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 part, a large number of tooth rubber parts integrally provided in the back rubber part at a predetermined pitch in the longitudinal direction of the belt, and a core wire embedded between the back rubber part and the tooth rubber part so as to extend in the longitudinal direction of the belt and at a predetermined pitch in the width direction of the belt. The two differ in that the back rubber part and the tooth rubber part are formed of vulcanized rubber or cast urethane.

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

[0004] As a toothed belt that can solve such problems, a toothed belt in which the back rubber part and the tooth rubber part 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] Toothed belts using thermoplastic elastomers for the back rubber and tooth rubber portions had the problem that the belt teeth were prone to deformation when the load on the belt increased. Furthermore, when the rotational speed of the pulley on which the belt was attached increased, the belt generated heat, and in this case as well, the belt teeth were prone to deformation.

[0007] In the aforementioned Patent Document 2, a single-twist yarn, which is made by twisting a filament made of carbon fiber (hereinafter referred to as carbon filament) on one side, is used as the core wire. Carbon fibers are less susceptible to deformation due to creep compared to organic fibers. Therefore, by using a yarn made of carbon fibers as the core wire, the toothed belt can suppress the decrease in tension due to use. This toothed belt is expected to be usable for a long period of time.

[0008] Incidentally, in the manufacture of toothed belts, a tubular belt slab is produced. By cutting this belt slab into sections of a predetermined width, a toothed belt is obtained. The end face of the toothed belt consists of a cut surface, and the core wire is exposed at this end face. Fiber debris is generated and scattered from the exposed core wire, so this toothed belt cannot be used in environments where air cleanliness is controlled, such as a clean room. Carbon fibers are conductive. Therefore, if carbon fiber debris adheres to the circuitry of electrical equipment, for example, it could cause a short circuit and potentially lead to the failure of the electrical equipment. The extrusion method allows for the production of toothed belts without exposing the core wires at the belt ends. However, this method involves forming belts of a predetermined length and connecting the ends of these belts to obtain a toothed belt. Therefore, even if high-strength carbon fibers are used for the core wires, this toothed belt cannot be used as a power transmission belt where high load transmission is required.

[0009] This invention has been made in view of these circumstances, and aims to provide a toothed belt that is low in dust generation and suitable for high-load transmission. [Means for solving the problem]

[0010] (1) The toothed belt of the present invention has a belt body having a flat strip-shaped back rubber portion and a plurality of tooth rubber portions disposed on the inner circumference side of the back rubber portion, each integrally provided with the back rubber portion and constituting belt teeth, wherein both the back rubber portion and the tooth rubber portion are made of a thermoplastic elastomer composition, a core wire is embedded in the inner circumference side of the back rubber portion so as to form a spiral having a pitch in the belt width direction, a tooth portion covering material that covers the plurality of tooth rubber portions provided on the inner circumference side of the belt body, and a side portion laminated on the end face of the belt body and forming the belt end face The material comprises a material wherein 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 portion is 25 to 70, the hardness of the thermoplastic elastomer composition constituting the tooth rubber portion is 40 to 70 and greater than or equal to the hardness of the thermoplastic elastomer composition constituting the back rubber portion, and the core wire contains carbon filaments made of carbon fibers and is not exposed on the belt end face.

[0011] In the toothed belt described above, the back rubber portion and the tooth rubber portion are made of a composition in which polyamide-based thermoplastic elastomer (TPAE) or polyester-based thermoplastic elastomer (TPC) is used as the elastomer component. Therefore, the manufacturing process does not require a vulcanization or post-vulcanization process, and this toothed belt has excellent productivity. In addition, the above elastomer component is heat resistant, and the decrease in elastic modulus is small even at the heat generated when the belt is driven under high load or at high rotational speed. Therefore, deformation is less likely to occur when the belt is driven, and problems such as tooth skipping caused by deformation of the tooth rubber portion are less likely to occur.

[0012] In the toothed belt described above, the thermoplastic elastomer composition constituting the back rubber portion and the tooth rubber portion each has a specific hardness. Therefore, it is possible to prevent the belt from deforming and chipping its teeth when subjected to power because it is too soft, from breaking when wrapped around a pulley because it is too hard, and from cracking on the back of the belt during operation. The core of the toothed belt described above contains carbon filaments. Because carbon filaments have a high modulus of elasticity, the toothed belt is less likely to deform even when subjected to high loads, and the engagement with the pulley is less likely to shift. Therefore, it is possible to avoid the belt riding up on the pulley due to misalignment of the belt and pulley, or the belt teeth breaking due to localized force on the belt. In addition, since carbon filaments do not have creep properties like filaments made of organic fibers, the toothed belt is very resistant to stretching, and tension loss is less likely to occur in this toothed belt. Furthermore, in the toothed belt described above, the core wires are not exposed at the belt end face. Therefore, dust generation caused by exposed core wires is prevented. The toothed belt described above is low-dusting and suitable for high-load power transmission.

[0013] (2) In the toothed belt described above, the elastomer component is preferably a polyamide thermoplastic elastomer (TPAE). TPAE is suitable as a material for the toothed rubber portion and back rubber portion of a toothed belt because it has low energy loss with respect to dynamic deformation, generates little heat due to bending, and has excellent chemical resistance.

[0014] (3) In the toothed belt described above, the side member is preferably made of a polyamide resin composition or a thermoplastic elastomer composition. In this case, the side member can be bonded to the end face of the belt body by heat fusion. With this toothed belt, the end face of the belt body can be easily covered 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 portion is prevented. The tooth rubber portion 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 room 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. In order to exhibit rubber elasticity at room temperature, it is not necessary to blend a plasticizer. 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 portion or the tooth rubber portion 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]It is a perspective view schematically showing a part of a toothed belt according to an embodiment of the present invention. [Figure 2] It is a front view as viewed from the arrow X in FIG. 1. [Figure 3] It is an end view taken along the line A-A of FIG. 1. [Figure 4] It is a partial cross-sectional view of a belt forming die used for manufacturing a toothed belt. [Figure 5] It is a diagram for explaining the manufacturing process of a toothed belt. [Figure 6] It is a diagram for explaining the manufacturing process of a toothed belt. [Figure 7] It is a diagram for explaining the manufacturing process of a toothed belt. [Figure 8] It is a perspective view for explaining the attachment of side members. [Figure 9] It is a diagram showing a pulley layout in a running test. [Figure 10] It is a diagram showing a pulley layout in a dust generation test.

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 as viewed from the arrow X in FIG. 1. FIG. 3 is an end view taken along the line A-A of FIG. 1.

[0023] <Toothed belt> The toothed belt 10 is an endless meshing transmission belt. Only a part of the toothed belt 10 is shown in FIG. 1. 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] Multiple belt teeth 12 are arranged on the inner circumference of the toothed belt 10 at predetermined intervals. The tooth profile of the belt teeth 12 is an S-shaped tooth profile. In embodiments of the present invention, the tooth profile of the belt teeth 12 is not limited to an S-shaped tooth profile, but may be an arc-shaped tooth profile other than an S-shaped tooth profile, a trapezoidal tooth profile, or any other tooth profile.

[0026] In the toothed belt 10, the belt teeth 12 are straight teeth that extend parallel to the belt width direction. In embodiments of the present invention, the belt teeth 12 may be serrated teeth that extend 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 (see P in Figure 3) is, for example, 2 mm or more and 20 mm or less. The tooth height of the belt teeth 12 is defined by the distance from the tooth root 15 between a pair of mutually adjacent belt teeth 12 in the belt length direction to the tip of the belt teeth 12 (see H in Figure 3), and is, for example, between 0.76 mm and 8.4 mm. Furthermore, the toothed belt 10 has, for example, 27 to 560 teeth, a tooth width (dimension in the belt length direction) of, for example, 1.3 mm to 15.0 mm, and a PLD of, for example, 0.254 mm to 2.159 mm. These belt tooth dimensions are illustrative and not limited to these ranges.

[0028] <Belt body> The belt body 11 has an endless, flat, strip-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 circumference side of the belt body 11. More specifically, the plurality of toothed rubber portions 11b are integrally provided on the inner circumference side of the back rubber portion 11a at intervals in the length direction of the belt. In the belt body 11, both the back rubber portion 11a and the toothed rubber portions 11b are made of a thermoplastic elastomer composition. The thermoplastic elastomer composition constituting the back rubber portion 11a and the thermoplastic elastomer composition constituting the tooth rubber portion 11b may be the same or different.

[0029] In the present invention, a thermoplastic elastomer composition refers to a composition in which a thermoplastic elastomer component is an essential component, and various additives other than the elastomer component may be included as optional components as needed. 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 either a polyamide-based thermoplastic elastomer (TPAE) or a polyester-based thermoplastic elastomer (TPC). TPAE and TPC are more heat-resistant than other thermoplastic elastomers such as olefin-based, styrene-based, and urethane-based materials, and exhibit less reduction in elastic modulus even at high belt temperatures during high-load or high-speed rotational driving. Therefore, deformation of the tooth rubber portion 11b due to heat generation in the belt is less likely to occur during high-load or high-speed rotational driving.

[0031] As the elastomer component mentioned above, polyamide-based thermoplastic elastomers (TPAEs) are preferred. Compared to TPC, TPAE belts have lower energy loss due to dynamic deformation and generate less heat due to bending. Therefore, the belt temperature during operation is relatively low, making them suitable for power transmission under high load and at high speeds. Furthermore, TPAE exhibits excellent chemical resistance. Therefore, it is suitable as an elastomer component in applications where contact with chemicals is expected, such as industrial machinery equipped with hydraulic systems, the drive systems of motorcycles, and toothed belts used in electric seats of passenger cars.

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

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

[0034] The above-mentioned polyol can be either polyester polyol or polyether polyol, or both. Comparing polyester polyol and polyether polyol, polyether polyol is preferred because it exhibits rubber elasticity at room temperature without the need for plasticizers and is less prone to cracking when the belt is bent. In this case, the soft segment will have a polyether structure. Furthermore, if polyether polyol is used as the polyol component of TPAE, it is not necessary to add a plasticizer. A toothed belt 10 in which the tooth rubber portion 11b and back rubber portion 11a are composed of a thermoplastic elastomer composition that does not contain a plasticizer will not have plasticizer volatilize and adhere to equipment or products. This thermoplastic elastomer composition contributes to the low dust generation of the toothed belt 10. Therefore, such a toothed belt 10 can be suitably used in a cleanroom.

[0035] Examples of the above-mentioned polyester polyols include polyethylene adipate and polybutylene adipate. Examples of the above-mentioned polyether polyols include polytetramethylene ether glycol and polyoxypropylene glycol.

[0036] The polyester-based thermoplastic elastomer and the polyamide-based thermoplastic elastomer mentioned above can also be commercially available products. Examples of commercially available polyester thermoplastic elastomers include the Hytrel® series manufactured by Toray DuPont. Examples of commercially available polyamide-based thermoplastic elastomers include the PEBAX® series from Arkema, the Vestamid® series and Diamide® series from Daicel-Evonik, and the Grillflex® series from EMS.

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

[0038] On the other hand, if these additives are included, they may detach from the back rubber portion 11a or the tooth rubber portion 11b and contaminate the usage environment. Therefore, if the toothed belt 10 is, for example, a toothed belt used in a cleanroom, it is preferable that the thermoplastic elastomer composition does not contain the above additives and is composed only of elastomer components.

[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 greater than or equal to 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 known as Shore D hardness.

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

[0042] In a toothed belt with this configuration, the hardness of the back rubber portion is within the above range and less than or equal to the hardness of the tooth rubber portion, thus preventing damage when wrapped around a pulley and preventing cracks from forming on the back of the belt during operation. Furthermore, since the hardness of the tooth rubber portion is greater than or equal to the hardness of the back rubber portion and within the above range, the belt teeth are less prone to wear and deformation during use. The hardness of the thermoplastic elastomer composition constituting the back rubber portion 11a may be less than the hardness of the thermoplastic elastomer composition constituting the tooth rubber portion 11b.

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

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

[0045] The hardness of the back rubber portion can be controlled by adjusting the molecular weight of the elastomer component contained in the thermoplastic elastomer composition that constitutes the back rubber portion 11a, the ratio of hard segments to soft segments, and the type and amount of additives other than elastomer components contained in the thermoplastic elastomer composition. Similarly, the hardness of the tooth rubber portion can be controlled by the elastomer component and other additives contained in the thermoplastic elastomer composition that constitutes the tooth rubber portion 11b.

[0046] <Heartline> The core wire 13 is embedded in the inner circumference of the back rubber portion 11a of the belt body 11, arranged to form a spiral with 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 wires 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 contains numerous filaments, which are twisted together. The method of twisting the core wire 13 is not particularly limited; it may be a single twist consisting of one twist layer, a multi-twist or Lang twist having two twist layers, or a twist having three twist layers.

[0048] The core wire 13 is a carbon filament in which all or part of the filament consists of carbon fibers. The filament diameter of the carbon filament described above is, for example, between 5 μm and 7 μm. The number of carbon filaments contained in the core wire 13 is, for example, 3,000 or more. There is no particular upper limit to the number of filaments described above, and it is, for example, 96,000.

[0049] Examples of carbon filaments include PAN-based carbon filaments and pitch-based carbon filaments. Due to their flexibility, PAN-based carbon filaments are preferred.

[0050] In the toothed belt 10, the core wire 13 may include filaments made of other fibers in addition to 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 carbon filaments and filaments made of other fibers as constituent materials, the proportion of carbon filaments to the total filaments is 50% by mass or more. A higher proportion of carbon filaments is preferable (for example, 90% by mass or more).

[0051] As mentioned above, the core wire 13 contains carbon filaments. Because carbon filaments have a high modulus of elasticity, the toothed belt 10 having the core wire 13 is less prone to deformation even under high loads, and the engagement with the pulley is less likely to shift. Therefore, it is possible to avoid the toothed belt 10 riding up onto the pulley due to misalignment of the engagement between the toothed belt 10 and the pulley, or the tooth 12 breaking off due to localized force on the toothed belt 10. In addition, since carbon filaments do not have creep properties like filaments made of organic fibers, the toothed belt 10 is very resistant to stretching, and this toothed belt 10 is less prone to tension loss.

[0052] In the toothed belt 10, the core wire 13 may be covered with a converging coating layer made of a converging agent, or the twisted filaments may be covered with an adhesive coating layer made of an adhesive. Examples of converging agents and adhesives include emulsions obtained by dispersing an epoxy group-containing compound and a curing agent in water, aqueous solutions containing an initial condensate of resorcinol and formaldehyde (also referred to as RF solution), and aqueous solutions containing an initial condensate of resorcinol and formaldehyde and latex (also referred to as RFL solution).

[0053] In the toothed belt 10, the core wires 13 may be made of two types of yarn, S-twisted yarn and Z-twisted yarn, arranged in a double helix pattern so that they alternate in the belt width direction. In this case, it is suitable for suppressing shifting of the toothed belt 10 when it is running. The core wire 13 may be composed solely of S-twisted yarn or solely of Z-twisted yarn.

[0054] <Tooth covering material> The tooth covering material 14 is attached to the inner surface of the belt body 11 where multiple tooth rubber portions 11b are provided. Therefore, the tooth rubber portion 11b of each belt tooth 12 is covered with the tooth covering material 14. This prevents direct contact between the thermoplastic elastomer composition constituting the tooth rubber portion 11b and 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 of the toothed belt 10, it is preferable that the tooth covering material 14 be made of a resin film. Examples of the resin film material include polyamide (nylon) and polyester. In this case, the tooth covering material 14 can be bonded to the belt body 11 by heat fusion, so the bonding treatment that is performed on the tooth covering material made of a fibrous material to increase the adhesion strength to the belt body 11 becomes unnecessary. Among resin films, polyamide films (nylon films) in which polyamide is the resin component are more preferred. Because polyamide film has a low coefficient of friction, it generates less frictional energy and is less prone to wear. Since polyamide film has a high melting point, even if the temperature of the contact area with the pulley rises, it is less likely to cause rapid wear due to the melting of the polyamide. Therefore, the tooth coating material 14 made of polyamide film can effectively contribute to the low dust generation of the toothed belt 10.

[0056] Examples of polyamides (nylons) that make up the above polyamide film include nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 1212, nylon 6T, and the like. Commercially available polyamides may be used as the above-mentioned polyamides. Examples of such commercially available polyamides include the Leona® series manufactured by Asahi Kasei Corporation.

[0057] The above polyamide film may consist solely of polyamide, or it may contain other components. The polyamide film preferably contains granular wear modifier as another component. The polyamide film comprises a matrix made of polyamide and granular wear modifier dispersed in this matrix, and it is more preferable that the granular wear modifier is exposed on the inner surface of the belt. In this case, the granular wear modifier contributes to reducing the coefficient of friction of the inner surface of the belt. Since the frictional energy received by the inner surface of the belt is reduced, the progression 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 less prone to deformation.

[0058] Examples of materials for the above-mentioned granular wear modifiers include fluororesins such as polytetrafluoroethylene (PTFE), perfluoroalkoxyalkanes (PFA), perfluoroethylene propene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF), as well as ultra-high molecular weight polyethylene (UHMWPE) with a weight-average molecular weight of 1 million or more. These granular wear modifiers, made from these materials, may be used individually or in combination of two or more types.

[0059] The polyamide film described above more preferably 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 wear modifiers and lower the coefficient of friction of the tooth coating material 14. By incorporating these particles and reducing the coefficient of friction of the tooth coating material 14 (i.e., the coefficient of friction of the belt tooth surface), the above-mentioned effects can be achieved.

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

[0061] The average particle size of the above UHMWPE particles is preferably 10 to 65 μm. If the average particle size is less than 10 μm, the amount of UHMWPE particles exposed on the surface of the belt teeth 12 is small, which may result in a poor effect of incorporating them into the polyamide film. On the other hand, if the average particle size exceeds 65 μm, the particles may fall off the surface of the belt during use. The average particle size of the UHMWPE particles mentioned above was measured using a laser diffraction particle size distribution analyzer. Commercially available UHMWPE particles may be used as described above.

[0062] The average particle size of the PTFE particles described above is preferably 10 to 30 μm. If the average particle size is less than 10 μm, the amount of PTFE particles exposed 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, if the average particle size exceeds 30 μm, the particles may fall off the surface of the belt during use. The average particle size of the PTFE particles mentioned above was measured using a laser diffraction type particle size distribution analyzer. Commercially available PTFE particles may be used as described above. Examples of such commercially available products include Fluon® PTFE L150J and Fluon PTFE L169J from AGC Inc., and Algoflon® L100 from Solvey Inc.

[0063] Preferably, the granular wear modifier is exposed to a total of 1-15% of the surface of the tooth coating material 14 that constitutes the inner circumference of the belt. If the amount of exposure of the tooth coating material 14 on the surface is less than 1%, the effect of lowering the coefficient of friction on the surface of the belt teeth 12 is poor. On the other hand, if the amount of exposure exceeds 15%, the adhesion between the tooth coating material 14 and the thermoplastic elastomer composition constituting the tooth rubber portion 11b may be inhibited by the granular wear modifier interposed between them.

[0064] The percentage of granular wear modifier exposed on the surface of the tooth covering material 14 is calculated by observing the surface of the tooth covering material 14 with an optical microscope and determining the ratio of the area of ​​the granular wear modifier to the total surface area of ​​the tooth covering material 14.

[0065] The amount of granular wear modifier exposed on the belt surface (i.e., the surface of the tooth coating material 14) can be adjusted by changing the concentration or dispersion state of the granular wear modifier contained in the polyamide film that makes up the tooth coating material 14. Alternatively, it can be adjusted by polishing the surface of the polyamide film containing the granular wear modifier.

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

[0067] <Side members> Each side member 22 is stacked on the end face 11s of the belt body 11. These side members 22 form the belt end face 10s of the toothed belt 10. The side member 22 is made of a sheet having a predetermined thickness. This side member 22 may also be made 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 that is exposed on the end face 11s of the belt body 11. Therefore, as shown in Figure 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 Figure 1, the entire end face 11s of the belt body 11 is covered by the side member 22, but it is sufficient that at least the core wires 13 exposed on the end face 11s of the belt body 11 are covered by this side member 22.

[0069] The side member 22 is preferably made of a polyamide resin composition or a thermoplastic elastomer composition. Both the polyamide resin composition and the thermoplastic elastomer composition are thermoplastic. Therefore, by making the side member 22 of a polyamide resin composition or a thermoplastic elastomer composition, the side member 22 can be bonded to the end face 11s of the belt body 11 by heat fusion. This toothed belt 10 allows the end face 11s of the belt body 11 to be easily covered with the side member 22. If the side member 22 is made 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 that constitutes the back rubber portion 11a or the tooth rubber portion 11b described above. From the viewpoint of enabling the side member 22 to adhere firmly 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 that constitutes the back rubber portion 11a or the tooth rubber portion 11b described above. In this case, from the viewpoint of low dust generation, it is more preferable that the side member 22 is made of a thermoplastic elastomer composition that does not contain a plasticizer.

[0070] The polyamide resin composition has polyamide as its resin component. Because the polyamide resin composition has a low coefficient of friction, it has low frictional energy and is resistant to wear. The side member 22 may come into contact with the flange of the pulley. Therefore, by making the side member 22 out of a polyamide resin composition, this side member 22 can effectively contribute to the low dust generation of the toothed belt 10. From this viewpoint, it is preferable that the side member 22 be made of a polyamide resin composition.

[0071] Examples of polyamides include nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, and nylon 1212. Among these, nylon 6 and nylon 66 are preferred from the viewpoint of abrasion resistance and low cost. Commercially available polyamides may be used as the above-mentioned polyamides. Examples of such commercially available polyamides include the Leona® series manufactured by Asahi Kasei Corporation.

[0072] If the side member 22 is made of a polyamide resin composition, the polyamide resin composition may consist only of polyamide, or it 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, and antifungal agents.

[0073] Next, a method for manufacturing the toothed belt 10 according to this embodiment will be described.

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

[0075] <Material preparation process> Elastomer Sheet Prepare a thermoplastic elastomer sheet for the back rubber portion and a thermoplastic elastomer sheet for the tooth rubber portion. Each elastomer sheet can be obtained, for example, by preparing a thermoplastic elastomer composition containing TPAE or TPC, which is an elastomer component, and necessary additives, and then molding it into a sheet by extrusion molding or the like. Alternatively, the thermoplastic elastomer sheet for the back rubber portion and the thermoplastic elastomer sheet for the tooth rubber portion may be molded by co-extrusion. In this case, a laminate of the thermoplastic elastomer sheet for the back rubber portion and the thermoplastic elastomer sheet for the tooth rubber portion is obtained. The elastomer sheet formed in this process may be wound up or supplied directly to the next process.

[0076] ≪Tooth covering material≫ The preparation of the dental covering material 14 will be explained using the case where the dental covering material 14 is made of a polyamide film as an example. The polyamide film is molded into a toothed shape by placing it along a heated mold having recesses in the same shape as the teeth of the toothed belt 10, and pressing a soft elastic body against it from the opposite side of the mold. Alternatively, after extruding a polyamide film by extrusion molding, the film is passed through two rolls having the same tooth shape as the belt's tooth profile, and the film is cooled while forming the tooth shape, thereby producing a polyamide film with a toothed profile. Alternatively, a polyamide film with a toothed pattern can be produced by passing the polyamide film through two heated rolls with toothed patterns. The polyamide film with the tooth marks may then be formed into a cylindrical shape.

[0077] ≪Core wire≫ The core wire 13 is prepared by applying a predetermined twist or bonding treatment to the filament 18. 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 members A sheet made of a thermoplastic elastomer composition or a polyamide resin composition is prepared for forming the side member 22. This sheet is punched out to the shape of the belt end face of the toothed belt 10 to produce a side member sheet.

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

[0080] As shown in Figure 5, a cylindrical shape with teeth is formed on the outer surface of the belt forming die 30. Tooth covering material Place 14 over it, and then wrap a pair of core wires 13 spirally around it. Then, a thermoplastic elastomer sheet 11b' for the tooth rubber portion and a thermoplastic elastomer sheet 11a' for the back rubber portion are wrapped around it in that order. The number of layers of each wrapped sheet may be one or two or more, depending on the dimensions of the belt to be made. Furthermore, if necessary, wrap it with release paper or release film (not shown). This allows the laminate S' to be formed on the belt mold 30.

[0081] <Forming process> A jacket, which has a rubber sleeve 32 on its inner surface and a sealed space between the sleeve 32 and the main body, is placed over the laminate S'. As a result, the rubber sleeve 32 is placed over the laminate S' on the belt mold 30, as shown in Figure 6. High-pressure steam is introduced into the mold 30, which is wrapped around the laminate S', and the space inside the jacket to heat and compress it. This causes the thermoplastic elastomer constituting the thermoplastic elastomer sheets 11a' and 11b' to pass through the gaps between the core wires 13, forming tooth-forming grooves 31, and flowing in, thereby forming belt teeth 12 as shown in Figure 7. In this case, the temperature of the high-pressure steam shall be equal to or higher than the temperature at which the thermoplastic elastomer flows. Furthermore, if 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, the jacket and mold 30 are cooled with water or the like to lower the temperature of the elastomer to below 100°C, and then the mold 30 and molded body S are removed from the jacket. Furthermore, if the temperature of the molded body S is above 40°C, it is cooled further, and once the temperature of the molded body S has dropped below 40°C, the molded body S is removed from the mold 30.

[0083] <Finishing Process> By cutting the removed molded body S to a specified width and separating it, the belt body 11 shown in Figure 8(a) is obtained. After attaching the side member sheet 22' to the end face 11s of the belt body 11, a heating plate is pressed against the side member sheet 22'. The side member sheet 22' is heated and welded to the end face 11s of the belt body 11. This results in the toothed belt 10 shown in Figure 8(b). By following the process described above, a toothed belt 10 can be manufactured in which the belt body 11 is made of a thermoplastic elastomer composition and the core wire 13 is not exposed on the belt end face 10s.

[0084] <Other> If the hardness of the thermoplastic elastomer sheet 11b' for the tooth rubber portion and the thermoplastic elastomer sheet 11a' for the back rubber portion differ, the tooth covering material 14, the core wire 13, and the thermoplastic elastomer sheet 11b' for the tooth rubber portion are laminated on the outer surface of the belt molding die 30, then the belt teeth 12 are formed by heating and compression with high-pressure steam as described above, after which the belt teeth 12 are formed, the belt teeth are cooled, the thermoplastic elastomer sheet 11a' for the back rubber portion is wrapped around it, the belt teeth are heated and compressed with high-pressure steam again, then cooled again, and finally the finishing process is performed to manufacture the toothed belt 10. [Examples]

[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 a tooth profile of S8M was manufactured and its performance was evaluated. The toothed belts of each example were manufactured using the manufacturing method described above. The 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> Thermorun (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> Milacran (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 multiple twist yarn and has been treated with an epoxy-based adhesive.

[0094] (Tooth coating material)​​​​​​​​​A polyamide resin composition was prepared by blending a predetermined amount of UHMWPE particles (Miperon XM-220, manufactured by Mitsui Chemicals, Inc.) with Leona 1500. This composition was then extruded into a sheet to produce a 0.65 mm thick film. The concentration of UHMWPE particles in the polyamide resin composition was 15% by mass. In the preparation of the dental coating material PA2, the surface of the resulting sheet was polished after extrusion to adjust the amount of UHMWPE particle exposure. <Polyamide film PA3> A polyamide resin composition was prepared by blending a predetermined amount of PTFE particles (AGC's "FluonPTFE L150J") with Leona 1500, and then extruded to form a sheet to produce a 0.65 mm thick film. The concentration of PTFE particles in the polyamide resin composition was 20% by mass. In the preparation of the dental coating material PA3, the surface of the obtained sheet was polished after extrusion to adjust the amount of exposed PTFE particles.

[0095] [Example 1] Using the above-mentioned TPAE(A1) for the belt body, which includes the back rubber portion and the tooth rubber portion, the above-mentioned TPAE for the side members, the above-mentioned polyamide film PA1 for the tooth covering material, and the above-mentioned core wire, a toothed belt with a tooth type of S8M was manufactured using the above-described manufacturing method (see Figures 5 to 9). Example 1 does not contain a plasticizer. For durability testing, a toothed belt with a belt width of 8 mm and a belt length of 1200 mm was prepared, and for dust generation 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 end face of the belt. Comparative Example 1 does not have side members. Comparative Example 1 does not contain a plasticizer.

[0098] [Examples 3-4] Toothed belts of Examples 3 and 4 were obtained in the same manner as in Example 1, except that the tooth covering material was as shown in Table 1 below. Examples 3 and 4 do not contain plasticizers. In Example 3, the exposure amount of UHMWPE particles was 10.3%. In Example 4, the exposure amount of PTFE particles was 12.4%.

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

[0100] [Comparative Examples 2-4] The toothed belts of Comparative Examples 2 to 4 were 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 plasticizers.

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

[0102] (Evaluation method) Durability tests were conducted on the toothed belts manufactured in the examples and comparative examples to evaluate their durability, and dust generation tests were conducted to evaluate their dust generation. The results are shown in Table 1.

[0103] <Durability Test> Durability tests are conducted to evaluate durability under standard driving conditions. These tests were performed on toothed belts manufactured in Examples 1-6 and Comparative Examples 2-4. Figure 10 shows the belt running test machine 80 used in durability test 1. The belt-driven test machine 80 comprises a drive 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 located to its right. The driven pulley 82 is provided to be movable from side to side so that it can be subjected to an axial load (dead weight).

[0104] For each of the toothed belts 110 manufactured in Examples 1-6 and Comparative Examples 2-4, the belts were wrapped between the drive pulley 81 and driven pulley 82 of a belt running test machine 80. A axial load of 608 N was applied to the right side of the driven pulley 82 to apply belt tension, and a rotational load of 34.2 N·m was applied to the driven pulley 82. The belt was then run at room temperature with the drive pulley 81 rotating at a speed of 4200 revolutions per minute. The belt running was stopped periodically, and the presence or absence of cracks or other failures on the back of the rubber backing was visually checked. The belt running time until a failure was confirmed was measured. The maximum belt running time was set to 500 hours. Furthermore, if tooth skipping occurred, even if it did not result in a malfunction, the test was terminated at that point.

[0105] <Dust generation evaluation test> The dust generation evaluation test assesses the amount of dust generated during belt operation. This test was performed on toothed belts manufactured in Examples 1-6 and Comparative Example 1. This evaluation follows the method for measuring dust generation from the motion mechanisms of equipment used in cleanrooms, as defined in JIS B9926. Figure 11 shows the belt-running test machine 90 used in the dust generation evaluation test. The belt-running test machine 90 is equipped with a test specimen mounting section 91. Within this test specimen mounting section 91 are a drive 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, located to its right. The driven pulley 93 is provided to be movable from side to side so that an axial load (dead weight) can be applied. A blower unit 94 is provided upstream of the test specimen installation section 91. Outside air is drawn in by this blower unit 94. An air filter unit 95 is provided downstream of the blower unit 94. Clean air is introduced into the test specimen installation section 91 as the outside air passes through this air filter unit 95. The air that passes through the test specimen installation section 91 is released to the outside through the measurement section 96. A dust generation sensor (not shown) is installed in this measurement section 96, and the amount of dust generated 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, the belts were wrapped between the drive pulley 92 and the driven pulley 93 of the belt running test machine 90, and a shaft load of 687 N was applied to the right of the driven pulley 93 to apply belt tension. The belts were then run at room temperature by rotating the drive pulley 92 at a rotational speed of 200 revolutions per minute. The dust generation capacity was then evaluated by comparing the average value per minute of cumulative dust generation when the toothed belt was run for 10 minutes.

[0107] [Table 1]

[0108] [Table 2]

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

[0110] The present invention is useful in the field of toothed belts in which a highly plastic elastomer composition is used as the material for the tooth rubber portion and the back rubber portion. [Explanation of Symbols]

[0111] 10, 110, 120 toothed belt 10s Toothed belt 10 belt end face 11 Belt body 11s End face of belt body 11 11a Back elastic section 11b Tooth rubber part 12 belt teeth 13 Core wires 14 Tooth covering material 15. Root of the tooth 16 yarns 17 Strand 18 filaments 22 Side members 30 Belt forming mold 31 Tooth formation groove 32 Rubber sleeves 80, 90 Testing Machines 81, 92 Drive pulley 82, 93 Driven pulley 91 Test specimen installation section 94 Air blower 95 Air filter section 96 Measuring part

Claims

1. A belt body having a flat, strip-shaped back rubber portion and a plurality of tooth rubber portions disposed on the inner circumference side of the back rubber portion, each integrally provided with the back rubber portion to form belt teeth, wherein both the back rubber portion and the tooth rubber portions are made of a thermoplastic elastomer composition, A core wire is embedded in the inner circumference portion of the back rubber part, arranged to form a spiral with a pitch in the belt width direction, A tooth covering material that covers the plurality of toothed rubber portions provided on the inner circumference side of the belt body, The side members are laminated on the end face of the belt body and form the end face of the belt. Equipped with, The elastomer component of the thermoplastic elastomer composition constituting the back rubber portion and the tooth rubber portion 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 portion is 25 to 70. The hardness of the thermoplastic elastomer composition constituting the tooth rubber portion is 40 to 70, and is greater than or equal to the hardness of the thermoplastic elastomer composition constituting the back rubber portion. The tooth covering material is made of a polyamide film. The side member is a sheet or film made of a molded product of a polyamide resin composition or a thermoplastic elastomer composition. The aforementioned core wire includes carbon filaments made of carbon fibers and is not exposed on the belt end face, and is a toothed belt.

2. The aforementioned core wire is exposed on the end face of the belt body, The side member covers the core wire exposed on the end face of the belt body. The toothed belt according to claim 1.

3. The side member is directly attached to the end face of the belt body. The toothed belt according to claim 1 or 2.

4. The aforementioned elastomer component is a polyamide thermoplastic elastomer (TPAE), The soft segment of the elastomer component has a polyether structure. A toothed belt according to any one of claims 1 to 3.

5. The polyamide film comprises a matrix made of polyamide and a granular wear modifier dispersed in the matrix. The granular wear modifier is exposed on the inner surface of the belt. The granular wear modifier is made of ultra-high molecular weight polyethylene (UHMWPE) particles. A toothed belt according to any one of claims 1 to 4.

6. The side member is made of a thermoplastic elastomer composition. The thermoplastic elastomer composition constituting the side member is the same as the thermoplastic elastomer composition constituting the tooth rubber portion. A toothed belt according to any one of claims 1 to 5.

7. The elastomer component of the thermoplastic elastomer composition constituting the side member and the tooth rubber portion is a polyamide-based thermoplastic elastomer (TPAE). The toothed belt according to claim 6.

8. The back rubber portion or the tooth rubber portion is made of a thermoplastic elastomer composition that does not contain a plasticizer. A toothed belt according to any one of claims 1 to 7.

9. The thermoplastic elastomer composition constituting the back rubber portion and the thermoplastic elastomer composition constituting the tooth rubber portion are the same. A toothed belt according to any one of claims 1 to 8.

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