JP2015031315A - Flat belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat belt capable of suppressing deterioration in frictional coefficient of a belt inner peripheral surface while making a portion constituting the belt inner peripheral surface highly elastically efficient.SOLUTION: In a flat belt B, a portion 14 constituting a belt inner peripheral surface with a rubber composition mixed with carbon nanotube is formed. Rubber hardness measured by a type A durometer on the basis of JIS K6253 in the rubber composition forming the portion 14 constituting the belt inner peripheral surface is 80 or more and less than 95, and apparent frictional coefficient of the belt inner peripheral surface is 0.6 or more.

Description

  The present invention relates to a flat belt.

  Carbon nanotubes are being considered for application in many applications, depending on the specific functions they have.

  For example, Patent Document 1 discloses blending carbon nanotubes as a non-halogen flame retardant into a rubber composition for flame retardant belts.

JP 2009-127034 A

  When the flat belt is applied to a high load transmission, a high tension is applied. In order to endure this high tension and suppress the compression deformation of the rubber, it is necessary to increase the elastic modulus (rubber hardness) of the rubber layer on the inner peripheral side to some extent.

  However, when short fibers are blended in order to increase the elastic modulus of the rubber layer on the inner peripheral side or when a large amount of carbon black as a reinforcing agent is blended, there is a problem that the friction coefficient of the inner peripheral surface of the belt decreases.

  In addition, when an ethylene-α-olefin elastomer or hydrogenated acrylonitrile rubber reinforced by blending a metal salt of an α, β-unsaturated organic acid in the rubber layer on the inner circumference side is used, excellent transmission is achieved at the beginning of running. Although it shows the ability, there is a problem that the friction coefficient of the inner peripheral surface of the belt is greatly reduced when traveling for a long time.

  The subject of this invention is providing the flat belt which can aim at the fall suppression of the friction coefficient of a belt internal peripheral surface, increasing the elasticity modulus in the part which comprises a belt internal peripheral surface.

  The present invention is a flat belt in which a portion constituting the inner peripheral surface of a belt is formed of a rubber composition containing carbon nanotubes.

  According to the present invention, since the portion constituting the inner peripheral surface of the belt is formed of a rubber composition containing carbon nanotubes, the portion constituting the inner peripheral surface of the belt is increased in elasticity while increasing the elastic modulus. It is possible to suppress the decrease in the friction coefficient of the peripheral surface.

It is a perspective view of the flat belt of an embodiment. It is explanatory drawing of the measuring method of the apparent friction coefficient of the belt inner peripheral surface of the flat belt of embodiment. (A)-(c) is a perspective view of the modification of the flat belt of embodiment. It is a figure which shows an example of the pulley layout of the belt transmission apparatus using the flat belt of embodiment. (A)-(c) is 1st explanatory drawing which shows the manufacturing method of the flat belt of embodiment. It is the 2nd explanatory view showing the manufacturing method of the flat belt of an embodiment. It is the 3rd explanatory view showing the manufacturing method of the flat belt of an embodiment. (A) And (b) is a perspective view of another modification of the flat belt of an embodiment. (A) And (b) is a perspective view of the modification which has the reinforcement cloth of the flat belt of embodiment. It is a figure which shows the pulley layout of a belt running test machine.

  Hereinafter, embodiments will be described in detail.

  FIG. 1 shows a flat belt B of the embodiment. The flat belt B according to the embodiment is used in applications that require a long life in use under relatively high load conditions such as a drive transmission application such as a blower, a compressor, and a generator, and an auxiliary machine drive application of an automobile. . The flat belt B of the embodiment has, for example, a belt circumferential length of 600 to 3000 mm, a belt width of 10 to 20 mm, and a belt thickness of 2 to 3.5 mm.

  The flat belt B of the embodiment includes a core wire holding layer 11, an outer rubber layer 12 is provided outside the core wire holding layer 11, and an inner intermediate rubber layer 13 is provided inside. The outer peripheral surface of the outer rubber layer 12 constitutes the outer peripheral surface of the belt, while an inner surface rubber layer 14 is further provided inside the inner intermediate rubber layer 13, and the inner peripheral surface of the inner surface rubber layer 14 is It constitutes the inner peripheral surface of the belt. In the flat belt B of the embodiment, the flat belt main body 10 is configured by a laminated structure of these four layers of the core wire holding layer 11, the outer rubber layer 12, the inner intermediate rubber layer 13, and the inner surface rubber layer 14. The innermost inner surface rubber layer 14 corresponds to a portion constituting the inner peripheral surface of the belt. Further, a core wire 15 is embedded in the core wire holding layer 11 so as to form a spiral having a pitch in the belt width direction.

  In the flat belt B of the embodiment, the inner surface rubber layer 14 is formed of a rubber composition containing carbon nanotubes. More specifically, the inner surface rubber layer 14 is crosslinked by a crosslinking agent by heating and pressing an uncrosslinked rubber composition in which various compounding agents containing carbon nanotubes are blended in a rubber component. The rubber composition is formed. The thickness of the inner surface rubber layer 14 is preferably 0.3 mm or more, more preferably 0.5 mm or more, and preferably 2.0 mm or less, more preferably 1.5 mm or less.

  Examples of the rubber component of the rubber composition forming the inner surface rubber layer 14 include ethylene-α-olefin elastomer (EPDM, EBM, EOM, EPR, etc.), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM). And hydrogenated acrylonitrile rubber (H-NBR). Among these, from the viewpoint of heat resistance, ethylene-α-olefin elastomer and hydrogenated acrylonitrile rubber are preferable, and EPDM is particularly preferable. The rubber component of the rubber composition forming the inner surface rubber layer 14 may be composed of a single kind or a plurality of kinds of blend rubbers.

  Examples of the compounding agent include carbon nanotubes (hereinafter referred to as “CNT”), reinforcing agents, plasticizers, process oils, processing aids, anti-aging agents, vulcanization acceleration aids, crosslinking agents, co-crosslinking agents, and the like.

  CNT is a substance in which a six-membered ring network formed of carbon is tubular. The diameter of CNT is generally 1 to 100 nm. Examples of the CNT include multi-wall type multi-wall type multi-wall carbon nanotubes (hereinafter referred to as “MWCNT”) and single-wall graphene single-wall type single-wall carbon nanotubes (hereinafter referred to as “SWCNT”). The rubber composition forming the inner surface rubber layer 14 may be blended with only MWCNT, may be blended with only SWCNT, or may be blended with both of them. Commercially available MWCNTs can be obtained from Hodogaya Chemical Co., Bayer MaterialScience, Nanosil, etc., and commercially available SWCNTs can be obtained from Nippon Zeon Co., Ltd. by the super gloss method.

  Since the reinforcing effect varies depending on the diameter of CNT, the blending amount of CNT is preferably 0.5 parts by mass or more, more preferably 1 part by mass with respect to 100 parts by mass of the rubber component in the case of SWCNT having a diameter of 1 to 3 nm. Part or more, preferably 5 parts by mass or less, more preferably 3.0 parts by mass or less. In the case of MWCNT having a diameter of 10 nm or more and less than 20 nm, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 30 parts by mass or less, more preferably 40 parts by mass with respect to 100 parts by mass of the rubber component. It is below mass parts. In the case of MWCNT having a diameter of 20 nm or more and less than 70 nm, the amount is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and preferably 50 parts by mass or less, more preferably 40 parts by mass with respect to 100 parts by mass of the rubber component. It is below mass parts. In the case of MWCNT having a diameter of 70 nm or more, the amount is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and preferably 80 parts by mass or less, more preferably 60 parts by mass with respect to 100 parts by mass of the rubber component. It is as follows. In addition, from a viewpoint that the change with time of the friction coefficient on the inner peripheral surface of the belt can be reduced with a relatively small amount, the dispersibility into rubber is high, and the cost is also relatively low, the diameter is 10 nm or more and 20 nm. Less than MWCNT is preferred.

  Thus, according to the flat belt B of the embodiment, the inner surface rubber layer 14 constituting the inner peripheral surface of the belt is formed of a rubber composition in which CNT is blended, and even if the CNT is in a small blending amount, the rubber Since the effect of remarkably increasing the elastic modulus of the composition is exhibited, it is possible to suppress the decrease in the friction coefficient of the inner peripheral surface of the belt while increasing the elastic modulus of the inner surface rubber layer 14.

  Examples of the reinforcing agent include carbon black and silica. The rubber composition forming the inner surface rubber layer 14 preferably contains carbon black as a reinforcing agent in addition to CNT.

  Examples of carbon black include furnace blacks such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234; and thermal blacks such as FT and MT. . Among these, FEF and GPF having a slightly larger particle diameter are preferable from the viewpoint of suppressing rubber adhesion to the flat pulley and sound generation during belt running. The carbon black may be a single type or a plurality of types.

  The compounding amount of carbon black is based on 100 parts by mass of the rubber component from the viewpoint of suppressing a decrease in elongation at the time of cutting of the rubber composition forming the inner surface rubber layer 14 and also suppressing a decrease in bending fatigue resistance. The amount is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and preferably 80 parts by mass or less, more preferably 70 parts by mass or less. The blending amount of carbon black with respect to 100 parts by weight of the rubber component is preferably 2 times or more, more preferably 3 times or more, and preferably 60 times or less, with respect to the blending amount of CNT with respect to 100 parts by weight of the rubber component. Preferably it is 15 times or less. The total amount of CNT and carbon black is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, with respect to 100 parts by mass of the rubber component, from the viewpoint of suppressing a decrease in bending fatigue resistance.

  Examples of the plasticizer include dialkyl phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), dialkyl adipates such as dioctyl adipate (DOA), and dialkyl sebacates such as dioctyl sebacate (DOS). The plasticizer may be a single type or a plurality of types. The blending amount of the plasticizer is preferably 0.1 to 40 parts by mass, more preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of the process oil include paraffinic oil, naphthenic oil, and aromatic oil. The process oil may be a single kind or a plurality of kinds. The blending amount of the process oil is preferably 0.1 to 40 parts by mass, more preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of the processing aid include stearic acid, polyethylene wax, and metal salts of fatty acids. The processing aid may be a single type or may be a plurality of types. The blending amount of the processing aid is preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of the antiaging agent include a diamine type antiaging agent and a phenol type antiaging agent. The anti-aging agent may be a single species or a combination of plural species. The amount of the antioxidant is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of the vulcanization acceleration aid include metal oxides such as magnesium oxide and zinc oxide (zinc white), fatty acids such as metal carbonates and stearic acid, and derivatives thereof. The vulcanization acceleration aid may be composed of a single species or a plurality of species. The compounding quantity of a vulcanization | cure acceleration | stimulation adjuvant is 0.5-8 mass parts with respect to 100 mass parts of rubber components.

  Examples of the crosslinking agent include organic peroxides and sulfur. From the viewpoint of enhancing the heat resistance and suppressing the reduction of the friction coefficient on the inner peripheral surface of the belt, an organic peroxide is preferable as the crosslinking agent.

  Examples of the organic peroxide include dialkyl peroxides such as dicumyl peroxide, peroxyesters such as t-butyl peroxyacetate, and ketone peroxides such as dicyclohexanone peroxide. The organic peroxide may be a single species or a plurality of species. The compounding amount of the organic peroxide is preferably 0.5 to 10 parts by mass, more preferably 1 to 6 parts by mass with respect to 100 parts by mass of the rubber component.

  In the case of using an organic peroxide as a cross-linking agent, a rubber for forming the inner surface rubber layer 14 from the viewpoint of increasing the cross-link density, thereby reducing the amount of reinforcing agent such as CNT and carbon black and increasing the elastic modulus. The composition may further contain a co-crosslinking agent.

  Examples of the co-crosslinking agent include trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, triallyl isocyanurate, liquid polybutadiene, N, N′-m-phenylenebismaleimide and the like. The co-crosslinking agent may be a single type or a plurality of types may be added. The compounding amount of the co-crosslinking agent is preferably 0.5 to 10 parts by mass, more preferably 2 to 7 parts by mass with respect to 100 parts by mass of the rubber component. However, the rubber composition forming the inner surface rubber layer 14 does not contain a metal salt of an α, β-unsaturated organic acid such as zinc acrylate or zinc methacrylate, even if it is a co-crosslinking agent. Is preferred. More specifically, the rubber composition forming the inner surface rubber layer 14 is not an ethylene-α-olefin elastomer or hydrogenated acrylonitrile rubber reinforced with a metal salt of an α, β-unsaturated organic acid. Is preferred. Examples of the metal salt of the α, β-unsaturated organic acid include zinc acrylate and zinc methacrylate.

  It is preferable that short fibers are not blended in the rubber composition forming the inner surface rubber layer 14 from the viewpoint of preventing a reduction in the friction coefficient of the inner peripheral surface of the belt. However, the short fiber may be mix | blended with the rubber composition which forms the inner surface rubber layer 14 in the range which does not impair the fall inhibitory effect of the friction coefficient of the belt internal peripheral surface by CNT. In this case, it is preferable that the inner surface rubber layer 14 includes short fibers so as to be oriented in the belt width direction. Examples of such short fibers include cellulose short fibers such as para-aramid short fibers and cotton short fibers, polyester short fibers, and the like. The short fiber may be a single type or a plurality of types. The length of the short fiber is, for example, 1 to 6 mm. The compounding quantity of a short fiber is 1-10 mass parts with respect to 100 mass parts of rubber components.

  In addition to the rubber composition forming the inner surface rubber layer 14, fillers such as calcium carbonate, talc, and diatomaceous earth, stabilizers, coloring agents, and the like may be blended. Cellulose nanofibers, synthetic fiber nanofibers, and the like may be blended in the rubber composition forming the inner surface rubber layer 14, whereby the inner surface rubber layer 14 is maintained while maintaining the friction coefficient of the inner peripheral surface of the belt. High elastic modulus can be achieved.

  The rubber hardness of the rubber composition forming the inner surface rubber layer 14 is preferably 79 or more, more preferably 82 or more, and preferably less than 95, more preferably 92 or less. This rubber hardness is measured by a type A durometer based on JIS K6253.

  The apparent friction coefficient μ ′ of the surface of the inner surface rubber layer 14, that is, the inner peripheral surface of the belt is preferably 0.5 or more, more preferably 0.6 or more, and preferably 1.5 or less, more Preferably it is 1.2 or less. As shown in FIG. 2, this apparent coefficient of friction μ ′ is obtained when the flat belt piece 21 is flat with an outer diameter of 50 to 100 mm so that the surface of the inner surface rubber layer 14, that is, the inner peripheral surface of the belt is in contact. The pulley 22 is wound around the pulley 22 at a winding angle θ, the upper end of the flat belt piece 21 is chucked and connected to the load cell 23, and the lower end hanging vertically is chucked to attach the weight 24. Then, the flat pulley 22 is rotated at a peripheral speed of 20 m / s so as to increase the tension of the portion from the load cell 23 to the flat pulley 22 of the flat belt piece 21 (counterclockwise in FIG. 2), and the weight at that time Based on the Euler equation, the following equation (1) is obtained from the slack side tension Ts 24 and the tension side tension Tt detected by the load cell 23. A method for measuring the apparent friction coefficient μ ′ is described on page 122 of “Practical design of belt transmission, published by Yokodo Co., Ltd.”.

  The core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13 are made of a crosslinking agent by heating and pressurizing an uncrosslinked rubber composition in which various compounding agents are blended with a rubber component. It is formed of a crosslinked rubber composition. The thickness of the core wire holding layer 11 is, for example, 0.6 to 1.5 mm, the thickness of the outer rubber layer 12 is, for example, 0.6 to 1.5 mm, and the thickness of the inner intermediate rubber layer 13 is, for example, 0.6 to 1.5 2.0 mm.

  The rubber component of the rubber composition that forms the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13 is the same as the rubber component of the rubber composition that forms the inner surface rubber layer 14, for example, ethylene- Examples include α-olefin elastomers (EPDM, EPR, etc.), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber (H-NBR), and the like. Among these, from the viewpoint of heat resistance, ethylene-α-olefin elastomer and hydrogenated acrylonitrile rubber are preferable, and EPDM is particularly preferable. The rubber component of the rubber composition forming the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13 may be composed of a single kind or a plurality of kinds of blend rubbers. Also good. The rubber component of the rubber composition forming the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13 is preferably the same, and the same as the rubber component of the rubber composition forming the inner surface rubber layer 14. It is preferable that

  Examples of the compounding agent include a reinforcing agent, a plasticizer, a process oil, a processing aid, an anti-aging agent, a crosslinking agent, a co-crosslinking agent, a vulcanization acceleration aid, a stabilizer, a colorant, and a short fiber.

  The rubber composition forming the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13 may contain CNT, but from the viewpoint of reducing costs, expensive CNT is added. Preferably not.

  As a crosslinking agent mix | blended with the rubber composition which forms the core wire holding layer 11, the outer side rubber layer 12, and the inner side intermediate rubber layer 13, an organic peroxide and sulfur are mentioned. Of these, organic peroxides are preferable from the viewpoint of improving heat resistance.

  When an organic peroxide is used as a crosslinking agent, zinc acrylate, zinc methacrylate, or the like is used as a co-crosslinking agent in the rubber composition that forms the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13. A metal salt of an α, β-unsaturated organic acid may be added. Therefore, the rubber composition for forming the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13 is an ethylene-α-olefin reinforced with a metal salt of an α, β-unsaturated organic acid. It may be an elastomer or a hydrogenated acrylonitrile rubber.

  When the flat belt B is wound around the flat pulley and receives a tension, the inner portion of the core holding layer 11 and the inner intermediate rubber layer 13 receive a large pressing force from the core 15 toward the flat pulley. . When the core wire holding layer 11 and the inner intermediate rubber layer 13 have a low elastic modulus, the core wire 15 sinks inward, and the core wire holding layer 11 and the inner intermediate rubber layer 13 generate heat due to large repetitive deformation. There is a risk of damage. From this viewpoint, it is preferable that the rubber composition forming the core wire holding layer 11 and the inner intermediate rubber layer 13 is blended with short fibers to have a high elastic modulus. Further, in this case, it is preferable that the core fiber holding layer 11 and the inner intermediate rubber layer 13 include short fibers so as to be oriented in the belt width direction. Examples of such short fibers include nylon 6 short fibers, nylon 66 short fibers, polyester short fibers, cotton short fibers, and aramid short fibers. The short fiber may be a single type or a plurality of types. The length of the short fiber is, for example, 1 to 6 mm. The compounding quantity of a short fiber is 10-30 mass parts with respect to 100 mass parts of rubber components. The rubber composition forming the outer rubber layer 12 may be blended with short fibers or may not be blended.

  In the flat belt B of the embodiment, the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13 are formed of the same rubber composition. Therefore, as shown in FIG. 10 may have a laminated structure of two layers of an integrated rubber layer 16 and an inner surface rubber layer 14 in which the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13 are integrally formed. . Further, in the flat belt B of the embodiment, the core wire holding layer 11 and the outer rubber layer 12 are formed of the same rubber composition, and the inner intermediate rubber layer 13 is formed of a rubber composition different from them. As shown in FIG. 3 (b), the flat belt main body 10 is composed of an integrated rubber layer 16, an inner intermediate rubber layer 13 and an inner surface rubber layer 14 in which the core wire holding layer 11 and the outer rubber layer 12 are integrally formed. You may have the laminated structure of a layer. Further, in the flat belt B of the embodiment, the core wire holding layer 11 and the inner intermediate rubber layer 13 are formed of the same rubber composition and the outer rubber layer 12 is formed of a rubber composition different from them. As shown in FIG. 3 (c), the flat belt main body 10 is composed of an integrated rubber layer 16 and an inner surface rubber layer 14 in which the outer rubber layer 12, the core wire holding layer 11 and the inner intermediate rubber layer 13 are integrally formed. You may have the laminated structure of a layer. Further, in the flat belt B of the embodiment, the outer rubber layer 12 and the inner intermediate rubber layer 13 are formed of the same rubber composition, and the core wire holding layer 11 is formed of a rubber composition different from them. The belt body 10 may have a four-layer structure including an outer rubber layer 12, a core wire holding layer 11, an inner intermediate rubber layer 13, and an inner surface rubber layer.

  The core wire 15 may be either embedded in the center in the belt thickness direction, embedded in a side close to the belt inner peripheral surface side, or further embedded in the belt outer peripheral surface side.

  The core 15 is composed of, for example, a polyester fiber such as polyethylene terephthalate fiber (PET) or polyethylene naphthalate fiber (PEN), a twisted yarn such as an aramid fiber, a vinylon fiber, a glass fiber, or a carbon fiber. The outer diameter of the core wire 15 is, for example, 0.1 to 2.0 mm. In order to give the core wire 15 adhesion to the core wire holding layer 11, an adhesive treatment in which the core wire 15 is heated after being immersed in an aqueous solution of resorcin / formalin / latex (hereinafter referred to as “RFL aqueous solution”) and / or before molding. Adhesion treatment is applied to dry after dipping in rubber paste.

  For example, as shown in FIG. 4, the flat belt B of the embodiment having the above configuration is wound around a plurality of flat pulleys 31, 32, and 33 to form a belt transmission device 30. Here, the number of the flat pulleys 31, 32, 33 included in the belt transmission device 30 is, for example, 3 to 8. The outer diameter of the flat pulleys 31, 32, 33 is, for example, 30 to 500 mm. Further, the plurality of flat pulleys 31, 32, 33 of the belt transmission device 30 may include a flat pulley 33 provided so that the belt outer peripheral surface of the flat belt B contacts.

  And in the flat belt B of the embodiment, by appropriate design of the core wire holding layer 11 and the inner intermediate rubber layer 13, the load can be uniformly distributed to the core wire 15, and as a result, even in high load transmission applications, High running stability can be obtained. In addition, the friction coefficient of the belt inner peripheral surface can be set high, and the high friction coefficient can be maintained even after traveling for a long time. In other words, since the reduction of the friction coefficient can be suppressed, The tension can be set low, and as a result, high-efficiency transmission, which is a characteristic of power transmission by the flat belt B, is possible. For example, in combination with a meandering prevention system disclosed in Japanese Patent No. 3680083, maintenance-free operation is possible. A belt transmission can be realized.

  Next, the manufacturing method of the flat belt B of embodiment is demonstrated based on FIGS.

  In the production of the flat belt B of the embodiment, first, various compounding agents are blended in the rubber component, and are kneaded by a kneader such as an open roll, kneader, Banbury mixer, and the resulting uncrosslinked rubber composition is calendered roll or the like. To form an uncrosslinked rubber sheet 11 ′ for the core wire holding layer 11. Similarly, uncrosslinked rubber sheets 12 ', 13', 14 'for the outer rubber layer 12, the inner inner rubber layer, and the inner surface rubber layer 14 are also produced.

  Here, CNT is blended in the uncrosslinked rubber sheet 14 'for the inner surface rubber layer 14. From the viewpoint of dispersing CNT in the rubber, the uncrosslinked rubber sheet 14' for the inner surface rubber layer 14 is prepared. In this case, it is preferable to use a master batch in which CNT is blended at a high concentration in the rubber component. A method for producing a masterbatch is disclosed in Japanese Patent No. 4149413. Specifically, in the first kneading, the rubber component and the CNT are put into a kneader, and the first kneading temperature is set to 0 to 50 ° C. to perform preliminary kneading. In the second kneading, the obtained kneaded product is put into another kneader and kneaded at a second kneading temperature of 50 to 150 ° C. At this stage, polymer molecules of the rubber component are cleaved to generate radicals, and the wettability between the CNT and the rubber component is enhanced. In the third kneading, the obtained kneaded material is put into an open roll, and the third kneading temperature, that is, the roll temperature is set to 0 to 50 ° C., and is passed through a roll gap of 0.5 mm or less (thin). Thus, a master batch in which the CNTs are opened and dispersed in the rubber component is obtained. The kneader used in the first and second kneading may be an open roll, or a closed kneader such as a kneader or a Banbury mixer.

  Further, an adhesive treatment is performed in which the twisted yarn 15 ′ to be the core wire 15 is immersed in an RFL aqueous solution and heated, and if necessary, an adhesive treatment is performed in which the twisted yarn 15 ′ is immersed in rubber paste and dried by heating.

  Next, as shown in FIG. 5A, an uncrosslinked rubber sheet 12 ′ for the outer rubber layer 12 is wound around the outer periphery of the cylindrical mold 41, and then an uncrosslinked rubber sheet for the core wire holding layer 11 is wound thereon. Wrap 11 '. At this time, when short fibers are blended in the uncrosslinked rubber sheet 11 ′ for the core wire holding layer 11, the orientation direction of the uncrosslinked rubber sheet 11 ′, that is, the orientation direction of the short fibers is defined as a cylindrical mold. It is made to correspond to 41 axial directions. As a result, the manufactured flat belt B includes short fibers in which the core wire holding layer 11 is oriented in the belt width direction.

  Next, as shown in FIG. 5 (b), a twisted yarn 15 ′ that becomes the core wire 15 is spirally wound on the uncrosslinked rubber sheet 11 ′ for the core wire holding layer 11, and then the core is again formed thereon. An uncrosslinked rubber sheet 11 ′ for the line holding layer 11 is wound. When short fibers are blended in the uncrosslinked rubber sheet 11 ′ for the core wire holding layer 11, the row direction of the uncrosslinked rubber sheet 11 ′ is the axial direction of the cylindrical mold 41 as described above. Match.

  Next, as shown in FIG. 5 (c), an uncrosslinked rubber sheet 13 ′ for the inner intermediate rubber layer 13 is wound on the uncrosslinked rubber sheet 11 ′ for the core wire holding layer 11, and then the inner side is formed thereon. An uncrosslinked rubber sheet 14 ′ for the surface rubber layer 14 is wound to form a molded body B ′ on the cylindrical mold 41. At this time, when short fibers are blended in the uncrosslinked rubber sheet 13 ′ for the inner intermediate rubber layer 13, the orientation direction of the uncrosslinked rubber sheet 13 ′, that is, the orientation direction of the short fibers is defined as a cylindrical mold. It is made to correspond to 41 axial directions. Accordingly, the manufactured flat belt B includes short fibers in which the inner intermediate rubber layer 13 is oriented in the belt width direction. When short fibers are also blended in the uncrosslinked rubber sheet 14 'for the inner surface rubber layer 14 blended with CNTs, the orientation direction of the uncrosslinked rubber sheet 14', that is, the orientation direction of the short fibers is cylindrical. It matches with the axial direction of the mold 41. Thus, the manufactured flat belt B includes short fibers in which the inner surface rubber layer 14 is oriented in the belt width direction. When the short fiber is not blended in the uncrosslinked rubber sheet 14 'for the inner surface rubber layer 14, the uncrosslinked rubber sheet 14' for the inner surface rubber layer 14 blended with CNT is cylindrical in the line direction. Either the axial direction of the mold 41 or the circumferential direction of the cylindrical mold 41 may be used, but the latter is preferable.

  Subsequently, as shown in FIG. 6, the molded body B ′ on the cylindrical mold 41 is covered with a rubber sleeve 42, which is then set in a vulcanizing can and sealed, and the cylindrical mold 41 is heated with high-temperature steam or the like. And the rubber sleeve 42 is pressed in the radial direction on the cylindrical mold 41 side by applying a high pressure. At this time, the uncrosslinked rubber composition of the molded body B ′ flows, and the crosslinking reaction of the rubber component proceeds. In addition, the adhesion reaction of the twisted yarn 15 ′ to the rubber also proceeds, and as shown in FIG. A cylindrical belt slab S is formed on the cylindrical mold 41.

  And after taking out the cylindrical metal mold | die 41 from a vulcanization can and demolding the cylindrical belt slab S formed on the cylindrical metal mold | die 41, the outer peripheral surface and inner peripheral surface are grind | polished, and inner and outer thickness Make the thickness uniform.

  Finally, the flat belt B is obtained by cutting the belt slab S into a predetermined width and making each front and back opposite.

  In the above embodiment, the inner surface rubber layer 14 is formed of a rubber composition containing CNTs different from the rubber composition forming the core wire holding layer 11, the outer rubber layer 12, and the inner intermediate rubber layer 13. However, the present invention is not particularly limited thereto. For example, as shown in FIG. 8A, a rubber composition in which the inner intermediate rubber layer 13 and the inner surface rubber layer 14 are compounded with the same CNT. Therefore, the flat belt main body 10 is laminated in three layers: an outer rubber layer 12, a core wire holding layer 11, an inner intermediate rubber layer 13, and an inner rubber layer 16 integrally formed with an inner surface rubber layer 14. As shown in FIG. 8B, the rubber composition in which the core wire holding layer 11, the inner intermediate rubber layer 13, and the inner surface rubber layer 14 are blended with the same CNT, as shown in FIG. Therefore, the flat belt body 10 , The outer rubber layer 12 and the cord retaining layer 11, inner intermediate rubber layer 13 and inner surface rubber layer 14, may have a two-layer structure of the integrated rubber layer 16 which is formed integrally.

  In the above-described embodiment, the outer rubber layer 12 is provided on the outermost layer. However, the present invention is not particularly limited to this, and as shown in FIG. 17 may be provided, or, as illustrated in FIG. 9B, a configuration in which a reinforcing cloth 17 is provided instead of the outer rubber layer 12 may be used. In the case of providing a reinforcing cloth, a woven cloth or a knitted cloth that has been subjected to an adhesive treatment with an RFL aqueous solution and / or rubber paste at the time of manufacturing the flat belt B may be used.

(Master Badge)
The following first to seventh master batches were prepared. Each configuration is also shown in Table 1.

  Rubber-A (EPDM manufactured by Dow Chemical, trade name: Nordel IP 4640) and 60 parts by weight of CNT-A (MWCNT manufactured by Hodogaya Chemical Co., Ltd., trade name: NT-7B, average diameter 67 nm) with respect to 100 parts by weight of rubber-A Was put in an open roll, and the roll was cooled and passed through a 3 mm roll gap for preliminary kneading. Next, the roll temperature was set to 110 ° C., and the mixture was passed through a 2 mm roll gap for about 10 minutes. The roll was cooled and passed through a 0.5 mm roll gap 10 times to prepare a first master batch.

  Similarly, a second masterbatch is prepared from 50 parts by mass of CNT-B (Bayer MaterialScience MWCNT product name: Bytubes C70-P, diameter 13 to 16 nm) with respect to 100 parts by mass of rubber-A and rubber-A. did.

  A third masterbatch was prepared from 40 parts by mass of CNT-C (trade name: NC-7000, diameter 9.7 nm, manufactured by Nanocyl SA) with respect to 100 parts by mass of rubber-A and rubber-A.

  A fourth masterbatch was prepared from 5 parts by mass of CNT-D (Zeon Corporation SWCNT, diameter 3 nm) with respect to 100 parts by mass of rubber-A and rubber-A.

  A fifth masterbatch was prepared from rubber-B (EBM product name: Enage ENR7380 manufactured by Dow Chemical Co.) and 50 parts by mass of CNT-B with respect to 100 parts by mass of rubber-B.

  A sixth masterbatch was prepared from rubber-C (EOM product name: Engage 8180 manufactured by Dow Chemical) and 50 parts by mass of CNT-B with respect to 100 parts by mass of rubber-C.

  A seventh masterbatch was prepared from Rubber-D (H-NBR product name: Zetpol 2010L manufactured by Nippon Zeon Co., Ltd.) and 50 parts by mass of CNT-B with respect to 100 parts by mass of Rubber-D.

(Rubber composition)
The following rubber compositions 1-18 were prepared. Each configuration is also shown in Table 2.

<Rubber composition 1>
Using the first masterbatch, rubber-A as a rubber component, 20 parts by mass of CNT-A, 60 parts by mass of carbon black (FEF product name: Seast SO manufactured by Tokai Carbon Co., Ltd.) and process oil with respect to 100 parts by mass of rubber-A (Product name: Sunper 2280, manufactured by Sun Oil Co., Ltd.) 10 parts by weight, stearic acid as a processing aid (trade name: Stearic acid 50S, manufactured by Nippon Chemical Co., Ltd.), 1 part by weight of anti-aging agent-A Product name: NOCRACK MB) 2 parts by mass, zinc oxide as a vulcanization accelerator (made by Sakai Chemical Co., Ltd. product name: 3 types of zinc oxide), 5 parts by mass, organic peroxide as a crosslinking agent (manufactured by NOF Corporation) Product name: Parkmill D (dicumyl peroxide) 3 parts by mass and ethylene glycol dimethacrylate (trade name: Sunester EG) 3 parts by mass as co-crosslinking agent-A After being kneaded using a Banbury mixer which is a closed kneader, an uncrosslinked rubber composition 1 formed into a sheet having a thickness of 0.6 to 1.0 mm by a calender roll was prepared.

  In rubber composition 1, the compounding amount of carbon black with respect to 100 parts by mass of rubber-A is three times the compounding amount of CNT-A with respect to 100 parts by mass of rubber-A. The total amount of CNT-A and carbon black is 80 parts by mass with respect to 100 parts by mass of rubber-A. The rubber hardness of the crosslinked rubber composition 1 measured by a type A durometer based on JIS K6253 was 82.

<Rubber composition 2>
Using the second masterbatch, rubber-A as a rubber component, the same as rubber composition 1 except that 10 parts by mass of CNT-B was blended instead of CNT-A with respect to 100 parts by mass of rubber-A Uncrosslinked rubber composition 2 was prepared.

  In rubber composition 2, the compounding amount of carbon black with respect to 100 parts by mass of rubber-A is 6 times the compounding amount of CNT-B with respect to 100 parts by mass of rubber-A. The total amount of CNT-B and carbon black is 70 parts by mass with respect to 100 parts by mass of rubber-A. The rubber hardness of the crosslinked rubber composition 2 was 83.

<Rubber composition 3>
Using the second masterbatch, rubber-A as a rubber component, and 5 parts by mass of para-aramid short fibers (trade name: Technora cut fiber CFH3050, fiber length 3 mm, manufactured by Teijin Ltd.) with respect to 100 parts by mass of rubber-A An uncrosslinked rubber composition 3 similar to the rubber composition 2 was prepared except that it was blended.

  In the rubber composition 3, the compounding amount of carbon black with respect to 100 parts by mass of rubber-A is 6 times the compounding amount of CNT-B with respect to 100 parts by mass of rubber-A. The total amount of CNT-B and carbon black is 70 parts by mass with respect to 100 parts by mass of rubber-A. The rubber hardness of the crosslinked rubber composition 3 was 88.

<Rubber composition 4>
Using the third masterbatch, rubber-A as a rubber component, and similar to rubber composition 1 except that 5 parts by mass of CNT-C was blended instead of CNT-A with respect to 100 parts by mass of rubber-A. Uncrosslinked rubber composition 4 was prepared.

  In the rubber composition 4, the compounding amount of carbon black with respect to 100 parts by mass of rubber-A is 12 times the compounding amount of CNT-C with respect to 100 parts by mass of rubber-A. The total amount of CNT-C and carbon black is 65 parts by mass with respect to 100 parts by mass of rubber-A. The rubber hardness of the crosslinked rubber composition 4 was 82.

<Rubber composition 5>
Using the fourth masterbatch, rubber-A as a rubber component, the same as rubber composition 1 except that 5 parts by mass of CNT-D was blended instead of CNT-A with respect to 100 parts by mass of rubber-A. An uncrosslinked rubber composition 5 was prepared.

  In the rubber composition 5, the compounding amount of carbon black with respect to 100 parts by mass of rubber-A is 60 times the compounding amount with respect to 100 parts by mass of rubber-A of CNT-D. The total amount of CNT-D and carbon black is 61 parts by mass with respect to 100 parts by mass of rubber-A. The rubber hardness of the crosslinked rubber composition 5 was 83.

<Rubber composition 6>
Uncrosslinked rubber similar to rubber composition 2 except that the second masterbatch was used and carbon black was not blended, and the blending amount of CNT-B was 40 parts by weight with respect to 100 parts by weight of rubber-A. Composition 6 was prepared. The rubber hardness of the crosslinked rubber composition 6 was 84.

<Rubber composition 7>
Using the second masterbatch, rubber-A as the rubber component, and 100 parts by mass of rubber-A, instead of co-crosslinking agent-A, ethylene glycol dimethacrylate (manufactured by Sanshin Chemical Industry Co., Ltd.) as co-crosslinking agent-B Uncrosslinked rubber composition 7 was prepared in the same manner as rubber composition 2 except that 5 parts by mass of trade name: Sunester TMP) was blended.

  In the rubber composition 7, the compounding amount of carbon black with respect to 100 parts by mass of rubber-A is 6 times the compounding amount of CNT-B with respect to 100 parts by mass of rubber-A. The total amount of CNT-B and carbon black is 70 parts by mass with respect to 100 parts by mass of rubber-A. The rubber hardness of the crosslinked rubber composition 7 was 81.

<Rubber composition 8>
Using the second masterbatch, rubber-A is a rubber component, and N, N′-m-phenylenebismaleimide (co-crosslinking agent-C is used instead of co-crosslinking agent-A for 100 parts by mass of rubber-A ( An uncrosslinked rubber composition 8 similar to the rubber composition 2 was prepared except that 5 parts by mass of Sanshin Chemical Industry's trade name: Sanfell BM-G) was blended.

  In the rubber composition 8, the compounding amount of carbon black with respect to 100 parts by mass of rubber-A is 6 times the compounding amount of CNT-B with respect to 100 parts by mass of rubber-A. The total amount of CNT-B and carbon black is 70 parts by mass with respect to 100 parts by mass of rubber-A. The rubber hardness of the crosslinked rubber composition 8 was 82.

<Rubber composition 9>
Zinc methacrylate (made by Kawaguchi Chemical Industry Co., Ltd.) is used as a co-crosslinking agent-D instead of co-crosslinking agent-A with respect to 100 parts by mass of rubber-A without using CNT-A as a rubber component. An uncrosslinked rubber composition 9 similar to the rubber composition 1 was prepared except that 10 parts by mass of the trade name: Actor ZMA) was blended. The rubber hardness of the crosslinked rubber composition 9 was 85.

<Rubber composition 10>
Using rubber-A as a rubber component, and without adding CNT-A, 45 parts by mass of carbon black and 25 parts by mass of co-crosslinking agent-D instead of co-crosslinking agent-A with respect to 100 parts by mass of rubber-A An uncrosslinked rubber composition 10 similar to the rubber composition 1 except that it was blended was prepared. The rubber hardness of the crosslinked rubber composition 10 was 92.

<Rubber composition 11>
Using the fifth masterbatch, an uncrosslinked rubber composition 11 similar to the rubber composition 2 was prepared except that rubber-B was used as a rubber component.

  In the rubber composition 11, the compounding amount of carbon black with respect to 100 parts by mass of rubber-B is 6 times the compounding amount of CNT-B with respect to 100 parts by mass of rubber-B. The total amount of CNT-B and carbon black is 70 parts by mass with respect to 100 parts by mass of rubber-B. The rubber hardness of the crosslinked rubber composition 11 was 82.

<Rubber composition 12>
Using the sixth masterbatch, an uncrosslinked rubber composition 12 similar to the rubber composition 2 was prepared except that rubber-C was a rubber component.

  In the rubber composition 12, the compounding amount of carbon black with respect to 100 parts by mass of rubber-C is 6 times the compounding amount of CNT-B with respect to 100 parts by mass of rubber-C. The total amount of CNT-B and carbon black is 70 parts by mass with respect to 100 parts by mass of rubber-C. The rubber hardness of the crosslinked rubber composition 12 was 81.

<Rubber composition 13>
Uncrosslinked rubber composition similar to rubber composition 2 except that rubber-A is used as a rubber component and 90 parts by mass of carbon black is added to 100 parts by mass of rubber-A without compounding CNT-A. Product 13 was prepared. The rubber hardness of the crosslinked rubber composition 13 was 84.

<Rubber composition 14>
Using the seventh masterbatch, rubber D is used as a rubber component, 100 parts by weight of rubber D is mixed with 0.5 part by weight of anti-aging agent A, and DOS is used as a plasticizer instead of process oil. (Commercial name: Sunsizer DOS, manufactured by Shin Nippon Chemical Co., Ltd.) 5 parts by mass, and rubber composition except that 1 part by mass of anti-aging agent-B (trade name: Nocrack 224, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) An uncrosslinked rubber composition 14 similar to the product 2 was prepared.

  In the rubber composition 14, the compounding amount of carbon black with respect to 100 parts by mass of rubber-D is 6 times the compounding amount of CNT-B with respect to 100 parts by mass of rubber-D. The total amount of CNT-B and carbon black is 70 parts by mass with respect to 100 parts by mass of rubber-D. The rubber hardness of the crosslinked rubber composition 14 was 79.

<Rubber composition 15>
Uncrosslinked rubber similar to rubber composition 14 except that rubber-D is a rubber component, CNT-B is not blended, and the amount of carbon black is 90 parts by mass with respect to 100 parts by mass of rubber-D. Composition 15 was prepared. The rubber hardness of the crosslinked rubber composition 15 was 86.

<Rubber composition 16>
Rubber-D 30% by mass and Rubber-E (product name: Zeoforte ZSC 2295N (H-NBR / zinc methacrylate = 55/45)) 70% by mass blend rubber with rubber component and carbon black were blended. An uncrosslinked rubber composition 16 similar to the rubber composition 15 was prepared except that it was not. The rubber hardness of the crosslinked rubber composition 16 was 83.

<Rubber composition 17>
Rubber-A is used as a rubber component, CNT-A is not blended, and 100 parts by mass of rubber-A is further blended with 20 parts by mass of para-aramid short fibers. Rubber composition 17 was prepared. The rubber hardness of the crosslinked rubber composition 17 was 90.

<Rubber composition 18>
The rubber composition is the same as that of the rubber composition 16 except that a blend rubber of 20% by mass of rubber-D and 80% by mass of rubber-E is used as a rubber component and 10 parts by mass of para-aramid short fibers are further blended with 100 parts by mass of the rubber component. An uncrosslinked rubber composition 18 was prepared. The rubber hardness of the crosslinked rubber composition 18 was 96.

* 1: EPDM manufactured by Dow Chemical Company Name: Nordel IP 4640
* 2: EBM manufactured by Dow Chemical Co., Ltd. Trade name: Enage ENR7380
* 3: EOM manufactured by Dow Chemical Company Name: Engage 8180
* 4: H-NBR manufactured by Nippon Zeon Co., Ltd. Product name: Zetpol 2010L
* 5: Made by Nippon Zeon Co., Ltd. Product name: Zeoforte ZSC 2295N (H-NBR / zinc methacrylate = 50/50)
* 6: MWCNT manufactured by Hodogaya Chemical Co., Ltd. Product name: NT-7B, average diameter 67 nm
* 7: Bayer MaterialScience MWCNT Product name: Bytubes C70-P, diameter 13-16 nm
* 8: MWCNT manufactured by Nanocyl SA Product name: NC-7000, diameter 9.7 nm
* 9: SWCNT manufactured by Zeon Corporation, 3 nm in diameter
* 10: Carbon black FEF manufactured by Tokai Carbon Co., Ltd. Product name: Seast SO
* 11: Made by Sun Oil Co., Ltd. Product name: Thumper 2280
* 12: New Nippon Rika Co., Ltd. Product name: Sunsizer DOS
* 13: New Nippon Rika Co., Ltd. Brand name: Stearic acid 50S
* 14: Ouchi Shinsei Chemical Co., Ltd. Product name: NOCRACK MB
* 15: Ouchi Shinsei Chemical Co., Ltd. Product name: NOCRACK 224
* 16: 3 types of zinc oxide manufactured by Sakai Chemical Industry Co., Ltd.
* 17: Nippon Oil & Fats, Inc. Brand name: Park Mill D (Dicumyl Peroxide)
* 18: Sanshin Chemical Co., Ltd. Product name: Sunester EG
* 19: Sanshin Chemical Co., Ltd. Product name: Sunester TMP
* 20: Sanshin Chemical Co., Ltd. Product name: Sanfell BM-G
* 21: Kawaguchi Chemical Co., Ltd. Product name: Actor ZMA
* 22: Tarajin Para-aramid short fiber Product name: Technora cut fiber CFH3050, fiber length 3 mm
(Flat belt)
The flat belts of Examples 1 to 11 and Comparative Examples 1 to 5 below were produced. Each configuration is also shown in Table 3.

<Example 1>
The inner surface rubber layer is formed of the rubber composition 1, and the core wire holding layer, the outer rubber layer, and the inner intermediate rubber layer are formed of the rubber composition 17, and the core wire is subjected to an adhesion treatment with an RFL aqueous solution and rubber paste. A flat belt formed of a twisted yarn having an outer diameter of 0.7 mm of para-aramid fiber (trade name: Technora manufactured by Teijin Ltd.) was produced by the same method as in the above embodiment, and this was designated as Example 1. The core wire holding layer, the outer rubber layer, and the inner intermediate rubber layer were prepared so that the short fibers were oriented in the belt width direction.

  In the flat belt of this Example 1, the rubber composition 1 forming the inner surface rubber layer contains rubber-A as a rubber component, and CNT-A having a diameter of 70 nm, carbon black, and a co-crosslinking agent-A are blended. Yes.

  The belt circumference of the flat belt of Example 1 was 650 mm, the belt width was 20 mm, and the belt thickness was 3.0 mm. The thickness of the inner surface rubber layer was 0.6 mm.

<Example 2>
A flat belt having the same configuration as in Example 1 except that the inner surface rubber layer was formed of the rubber composition 2 was produced.

  In the flat belt of Example 2, the rubber composition 2 forming the inner surface rubber layer is composed of rubber-A as a rubber component, CNT-B having a diameter of 13 to 16 nm, carbon black, and a co-crosslinking agent-A. Has been.

<Example 3>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 3 was produced. The inner surface rubber layer was prepared so that the short fibers were oriented in the belt width direction.

  In the flat belt of this Example 3, the rubber composition 3 forming the inner surface rubber layer is composed of rubber-A as a rubber component, CNT-B having a diameter of 13 to 16 nm, carbon black, and a co-crosslinking agent-A. In addition, para-aramid short fibers oriented in the belt width direction are blended.

<Example 4>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 4 was produced.

  In the flat belt of Example 4, the rubber composition 4 forming the inner surface rubber layer contains rubber-A as a rubber component, and CNT-C having a diameter of 9.7 nm, carbon black, and a co-crosslinking agent-A. Has been.

<Example 5>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 5 was produced.

  In the flat belt of Example 5, the rubber composition 5 forming the inner surface rubber layer contains rubber-A as a rubber component, and CNT-D having a diameter of 3 nm, carbon black, and a co-crosslinking agent-A are blended. Yes.

<Example 6>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 6 was produced.

  In the flat belt of this Example 6, the rubber composition 6 forming the inner surface rubber layer contains rubber-A as a rubber component and CNT-B and co-crosslinking agent-A, but carbon black is blended. It has not been.

<Example 7>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 7 was produced.

  In the flat belt of Example 7, the rubber composition 7 forming the inner surface rubber layer contains rubber-A as a rubber component, and CNT-B, carbon black, and a co-crosslinking agent-B are blended.

<Example 8>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 8 was produced.

  In the flat belt of Example 8, the rubber composition 8 forming the inner surface rubber layer contains rubber-A as a rubber component and CNT-B, carbon black, and a co-crosslinking agent-C.

<Example 9>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 11 was produced.

  In the flat belt of Example 9, the rubber composition 11 forming the inner surface rubber layer contains rubber-B as a rubber component, and CNT-B, carbon black, and a co-crosslinking agent-A are blended.

<Example 10>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 12 was produced.

  In the flat belt of this Example 10, the rubber composition 12 forming the inner surface rubber layer contains rubber-C as a rubber component, and CNT-B, carbon black, and a co-crosslinking agent-A are blended.

<Example 11>
A flat surface having the same structure as in Example 1 except that the inner surface rubber layer is formed of the rubber composition 14 and the core wire holding layer, the outer rubber layer, and the inner intermediate rubber layer are formed of the rubber composition 18. A belt was prepared and used as Example 11.

  In the flat belt of Example 11, the rubber composition 14 forming the inner surface rubber layer contains rubber-D as a rubber component, and CNT-B, carbon black, and a co-crosslinking agent-A are blended.

<Comparative Example 1>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 9 was produced.

  In the flat belt of Comparative Example 1, the rubber composition 9 forming the inner surface rubber layer has rubber-A as a rubber component, carbon black and a co-crosslinking agent-D (zinc methacrylate) are blended, and has a high elastic modulus. However, CNT is not blended.

<Comparative example 2>
A flat belt having the same configuration as that of Example 1 except that the inner surface rubber layer was formed of the rubber composition 10 was produced.

  In the flat belt of this comparative example 2, the rubber composition 10 forming the inner surface rubber layer has rubber-A as a rubber component, carbon black and a co-crosslinking agent-D (zinc methacrylate) are blended, and has a high elastic modulus. However, CNT is not blended.

<Comparative Example 3>
A flat belt having the same configuration as in Example 1 except that the inner surface rubber layer was formed of the rubber composition 13 was produced, and this was designated as Comparative Example 3.

  In the flat belt of Comparative Example 3, the rubber composition 13 forming the inner surface rubber layer has rubber-A as a rubber component, and a large amount of carbon black and a co-crosslinking agent-A are blended to increase the elastic modulus. However, CNT is not blended.

<Comparative Example 4>
A flat surface having the same structure as in Example 1 except that the inner surface rubber layer is formed of the rubber composition 15 and the core wire holding layer, the outer rubber layer, and the inner intermediate rubber layer are formed of the rubber composition 18. A belt was produced and used as Comparative Example 4.

  In the flat belt of Comparative Example 4, the rubber composition 15 forming the inner surface rubber layer is made of rubber-D as a rubber component, and a large amount of carbon black and co-crosslinking agent-A are blended to increase the elastic modulus. However, CNT is not blended.

<Comparative Example 5>
A flat surface having the same structure as in Example 1 except that the inner surface rubber layer is formed of the rubber composition 16 and the core wire holding layer, the outer rubber layer, and the inner intermediate rubber layer are formed of the rubber composition 18. A belt was produced and used as Comparative Example 5.

  In the flat belt of this comparative example 5, the rubber composition 16 forming the inner surface rubber layer has a rubber component of a rubber blend of rubber-D and rubber-E, and has a high elastic modulus due to a large amount of zinc methacrylate in the rubber component. However, CNT and carbon black are not blended.

(Test evaluation method)
<Apparent friction coefficient μ 'on inner surface of belt>
For each of the flat belts of Examples 1 to 11 and Comparative Examples 1 to 5, a flat belt piece 21 having a length of 250 mm was cut out and wound on a flat pulley 22 having an outer diameter of 75 mm as shown in FIG. Wrapped at a hooking angle of 90 °, the upper end of the flat belt piece 21 is chucked and connected to the load cell 23, the lower end hanging vertically is chucked and the weight 24 is attached, The flat pulley 22 is rotated at a peripheral speed of 20 m / s so as to increase the tension of the portion from the load cell 23 to the flat pulley 22 of the belt piece 21, and the loose side tension Ts (= 19.6 N) by the weight 24 at that time From the tension side tension Tt detected by the load cell 23, the apparent friction coefficient μ ′ of the inner peripheral surface of the belt was obtained by the above equation (1) based on the Euler equation.

<Belt running test>
FIG. 10 shows a belt running test machine 50.

  This belt running test machine 50 includes a driving pulley 51 of a flat pulley having an outer diameter of 100 mm and a driven pulley 52 of a flat pulley having an outer diameter of 100 mm provided on the left side thereof. The drive pulley 51 is movably provided to the left and right so that the dead weight DW can be loaded on the flat belt B.

  About each flat belt B of Examples 1-11 and Comparative Examples 1-5, it wraps between the driving pulley 51 and the driven pulley 52 of this belt running test machine 50, and a shaft of 500 N is placed on the right side of the driving pulley 51. A load (dead weight DW) is applied to apply tension to the flat belt B, and the driven pulley 52 is rotated at 2000 rpm under an ambient temperature of 100 ° C. with a rotational torque of 12 N · m applied to the driven pulley 52. Rotated by number. And the running time until the slip of the flat belt B occurred was measured. If slip did not occur even after 300 hours, traveling was stopped at that time.

  Further, when 20 hours had elapsed from the start of running, the running was temporarily stopped, and the wear state of the inner surface rubber layer was confirmed. When the change in thickness is 30 μm or less and there is almost no wear, A, when the change in thickness is greater than 30 μm and 80 μm or less, B when the wear is small, and the change in thickness exceeds 80 μm. Cases were evaluated as C, respectively.

(Test evaluation results)
Table 4 shows the test evaluation results.

  The apparent friction coefficient μ ′ of the inner peripheral surface of the belt is 0.64 in Example 1, 0.73 in Example 2, 0.60 in Example 3, 0.67 in Example 4, and 0 in Example 5. .65, Example 6 is 0.70, Example 7 is 0.67, Example 8 is 0.65, Example 9 is 0.74, Example 10 is 0.76, and Example 11 is 0.00. 81, Comparative Example 1 was 0.63, Comparative Example 2 was 0.60, Comparative Example 3 was 0.63, Comparative Example 4 was 0.73, and Comparative Example 5 was 0.71.

  The running time until the occurrence of slip exceeded 300 hours in any of Examples 1 to 11, but no slip occurred, whereas Comparative Example 1 was 73 hours, Comparative Example 2 was 54 hours, and Comparative Example 3 was It was 138 hours, 170 hours for Comparative Example 4, and 46 hours for Comparative Example 5.

  The wear state at 20 hours of travel is B in Example 1, B in Example 2, A in Example 3, B in Example 4, B in Example 5, A in Example 6, and B in Example 7. Example 8 is B, Example 9 is B, Example 10 is B, Example 11 is A, and Comparative Example 1 is B, Comparative Example 2 is B, Comparative Example 3 is C, and Comparative Example 4 is B , And Comparative Example 5 was B.

  According to the above results, the flat belts of Examples 1 to 11 in which the rubber composition for forming the inner surface rubber layer was blended with CNT to increase the elastic modulus all slipped even during a long run exceeding 300 hours. It turns out that it runs stably without waking up. On the other hand, the flat belts of Comparative Examples 3 and 4 in which a large amount of carbon black was blended in the rubber composition forming the inner surface rubber layer to increase the elastic modulus caused slippage during running for several hundreds of hours. . Further, Comparative Examples 1, 2, and 5 in which the rubber composition forming the inner surface rubber layer was blended with zinc methacrylate to increase the elastic modulus caused slipping at a considerably early stage from the start of running. When a large amount of carbon black is blended, the time until slip is generated is longer than when zinc methacrylate is blended, but EPDM blended with a large amount of carbon black is inferior in wear resistance.

  The flat belt formed of a rubber composition in which the inner surface rubber layer is blended with CNTs can run stably for a long time without causing a slip, the friction coefficient of the surface, that is, the inner peripheral surface of the belt is stable. That's what it means. And such a stable friction coefficient is considered to originate in the cellulosic structure formed in the rubber composition which mix | blended CNT. The celllation structure is a structure like a biological cell in which rubber molecules are encapsulated in CNTs, and is considered to be a structure in which rubber molecules are confined in the nanospace of CNTs. If the reduction of the friction coefficient of the inner peripheral surface of the belt is caused by the hardening of the inner peripheral surface of the belt due to the oxidative degradation of the polymer molecules of the rubber component in the rubber composition forming the inner surface rubber layer, this cellulosic structure As a result, the polymer molecules are stabilized, and as a result, the decrease in the friction coefficient of the inner peripheral surface of the belt is considered to be suppressed. Even in a system in which carbon black and CNT coexist, it seems that a partial nanospace is formed.

  From the above, the flat belt in which CNT is blended with the rubber composition forming the inner surface rubber layer is excellent in stability of the friction coefficient of the inner peripheral surface of the belt, and therefore does not cause slippage even when running for a long time. You can expect. Therefore, in setting the initial tension of the flat belt, it is not necessary to consider a safety factor in anticipation of a decrease in the coefficient of friction. Therefore, transmission at a low tension is possible, and traveling loss can be reduced. Therefore, transmission of low energy consumption is also possible. Furthermore, since it is not necessary to reset the tension applied to the flat belt, it is possible to provide a maintenance-free transmission system.

  The present invention is useful for flat belts.

B flat belt B 'molded body S belt slab 10 flat belt body 11 core wire holding layer 11', 12 ', 13', 14 'uncrosslinked rubber sheet 12 outer rubber layer 13 inner intermediate rubber layer 14 inner surface rubber layer 15 core Wire 15 'Twisted thread 16 Integral rubber layer 17 Reinforcement cloth 21 Flat belt piece 22 Flat pulley 23 Load cell 24 Weight 30 Belt drive 31, 32, 33 Flat pulley 41 Cylindrical die 42 Rubber sleeve 50 Belt running test machine
51 Driving pulley 52 Driven pulley

Claims (5)

  A flat belt in which a portion constituting the inner peripheral surface of a belt is formed of a rubber composition containing carbon nanotubes. The flat belt according to claim 1,
A flat belt having a rubber hardness of 80 or more and less than 95 as measured by a type A durometer based on JIS K6253 of a rubber composition forming a portion constituting the inner peripheral surface of the belt. In the flat belt according to claim 1 or 2,
A flat belt having an apparent friction coefficient of 0.6 or more on the inner peripheral surface of the belt. In the flat belt according to any one of claims 1 to 3,
A flat belt in which carbon black is also blended in the rubber composition forming the portion constituting the inner peripheral surface of the belt. The flat belt according to any one of claims 1 to 4, wherein
A flat belt in which the metal composition of the α, β-unsaturated organic acid is not blended with the rubber composition forming the portion constituting the inner peripheral surface of the belt.

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