Toothed belt

Abstract

This toothed belt (B) is provided with a belt main body (11) that has a flat band rubber part (111) and a plurality of tooth rubber parts (112). Each of the plurality of tooth rubber parts (112) is formed of a rubber composition which is obtained by crosslinking an uncrosslinked rubber composition that contains a chloroprene rubber, ethylene glycol dimethacrylate, and an organic peroxide.

Description

Toothed belt

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

[0002] A toothed belt is known in which the belt body is formed of a rubber composition having chloroprene rubber as a rubber component. For example, Patent Document 1 discloses using chloroprene rubber as the rubber component of the rubber composition forming the belt body of the toothed belt.

[0003] Japanese Patent No. 6652688

[0004] The present invention is a toothed belt provided with a belt body having a flat belt rubber portion and a plurality of tooth rubber portions arranged at a predetermined pitch in the length direction on one surface of the flat belt rubber portion, and each of the plurality of tooth rubber portions is formed of a rubber composition obtained by crosslinking an uncrosslinked rubber composition containing chloroprene rubber, ethylene glycol dimethacrylate, and an organic peroxide.

[0005] Perspective view of one piece of the toothed belt according to the embodiment. Front view in the direction of arrow X in FIG. 1A. Cross-sectional view taken along IC-IC (for two teeth) in FIG. 1B. Cross-sectional view of a part of the belt molding die. First explanatory view of the manufacturing method of the toothed belt according to the embodiment. Second explanatory view of the manufacturing method of the toothed belt according to the embodiment. Third explanatory view of the manufacturing method of the toothed belt according to the embodiment. Diagram showing the pulley layout of the skip torque measuring device.

[0006] FIGS. 1A to C show a toothed belt B according to the embodiment. This toothed belt B is an endless meshing transmission belt used, for example, in automobiles, motorcycles, general industrial machines, etc.

[0007] The toothed belt B according to the embodiment has a plurality of tooth portions 10A. The plurality of tooth portions 10A are arranged at a predetermined pitch P in the belt length direction and are each formed so as to project toward the inner peripheral side of the belt. Also, between a pair of adjacent tooth portions 10A, a tooth bottom portion 10B is formed.

[0008] The teeth 10A are so-called round teeth with a semicircular cross-sectional shape, but they may also be of other shapes, such as trapezoidal teeth with a trapezoidal cross-sectional shape. The teeth 10A may be composed of protrusions formed to extend in the belt width direction, or they may be so-called serrated teeth composed of protrusions formed to extend in a direction inclined with respect to the belt width direction.

[0009] The belt length (circumference along the belt pitch line L) of the toothed belt B according to this embodiment is, for example, 225 mm or more and 6000 mm or less. The belt width is, for example, 10 mm or more and 120 mm or less. The maximum belt thickness is, for example, 2 mm or more and 9.5 mm or less.

[0010] The pitch P of the teeth 10A is, for example, 3 mm to 14 mm. The height of the teeth 10A is, for example, 1 mm to 6.5 mm. This height of the teeth 10A is defined by the distance from the tooth root 10B to the tip of the teeth 10A. The width of the teeth 10A is, for example, 1.5 mm to 9.5 mm. This width of the teeth 10A is defined by the distance between the ends of a pair of adjacent tooth roots 10B that sandwich the teeth 10A in the belt length direction.

[0011] The toothed belt B according to this embodiment comprises a belt body 11, a core wire 12, and a reinforcing fabric 13.

[0012] The belt body 11 has a flat rubber portion 111 and a plurality of toothed rubber portions 112. The plurality of toothed rubber portions 112 are arranged on the inner circumferential surface of the flat rubber portion 111 at predetermined intervals in the longitudinal direction. The belt body 11 is formed of a rubber composition X which is formed by heating and pressurizing an uncrosslinked rubber composition X' containing chloroprene rubber (hereinafter referred to as "CR"), a co-crosslinking agent ethylene glycol dimethacrylate, and a crosslinking agent organic peroxide. Therefore, the flat rubber portion 111 and the plurality of toothed rubber portions 112 are integrally formed from the rubber composition X.

[0013] The CR contained in the uncrosslinked rubber composition X' is the main component of the rubber component. The CR content in the rubber component is preferably 90% by mass or more, and more preferably 100% by mass, from the viewpoint of obtaining high strength of the tooth portion 10A, as will be described later. The uncrosslinked rubber composition X' may also contain other rubber components besides CR, such as hydrogenated nitrile rubber (H-NBR), ethylene-α-olefin elastomer (e.g., EPDM or EPR).

[0014] Examples of CR include sulfur-modified CR, mercaptan-modified CR, and xanthogene-modified CR. It is preferable that the CR contains one or more of these, and it is more preferable that it contains sulfur-modified CR from the viewpoint of obtaining high strength of the tooth portion 10A.

[0015] From the viewpoint of obtaining high strength of the tooth portion 10A, the content of ethylene glycol dimethacrylate in the uncrosslinked rubber composition X' is preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass, per 100 parts by mass of CR.

[0016] From the viewpoint of obtaining high strength of the tooth portion 10A, the uncrosslinked rubber composition X' preferably contains a cocrosslinking agent other than ethylene glycol dimethacrylate. Examples of cocrosslinking agents other than ethylene glycol dimethacrylate include N,N'-m-phenylenedimaleimide, zinc dimethacrylate, trimethylolpropane trimethacrylate, triallyl isocyanurate, and liquid polybutadiene. The uncrosslinked rubber composition X' preferably contains one or more of these, and from the same viewpoint as above, it is more preferable to contain N,N'-m-phenylenedimaleimide and / or zinc dimethacrylate, and even more preferable to contain both N,N'-m-phenylenedimaleimide and zinc dimethacrylate.

[0017] If the uncrosslinked rubber composition X' contains N,N'-m-phenylenedimaleimide, the content of N,N'-m-phenylenedimaleimide in the uncrosslinked rubber composition X' is preferably 3 to 15 parts by mass, more preferably 6 to 10 parts by mass, per 100 parts by mass of CR, from the viewpoint of obtaining high strength of the tooth portion 10A. From the same viewpoint, the mass ratio of the N,N'-m-phenylenedimaleimide content in the uncrosslinked rubber composition X' to the ethylene glycol dimethacrylate content is preferably 0.5 to 2, more preferably 0.6 to 1.8.

[0018] If the uncrosslinked rubber composition X' contains zinc dimethacrylate, the zinc dimethacrylate content in the uncrosslinked rubber composition X' is preferably 5 to 25 parts by mass, more preferably 10 to 20 parts by mass, per 100 parts by mass of CR, from the viewpoint of obtaining high strength of the tooth portion 10A. The mass ratio of the zinc dimethacrylate content in the uncrosslinked rubber composition X' to the ethylene glycol dimethacrylate content is preferably 1 to 5, more preferably 1.5 to 4.5, from the same viewpoint. From the same viewpoint, it is preferable that the zinc dimethacrylate content in the uncrosslinked rubber composition X' is greater than the ethylene glycol dimethacrylate content.

[0019] When the uncrosslinked rubber composition X' contains both N,N'-m-phenylenedimaleimide and zinc dimethacrylate, the sum of the N,N'-m-phenylenedimaleimide and zinc dimethacrylate content in the uncrosslinked rubber composition X' is preferably 10 to 35 parts by mass, more preferably 15 to 30 parts by mass, per 100 parts by mass of CR, from the viewpoint of obtaining high strength of the tooth portion 10A. From the same viewpoint, the mass ratio of the N,N'-m-phenylenedimaleimide content in the uncrosslinked rubber composition X' to the zinc dimethacrylate content is preferably 0.2 or more and less than 1, more preferably 0.3 or more and 0.9. From the same viewpoint, the N,N'-m-phenylenedimaleimide content in the uncrosslinked rubber composition X' is preferably less than the zinc dimethacrylate content.

[0020] Examples of organic peroxides include dialkyl peroxides, peroxyketals, and peroxyesters. Examples of dialkyl peroxides include dicumyl peroxide, 1,3-di(t-butylperoxy)diisopropylbenzene, 1,4-di(t-butylperoxy)diisopropylbenzene, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane-3. Examples of peroxyketals include 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, and n-butyl-4,4-di(t-butylperoxy)valerate. Examples of peroxyesters include 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-hexylperoxybenzoate, and t-butylperoxybenzoate. The organic peroxide preferably contains one or more of these, and more preferably contains dialkyl peroxide from the viewpoint of obtaining high strength of the tooth portion 10A, and even more preferably contains 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

[0021] From the viewpoint of obtaining high strength of the tooth portion 10A, the content of organic peroxide in the uncrosslinked rubber composition X' is preferably 1 to 5 parts by mass, more preferably 2.5 to 3.5 parts by mass, per 100 parts by mass of CR.

[0022] The uncrosslinked rubber composition X' may contain carbon black. Examples of carbon black include channel black, furnace black, thermal black, and acetylene black. Examples of furnace black include SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234. Examples of thermal black include FT and MT. The carbon black preferably contains one or more of these, and from the viewpoint of obtaining high strength of the tooth portion 10A, it is more preferable to contain carbon black with an average particle diameter of 30 nm or less, and even more preferable to contain HAF. From the same viewpoint, the carbon black content in the uncrosslinked rubber composition X' is preferably 35 parts by mass or more and 70 parts by mass or less, more preferably 45 parts by mass or more and 55 parts by mass or less, per 100 parts by mass of CR.

[0023] The uncrosslinked rubber composition X' may also contain other materials such as antioxidants and inorganic fillers.

[0024] The Mooney viscosity of the uncrosslinked rubber composition X' is preferably 40 MS (1+4) 100°C or higher and 80 MS (1+4) 100°C or lower, and more preferably 45 MS (1+4) 100°C or higher and 70 MS (1+4) 100°C or lower, from the viewpoint of obtaining high strength of the tooth portion 10A and excellent belt moldability. This Mooney viscosity is measured in accordance with JIS K6300-1:2013.

[0025] For the rubber composition X formed by crosslinking the uncrosslinked rubber composition X', the tensile stress S at 20% elongation in the grain direction at 100°C is... ２０ The tensile stress S at 20% elongation in the direction of the teeth at 100°C is preferably 8 MPa or higher, more preferably 10 MPa or higher, and even more preferably 14 MPa or higher, from the viewpoint of obtaining high strength of the teeth 10A. ２０ This is determined from the test results of a tensile test conducted on a test specimen with the grain direction as the length direction, after exposure to a 100°C atmosphere for 30 minutes, in accordance with JIS K6251:2017.

[0026] The hardness of the rubber composition X is preferably 71HsJIS C or higher and 90HsJIS C or lower, and more preferably 75HsJIS C or higher and 85HsJIS C or lower, from the viewpoint of obtaining high strength of the teeth portion 10A. The hardness of this rubber composition X is measured on the externally exposed portion of the belt body 11 of the toothed belt B using a spring-type hardness tester type C in accordance with JIS K6301-1995.

[0027] The core wire 12 is embedded in the inner circumference portion of the flat rubber band 111 of the belt body 11 and is arranged to form a spiral with a pitch in the belt width direction. The outer diameter of the core wire 12 is, for example, 0.15 mm or more and 0.80 mm or less.

[0028] The core wire 12 is composed of twisted yarn such as glass fiber, aramid fiber, carbon fiber, or metal fiber. Preferably, the core wire 12 is provided with S-twisted yarn and Z-twisted yarn forming a double helix, but it may also be provided with only a single S-twisted yarn or a Z-twisted yarn. Preferably, the core wire 12 is subjected to at least one of the following bonding treatments for bonding with the belt body 11: RFL treatment, which involves immersion in a so-called RFL aqueous solution followed by heating, and rubber adhesive treatment, which involves immersion in rubber adhesive followed by drying. The core wire 12 may be subjected to a pre-treatment before the bonding treatment, which involves immersion in an epoxy solution or isocyanate solution followed by heating.

[0029] The reinforcing fabric 13 is provided to cover the side of the belt body 11 where the multiple toothed rubber portions 112 are located. The tooth portion 10A is constructed by covering each of the multiple toothed rubber portions 112 of the belt body 11 with this reinforcing fabric 13. At the tooth base portion 10B, the core wire 12 embedded in the inner circumference portion of the flat rubber band portion 111 of the belt body 11 is positioned immediately inside this reinforcing fabric 13.

[0030] The reinforcing fabric 13 is made of a woven fabric, knitted fabric, nonwoven fabric, etc., formed from yarns such as nylon fibers (aliphatic polyamide fibers), polyester fibers, aramid fibers (aromatic polyamide fibers), or cotton. Preferably, the reinforcing fabric 13 has elasticity, such as a woven fabric in which woolly processed yarn is used for the weft yarn extending in the length direction of the belt. Preferably, the reinforcing fabric 13 is subjected to one or more adhesive treatments from among RFL treatment, in which it is immersed in an RFL aqueous solution and then heated; soaking treatment, in which it is immersed in a low-viscosity rubber glue and then dried; and coating treatment, in which a high-viscosity rubber glue is applied to the surface on the belt body 11 side and dried. The reinforcing fabric 13 may also be subjected to a pre-treatment before the adhesive treatment, in which it is immersed in an epoxy solution or isocyanate solution and then heated.

[0031] According to the toothed belt B of the embodiment described above, the toothed rubber portion 112 of the belt body 11 is formed of a rubber composition X in which an uncrosslinked rubber composition X' containing CR, ethylene glycol dimethacrylate, and an organic peroxide is crosslinked, thereby achieving high strength of the teeth 10A. This is thought to be because the CR is crosslinked by the organic peroxide and a crosslinked structure is formed by ethylene glycol dimethacrylate, thereby increasing its hardness. As a result, high durability against so-called tooth chipping can be obtained.

[0032] Next, a method for manufacturing a toothed belt B according to an embodiment will be described with reference to Figures 2 and 3A to 3C. The method for manufacturing a toothed belt B according to an embodiment includes a material preparation step, a molding step, a crosslinking step, and a finishing step.

[0033] <Material Preparation Process> An uncrosslinked rubber composition X' is prepared by kneading a rubber component containing CR, and then adding and kneading various rubber compounding agents containing ethylene glycol dimethacrylate and organic peroxides. This uncrosslinked rubber composition X' is processed into an uncrosslinked rubber composition sheet 11' by calendering. The core wire 12 is subjected to a contact treatment. After the reinforcing fabric 13 is subjected to a contact treatment, it is formed into a cylindrical shape.

[0034] <Molding Process> Figure 2 shows a belt forming die 20. This belt forming die 20 is cylindrical and has an outer circumferential surface on which a plurality of tooth-forming grooves 21, each formed to extend in the axial direction, are arranged at intervals in the circumferential direction.

[0035] As shown in Figure 3A, a cylindrical reinforcing cloth 13 is placed over the outer surface of the belt molding die 20, and the core wire 12 is wound spirally over it. An uncrosslinked rubber composition sheet 11' is then wound over it, and an uncrosslinked slab S' is formed on the belt molding die 20. It is preferable that the uncrosslinked rubber composition sheet 11' be arranged so that its row direction corresponds to the belt length direction.

[0036] <Crosslinking Process> As shown in Figure 3B, a rubber sleeve 22 is placed over the uncrosslinked slab S' on the belt mold 20, and it is placed inside a vulcanizing can and sealed. High-temperature and high-pressure steam is then filled into the vulcanizing can and held there for a predetermined time. At this time, the uncrosslinked slab S' is pressed against the belt mold 20 and heated, causing the uncrosslinked rubber composition X' constituting the uncrosslinked rubber composition sheet 11' to flow into each of the multiple tooth-forming grooves 21 of the belt mold 20, passing between the core wires 12 and pressing against the reinforcing fabric 13, and crosslinking occurs. If the viscosity of the uncrosslinked rubber composition X' is high, its flow into the tooth-forming grooves 21 will be insufficient, and the teeth 10A will have defects and will not be formed in a complete shape. However, because the main component of the rubber component in the uncrosslinked rubber composition X' is low-viscosity CR, the flow of the uncrosslinked rubber composition X' into the tooth-forming grooves 21 is smooth, and teeth 10A with a complete shape without defects can be formed. At the same time, the core wire 12 and the reinforcing fabric 13 are combined and integrated, and finally, as shown in Figure 3C, a cylindrical belt slab S is formed on the belt molding die 20.

[0037] <Finishing Process> The inside of the vulcanizing can is depressurized to release the seal, the belt slab S formed between the belt molding die 20 and the rubber sleeve 22 is removed and demolded, and the toothed belt B according to the embodiment is obtained by cutting it into rings of a predetermined width.

[0038] In the above embodiment, the flat rubber portion 111 and the toothed rubber portion 112 of the belt body 11 are formed from the same rubber composition X. However, the embodiment is not limited to this, and the toothed rubber portion 112 may be formed from the rubber composition X, and the flat rubber portion 111 may be formed from a different rubber composition.

[0039] (Toothed Belts) Toothed belts were prepared according to the following Examples 1 to 5 and Comparative Examples. The composition of the uncrosslinked rubber composition used in the preparation of each is also shown in Table 1.

[0040] <Example 1> Sulfur-modified CR rubber component was placed in the chamber of a sealed Banbury mixer and kneaded. Then, per 100 parts by mass of this sulfur-modified CR, 48 parts by mass of carbon black HAF (Seas 3, manufactured by Tokai Carbon Co., Ltd., average particle size: 28 nm), 4.2 parts by mass of antioxidant, 10 parts by mass of ethylene glycol dimethacrylate (Light Ester EG, manufactured by Kyoeisha Chemical Co., Ltd.), 8 parts by mass of N,N'-m-phenylenedimaleimide (Barnock PM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 20 parts by mass of zinc dimethacrylate (Actor ZMA, manufactured by Kawaguchi Chemical Industry Co., Ltd.), 4 parts by mass of magnesium oxide (Kyowa Mag 150, manufactured by Kyowa Chemical Industry Co., Ltd.), and an organic peroxide-containing material (Perhexa 25B-40) containing 40% by mass of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane was added. An uncrosslinked rubber composition was obtained by adding and kneading 7.3 parts by mass (organic peroxide: 2.92 parts by mass) (manufactured by NOF Corporation).

[0041] A toothed belt with the same configuration as the above embodiment was prepared by forming the belt body with a rubber composition obtained by crosslinking the uncrosslinked rubber composition, and this was designated as Example 1. A twisted yarn of bonded glass fibers was used for the core wire. A woven fabric of bonded nylon 6,6 fibers was used for the reinforcing fabric. The toothed belt of Example 1 had a belt circumference of 1248 mm, a belt width of 100 mm, and a tooth pitch of 8 mm.

[0042] <Examples 2-5> In Example 2, the composition was the same as in Example 1, except that the amount of ethylene glycol dimethacrylate was 5 parts by mass per 100 parts by mass of sulfur-modified CR.

[0043] In Example 3, the same configuration as in Example 2 was used, except that the compounding amount of zinc dimethacrylate was 10 parts by mass with respect to 100 parts by mass of sulfur-modified CR.

[0044] In Example 4, the same configuration as in Example 2 was used, except that the compounding amount of HAF was 60 parts by mass with respect to 100 parts by mass of sulfur-modified CR and zinc dimethacrylate was not compounded.

[0045] In Example 5, the same configuration as in Example 1 was used, except that the compounding amount of ethylene glycol dimethacrylate was 15 parts by mass with respect to 100 parts by mass of sulfur-modified CR.

[0046] <Comparative Example> In the comparative example, the same configuration as in Example 1 was used, except that an unvulcanized rubber composition containing 80 parts by mass of carbon black HAF, 4.5 parts by mass of an antioxidant, 5 parts by mass of N,N'-m-phenylenedimaleimide, 6.5 parts by mass of magnesium oxide, 4.6 parts by mass of a vulcanization accelerator, and 5 parts by mass of zinc oxide was used with respect to 100 parts by mass of sulfur-modified CR.

[0047]

[0048] (Test method and results) The following tests were conducted. The results are shown in Table 1.

[0049] <Mooney viscosity> The Mooney viscosity of the unvulcanized rubber composition used in the production of each of Examples 1 to 5 and the comparative example was measured based on JIS K6300-1:2013.

[0050] <20% modulus> The unvulcanized rubber composition used in the production of each of Examples 1 to 5 and the comparative example was heated and pressurized to be vulcanized to form a sheet-like rubber composition, and a dumbbell-shaped test piece with the grain direction as the length direction was punched out therefrom. Based on JIS K6251:2017, after exposing the test piece in a temperature atmosphere of 100°C for 30 minutes, a tensile test was conducted, and the tensile stress S ２０ at 20% elongation in the grain direction at 100°C, which is the 20% modulus, was determined from the test results.

[0051] <Hardness> The hardness of the externally exposed portion of the belt body of each of Examples 1 to 5 and the Comparative Example was measured using a spring-type hardness tester (Type C) in accordance with JIS K6301-1995.

[0052] <Skip Torque> Figure 4 shows a skip torque measuring device 30. This skip torque measuring device 30 has a drive pulley 31 with 22 teeth and a driven pulley 32 with 33 teeth, which are spaced apart in the lateral direction. The driven pulley 32 is movably mounted in the lateral direction.

[0053] For each of the toothed belts B in Examples 1 to 5 and the Comparative Example, the belts were wrapped around the drive pulley 31 and driven pulley 32 of the skip torque measuring device 30 at room temperature (25°C). The driven pulley 32 was moved laterally to a position where a belt tension of 150 N was applied to the toothed belt B and then fixed in place. The driven pulley 32 was then locked to prevent rotation, while the drive pulley 31 was rotated at 1 rpm. The drive shaft torque at which tooth skipping occurred on the drive pulley 31 was measured, and the peak value was defined as the skip torque. The magnitude of this skip torque correlates with the strength of the teeth.

[0054] This invention is useful in the field of toothed belts.

[0055] B Toothed belt S' Uncrosslinked slab S Belt slab 10A Tooth portion 10B Tooth root portion 11 Belt body 11' Uncrosslinked rubber composition sheet 111 Flat rubber strip portion 112 Tooth rubber portion 12 Core wire 13 Reinforcement fabric 20 Belt molding die 21 Tooth forming groove 22 Rubber sleeve 30 Skip torque measuring device 31 Drive pulley 32 Driven pulley

Claims

1. A toothed belt comprising a belt body having a flat rubber band portion and a plurality of toothed rubber portions arranged at predetermined intervals in the longitudinal direction on one side surface of the flat rubber band portion, wherein each of the plurality of toothed rubber portions is formed of a crosslinked rubber composition containing chloroprene rubber, ethylene glycol dimethacrylate, and an organic peroxide.

2. A toothed belt according to claim 1, wherein the chloroprene rubber comprises sulfur-modified chloroprene rubber.

3. A toothed belt according to claim 1 or 2, wherein the content of the ethylene glycol dimethacrylate in the uncrosslinked rubber composition is 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the chloroprene rubber.

4. A toothed belt according to any one of claims 1 to 3, wherein the organic peroxide comprises a dialkyl peroxide.

5. A toothed belt according to any one of claims 1 to 4, wherein the content of the organic peroxide in the uncrosslinked rubber composition is 1 part by mass or more and 5 parts by mass or less per 100 parts by mass of the chloroprene rubber.

6. A toothed belt according to any one of claims 1 to 5, wherein the uncrosslinked rubber composition contains N,N'-m-phenylenedimaleimide.

7. A toothed belt according to claim 6, wherein the content of N,N'-m-phenylenedimaleimide in the uncrosslinked rubber composition is 3 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the chloroprene rubber.

8. A toothed belt according to claim 6 or 7, wherein the mass ratio of the content of N,N'-m-phenylenedimaleimide in the uncrosslinked rubber composition to the content of ethylene glycol dimethacrylate is 0.5 or more and 2 or less.

9. A toothed belt according to any one of claims 6 to 8, wherein the uncrosslinked rubber composition further contains zinc dimethacrylate.

10. A toothed belt according to claim 9, wherein the content of zinc dimethacrylate in the uncrosslinked rubber composition is 5 parts by mass or more and 25 parts by mass or less per 100 parts by mass of chloroprene rubber.

11. A toothed belt according to claim 9 or 10, wherein the mass ratio of the content of zinc dimethacrylate in the uncrosslinked rubber composition to the content of ethylene glycol dimethacrylate is 1 or more and 5 or less.

12. A toothed belt according to any one of claims 9 to 11, wherein the content of zinc dimethacrylate in the uncrosslinked rubber composition is greater than the content of ethylene glycol dimethacrylate.

13. A toothed belt according to any one of claims 9 to 12, wherein the sum of the content of N,N'-m-phenylenedimaleimide and zinc dimethacrylate in the uncrosslinked rubber composition is 10 parts by mass or more and 35 parts by mass or less per 100 parts by mass of chloroprene rubber.

14. A toothed belt according to any one of claims 9 to 13, wherein the content of N,N'-m-phenylenedimaleimide in the uncrosslinked rubber composition is less than the content of zinc dimethacrylate.

15. A toothed belt according to claim 14, wherein the mass ratio of the content of N,N'-m-phenylenedimaleimide in the uncrosslinked rubber composition to the content of zinc dimethacrylate is 0.2 or more and less than 1.

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