Toothed belt

Abstract

To provide a toothed belt 10 that achieves reduced dust emission and is suitable for high load transmission.SOLUTION: A toothed belt 10 has: a belt body 11 having a back rubber part 11a and a plurality of tooth rubber parts 11b, with the back rubber part 11a and the tooth rubber parts 11b composed of a thermoplastic elastomer composition; a core wire 13 buried in an inner peripheral portion of the back rubber part 11a; a tooth part covering material 14 that covers the plurality of tooth rubber parts 11b; and a side member 22 that is laminated on an end face 11 s of the belt body 11 and forms a belt end face 10 s. The thermoplastic elastomer composition comprises an elastomer component that is TPAE or TPC. The thermoplastic elastomer composition constituting the back rubber part 11a has hardness of 25-70, and the thermoplastic elastomer composition constituting the tooth rubber part 11b has hardness of 40-70, which is equal to or greater than the hardness of the thermoplastic elastomer constituting the back rubber part 11a. The core wire 13 contains a carbon filament and is not exposed from the belt end face 10 s.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a toothed belt.

Background Art

[0002] Conventionally, as toothed belts, rubber belts and cast urethane belts are known. These belts all include a back rubber portion, a large number of tooth rubber portions integrally provided at a predetermined pitch in the longitudinal direction of the belt on this back rubber portion, and a core wire embedded so as to extend in the longitudinal direction of the belt and at a predetermined pitch in the width direction of the belt between the back rubber portion and the tooth rubber portion. The two differ in that the back rubber portion and the tooth rubber portion are formed of vulcanized rubber or cast urethane.

[0003] Since these belts require a vulcanization process and a post-vulcanization process in the manufacturing process, their productivity is low. Further, due to the nature of vulcanized rubber and cast urethane, these belts have problems in that post-treatment such as shape imparting after belt molding is difficult, and furthermore, recycling is difficult.

[0004] As a toothed belt capable of solving such problems, a toothed belt in which the back rubber portion and the tooth rubber portion are formed of a thermoplastic elastomer has been proposed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a toothed belt in which a thermoplastic elastomer is used for forming a back rubber portion and a tooth rubber portion, there has been a problem that when the load applied to the belt increases, the belt teeth are likely to deform. Further, when the rotational speed of the pulley with the belt increases, the belt generates heat, and in this case as well, there has been a problem that the belt teeth are likely to deform.

[0007] In Patent Document 2 described above, a single-twist yarn obtained by single-twisting filaments made of carbon fiber (hereinafter referred to as carbon filaments) is adopted as a core wire. Carbon fiber is less likely to deform due to creep compared to organic fiber. Therefore, by adopting a yarn made of carbon fiber as a core wire, the toothed belt can suppress a decrease in tension due to use. There is an expectation that this toothed belt can be used over a long period.

[0008] By the way, in the manufacture of a toothed belt, a cylindrical belt slab is produced. By cutting this belt slab into a predetermined width, a toothed belt is obtained. The belt end face of the toothed belt consists of a cut surface, and the core wire is exposed on this belt end face. Since fiber dust is generated from the exposed core wire and scatters, this toothed belt cannot be used in an environment where the air cleanliness is controlled, such as a clean room. Carbon fiber has conductivity. Therefore, for example, if fiber dust made of carbon fiber adheres to a circuit of electrical equipment, the circuit may short-circuit and the electrical equipment may malfunction. According to the extrusion manufacturing method, a toothed belt can be produced without exposing the core wire on the belt end face. However, in this manufacturing method, a belt of a predetermined length is formed, and the ends of this belt are connected to obtain a toothed belt. Therefore, even if high-strength carbon fiber is used for the core wire, this toothed belt cannot be used as a belt for power transmission that requires high-load transmission.

[0009] The present invention has been made in view of such circumstances, and an object thereof is to provide a toothed belt having low dust generation property and suitable for high-load transmission.

Means for Solving the Problems

[0010] (1) The toothed belt of the present invention has a flat belt-shaped back rubber part and a plurality of tooth rubber parts arranged on the inner peripheral side of the back rubber part and each integrally provided on the back rubber part to form belt teeth. The belt body is composed of a thermoplastic elastomer composition for both the back rubber part and the tooth rubber part, a core wire arranged and embedded so as to form a helix having a pitch in the belt width direction in a part on the inner peripheral side of the back rubber part, a tooth part covering material covering the plurality of tooth rubber parts provided on the inner peripheral side of the belt body, and a side member laminated on the end face of the belt body to form the belt end face. The elastomer component of the thermoplastic elastomer composition is a polyamide-based thermoplastic elastomer (TPAE) or a polyester-based thermoplastic elastomer (TPC). The hardness of the thermoplastic elastomer composition constituting the back rubber part is 25 to 70, the hardness of the thermoplastic elastomer composition constituting the tooth rubber part is 40 to 70, and is equal to or higher than the hardness of the thermoplastic elastomer composition constituting the back rubber part. The core wire includes carbon filaments made of carbon fiber and is not exposed on the belt end face.

[0011] In the above toothed belt, the back rubber part and the tooth rubber part are composed of a composition having a polyamide-based thermoplastic elastomer (TPAE) or a polyester-based thermoplastic elastomer (TPC) as an elastomer component. Therefore, in the manufacturing process, a vulcanization process or a post-vulcanization process is not required, and this toothed belt is excellent in productivity. Further, the above elastomer component is heat-resistant, and the decrease in the elastic modulus is small even at the heat generation temperature when the belt is driven at a high load or a high rotational speed. Therefore, deformation hardly occurs during belt driving, and defects such as tooth skipping caused by deformation of the tooth rubber part are unlikely to occur.

[0012] In the above toothed belt, the thermoplastic elastomer compositions constituting the back rubber part and the tooth rubber part each have a specific hardness. Therefore, it is possible to suppress the belt from being too soft and deforming when receiving power, resulting in chipping of the teeth, the belt being too hard and breaking when wound around a pulley, or cracks occurring on the back of the belt during driving. The core wire of the toothed belt described above contains carbon filaments. Since the carbon filaments have a high elastic modulus, even when a high load is applied to the toothed belt, deformation is less likely to occur, and meshing with the pulley is less likely to shift. Therefore, it is possible to avoid the belt meshing with the pulley being misaligned and the belt riding up on the pulley, or a local force being applied to the belt and the belt teeth chipping. In addition, since carbon filaments do not have creep characteristics like filaments made of organic fibers, the toothed belt is very difficult to stretch, and a decrease in tension is less likely to occur in this toothed belt. In the toothed belt described above, furthermore, the core wire is not exposed on the belt end face. Therefore, dust generation caused by the exposure of the core wire is prevented. The toothed belt described above has low dust generation properties and is suitable for high-load transmission.

[0013] (2) In the toothed belt described above, it is preferable that the elastomer component is a polyamide-based thermoplastic elastomer (TPAE). TPAE is suitable as a material for forming the tooth rubber part and the back rubber part of the toothed belt in that it has a small energy loss with respect to dynamic deformation, little heat generation due to bending, and excellent chemical resistance.

[0014] (3) In the toothed belt described above, it is preferable that the side member is made of a polyamide resin composition or a thermoplastic elastomer composition. In this case, the side member can be adhered to the end face of the belt body by heat fusion. This toothed belt can easily cover the end face of the belt body with the side member.

[0015] (4) In the toothed belt described above, it is preferable that the tooth covering material is made of a polyamide film. In this case, dust generation caused by the tooth covering material is prevented.

[0016] (5) In the toothed belt described above, the polyamide film includes a matrix made of polyamide and granular wear modifiers dispersed in the matrix, and it is preferable that the granular wear modifiers are exposed on the inner peripheral surface of the belt. In this case, the granular wear modifiers contribute to reducing the friction coefficient of the inner peripheral surface of the belt. Since the frictional energy received by the inner peripheral surface of the belt is reduced, the toothed belt can suppress the progress of wear. Since the temperature rise due to friction is suppressed, a decrease in the rigidity of the tooth rubber part is prevented. The tooth rubber part is difficult to deform.

[0017] (6) In the toothed belt described above, it is preferable that the granular wear modifiers are at least one of ultra-high molecular weight polyethylene (UHMWPE) particles and PTFE (polytetrafluoroethylene) particles. In this case, the granular wear modifiers effectively contribute to reducing the friction coefficient of the inner peripheral surface of the belt.

[0018] (7) In the toothed belt described above, it is preferable that the soft segment of the elastomer component has a polyether structure. In this case, TPAE is likely to exhibit rubber elasticity at normal temperature. Therefore, it is suppressed that it is damaged when wound around a pulley or cracks occur on the back surface of the belt during driving. Since it exhibits rubber elasticity at normal temperature, the blending of a plasticizer is unnecessary. TPAE having this soft segment contributes to the low dust generation property of the toothed belt.

[0019] (8) In the toothed belt described above, it is preferable that the back rubber part or the tooth rubber part is made of a thermoplastic elastomer composition that does not contain a plasticizer. In this case, this thermoplastic elastomer composition contributes to the low dust generation property of the toothed belt.

Advantages of the Invention

[0020] According to the present invention, a toothed belt with low dust generation property and suitable for high-load transmission can be obtained.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to these embodiments. FIG. 1 is a perspective view showing a part of a toothed belt 10 according to an embodiment of the present invention. FIG. 2 is a front view of the arrow X in FIG. 1. FIG. 3 is a cross-sectional view taken along the line A-A of FIG. 1.

[0023] <Toothed Belt> The toothed belt 10 is an endless meshing transmission belt. FIG. 1 shows only a part of the toothed belt 10. As shown in FIG. 1, the toothed belt 10 includes a belt body 11, a core wire 13, a tooth covering material 14, and a pair of side members 22.

[0024] The dimensions of the toothed belt 10 are not particularly limited and can be selected according to the design. The dimensions of the toothed belt 10 can be, for example, a belt circumference (belt length at the belt pitch line BL) of 54 mm or more and 6600 mm or less, a belt width of 3 mm or more and 340 mm or less, and a maximum belt thickness of 1.3 mm or more and 13.2 mm or less.

[0025] On the inner circumferential side of the toothed belt 10, a plurality of belt teeth 12 are arranged at a predetermined pitch. The tooth profile of the belt teeth 12 is an S tooth profile. In an embodiment of the present invention, the tooth profile of the belt teeth 12 is not necessarily limited to the S tooth profile, and may be an arc tooth profile other than the S tooth profile, a trapezoidal tooth profile, or other tooth profiles.

[0026] In the toothed belt 10, the belt teeth 12 are straight teeth extending parallel to the belt width direction. In an embodiment of the present invention, the belt teeth 12 may be skew teeth extending in a direction inclined with respect to the belt width direction.

[0027] In the toothed belt 10, the tooth pitch P of the belt teeth 12 (refer to P in FIG. 3) is, for example, 2 mm or more and 20 mm or less. The tooth height of the belt teeth 12 is defined as the dimension from the tooth bottom 15 between a pair of adjacent belt teeth 12 in the belt length direction to the tip of the belt teeth 12 (refer to H in FIG. 3), and is, for example, 0.76 mm or more and 8.4 mm or less. Also, the toothed belt 10 has, for example, 27 or more and 560 or less teeth, a tooth width (dimension in the belt length direction) of, for example, 1.3 mm or more and 15.0 mm or less, and a PLD of, for example, 0.254 mm or more and 2.159 mm or less. These dimensions of the belt teeth are examples and are not necessarily limited to these ranges.

[0028] <Belt body> The belt body 11 has an endless flat belt-shaped back rubber portion 11a and a plurality of toothed rubber portions 11b. The plurality of toothed rubber portions 11b are provided on the inner peripheral side of the belt body 11. Specifically, the plurality of toothed rubber portions 11b are integrally provided at intervals in the belt length direction on the inner peripheral side, which is one side of the back rubber portion 11a. In the belt body 11, each of the back rubber portion 11a and the toothed rubber portions 11b is composed of a thermoplastic elastomer composition. The thermoplastic elastomer composition constituting the back rubber portion 11a and the thermoplastic elastomer composition constituting the toothed rubber portions 11b may be the same or different.

[0029] In the present invention, the thermoplastic elastomer composition refers to a composition that has a thermoplastic elastomer component as an essential component and various additives other than the above elastomer component as optional components that can be contained as required. The above thermoplastic elastomer composition may contain only the elastomer component.

[0030] The elastomer component of the thermoplastic elastomer composition constituting the belt body 11 is a polyamide-based thermoplastic elastomer (TPAE) or a polyester-based thermoplastic elastomer (TPC). Compared with other thermoplastic elastomers such as olefin-based, styrene-based, and urethane-based, TPAE and TPC are more heat-resistant, and the decrease in elastic modulus is small even at the belt temperature during high-load driving or high-speed rotation driving. Therefore, deformation of the toothed rubber portion 11b due to heat generation of the belt is less likely to occur during high-load driving or high-speed rotation driving.

[0031] As the above elastomer component, a polyamide-based thermoplastic elastomer (TPAE) is preferred. Compared with TPC, TPAE has less energy loss for dynamic deformation and less heat generation due to bending. Therefore, the belt temperature during driving is relatively low, making it suitable for power transmission at high loads and high speeds. In addition, TPAE also has excellent chemical resistance. Therefore, it is suitable as an elastomer component of a toothed belt used in applications where contact with chemicals is assumed, such as industrial machines equipped with hydraulic devices, drive units of motorcycles, and electric seats of passenger cars.

[0032] The above polyester-based thermoplastic elastomer (TPC) is a block copolymer that adopts a polyester structure such as polybutylene terephthalate (PBT) as a hard segment and adopts polyether, polyester, or polycarbonate as a soft segment.

[0033] The above polyamide-based thermoplastic elastomer (TPAE) is a block copolymer having polyamide (nylon) as a hard segment and polyol as a soft segment. Examples of the above polyamide (nylon) include nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 1212, etc. Among these, nylon 11 and nylon 12 are preferred because they have a low amide bond content and are less likely to cause dimensional changes.

[0034] As the above polyol, one or both of polyester polyol and polyether polyol can be adopted. When comparing polyester polyol and polyether polyol, polyether polyol is preferred because it is likely to exhibit rubber elasticity at room temperature without blending a plasticizer and is less likely to generate cracks when the belt is bent. In this case, the soft segment has a polyether structure. In addition, when polyether polyol is adopted as the polyol component of TPAE, a plasticizer does not need to be blended. The toothed belt 10 having the tooth rubber portion 11b and the back rubber portion 11a composed of a thermoplastic elastomer composition not containing a plasticizer does not have the plasticizer volatilize and adhere to equipment and products. This thermoplastic elastomer composition contributes to the low dust generation property of the toothed belt 10. Therefore, such a toothed belt 10 can be suitably used in a clean room.

[0035] Examples of the polyester polyol include polyethylene adipate and polybutylene adipate. Examples of the polyether polyol include polytetramethylene ether glycol and polyoxypropylene glycol.

[0036] Commercially available products can also be used as the polyester-based thermoplastic elastomer and the polyamide-based thermoplastic elastomer, respectively. Examples of commercially available products of the polyester-based thermoplastic elastomer include the Hytrel (registered trademark) series manufactured by Toray DuPont Co., Ltd. Examples of commercially available products of the polyamide-based thermoplastic elastomer include the PEBAX (registered trademark) series manufactured by Arkema, the Vestamid (registered trademark) series and the Diamid (registered trademark) series manufactured by Daicel Evonik, and the Grillamid (registered trademark) series manufactured by EMS.

[0037] In the thermoplastic elastomer composition constituting the back rubber portion 11a and the tooth rubber portion 11b, in addition to the elastomer components of TPAE and TPC, if necessary, additives such as short fibers, whiskers, fillers, colorants, antistatic agents, flame retardants, antioxidants, ultraviolet absorbers, light stabilizers, hydrolysis inhibitors, plasticizers, lubricants, antiseptics, fungicides, solid lubricants, lubricating oils, and greases may be included.

[0038] On the other hand, when these additives are contained, these additives may detach from the back rubber portion 11a or the tooth rubber portion 11b and contaminate the use environment. Therefore, in the case where the toothed belt 10 is a toothed belt used in, for example, a clean room, it is preferable that the thermoplastic elastomer composition does not contain the above additives and is composed only of the elastomer component.

[0039] In the belt body 11, the hardness of the thermoplastic elastomer composition constituting the back rubber portion 11a is 25 to 70. The hardness of the thermoplastic elastomer composition constituting the tooth rubber portion 11b is 40 to 70. The hardness of the thermoplastic elastomer composition constituting the tooth rubber portion 11b is equal to or greater than the hardness of the thermoplastic elastomer composition constituting the back rubber portion 11a.

[0040] The hardness of the above thermoplastic elastomer composition is measured at 23°C using a type D durometer in accordance with the provisions of JIS K6253-3. This hardness is also referred to as shore D hardness.

[0041] Hereinafter, in this specification, the hardness of the thermoplastic elastomer composition constituting the back rubber portion 11a is also simply referred to as "back rubber portion hardness", and the hardness of the thermoplastic elastomer composition constituting the tooth rubber portion 11b is also simply referred to as "tooth rubber portion hardness".

[0042] In the toothed belt having such a configuration, since the back rubber portion hardness is within the above range and is equal to or less than the tooth rubber portion hardness, it is possible to suppress breakage when wound around a pulley or the occurrence of cracks on the back surface of the belt during driving. Further, since the tooth rubber portion hardness is equal to or greater than the back rubber portion hardness and is within the above range, the teeth of the belt are less likely to wear during use and deformation of the belt teeth is less likely to occur. The hardness of the thermoplastic elastomer composition constituting the back rubber portion 11a may be smaller than the hardness of the thermoplastic elastomer composition constituting the tooth rubber portion 11b.

[0043] The difference between the above back rubber portion hardness and tooth rubber portion hardness is preferably 5 or more, and more preferably 10 or more. It is more suitable for suppressing the occurrence of back surface cracks.

[0044] In the toothed belt 10, it is also preferable that the back rubber portion hardness is 25 to 50 and the tooth rubber portion hardness is 45 to 65. In this case, it is suitable for achieving both suppression of the occurrence of back surface cracks and suppression of deformation of the belt teeth.

[0045] The hardness of the back rubber part can be controlled by adjusting the molecular weight of the elastomer component contained in the thermoplastic elastomer composition constituting the back rubber part 11a, the ratio of the hard segment to the soft segment, the types and amounts of additives other than the elastomer component contained in the thermoplastic elastomer composition, and the like. Similarly, the hardness of the tooth rubber part can be controlled by the elastomer component and additives other than the elastomer component contained in the thermoplastic elastomer composition constituting the tooth rubber part 11b.

[0046] <Core wire> The core wire 13 is arranged and embedded in a part on the inner peripheral side of the back rubber part 11a of the belt body 11 so as to form a helix having a pitch in the belt width direction. The outer diameter of the core wire 13 is, for example, 0.45 mm or more and 3.0 mm or less. The pitch of the core wire 13 (arrangement pitch in the belt width direction) is, for example, 0.5 mm or more and 4.0 mm or less.

[0047] The core wire 13 includes a large number of filaments, and the filaments are twisted. The twisting method of the core wire 13 is not particularly limited, and it may be single twist composed of one twisting layer, or various twists or lang lay twists having two twisting layers, or those having three twisting layers.

[0048] All or part of the filaments contained in the core wire 13 are carbon filaments made of carbon fiber. The filament diameter of the carbon filament is, for example, 5 μm or more and 7 μm or less. The number of carbon filaments contained in the core wire 13 is, for example, 3000 or more. The upper limit of the number of the filaments is not particularly limited, and is, for example, 96000.

[0049] Examples of the carbon filament include PAN-based carbon filaments and pitch-based carbon filaments. From the viewpoint of flexibility, PAN-based carbon filaments are preferable as the carbon filament.

[0050] In the toothed belt 10, the core wire 13 can contain filaments made of fibers other than carbon filaments. Examples of other fibers include inorganic fibers such as glass fibers and metal fibers, and organic fibers such as aramid fibers, polyester fibers, PBO fibers, nylon fibers, and polyketone fibers. When the core wire 13 contains, as constituent materials, carbon filaments and filaments made of other fibers, the proportion of carbon filaments in all the filaments is 50% by mass or more. The higher the proportion of the carbon filaments (for example, 90% by mass or more), the more preferable.

[0051] As described above, the core wire 13 contains carbon filaments. Since the elastic modulus of the carbon filaments is high, the toothed belt 10 having the core wire 13 is less likely to be deformed even when a high load is applied, and is less likely to be misaligned in meshing with a pulley. Therefore, it is possible to avoid the situation where the toothed belt 10 is misaligned with the pulley and rides on the pulley, or a local force is applied to the toothed belt 10 and the belt teeth 12 are chipped. In addition, since carbon filaments do not have creep characteristics like filaments made of organic fibers, the toothed belt 10 is very difficult to stretch, and it is less likely for the toothed belt 10 to experience a decrease in tension.

[0052] In the toothed belt 10, the core wire 13 may be coated with a convergence coating layer made of a convergence agent for each filament contained in the core wire 13, or may be coated with an adhesion coating layer made of an adhesive for a twisted product of a plurality of filaments. Examples of the convergence agent and the adhesive include an emulsion in which an epoxy group-containing compound and a curing agent are dispersed in water, an aqueous solution containing an initial condensate of resorcin and formaldehyde (also referred to as RF solution), and an aqueous solution containing an initial condensate of resorcin and formaldehyde and latex (also referred to as RFL solution).

[0053] In the toothed belt 10, the core wire 13 may be provided in a double helix using two types of S-twisted yarn and Z-twisted yarn, arranged alternately in the belt width direction. In this case, it is suitable for suppressing the deviation during the running of the toothed belt 10. The core wire 13 may be composed of only S-twisted yarn or only Z-twisted yarn.

[0054] <Tooth covering material> The tooth covering material 14 is affixed so as to cover the inner peripheral surface where a plurality of tooth rubber portions 11b of the belt body 11 are provided. Therefore, the tooth rubber portions 11b of each belt tooth 12 are covered with the tooth covering material 14. This prevents the thermoplastic elastomer composition constituting the tooth rubber portion 11b from coming into direct contact with the pulley. Therefore, wear of the tooth rubber portion 11b can be suppressed. The thickness of the tooth covering material 14 is, for example, 0.1 mm or more and 2.5 mm or less.

[0055] From the viewpoint of contributing to the low dust generation property of the toothed belt 10, the tooth covering material 14 is preferably made of a resin film. Examples of the material of the resin film include polyamide (nylon), polyester, etc. In this case, since the tooth covering material 14 can be adhered to the belt body 11 by heat fusion, the adhesion treatment performed on the tooth covering material made of a fiber member is not required to enhance the adhesive force with the belt body 11. Among resin films, a polyamide film (nylon film) having a polyamide as a resin component is more preferable. Since the polyamide film has a low coefficient of friction, the frictional energy is small and it is difficult to wear. Since the polyamide film has a high melting point, even if the temperature of the contact portion with the pulley rises, it is difficult to cause rapid wear due to the melting of the polyamide. Therefore, the tooth covering material 14 made of a polyamide film can effectively contribute to the low dust generation property of the toothed belt 10.

[0056] Examples of the polyamide (nylon) constituting the polyamide film include nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 1212, nylon 6T, and the like. As the polyamide, commercially available products may be used. Examples of the commercially available products include the Leona (registered trademark) series manufactured by Asahi Kasei Corporation.

[0057] The polyamide film may be composed of only polyamide or may contain other components. In particular, the polyamide film preferably contains a granular wear modifier as another component. The polyamide film includes a matrix made of polyamide and granular wear modifiers dispersed in the matrix, and it is more preferable that the granular wear modifiers are exposed on the inner peripheral surface of the belt. In this case, the granular wear modifiers contribute to reducing the friction coefficient of the inner peripheral surface of the belt. Since the frictional energy received by the inner peripheral surface of the belt is reduced, the progress of wear is suppressed. Since the temperature rise due to friction is suppressed, a decrease in the rigidity of the tooth rubber portion 11b is prevented. This tooth rubber portion 11b is difficult to deform.

[0058] Examples of the material of the granular wear modifier include fluororesins such as polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), ethylene tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF), and ultra-high molecular weight polyethylene (UHMWPE) having a weight average molecular weight of 1,000,000 or more. The granular wear modifiers made of these materials may be used alone or in combination of two or more.

[0059] More preferably, the polyamide film contains at least one of ultra-high molecular weight polyethylene (UHMWPE) particles and polytetrafluoroethylene (PTFE) particles as the granular wear modifier. These particles function as a wear modifier and make the friction coefficient of the tooth portion coating material 14 lower. By containing these particles and reducing the friction coefficient of the tooth covering material 14 (i.e., the friction coefficient of the surface of the belt teeth), the above-described effects can be enjoyed.

[0060] The weight average molecular weight of the UHMWPE constituting the above-mentioned ultra-high molecular weight polyethylene particles is preferably 1.1 million to 3.3 million. When the weight average molecular weight of the above UHMWPE is less than 1.1 million, the UHMWPE particles may melt and disappear due to the frictional heat between the tooth rubber part 11b and the pulley during use. On the other hand, when the weight average molecular weight of the above UHMWPE exceeds 3.3 million, there are UHMWPE particles that may crack due to impact during use, and a sufficient friction coefficient reduction effect may not be obtained.

[0061] The average particle diameter of the above UHMWPE particles is preferably 10 to 65 μm. When the above average particle diameter is less than 10 μm, the exposure amount of the above UHMWPE particles on the surface of the belt teeth 12 is small, and the effect of incorporating them into the polyamide film may be poor. On the other hand, when the above average particle diameter exceeds 65 μm, it may fall off from the surface of the belt during use. The average particle diameter of the above UHMWPE particles is a value measured by a laser diffraction type particle size distribution measuring device. As the above UHMWPE particles, commercially available products may be used.

[0062] The average particle diameter of the above PTFE particles is preferably 10 to 30 μm. When the above average particle diameter is less than 10 μm, the exposure amount of the above PTFE particles on the surface of the belt teeth 12 is small, and the effect of incorporating them into the polyamide film may be poor. On the other hand, when the above average particle diameter exceeds 30 μm, it may fall off from the surface of the belt during use. The average particle diameter of the above PTFE particles is a value measured by a laser diffraction type particle size distribution measuring device. As the above PTFE particles, commercially available products may be used. Examples of the above commercially available products include Fluon (registered trademark) PTFE L150J, Fluon PTFE L169J manufactured by AGC, and Algoflon (registered trademark) L100 manufactured by Solvey.

[0063] The granular wear modifier is preferably exposed on the surface of the tooth covering material 14 that constitutes the inner peripheral surface of the belt by a total of 1 to 15%. When the exposed amount on the surface of the tooth covering material 14 is less than 1%, the effect of lowering the friction coefficient of the surface of the belt tooth 12 is poor. On the other hand, when the exposed amount exceeds 15%, the adhesion between the tooth covering material 14 and the thermoplastic elastomer composition that constitutes the tooth rubber part 11b may be inhibited by the granular wear modifier intervening between the two.

[0064] The exposed amount (%) of the granular wear modifier on the surface of the tooth covering material 14 is obtained by observing the surface of the tooth covering material 14 with an optical microscope and calculating the ratio of the area of the granular wear modifier to the area of the surface of the tooth covering material 14.

[0065] The adjustment of the exposed amount of the granular wear modifier on the belt surface (that is, the surface of the tooth covering material 14) can be carried out by changing the concentration and dispersion state of the granular wear modifier contained in the polyamide film that forms the tooth covering material 14, etc. It can also be adjusted by polishing the surface of the polyamide film containing the granular wear modifier.

[0066] The polyamide film as the tooth covering material 14 may contain other additives in addition to the above-mentioned granular wear modifier. Examples of other additives include fillers, colorants, antistatic agents, flame retardants, antioxidants, ultraviolet absorbers, light stabilizers, hydrolysis inhibitors, plasticizers, lubricants, preservatives, fungicides, etc.

[0067] <Side member> Each side member 22 is laminated on the end face 11s of the belt body 11. This side member 22 forms the belt end face 10s of the toothed belt 10. The side member 22 is composed of a sheet having a predetermined thickness. This side member 22 may be composed of a thin film. The thickness of this side member 22 is, for example, 0.1 mm or more and 2.5 mm or less.

[0068] The side member 22 covers the core wire 13 exposed on the end face 11s of the belt body 11. Therefore, as shown in FIG. 1, the core wire 13 is not exposed on the belt end face 10s. In this toothed belt 10, dust generation caused by the exposure of the core wire 13 is prevented. In FIG. 1, the entire end face 11s of the belt body 11 is covered by the side member 22, but at least the core wire 13 exposed on the end face 11s of the belt body 11 only needs to be covered by this side member 22.

[0069] The side member 22 preferably consists of a polyamide resin composition or a thermoplastic elastomer composition. The polyamide resin composition and the thermoplastic elastomer composition have thermoplasticity. Therefore, since the side member 22 consists of a polyamide resin composition or a thermoplastic elastomer composition, the side member 22 can be adhered to the end face 11s of the belt body 11 by heat fusion. This toothed belt 10 can easily cover the end face 11s of the belt body 11 with the side member 22. When the side member 22 consists of a thermoplastic elastomer composition, the thermoplastic elastomer composition exemplified in the description of the belt body 11 can be used as the thermoplastic elastomer composition of the side member 22. In this case, the thermoplastic elastomer composition of the side member 22 may be the same as or different from the thermoplastic elastomer composition constituting the back rubber part 11a or the tooth rubber part 11b described above. From the viewpoint that the side member 22 can be firmly adhered to the end face 11s of the belt body 11, it is preferable that the thermoplastic elastomer composition of the side member 22 is the same as the thermoplastic elastomer composition constituting the back rubber part 11a or the tooth rubber part 11b described above. In this case, from the viewpoint of low dust generation, it is more preferable that the side member 22 consists of a thermoplastic elastomer composition that does not contain a plasticizer.

[0070] The polyamide resin composition uses polyamide as the resin component. Since the polyamide resin composition has a low coefficient of friction, the frictional energy is small and it is difficult to wear. The side member 22 may come into contact with the flange of the pulley. Therefore, by forming the side member 22 from the polyamide resin composition, this side member 22 can effectively contribute to the low dust generation property of the toothed belt 10. From this viewpoint, it is preferable that the side member 22 is made of the polyamide resin composition.

[0071] Examples of the polyamide include nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 1212, and the like. Among these, nylon 6 and nylon 66 are preferable from the viewpoints of wear resistance and low cost. As the above polyamide, commercially available products may be used. Examples of the above commercially available products include the Leona (registered trademark) series manufactured by Asahi Kasei Corporation.

[0072] When the side member 22 is made of the polyamide resin composition, the polyamide resin composition may be composed of only polyamide, or may contain other additives in addition to polyamide. Examples of other additives include fillers, colorants, antistatic agents, flame retardants, antioxidants, ultraviolet absorbers, light stabilizers, hydrolysis inhibitors, plasticizers, lubricants, preservatives, fungicides, and the like.

[0073] Next, the manufacturing method of the toothed belt 10 according to the present embodiment will be described.

[0074] (Manufacturing method) This manufacturing method will be described with reference to FIGS. 4 to 8. FIG. 4 is a partial cross-sectional view of a belt molding die used in the manufacturing method of the toothed belt 10. FIGS. 5 to 8 are diagrams for explaining the manufacturing process of the manufacturing method. The manufacturing method includes a material preparation step, a lamination step, a molding step, and a finishing step.

[0075] <Material preparation step> ≪Elastomer sheet≫ Prepare a thermoplastic elastomer sheet for the back rubber part and a thermoplastic elastomer sheet for the tooth rubber part. Each elastomer sheet can be obtained, for example, by preparing a thermoplastic elastomer composition containing a TPAE or TPC as an elastomer component and necessary additives, and molding this composition into a sheet shape by extrusion molding or the like. Also, the thermoplastic elastomer sheet for the back rubber part and the thermoplastic elastomer sheet for the tooth rubber part may be molded by coextrusion. In this case, a laminate of the thermoplastic elastomer sheet for the back rubber part and the thermoplastic elastomer sheet for the tooth rubber part is obtained. The elastomer sheet molded in this step may be wound up once, or may be directly supplied to the next step.

[0076] ≪Tooth Coating Material≫ Taking the case where the tooth coating material 14 is made of a polyamide film as an example, the preparation of this tooth coating material 14 will be described. The polyamide film has a concave portion with the same shape as the tooth shape of the toothed belt 10, is placed along a heated mold, and a soft elastic body is pressed from the side opposite to the mold to mold the polyamide film into a toothed shape. Alternatively, after extruding the polyamide film by extrusion molding, it is passed through two rolls having tooth shapes with the same shape as the tooth shape of the belt, and while cooling, a toothed shape is formed on the polyamide film to produce a toothed polyamide film. Alternatively, a toothed polyamide film is produced by passing the polyamide film through two rolls having heated tooth shapes. Thereafter, the toothed polyamide film may be formed into a cylindrical shape.

[0077] ≪Core Wire≫ Apply a predetermined twist, adhesion treatment, etc. to the filament 18 to prepare the core wire 13. Here, it is preferable to prepare an S-twisted core wire and a Z-twisted core wire as a pair of core wires.

[0078] ≪Side Member≫ Prepare a sheet made of a thermoplastic elastomer composition or a polyamide resin composition for forming the side member 22. Punch out this sheet into the shape of the belt end face of the toothed belt 10 to produce a side member sheet.

[0079] <Laminating process> FIG. 4 is a partial cross-sectional view showing a part of the belt forming die 30. The belt forming die 30 is cylindrical and has an outer peripheral surface on which a plurality of tooth portion forming grooves 31 formed so as to extend in the axial direction are arranged at intervals in the circumferential direction.

[0080] As shown in FIG. 5, cover the outer peripheral surface of the belt forming die 30 with a cylindrical tooth portion reinforcing agent 14 having a tooth shape, and wind a pair of core wires 13 spirally thereon. Then, wind a thermoplastic elastomer sheet 11b' for the tooth rubber portion and a thermoplastic elastomer sheet 11a' for the back rubber thereon in this order. The number of layers of each wound sheet may be one layer or two or more layers according to the dimensions of the belt to be produced. Furthermore, a release paper or a release film (not shown) is wound as necessary. Thereby, a laminate S' is formed on the belt forming die 30.

[0081] <Forming process> Cover the laminate S' with a jacket having a rubber sleeve 32 on its inner surface and having a sealed space between the sleeve 32 and the main body. Thereby, as shown in FIG. 6, the rubber sleeve 32 is covered on the laminate S' on the belt forming die 30. Inject high-pressure steam into the inside of the forming die 30 around which the laminate S' is wound and the space of the jacket, and heat and compress. Thereby, the thermoplastic elastomer constituting the thermoplastic elastomer sheets 11a' and 11b' passes through the gaps between the core wires 13 and flows into the tooth portion forming grooves 31 to form the belt teeth 12 as shown in FIG. 7. At this time, the temperature of the high-pressure steam shall be a temperature equal to or higher than the temperature at which the thermoplastic elastomer flows. When the elastomer component of the thermoplastic elastomer sheet is TPAE, the temperature of the high-pressure steam shall be 170°C or higher.

[0082] After forming the belt teeth 12, cool the jacket and the mold 30 with water or the like to lower the temperature of the elastomer to 100°C or lower, and then take out the mold 30 and the molded body S from the jacket. Further, when the temperature of the molded body S is 40°C or higher, further cool it. When the temperature of the molded body S drops below 40°C, remove the molded body S from the mold 30.

[0083] <Finishing process> By cutting and separating the taken-out molded body S into a specified width, the belt body 11 shown in Fig. 8(a) is obtained. After attaching the side member sheet 22' to the end face 11s of the belt body 11, press a hot plate against the side member sheet 22'. Heat the side member sheet 22' and weld this side member sheet 22' to the end face 11s of the belt body 11. Thereby, the toothed belt 10 shown in Fig. 8(b) is obtained. By going through the steps described above, a toothed belt 10 can be manufactured in which the belt body 11 is composed of a thermoplastic elastomer composition and the core wire 13 is not exposed on the belt end face 10s.

[0084] <Others> When the hardness of the thermoplastic elastomer sheet 11b' for the tooth rubber part is different from that of the thermoplastic elastomer sheet 11a' for the back rubber part, on the outer peripheral surface of the belt mold 30, laminate the tooth covering material 14, the core wire 13, and the thermoplastic elastomer sheet 11b' for the tooth rubber part, then perform the heating and compression with the above-mentioned high-pressure steam to form the belt teeth 12. After cooling once, wind the thermoplastic elastomer sheet 11a' for the back rubber part around it, perform the heating and compression with the high-pressure steam again, then cool it again, and finally perform the finishing process to manufacture the toothed belt 10.

Example

[0085] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the following examples.

[0086] Here, a toothed belt with an S8M tooth profile was manufactured and its performance was evaluated. The toothed belts of each example were manufactured using the manufacturing method described above. Materials for the belt body, the core wire, the material for the tooth coating, and the material for the side members were prepared as follows.

[0087] (Materials for the belt body) The following thermoplastic elastomer compositions (TPE) were prepared. All of the thermoplastic elastomer compositions are commercially available products.

[0088] (TPAE: Polyamide-based thermoplastic elastomer composition) (A1) PEBAX (registered trademark) 4033SP-01 manufactured by Arkema was used. The hardness of this thermoplastic elastomer composition is 42. PEBAX uses polyether polyol as the soft segment. (A2) TPAE-10 manufactured by T&K TOKA was used. The hardness of this thermoplastic elastomer composition is 41. TPAE-10 uses polyether ester as the soft segment. (A3) PEBAX (registered trademark) 2533SP-01 manufactured by Arkema was used. The hardness of this thermoplastic elastomer composition is 27.

[0089] (TPO: Polyolefin-based thermoplastic elastomer composition) Thermolane (registered trademark) QT85KB manufactured by Mitsubishi Chemical was used. The hardness of this thermoplastic elastomer composition is 31.

[0090] (TPS: Styrene-based thermoplastic elastomer composition) Ravaron (registered trademark) QE548AE manufactured by Mitsubishi Chemical was used. The hardness of this thermoplastic elastomer composition is 42.

[0091] <TPU: Polyurethane-based thermoplastic elastomer composition> Milacron (registered trademark) E490 manufactured by Nippon Milacron Co., Ltd. was used. The hardness of this thermoplastic elastomer composition is 43.

[0092] (Material for side member) The following polyamide-based thermoplastic elastomer composition (TPAE) and polyamide resin composition (PA) were prepared. Both are commercially available products and were prepared as sheets with a thickness of 0.5 mm. <TPAE: Polyamide-based thermoplastic elastomer composition> PEBAX (registered trademark) 4033SP-01 manufactured by Arkema was used. The hardness of this thermoplastic elastomer composition is 42. PEBAX uses polyether as the soft segment. <PA: Polyamide resin composition> Rena 1500 manufactured by Asahi Kasei Corporation was used.

[0093] (Core wire) Carbon core wire (manufactured by Teijin Tenax Co., Ltd., filament diameter 7 μm, number of filaments 15000) was used to prepare S-twisted yarn and Z-twisted yarn. This core wire is a 1×5 multi-twisted yarn and has been treated with an epoxy-based adhesive.

[0094] (Tooth coating material) As the tooth coating material, the following polyamide films PA1 to PA3 were prepared. <Polyamide film PA1> A film with a thickness of 0.65 mm made of "Rena 1500" manufactured by Asahi Kasei Corporation was prepared. <Polyamide film PA2> A polyamide resin composition prepared by blending a predetermined amount of UHMWPE particles (Mipiron XM-220 manufactured by Mitsui Chemicals, Inc.) with Leonar 1500 was formed into a sheet by extrusion molding to produce a film with a thickness of 0.65 mm. The concentration of UHMWPE particles in the polyamide resin composition was 15% by mass. In the production of the tooth coating material PA2, after extrusion molding, the surface of the obtained sheet was polished to adjust the exposure amount of UHMWPE particles. <Polyamide film PA3> A polyamide resin composition prepared by blending a predetermined amount of PTFE particles (Fluon PTFE L150J manufactured by AGC Inc.) with Leonar 1500 was formed into a sheet by extrusion molding to produce a film with a thickness of 0.65 mm. The concentration of PTFE particles in the polyamide resin composition was 20% by mass. In the production of the tooth coating material PA3, after extrusion molding, the surface of the obtained sheet was polished to adjust the exposure amount of PTFE particles.

[0095] [Example 1] Using the above TPAE (A1) for the belt body having a back rubber part and a tooth rubber part, using the above TPAE for the side members, using the above polyamide film PA1 for the tooth coating material, and using the above core wire, a toothed belt with a tooth type of S8M was manufactured by the above-described manufacturing method (see FIGS. 5 to 9). Example 1 does not contain a plasticizer. For the durability test, a toothed belt with a belt width of 8 mm and a belt length of 1200 mm was prepared, and for the dust generation amount evaluation, a toothed belt with a belt width of 30 mm and a belt length of 1200 mm was prepared.

[0096] [Example 2] A toothed belt of Example 2 was obtained in the same manner as in Example 1 except that the side members were as shown in Table 1 below. Example 2 does not contain a plasticizer.

[0097] [Comparative Example 1] A toothed belt of Comparative Example 1 was obtained in the same manner as in Example 1 except that the core wire was exposed at the belt end face. In Comparative Example 1, no side members are provided. Comparative Example 1 does not contain a plasticizer.

[0098] [Examples 3 to 4] A toothed belt for Examples 3 to 4 was obtained in the same manner as in Example 1, except that the tooth covering material was as shown in Table 1 below. Examples 3 to 4 do not contain a plasticizer. In Example 3, the exposed amount of UHMWPE particles was 10.3%. In Example 4, the exposed amount of PTFE particles was 12.4%.

[0099] [Example 5] A toothed belt for Example 5 was obtained in the same manner as in Example 1, except that the side member and the belt body were as shown in Table 1 below. Example 5 does not contain a plasticizer.

[0100] [Comparative Examples 2 to 4] A toothed belt for Comparative Examples 2 to 4 was obtained in the same manner as in Example 1, except that the belt body was as shown in Table 2 below. Comparative Examples 2 to 4 do not contain a plasticizer.

[0101] [Example 6] A toothed belt for Example 6 was obtained in the same manner as in Example 1, except that the back rubber part used the above TPAE (A3) and the tooth rubber part used the above TPAE (A1). Example 6 does not contain a plasticizer.

[0102] (Evaluation Method) For the toothed belts manufactured in the examples and comparative examples, a durability test for evaluating durability and a dust generation amount evaluation test for evaluating dust generation property were conducted. The results are shown in Table 1.

[0103] [Durability Test] The durability test is a test for evaluating durability under standard running conditions. It was conducted on the toothed belts manufactured in Examples 1 to 6 and Comparative Examples 2 to 4. Figure 10 shows the belt running test machine 80 used in the durability test 1. The belt running test machine 80 includes a driving pulley 81 with 22 teeth and a tooth profile of 8M, and a driven pulley 82 with 33 teeth and a tooth profile of 8M provided on the right side thereof. The driven pulley 82 is provided so as to be movable left and right so as to be able to load an axial load (dead weight).

[0104] For each of the toothed belts 110 manufactured in Examples 1 to 6 and Comparative Examples 2 to 4, it was wound around between the driving pulley 81 and the driven pulley 82 of the belt running tester 80, and an axial load of 608 N was applied to the right side of the driven pulley 82 to apply a belt tension, and a rotational load of 34.2 N·m was applied to the driven pulley 82. At room temperature, the driving pulley 81 was rotated at a rotational speed of 4200 revolutions per minute for 1 minute to run the belt. Then, the belt running was periodically stopped, and the presence or absence of failures such as cracks on the back surface of the back rubber was visually confirmed, and the belt running time until the occurrence of a failure was measured. Note that the maximum belt running time was set to 500 hours. Also, when tooth skipping occurred even though no failure occurred, the test was terminated at that point.

[0105] <Dust generation amount evaluation test> The dust generation amount evaluation test is a test for evaluating the amount of dust generated during belt running. It was conducted on the toothed belts manufactured in Examples 1 to 6 and Comparative Example 1. This evaluation follows the method for measuring the dust generation amount from the moving mechanism of equipment used in a clean room of JIS B9926. FIG. 11 shows the belt running tester 90 used in the dust generation amount evaluation test. The belt running tester 90 includes a test specimen installation part 91. In this test specimen installation part 91, a driving pulley 92 with 24 teeth and a tooth profile of 8M and a driven pulley 93 with 24 teeth and a tooth profile of 8M provided on the right side thereof are provided. The driven pulley 93 is provided so as to be movable left and right so that an axial load (dead weight) can be applied. An air blowing part 94 is provided on the upstream side of the test specimen installation part 91. By this air blowing part 94, outside air is taken in. An air filter part 95 is provided on the downstream side of the air blowing part 94. By passing the outside air through this air filter part 95, clean air is introduced into the test specimen installation part 91. The air that has passed through the test specimen installation part 91 is discharged to the outside through the measuring part 96. A dust generation sensor (not shown) is provided in this measuring part 96, and the amount of dust generation is measured by this dust generation sensor.

[0106] For each of the toothed belts 120 manufactured in Examples 1 to 6 and Comparative Example 1, it was wound between the driving pulley 92 and the driven pulley 93 of the belt running tester 90, and an axial load of 687 N was applied to the right side of the driven pulley 93 to apply a belt tension. At room temperature, the driving pulley 92 was rotated at a rotational speed of 200 revolutions per minute for 1 minute to run the belt. And the dust generation property was evaluated by comparing the average value per minute of the integrated dust generation amount when the toothed belt was run for 10 minutes.

[0107]

Table 1

[0108]

Table 2

[0109] As shown in Tables 1-2, the toothed belt according to the embodiment of the present invention has low dust generation property and is suitable for high-load transmission.

Industrial Applicability

[0110] The present invention is useful in the technical field of toothed belts using a plasticizable elastomer composition as a material for the tooth rubber part and the back rubber part.

Explanation of Signs

[0111] 10, 110, 120 Toothed belt Belt end face of the toothed belt 10 of 10s 11 Belt body End face of the belt body 11 of 11s 11a Back rubber part 11b Tooth rubber part 12 Belt teeth 13 Core wire 14 Tooth part covering material 15 Tooth bottom 16 Yarn 17 Strand 18 Filament 22 Side member 30 Belt forming die 31 Tooth forming groove 32 Rubber sleeve 80, 90 Testing machines 81, 92 Driving pulleys 82, 93 Driven pulleys 91 Test specimen installation part 94 Air blowing part 95 Air filter part 96 Measuring part

Claims

1. A belt body having a flat belt-shaped back rubber part and a plurality of tooth rubber parts arranged on the inner peripheral side of the back rubber part and each integrally provided on the back rubber part to form belt teeth, wherein both the back rubber part and the tooth rubber parts are made of a thermoplastic elastomer composition; A core wire arranged and embedded so as to form a helix having a pitch in the belt width direction in a portion on the inner peripheral side of the back rubber part; A tooth part covering material covering the plurality of tooth rubber parts provided on the inner peripheral side of the belt body; A side member laminated on the end face of the belt body to form the belt end face; Comprising; The elastomer component of the thermoplastic elastomer composition is a polyamide-based thermoplastic elastomer (TPAE) or a polyester-based thermoplastic elastomer (TPC); The hardness of the thermoplastic elastomer composition constituting the back rubber part is 25 to 70; The hardness of the thermoplastic elastomer composition constituting the tooth rubber part is 40 to 70 and is not less than the hardness of the thermoplastic elastomer composition constituting the back rubber part; The side member is a sheet or film made of a molded product of a thermoplastic elastomer composition containing no plasticizer; The core wire includes a carbon filament made of carbon fiber and is not exposed on the belt end face, a toothed belt.

2. The toothed belt according to claim 1, wherein the elastomer component is a polyamide-based thermoplastic elastomer (TPAE).

3. The toothed belt according to claim 1 or 2, wherein the tooth part covering material is made of a polyamide film.

4. The polyamide film includes a matrix made of polyamide and granular wear modifiers dispersed in the matrix; The toothed belt according to claim 3, wherein the granular wear modifiers are exposed on the inner peripheral surface of the belt.

5. The toothed belt according to claim 4, wherein the granular wear modifiers are at least one of ultra-high molecular weight polyethylene (UHMWPE) particles and PTFE (polytetrafluoroethylene) particles.

6. The toothed belt according to any one of claims 2 to 5, wherein the soft segment of the elastomer component has a polyether structure.

7. The toothed belt according to any one of claims 1 to 6, wherein the back rubber part or the tooth rubber part is made of a thermoplastic elastomer composition containing no plasticizer.

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