoms.]

[0026] R 11 and R 12 The alkyl group having 1 to 12 carbon atoms, represented by the formula (I), may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 8, and even more preferably 1 to 4. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group.

[0027] R 11 and R 12 Examples of the aryl group represented by the formula (I) include a phenyl group and a naphthyl group.

[0028] Examples of triazine thiol compounds include 2,4,6-trimercapto-1,3,5-triazine, 6-anilino-1,3,5-triazine-2,4-dithiol, 6-methylamino-1,3,5-triazine-2,4-dithiol, 6-dimethylamino-1,3,5-triazine-2,4-dithiol, 6-ethylamino-1,3,5-triazine-2,4-dithiol, 6-diethylamino-1,3,5-triazine-2,4-dithiol, and 6-propylamino-1,3,5- Examples include triazine-2,4-dithiol, 6-dipropylamino-1,3,5-triazine-2,4-dithiol, 6-butylamino-1,3,5-triazine-2,4-dithiol, 6-dibutylamino-1,3,5-triazine-2,4-dithiol, 6-hexylamino-1,3,5-triazine-2,4-dithiol, 6-octylamino-1,3,5-triazine-2,4-dithiol, and 6-decylamino-1,3,5-triazine-2,4-dithiol. Among these, 2,4,6-trimercapto-1,3,5-triazine is preferred.

[0029] Acid acceptor The rubber composition for a paper feed roller preferably contains an acid acceptor because epichlorohydrin rubber may generate chlorine during vulcanization. A commonly used acid acceptor can be used as the acid acceptor. The acid acceptor is preferably at least one selected from the group consisting of hydrotalcite, magnesium oxide, calcium oxide, calcium hydroxide, and magnesium hydroxide.

[0030] The amount of the acid acceptor is preferably at least 1 part by mass, more preferably at least 2 parts by mass, and even more preferably at least 3 parts by mass, per 100 parts by mass of the (A) base rubber, and is preferably at most 10 parts by mass, more preferably at most 7 parts by mass, and even more preferably at most 5 parts by mass.

[0031] Other ingredients The rubber composition for the paper feed roller may contain compounding agents that are commonly used as compounding agents for rubber, such as fillers, vulcanization accelerators, vulcanization retarders, processing aids, antioxidants, and pigments, within the scope of the present disclosure.

[0032] Filler Examples of the filler include carbon black, calcium carbonate, silica, clay, talc, magnesium carbonate, aluminum hydroxide, etc. By blending a filler, the mechanical strength, etc. of the resulting paper feed roller can be improved.

[0033] The content of the filler 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, per 100 parts by mass of the (A) base rubber, and 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.

[0034] When carbon black is used as the filler, the amount of carbon black is preferably not more than 1.0 part by weight, more preferably not more than 0.8 part by weight, and even more preferably not more than 0.5 part by weight, per 100 parts by weight of the (A) base rubber.

[0035] Vulcanization accelerator The vulcanization accelerator may be either an inorganic accelerator or an organic accelerator. Examples of the inorganic accelerator include slaked lime, magnesia (MgO), and litharge (PbO). Examples of the organic accelerator include guanidine accelerators, thiazole accelerators, thiuram accelerators, sulfenamide accelerators, and dithiocarbamate accelerators. The vulcanization accelerators may be used alone or in combination of two or more.

[0036] Examples of the guanidine accelerator include 1,3-diphenylguanidine and 1,3-di-o-tolylguanidine.

[0037] Examples of the thiazole accelerator include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(N,N-diethylthiocarbamoylthio)benzothiazole, and 2-(4'-morpholinodithio)benzothiazole.

[0038] Examples of the thiuram accelerator include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, and dipentamethylenethiuram tetrasulfide.

[0039] Examples of the sulfenamide accelerator include N-cyclohexyl-2-benzothiazolylsulfenamide and N-oxydiethylene-2-benzothiazolylsulfenamide.

[0040] The content of the vulcanization accelerator is preferably at least 0.1 part by mass, more preferably at least 0.2 part by mass, and even more preferably at least 0.3 part by mass, per 100 parts by mass of the (A) base rubber, and is preferably at most 5 parts by mass, more preferably at most 4 parts by mass, and even more preferably at most 3 parts by mass.

[0041] When the (B) vulcanizing agent contains a triazine compound, the vulcanization accelerator preferably contains the guanidine accelerator. In this case, the mass ratio of the amount of the triazine compound to the amount of the guanidine accelerator (triazine compound / guanidine accelerator) is preferably 0.5 or more, more preferably 1 or more, and is preferably 10 or less, more preferably 5 or less.

[0042] The vulcanization retarder may be appropriately selected depending on the vulcanizing agent (B) used. Examples of the vulcanization retarder include N-cyclohexylthiophthalimide, N-nitrosodiphenylamine, phthalic anhydride, and 4,4'-dithiodimorpholine.

[0043] The content of the vulcanization retarder is preferably at least 0.05 parts by mass, more preferably at least 0.1 parts by mass, and even more preferably at least 0.2 parts by mass, per 100 parts by mass of the (A) base rubber, and is preferably at most 5 parts by mass, more preferably at most 3 parts by mass, and even more preferably at most 2 parts by mass.

[0044] When the (B) vulcanizing agent contains a thiourea compound, the vulcanization retarder preferably contains 4,4'-dithiodimorpholine. In this case, the mass ratio of the amount of the thiourea compound to the amount of the 4,4'-dithiodimorpholine (thiourea compound / 4,4'-dithiodimorpholine) is preferably 0.5 or more, more preferably 1 or more, and is preferably 10 or less, more preferably 5 or less.

[0045] When the (B) vulcanizing agent contains a triazine compound, it is preferable to contain N-cyclohexylthiophthalimide as a vulcanization retarder. In this case, the mass ratio of the amount of the triazine compound to the amount of N-cyclohexylthiophthalimide (triazine compound / N-cyclohexylthiophthalimide) is preferably 0.5 or more, more preferably 1 or more, and is preferably 10 or less, more preferably 5 or less.

[0046] 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).

[0047] Examples of the antioxidant include nickel diethyldithiocarbamate and nickel dibutyldithiocarbamate.

[0048] The rubber composition for a paper feed roller can be prepared by blending (A) base rubber, (B) vulcanizing agent, and other raw materials as necessary, and kneading them using a pressure kneader, Banbury mixer, open roll, etc. The kneading method and conditions are appropriately selected depending on the production scale.

[0049] The hardness (Durometer type A hardness) of the cured product of the rubber composition for paper-feed rollers 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 is suitable for paper feeding, and the conveying force is further improved, and if it is 80 or less, it is easier to press the product onto the roller shaft.

[0050] The cured product of the rubber composition for paper feed rollers has a high coefficient of friction, and the coefficient of friction decreases only slightly even when the rubber composition is repeatedly brought into contact with paper containing a large amount of silicate components such as silica or talc. Therefore, the rubber composition for paper feed rollers can be suitably used as a material for forming paper feed rollers and paper feed belts.

[0051] <Paper feed roller> The paper feed roller of the present disclosure is obtained by curing the rubber composition for a paper feed roller. The shape of the paper feed roller can be cylindrical, columnar, polygonal tubular, or polygonal prism. When the paper feed roller is cylindrical or polygonal tubular, it preferably has a shaft. The material of the shaft is not particularly limited, and examples include metal, ceramic, and resin.

[0052] An example of a paper feed roller is shown in Figure 1. The paper feed roller 1 shown in Figure 1 has a cylindrical roller body 2 and a shaft 4 inserted into a through hole 3 of the roller body 2.

[0053] The roller body 2 can be formed using the rubber composition for a paper feed roller by, for example, press molding, extrusion molding, or the like. In the press molding method, a mold having a cavity corresponding to the three-dimensional shape of the roller body 2 is prepared, and the rubber composition is filled into the cavity of the mold and heated under pressure to crosslink the rubber composition, thereby forming the roller body 2. In the extrusion molding method, the roller body 2 is formed by extruding the rubber composition into a cylindrical shape using an extruder connected to a die corresponding to the cross-sectional shape of the roller body 2, and then crosslinking the extruded rubber composition.

[0054] The roller body 2 and the shaft 4 are integrated together by, for example, forming the outer diameter of the shaft 4 larger than the inner diameter of the through hole 3 of the roller body 2 and pressing the shaft 4 into the through hole 3, or by adhering the two together with an adhesive, or by vulcanizing and adhering them together with a vulcanizing adhesive when the roller body 2 is crosslinked.

[0055] Furthermore, at any time before or after the integration, both ends of the roller body 2 may be cut as needed so that the axial length of the roller body 2, i.e., the width of the paper-feed roller 1, becomes a predetermined value. The roller body 2 may be formed into a two-layer structure consisting of an outer layer on the outer periphery side and an inner layer on the shaft 4 side. In this case, it is sufficient that at least the outer layer is formed from the rubber composition for a paper-feed roller.

[0056] The paper feed roller 1 of the present disclosure can be used as various paper feed rollers such as paper feed rollers, conveying rollers, platen rollers, and paper discharge rollers that are incorporated into paper feed mechanisms in devices such as electrostatic copiers, laser printers, plain paper facsimile machines, and combination machines thereof, as well as image forming devices such as inkjet printers, and even automated teller machines (ATMs). [Example]

[0057] 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.

[0058] [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 to avoid the influence of the measurement substrate, and the hardness was measured using an automatic hardness tester (manufactured by Kobunshi Keiki Co., Ltd.). A "Durometer Type A" was used as the detector.

[0059] (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.

[0060] (3) Roller evaluation <Test Paper> Calcium carbonate-containing paper: 70 g / m 2 (Ash content by TGA analysis: approximately 15% by mass; elemental analysis of ash: calcium accounts for the majority of elements other than oxygen.) Silica (silicate)-containing paper: 80 g / m 2 (Ash content by TGA analysis: approx. 26% by mass. Elemental analysis of ash: Si accounts for the majority of elements other than oxygen. Mg and Ca were also detected.)

[0061] <Friction coefficient measurement> As shown in Figure 2, a piece of paper 11 (width 60 mm × length 210 mm) was placed on a horizontally placed polytetrafluoroethylene (PTFE) plate 10. The roller body 2 of the paper feed 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 a temperature of 23±2°C and a relative humidity of 55±10%, 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)

[0062] <Repeated paper passing mock test> As shown in Figure 3, a belt 14 made by connecting test papers (50 mm wide x 297 mm long) into a ring shape was wound between the roller body 2 of the paper feed roller 1 and a metal driven roller 13 arranged parallel to the paper feed roller 1. The roller body 2 with the belt 14 wound around it was placed on a plate 15 made of polytetrafluoroethylene (PTFE), and a vertical load W2 (= 500 gf) was applied to the shaft 4 to press it against the plate 15. Next, under an environment of a temperature of 23±2°C and a relative humidity of 55±10%, the roller body 2 was rotated at 200 rpm in the direction indicated by the dashed arrow R2, and a simulated paper-passing operation was performed in which the belt 14 was conveyed in the direction indicated by the dashed arrow. The belt 14 was replaced with a new one every 10 minutes of paper-passing operation. The friction coefficient μ of the roller was measured 30 minutes and 60 minutes after the start of the paper feeding operation.

[0063] [Preparation of Rubber Composition] Rubber compositions were prepared by mixing the raw materials using a kneader and an open roll so as to obtain the formulations shown in Tables 1 and 2. Tables 1 and 2 show the measurement results of the cured products of the obtained rubber compositions.

[0064] [Table 1]

[0065] [Table 2]

[0066] The raw materials used in Tables 1 and 2 are as follows: Hydrin rubber 1: Epion (registered trademark) 301L (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer (ethylene oxide content 73 mol%)), manufactured by Osaka Soda Co., Ltd. Hydrin rubber 2: Epichromer (registered trademark) D (epichlorohydrin-ethylene oxide copolymer (ethylene oxide content 61 mol%)), manufactured by Osaka Soda Co., Ltd. Hydrin rubber 3: Hydrin (registered trademark) T3106 (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer (ethylene oxide content 56 mol%)), manufactured by Nippon Zeon Co., Ltd. Hydrin rubber 4: Epichromer CG104 (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer (ethylene oxide content 35.5 mol%)), manufactured by Osaka Soda Co., Ltd. Hydrin rubber 5: Hydrin T1100 (epichlorohydrin-allyl glycidyl ether copolymer), manufactured by Nippon Zeon Co., Ltd. EPDM: Esprene (registered trademark) 505A (ethylene-propylene-ethylidene norbornene copolymer) manufactured by Sumitomo Chemical Co., Ltd. Carbon black: Tokai Carbon Co., Ltd., Seast (registered trademark) 3 Calcium carbonate: BF-300, manufactured by Bihoku Funka Kogyo Co., Ltd. Hydrotalcite: Kyowa Chemical Industry Co., Ltd., DHT-4A-2 Magnesium oxide: Kyowamag (registered trademark) 150, manufactured by Kyowa Chemical Industry Co., Ltd. Calcium oxide: Omi Chemical Industry Co., Ltd., CLM#35 Thiourea compound: Axel (registered trademark) 22-S (ethylene thiourea), manufactured by Kawaguchi Chemical Industry Co., Ltd. Vulcanization retarder 1: Valnoc (registered trademark) R (4,4'-dithiodimorpholine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Triazine compound: Jisnet (registered trademark) F (2,4,6-trimercapto-1,3,5-triazine), manufactured by Sankyo Kasei Co., Ltd. Vulcanization accelerator 1: Noccela (registered trademark) D (1,3-diphenylguanidine), manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization retarder 2: Retarder CTP (N-cyclohexylthiophthalimide), manufactured by Toray Industries, Inc. Sulfur: Tsurumi Chemical Industry Co., Ltd., 5% sulfur with oil Vulcanization accelerator 2: Noccela TOT-N, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 3: Noccela DM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Zinc oxide: Mitsui Mining & Smelting Co., Ltd., zinc oxide type 2 Stearic acid: NOF Corporation, Camellia stearate

[0067] [Manufacturing of paper feed 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 22 mm. The rubber roller portion was then cut to a width of 25 mm to produce a paper feed roller. The evaluation results of the resulting paper feed roller are shown in Tables 1 and 2.

[0068] Rubber compositions Nos. 1 to 5 contain an epichlorohydrin-ethylene oxide copolymer or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer as (A) the base rubber, and contain a thiourea compound as the (B) crosslinking agent. Rubber compositions Nos. 6 to 8 contain an epichlorohydrin-ethylene oxide copolymer or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer as (A) the base rubber, and a triazine compound as (B) the crosslinking agent. The paper feed rollers made using these rubber compositions No. 1 to No. 8 all have a high initial friction coefficient for calcium carbonate-containing paper and silica (silicate)-containing paper, and the decrease in the friction coefficient is suppressed even after repeated paper feed. Therefore, it is thought that conveyance defects are suppressed even when used for a long period of time. In particular, the paper feed rollers made using rubber compositions Nos. 1 to 3 and 6 to 7, which have an average ethylene oxide content of 50% or more, show even less decrease in the friction coefficient when used with silica (silicate)-containing paper, even after repeated paper feed.

[0069] Rubber compositions Nos. 9 and 10 are cases in which the base rubber (A) does not contain an epichlorohydrin-ethylene oxide copolymer and / or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer. Rubber compositions Nos. 11 and 12 do not contain a thiourea compound and / or a triazine compound as the (B) crosslinking agent. Although the paper feed rollers made using these rubber compositions No. 9 to 12 had a high initial friction coefficient with silica (silicate)-containing paper, the friction coefficient decreased significantly after repeated paper feed. Therefore, it is believed that using these paper feed rollers would cause transport problems in a relatively short time.

[0070] The present disclosure (1) is a rubber composition for a paper-feed roller, which contains (A) a base rubber and (B) a vulcanizing agent, wherein the (A) base rubber contains an epichlorohydrin-ethylene oxide copolymer and / or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer, and the (B) vulcanizing agent contains a thiourea compound and / or a triazine compound.

[0071] The present disclosure (2) is the rubber composition for a paper feed roller according to the present disclosure (1), wherein the epichlorohydrin-ethylene oxide copolymer and / or the epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer has an ethylene oxide content of 50 mol% or more.

[0072] The present disclosure (3) is a rubber composition for a paper feed roller according to the present disclosure (1) or (2), in which the total content of epichlorohydrin-ethylene oxide copolymer and / or epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer in the base rubber (A) is 85 mass% or more.

[0073] The present disclosure (4) is a rubber composition for a paper feed roller according to any one of the present disclosures (1) to (3), wherein the amount of the thiourea compound and / or the triazine compound is 0.1 to 10 parts by mass per 100 parts by mass of the (A) base rubber.

[0074] The present disclosure (5) is a paper-feeding roller obtained by curing the rubber composition for a paper-feeding roller according to any one of the present disclosures (1) to (4). [Explanation of symbols]

[0075] 1: Paper feed roller, 2: Roller body, 3: Through hole, 4: Shaft, 10: Plate, 11: Paper, 12: Load cell, 13: Driven roller, 14: Belt, 15: Plate

Claims

1. (A) a base rubber; and (B) a vulcanizing agent, the (A) base rubber contains an epichlorohydrin-ethylene oxide copolymer and / or an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer, the (A) base rubber contains epichlorohydrin-ethylene oxide copolymer and / or epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer in a total amount of 85% by mass or more, the epichlorohydrin-ethylene oxide copolymer and / or the epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer has an ethylene oxide content of 55 mol% or more; When the (A) base rubber contains another rubber component other than an epichlorohydrin-ethylene oxide copolymer and an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer, the other rubber component is at least one selected from the group consisting of an epichlorohydrin homopolymer, an epichlorohydrin-allyl glycidyl ether copolymer, an epichlorohydrin-propylene oxide copolymer, an epichlorohydrin-propylene oxide-allyl glycidyl ether copolymer, an ethylene-propylene-diene copolymer, an ethylene-butene copolymer, an ethylene-octene copolymer, an ethylene-propylene-butene copolymer, an ethylene-butene-diene copolymer, an ethylene-propylene-butene-diene copolymer, an acrylonitrile-butadiene rubber, a styrene-butadiene rubber, an acrylic rubber, a butyl rubber, and a silicone rubber, The vulcanizing agent (B) contains a thiourea compound represented by formula (1) or a triazine compound represented by formula (2), A rubber composition for a paper-feed roller, characterized in that the amount of the thiourea compound or triazine compound blended is 0.5 to 2 parts by mass per 100 parts by mass of the base rubber (A). 【Chemical 1】 [In formula (1), R 1 to R 4 each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. R 2 and R 3 may be bonded to each other.] 【Chemistry 2】 [In formula (2), X 1 and X 2 each independently represent a thiol group or a —NR 11 R 12 group, where R 11 and R 12 each independently represent an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 10 carbon atoms.]

2. 2. The rubber composition for a paper-feed roller according to claim 1, wherein the total content of the epichlorohydrin-ethylene oxide copolymer and / or the epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer in the base rubber (A) is 95% by mass or more.

3. The acid acceptor contains at least one selected from the group consisting of hydrotalcite, magnesium oxide, calcium oxide, calcium hydroxide, and magnesium hydroxide, 3. The rubber composition for a paper-feed roller according to claim 1, wherein the content of the acid acceptor is 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the base rubber (A).

4. A paper feed roller obtained by curing a rubber composition for a paper feed roller described in any one of claims 1 to 3.

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