WO2023021808A1

WO2023021808A1 - Toothed belt

Info

Publication number: WO2023021808A1
Application number: PCT/JP2022/021898
Authority: WO
Inventors: 武将吉見; 貴光明石; 隆西川
Original assignee: バンドー化学株式会社
Priority date: 2021-08-18
Filing date: 2022-05-30
Publication date: 2023-02-23
Also published as: JPWO2023021808A1

Abstract

The present invention addresses the problem of providing a toothed belt excellent in durability of a tooth rubber portion.　As a solving means, provided is a toothed belt comprising: a belt body which comprises a back rubber portion having a flat belt shape and a plurality of tooth rubber portions provided to a surface on one side of the back rubber portion and which is formed from a rubber composition containing H-NBR as a main component; a core strand embedded in the back rubber portion; and a tooth reinforcement fabric which coats a surface on the side provided with the plurality of tooth rubber portions. The tooth reinforcement fabric uses aramid-based fibers as the warp yarns (yarns extending in the belt width direction) and uses, as the weft yarns (yarns extending in the belt circumferential direction), composite yarns made from polyurethane-based fibers as the core yarns and aramid-based fibers and woolly nylon fibers as the cover yarns.

Description

toothed belt

The present invention relates to toothed belts.

A toothed belt is used as one of the methods for transmitting power. A toothed belt generally has a flat belt-like back rubber portion and a plurality of tooth rubber portions provided on one side surface of the back rubber portion, and includes a toothed belt main body formed from a rubber composition. , a core wire embedded in the back rubber portion, and a tooth portion reinforcing cloth at least partially embedded in the surface on the inner peripheral side where the tooth rubber portion is provided (Patent Document 1, etc.).
Since the toothed belt transmits rotation while the belt teeth and the tooth profile provided on the pulley mesh with each other, it is suitable for applications requiring synchronous transmission and positional accuracy.

In recent years, with the increase in output and performance of industrial machinery, there is a demand for toothed belts that can handle high loads. A toothed belt tends to skip (a phenomenon in which the belt teeth and pulley teeth do not mesh and the belt teeth run over the pulley teeth) when operated under high load conditions. If the skip occurs, the belt teeth may be damaged. If the belt teeth of the toothed belt are damaged, accurate power transmission cannot be performed.
As a toothed belt with improved durability of the tooth rubber portion, Patent Literature 1 proposes a toothed belt suitable for high-torque transmission applications, which has nonwoven fabric and woven or knitted fabric as reinforcing fabrics.

WO2016/047052

An object of the present invention is to provide a toothed belt having a tooth rubber portion with excellent durability.

The configuration of the present invention for solving the above problems is as follows.
1. a belt main body having a flat belt-shaped back rubber portion and a plurality of tooth rubber portions provided on one side surface of the back rubber portion and formed of a rubber composition containing H-NBR as a main component;
a core wire embedded in the back rubber portion;
a tooth reinforcement cloth covering the surface on which the plurality of tooth rubber portions are provided;
has
The tooth portion reinforcing cloth uses aramid fiber as warp (thread extending in the belt width direction), polyurethane fiber as core thread, and aramid fiber and woolly nylon fiber as covering thread and composite yarn as weft (belt circumferential direction A toothed belt characterized in that it is a thread extending to the
2. The tooth reinforcing fabric has a warp direction tensile strength of 450 N/3 cm or more, a weft direction tensile strength of 150% or more of the warp direction tensile strength, and an elongation rate in the weft direction of the warp direction. 1. Characterized by an elongation rate of 500% or more. Toothed belt according to .
3. 1. The core wire is carbon fiber. or 2. Toothed belt according to .

In the toothed belt of the present invention, the tooth rubber portion is excellent in durability, and tooth chipping is less likely to occur when skipping occurs. Therefore, the skipped belt may be used continuously without being replaced immediately, and the replacement frequency can be reduced. The toothed belt of the present invention can be suitably used for high-load applications such as injection molding machines and machine tools where skips are likely to occur.
The toothed belt of the present invention can achieve high positional accuracy while being operated under a high load (high torque). Since the toothed belt of the present invention can be narrowed compared to conventional toothed belts and can be driven by a pulley with a small diameter, the entire device incorporating the toothed belt of the present invention can be made compact and energy-saving. can be realized.

1 is a perspective view of a toothed belt that is an embodiment of the present invention; FIG. FIG. 4 is a diagram for explaining a method of manufacturing a toothed belt that is an embodiment of the present invention; FIG. 4 is a diagram for explaining a method of manufacturing a toothed belt that is an embodiment of the present invention; FIG. 4 is a diagram for explaining a method of manufacturing a toothed belt that is an embodiment of the present invention; FIG. 4 is a diagram for explaining a method of manufacturing a toothed belt that is an embodiment of the present invention;

10 toothed belt 11 belt main body 11a back rubber portion 11b tooth rubber portion 12 core wire 13 tooth portion reinforcing cloth 14 tooth portion

20 belt mold 21 belt tooth forming groove 22 release paper 23 rubber sleeve

11' uncrosslinked rubber sheet S' uncrosslinked slab S belt slab

"toothed belt"
The toothed belt of the present invention is
a belt main body having a flat belt-shaped back rubber portion and a plurality of tooth rubber portions provided on one side surface of the back rubber portion and formed of a rubber composition containing H-NBR as a main component; It has a core wire embedded in the back rubber portion and a tooth reinforcement cloth that covers the surface of the side where a plurality of tooth rubber portions are provided. A weft yarn (a yarn extending in the circumferential direction of the belt) is composed of a core yarn made of polyurethane fiber and a covering yarn made of aramid fiber and woolly nylon fiber.

FIG. 1 shows a toothed belt 10 which is one embodiment of the present invention.
In the toothed belt 10, a core wire 12 is embedded in a belt body 11 as a tensile member so as to form a spiral with a constant pitch in the width direction of the belt. It is partitioned into the part 11b. Further, the toothed belt 10 has a tooth reinforcing cloth 13 at least partially embedded in the surface on which the tooth rubber portion 11b is provided, and the tooth reinforcing cloth 13 is located near the surface of the tooth rubber portion 11b. A tooth portion 14 is formed by embedding.

The toothed belt 10 is suitably used, for example, as a belt transmission device in an injection molding machine, a machine tool, etc., particularly as a power transmission member of the belt transmission device. The shape of the toothed belt 10 can be adjusted according to its use, but for example, the belt length is 70-6000 mm, the belt width is 6-200 mm, and the belt thickness is 1-20 mm. Further, the tooth rubber portion 11b has a width of 0.63 to 16.46 mm, a height of 0.37 to 9.6 mm, and a pitch of 1.0 to 31.75 mm, for example.
In this specification, the description of A to B (A and B are numerical values) means a numerical range including A and B, that is, from A to B and below.

The tooth rubber portion 11b may be a trapezoidal tooth having a trapezoidal shape in a side view, a semicircular round tooth, or any other shape. The tooth rubber portion 11b may be formed to extend in the belt width direction, or may be helical teeth formed to extend in a direction inclined with respect to the belt width direction.

·Rubber component The rubber composition forming the toothed belt 10 is mainly composed of H-NBR (hydrogenated acrylonitrile rubber). H-NBR may be reinforced with unsaturated carboxylic acid metal salts. In this specification, the term "main component" means that it contains 50% by weight or more of the whole.

H-NBR is obtained by hydrogenating unsaturated bonds in NBR, which is a copolymer of acrylonitrile and 1,3-butadiene, to make saturated bonds. In the H-NBR used in the present invention, the composition ratio of acrylonitrile and 1,3-butadiene can be appropriately adjusted according to workability and required physical properties. For example, from the viewpoint of oil resistance, the acrylonitrile content is preferably 20% by mass or more and 50% by mass or less, more preferably 30% by mass or more and 40% by mass or less. Moreover, the hydrogenation rate is preferably 80% or more, more preferably 90% or more. H-NBR may be used singly or in combination of two or more.
When reinforcing H-NBR, the unsaturated carboxylic acid of the unsaturated carboxylic acid metal salt includes, for example, methacrylic acid, acrylic acid, and the like, and the metal includes, for example, zinc, calcium, magnesium, aluminum, and the like. is mentioned.

The rubber composition used in the present invention may contain H-NBR as a main component, such as ethylene-propylene copolymer (EPR), ethylene-propylene-diene terpolymer (EPDM), ethylene-octene copolymer, ethylene-butene copolymer, and the like. ethylene-α-olefin elastomer, chloroprene rubber (CR), and chlorosulfonated polyethylene rubber (CSM).

The rubber composition used in the present invention may contain compounding agents as shown below.
Cross-linking agent As a cross-linking agent for cross-linking the rubber component, organic peroxides, sulfur, and these can be used in combination. Further, the rubber component may be crosslinked by using an electron beam or the like. Among these, from the viewpoint of wear resistance, it is preferable to use an organic peroxide. Specifically, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, α, α '-bis(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyldi(t-butyl)hexyne, 2, 5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxyisopropyl carbonate, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane and the like. One or more of these organic peroxides can be used in combination. The amount of the cross-linking agent compounded is, for example, about 1% by mass or more and 8% by mass or less with respect to 100% by mass of the rubber component.
Co-crosslinking agent Examples of the co-crosslinking agent include liquid rubber such as liquid NBR. The co-crosslinking agent can be used singly or in combination of two or more. The blending amount of the co-crosslinking agent is, for example, 3% by mass or more and 7% by mass or less with respect to 100% by mass of the rubber component.

Crosslinking aid Crosslinking aids include, for example, tetrahydrofurfuryl methacrylate, ethylene dimethacrylate, 1,3-butylene dimethacrylate, 1,4-butylene dimethacrylate, 1,6-hexanediol dimethacrylate, and polyethylene glycol dimethacrylate. , 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 2,2′-bis(4-methacryloxydiethoxyphenyl)propane, 2,2′-bis(4-acryloxydiethoxyphenyl ) Propane, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, 3-chloro-2-hydroxypropyl methacrylate, oligoester acrylate, aluminum methacrylate, zinc methacrylate, magnesium dimethacrylate, calcium dimethacrylate, triallyl isocyanurate, triallyl cyanurate, triallyl trimellitate, diallyl phthalate, diallylchlorendate, divinylbenzene, 2-vinylpyridine, N,N'-methylenebisacrylamide, p-quinonedioxin, p,p'-di benzoylquinine dioxin, 1,2-polybutadiene, dipentamethylenethiuram tetrasulfide and the like. The cross-linking aid can be used alone or in combination of two or more of these. The amount of the cross-linking aid added is approximately 0.1% by mass or more and 3.0% by mass or less with respect to 100% by mass of the rubber component.

Inorganic particles The rubber composition contains one or more inorganic particles such as silica, carbon black, titanium oxide, aluminum oxide, calcium carbonate, magnesium carbonate, zinc carbonate, barium sulfate, diatomaceous earth, clay, talc, and zinc oxide. can include The amount of the inorganic particles to be blended is preferably 10% by mass or more, more preferably 20% by mass or more, relative to 100% by mass of the rubber component. Moreover, the upper limit of this compounding amount is preferably 100% by mass or less, and more preferably 90% by mass or less. As the inorganic particles, it is preferable to use carbon black from the viewpoints of imparting conductivity, reinforcing properties, and preventing ultraviolet deterioration. Carbon black to be blended is not particularly limited, for example, channel black; furnace black such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, N-234; FT, MT thermal black such as;

The rubber composition of the present invention also contains processing aids, vulcanization accelerators, vulcanization accelerator aids, antioxidants, plasticizers, scorch inhibitors, UV absorbers, light stabilizers, softeners, foaming agents, Foaming aids, lubricants, flame retardants, antistatic agents, colorants, and the like may be included.
Processing aids include, for example, stearic acid, polyethylene wax, metal salts of fatty acids, and the like. 1 type(s) or 2 or more types can be used for a processing aid among these. The content of the processing aid is, for example, 0.5% by mass or more and 2% by mass or less with respect to 100% by mass of the rubber component.
Examples of vulcanization accelerators include thiuram-based (e.g., TETD, TT, TRA, etc.), thiazole-based (e.g., MBT, MBTS, etc.), sulfenamide-based (e.g., CZ, etc.), dithiocarbamate-based (e.g., BZ-P etc.) and the like. One or more of these vulcanization accelerators can be used. The content of the vulcanization accelerator is, for example, 2% by mass or more and 5% by mass or less with respect to 100% by mass of the rubber component.

Examples of vulcanization acceleration aids include metal oxides such as zinc oxide (zinc white) and magnesium oxide, metal carbonates, fatty acids and derivatives thereof. One or two or more of these can be used as vulcanization accelerators. The content of the vulcanization accelerator aid is, for example, 3% by mass or more and 7% by mass or less with respect to 100% by mass of the rubber component.
Anti-aging agents include, for example, amine-ketone-based anti-aging agents, diamine-based anti-aging agents, and phenol-based anti-aging agents. Anti-aging agent can use 1 type(s) or 2 or more types among these. The content of the antioxidant is, for example, 0.1% by mass or more and 5% by mass or less with respect to 100% by mass of the rubber component.
Examples of plasticizers include dialkyl phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), dialkyl adipates such as dioctyl adipate (DOA), and dialkyl sebacates such as dioctyl sebacate (DOS). The plasticizer is preferably one or more of these. The content of the plasticizer is, for example, 0.1% by mass or more and 40% by mass or less with respect to 100% by mass of the rubber component.
The rubber composition used in the present invention can also contain short fibers having a fiber diameter of 10 μm or more.

Core wire The core wire 12 used in the present invention is not particularly limited, and fiber materials such as glass fiber, aramid fiber, polyamide fiber, polyester fiber, metal fiber, and carbon fiber can be used. Among these, carbon fiber is preferable from the viewpoint of tensile strength, durability, and the like. As the carbon fiber, polyacrylonitrile (PAN)-based, petroleum/coal pitch-based, rayon-based, lignin-based, etc. can be used without particular limitation, but PAN-based is preferred. The diameter and pitch of the core wires 12 (the distance between the centers of mutually adjacent core wires in the cross section) can be adjusted according to the desired physical properties. It is about 0.1 to 5.0 mm. The core wire 13 can be subjected to an adhesive treatment for imparting adhesiveness to the toothed belt body 10 . The method of adhesion treatment is not particularly limited, but examples thereof include a method of immersing in rubber paste and then heat-treating, a method of immersing in RFL solution (resorcin-formalin-latex aqueous solution) and heat-treating, and the like.

Tooth reinforcement cloth In the present invention, the tooth reinforcement cloth 13 uses aramid fibers as warp yarns (threads extending in the belt width direction), polyurethane fibers as core yarns, and aramid fibers and woolly nylon fibers as covering yarns. The composite yarn is used as a weft yarn (a yarn extending in the circumferential direction of the belt). The tooth reinforcing cloth used in the present invention, or either or both of the warp and weft constituting the tooth reinforcing cloth may be subjected to the above-described bonding treatment.

As the warp, both para-aramid fibers and meta-aramid fibers can be used, but meta-aramid fibers are preferably used from the viewpoint of abrasion resistance.
The weft yarn is a composite yarn in which a polyurethane fiber with elongation is used as a core yarn, and this core yarn is covered with an aramid fiber with excellent strength and abrasion resistance, and a woolly nylon fiber with excellent elongation and shock absorption. .
The tooth reinforcing fabric is preferably plain weave or twill weave.

The tooth reinforcing cloth 13 used in the present invention is excellent in abrasion resistance and impact resistance by using the above specific fibers for the warp and weft. In the toothed belt of the present invention, the tooth reinforcing fabric 13 can be deformed (elongated) along the unevenness of the mold for forming the belt teeth when the toothed belt is manufactured. The surface can be coated to take full advantage of its abrasion resistance and impact resistance. The toothed belt of the present invention is excellent in durability against tooth chipping because the surface of the tooth rubber portion is covered with the tooth reinforcing cloth.
The tooth reinforcing cloth 13 has a tensile strength in the warp direction of 450 N/3 cm or more, and a tensile strength in the weft direction of 150% or more of the tensile strength in the warp direction. Moreover, it is preferable that the elongation rate in the weft direction is 500% or more of the elongation rate in the warp direction. Since the tooth reinforcing cloth 13 satisfies the above tensile strength and elongation, the tooth reinforcing cloth is excellent in strength and coverage.

- Manufacturing method The toothed belt of the present invention can be manufactured by a known method.
An example of the manufacturing method will be described below with reference to FIGS.
"Material preparation process"
After masticating a rubber component and kneading various rubber compounding agents therein to obtain an uncrosslinked rubber composition, it is formed into a sheet by calendar molding or the like to form an uncrosslinked rubber sheet 11'. prepare.
In addition, the core wire 12 and the tooth portion reinforcing cloth 13 which are subjected to adhesion treatment or the like are prepared as necessary.

"Molding process"
FIG. 2 shows a partial cross-sectional view of a belt mold 20 used for manufacturing the toothed belt 10. As shown in FIG. The belt forming die 20 is cylindrical, and belt tooth forming grooves 21 extending in the axial direction are formed on the outer peripheral surface thereof at regular intervals in the circumferential direction.
In the molding process, as shown in FIG. 3, the outer periphery of a belt molding die 20 is covered with a cylindrical tooth reinforcing cloth 13, the core wire 12 is spirally wound thereon, and the uncrosslinked rubber sheet 11 is further wound thereon. ' wrap around. At this time, an uncrosslinked slab S′ is formed on the belt mold 20 .

"Cross-linking process"
After wrapping the release paper 22 around the outer periphery of the uncrosslinked slab S', the rubber sleeve 23 is put thereon (Fig. 4).
This is placed in a vulcanization can and hermetically sealed, and the vulcanization can is filled with high-temperature, high-pressure steam and held in that state for a predetermined period of time. The temperature in the vulcanization vessel is, for example, 100° C. or higher and 200° C. or lower, and the pressure is, for example, 1.5 MPa or lower. The processing time is, for example, 5 minutes or more and 30 minutes or less.
As a result, the non-crosslinked rubber sheet 11' flows into the belt tooth forming grooves 21 and the crosslinking reaction progresses. At this time, the tooth portion reinforcing cloth 13 is pressed against the outer peripheral surface of the belt molding die 20 by being pressed by the rubber composition, thereby covering the surfaces of the belt tooth portions. Then, a cylindrical belt slab S in which the core wire 12 and the tooth reinforcing fabric 13 are combined and integrated with rubber is molded (FIG. 5).

"Finishing process"
The interior of the vulcanization can is depressurized to break the sealing, and the belt slab S molded between the belt molding die 20 and the rubber sleeve 23 is taken out and removed from the mold. After adjusting the width, the toothed belt 10 can be manufactured by cutting into rings of a predetermined width.
The manufacturing method described above is merely an example, and for example, the outer peripheral surface of the toothed belt 10 may be covered with another reinforcing cloth.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.
"Example 1"
A rubber component consisting of 45 parts by mass of H-NBR rubber (Nippon Zeon Zeptol 2000) and 55 parts by mass of NBR rubber (Nippon Zeon Zeoforte ZSC2195CX), 10 parts by mass of zinc oxide, anti-aging agent (2,2,4-trimethyl-1, 2-dihydroquinoline polymer) 10 parts by mass, antioxidant (2-mercaptobenzimidazole) 1 part by mass, antioxidant (4,4'-bis(α,α-dimethylbenzyl)diphenylamine) 1 part by mass, stearin Acid 0.5 parts by mass, carbon black (Showa Cabot, Show Black IP200) 20 parts by mass, polyether ester plasticizer (ADEKA ADEKA CIZER RS700) 10 parts by mass, cross-linking agent (NOF Peroximone F-40) 8 parts by mass , 0.5 parts by mass of a cross-linking agent (Hosoi Kagaku Kogyo oil-treated sulfur) and 3 parts by mass of a co-cross-linking agent (Seiko Kagaku High Cross M) are kneaded in a closed kneader to obtain an uncrosslinked rubber composition. was formed into a sheet by calendering to obtain an uncrosslinked rubber sheet.

Cord: PAN-based carbon fiber (diameter: 1.1 mm, with adhesion treatment by immersion) was used.
Reinforcing fabric for teeth: Meta-aramid (No. 30/2) for warp, polyurethane (470 dtex/1) for weft, and covering yarn for para-aramid (220 dtex/1) and woolly nylon (78 dtex/2) It is a composite yarn that is a composite yarn, and is a tooth reinforcement cloth (warp 90 ± 10 / 5 cm, weft 90 ± 10 / 5 cm) that has been subjected to adhesion treatment with RFL liquid (resorcin / formalin / latex aqueous solution) and H-NBR adhesive. was used.

An S8M type toothed belt with a circumference length of 1000 mm, a width of 10 mm, and a pitch of the cords of 3 mm was obtained using the uncrosslinked rubber sheet, cords, and tooth reinforcement fabric according to the above-described manufacturing method.

"Comparative Example 1"
Reinforcing fabric for teeth (warp 175±20/5cm, weft 172±15/ A toothed belt was obtained in the same manner as in Example 1, except that 5 cm) was used.

"Comparative Example 2"
The warp is nylon (235 dtex/1), and the weft is woolly nylon (155 dtex/2). A toothed belt was obtained in the same manner as in Example 1, except that 190±14 threads/5 cm and 140±10 threads/5 cm of wefts were used.

"Comparative Example 3"
The warp is nylon (235 dtex/1), and the weft is woolly nylon (235 dtex/3). A toothed belt was obtained in the same manner as in Example 1 except that 120±8 wefts/5 cm and 120±7 wefts/5 cm of wefts were used.

The tooth reinforcing cloth was evaluated as follows. Table 1 shows the results.
・Tensile strength, elongation The cutting strength and elongation when the tooth reinforcing cloth is pulled at a speed of 200 mm / min are measured using a static tensile compression tester (manufactured by Shimadzu Corporation, device name: AUTOGRAPH AG-5000A). ) was used. Elongation was measured with a ruler. In addition, the measurement is performed 10 times and the arithmetic mean value is shown

The toothed belts thus obtained were evaluated as follows. Table 1 shows the results.
- Rubber hardness The rubber hardness of the back surface of the toothed belt was measured using a type A durometer according to JIS K6253-3:2012. Measurements were taken on the dorsal surface of the toothed portion.
Breaking strength Breaking strength when the belt was pulled at a speed of 50 mm/min was measured using a static tensile compression tester (manufactured by Shimadzu Corporation, device name: AUTOGRAPH AG-5000A). In addition, the measurement is performed on 10 belts, and the arithmetic mean value is shown.
·Skip (tooth skipping) durability test The obtained toothed belt was put on two pulley shafts, and the driving side pulley was rotated while the driven side pulley was fixed to cause the belt to skip. The toothed belt was removed every 10th, 20th, 50th and 100th skips, and the weight of the belt was measured to determine the weight reduction rate.
Test conditions Drive pulley: 32 teeth, 1 rpm
Driven pulley: 48 teeth (fixed)
Span tension: 23 N (contact pressure 88 N/mm ² )

·Tooth Chipping Durability Test The belt was skipped in the same manner as in the above tooth chipping durability test 1, except that the inter-span tension was set to 150 N (surface pressure: 118 N/mm ² ). The value of the torque meter installed on the drive side is recorded using a multi-input data logger (Keyence NR-500), the occurrence of skipping and tooth chipping is determined from changes in torque, and when tooth chipping occurs. We asked for the number of skips. In addition, the measurement is performed on 10 belts, and the arithmetic mean value is shown.

Compared to the toothed belt obtained in Comparative Example 1, the toothed belt obtained in Example 1 of the present invention has a weight reduction of less than half when skipping occurs, and the rubber is less likely to be chipped. The number of skips until chipping occurred was large, and the durability of the tooth rubber portion was excellent.
The toothed belt obtained in Example 1, which is the present invention, has a large number of skips until tooth chipping occurs, which is about 10 times (≈173/18.6) that of the toothed belt obtained in Comparative Example 1. Since it is not necessary to replace immediately even if a skip occurs, the replacement frequency can be reduced.

Claims

a belt main body having a flat belt-shaped back rubber portion and a plurality of tooth rubber portions provided on one side surface of the back rubber portion and formed of a rubber composition containing H-NBR as a main component;
a core wire embedded in the back rubber portion;
a tooth reinforcement cloth covering the surface on which the plurality of tooth rubber portions are provided;
has
The tooth portion reinforcing cloth uses aramid fiber as warp (thread extending in the belt width direction), polyurethane fiber as core thread, and aramid fiber and woolly nylon fiber as covering thread and composite yarn as weft (belt circumferential direction A toothed belt characterized in that it is a thread extending to the
The tooth reinforcing fabric has a warp direction tensile strength of 450 N/3 cm or more, a weft direction tensile strength of 150% or more of the warp direction tensile strength, and an elongation rate in the weft direction of the warp direction. 2. The toothed belt according to claim 1, wherein the elongation rate is 500% or more.
The toothed belt according to claim 1 or 2, wherein the core wire is carbon fiber.