JP2022171370A - Synchronous belt - Google Patents

Abstract

To provide a toothed belt 10 that has excellent flexural fatigue resistance 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 tooth rubber part 11b both of which are composed of a thermoplastic elastomer composition, a core wire 13 buried in the back rubber part 11a, and a tooth part covering material 14 that covers the tooth rubber part 11b. The thermoplastic elastomer composition comprises an elastomer component that is a polyamide thermoplastic elastomer or a polyester thermoplastic elastomer. The back rubber part 11a has hardness of 25-70. The tooth rubber part 11b has hardness of 40-70, which is equal to or greater than the hardness of the back rubber part 11a. The core wire 13 has yarn 16 having two or more twist layers. The yarn 16 includes two or more strands 17. Each strand 17 comprises multiple twisted filaments 18 containing a carbon filament composed of a carbon fiber.SELECTED DRAWING: Figure 1

Description

The present invention relates to toothed belts.

Conventionally, rubber belts and cast urethane belts are known as toothed belts. Each of these belts has a back rubber portion, a large number of tooth rubber portions integrally provided on the back rubber portion at a predetermined pitch in the longitudinal direction of the belt, and a belt between the back rubber portion and the tooth rubber portion. core wires extending in the longitudinal direction and embedded at a predetermined pitch in the width direction of the belt. Both are different in that the back rubber portion and tooth rubber portion are molded from vulcanized rubber or cast urethane.

These belts require a vulcanization process and a post-vulcanization process in the manufacturing process, and therefore have low productivity. Further, these belts have the problem that post-processing such as shaping after belt molding is difficult due to the properties of vulcanized rubber and cast urethane, and recycling is also difficult.

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

JP-A-7-27178 JP-A-10-2379

A toothed belt in which a thermoplastic elastomer is used to form the back rubber portion and the tooth rubber portion has a problem that the teeth of the belt tend to deform when the load applied to the belt increases. Furthermore, when the rotation speed of the pulley on which the belt is hung increases, the belt generates heat, and in this case also, there is a problem that the teeth of the belt are easily deformed.

Carbon fibers are less likely to be deformed by creep than organic fibers. Therefore, by adopting a yarn made of carbon fiber as the core wire, the toothed belt can suppress a decrease in tension due to use. This toothed belt has the prospect of long-term use.
In the above-mentioned Patent Document 2, a single-twisted yarn obtained by single-twisting a filament made of carbon fiber (hereinafter referred to as carbon filament) is employed as the core wire.
When the twist of the yarn is strengthened, the strength of the yarn increases, but the carbon filaments in the surface layer are strained more than the carbon filaments in the center.
Carbon filaments are rigid and have a small elongation at break. Therefore, in the single-twisted yarn described above, if the twist is increased in order to increase the strength of the yarn, there is a concern that the carbon filaments in the surface layer may be cut. Cutting the carbon filaments reduces the strength of the yarn.
The pulley bends the toothed belt. This causes strain in the core wire. The smaller the pulley diameter, the greater the strain that occurs in the core wire. Since the occurrence and disappearance of strain are repeated in the core wire, there is a concern that the core wire may break due to bending fatigue when the single-twisted yarn described above is used as the core wire.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toothed belt that is excellent in bending fatigue resistance and suitable for high-load transmission.

(1) The toothed belt of the present invention comprises a flat belt-shaped back rubber portion and a plurality of belt teeth disposed on the inner peripheral side of the back rubber portion and integrally provided with the back rubber portion to form belt teeth. and a belt body in which both the back rubber portion and the tooth rubber portion are made of a thermoplastic elastomer composition; and a tooth portion covering material covering the plurality of tooth rubber portions provided on the inner peripheral side of the belt body, wherein the thermoplastic elastomer composition The elastomer component is a polyamide-based thermoplastic elastomer (TPAE) or a polyester-based thermoplastic elastomer (TPC), the thermoplastic elastomer composition constituting the back rubber portion has a hardness of 25 to 70, and the tooth The thermoplastic elastomer composition constituting the rubber portion has a hardness of 40 to 70 and is equal to or higher than the hardness of the thermoplastic elastomer composition constituting the back rubber portion, and the core wire has two or more twist layers. wherein the yarn comprises two or more strands, each strand comprising a number of twisted filaments including carbon filaments made of carbon fibers.

In the toothed belt, the back rubber portion and the tooth rubber portion are made of a composition containing thermoplastic polyamide elastomer (TPAE) or thermoplastic polyester elastomer (TPC) as an elastomer component. Therefore, no vulcanization step or post-vulcanization step is required in the manufacturing process, and the toothed belt is excellent in productivity. In addition, the elastomer component is resistant to heat, and the elastic modulus does not decrease even when the belt is driven at a high load or at a high rotational speed. As a result, deformation is less likely to occur when the belt is driven, and problems such as tooth jumping caused by deformation of the tooth rubber portion are less likely to occur. This toothed belt is suitable for high load transmission.

Further, in the toothed belt, the thermoplastic elastomer composition constituting the back rubber portion and the tooth rubber portion each has a specific hardness. For this reason, the belt is too soft and deforms when it receives power, resulting in chipping of teeth, while the belt is too hard and is damaged when wound around pulleys, and cracks occur on the back of the belt during driving. can be suppressed.
In the above toothed belt, the yarns forming the cords contain carbon filaments. Since the elastic modulus of the carbon filaments is high, even if a high load is applied to the toothed belt, deformation is unlikely to occur, and engagement with the pulleys is unlikely to shift. As a result, it is possible to prevent the belt from running over the pulley due to misengagement between the belt and the pulley, and the loss of belt teeth due to localized force applied to the belt. In addition, since carbon filaments do not have the creep property of filaments made of organic fibers, the toothed belt is very difficult to stretch and the tension of the toothed belt is less likely to decrease.
Furthermore, the yarn has two or more twist levels. The same twist strength induces less strain in the filaments than filaments in yarns composed of a single layer of ply. Since the compressive strain on the surface of the yarn is kept small, the filaments are less likely to break even when the yarn is bent. Since the carbon filament is difficult to cut, the core wire is prevented from being cut due to bending fatigue.
With this toothed belt, a state suitable for high-load transmission is maintained over a long period of time.

(2) In the toothed belt, the elastomer component of the thermoplastic elastomer composition is preferably thermoplastic polyamide elastomer (TPAE). TPAE is suitable as a material for composing the tooth rubber portion and the back rubber portion of the toothed belt because of its small energy loss against dynamic deformation, little heat generation due to bending, and excellent chemical resistance.

(3) In the toothed belt, it is preferable that the yarn has two layers of twist consisting of a primary twist and a final twist, and is twisted in a ply twist. In this case, the cord can stably retain its shape without being entangled. Therefore, it is possible to prevent the core wire spacing from being disturbed in the production of the toothed belt. Friction with the flange due to meandering of the toothed belt is reduced.

(4) In the toothed belt, the yarn preferably has two layers of twist, consisting of a first twist and a first twist, and is twisted in a Lang twist. In this case, since friction between the carbon filaments is reduced, deterioration in strength of the core wire due to abrasion is prevented. Since the filaments in the yarn surface layer are greatly inclined with respect to the longitudinal direction of the belt, the carbon filaments are less likely to break even in applications such as small pulleys in which the toothed belt is subject to a large compressive strain.

(5) In the toothed belt, the yarn has three twist layers consisting of a primary twist, a middle twist, and a final twist, and the direction of the primary twist and the direction of the middle twist are the same. more preferred. In this case, twisting causes less strain in the filaments than in filaments contained in a yarn having two layers of twist. Since the carbon filament is difficult to cut, the core wire is prevented from being cut due to bending fatigue.

(6) In the toothed belt, the yarn preferably has a total twist factor of more than 30 and not more than 120 in each twist layer. In this case, this toothed belt can increase the strength of the yarn while reducing the distortion caused in the filaments by twisting. Since the carbon filament is difficult to cut, the core wire is prevented from being cut due to bending fatigue.

(7) In the toothed belt, the yarn preferably has a twist coefficient of 100 or less in the ply twist. In this case, breakage of the carbon filaments due to excessive twisting in the ply twist is prevented. Therefore, the cord is less likely to break due to bending fatigue.

(8) In the toothed belt, it is more preferable that the yarn has a twist coefficient of ply twist of 30 or more and 60 or less. In this case, the cord has an appropriate strength, and the distortion of the carbon filaments caused by twisting is moderately suppressed. Therefore, cutting of the cord due to bending fatigue is effectively prevented.

(9) In the toothed belt, the strands preferably contain polyamide filaments made of polyamide fibers. In this case, the polyamide filaments act as binders between the carbon filaments. Since the friction of the carbon filaments is suppressed, this toothed belt prevents the reduction in the strength of the cord due to the wear of the carbon filaments.

(10) In the toothed belt, the ratio of the volume of the polyamide filaments to the sum of the volume of the carbon filaments and the volume of the polyamide filaments in the strand is preferably 3 to 12% by volume. In this case, the polyamide filaments effectively function as binders between the carbon filaments. Since the friction of the carbon filaments is suppressed, this toothed belt prevents the reduction in the strength of the cord due to the wear of the carbon filaments.

(11) In the toothed belt, each filament in the strand is coated with a converging coating layer made of a sizing agent, the sizing agent contains an epoxy group-containing compound and a curing agent, and has a solid content of 80% by mass. It is preferable that it is above. In this case, since the converging coating layer exists between the filaments, the filaments are prevented from being directly rubbed against each other, and the movement of the filaments is suppressed. Since the friction of the carbon filaments is suppressed, this toothed belt prevents the reduction in the strength of the cord due to the wear of the carbon filaments.

(12) In the toothed belt, the curing agent is preferably an isocyanate curing agent or an amine curing agent. In this case, rubbing of the carbon filament is suppressed. Therefore, the reduction in strength of the core wire due to wear of the carbon filaments is prevented.

(13) In the toothed belt, each filament in the strand is coated with a converging coating layer made of a sizing agent, the sizing agent containing resorcinol and formaldehyde and having a solid content of 80% by mass or more. can also In this case also, since the converging coating layer exists between the filaments, the filaments are prevented from being directly rubbed against each other, and the movement of the filaments is suppressed. Since the friction of the carbon filaments is suppressed, this toothed belt prevents the reduction in the strength of the cord due to the wear of the carbon filaments.
Compared to the case where a solution containing an epoxy group-containing compound and a curing agent is used as a sizing agent, a softer converging coating layer is formed, so that although the filaments are constrained by this converging coating layer, they can move slightly. . Since the filaments are easy to bend, this toothed belt facilitates yarn bonding. In this toothed belt, the yarn is strongly adhered to the belt body. Therefore, even if a high load acts on this toothed belt, the yarn is less likely to separate from the belt body. A soft converging coating layer effectively relieves the strain induced in the yarn. Therefore, even if this toothed belt is used for a pulley with a small pulley diameter, the cord is less likely to be cut.

(14) In the toothed belt, the yarn is coated with an adhesive coating layer made of an adhesive, the adhesive contains an epoxy group-containing compound and a curing agent, and has a solid content of 80% by mass or more. Preferably. In this case, not only the movements of the filaments contained in the strands but also the movements of the strands contained in the yarn are restrained. Therefore, the friction of the carbon filaments is suppressed. This toothed belt effectively prevents a reduction in the strength of the cord due to wear of the carbon filaments.

(15) In the toothed belt, the curing agent for the adhesive is preferably an isocyanate curing agent or an amine curing agent. In this case, rubbing of the carbon filament is suppressed. Therefore, the reduction in strength of the core wire due to wear of the carbon filaments is prevented.

ADVANTAGE OF THE INVENTION According to this invention, the toothed belt which is excellent in bending fatigue resistance and suitable for high-load transmission is obtained.

It is a perspective view showing typically a part of toothed belt concerning one embodiment of the present invention. It is a front view of arrow X in FIG. FIG. 2 is an end view taken along line AA of FIG. 1; FIG. 2 is a cross-sectional view showing an example of yarn; FIG. 4 is a cross-sectional view showing a modified example of yarn; FIG. 4 is a partial cross-sectional view of a belt mold used for manufacturing toothed belts; It is a figure explaining the manufacturing process of a toothed belt. It is a figure explaining the manufacturing process of a toothed belt. It is a figure explaining the manufacturing process of a toothed belt. It is a figure which shows the pulley layout in the 1st running test. It is a figure which shows the pulley layout in a 2nd running test. It is a figure which shows the pulley layout in a 3rd running test.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The invention is not limited to these embodiments.
FIG. 1 is a perspective view showing part of a toothed belt 10 according to an embodiment of the invention. 2 is a front view of arrow X in FIG. 1. FIG. FIG. 3 is an end view taken along line AA of FIG. 1. FIG.

<Toothed belt>
The toothed belt 10 is an endless meshing transmission belt.
Only a portion of the toothed belt 10 is shown in FIG.
The toothed belt 10, as shown in FIG. 1, includes a belt body 11, cords 13, and a reinforcing cloth 14 as a tooth covering material.

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 are, for example, a belt circumference (belt length on 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 belt maximum thickness of 1.3 mm or more and 13.2 mm or less. can be

A plurality of belt teeth 12 are arranged on the inner peripheral side of the toothed belt 10 at predetermined intervals. The tooth profile of the belt teeth 12 is an S tooth profile.
In the embodiment of the present invention, the tooth profile of the belt teeth 12 is not limited to the S tooth profile, and may be an arc tooth profile other than the S tooth profile, a trapezoidal tooth profile, or any other tooth profile. may

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

In the toothed belt 10, the tooth pitch P (see P in FIG. 3) of the belt teeth 12 is, for example, 2 mm or more and 20 mm or less.
The tooth height of the belt tooth 12 is defined by the dimension from the tooth bottom 15 between a pair of belt teeth 12 adjacent to each other in the belt length direction to the tip of the belt tooth 12 (see H in FIG. 3). It is 0.76 mm or more and 8.4 mm or less.
Further, the toothed belt 10 has, for example, the number of teeth of 27 or more and 560 or less, a tooth width (lengthwise dimension of the belt) of, for example, 1.3 mm or more and 15.0 mm or less, and a PLD of, for example, 0.254 mm or more. 159 mm or less.
These belt tooth dimensions are exemplary and not intended to be limiting in these ranges.

<belt body>
The belt body 11 has an endless flat belt-shaped back rubber portion 11a and a plurality of tooth rubber portions 11b. A plurality of tooth rubber portions 11 b are provided on the inner peripheral side of the belt body 11 . Specifically, the plurality of tooth rubber portions 11b are integrally provided on the inner peripheral side, which is one side of the back rubber portion 11a, at intervals in the lengthwise direction of the belt. In the belt body 11, each of the back rubber portion 11a and the tooth rubber portion 11b is made of a thermoplastic elastomer composition.
The thermoplastic elastomer composition forming the back rubber portion 11a and the thermoplastic elastomer composition forming the tooth rubber portion 11b may be the same or different.

In the present invention, the thermoplastic elastomer composition refers to a composition containing a thermoplastic elastomer component as an essential component and optionally containing various additives other than the elastomer component.
The thermoplastic elastomer composition may contain only the elastomer component.

The elastomer component of the thermoplastic elastomer composition forming the belt body 11 is thermoplastic polyamide elastomer (TPAE) or thermoplastic polyester elastomer (TPC).
TPAE and TPC are more resistant to heat than other thermoplastic elastomers such as olefinic, styrene, and urethane elastomers, and their elastic modulus is less likely to decrease even at belt temperatures during high-load driving or high-speed rotational driving. Therefore, deformation of the tooth rubber portion 11b due to heat generated by the belt is less likely to occur during high-load driving or high-speed rotational driving.

As the elastomer component, a polyamide-based thermoplastic elastomer (TPAE) is preferable.
TPAE has less energy loss in dynamic deformation and less heat generation due to bending than TPC. Therefore, the belt temperature during driving is relatively low, making it suitable for high-load and high-speed power transmission.
TPAE also has excellent chemical resistance. Therefore, it is suitable as a toothed belt for use in applications where contact with chemicals is expected, for example, industrial machinery equipped with a hydraulic system, drive units for two-wheeled vehicles, and electric seats for passenger cars.

The thermoplastic polyester 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.

The thermoplastic polyamide elastomer (TPAE) is a block copolymer having polyamide (nylon) as a hard segment and polyol as a soft segment.
Examples of the polyamide (nylon) 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 susceptible to dimensional change.

As the polyol, one or both of polyester polyol and polyether polyol can be employed.
When polyester polyol and polyether polyol are compared, it is easy to exhibit rubber elasticity at room temperature without blending a plasticizer, and cracks are less likely to occur when the belt is bent. is preferred. In this case, the soft segment has a polyether structure.
Further, when polyether polyol is used as the polyol component of TPAE, it is not necessary to blend a plasticizer, and the tooth rubber portion 11b and the back rubber portion 11a are made of a thermoplastic elastomer composition that does not contain a plasticizer. In the toothed belt 10 configured with , the plasticizer does not volatilize and adhere to equipment and products. Therefore, such toothed belt 10 can be suitably used in a clean room.

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

Commercially available products may be used as the thermoplastic polyester elastomer and the thermoplastic polyamide elastomer.
Examples of commercially available polyester thermoplastic elastomers include the Hytrel (registered trademark) series manufactured by DuPont-Toray.
Commercially available products of the thermoplastic polyamide elastomer include, for example, PEBAX (registered trademark) series manufactured by Arkema, VESTAMID (registered trademark) series and DAIAMID (registered trademark) series manufactured by Daicel-Evonik, and EMS Grillflex (registered trademark) series can be exemplified.

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

On the other hand, when these additives are contained, these additives may detach from the back rubber portion 11a and the tooth rubber portion 11b and contaminate the usage environment. Therefore, when the toothed belt 10 is, for example, a toothed belt used in a clean room, the thermoplastic elastomer composition preferably does not contain the above additives and is composed only of elastomer components.

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

The hardness of the thermoplastic elastomer composition is measured at 23° C. using a type D durometer according to JIS K6253-3. This hardness is also called Shore D hardness.

Hereinafter, in the present specification, the hardness of the thermoplastic elastomer composition forming the back rubber portion 11a is also referred to simply as the "back rubber portion hardness", and the hardness of the thermoplastic elastomer composition forming the tooth rubber portion 11b. The hardness is also simply referred to as "tooth rubber portion hardness".

In the toothed belt having such a structure, the hardness of the back rubber portion is within the above range and less than the hardness of the tooth rubber portion, so that it may be damaged when wound around a pulley, or cracks may occur on the back surface of the belt during driving. To be restrained from occurring or to occur. Further, since the hardness of the tooth rubber portion is equal to or higher than the hardness of the back rubber portion and is within the above range, the teeth of the belt are less likely to be worn during use, and deformation of the belt teeth is less likely to occur.
The hardness of the thermoplastic elastomer composition forming the back rubber portion 11a may be lower than the hardness of the thermoplastic elastomer composition forming the tooth rubber portion 11b.

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

In the toothed belt 10, it is also preferable that the hardness of the back rubber portion is 25-50 and the hardness of the tooth rubber portion is 45-65. In this case, it is suitable for simultaneously suppressing the generation of back surface cracks and suppressing the deformation of the belt teeth.

The hardness of the back rubber portion is determined by the molecular weight of the elastomer component contained in the thermoplastic elastomer composition that constitutes the back rubber portion 11a, the ratio of the hard segment to the soft segment, and the addition of components other than the elastomer component contained in the thermoplastic elastomer composition. It can be controlled by adjusting the type and amount of the agent.
Similarly, the hardness of the tooth rubber portion can be controlled by the elastomer component contained in the thermoplastic elastomer composition constituting the tooth rubber portion 11b and additives other than the elastomer component.

<Reinforcing cloth>
The reinforcing cloth 14 is attached so as to cover the surface of the belt body 11 on the inner peripheral side where the plurality of tooth rubber portions 11b are provided. Accordingly, the tooth rubber portion 11b of each belt tooth 12 is covered with the reinforcing cloth 14. As shown in FIG.
This prevents direct contact between the thermoplastic elastomer composition forming the tooth rubber portion 11b and the pulley. Therefore, wear of the tooth rubber portion 11b can be suppressed.
The thickness of the reinforcing cloth 14 is, for example, 0.1 mm or more and 2.5 mm or less.

The reinforcing cloth 14 is made of a fibrous member such as a woven cloth, a knitted cloth, a nonwoven cloth, a resin film, or the like.
Examples of yarns for forming the fiber member include nylon fibers (polyamide fibers), polyester fibers, aramid fibers, polyparaphenylenebenzobisoxazole (PBO) fibers, and cotton.
Examples of materials for the resin film include nylon (polyamide) and polyester.

Among these, a fibrous member formed mainly of nylon fibers and a nylon film (hereinafter, both are collectively referred to as a nylon reinforcing cloth) are preferable.
Since the nylon reinforcing cloth has a low coefficient of friction, the frictional energy is small and it is hard to wear.
In addition, since the nylon reinforcing cloth has a high melting point, even if the temperature of the contact portion with the pulley rises, the nylon reinforcing cloth is unlikely to be melted and rapidly worn.
The reinforcing cloth 14 may be, for example, a stretchable cloth such as a woven cloth whose wefts are woolly processed.
Here, having nylon fibers as a main component means that the amount of nylon fibers contained in all fibers is 50% by mass or more.

The reinforcing cloth 14 is subjected to an RFL treatment in which the reinforcement cloth 14 is immersed in an RFL aqueous solution and then heated as an adhesion treatment for enhancing adhesion to the belt body 11 .
Prior to the bonding treatment, the reinforcing cloth 14 may be subjected to a base treatment in which it is immersed in an epoxy solution or an isocyanate solution and then heated.

The reinforcing cloth 14 may contain wear modifiers such as PTFE (polytetrafluoroethylene) particles, ultra-high molecular weight polyethylene particles (for example, average molecular weight of 1,000,000 or more) on the surface or inside thereof.
When the reinforcing cloth 14 contains a wear modifier, deformation due to wear of the tooth rubber portion 11b is further suppressed.

The PTFE particles and the ultra-high-molecular-weight polyethylene particles may be dispersed in the above-mentioned RFL aqueous solution in advance, and may be included in the reinforcing cloth 14 by performing a treatment using the RFL aqueous solution.

When the reinforcing cloth 14 is made of a resin film, the PTFE particles or the ultra-high molecular weight polyethylene particles are dispersed in the resin film in advance, so that the reinforcing cloth 14 contains the PTFE particles or the like. good.

<Core wire>
The core wire 13 is embedded in the inner peripheral portion of the back rubber portion 11a of the belt body 11 so as to form a spiral having a pitch in the width direction of the belt.
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 cords 13 (arrangement pitch in the belt width direction) is, for example, 0.5 mm or more and 4.0 mm or less.
The core 13 of this toothed belt comprises a yarn 16 comprising two or more strands.

FIG. 4A is a cross-sectional view showing an example of yarn 16. FIG. This yarn 16a includes five strands 17a. Each strand 17a includes a number of filaments 18. FIG.
In producing the yarn 16, a large number of filaments 18 are twisted to form a strand 17a. Yarn 16a is formed by twisting five strands 17a. Twisting the filaments 18 together to form the strand 17a is the primary twist, and twisting the strands 17a together to form the yarn 16a is the ply twist. The yarn 16a shown in this FIG. 4 has two layers of twist consisting of a ply and a ply.

FIG. 4B is a cross-sectional view showing a modification of the yarn 16. FIG. This yarn 16b includes five strands 17b. Each strand 17b includes three temporary strands 19. FIG. Each temporary strand 19 contains a number of filaments 18 .
In producing the yarn 16b, a large number of filaments 18 are twisted to form a temporary strand 19. FIG. The three temporary strands 19 are twisted together to form the strand 17b. Yarn 16b is formed by twisting five strands 17b. Twisting the filaments 18 together to form the false strand 19 is the primary twist, twisting the false strands 19 together to form the strand 17b is the middle twist, and twisting the strand 17b together to form the yarn 16b. Twisting is ply twisting. The yarn 16 shown in this FIG. 5 has three layers of twist consisting of a base twist, a middle twist and a top twist.

Cord 13 comprises yarn 16 having two or more layers of twist. As noted above, yarn 16 includes two or more strands 17 , each strand 17 including multiple filaments 18 . In this toothed belt 10, all or part of the filaments 18 included in the strands 17 are carbon filaments made of carbon fibers. Strand 17 contains carbon filaments. The strand 17 is formed by twisting together a large number of filaments 18 including carbon filaments.
The filament diameter of the carbon filament is, for example, 5 μm or more and 7 μm or less. The number of carbon filaments included in the yarn 16 is, for example, 3000 or more. The upper limit of the number of filaments is not particularly limited, and is, for example, 96,000.

Carbon filaments include, for example, PAN-based carbon filaments and pitch-based carbon filaments. A PAN-based carbon filament is preferable as the carbon filament because of its flexibility.

As described above, the yarns 16 that make up the cord 13 include carbon filaments. Since the elastic modulus of the carbon filaments is high, even if a high load is applied to the toothed belt 10, deformation is unlikely to occur, and engagement with the pulleys is unlikely to shift. Therefore, it is possible to prevent the toothed belt 10 from riding on the pulley due to the meshing between the toothed belt 10 and the pulley being deviated, or the belt tooth 12 being chipped due to local force being applied to the toothed belt 10.例文帳に追加can be done. In addition, since the carbon filaments do not have the creep property of the filaments 18 made of organic fibers, the toothed belt 10 is very difficult to stretch and the tension of the toothed belt 10 does not easily decrease.
Furthermore, because yarn 16 has two or more layers of twist, the same amount of twist occurs in filament 18 compared to a yarn formed with a single layer of twist (also referred to as a single-ply yarn). Distortion is small. Since the compressive strain on the surface of the yarn 16 is kept small, the filament 18 is less likely to break even when the yarn 16 is bent. Since the carbon filaments are difficult to cut, the toothed belt 10 prevents the core wires 13 from being cut due to bending fatigue.

As mentioned above, the yarn 16b shown in FIG. 4A has two layers of twist consisting of a ply and a ply.
When the yarn 16 has two layers of twist, a plurality of strands 17 obtained by under-twisting a large number of filaments 18 in one direction (direction of S twist or direction of Z-twist) are gathered and twisted in the direction of the first twist. A strand 17 obtained by twisting a large number of filaments 18 in one direction (S-twisting direction or Z-twisting direction). The yarn 16 may be twisted by a so-called Lang twist, in which a plurality of yarns are collected and ply twisted in the same direction as the first twist.

When the yarn 16 is twisted in a ply, the core wire 13 can stably retain its shape without being entangled. Therefore, it is possible to prevent the spacing between the core wires 13 from being disturbed in the production of the toothed belt 10 . Friction with the flange due to meandering of the toothed belt 10 is reduced.
When the yarn 16 is lang-twisted, the friction between the carbon filaments is reduced, thereby preventing the reduction in strength of the core wire 13 due to abrasion. Since the filaments 18 in the surface layer of the yarn 16 are greatly inclined with respect to the longitudinal direction of the belt, the carbon filaments are less likely to break even in applications such as small pulleys in which the toothed belt 10 is subject to a large compressive strain.

As mentioned above, the yarn 16b shown in FIG. 4B has three layers of twist consisting of a base twist, a middle twist and a top twist.
If the yarn 16 has three layers of twist, the direction of the base twist and the direction of the middle twist are preferably the same. This results in less strain in the filaments 18 due to twisting than in the filaments 18 contained in the yarn 16a having two layers of twist. Since the carbon filament is difficult to cut, the core wire is prevented from being cut due to bending fatigue. In this case, the shape of the core wires 13 can be stably maintained without being entangled, and the spacing of the core wires 13 can be prevented from being disturbed in the production of the toothed belt 10. Therefore, the direction of the upper twist is the direction of the middle twist. and more preferably in the opposite direction.

As noted above, yarn 16 has two or more layers of twist. In this yarn 16, the sum of the twist moduli in each layer of twist (e.g., for yarn 16a shown in FIG. 4A, the sum of the twist modulus of the ply and the ply twist, the yarn 16b shown in FIG. 4B Then, the sum of the twist coefficient of the first twist, the twist coefficient of the middle twist, and the twist coefficient of the top twist) is preferably more than 30 and 120 or less.

By setting the total twist factor greater than 30, the strength of the yarn 16 is increased. The cord 13 including this yarn 16 has an appropriate strength and can effectively contribute to high load transmission.
By setting the total twist factor to 120 or less, the distortion caused in the filaments 18 by twisting is reduced. Carbon filament breakage due to excessive twisting is prevented. Therefore, the core wire 13 is less likely to break due to bending fatigue.

For yarn 16a shown in FIG. 4A and yarn 16b shown in FIG. 4B, ie, yarn 16 having two or more layers of twist, the ply twist preferably has a twist factor of 100 or less. In this case, breakage of the carbon filaments due to excessive twisting is prevented. Therefore, the core wire 13 is less likely to break due to bending fatigue. From this point of view, the twist coefficient of the ply twist is more preferably 60 or less. From the viewpoint that the core wire 13 has an appropriate strength and can effectively contribute to high-load transmission, the twist coefficient of the ply twist is preferably 30 or more.

In the yarn 16a shown in FIG. 4A, i.e., a yarn 16 having two layers of twist, the twist factor of the ply twist may be the same as the twist factor of the ply twist, and the twist factor of the ply twist is equal to that of the ply twist. It may be different from the twist factor.

In the yarn 16b shown in FIG. 4B, i.e., the yarn 16 having three layers of twist, the sum of the twist factor of the first twist and the twist factor of the middle twist (hereinafter, the total twist factor of the first twist and the middle twist) The twist factor of the twist may be the same, or the total twist factor of the first twist and the middle twist may be different from the twist factor of the top twist.

In the yarn 16 having three layers of twist, the ratio of the twist coefficient of the first twist to the total twist coefficient of the first twist and the middle twist is 5% or more from the viewpoint of effectively reducing the strain generated in the filament 18 by twisting. It is preferably 30% or less.

Regarding the above-mentioned twist coefficient, the twist coefficient is K, the number of twists per unit length is T (twists/m), and the fineness of the fiber bundle (temporary strand 19, strand 17 or yarn 16) to be twisted is D ( dtex), it is represented by the following equation (1).
K=T×√D/100 (1)
For example, when the yarn 16 has two layers of twist, the fineness of the strand 17 obtained by the first twist is used as the fineness D of the fiber bundle to be twisted in calculating the twist coefficient K of the first twist. In calculating the twist coefficient K of the ply twist, the fineness of the yarn 16 obtained by the ply twist is used as the fineness D of the fiber bundle to be twisted. When the yarn 16 has three layers of twist, the fineness of the temporary strand 19 obtained by the first twist is used as the fineness D of the fiber bundle to be twisted in calculating the twist coefficient K of the first twist. In calculating the twist coefficient K of the middle twist, the fineness of the strand 17 obtained by the middle twist is used as the fineness D of the fiber bundle to be twisted. In calculating the twist coefficient K of the ply twist, the fineness of the yarn 16 obtained by the ply twist is used as the fineness D of the fiber bundle to be twisted.

In this toothed belt 10, as shown in FIGS. 4A and 4B, each filament in the strand 17 included in the yarn 16 is coated with a converging coating layer 20 made of a sizing agent. Strand 17 comprises a number of filaments 18 and a converging coating layer 20 covering each filament 18 . The yarn 16 is obtained by twisting a plurality of the strands 17 together.
In this toothed belt 10, since the converging coating layer 20 exists between the filaments 18, the filaments 18 are prevented from being directly rubbed against each other, and the movement of the filaments 18 is suppressed. Since the friction of the carbon filaments is suppressed, the toothed belt 10 prevents the core wires 13 from being reduced in strength due to wear of the carbon filaments.

As shown in FIG. 2, the surface of the yarns 16 included in the cord 13 is covered with an adhesive coating layer 21 made of adhesive. The cord 13 comprises yarns 16 and an adhesive coating layer 21 covering the yarns 16 .
In this toothed belt 10 , the adhesive coating layer 21 constrains movement of the strands 17 contained in the yarns 16 . Movement of not only the filaments 18 contained in the strands 17 but also the strands 17 contained in the yarn 16 is restrained. Since the friction of the carbon filaments is suppressed, the toothed belt 10 prevents the core wires 13 from being reduced in strength due to wear of the carbon filaments.

Both sizing agents and adhesives are emulsions in which an epoxy group-containing compound and a curing agent are dispersed in water. In this toothed belt 10, both the sizing agent and the adhesive contain an epoxy group-containing compound and a curing agent as main agents, and the solid content ratio of the main agents is preferably 80% by mass or more.
In this case, the converging coating layer 20 of sizing agent sufficiently constrains the filaments 18 contained in the strands 17 . Further, an adhesive coating layer 21 of adhesive sufficiently constrains the strands 17 contained in the yarn 16 . In this toothed belt 10, friction of carbon filaments is suppressed. Therefore, the reduction in strength of the core wire 13 due to wear of the carbon filaments is prevented.

The above-mentioned solid content ratio is expressed by the ratio of the total mass of the main agent, that is, the epoxy group-containing compound and the curing agent, to the total mass of solid content obtained by drying the sizing agent or adhesive.

From the viewpoint that the sizing agent or adhesive can effectively contribute to the suppression of movement of the filaments 18, the amount of the curing agent is preferably 5 to 50 mol per 1 mol of the epoxy group in the epoxy group-containing compound.

Examples of the above epoxy group-containing compounds include sorbitol polyglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, trimethylolpropane polyglycidyl ether, and the like. Among these, polyglycerol polyglycidyl ether is preferred.

The curing agent is preferably an isocyanate curing agent or an amine curing agent.
As a result, the converging coating layer 20 made of the sizing agent effectively constrains the carbon filaments contained in the strands 17 . In addition, an adhesive coating layer 21 effectively restrains the strands 17 contained in the yarn 16 . In this toothed belt 10 , not only the movement of the filaments 18 contained in the strands 17 but also the movement of the strands 17 contained in the yarns 16 are restrained. Since the friction of the carbon filaments is suppressed, in the toothed belt 10, deterioration of strength of the core wire due to wear of the carbon filaments is prevented.

In this toothed belt 10, examples of isocyanate-based curing agents include naphthalene diisocyanate, isophorone diisocyanate, 4,4′-diphenylmethane diisocyanate, toluene-2,4-diisocyanate, xylylene diisocyanate, tolylene diisocyanate, and polymethylene polyphenyl diisocyanate. , hexamethylene diisocyanate, and the like. Among these, 4,4'-diphenylmethane diisocyanate is preferred.
A commercial item can also be used as an isocyanate-type hardening|curing agent. Examples of commercially available isocyanate curing agents include "Grilbond IL-6" manufactured by EMS.

In the toothed belt 10, examples of the amine-based curing agent include diamine compounds, compounds having an oxazole ring, and imidazole-based compounds. Among these, imidazole compounds are preferred.
Commercially available products can be used as the amine curing agent. Commercially available products of this amine-based curing agent include, for example, "Curesol" manufactured by Shikoku Kasei Co., Ltd.

This toothed belt 10 uses an aqueous solution containing resorcin and formaldehyde and having a solid content ratio of 80% by mass or more, for example, instead of an emulsion containing an epoxy group-containing compound and a curing agent as the sizing agent. be able to.
This aqueous solution is also called an RF liquid, and the solid content ratio of the main agent is represented by the solid content ratio of the initial condensate of resorcinol and formaldehyde.
Regarding the precondensate (RF) of resorcin (R) and formaldehyde (F) in the RF liquid, the molar ratio (R/F) of resorcin (R) to formaldehyde (F) is, for example, 1/3 to 1/0. 5.
Even if an RF liquid is used as a sizing agent, the sizing coating layer 20 prevents the filaments 18 from directly rubbing against each other and also suppresses the movement of the filaments 18 . Since the friction of the carbon filaments is suppressed, the toothed belt 10 prevents the core wires 13 from being reduced in strength due to wear of the carbon filaments. Furthermore, in this case, a softer converging coating layer 20 is constructed as compared with the case where the solution containing the epoxy group-containing compound and the curing agent is used as the converging agent. Therefore, although the filament 18 is restrained by the converging coating layer 20, the filament 18 can move slightly. In this toothed belt 10, abrasion caused by rubbing of the carbon filaments is effectively prevented, and fatigue bending resistance is improved.

In this toothed belt 10, the RF liquid as a sizing agent can contain chemicals such as latex within a range that does not impair the function.
Examples of the latex include vinylpyridine/styrene/butadiene rubber latex (VP/SBR), styrene/butadiene rubber latex (SBR), natural rubber latex (NR), chloroprene rubber latex (CR), and chlorosulfonated polyethylene rubber latex. (CSM), 2,3-dichlorobutadiene rubber latex (2,3-DCB), hydrogenated nitrile rubber latex (H-NBR), carboxylated hydrogenated nitrile rubber latex, butadiene rubber latex (BR), nitrile rubber latex ( NBR) and the like. The sizing agent can contain one or more of these.

When the sizing agent is an aqueous solution comprising the precondensate of resorcin and formaldehyde and the latex described above, this sizing agent is also referred to as an RFL aqueous solution. In this case, the total solid content ratio of the initial condensate content of resorcin and formaldehyde in the RFL aqueous solution and the latex-derived solid content is, for example, 10% by mass or more and 30% by mass or less.
Regarding the precondensate (RF) of resorcin (R) and formaldehyde (F) in the RFL aqueous solution, the molar ratio (R/F) of resorcin (R) to formaldehyde (F) is, for example, 1/3 to 1/0. 5. The mass ratio (RF/L) of the initial condensate (RF) of resorcin (R) and formaldehyde (F) in the RFL aqueous solution to the latex-derived solid content (L) is, for example, 1/10 to 1/0, preferably is around 1/6.

As noted above, strands 17 include carbon filaments. In this toothed belt 10, the strands 17 can contain polyamide filaments made of polyamide fibers in addition to carbon filaments.
Polyamide filaments act as a binder between carbon filaments. Since the friction of the carbon filaments is suppressed, this toothed belt prevents the reduction in the strength of the cord due to the wear of the carbon filaments.

In this toothed belt 10, if the filaments 18 contain polyamide filaments other than carbon filaments, the strands 17 or yarns 16 containing these polyamide filaments are preferably heat-treated.
When a polyamide filament is heated above its melting point, the polyamide filament melts. This allows the polyamide filaments to enter between the surrounding carbon filaments. Molten polyamide filaments can effectively act as a binder between carbon filaments. The molten polyamide filaments constrain filaments 18 . Since the friction of the carbon filaments is suppressed, the toothed belt 10 prevents the core wires 13 from being reduced in strength due to wear of the carbon filaments. From this point of view, in this toothed belt 10, the strands 17 preferably contain molten polyamide filaments in addition to the carbon filaments.

In the toothed belt 10, when the strands 17 contain carbon filaments and polyamide filaments, the polyamide filaments can effectively function as a binder. The volume percentage of the polyamide filaments is preferably 3-12% by volume.

Examples of the polyamide (nylon) constituting the polyamide filament include nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, and nylon 1212.

In the toothed belt 10, structurally, shear strain is likely to occur in the vicinity of the boundary between the back rubber portion 11a and the tooth rubber portion 11b. In particular, as described above, from the viewpoint of suppressing the occurrence of back cracks, the back rubber portion 11a is made of a soft thermoplastic elastomer composition, and the tooth rubber portion 11b is made of a hard thermoplastic elastomer composition compared to the back rubber portion 11a. When it is composed of an elastomer composition, the vicinity of this boundary is susceptible to shear strain due to the difference in rigidity.
The core wire 13 of the toothed belt 10 is arranged on the inner peripheral side of the back rubber portion 11a. In other words, the core wire 13 is located near the boundary between the back rubber portion 11a and the tooth rubber portion 11b. Therefore, the interface between the cord 13 and the back rubber portion 11a is susceptible to this shear strain. However, the yarns 16 included in cord 13 have two or more layers of twist, as described above. This yarn 16 can effectively mitigate the effects of shear strain described above. Therefore, the state in which the cord 13 is held by the back rubber portion 11a is stably maintained. In other words, peeling of the core wire 13 from the back rubber portion 11a is effectively prevented. The toothed belt 10 maintains a state suitable for high-load transmission over a long period of time.

(Production method)
This manufacturing method will be described with reference to FIGS.
FIG. 5 is a partial cross-sectional view of a belt mold used in the method of manufacturing a toothed belt. 6 to 8 are diagrams for explaining the manufacturing steps of the manufacturing method.
The manufacturing method has a material preparation process, a lamination process, a molding process, and a finishing process.

<Material preparation process>
≪Elastomer sheet≫
A thermoplastic elastomer sheet for the back rubber portion and a thermoplastic elastomer sheet for the tooth rubber portion are prepared. Each elastomer sheet is obtained, for example, by preparing a thermoplastic elastomer composition containing TPAE or TPC as an elastomer component and necessary additives, and molding this into a sheet by extrusion molding or the like.
Further, the thermoplastic elastomer sheet for the back rubber portion and the thermoplastic elastomer sheet for the tooth rubber portion may be formed 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 molded in this step may be temporarily wound up, or may be supplied as it is to the next step.

≪Reinforcing cloth≫
A reinforcing cloth (tooth covering material) having a tooth profile corresponding to the shape of the belt teeth is prepared.
The reinforcing cloth is placed along the heated mold, which has recesses of the same shape as the teeth of the belt, and a soft elastic body is pressed from the opposite side of the mold to mold the reinforcing cloth into a toothed shape. .
The profiled reinforcing fabric may then be formed into a tubular shape. If desired, the reinforcement fabric can be subjected to a bonding treatment such as an RFL treatment.

≪Core wire≫
A core wire 13 is prepared by subjecting a carbon filament to a predetermined twist, bonding treatment, or the like. Here, it is preferable to prepare an S-twisted core wire and a Z-twisted core wire as a pair of core wires.
A bundle of filaments 18 is twisted to form a strand 17 . When each filament 18 is coated with the converging coating layer 20, the bundle of filaments 18 is immersed in a solution containing a sizing agent, the sizing agent is applied to the entire surface of each filament 18, and then the bundle is twisted to form a strand. 17. As a result, strands 17 impregnated with a sizing agent between filaments 18 are obtained. After that, the strand 17 is heated to volatilize the dispersion medium contained in the sizing agent and dry the sizing agent. This results in a strand 17 containing filaments 18 coated with a converging coating layer 20 (thickness=0.05-0.35 μm) of a sizing agent. The heating temperature in the sizing agent treatment is set to, for example, 180° C. or higher and 250° C. or lower. The heating time is set to, for example, 3 minutes or more and 10 minutes or less.

A yarn 16 is formed by twisting a plurality of strands 17 together. When the yarn 16 is coated with the adhesive coating layer 21, the yarn 16 is immersed in a solution containing the adhesive to apply the adhesive to the entire surface of the strands 17. FIG. As a result, a coating layer of adhesive is formed on the surface of the yarn 16 . Thereafter, the coating layer is heated to volatilize the dispersion medium contained in the coating layer, and the coating layer is dried. As a result, the core wire 13 is obtained in which the adhesive coating layer 21 (thickness=0.15 to 0.8 μm) made of adhesive is formed on the surface of the yarn 16 . The heating temperature in the adhesive treatment is set to, for example, 180° C. or higher and 250° C. or lower. The heating time is set to, for example, 3 minutes or more and 10 minutes or less.

When the filaments 18 included in the yarn 16 include polyamide filaments, the core wire 13 is subjected to heat treatment. By this heat treatment, the melted polyamide filaments enter between the carbon filaments, and the core wire 13 containing the melted polyamide filaments is obtained. This heat treatment may be performed during drying in the adhesive treatment. In this case, the heating temperature and time in this heat treatment are considered for the heating temperature and time during drying.

<Lamination process>
FIG. 5 is a partial cross-sectional view showing part of the belt molding die 30. As shown in FIG.
The belt forming die 30 is cylindrical and has an outer peripheral surface in which a plurality of axially extending tooth forming grooves 31 are arranged at intervals in the circumferential direction.

As shown in FIG. 6, the outer peripheral surface of the belt forming die 30 is covered with a toothed tubular reinforcing cloth 14, and a pair of core wires 13 are spirally wound thereon.
Then, the thermoplastic elastomer sheet 11b' for the tooth rubber portion and the thermoplastic elastomer sheet 11a' for the back rubber portion are wound thereon in this order. The number of layers of each wound sheet may be one or two or more depending on the dimensions of the belt to be produced.
Furthermore, a release paper or a release film (not shown) is wound as necessary.
Thereby, the laminate S′ is molded on the belt molding die 30 .

<Molding process>
A jacket having a rubber sleeve 32 on its inner surface and a closed space between the sleeve 32 and the main body is placed over the laminate S'. As a result, as shown in FIG. 7, the laminated body S' on the belt mold 30 is covered with the rubber sleeve 32. Next, as shown in FIG.
High-pressure steam is introduced into the interior of the mold 30 around which the laminate S' is wound and the space between the jacket to heat and compress. As a result, the thermoplastic elastomer forming the thermoplastic elastomer sheets 11a' and 11b' is passed through the gaps between the cords and poured into the tooth forming grooves 31, thereby forming the belt teeth 12 as shown in FIG. .
At this time, the temperature of the high-pressure steam is set to a temperature equal to or higher than the temperature at which the thermoplastic elastomer flows. In addition, when the elastomer component of the thermoplastic elastomer sheet is TPAE, the temperature of the high-pressure steam is set to 170° C. or higher.

After the belt teeth 12 are formed, the jacket and mold 30 are cooled with water or the like to lower the temperature of the elastomer to 100° C. or less, and then the mold 30 and molded body S are removed from the jacket. Furthermore, when the temperature of the molded body S is 40° C. or higher, the molded body S is further cooled, and when the temperature of the molded body S drops below 40° C., the molded body S is removed from the mold 30 .

<Finishing process>
The toothed belt 10 is obtained by cutting the molded article S taken out into a specified width and separating it.
Through such steps, the toothed belt 10 in which the belt body 11 is made of the thermoplastic elastomer composition can be manufactured.

<Others>
If the thermoplastic elastomer sheet 11b' for the tooth rubber and the thermoplastic elastomer sheet 11a' for the back rubber are different in hardness, the reinforcing cloth 14 and the core wire are placed on the outer peripheral surface of the belt molding die 30. 13 and the thermoplastic elastomer sheet 11b' for the tooth rubber are laminated, then heated and compressed by the above-described high-pressure steam to form the belt teeth, cooled once, and then the thermoplastic elastomer sheet for the back rubber. 11a' is wound thereon, heated and compressed again by high-pressure steam, then cooled again, and finally finished, to produce a toothed belt.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples.

Here, a toothed belt with a tooth type of S8M was produced and its performance was evaluated.
The toothed belt of each example was manufactured using the manufacturing method already explained above.
A thermoplastic elastomer composition, cords, and reinforcing cloth for forming the belt body (back rubber portion and tooth rubber portion) were prepared as follows.

(Thermoplastic elastomer composition)
The following thermoplastic elastomer composition was prepared. Both thermoplastic elastomer compositions are commercially available.

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.
(A2) PEBAX (registered trademark) 2533SP-01 manufactured by Arkema was used. The hardness of this thermoplastic elastomer composition is 27.
PEBAX has a polyol as the soft segment.

TPO: Polyolefin Thermoplastic Elastomer Composition Thermorun (registered trademark) QT85KB manufactured by Mitsubishi Chemical Corporation was used. The hardness of this thermoplastic elastomer composition is 31.

TPU: Polyurethane Thermoplastic Elastomer Composition Miractran (registered trademark) E490 manufactured by Miractran Japan Co., Ltd. was used. The hardness of this thermoplastic elastomer composition is 43.

(reinforcement cloth)
An RFL-treated nylon canvas was prepared as a reinforcing cloth.
In this case, a woolly textured nylon canvas with 6,6-nylon fibers for the warp and 6,6-nylon fibers for the weft was prepared.
Separately, an RFL aqueous solution (latex is vinylpyridine/styrene/butadiene rubber latex) was prepared.

(Core wire)
A carbon filament (manufactured by Teijin Tenax Co., Ltd., filament diameter 7 μm), a filament made of nylon fiber as a polyamide filament (manufactured by Asahi Kasei Corporation, filament diameter 19 μm), and a filament made of glass fiber (manufactured by NSG Co., filament diameter 9 μm) were prepared. prepared the core wires shown in the table.
In each table, "T" in the column of twist type indicates ply twist, "LT" indicates Lang twist, and "ST" indicates single twist.
The number of filaments contained in each cord was set to 15,000.
The CF ratio in the table represents the ratio of the volume of all carbon filaments to the volume of all filaments contained in the yarn. The PA ratio expresses the ratio of the volume of all polyamide filaments to the volume of all filaments contained in the yarn.
The following processing liquids A, B and C were prepared. In the columns of sizing agents and adhesives in each table, the treatment liquid used is indicated by "A", [B] or "C".
Treatment liquid A
Using "Denacol EX-521" manufactured by Nagase Chemtech Co., Ltd. and "Curesol 2E4MZ-CN" manufactured by Shikoku Kasei Co., Ltd., a treatment liquid A containing an epoxy group-containing compound and an amine-based curing agent was prepared. The solid content ratio of the epoxy group-containing compound and the curing agent in this treatment liquid A was 10% by mass. The amount of the amine-based curing agent was set to 10 mol per 1 mol of epoxy group in the epoxy group-containing compound.
Treatment liquid B
"Denacol EX-521" manufactured by Nagase Chemtech Co., Ltd., "Cure Sol 2E4MZ-CN" manufactured by Shikoku Kasei Co., Ltd., and "Grilbond IL-6" manufactured by EMS Co., Ltd., epoxy group-containing compounds, amine-based curing agents and A treatment liquid B containing an isocyanate curing agent was prepared. The solid content ratio of the epoxy group-containing compound and the curing agent in this treatment liquid B was 30% by mass. The amount of the curing agent consisting of the amine-based curing agent and the isocyanate-based curing agent was set to 10 mol with respect to 1 mol of the epoxy group in the epoxy group-containing compound. The functional group ratio of epoxy groups to isocyanate groups was set to 1:1 on a molar basis.
・Processing liquid C
As the treatment liquid C, an RF liquid was prepared. The solid content ratio of the precondensate of resorcinol and formaldehyde was 100% by mass. The molar ratio (R/F) of resorcin (R) to formalin (F) was 1/1.5.

[Example 1]
The TPAE (A1) is used for the back rubber portion and the tooth rubber portion, the nylon canvas is used as the reinforcing cloth, and the core wire containing the carbon filament is used. ) manufactured a toothed belt with a tooth type of S8M. The belt width was 8 mm and the belt length was 1200 mm.
For the cord, a yarn of the type shown in FIG. 4A was prepared, specifically a plied type yarn having two layers of twist consisting of a ply and a ply.
The number of filaments included in each strand included in the yarn was set to 3000. All of the filaments were composed of carbon filaments.
After a bundle of filaments was immersed in treatment liquid A as a sizing agent, the bundle of filaments was pre-twisted to form a strand. This strand was heat-treated at a temperature of 180° C. for 5 minutes. This formed a converging coating layer filling between the filaments of the strand. The twist factor for the first twist was set to 40.
Five strands on which the converging coating layer was formed were prepared and ply-twisted to constitute a yarn. The twist factor for the ply twist was set to 40.
Using treatment liquid B as an adhesive, the yarn was treated with an adhesive to form an adhesive coating layer on the surface of the yarn. The heating temperature in this treatment was set at 220° C., and the heating time was set at 10 minutes.

[Example 2]
A toothed belt of Example 2 was obtained in the same manner as in Example 1, except that the twist type of the yarn was Lang twist.

[Example 3]
Example except that the yarn of the core wire was changed to a yarn having the configuration shown in FIG. A toothed belt of Example 3 was obtained in the same manner as in Example 1.
In this Example 3, each strand in the yarn consisted of three temporary strands. The number of filaments contained in each temporary strand was set to 1000. As in Example 1, all filaments were made of carbon filaments.
After the filament bundle was immersed in the treatment liquid A as a sizing agent, the filament bundle was pre-twisted to form a temporary strand. The twist factor for the first twist was set to 5.
Three temporary strands were center-twisted to form a strand. The direction of the middle twist was the same as the direction of the first twist, and the twist coefficient of the middle twist was set to 35.
This strand was heat-treated at a temperature of 180° C. for 5 minutes. This formed a converging coating layer filling between the filaments of the strand.
Five strands on which the converging coating layer was formed were prepared and ply-twisted to constitute a yarn. The direction of the ply twist was opposite to the direction of the middle twist, and the twist coefficient of the ply twist was set to 40.
Using treatment liquid B as an adhesive, the yarn was treated with an adhesive to form an adhesive coating layer on the surface of the yarn. The heating temperature in this treatment was set at 220° C., and the heating time was set at 10 minutes.

[Comparative Example 1]
A toothed belt of Comparative Example 1 was obtained in the same manner as in Example 1, except that the yarn of the cord was changed to a yarn (not shown) formed by twisting a bundle of 15,000 filaments.
In Comparative Example 1, treatment liquid A was used as a sizing agent to form a converging coating layer that fills between the filaments of the yarn. The heating temperature in the treatment was set to 180° C., and the heating time was set to 5 minutes.
The yarn on which the converging coating layer was formed was further treated with an adhesive using treatment liquid B as an adhesive to form an adhesive coating layer on the surface of this yarn. The heating temperature in this treatment was set at 220° C., and the heating time was set at 10 minutes.
The yarn twist factor was set at 80. The twist level of this yarn is 1.

[Comparative Example 2]
A toothed belt of Comparative Example 2 was obtained in the same manner as in Example 1, except that filaments made of the glass fibers described above were used.

[Comparative Examples 3-4]
Toothed belts of Comparative Examples 3-4 were obtained in the same manner as in Example 1 except that the thermoplastic elastomer compositions of the back rubber portion and tooth rubber portion were as shown in Table 1 below.

[Examples 4-1 to 4-5]
Toothed belts of Examples 4-1 to 4-5 were obtained in the same manner as in Example 1, except that the twist coefficient of the ply twist was set as shown in Table 2 below.

[Examples 5-1 to 5-5]
Toothed belts of Examples 5-1 to 5-5 were obtained in the same manner as in Example 2, except that the twist coefficient of the ply twist was set as shown in Table 3 below.

[Examples 6-1 to 6-5]
Toothed belts of Examples 6-1 to 6-5 were obtained in the same manner as in Example 3 except that the twist coefficient of the ply twist was set as shown in Table 4 below.

[Example 7-1]
A toothed belt of Example 7-1 was obtained in the same manner as in Example 1, except that the sizing agent treatment was not performed.

[Example 7-2]
A toothed belt of Example 7-2 was obtained in the same manner as in Example 1, except that the adhesive treatment was not performed.

[Example 7-3]
A toothed belt of Example 7-3 was obtained in the same manner as in Example 1, except that treatment liquid C was used as the sizing agent and treatment liquid B was used as the adhesive.

[Example 8-1]
A toothed belt of Example 8-1 was obtained in the same manner as in Example 2, except that the sizing agent treatment was not performed.

[Example 8-2]
A toothed belt of Example 8-2 was obtained in the same manner as in Example 2, except that the adhesive treatment was not performed.

[Example 9-1]
A toothed belt of Example 9-1 was obtained in the same manner as in Example 3, except that the sizing agent treatment was not performed.

[Example 9-2]
A toothed belt of Example 9-2 was obtained in the same manner as in Example 3, except that the adhesive treatment was not performed.

[Example 10-1]
Toothed Example 10-1 was produced in the same manner as in Example 1 except that the filaments contained in the strands were composed of carbon filaments and polyamide filaments, and the CF ratio and PA ratio were as shown in Table 6 below. got the belt.

[Examples 10-2 to 10-3]
Toothed belts of Examples 10-2 to 10-3 were obtained in the same manner as in Example 10-1 except that the CF ratio and PA ratio were as shown in Table 6 below.

[Example 10-4]
Toothed Example 10-4 was produced in the same manner as in Example 2 except that the filaments contained in the strands were composed of carbon filaments and polyamide filaments, and the CF ratio and PA ratio were as shown in Table 6 below. got the belt.

[Example 11-1]
A toothed belt of Example 11-1 was obtained in the same manner as in Example 1, except that treatment liquid B was used as the sizing agent.

[Example 11-2]
A toothed belt of Example 11-2 was obtained in the same manner as in Example 3, except that treatment liquid B was used as the sizing agent.

[Example 12]
A toothed belt of Example 12-1 was obtained in the same manner as in Example 1 except that the above TPAE (A2) was used for the back rubber portion and the above TPAE (A1) was used for the tooth rubber portion.

(Evaluation method)
Durability Tests 1 to 3 were performed to evaluate the durability of the toothed belts produced in Examples and Comparative Examples. The results are shown in Tables 1-6.

<Durability test 1>
Durability test 1 is a test for evaluating durability under standard running conditions. Examples 1, 7-1 to 7-3, 8-1 to 8-2, 9-1 to 9-2, 10-1 to 10-4, 11-1 to 11-2 and 12, and Comparative Examples The toothed belts manufactured in 3-4 were tested.
FIG. 9 shows the belt running tester 80 used in the durability test 1. As shown in FIG.
The belt running tester 80 includes a drive pulley 81 with 22 teeth and an 8M tooth profile, and a driven pulley 82 with 33 teeth and an 8M tooth profile provided on the right side of the driving pulley 81 . The driven pulley 82 is provided movably to the left and right so as to be able to apply an axial load (dead weight).

Examples 1, 7-1 to 7-3, 8-1 to 8-2, 9-1 to 9-2, 10-1 to 10-4, 11-1 to 11-2 and 12, and Comparative Examples The toothed belt 110 manufactured in each of 3 and 4 is wound between the drive pulley 81 and the driven pulley 82 of the belt running tester 80, and an axial load of 608 N is applied to the right side of the driven pulley 82. A belt tension was applied, a rotational load of 34.2 N·m was applied to the driven pulley 82, and the driving pulley 81 was rotated at a rotational speed of 4200 times per minute at room temperature to run the belt. The running of the belt is periodically stopped to visually check for cracks on the back of the back rubber, wire sticking out, stripping of the wire, etc., and the belt runs until the occurrence of the failure is confirmed. time was measured. The maximum belt running time was set to 1000 hours.
Moreover, when tooth jumping occurred even though failure did not occur, the test was terminated at that point.

<Durability test 2>
Durability test 2 is a test for evaluating durability under high load conditions. The toothed belts manufactured in Examples 1, 4-1 to 4-5, 5-1 to 5-5, 6-1 to 6-5 and 12, and Comparative Example 2 were tested.
FIG. 10 shows the belt running tester 90 used in the second durability test.
The belt running tester 90 includes a driving pulley 91 having 24 teeth and an 8M tooth profile, and a driven pulley 92 having 36 teeth and an 8M tooth profile provided on the right side of the driving pulley 91 . The driven pulley 92 is provided movably to the left and right so as to be able to apply an axial load (dead weight).

For the toothed belts 120 manufactured in Examples 1, 4-1 to 4-5, 5-1 to 5-5, 6-1 to 6-5 and 12, and Comparative Example 2, belt running tester 90 between the driving pulley 91 and the driven pulley 92, a shaft load of 520 N is applied to the right side of the driven pulley 92 to give belt tension, and a rotational load of 39.2 N·m is applied to the driven pulley 92. , and the driving pulley 91 was rotated at a rotational speed of 3000 times per minute at room temperature to run the belt. Then, the running of the belt was periodically stopped to visually confirm the occurrence of failures such as tooth chipping and wire breakage, and the belt running time until failure was confirmed was measured.
When a failure occurred even though cracks did not occur, the test was terminated at that point.

<Durability test 3>
Durability test 3 is a test for evaluating the bending fatigue resistance of the toothed belt using a small pulley. Examples 1 to 3, 4-1 to 4-5, 5-1 to 5-5, 6-1 to 6-5, 7-3, 10-2 to 10-3, 11-1 to 11-2 and 12, and the toothed belts manufactured in Comparative Example 1.
FIG. 11 shows the belt running tester used in durability test 3. FIG.
The belt running tester 100 includes a driving pulley 101 with 22 teeth and an 8M tooth profile, and three driven pulleys 102 with 22 teeth and an 8M tooth profile. The driven pulley 102 a is provided obliquely downward to the right of the drive pulley 101 . The driven pulley 102b is provided diagonally to the left of the driven pulley 102a and below the driving pulley 101. As shown in FIG. The driven pulley 102c is provided obliquely above the driven pulley 102b and to the left of the driven pulley 102a. The driven pulley 102b is configured to be vertically movable so as to apply an axial load (dead weight). In this belt running tester 100, the drive pulley 101 and the three driven pulleys 102 are arranged so that the contact angle between the toothed belt and the drive pulley 101 is 120 degrees.

Examples 1 to 3, 4-1 to 4-5, 5-1 to 5-5, 6-1 to 6-5, 7-3, 10-2 to 10-3, 11-1 to 11-2 and 12, and the toothed belt 130 manufactured in each of Comparative Example 1, is wound around the drive pulley 101 and three driven pulleys 102 of the belt running tester 100, and the shaft of 392 N downward to the driven pulley 102c A load was applied to give belt tension, and the driving pulley 101 was rotated at a rotational speed of 5500 times per minute at room temperature to run the belt. Then, the running of the belt was periodically stopped to check whether or not the core wire was cut, and the belt running time until the core wire was cut was measured.

As shown in Tables 1 to 6, according to the toothed belts according to the embodiments of the present invention, the generation of cracks on the back surface of the belt is suppressed. Furthermore, wear of the belt teeth is suppressed even when high-load transmission is performed. Further, even when used with a small pulley in which a large compressive strain acts on the cord, the cord is prevented from being cut due to bending fatigue.
With this toothed belt, a state suitable for high-load transmission is maintained over a long period of time. This toothed belt has excellent bending fatigue resistance and is suitable for high-load transmission.

INDUSTRIAL APPLICABILITY The present invention is useful in the technical field of toothed belts in which a plastic elastomer composition is used as a material for the tooth rubber portion and the back rubber portion.

REFERENCE SIGNS LIST 10, 110, 120, 130 toothed belt 11 belt body 11a back rubber portion 11b tooth rubber portion 12 belt teeth 13 core wire 14 reinforcing cloth (tooth portion covering material)
15 Tooth Bottom 16 Yarn 17 Strand 18 Filament 19 Temporary Strand 20 Converging Coating Layer 21 Adhesive Coating Layer 30 Belt Mold 31 Tooth Forming Groove 32 Rubber Sleeve 80, 90, 100 Belt Tester 81, 91, 101 Drive Pulley 82, 92 , 102 driven pulley

Claims (15)

a flat belt-shaped back rubber portion; and a plurality of tooth rubber portions disposed on the inner peripheral side of the back rubber portion and integrally provided with the back rubber portion to constitute belt teeth, a belt body in which both the rubber portion and the tooth rubber portion are made of a thermoplastic elastomer composition;
a core wire arranged and embedded so as to form a spiral having a pitch in the width direction of the belt in the portion on the inner peripheral side of the back rubber portion;
a tooth portion covering material covering the plurality of tooth rubber portions provided on the inner peripheral side of the belt body;
with
In the thermoplastic elastomer composition, the elastomer component is a thermoplastic polyamide elastomer (TPAE) or a thermoplastic polyester elastomer (TPC),
The thermoplastic elastomer composition constituting the back rubber portion has a hardness of 25 to 70,
The thermoplastic elastomer composition constituting the tooth rubber portion has a hardness of 40 to 70, and the thermoplastic elastomer composition constituting the back rubber portion has a hardness equal to or higher than that of the thermoplastic elastomer composition,
The core wire comprises yarn having two or more layers of twist,
the yarn comprises two or more strands;
A toothed belt in which each strand is formed by twisting a large number of filaments including carbon filaments made of carbon fibers. The toothed belt according to claim 1, wherein the elastomer component of said thermoplastic elastomer composition is thermoplastic polyamide elastomer (TPAE). 3. The toothed belt according to claim 1 or 2, wherein the yarn has two layers of twist consisting of a ply and a ply and is twisted with a ply. 3. The toothed belt according to claim 1 or 2, wherein the yarn has two layers of twist consisting of a ply and a ply and is twisted with Lang twist. 3. The toothed according to claim 1 or 2, wherein the yarn has three layers of twist consisting of a ply twist, a middle twist and a ply twist, and the direction of the ply twist and the direction of the middle twist are the same. belt. 6. The toothed belt according to any one of claims 1 to 5, wherein the yarn has a total twist factor of more than 30 and 120 or less in each twist layer. 7. The toothed belt according to claim 6, wherein the twist factor in the ply twist of the yarn is 100 or less. 8. The toothed belt according to claim 7, wherein the yarn has a ply twist with a twist coefficient of 30 or more and 60 or less. The toothed belt according to any one of claims 10 to 12, wherein said strands contain polyamide filaments made of polyamide fibers. 10. The toothed belt according to claim 9, wherein the ratio of the volume of the polyamide filaments to the sum of the volume of the carbon filaments and the volume of the polyamide filaments in the strand is 3 to 12% by volume. each filament in the strand is coated with a converging coating layer of a sizing agent;
The toothed belt according to any one of claims 1 to 10, wherein the sizing agent contains an epoxy group-containing compound and a curing agent, and has a solid content ratio of 80% by mass or more. The toothed belt according to claim 11, wherein the curing agent is an isocyanate curing agent or an amine curing agent. each filament in the strand is coated with a converging coating layer of a sizing agent;
The toothed belt according to any one of claims 1 to 10, wherein the sizing agent contains resorcin and formaldehyde and has a solid content ratio of 80% by mass or more. the yarn is coated with an adhesive coating layer consisting of an adhesive;
The toothed belt according to any one of claims 1 to 13, wherein the adhesive contains an epoxy group-containing compound and a curing agent, and has a solid content ratio of 80% by mass or more. The toothed belt according to claim 14, wherein the curing agent is an isocyanate curing agent or an amine curing agent.

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