JP5060248B2 - Flat belt - Google Patents

Description

  The present invention relates to a core wire holding layer in which a core wire is embedded so as to form a spiral having a pitch in the belt width direction and having a pitch in the belt width direction, and a pulley contact portion provided on the inner peripheral side of the belt The present invention relates to a flat belt having an inner rubber layer.

  For the purpose of improving the durability of the transmission belt, the core wire holding layer in which the core wire is embedded and the inner or outer rubber layer are formed of rubber compositions having different elastic moduli.

  In Patent Document 1, a rubber layer having a higher elastic modulus than the core wire holding layer is provided outside the core wire holding layer, while a rubber layer having a lower elastic modulus than the core wire holding layer is provided inside the core wire holding layer. A V-belt provided with is disclosed.

  In Patent Document 2, the core wire holding layer is formed of a rubber composition in which short fibers oriented in the belt thickness direction are dispersed, and the inner tooth rubber layer is a rubber composition containing no short fibers. A formed toothed belt is disclosed.

  Patent Document 3 discloses a flat belt in which a short fiber mixed rubber layer is provided between a core wire holding layer and an inner rubber layer as a pulley contact portion provided on the inner peripheral side of the belt.

Patent Document 4 discloses a flat belt in which a reinforcing cloth is provided between a core holding layer of a thermoplastic resin and surface layers on both sides thereof.
Japanese Patent Laid-Open No. 61-286637 JP 2005-180486 A Japanese Utility Model Publication No. 6-47155 JP 2001-153186 A

  The flat belt does not exhibit a wedge effect on the pulley unlike the V-belt, and travels only by friction with the pulley, so that it is easy to meander and has low running stability. Therefore, as pulleys for flat belts, ones with flanges on both sides and crown-shaped ones with a smaller diameter from the center to the end are used, thereby suppressing meandering of the flat belt. Yes. For these reasons, flat belts have been mainly used for low-load conveyance applications and transmission applications.

  By the way, in recent years, a pulley capable of controlling the meandering of a flat belt has been developed, and accordingly, application of the flat belt to high load transmission is expected.

  However, if the conventional flat belt is directly applied to a high load transmission application, there is a problem in terms of durability.

  An object of the present invention is to provide a flat belt that exhibits excellent durability even in high load transmission applications.

The flat belt of the present invention that achieves the above object includes a core wire holding layer in which a core wire that extends in the belt length direction and is arranged to form a spiral having a pitch in the belt width direction is embedded, and the core An inner rubber layer that is a pulley contact portion provided on the belt inner peripheral side of the wire holding layer,
The core holding layer is formed of a rubber composition having a content of 1 to 20 parts by mass with respect to 100 parts by mass of the base rubber and containing short fibers dispersed and arranged so as to be oriented in the belt width direction. on the other hand,
The inner rubber layer is formed of a rubber composition not containing short fibers ,
Further, the core wire holding layer is provided with a twisted yarn that becomes the core wire on an unvulcanized rubber containing short fibers, on which another unvulcanized rubber containing short fibers is provided, and crosslinking of the unvulcanized rubber is characterized that you have been formed by the progress of the.

  In the flat belt of the present invention, the base rubber of the rubber composition forming the core wire holding layer may be an ethylene-α-olefin elastomer or a hydrogenated nitrile rubber.

  The flat belt of the present invention is suitable for a drive transmission use or a conveyance use of a blower, a compressor or a generator.

  According to the present invention, since the cord holding layer includes short fibers oriented in the belt width direction, shrinkage deformation in the belt width direction of the cord holding layer due to frictional heat during belt running is suppressed, thereby The core wire evenly distributes the load, and the rigidity in the belt width direction is increased without increasing the bending rigidity in the belt length direction, resulting in excellent durability even in high load transmission applications. it can. In addition, since the short rubber is not included in the inner rubber layer serving as the pulley contact portion, the friction coefficient of the surface is not reduced.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows a flat belt B according to the embodiment. This flat belt B is suitably used for high load transmission applications, and specific applications include, for example, drive transmission applications and conveying applications for blowers, compressors, and generators. The flat belt B can also be used for A-type, B-type and C-type V-belts defined in JIS K6323. Furthermore, it can also be used for friction transmission belts such as V-ribbed belts for automotive accessory driving. The flat belt B is formed, for example, with 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 is configured in a three-layer laminated structure including a core wire holding layer 11 constituting a belt intermediate layer, an inner rubber layer 12 on the belt inner peripheral side, and an outer rubber layer 13 on the belt outer peripheral side. Yes. A core wire 14 is embedded in the core wire holding layer 11 so as to form a spiral extending in the belt length direction and having a pitch in the belt width direction.

  The core wire holding layer 11 is formed in a band shape having a horizontally long cross section, and is formed to have a thickness of 0.3 to 1.0 mm, for example. The core wire holding layer 11 is formed of a rubber composition in which an unvulcanized rubber composition obtained by mixing and kneading a compounding agent with a base rubber is heated and pressurized and crosslinked with a crosslinking agent.

  Examples of the base rubber of the rubber composition forming the core wire holding layer 11 include ethylene-α-olefin elastomers such as ethylene / propylene rubber (EPR) and ethylene propylene diene monomer rubber (EPDM), chloroprene rubber (CR), Examples include chlorosulfonated polyethylene rubber (CSM) and hydrogenated nitrile rubber (H-NBR). Among these, the base rubber is preferably an ethylene-α-olefin elastomer or a hydrogenated nitrile rubber from the viewpoint of heat resistance of the rubber.

  Examples of the compounding agent blended in the rubber composition forming the core wire holding layer 11 include a crosslinking agent, a crosslinking aid, a vulcanization accelerator, an anti-aging agent, a reinforcing agent, a filler, a reinforcing agent, a plasticizer, Examples include processing aids, stabilizers, colorants, and the like. In addition, about each compounding agent, even if comprised by single type and may be comprised by multiple types, either may be sufficient.

  Examples of the crosslinking agent include organic peroxides and sulfur.

  Examples of the organic peroxide include dialkyl peroxides such as dicumyl peroxide, peroxyesters such as t-butylperoxyacetate, and ketone peroxides such as dicyclohexanone peroxide. The content of the organic peroxide is preferably 0.5 to 30 parts by mass and more preferably 1 to 15 parts by mass with respect to 100 parts by mass of the base rubber. When an organic peroxide is used as the crosslinking agent, a crosslinking assistant may be further blended. Examples of the crosslinking aid include triallyl isocyanurate (TAIC). The crosslinking aid may be composed of a single species or a plurality of species.

  The sulfur content is preferably 0.2 to 3.5 parts by mass and more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the base rubber. When using sulfur as a crosslinking agent, a crosslinking accelerator may be further blended. Examples of the crosslinking accelerator include N-oxydiethylenebenzothiazole-2-sulfenamide (OBS). The crosslinking accelerator may be composed of a single species or a plurality of species.

  Examples of the anti-aging agent include amine-based anti-aging agents and phenol-based anti-aging agents. The content of the anti-aging agent is preferably 0.1 to 5 parts by mass and more preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the base rubber.

  Examples of the reinforcing agent include carbon black such as furnace black and thermal black. It is preferable that content of a reinforcing agent is 20-100 mass parts with respect to 100 mass parts of base rubbers, and it is more preferable that it is 40-80 mass parts.

  Examples of the filler include calcium carbonate, talc, diatomaceous earth, and the like. The content of the filler is preferably 5 to 50 parts by mass and more preferably 5 to 30 parts by mass with respect to 100 parts by mass of the base rubber.

  Silica etc. are mentioned as an enhancer. The content of the enhancer is preferably 5 to 80 parts by mass and more preferably 5 to 60 parts by mass with respect to 100 parts by mass of the base rubber.

  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 content of the plasticizer is preferably 0.1 to 40 parts by mass, and more preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the base rubber.

  Examples of the processing aid include paraffinic oil, naphthenic oil, and aromatic oil. The content of the processing aid is preferably 0.1 to 40 parts by mass, and more preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the base rubber.

  The rubber composition for forming the core wire holding layer 11 includes short fibers 15 dispersed and arranged so as to be oriented in the belt width direction.

  Examples of the short fibers 15 include nylon 6 short fibers, nylon 66 short fibers, polyester short fibers, cotton short fibers, and aramid short fibers. The short fibers 15 may be composed of a single species or a plurality of species.

  Content of the short fiber 15 is 1-20 mass parts with respect to 100 mass parts of base rubbers, and it is more preferable that it is 1-10 mass parts.

  The fiber length of the short fibers 15 is preferably 0.1 to 5 mm, and more preferably 0.5 to 3 mm.

  The tensile elastic modulus of the short fiber 15 is preferably 1 to 800 CN / dtex, and more preferably 20 to 600 CN / dtex. The tensile elastic modulus can be measured according to JIS L 1013 for the filament yarn before cutting.

  The short fibers 15 may be either subjected to a so-called adhesion treatment on the surface or not. Examples of the adhesion treatment include a treatment of heating after immersion in a resorcin / formalin / latex aqueous solution (hereinafter referred to as “RFL aqueous solution”) and the like, and a treatment of dipping in rubber paste and drying.

  The inner rubber layer 12 is configured in a strip shape having a horizontally long cross section, and is formed to have a thickness of 0.5 to 1.5 mm, for example. The inner rubber layer 12 is formed of a rubber composition in which an unvulcanized rubber composition obtained by blending a compounding agent with a base rubber and kneaded is heated and pressurized and crosslinked with a crosslinking agent. This inner rubber layer 12 constitutes a pulley contact portion.

  Examples of the base rubber of the rubber composition forming the inner rubber layer 12 include the same rubber as that forming the core wire holding layer 11.

  As a compounding agent mix | blended with the rubber composition which forms the inner side rubber layer 12, the same thing as what forms the said core wire holding | maintenance layer 11 is mentioned.

  The rubber composition forming the inner rubber layer 12 does not contain the short fibers 15.

  The outer rubber layer 13 is formed in a band shape having a horizontally long cross section, and is formed to have a thickness of 0.5 to 1.5 mm, for example. The outer rubber layer 13 is formed of a rubber composition in which an unvulcanized rubber composition obtained by blending a compounding agent with a base rubber and kneaded is heated and pressurized and crosslinked with a crosslinking agent. This outer rubber layer 13 constitutes the belt back surface portion.

  Examples of the base rubber of the rubber composition that forms the outer rubber layer 13 include the same rubbers that form the core wire holding layer 11.

  As a compounding agent mix | blended with the rubber composition which forms the outer side rubber layer 13, the same thing as what forms the said core wire holding | maintenance layer 11 is mentioned.

  The rubber composition forming the outer rubber layer 13 may contain either short fibers or no short fibers.

  When the short fiber is contained in the rubber composition forming the outer rubber layer 13, the same fiber type as that contained in the core wire holding layer 11 may be mentioned as the fiber type. The content of the short fiber is preferably 1 to 20 parts by mass and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the base rubber. The fiber length of the short fibers is preferably 0.1 to 5 mm, and more preferably 0.5 to 3 mm. The tensile elastic modulus of the short fiber is preferably 1 to 800 CN / dtex, and more preferably 20 to 600 CN / dtex. The short fibers may be provided so as to be oriented in any of the belt width direction, the belt length direction, and the belt thickness direction, or may be provided non-oriented. The short fibers may or may not have been subjected to a so-called adhesion treatment on the surface.

  The core wire holding layer 11, the inner rubber layer 12, and the outer rubber layer 13 may be the same type of base rubber or may be different from each other.

  The core 14 is made of, for example, a polyester fiber such as polyethylene terephthalate fiber (PET) or polyethylene naphthalate fiber (PEN), and a twisted yarn such as aramid fiber or vinylon fiber. For example, the core wire 14 has an outer diameter of 0.1 to 2.0 mm. Even if the burying position of the core wire 14 in the core wire holding layer 11 is the center in the belt thickness direction or the side closer to the inner rubber layer 12 in the belt thickness direction, the belt thickness direction Even the side close to the outer rubber layer 13 may be used.

  The core wire 14 has been subjected to an adhesive treatment for heating after being immersed in an RFL aqueous solution before molding and / or an adhesive treatment for drying after being immersed in rubber paste in order to impart adhesion to the core wire holding layer 11. It is preferable that

  According to the flat belt B having the above-described configuration, since the core wire holding layer 11 includes the short fibers 15 oriented in the belt width direction, the core wire holding layer 11 is contracted and deformed in the belt width direction due to frictional heat during belt running. As a result, the core wire 15 is uniformly distributed in load, and the rigidity in the belt width direction is increased without increasing the bending rigidity in the belt length direction. High running stability and excellent durability can be obtained both in the application to be used and in the high load transmission application. And since the short fiber is not contained in the inner side rubber layer 12 which is a pulley contact part, the friction coefficient of the surface is not reduced.

  Next, a method for manufacturing the flat belt B will be described with reference to FIG.

  In the production of the flat belt B, a cylindrical mold and a rubber sleeve (both not shown) are used.

  First, an unvulcanized rubber sheet 13 ′ for forming the outer rubber layer 13 is wound around the outer periphery of the cylindrical mold, and then a sheet surface for forming the outer peripheral portion of the core wire holding layer 11 thereon. The unvulcanized rubber sheet 11a ′ including the short fibers 15 oriented in one direction is wound around. At this time, the orientation direction of the short fibers 15 is matched with the axial direction of the cylindrical mold.

  Next, a twisted yarn 14 ′ that becomes the core wire 14 is spirally wound thereon, and then the short yarn oriented in one direction within the sheet surface for forming the inner peripheral portion of the core wire holding layer 11 thereon. An unvulcanized rubber sheet 11b ′ containing the fibers 15 is wound. At this time, the orientation direction of the short fibers 15 is matched with the circumferential direction of the cylindrical mold. Further, an uncrosslinked rubber sheet 12 ′ for forming the inner rubber layer 12 is wound thereon.

  After that, cover the molded body of the cylindrical mold with a rubber sleeve and set it in the molding kettle, heat the cylindrical mold with high-temperature steam, etc., and apply a high pressure to bring the rubber sleeve inward in the radial direction. Press. At this time, the unvulcanized rubber composition flows and the crosslinking reaction proceeds. In addition, the adhesion reaction of the twisted yarn 14 ′ to the rubber also proceeds, thereby forming a cylindrical belt slab.

  Subsequently, after removing the cylindrical mold from the molding pot, the belt slab formed on the cylindrical mold is removed.

  Finally, by polishing the outer peripheral surface and inner peripheral surface of the belt slab to make the inner and outer thickness uniform, the belt slab is cut into a predetermined width, and the flat belt B obtain.

  In this embodiment, the flat belt B has a three-layer structure of the core wire holding layer 11, the inner rubber layer 12, and the outer rubber layer 13. However, the present invention is not limited to this, and the core wire of the present embodiment is not limited thereto. As long as it has the same configuration as the holding layer 11 and the inner rubber layer 12, it may have a two-layer structure or a structure with four or more layers.

  The evaluation test performed on the flat belt will be described.

(Composition of rubber composition)
<Rubber composition for core holding layer>
The following rubber compositions 1 to 14 were kneaded and adjusted as the rubber composition for the core wire holding layer. Details are also shown in Table 1.

-Rubber composition 1-
EPDM (ethylene propylene diene monomer rubber) (trade name: Nordel IP 4640, manufactured by The Dow Chemical Company), which is a base rubber, and carbon black FEF (trade name: Seast SO, manufactured by Tokai Carbon Co., Ltd.) with respect to 100 parts by mass of the base rubber. ) 70 parts by mass, 10 parts by mass of paraffinic oil (trade name: Samper 2280, manufactured by Nippon San Oil Co., Ltd.), 1 part by mass of stearic acid (trade name: stearic acid 50S, manufactured by Shin Nippon Chemical Co., Ltd.), zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.) Product name: 5 parts by mass of zinc oxide (3 types), cross-linking aid (trade name: Hi-Cross M, manufactured by Seiko Chemical Co., Ltd.) and 2 parts by mass of organic peroxide (product name: Park Mill D, manufactured by NOF Corporation) Para-aramid short fiber (trade name: Technora cut fiber CFH3050, manufactured by Teijin) A kneaded material consisting of 10 parts by mass (fiber length 3 mm) was put into a closed kneader and kneaded, and the resulting rubber composition was designated as rubber composition 1.

  This rubber composition 1 is rolled with a roll to form an unvulcanized rubber sheet, which is press-crosslinked at 160 ° C. for 30 minutes to obtain a sheet-like crosslinked rubber composition. This crosslinked rubber composition is JIS K 6253. When a durometer hardness test was conducted using a type A durometer according to the above, the hardness was 88.

-Rubber composition 2-
A kneaded material having the same structure as that of the rubber composition 1 except that the blending amount of the para-aramid short fibers is 1 part by mass is put into a closed kneader and kneaded, and the obtained rubber composition is rubber composition 2 It was. It was 81 when the hardness was measured similarly to the rubber composition 1.

-Rubber composition 3-
A kneaded material having the same structure as that of the rubber composition 1 except that the blend amount of the para-aramid short fibers is 2 parts by mass is put into a closed kneader and kneaded, and the resulting rubber composition is rubber composition 3 It was. When the hardness was measured in the same manner as rubber composition 1, it was 82.

-Rubber composition 4-
A kneaded material having the same structure as that of the rubber composition 1 except that the blending amount of the para-aramid short fibers is 5 parts by mass is put into a closed kneader and kneaded, and the obtained rubber composition is rubber composition 4 It was. It was 84 when the hardness was measured similarly to the rubber composition 1.

-Rubber composition 5-
A kneaded material having the same structure as that of the rubber composition 1 except that the blend amount of the para-aramid short fibers is 20 parts by mass is put into a closed kneader and kneaded, and the resulting rubber composition is the rubber composition 5. It was. It was 94 when hardness was measured similarly to the rubber composition 1.

-Rubber composition 6
A kneaded material having the same configuration as that of the rubber composition 1 except that 10 parts by mass of meta-aramid short fibers (trade name: Cornex cut fiber CFA3000, fiber length 3 mm) manufactured by Teijin is blended instead of the para-aramid short fibers. The resulting rubber composition was put into a machine and kneaded to obtain rubber composition 6. When the hardness was measured in the same manner as rubber composition 1, it was 86.

-Rubber composition 7-
A kneading material having the same configuration as that of the rubber composition 1 except that 10 parts by mass of vinylon short fibers (product name: CFV3010, fiber length: 3 mm) are blended in place of the para-aramid short fibers is put into a closed kneader. The rubber composition thus obtained was kneaded and used as rubber composition 7. It was 85 when the hardness was measured similarly to the rubber composition 1.

-Rubber composition 8-
A kneaded material having the same structure as that of the rubber composition 1 except that 10 parts by mass of cotton short fibers (trade name: denim chipper 5, fiber length 5 mm) manufactured by Hashimoto Co., Ltd. was blended instead of the para-aramid short fibers. The resulting rubber composition was put into a machine and kneaded to obtain rubber composition 8. When the hardness was measured in the same manner as rubber composition 1, it was 82.

-Rubber composition 9-
A kneading material having the same structure as that of the rubber composition 1 except that 10 parts by mass of nylon short fibers (product name: nylon 6,6, fiber length: 3 mm) manufactured by Asahi Kasei Co., Ltd. was blended instead of the para-aramid short fibers. The resulting rubber composition was put into a machine and kneaded to obtain rubber composition 9. It was 84 when the hardness was measured similarly to the rubber composition 1.

-Rubber composition 10-
A kneaded material having the same structure as that of the rubber composition 1 except that EBM (ethylene butene monomer rubber) (trade name: Enage ENR7380, manufactured by The Dow Chemical Company) is used as the base rubber instead of EPDM is used in a closed kneader. The rubber composition obtained by charging and kneading was used as rubber composition 10. It was 90 when hardness was measured similarly to the rubber composition 1.

-Rubber composition 11-
A kneaded material having the same structure as that of the rubber composition 1 except that EOM (ethylene octene monomer rubber) (trade name: Engage 8180, manufactured by The Dow Chemical Company) is used as the base rubber instead of EPDM is used in a closed kneader. The rubber composition obtained by charging and kneading was used as rubber composition 11. It was 92 when the hardness was measured similarly to the rubber composition 1.

-Rubber composition 12-
A kneaded material having the same structure as that of the rubber composition 1 except that H-NBR (hydrogenated nitrile rubber) (trade name: Zetpol 2010H, manufactured by Nippon Zeon Co., Ltd.) was used instead of EPDM as the base rubber. The rubber composition obtained by charging and kneading was used as rubber composition 12. When the hardness was measured in the same manner as rubber composition 1, it was 86.

-Rubber composition 13-
A kneaded material having the same structure as that of the rubber composition 1 except that no para-aramid short fibers were blended was put into a closed kneader and kneaded, and the resulting rubber composition was designated as a rubber composition 13. It was 79 when the hardness was measured similarly to the rubber composition 1.

-Rubber composition 14-
A kneaded material having the same structure as that of the rubber composition 1 except that the blend amount of the para-aramid short fibers is 25 parts by mass is put into a closed kneader and kneaded, and the resulting rubber composition is rubber composition 14 It was. It was 96 when hardness was measured similarly to the rubber composition 1.

<Rubber composition for inner and outer rubber layers>
The following rubber compositions 15 to 16 were kneaded and adjusted as rubbers for the inner rubber layer and the outer rubber layer. Details are shown in Table 1.

-Rubber composition 15-
As the rubber composition 15 for the inner and outer rubber layers, a kneaded material having the same structure as that of the rubber composition 1 except that no para-aramid short fibers were blended was put into a closed kneader and kneaded. It was 79 when the hardness was measured similarly to the rubber composition 1. The rubber composition 15 has the same configuration as the rubber composition 13 for the core wire holding layer.

-Rubber composition 16-
As the rubber composition 16 for the inner and outer rubber layers, a kneaded material having the same configuration as that of the rubber composition 1 except that the blend amount of the para-aramid short fibers is 15 parts by mass is put into a closed kneader and kneaded. did. It was 90 when hardness was measured similarly to the rubber composition 1.

(Flat belt for test evaluation)
The flat belts of Examples 1 to 12 and Comparative Examples 1 to 4 below were produced. Each configuration is also shown in Table 2.

<Example 1>
A flat belt in which the core wire holding layer was formed from the rubber composition 1 and the inner rubber layer and the outer rubber layer were formed from the rubber composition 15 was produced.

  The core wire holding layer was formed so that the short fibers were oriented in the belt width direction. The core wire was composed of aramid fiber (1100 dtex) twisted yarn, the belt peripheral length was 1100 mm, the belt width was 15 mm, and the belt thickness was 2.6 mm.

<Example 2>
A flat belt having the same configuration as in Example 1 was produced except that the core wire holding layer was formed with the rubber composition 2, and this was designated as Example 2.

<Example 3>
A flat belt having the same configuration as in Example 1 was produced except that the core wire holding layer was formed with the rubber composition 3 and this was designated as Example 3.

<Example 4>
A flat belt having the same configuration as that of Example 1 was prepared except that the core wire holding layer was formed of the rubber composition 4, and this was designated as Example 4.

<Example 5>
A flat belt having the same configuration as that of Example 1 was prepared except that the core wire holding layer was formed of the rubber composition 5, and this was designated as Example 5.

<Example 6>
A flat belt having the same configuration as in Example 1 was produced except that the core wire holding layer was formed of the rubber composition 6, and this was designated as Example 6.

<Example 7>
A flat belt having the same configuration as that of Example 1 was prepared except that the core wire holding layer was formed of the rubber composition 7, and this was designated as Example 7.

<Example 8>
A flat belt having the same configuration as that of Example 1 was prepared except that the core wire holding layer was formed of the rubber composition 8, and this was designated as Example 8.

<Example 9>
A flat belt having the same configuration as in Example 1 was produced except that the core wire holding layer was formed with the rubber composition 9, and this was designated as Example 9.

<Example 10>
A flat belt having the same configuration as in Example 1 was produced except that the core wire holding layer was formed of the rubber composition 10 and this was designated as Example 10.

<Example 11>
A flat belt having the same configuration as that of Example 1 was prepared except that the core wire holding layer was formed of the rubber composition 11, and this was designated as Example 11.

<Example 12>
A flat belt having the same configuration as in Example 1 was produced except that the core wire holding layer was formed of the rubber composition 12 and this was designated as Example 12.

<Comparative Example 1>
A flat belt having the same configuration as that of Example 1 was prepared except that the core wire holding layer was formed of the rubber composition 13, and this was designated as Comparative Example 1. This is a structure in which the entire core wire holding layer, inner rubber layer and outer rubber layer are formed of the same rubber composition.

<Comparative example 2>
A flat belt having the same configuration as that of Example 1 was prepared except that the orientation direction of the short fibers of the core wire holding layer was changed to the belt length direction.

<Comparative Example 3>
A flat belt having the same configuration as that of Example 1 was prepared except that the core wire holding layer was formed of the rubber composition 14, and this was designated as Comparative Example 3.

<Comparative example 4>
A flat belt having the same configuration as that of Example 1 except that the inner rubber layer and the outer rubber layer were formed with the rubber composition 15 was produced.

  The inner rubber layer and the outer rubber layer were formed so that the short fibers were oriented in the belt width direction.

(Test evaluation method)
FIG. 3 shows a pulley layout of the belt running test machine 30 used for the test evaluation.

  The belt running test machine 30 is arranged on the upper and lower flat pulleys having a diameter of 120 mm (the upper side is a driven pulley and the lower side is a driving pulley) 31 and 32, and the middle between them. And a small-sized flat pulley 33 having a pulley diameter of 75 mm. The small-diameter flat pulleys 33 are positioned so that the belt winding angle is 90 degrees inside the belt.

  For each of Examples 1 to 12 and Comparative Examples 1 to 4, it is wound around three flat pulleys 31, 32, 33, and a small-diameter flat pulley 33 is pulled to the side so that a dead weight of 392N is loaded. Under the atmospheric temperature of 120 ° C., the lower flat pulley 32 serving as a driving pulley was rotated clockwise at a rotational speed of 4900 rpm, and the time until the belt could not be run was measured as the belt durability running time.

  And the ratio of the running time with respect to the belt durable running time of the comparative example 1 was made into the parameter | index of belt durability. We also observed the cause of the failure that prevented the belt from running.

(Test evaluation results)
Table 2 shows the test evaluation results of Examples 1 to 12 and Comparative Examples 1 to 4. Table 3 shows the results of Examples 1 to 5, Comparative Example 1 and Comparative Example 3 that are different only in the content of short fibers.

  According to Table 2, Examples 1 to 12 in which the core wire holding layer was formed of a rubber composition containing short fibers, and Comparative Example 1 in which the core wire holding layer was formed of a rubber composition not containing short fibers, When comparing the above, it can be seen that the former is more durable than the latter.

  Example 1 in which a core wire holding layer was formed with a rubber composition containing short fibers dispersed so as to be oriented in the belt width direction, and dispersed so as to be oriented in the belt length direction When compared with Comparative Example 2 in which the core wire holding layer is formed of a rubber composition containing short fibers, it can be seen that the former is superior in durability to the latter.

  Examples 1 to 12 in which a core wire holding layer was formed of a rubber composition having a content of 1 to 20 parts by mass of the short fiber based on 100 parts by mass of the base rubber, and a content of the short fiber to 100 parts by mass of the base rubber Comparing with Comparative Example 3 in which the core wire holding layer is formed with a rubber composition of 25 parts by mass, it can be seen that the former is more durable than the latter.

  When comparing Example 1 in which inner and outer rubber layers were formed with a rubber composition not containing short fibers, and Comparative Example 4 in which inner and outer rubber layers were formed with a rubber composition containing short fibers, the former It can be seen that the durability is superior to the latter.

  Therefore, the core holding layer is formed of a rubber composition containing 1 to 20 parts by mass of short fibers with respect to 100 parts by mass of the base rubber, the orientation direction of which is the belt width direction, and the inner rubber layer and the outer By forming the rubber layer with a rubber composition that does not contain short fibers, excellent durability can be obtained.

  As described above, the present invention is useful for flat belts.

It is a perspective view which shows the structure of the flat belt concerning embodiment. It is explanatory drawing which shows the manufacturing method of a flat belt. It is a figure which shows the pulley layout of a belt test traveling machine.

Explanation of symbols

B flat belt 11 core wire holding layer 12 inner rubber layer 13 outer rubber layer 14 core wire 15 short fiber

Claims (8)

A core-holding layer in which a core wire extending so as to extend in the belt length direction and having a pitch in the belt width direction is embedded, and a pulley provided on the inner peripheral side of the core-wire holding layer A flat belt having an inner rubber layer as a contact portion,
The core holding layer is formed of a rubber composition having a content of 1 to 20 parts by mass with respect to 100 parts by mass of the base rubber and containing short fibers dispersed and arranged so as to be oriented in the belt width direction. on the other hand,
The inner rubber layer is formed of a rubber composition not containing short fibers ,
Further, the core wire holding layer is provided with a twisted yarn that becomes the core wire on an unvulcanized rubber containing short fibers, on which another unvulcanized rubber containing short fibers is provided, and flat belt crosslinking of the unvulcanized rubber is characterized that you have been formed in progress. The flat belt according to claim 1,
In the rubber composition forming the core wire holding layer, the base rubber is an ethylene-α-olefin elastomer or a hydrogenated nitrile rubber. In the flat belt according to claim 1 or 2,
A flat belt characterized in that it is used for a drive transmission application or a conveyance application of a blower, a compressor or a generator. In the flat belt according to any one of claims 1 to 3,
A flat belt, further comprising an outer rubber layer formed of a rubber composition which is provided on the outer peripheral side of the core holding layer and does not contain short fibers. The flat belt according to any one of claims 1 to 4, wherein
A flat belt, wherein the short fibers are para-aramid short fibers, meta-aramid short fibers, vinylon short fibers, cotton short fibers, or nylon short fibers. The flat belt according to any one of claims 1 to 5,
A flat belt characterized in that the short fiber has a fiber length of 0.1 to 5 mm. The flat belt according to any one of claims 1 to 6,
A flat belt, wherein the rubber composition forming the inner rubber layer is the same as the rubber composition forming the core wire holding layer except that it does not contain short fibers. The flat belt according to claim 4, wherein
A flat belt, wherein the rubber composition forming the outer rubber layer is the same as the rubber composition forming the core wire holding layer except that it does not contain short fibers.

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