Flat belt for transporting paper sheets

Abstract

To provide a flat belt for conveying paper sheets excellent in oil resistance.SOLUTION: The flat belt for conveying paper sheets includes a base rubber layer, and a conveying surface side layer formed on the base rubber layer. The conveying surface side layer includes a rubber cement composition containing NBR as a main component, and a knitted fabric. The knitted fabric comprises a composite yarn that consists of a core yarn made of urethane fiber and a covering yarn made of polyester fiber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flat belt for conveying paper sheets. [Background technology]

[0002] Paper sheet conveying devices such as automated teller machines, vending machines, currency exchange machines, ticket vending machines, cash registers, etc. use flat belts for conveying paper sheets such as banknotes, credit cards, tickets, etc. The flat belts for conveying paper sheets are suspended between a plurality of drive pulleys and guide pulleys whose axes are fixed so as to face each other, and when the opposing flat belts for conveying paper sheets run in close contact with each other, the clamping force between the belts conveys paper sheets such as banknotes and tickets in the direction of belt travel. Banknotes and credit cards may have oils and grease from skin, food, etc., adhering to their surfaces, and tickets may not be sufficiently dry when conveyed immediately after printing. For example, a flat belt for conveying paper sheets may swell due to the oils adhering to the paper sheets permeating the belt after long-term use. The swelling of the flat belt for conveying paper sheets may cause conveyance problems.

[0003] Furthermore, since paper sheet transport devices are installed in a variety of environments, it is naturally required that they be able to stably transport paper sheets even in various environments. In Patent Document 1, the present inventors have proposed an endless belt for transporting paper sheets, which has a small change in elastic modulus even at low temperatures compared to normal temperatures and can stably transport paper sheets even in cold regions or during the winter. On the other hand, due to the rise in average temperatures caused by global warming and increased demand in Southeast Asian countries, in recent years, flat belts for transporting paper sheets are sometimes required to have moisture and heat resistance so that they can stably transport paper sheets even under high-temperature and high-humidity conditions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-256587 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a flat belt for conveying paper sheets (hereinafter also simply referred to as a flat belt) that has excellent oil resistance. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention has the following configuration. 1. A base rubber layer and a conveying surface side layer formed on the base rubber layer, the conveying surface side layer comprises a glue rubber composition containing NBR as a main component and a knitted fabric, The flat belt for conveying paper sheets, wherein the knitted fabric is made of a composite yarn having a core yarn of urethane fiber and a covering yarn of polyester fiber. 2. The flat belt for conveying paper sheets according to 1., wherein the ratio of the initial elastic modulus to the elastic modulus before break (initial elastic modulus / elastic modulus before break) is 1.2 or more. 3. The flat belt for conveying paper sheets according to 1. or 2., characterized in that the initial elastic modulus is 10 MPa or more. 4. The flat belt for conveying paper sheets according to any one of 1. to 3., wherein the flat belt has an elongation of 1.6% or less after being run for 1 hour at 25°C, a load of 22 N, and a speed of 5.9 m / sec using an 8-axis running tester. 5. A flat belt for conveying banknotes, comprising the flat belt for conveying paper sheets according to any one of 1. to 4. [Effects of the Invention]

[0007] The flat belt for conveying paper sheets of the present invention has excellent oil resistance, is not likely to swell even when it comes into contact with oil, and is less likely to cause conveying defects.The flat belt for conveying paper sheets of the present invention has excellent moist heat resistance, and can stably perform even in high-temperature and high-humidity environments.Furthermore, the flat belt for conveying paper sheets of the present invention, which has a ratio of the initial elastic modulus to the pre-break elastic modulus (initial elastic modulus / pre-break elastic modulus) of 1.2 or more, can be driven stably and is not likely to fall off the pulley, thereby reducing the frequency of replacement and maintenance. The flat belt for conveying paper sheets of the present invention can be used to convey paper sheets such as banknotes, credit cards, tickets, etc., and is particularly suitable for conveying banknotes. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a flat belt for conveying paper sheets according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram of a flat belt for conveying paper sheets according to an embodiment of the present invention, viewed from the conveying surface side; [Figure 3] Layout of a running test machine used in a belt elongation test in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1 and 2 are schematic diagrams of a flat belt 1 for conveying paper sheets according to one embodiment of the present invention. Note that what is shown in Figures 1 and 2 is merely a schematic diagram and does not reflect the actual dimensions. A flat belt 1 for conveying paper sheets according to one embodiment includes a base rubber layer 11 and a conveying surface side layer 12 formed on the base rubber layer 11, The conveying surface side layer 12 includes a glue rubber composition 122 containing NBR as a main component and a knitted fabric 121, The knitted fabric 121 is characterized by being made of a composite yarn with a urethane fiber as the core yarn and a polyester fiber as the covering yarn. In this specification, the expression A to B (A and B are numerical values) means a numerical range including A and B, that is, A or more and B or less.

[0010] The size of the paper sheet conveying flat belt 1 can be adjusted appropriately depending on the size of the object to be conveyed, but for example, the circumferential length is about 50 mm to 4000 mm, the width is about 2 mm to 400 mm, and the thickness is about 0.2 mm to 5 mm. In particular, to save space, the thickness is preferably 3 mm or less, more preferably 2.5 mm or less, and even more preferably 2 mm or less. However, if the thickness is too thin, the strength decreases, so the thickness is preferably 0.4 mm or more.

[0011] "Base rubber layer" The base rubber layer 11 is formed from a base rubber composition containing a rubber component, a crosslinking agent, and the like. The ratio of the thickness of the base rubber layer 11 to the total thickness of the flat belt 1 is preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more. The rubber component can be any rubber component without particular limitation as long as it does not impair the effects of the present invention, and can be, for example, one or a mixture of two or more of known rubbers such as natural rubber (NR), nitrile rubber (NBR), ethylene propylene diene rubber (EPDM), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber (CR), etc. Among these, a rubber containing NBR and EPDM in a mass ratio of 10 / 90 to 90 / 10 is preferred.

[0012] Nitrile rubber (NBR) NBR is a copolymer of acrylonitrile and 1,3-butadiene. The composition ratio of acrylonitrile and 1,3-butadiene can be adjusted appropriately depending on processability and desired physical properties. For example, from the viewpoint of swelling resistance and moist heat resistance, the acrylonitrile content is preferably 12% by mass or more and 45% by mass or less, and more preferably 30% by mass or more and 40% by mass or less. One type of NBR can be used alone, or two or more types can be mixed together.

[0013] Ethylene propylene diene rubber (EPDM) EPDM is a terpolymer of ethylene, propylene, and a diene. The composition ratio of ethylene to propylene can be adjusted appropriately depending on processability and desired physical properties. For example, from the viewpoints of swelling property and wet heat resistance, an ethylene content of 40% by mass or more and 58% by mass or less is preferable. Furthermore, as the diene component, dicyclopentadiene (DCPD), 5-ethylidene-2-norbornene (ENB), 1,4-hexadiene (1,4-HD), etc. can be used. Among these, an ENB content of 4% by mass or more and 12% by mass or less is preferable because of its high elasticity. One type of EPDM or a mixture of two or more types of EPDM can be used.

[0014] The base rubber composition contains NBR and EPDM as rubber components in a mass ratio of 10 / 90 to 90 / 10, so that the various physical properties required for a flat belt for conveying paper sheets can be exhibited in a well-balanced manner. The mass ratio of NBR to EPDM is preferably 70 / 30 to 55 / 45.

[0015] The base rubber composition preferably contains a plasticizer, which can prevent the base rubber 11 from decreasing in tensile strength. The plasticizer to be used is not particularly limited as long as it exerts its effect, and examples thereof include synthetic plasticizers such as phthalate esters, aliphatic dibasic acid esters, trimellitate esters, ether esters, polyether esters, and polyesters, and petroleum-based softeners such as naphthenes, aromatics, and paraffins. Examples of phthalate esters include dibutyl phthalate (DBP), di(2-ethylhexyl) phthalate (DOP), and diisononyl phthalate (DINP). Examples of aliphatic dibasic acid esters include di(2-ethylhexyl) adipate (DOA), dibutyl sebacate (DBS), and di(2-ethylhexyl) sebacate (DOS). Examples of trimellitate esters include tri-2-ethylhexyl totimellate (TOTM) and tridecyl trimellitate (TDTM). Examples of ether esters include adipic acid ether esters. Examples of polyesters include adipate polyesters and sebacate polyesters. Commercially available products can be used for these, and examples of polyether esters include Adekacizer RS-700, RS-735, RS-966, and RS-1000. The amount of plasticizer to be added is not particularly limited as long as it exerts its effect, but is preferably 3% by mass or more, and more preferably 5% by mass or more, based on 100% by mass of the rubber component. The upper limit of this amount is approximately 25% by mass or less. Adding more plasticizer will saturate its effect and provide almost no improvement in performance, and it may bleed onto the rubber surface, resulting in higher costs.

[0016] The base rubber composition is intermolecularly crosslinked, and organic peroxides, sulfur, or a combination of these can be used as a crosslinking agent. The base rubber composition may also be crosslinked using electron beams or the like. Among these, organic peroxides are preferred from the standpoint of abrasion resistance. Specific examples include di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α,α'-bis(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyldi(t-butyl)hexyne, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxyisopropyl carbonate, and 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane. One or more of these organic peroxides can be used in combination. The amount of the organic peroxide mixed is usually, for example, about 1% by mass or more and 8% by mass or less relative to 100% by mass of the rubber component.

[0017] The base rubber composition may contain one or more inorganic particles, such as silica, carbon black, titanium oxide, aluminum oxide, calcium carbonate, magnesium carbonate, zinc carbonate, barium sulfate, diatomaceous earth, clay, talc, and zinc oxide. In rubber compositions containing NBR and EPDM, inorganic particles tend to collect at the interface of the sea-island structure formed by the NBR and EPDM, which can reduce the strength at the interface. The rubber composition of the present invention has excellent strength at the interface of the sea-island structure formed by the NBR and EPDM, so that the reduction in strength can be minimized even when inorganic particles are incorporated. The amount of inorganic particles incorporated is preferably 10% by mass or more, more preferably 20% by mass or more, based on 100% by mass of the rubber component. The upper limit of this amount is preferably 100% by mass or less, more preferably 90% by mass or less. Carbon black is preferably used as the inorganic particles in terms of imparting conductivity, reinforcement, and resistance to UV degradation. The carbon black to be blended is not particularly limited, and examples thereof include channel black; furnace blacks such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234; thermal blacks such as FT and MT; acetylene black, Ketjenblack EC300J, and Ketjenblack EC600JD.

[0018] The base rubber composition may also contain processing aids, vulcanization accelerators, vulcanization acceleration aids, antioxidants, scorch inhibitors, ultraviolet absorbers, light stabilizers, softeners, foaming agents, foaming aids, lubricants, flame retardants, antistatic agents, colorants, etc. Examples of processing aids include stearic acid, polyethylene wax, and metal salts of fatty acids. One or more of these processing aids can be used. The content of the processing aid is, for example, 0.5% by mass or more and 2% by mass or less relative to 100% by mass of the rubber component. Examples of vulcanization accelerators include thiuram-based accelerators (e.g., TETD, TT, TRA, etc.), thiazole-based accelerators (e.g., MBT, MBTS, etc.), sulfenamide-based accelerators (e.g., CZ, etc.), and dithiocarbamate-based accelerators (e.g., BZ-P, etc.). One or more of these vulcanization accelerators can be used. The content of the vulcanization accelerator is, for example, 2% by mass or more and 5% by mass or less relative to 100% by mass of the rubber component.

[0019] Examples of the vulcanization accelerator include metal oxides such as zinc oxide (zinc white) and magnesium oxide, metal carbonates, fatty acids and their derivatives. One or more of these vulcanization accelerators can be used. The content of the vulcanization accelerator is 3% by mass or more and 7% by mass or less based on 100% by mass of the rubber component. Examples of the antioxidant include amine-ketone antioxidants, diamine antioxidants, and phenolic antioxidants. One or more of these antioxidants can be used. The content of the antioxidant is 0.1% by mass or more and 5% by mass or less based on 100% by mass of the rubber component.

[0020] "Conveying surface side layer" The conveying surface side layer 12 is a layer whose surface comes into contact with the paper sheets during conveyance. The conveying surface side layer 12 is formed on the base rubber layer 11 and includes a glue rubber composition 122 containing NBR as a main component and a knitted fabric 121. "Mainly containing NBR" means that the glue rubber composition contains 70% by mass or more of NBR relative to 100% by mass of the rubber component. ·Glue rubber composition The rubber glue composition 122 is sized onto the knitted fabric 121 in an uncrosslinked state by a known method, and then crosslinked to be integrated with the knitted fabric 121 to form the conveying surface side layer 12 . The glue rubber composition 122 contains NBR as a main component. The same NBR as described above can be used as this NBR. When the base rubber layer 11 contains NBR, the NBR contained in the glue rubber composition 122 and the NBR contained in the base rubber layer 11 may have the same composition or different compositions. The glue rubber composition 122 may contain the same plasticizers, crosslinking agents, inorganic particles, processing aids, vulcanization accelerators, vulcanization acceleration aids, antioxidants, scorch inhibitors, UV absorbers, light stabilizers, softeners, foaming agents, foaming aids, lubricants, flame retardants, antistatic agents, colorants, etc. as the base rubber layer 11. The glue rubber composition 122 may contain rubber components other than NBR as long as the effects of the present invention are not impaired, but it preferably contains 80% by mass or more of NBR relative to 100% by mass of the rubber component, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more.

[0021] The glue rubber composition 122 can contain isocyanate. When the glue rubber composition 122 contains isocyanate, a chemical bond derived from the isocyanate is formed between the glue rubber composition 122 and the knitted fabric 121, or between the glue rubber composition 122 and the base rubber layer 11, thereby improving the adhesive strength at the interface and, as a result, improving the physical properties of the flat belt 1. The isocyanate contained in the glue rubber composition 122 is not particularly limited, but is preferably divalent or higher. For example, aliphatic polyisocyanate compounds such as 1,6-hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexamethylene diisocyanate, lysine methyl ester diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 1,5-octylene diisocyanate, and dimer acid diisocyanate; 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI), hydrogenated tolylene diisocyanate, 2,4 or 2,6-methylcyclohexane diisocyanate, isopropylidenedicyclohexyl-4,4'-diisocyanate, 4,4'-methylenebis(cyclo alicyclic polyisocyanate compounds such as 2,4- or 2,6-tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate, cyclohexanephenylene diisocyanate, triphenylmethane triisocyanate, tris(4-phenylisocyanate)thiophosphate, tolidine diisocyanate, p-phenylene diisocyanate, diphenyl ether diisocyanate, diphenyl sulfone diisocyanate, and other aromatic polyisocyanate compounds. The amount of isocyanate in the glue rubber composition 122 is not particularly limited as long as it is within a range that produces its effect, but for example, it is preferably 3 wt% or more and 50 wt% or less, and more preferably 5 wt% or more and 45 wt% or less, relative to the glue rubber composition other than isocyanate.

[0022] ·Knitted fabric Knitted fabric 121 is made of a composite yarn with a urethane fiber core yarn and a polyester fiber sheath yarn. As shown in FIG. 2, knitted fabric 121 is a cloth formed by knitting a single composite yarn, and has excellent elasticity. Furthermore, because this composite yarn itself has excellent elasticity, knitted fabric 121 made of this composite yarn has very high elasticity. Furthermore, because knitted fabric 121 has no seams, its strength is uniform, and it is possible to prevent the occurrence of weak areas that could become the starting point for tears or cracks. The thickness of the knitted fabric 121 is preferably about 0.1 to 0.7 mm. The thickness of the composite yarn forming the knitted fabric 121 can be adjusted depending on the thickness of the flat belt 1, and is, for example, about 20 to 280T (decitex).

[0023] The knitted fabric 121 is preferably treated with an isocyanate. The method of isocyanate treatment is not particularly limited as long as it is a method that adheres isocyanate to the knitted fabric 121, and examples thereof include immersion in a solution containing an isocyanate and application of a solution containing an isocyanate. This generates a chemical bond derived from the isocyanate between the knitted fabric 121 and the glue rubber composition 122, thereby improving the adhesive strength at the interface and, as a result, improving the physical properties of the flat belt 1. The isocyanate used may be the same as the isocyanate contained in the glue rubber composition 122 described above. The isocyanate used to treat the knitted fabric 121 and the isocyanate contained in the glue rubber composition 122 may be the same compound or different compounds. The isocyanate concentration in the solution into which the knitted fabric 121 is immersed or applied is not particularly limited as long as it is within a range that produces its effect, but examples include 0.5 wt% or more and 50 wt% or less, and preferably 1 wt% or more and 30 wt% or less.

[0024] The flat belt 1 preferably has a large initial elastic modulus in a tensile test and a pre-break elastic modulus smaller than the initial elastic modulus. The elastic modulus is calculated from the slope of data on a stress-strain curve with the horizontal axis representing strain and the vertical axis representing stress. The initial elastic modulus is the slope of a linear approximation of data for strains of 0 to 10%, and the pre-break elastic modulus is the slope of a linear approximation of data for strains of 90 to 100% (at break), assuming that the strain (elongation) at break is 100%. The initial elastic modulus is preferably 10 MPa or more, more preferably 12 MPa or more, even more preferably 15 MPa or more, and even more preferably 18 MPa or more. The pre-break elastic modulus is preferably 2 MPa or more smaller than the initial elastic modulus, more preferably 5 MPa or more smaller, even more preferably 8 MPa or more smaller, and even more preferably 10 MPa or more smaller. The lower limit of the pre-break elastic modulus is preferably 1 MPa or more, and more preferably 1.5 MPa or more. Furthermore, the ratio of the initial elastic modulus to the elastic modulus before break (initial elastic modulus / elastic modulus before break) is preferably 1.2 or more, more preferably 1.6 or more, even more preferably 2.0 or more, and even more preferably 2.5 or more. The paper sheet conveying flat belt 1 is suspended on a pulley in a slightly stretched state, and is driven in close contact with the pulley by its elastic force. When the values ​​of the initial elastic modulus and pre-break elastic modulus are within the above-mentioned ranges, the flat belt 1 can be driven stably, and the flat belt 1 can be prevented from falling off the pulley, thereby reducing the frequency of replacement and maintenance.

[0025] The flat belt 1 has an absolute value of a volume change rate of preferably 3% or less, more preferably 2.5% or less, and even more preferably 2% or less after being immersed in linseed oil at 80° C. for 24 hours. The paper sheet conveying flat belt 1 often comes into contact with oil, but if the volume change rate is 3% or less, the flat belt 1 is less likely to swell even when it comes into contact with oil, and can convey paper sheets stably for a long period of time, while reducing the frequency of replacement. The flat belt 1 is preferably left standing at 70°C and 95% RH for 840 hours (35 days), and the rate of change in tensile strength measured before and after (after standing / before standing) is 90% or more, more preferably 92% or more, and even more preferably 94% or more. When this tensile strength ratio is 90% or more, the flat belt 1 can maintain its elasticity even in a high-temperature, high-humidity environment, allowing it to be used for a long period of time and reducing the frequency of replacement. The flat belt 1 has a belt elongation of preferably 1.6% or less, more preferably 1.3% or less, even more preferably 1% or less, and even more preferably 0.8% or less, as measured by the method described in the examples below. When the belt elongation is 1.6% or less, the flat belt 1 can be prevented from falling off the pulley, and the replacement frequency can be reduced.

[0026] ·Manufacturing method The flat belt 1 can be produced by a known method, for example, by the following method. Various materials are kneaded to obtain an uncrosslinked base rubber composition, which is then formed into a sheet to obtain an uncrosslinked base rubber sheet. A cylindrical knitted fabric 121 is prepared and isocyanate-treated as needed. An uncrosslinked glue rubber composition containing NBR and, if necessary, isocyanate is dissolved in an organic solvent such as toluene or MEK, and the solution is applied to the knitted fabric and dried for sizing. The isocyanate treatment and sizing can be performed either before or after the knitted fabric 121 is placed on the outer periphery of the cylindrical mold. An uncrosslinked base rubber sheet is wrapped around a sized knitted fabric 121 covering the outer periphery of the mold. After wrapping release paper around this periphery, a rubber sleeve is placed on top of that, and the whole is placed in a vulcanizer can and sealed. High-temperature, high-pressure steam is filled into the vulcanizer can and maintained in this state for a predetermined time. The temperature inside the vulcanizer is, for example, 100°C or higher and 200°C or lower, and the pressure is, for example, 1.5 MPa or lower. The processing time is, for example, 5 minutes or higher and 60 minutes or lower. This allows the crosslinking reaction to proceed. The obtained cylindrical slab is then removed from the mold, cut into rings of a predetermined width, and turned over to obtain a flat belt 1 for conveying paper sheets. [Example]

[0027] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. "Example 1" An uncrosslinked base rubber composition was obtained by kneading 110 parts by mass of an NBR and EPDM polymer alloy (NE60, manufactured by JSR Corporation, NBR:EPDM = 60:40), 10 parts by mass of a polyether ester plasticizer (ADEKA Corporation, Adeka Cizer RS700), 60 parts by mass of carbon black FEF (manufactured by Tokai Carbon Co., Ltd., product name: Seest SO), 1 part by mass of stearic acid, 4 parts by mass of a crosslinking agent (NOF Corporation, Parmicle D), and 0.5 parts by mass of oil sulfur in an internal kneader.

[0028] An uncrosslinked glue rubber composition 1 was obtained by kneading 100 parts by mass of NBR (N230S manufactured by JSR Corporation), 13.3 parts by mass of a polyetherester plasticizer (ADEKA Cizer RS107 manufactured by ADEKA Corporation), 12 parts by mass of carbon black FEF (product name: Seest SO manufactured by Tokai Carbon Co., Ltd.), 12 parts by mass of carbon black (product name: Denka Black manufactured by Denka Corporation), 20 parts by mass of light calcium carbonate, 1 part by mass of stearic acid, 3 parts by mass of an antioxidant (product name: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 3 parts by mass of an antioxidant (product name: Nocrac 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 15 parts by mass of clay (product name: Dexy Clay manufactured by RTVANDERBILT), 5 parts by mass of zinc oxide, 4 parts by mass of a crosslinking agent (Purmicle D manufactured by NOF Corporation), and 2 parts by mass of a co-crosslinking agent (product name: Valnoc PM manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) in an internal kneader. The uncrosslinked glue rubber composition 1 was dissolved in MEK at a solid content of 25 wt % to obtain a glue rubber coating liquid. A 0.25mm thick knitted fabric (0.2mm thick composite yarn with a urethane fiber core and a polyester fiber covering) was coated with a rubber glue coating solution at a solid content of 85g / m 2 The coating was applied so that the coating became smooth and dried.

[0029] ·Flat belt manufacturing method Using these, the crosslinking reaction was carried out by treating at 160°C, 0.8 MPa, and 30 minutes according to the manufacturing method described above, to obtain a flat belt for conveying paper sheets with a circumference of 406 mm, a width of 10 mm, and a thickness of 0.65 mm (thickness of the base rubber: 0.4 mm).

[0030] "Comparative Example 1" A flat belt for conveying paper sheets was obtained in the same manner as in Example 1, except that the base rubber composition of Example 1 was used as the glue rubber composition instead of the glue rubber composition 1.

[0031] "Comparative Example 2" An uncrosslinked EPDM rubber composition was obtained by kneading 100 parts by mass of EPDM (Nordel 4640, manufactured by The Dow Chemical Company), 10 parts by mass of a petroleum-based softener (SUNPAR 2280, manufactured by Japan Sun Oil Co., Ltd.), 60 parts by mass of carbon black FEF (Seast SO, manufactured by Tokai Carbon Co., Ltd.), 0.2 parts by mass of stearic acid, 5 parts by mass of zinc oxide, 2 parts by mass of an antioxidant (Nocrac MB, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 5 parts by mass of a crosslinker (Hi-Cross M, manufactured by Seiko Chemical Co., Ltd.), 8 parts by mass of a crosslinker (Perhexa 25B-40, manufactured by Nippon Oil & Fats Co., Ltd.), and 0.5 parts by mass of a processing aid (Struktol WB16, manufactured by S&S Japan Co., Ltd.) in an internal kneader. A flat belt for conveying paper sheets was obtained in the same manner as in Example 1, except that this EPDM rubber composition was used as the base rubber composition and the glue rubber composition.

[0032] "Comparative Example 3" Millable urethane (manufactured by Unimatec Co., Ltd., Knoxtite MU640S), 100 parts by weight, carbon black (manufactured by Tokai Carbon Co., Ltd., Toka Black 5500), 3 parts by weight, polyether ester plasticizer (manufactured by ADEKA Corporation, Adeka Cizer RS107), 6.5 parts by weight, crosslinking agent (manufactured by NOF Corporation, Parmicle D), 3 parts by weight, crosslinking agent (manufactured by Mitsubishi Chemical Corporation, Acryester ED), 1 part by weight, processing aid (manufactured by S&S Japan Co., Ltd., Struktol WB16), 1 part by weight, processing aid (manufactured by Fuso Chemical Co., Ltd., Plastrodin S), 3 parts by weight, hydrolysis stabilizer (manufactured by Hiraizumi Yoko Co., Ltd., Stabaxol P), and 1 part by weight, surfactant (manufactured by AGC Seimi Chemical Co., Ltd., Surflon KH-40), were kneaded in an internal kneader to obtain an uncrosslinked millable urethane rubber composition. A flat belt for conveying paper sheets was obtained in the same manner as in Example 1, except that this millable urethane rubber composition was used as the base rubber composition and the glue rubber composition.

[0033] The obtained flat belt for conveying paper sheets was evaluated as follows, and the results are shown in Table 1. ·Oil resistance The obtained flat belt (circumferential length 406 mm, width 10 mm, thickness 0.65 mm) was immersed in linseed oil (manufactured by Yamakei Sangyo Co., Ltd.) for 24 hours at 80° C. Thereafter, the surface of the removed test piece was thoroughly wiped with a cloth, and then the mass in air and the mass in water were measured, and the volume change rate before and after immersion was calculated using the following formula (1). (Formula 1) JPEG0007788826000001.jpg27168 (However, ΔV 100 is the rate of volume change, m1 is the mass in air before immersion, m2 is the mass in water before immersion (the mass of the weight is added), m3 is the mass in air after immersion, m4 is the mass in water after immersion (the mass of the weight is added), and m5 is the mass of the weight in water.

[0034] Initial modulus of elasticity, modulus of elasticity before breakage, strength retention A strip-shaped sample, 10 mm wide and 200 mm long, was prepared with the length aligned with the circumferential direction of the flat belt. A tensile test was conducted in accordance with JIS-K7312 at a tensile speed of 50 mm / min to measure the tensile strength at break (TB). The strain at break (elongation) was set to 100%, and the initial modulus of elasticity was calculated from the data for strains of 0 to 10%, while the pre-break modulus of elasticity was calculated from the data for strains of 90 to 100%. Measurements were conducted on three samples at a temperature of 23°C and a humidity of 50% RH, and the arithmetic mean of the measured values ​​was shown. Furthermore, for samples that had been left standing at 70°C and 95% RH for 840 hours (35 days), the tensile strength at break (TB) was measured in the same manner before and after leaving the sample, and the strength retention rate was calculated from the rate of change in the tensile strength at break (after leaving the sample / before leaving the sample). The higher the strength retention rate, the better the wet heat resistance.

[0035] Belt stretch Using an 8-axis running test machine, a flat belt with a circumference of 406 mm, width of 10 mm, and thickness of 0.65 mm was run at 25°C and a load of 22 N at a speed of 5.9 m / s for 1 hour, and the belt elongation was measured before and after the run. The layout of the 8-axis running test machine is shown in Figure 3.

[0036] [Table 1]

[0037] The flat belt obtained in Example 1 of the present invention was excellent in oil resistance and wet heat resistance. In addition, the elastic modulus and elongation were appropriate, making it suitable as a paper sheet transport belt. In contrast, the flat belts obtained in Comparative Examples 1 to 3 all had poor oil resistance, and the flat belt obtained in Comparative Example 3 also had poor moist heat resistance.

[0038] "Example 2" The knitted fabric was immersed in 1 wt % of isocyanate (Hardrion RFE, manufactured by Hiraizumi Yoko Co., Ltd.) in toluene and dried at 25°C for isocyanate treatment. A flat belt for conveying paper sheets was obtained in the same manner as in Example 1, except that this isocyanate-treated knitted fabric was used.

[0039] "Example 3" A flat belt for conveying paper sheets was obtained in the same manner as in Example 2, except that the isocyanate treatment was carried out with a 2 wt % toluene solution.

[0040] Example 4 100 parts by mass of NBR (N230S, manufactured by JSR Corporation), 13.3 parts by mass of polyether ester plasticizer (ADEKA Cizer RS107, manufactured by ADEKA Corporation), 43.3 parts by mass of carbon black HAF (SEAST 3, manufactured by Tokai Carbon Co., Ltd.), 23.3 parts by mass of carbon black (Denka Company, trade name: DENKA BLACK), 21.7 parts by mass of light calcium carbonate, 1 part by mass of stearic acid, 3 parts by mass of antioxidant (Sunnock N, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 3 parts by mass of antioxidant (Nocrac 6C, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 15 parts by mass of clay (Dexy Clay, manufactured by RTVANDERBILT), 5 parts by mass of zinc oxide, 4 parts by mass of crosslinking agent (Permicle D, manufactured by NOF Corporation), and 5 parts by mass of co-crosslinking agent (Vulnoc PM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were kneaded in an internal kneader to obtain an uncrosslinked glue rubber composition 2. A flat belt for conveying paper sheets was obtained in the same manner as in Example 1, except that glue rubber composition 2 was used instead of glue rubber composition 1.

[0041] "Example 5" A flat belt for conveying paper sheets was obtained in the same manner as in Example 2, except that glue rubber composition 2 was used. A flat belt for conveying paper sheets was obtained in the same manner as in Example 3, except that glue rubber composition 2 was used.

[0042] "Example 7" Isocyanate (manufactured by Hiraizumi Yoko Co., Ltd., trade name: Hardlion RFE) was added to the glue rubber composition 2 so as to be 5 wt %. A flat belt for conveying paper sheets was obtained in the same manner as in Example 4, except that this glue rubber composition containing isocyanate was used. "Example 8" A flat belt for conveying paper sheets was obtained in the same manner as in Example 7, except that the amount of isocyanate added was 10 wt %. "Example 9" A flat belt for conveying paper sheets was obtained in the same manner as in Example 7, except that the amount of isocyanate added was 15 wt %. "Example 10" A flat belt for conveying paper sheets was obtained in the same manner as in Example 7, except that the amount of isocyanate added was 30 wt %. "Example 11" A flat belt for conveying paper sheets was obtained in the same manner as in Example 7, except that the amount of isocyanate added was 45 wt %.

[0043] The elastic modulus and belt elongation of the obtained flat belt were evaluated in the same manner as above. The results are shown in Table 2. [Table 2] [Explanation of symbols]

[0044] 1 Flat belt for transporting paper sheets 11 Base rubber layer 12 Conveying surface side layer 121 Knitted fabric 122 Glue rubber composition

Claims

1. a base rubber layer and a conveying surface side layer formed on the base rubber layer, the base rubber layer contains, as rubber components, NBR having an acrylonitrile content of 12% by mass or more and 45% by mass or less and EPDM having an ethylene content of 40% by mass or more and 58% by mass or less, in a mass ratio of 10 / 90 to 90 / 10; The plasticizer is contained in an amount of 3% by mass or more and 25% by mass or less relative to 100% by mass of the rubber component, the conveying surface side layer comprises a glue rubber composition containing NBR as a main component and a knitted fabric, The knitted fabric is made of a composite yarn having a urethane fiber core yarn and a polyester fiber cover yarn, A flat belt for conveying paper sheets, characterized by satisfying either or both of the following (1) and (2): (1) The glue rubber composition contains an isocyanate. (2) The knitted fabric is treated with an isocyanate.

2. 2. The flat belt for conveying paper sheets according to claim 1, wherein the ratio of the initial elastic modulus to the elastic modulus before break (initial elastic modulus / elastic modulus before break) is 1.2 or more.

3. 3. The flat belt for conveying paper sheets according to claim 1, wherein the initial elastic modulus is 10 MPa or more.

4. 4. The flat belt for conveying paper sheets according to claim 1, wherein the flat belt has an elongation of 1.6% or less after being run for 1 hour using an 8-axis running tester at 25°C, a load of 22 N, and a speed of 5.9 m / sec.

5. A flat belt for conveying banknotes, comprising the flat belt for conveying paper sheets according to any one of claims 1 to 4.

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