Toothed belt, toothed belt transmission mechanism, and method for manufacturing toothed belt

Abstract

The present invention relates to a toothed belt comprising a back portion in which core wires extending along the belt circumferential direction are embedded, and a plurality of tooth portions formed on the inner circumferential surface of the back portion at intervals in the belt circumferential direction, the toothed belt including a back rubber layer formed on the belt outer circumferential side of the core wires, and a tooth rubber layer formed on the belt inner circumferential side of the core wires, and a tooth cloth being laminated onto the inner circumferential surface of the tooth rubber layer, wherein a fluororesin-containing rubber layer formed from a crosslinked rubber composition containing a fluororesin is laminated onto the inner circumferential surface of the tooth cloth, and a resin film layer containing a thermoplastic resin is laminated onto the inner circumferential surface of the fluororesin-containing rubber layer.

Description

Toothed belt, toothed belt transmission mechanism, and method for manufacturing a toothed belt

[0001] The present invention relates to a toothed belt with high durability and jumping resistance, a toothed belt transmission mechanism using the same, and a method for manufacturing a toothed belt.

[0002] Power transmission belts are broadly classified into friction belts and meshing belts. Examples of friction belts include flat belts, V-belts, and V-ribbed belts, while an example of a meshing belt is a toothed belt. A toothed belt has a back portion with a core wire embedded approximately parallel to the belt's circumference, teeth arranged at predetermined intervals in the belt's circumference, and a toothed fabric that forms the surface of the teeth. The teeth of a toothed belt transmit power by engaging with a pulley that has grooves opposite to the teeth. Toothed belts do not slip with the pulley and can reliably transmit power even under high loads. In recent years, their use has increased in industrial machinery, internal combustion engines of automobiles, and rear-wheel drive systems of motorcycles. In particular, with the miniaturization of machinery and vehicles, there is a demand for toothed belts that can accommodate smaller sizes (compatible with smaller diameter pulleys and narrower widths). When a miniaturized toothed belt is used in the same environment as a conventional large toothed belt, a higher load is applied to the toothed belt. Therefore, while miniaturization is possible, there is a need for highly durable toothed belts that can withstand use under conditions where higher loads are applied.

[0003] An important factor in the durability of toothed belts is the rigidity (deformation resistance) of the teeth. During the process of meshing with a toothed pulley, repeated deformation of the teeth due to contact with the pulley can lead to malfunctions such as tooth skipping (jumping) and tooth chipping due to cracks in the tooth root. Tooth chipping is a type of failure in which a tooth falls off the belt body. It is thought that this occurs when repeated deformation of the teeth concentrates stress on the tooth root, causing a microscopic crack to form at the tooth root, and then that crack to grow. In particular, when toothed belts are used under conditions of high load, the stress concentrated on the tooth root becomes especially large, making it easy for cracks to form from the tooth root and lead to tooth chipping. More specifically, microscopic cracks that mainly occur on or near the surface of the tooth root often propagate (grow) into the tooth rubber that forms the tooth, causing tooth chipping.

[0004] Therefore, increasing the rigidity of the teeth is necessary to suppress deformation of the teeth. On the other hand, increasing the rigidity of the teeth also increases the bending rigidity of the belt, reducing its flexibility. As machinery and vehicles become smaller, toothed pulleys also become smaller (smaller in diameter), requiring high flexibility (suppleness) to wrap around the small-diameter pulley and provide good meshing. Meanwhile, even if a minute crack occurs, if it is possible to prevent the minute crack from growing and leading to tooth breakage, tooth breakage can be prevented.

[0005] In other words, in toothed belts, the rigidity (deformation resistance) of the teeth and the flexibility (suppleness) of the belt are in a conflicting relationship and difficult to achieve simultaneously. Therefore, a balanced formula is needed to achieve both, and if minute cracks occur due to prolonged use, it is necessary to suppress the growth of these cracks.

[0006] In particular, when toothed belts are used for high-load transmission in rear-wheel drive systems of motorcycles, the belt width needs to be narrowed to accommodate compact designs. Therefore, in high-load transmission applications in rear-wheel drive systems of motorcycles, it is necessary to maintain meshing performance under high loads even with narrowed widths, thereby ensuring resistance to jumping (high jumping torque). In addition, in high-load transmission applications in rear-wheel drive systems of motorcycles, jumping occurs due to a decrease in tension caused by belt stretching during the initial stages of travel. Therefore, it is also necessary to ensure tension retention to suppress jumping during the initial stages of travel. Furthermore, even in high-load transmission applications in rear-wheel drive systems of motorcycles, it is necessary to ensure resistance to bending fatigue in order to accommodate small-diameter pulleys.

[0007] The following documents disclose methods for improving the jumping resistance of toothed belts: Patent Document 1 and Patent Document 2.

[0008] Japanese Patent Publication No. 2023-16001 (Patent Document 1), which discloses a method for calculating and controlling the predicted value of jumping torque, states that the jumping torque increases when the value ES, which is the product of the Young's modulus E and cross-sectional area S of a toothed belt, is large, when the hardness of the teeth is high, and when the coefficient of friction of the teeth is small.

[0009] Japanese Patent Publication No. 2024-128945 (Patent Document 2) discloses a toothed belt characterized in that the teeth include a first rubber layer on the inner circumference containing short fibers and having a high modulus of elasticity, and a second rubber layer on the outer circumference having a low modulus of elasticity. The effects of the invention are described as being able to ensure jumping resistance, tension retention, and bending fatigue resistance even when the width is narrowed for high load transmission applications in the rear wheel drive of motorcycles, and examples using a carbon core wire with a high modulus of elasticity, a tooth fabric woven with polytetrafluoroethylene (PTFE) fibers with a low coefficient of friction, and tooth rubber with high hardness and tensile modulus of elasticity are described.

[0010] While the tooth cloth woven with fluorine-based fibers such as PTFE fibers used in Patent Document 2 is highly effective in reducing the coefficient of friction of the tooth, it requires a special weaving structure to prevent the fluorine-based fibers, which have poor adhesive properties, from being exposed on the tooth rubber side and reducing the adhesive strength, which has the problem of reducing cost-effectiveness.

[0011] As an alternative to tooth cloths woven with fluorine-based fibers, tooth cloths impregnated or coated with powdered fluororesin, such as those disclosed in the following literature, have been proposed.

[0012] Japanese Patent Publication No. 2000-310293 (Patent Document 3) discloses a toothed belt in which a rubber composition containing dispersed fluororesin is impregnated and coated onto a toothed cloth. Japanese Patent Publication No. 2002-103467 (Patent Document 4) discloses a toothed belt in which a fluorine-based paint is applied to one side of the toothed cloth. Japanese Patent Publication No. 2006-17264 (Patent Document 5) discloses a high-load toothed belt in which a glue rubber layer with a low-friction agent added is formed on the tooth surface side of the toothed cloth layer. Japanese Patent Publication No. 2006-84010 (Patent Document 6) discloses a toothed belt in which a treated cloth, in which polytetrafluoroethylene is blended in both a layer of raw canvas impregnated with rubber and a rubber layer formed on its surface that forms the pulley contact surface, is attached to the surface of the teeth.

[0013] Japanese Patent Publication No. 2023-16001, Japanese Patent Publication No. 2024-128945, Japanese Patent Publication No. 2000-310293, Japanese Patent Publication No. 2002-103467, Japanese Patent Publication No. 2006-17264, Japanese Patent Publication No. 2006-84010

[0014] However, in the toothed belts described in Patent Documents 3 to 6, while the effect of reducing the coefficient of friction of the teeth is high in the initial stages of belt use, the fluororesin and rubber composition containing fluororesin tend to scatter easily, making it difficult to reduce the coefficient of friction of the teeth or improve wear resistance over the long term. Furthermore, when the rubber composition containing fluororesin is applied to the tooth cloth, there is also the problem that it is difficult to improve the smoothness of the tooth surface. If the smoothness of the tooth surface is low, mud tends to adhere to the recesses, and as more mud accumulates on top of the attached mud, the engagement between the belt and pulley deteriorates, reducing durability and jumping resistance. Also, in the tooth cloth woven with PTFE fibers used in Patent Document 2, for example, if a double-woven canvas of PTFE fibers is used, mud tends to accumulate in the weave of the canvas, and a similar phenomenon occurs. Furthermore, the inventors also considered completely filling the weave of the canvas with a rubber composition containing fluororesin to make it smooth, but it was difficult to completely fill the weave and make it smooth.

[0015] Therefore, the object of the present invention is to provide a toothed belt with high durability and jumping resistance, a toothed belt transmission mechanism using the same, and a method for manufacturing a toothed belt.

[0016] Another object of the present invention is to provide a toothed belt that can improve durability and jumping resistance without using a special toothed fabric, a toothed belt transmission mechanism using the same, and a method for manufacturing a toothed belt.

[0017] Another object of the present invention is to provide a toothed belt that can be manufactured inexpensively and has excellent durability and jumping resistance, a toothed belt transmission mechanism using the same, and a method for manufacturing a toothed belt.

[0018] As a result of diligent research to achieve the above objectives, the present inventors have discovered that, in a toothed belt in which the inner surface of the tooth rubber layer is covered with tooth cloth, a toothed belt with high durability and jumping resistance can be provided by sequentially laminating a fluororesin-containing rubber layer and a resin film layer on the inner surface of the tooth cloth, and have completed the present invention.

[0019] In other words, the present invention includes the following embodiments.

[0020] Embodiment [1]: A toothed belt comprising a back portion in which a core wire extending along the circumferential direction of the belt is embedded, and a plurality of teeth formed on the inner circumferential surface of the back portion at intervals in the circumferential direction of the belt, the back rubber layer formed on the outer circumferential side of the belt with respect to the core wire, and a tooth rubber layer formed on the inner circumferential side of the belt with respect to the core wire, wherein a tooth cloth is laminated on the inner circumferential surface of the tooth rubber layer, a fluororesin-containing rubber layer formed of a crosslinked rubber composition containing fluororesin is laminated on the inner circumferential surface of the tooth cloth, and a resin film layer containing thermoplastic resin is laminated on the inner circumferential surface of the fluororesin-containing rubber layer.

[0021] Embodiment [2]: The toothed belt according to Embodiment [1], wherein the fluororesin is granular and has an average particle size of 1 to 100 μm.

[0022] Embodiment [3]: The toothed belt according to Embodiment [1] or [2], wherein the average thickness of the fluororesin-containing rubber layer is 10 to 100 μm.

[0023] Embodiment [4]: ​​The toothed belt according to any one of Embodiments [1] to [3], wherein the average thickness of the resin film layer is 20 to 120 μm.

[0024] Embodiment [5]: The toothed belt according to any one of Embodiments [1] to [4], wherein the melting point of the thermoplastic resin is 100 to 250°C.

[0025] Embodiment [6]: The toothed belt according to any one of Embodiments [1] to [5], wherein the thermoplastic resin comprises at least one selected from the group consisting of polyolefin resins, polyamide resins, and polyurethane resins.

[0026] Embodiment [7]: A toothed belt according to any one of Embodiments [1] to [6], wherein the tooth fabric does not contain fluorine-based fibers.

[0027] Embodiment [8]: The toothed belt according to any one of Embodiments [1] to [7], wherein the toothed fabric is a single-layer woven fabric.

[0028] Embodiment [9]: A toothed belt according to any one of Embodiments [1] to [8], wherein the core wire is a twisted cord of carbon fiber.

[0029] Aspect

[10] : The toothed rubber belt according to any one of the aspects [1] to [9], wherein the toothed rubber layer is formed of a first rubber layer on the inner peripheral side of the belt and a second rubber layer on the outer peripheral side of the belt, and the elastic modulus of the first rubber layer is greater than the elastic modulus of the second rubber layer.

[0030] Aspect

[11] : A toothed belt transmission mechanism including the toothed belt according to any one of the aspects [1] to

[10] and a pulley.

[0031] Aspect

[12] : The toothed belt transmission mechanism according to the aspect

[11] , which is used for a transmission application in the rear-wheel drive of a motorcycle.

[0032] Aspect

[13] : A method for manufacturing a toothed belt according to any one of the aspects [1] to

[10] , including a pre-forming step of producing a pre-form in which a first precursor for forming a resin film layer, a second precursor for forming a fluororesin-containing rubber layer, a third precursor for forming a tooth cloth, and a fourth precursor for forming a toothed rubber layer are laminated.

[0033] In the present application, the numerical range represented by "A to B" means "A or more and B or less", and is used in the sense of including the numerical values A and B at both ends.

[0034] In the present application, the "inner peripheral surface" means the "surface on the inner peripheral side of the belt" in each layer.

[0035] In the present invention, in a toothed belt in which the inner peripheral surface of the toothed rubber layer is covered with a tooth cloth, since the inner peripheral surface of the tooth cloth is sequentially laminated with a fluororesin-containing rubber layer and a resin film layer, a toothed belt with high durability and anti-jumping properties can be provided. In particular, without using a special tooth cloth (for example, a tooth cloth containing fluorine-based fibers or a tooth cloth having a multi-woven structure), the durability and anti-jumping properties of the toothed belt can be improved, so it is also excellent in economy.

[0036] Figure 1 is a schematic partial cross-sectional perspective view showing an example of the toothed belt of the present invention. Figure 2 is a schematic cross-sectional view of the toothed belt of Figure 1. Figure 3 is a partially enlarged view showing details of the inner circumferential surface of the toothed belt of Figure 1. Figure 4 is a schematic cross-sectional view illustrating the function of the resin film layer in the toothed belt of the present invention. Figure 5 is a schematic cross-sectional view showing another example of the toothed belt of the present invention. Figure 6 is a cross-sectional photograph of the toothed belt obtained in Example 2. Figure 7 is a photograph of the tooth fabric surface of the toothed belt obtained in Example 2. Figure 8 is a photograph of the tooth fabric surface of the toothed belt obtained in Example 15. Figure 9 is a photograph of the tooth fabric surface of the toothed belt obtained in Example 18.

[0037] <Toothed Belt> Below, an example of a toothed belt of the present invention will be described in detail, with reference to the attached drawings as necessary. In the following description, the same reference numeral may be used for elements (or components) that are identical or have common functions.

[0038] Figure 1 is a schematic partial cross-sectional perspective view showing an example of a toothed belt of the present invention, Figure 2 is a schematic cross-sectional view of the toothed belt of Figure 1, and Figure 3 is a partial enlarged view showing details of the inner circumferential surface of the toothed belt of Figure 1.

[0039] The toothed belt 1 in this example is an endless interlocking transmission belt, comprising a back portion 1c in which a core wire 4 extending in the belt circumferential direction (longitudinal direction) is embedded, and a plurality of teeth 1a provided at predetermined intervals on the inner circumferential surface of the back portion 1c and extending in the belt width direction, wherein the belt surface (inner circumferential surface) on the tooth portion side is composed of a laminate 2 of tooth fabric 2a, a fluororesin-containing rubber layer 2b, and a resin film layer 2c. The back portion 1c has a back rubber layer 5 disposed on the belt outer circumferential surface side of the core wire 4, and this back rubber layer 5 forms the belt outer circumferential surface. Furthermore, the toothed belt 1 of the present invention has a tooth rubber layer (rubber layer forming the teeth) 3 between the laminate 2 and the core wire 4 on the belt inner circumferential surface side of the core wire 4.

[0040] Between adjacent tooth portions 1a, there is a flat tooth root portion 1b, and the tooth portions 1a and tooth root portions 1b are alternately formed along the circumferential direction (belt longitudinal direction) on the inner surface of the belt. That is, the surface of the tooth portion 1a and the inner surface of the back portion 1c (i.e., the surface of the tooth root portion 1b) are made of the continuous laminate 2.

[0041] The present invention is characterized in that the inner surface of the tooth cloth 2a covering the inner surface of the tooth rubber layer 3 is further laminated sequentially with a fluororesin-containing rubber layer 2b and a resin film layer 2c. By having the inner surface of the belt, which is composed of the tooth portion 1a and the tooth root portion 1b, made of such a laminate 2, durability and jumping resistance can be improved with high economic efficiency.

[0042] The mechanism by which the inner surface of the belt is composed of such a laminate 2 improves durability and jumping resistance can be estimated as follows.

[0043] In other words, as shown in the shape of the interface between the tooth fabric 2a and the fluororesin-containing rubber layer 2b in Figures 4(a) to (c), the surface shape of the tooth fabric 2a is an uneven shape due to the weave of the woven fabric. As shown in Figure 4(a), when the fluororesin-containing rubber layer 2b is laminated on the inner surface of the tooth fabric 2a, the fluororesin-containing rubber penetrates the weave of the tooth fabric and improves the smoothness to some extent, but the effect is not sufficient. In contrast, as shown in Figure 4(b), the resin film layer 2c melts or softens due to heating during crosslinking, filling in the unevenness of the fluororesin-containing rubber layer 2b, and since the surface side is in contact with the mold, the smoothness is improved and the adhesion and accumulation of mud can be suppressed. Furthermore, although the resin film layer 2c wears down when the belt is run, it does not wear down completely, and as shown in Figure 4(c), the parts that have penetrated into the recesses of the fluororesin-containing rubber layer 2b remain. Therefore, smoothness can be ensured and jumping resistance can be maintained over a long period of time. Furthermore, in areas where the resin film layer 2c is worn away, the fluororesin-containing rubber layer 2b is exposed, reducing the coefficient of friction, thereby improving durability and resistance to jumping.

[0044] Furthermore, if the resin film layer 2c is laminated to the inner surface of the tooth fabric 2a without laminating the fluororesin-containing rubber layer 2b, it becomes difficult to adequately fill the irregularities of the weave, and the smoothness cannot be improved. In addition, the resin film layer tends to peel off when the belt is run, worsening the meshing and reducing durability. In contrast, by laminating the resin film layer 2c to the inner surface of the fluororesin-containing rubber layer 2b, it is possible to improve smoothness and adhesion to the belt.

[0045] Thus, while laminating the inner surface of the tooth cloth 2a with either a fluororesin-containing rubber layer 2b or a resin film layer 2c alone yields little effect, the present invention significantly improves jumping resistance and durability by combining both layers.

[0046] In the embodiment shown in Figure 1, the laminate 2 that constitutes the surface of the tooth portion is a constituent element of the tooth portion, while the laminate 2 that constitutes the surface of the tooth root portion is a constituent element of the back portion. Furthermore, each laminate 2 that constitutes the tooth portion is a part of a continuous laminate 2 (a part of the laminate 2 in Figure 2).

[0047] In this example, the tooth portion 1a has a substantially trapezoidal cross-sectional shape in the circumferential direction of the belt. Furthermore, the circumferential surface of the tooth portion 1a, which has a substantially trapezoidal cross-section, is formed of the laminate 2, and the interior is formed of a tooth rubber layer 3 interposed between the laminate 2 and the core wire 4.

[0048] Furthermore, in the tooth root portion 1b, a tooth rubber layer 3 is interposed between the laminate 2 and the core wire 4 (not shown). The thickness of the tooth rubber layer 3 in the tooth root portion 1b is extremely thin compared to the thickness of the tooth rubber layer 3 in the tooth portion 1a.

[0049] The core wires 4 extend in the longitudinal direction (circumferential direction) of the belt and are arranged at intervals in the width direction of the belt. The gaps between adjacent core wires 4 may be formed by the cross-linked rubber composition that constitutes the back rubber layer 5 and / or the tooth rubber layer 3 (in particular, the cross-linked rubber composition that constitutes the back rubber layer 5).

[0050] Toothed belts are used in high-load power transmission applications such as industrial machinery, internal combustion engines in automobiles, and rear-wheel drives in motorcycles. For example, when a toothed belt is wrapped between a drive pulley (toothed pulley) and a driven pulley (toothed pulley), power is transmitted from the drive pulley to the driven pulley as the drive pulley rotates.

[0051] The toothed belt of the present invention is not limited to the forms and structures shown in Figures 1 to 3. For example, the tooth rubber layer is not limited to the single-layer tooth rubber layer shown in Figure 1, but may be a laminated structure of two or more layers, and a two-layer tooth rubber layer is preferred.

[0052] Figure 5 shows a schematic cross-sectional view of a toothed belt with a two-layer tooth rubber layer. In this example, it is identical to the toothed belt shown in Figure 1, except that the tooth rubber layer is formed in a two-layer structure consisting of a first rubber layer on the inner circumference of the belt and a second rubber layer on the outer circumference of the belt.

[0053] In other words, in this example, the tooth rubber layer is formed of a first rubber layer (surface rubber layer) 3a formed along the tooth fabric 2a and a second rubber layer (internal rubber layer) 3b formed between the first rubber layer 3a and the core wire 4, and the elastic modulus of the first rubber layer 3a is adjusted to be greater than that of the second rubber layer 3b. Specifically, the first rubber layer 3a is arranged on the inner circumferential surface side of the belt along the contour of the tooth fabric 2a and is a layer formed along the tooth fabric 2a (in contact with the tooth fabric 2a). On the other hand, the second rubber layer 3b is arranged on the outer circumferential surface side of the belt of the first rubber layer 3a and is a layer formed between the first rubber layer 3a and the core wire 4 (in contact with the core wire 4).

[0054] Furthermore, in the tooth root portion 1b, a first rubber layer acting as a surface rubber layer and a second rubber layer acting as an internal rubber layer are interposed between the tooth fabric 2a and the core wire 4 (not shown). The thickness of the first and second rubber layers in the tooth root portion is extremely thin compared to the thickness of the first rubber layer 3a and the second rubber layer 3b in the tooth portion 1a.

[0055] Furthermore, the multiple teeth only need to be able to mesh with the toothed pulley, and the cross-sectional shape of the teeth (the cross-sectional shape of the toothed belt in the circumferential direction) is not limited to a substantially trapezoidal shape, but may be, for example, semicircular, semielliptical, polygonal [triangle, quadrilateral (rectangle, trapezoid, etc.)], etc. Of these, a trapezoidal or substantially trapezoidal shape is preferred from the viewpoint of meshing and power transmission.

[0056] In the toothed belt of the present invention, the average distance between the centers of adjacent teeth in the circumferential direction (tooth pitch, see Figure 2) may be, for example, 2 to 25 mm, depending on the shape of the toothed pulley. The tooth pitch value corresponds to the size of the tooth scale (length of the tooth in the belt circumferential direction, and tooth height). That is, the larger the tooth pitch, the larger the tooth scale becomes. In particular, in applications where high loads are applied, teeth with a large scale are required, and the tooth pitch may be 5 mm or more, preferably 8 mm or more, more preferably 9 mm or more, even more preferably 11 mm or more, and most preferably 14 mm or more, from the viewpoint of improving jumping resistance and durability.

[0057] Furthermore, the average tooth height of the teeth is, for example, 40-70%, preferably 50-65%, of the average value of the total belt thickness [thickness (distance or height) from the back surface (outer surface) to the tooth crown].

[0058] In this application, as shown in Figure 2, the average tooth height of the teeth refers to the average height of the protruding teeth on the inner circumferential surface of the belt [the average value of the thickness (distance or height) from the tooth root surface to the tooth apex].

[0059] [Tooth portion] The tooth portion includes a laminate arranged on the surface side (inner surface side) and a tooth rubber layer (rubber layer forming the tooth portion) arranged or interposed between the laminate and the core wire. The laminate is composed of a tooth cloth laminated on the inner circumferential surface of the tooth rubber layer, a fluororesin-containing rubber layer laminated on the inner circumferential surface of the tooth cloth, and a resin film layer laminated on the inner circumferential surface of the fluororesin-containing rubber layer.

[0060] (Tooth Rubber Layer) The tooth rubber layer may be formed from a crosslinked rubber composition that is conventionally used as the rubber composition for toothed belts. The tooth rubber layer may be a tooth rubber layer formed from a single phase of the crosslinked rubber composition (a single-layer rubber layer), or it may be a tooth rubber layer in which different phases formed from multiple types of crosslinked rubber compositions are mixed. Examples of such tooth rubber layers include a single-layer tooth rubber layer and a tooth rubber layer having a laminated structure of two or more layers. Of these, from the viewpoint of productivity, the single-layer tooth rubber layer shown in Figure 1 and the two-layer tooth rubber layer shown in Figure 5 (a tooth rubber layer formed from a first rubber layer on the inner circumference side of the belt and a second rubber layer on the outer circumference side of the belt) are preferred, and the two-layer tooth rubber layer is particularly preferred.

[0061] (Two-layer tooth rubber layer) The two-layer tooth rubber layer has a first rubber layer formed on the inner circumference side of the belt along the tooth fabric, and a second rubber layer formed on the outer circumference side of the belt in contact with the first rubber layer, and the modulus of the first rubber layer is adjusted to be greater than that of the second rubber layer.

[0062] By adopting such a two-layer structure for the tooth rubber layer, the low rigidity of the inside of the tooth (the second rubber layer on the outer circumference of the belt) ensures flexibility (bendability), while the high rigidity near the tooth fabric improves the deformation resistance of the tooth and thus improves jumping resistance. Furthermore, in relation to the resin film layer, while large deformation of the tooth makes the resin film layer prone to peeling, the two-layer structure increases the deformation resistance of the tooth and suppresses the peeling of the resin film layer.

[0063] The shape of the first rubber layer is not particularly limited as long as it is layered along the tooth fabric, and is not limited to the layered shape with uneven thickness shown in Figure 5 (i.e., in a cross-sectional view of the tooth portion in the longitudinal direction of the belt, the thickness of the layer is maximum at the top or middle of the tooth portion and decreases toward the bottom of the tooth portion), but may also be a layered shape with uniform thickness. Of these, a layered shape with uneven thickness (particularly, in a cross-sectional view of the tooth portion in the longitudinal direction of the belt, the thickness of the layer is maximum at the top or middle of the tooth portion and decreases toward the bottom of the tooth portion) is preferred from the viewpoint of productivity, etc.

[0064] In the teeth, the area ratio of the first rubber layer can be selected from a range of approximately 5 to 85 area percent of the total area of ​​the first and second rubber layers in a cross-sectional view in the longitudinal direction (circumferential direction) of the belt, for example, 10 to 80 area percent, preferably 20 to 70 area percent, more preferably 30 to 60 area percent, and more preferably 35 to 50 area percent. If this area ratio is too small, the rigidity (deformation resistance) of the teeth may be insufficient, and conversely, if it is too large, the bending rigidity of the belt will be high, the flexibility (flexibility) will be insufficient, and the durability of the belt may decrease. In applications where belt durability is important, the area ratio is preferably 15 to 65 area percent, and more preferably 20 to 60 area percent.

[0065] The shape of the second rubber layer is not limited to a substantially trapezoidal shape formed between the first rubber layer and the core wire in a cross-sectional view in the longitudinal direction of the belt of the teeth, but may be a layered shape formed along the first rubber layer, or a substantially trapezoidal shape formed between another rubber layer formed along the first rubber layer and the core wire. Of these, a shape that is in contact with the core wire, i.e., a substantially trapezoidal shape formed between the first rubber layer and the core wire, or a substantially trapezoidal shape formed between the other rubber layer and the core wire is preferred from the viewpoint of improving the flexibility of the belt, and a substantially trapezoidal shape formed between the first rubber layer and the core wire is particularly preferred.

[0066] The rubber hardness of the first rubber layer (the first crosslinked rubber composition constituting the first rubber layer) is, for example, 65 to 80, preferably 68 to 78, more preferably 70 to 76, and most preferably 72 to 74, on a Type D hardness scale. If the hardness is too low, the rigidity of the teeth may decrease, reducing deformation resistance. Conversely, if it is too high, the flexibility of the belt, particularly its ability to wrap around (engage with) small-diameter pulleys, may decrease.

[0067] The rubber hardness of the second rubber layer (the second crosslinked rubber composition constituting the second rubber layer) is, for example, 50 to 66, preferably 53 to 65, more preferably 54 to 62, even more preferably 55 to 60, and most preferably 56 to 59 on a Type D hardness scale. If the hardness is too low, the deformation resistance may decrease, and conversely, if it is too high, the durability of the belt against bending may decrease.

[0068] In this application, the Type D or Type A hardness of each rubber layer refers to the value (Type D or Type A) measured using a Type D or Type A durometer in accordance with the spring durometer hardness test specified in JIS K 6253 (2012) (Vulcanized rubber and thermoplastic rubber - Method for determining hardness), and may simply be referred to as rubber hardness. In detail, it can be measured by the method described in the examples below, and can be measured as the hardness of a rubber sheet obtained by crosslinking a rubber composition for forming a belt.

[0069] Typically, the rubber hardness of rubber compositions is measured using Type A hardness (a value measured using a Type A durometer). However, if the value measured using a Type A durometer exceeds 90, it is considered preferable to use a Type D durometer.

[0070] (First Crosslinked Rubber Composition) The first rubber layer is formed of a first crosslinked rubber composition containing a first rubber component, and may be formed of a crosslinked rubber composition that is conventionally used as a rubber composition for toothed belts. The first crosslinked rubber composition may be a first crosslinked rubber composition containing a first rubber component, and the mechanical properties of the first rubber layer, such as the modulus, can be adjusted by appropriately adjusting the composition of the composition. The method for adjusting the modulus, etc., is not particularly limited, and may be adjusted by changing the composition and / or type of components constituting the composition, and from the viewpoint of simplicity, it is preferable to adjust by changing the ratio and / or type of crosslinking compounding agent, short fibers, and filler.

[0071] (1A) First rubber component Examples of the rubber component (first rubber component) of the first crosslinked rubber composition that forms the first rubber layer include diene rubber [natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), butyl rubber (IIR), styrene-butadiene rubber (SBR), vinylpyridine-styrene-butadiene rubber, acrylonitrile-butadiene rubber (nitrile rubber: NBR), acrylonitrile-chloroprene rubber, hydrogenated nitrile rubber (HNBR), etc.], ethylene-α-olefin elastomer (ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.), chlorosulfonated polyethylene rubber (CSM), alkylated chlorosulfonated polyethylene rubber (ACSM), epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluororubber, etc. These rubber components may be carboxylated, such as carboxylated SBR or carboxylated NBR. These rubber components can be used individually or in combination of two or more.

[0072] A particularly preferred first rubber component is hydrogenated nitrile rubber (HNBR), and chloroprene rubber (CR) and ethylene-propylene-diene terpolymer (EPDM) are also suitably used. A particularly preferred rubber component for applications subjected to high loads is a rubber with high heat aging resistance, in particular hydrogenated nitrile rubber (HNBR) which may be carboxylated (hereinafter, including carboxylated hydrogenated nitrile rubber, it may simply be referred to as hydrogenated nitrile rubber). The proportion of the above preferred rubber component in the rubber component is preferably 50% by mass or more (for example, about 80 to 100% by mass), and particularly preferably 100% by mass. The hydrogenated nitrile rubber which may be carboxylated may be partially hydrogenated nitrile rubber or fully hydrogenated nitrile rubber. The hydrogenation rate of the hydrogenated nitrile rubber which may be carboxylated can be selected from a range of about 50 to 100%, and may be 70 to 100%.

[0073] In this application, HNBR refers to a type of rubber that maintains the oil resistance advantage of conventional nitrile rubber while preventing the deterioration of rubber elasticity due to sulfur recombination reactions during thermal aging. This is achieved by chemically hydrogenating the unsaturated bonds (carbon-carbon double bonds) present in conventional nitrile rubber, thereby making recombination reactions during thermal aging less likely to occur and improving heat resistance.

[0074] The iodine value (unit: mg / 100 mg) of HNBR is, for example, 5 to 60, preferably 7 to 50, more preferably 8 to 40, even more preferably 8 to 35, and most preferably 10 to 30.

[0075] In this application, the iodine value is an indicator of the amount of unsaturated bonds; a higher iodine value indicates a greater amount of unsaturated bonds in the polymer molecular chain. The iodine value is determined by adding an excess of iodine to the sample and allowing it to react completely (reacting with unsaturated bonds), then quantifying the remaining amount of iodine by redox titration. If the iodine value of HNBR is low, the crosslinking reaction between HNBRs is insufficient, resulting in lower rigidity of the crosslinked rubber, which may reduce deformation resistance during belt operation. On the other hand, if the iodine value of HNBR is high, the amount of unsaturated bonds becomes excessively high, which may lead to thermal and oxidative degradation of the crosslinked rubber, shortening the belt life.

[0076] The first rubber component preferably contains at least hydrogenated nitrile rubber, which may be carboxylated. The proportion of such hydrogenated nitrile rubber may be 80 to 100% by mass of the rubber component, preferably 90 to 100% by mass, and more preferably 100% by mass.

[0077] The first rubber component preferably contains a composite polymer (hereinafter referred to as "HNBR / unsaturated carboxylate metal salt composite polymer") comprising hydrogenated nitrile rubber and an unsaturated carboxylate metal salt. This composite polymer may also be a polymer alloy. This polymer can increase the modulus and hardness of the tooth portion.

[0078] An unsaturated carboxylate metal salt may be a compound in which an unsaturated carboxylic acid having one or more carboxyl groups is ionically bonded to a metal.

[0079] Examples of unsaturated carboxylic acids in metal salts of unsaturated carboxylic acids include monocarboxylic acids such as (meth)acrylic acid and crotonic acid, dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, and monoalkyl esters of these dicarboxylic acids. These unsaturated carboxylic acids can be used alone or in combination of two or more. A preferred unsaturated carboxylic acid is (meth)acrylic acid.

[0080] Examples of metals used in unsaturated carboxylate metal salts include polyvalent metals, such as Group 2 elements of the periodic table (magnesium, calcium, etc.), Group 4 elements (titanium, zirconium, etc.), and Groups 8 to 14 elements of the periodic table (e.g., iron, cobalt, nickel, copper, zinc, aluminum, tin, lead, etc.). These metals can be used individually or in combination of two or more. Preferred metals include Group 2 elements of the periodic table (magnesium, etc.) and Group 12 elements of the periodic table (zinc, etc.).

[0081] Examples of preferred unsaturated carboxylate metal salts include zinc (meth)acrylate and magnesium (meth)acrylate. Unsaturated carboxylate metal salts can be used individually or in combination of two or more.

[0082] Furthermore, commercially available HNBR / unsaturated carboxylate metal salt composite polymers may be used. For example, a product in which zinc methacrylate is highly finely dispersed as an unsaturated carboxylate metal salt in HNBR can be used (e.g., Zeon Corporation's product name "Zeoforte (ZSC)").

[0083] Furthermore, the HNBR / unsaturated carboxylate metal salt composite polymer may be a mixture of a composite polymer in which an unsaturated carboxylate metal salt is finely dispersed in HNBR and hydrogenated nitrile rubber (HNBR) that does not contain an unsaturated carboxylate metal salt. That is, in the HNBR / unsaturated carboxylate metal salt composite polymer, the mass ratio of hydrogenated nitrile rubber to unsaturated carboxylate metal salt may be adjusted by mixing commercially available HNBR containing an unsaturated carboxylate metal salt with commercially available hydrogenated nitrile rubber. The modulus and hardness of the first crosslinked rubber composition may be adjusted by changing the mixing ratio of the two.

[0084] In HNBR / unsaturated carboxylic acid metal salt composite polymers, the mass ratio of hydrogenated nitrile rubber to unsaturated carboxylic acid metal salt can be selected from a range of approximately 100 / 70 to 100 / 180, for example, 100 / 90 to 100 / 170, preferably 100 / 95 to 100 / 150, and more preferably 100 / 100 to 100 / 120. If the proportion of unsaturated carboxylic acid metal salt is too low, the modulus and hardness of the crosslinked rubber composition (or teeth) may decrease, while if it is too high, the processability and flexibility of the belt may decrease.

[0085] The proportion of the HNBR / unsaturated carboxylate metal salt composite polymer may be 10% by mass or more in the first rubber component, preferably 30% by mass or more, more preferably 50% by mass or more, more preferably 80% by mass or more, most preferably 90% by mass or more, and may also be 100% by mass. These proportions may be those used in the product "Zeoforte (ZSC)".

[0086] As other rubber components to be combined with the HNBR / unsaturated carboxylic acid metal salt composite polymer, at least one selected from the group consisting of EPDM and CR is preferred. The proportion of the other rubber components is, for example, 70% by mass or less, preferably 50% by mass or less, more preferably 30% by mass or less, and most preferably 10% by mass or less, in the first rubber component.

[0087] The proportion of the first rubber component may be 10 to 90% by mass in the first crosslinked rubber composition, preferably 20 to 80% by mass, more preferably 30 to 75% by mass, more preferably 50 to 70% by mass, and most preferably 55 to 65% by mass.

[0088] (1B) First Filling Compound The first crosslinked rubber composition may further contain a first filling compound. Examples of the first filling compound include a first filler and a first short fiber.

[0089] The first filler may be a first reinforcing filler or a first non-reinforcing filler.

[0090] Examples of the first reinforcing filler include carbon black and silica.

[0091] Examples of the first non-reinforcing fillers include polyvalent metal carbonates (calcium carbonate, magnesium carbonate, etc.), polyvalent metal hydroxides (aluminum hydroxide, etc.), polyvalent metal sulfates (barium sulfate, etc.), silicates (natural or synthetic silicates in which some of the silicon is replaced by polyvalent metal atoms, such as aluminum silicate, magnesium silicate, and aluminum magnesium silicate; minerals mainly composed of silicates, such as clay containing aluminum silicate, and silicate minerals such as talc and mica containing magnesium silicate), lithopone, silica sand, and other non-reinforcing fillers.

[0092] These fillers can be used individually or in combination of two or more. It is preferable that these fillers include a reinforcing filler, and a combination of a reinforcing filler and a non-reinforcing filler is particularly preferred.

[0093] The first reinforcing filler preferably contains carbon black, and carbon black alone is particularly preferred.

[0094] The average particle size (average primary particle size) of the carbon black is, for example, 5 to 200 nm, preferably 10 to 150 nm, more preferably 20 to 100 nm, more preferably 30 to 80 nm, and most preferably 40 to 70 nm.

[0095] In this application, the average primary particle size of carbon black can be measured using a transmission electron microscope at the arithmetic mean particle size of an appropriate number of samples (e.g., 50 samples).

[0096] The amount of iodine adsorbed by carbon black is, for example, 5 to 200 mg / g, preferably 10 to 150 mg / g, more preferably 15 to 100 mg / g, and more preferably 20 to 80 mg / g.

[0097] The proportion of the first reinforcing filler may be, for example, 100 parts by mass or less per 100 parts by mass of the first rubber component, preferably 50 parts by mass or less, more preferably 30 parts by mass or less, more preferably 10 parts by mass or less, and most preferably 5 parts by mass or less (for example, 1 to 5 parts by mass). If the proportion of the first reinforcing filler is too high, the dispersibility of the first reinforcing filler may decrease.

[0098] The first non-reinforcing filler preferably includes at least one selected from, for example, calcium carbonate, magnesium silicate or talc containing magnesium silicate, aluminum silicate or clay containing aluminum silicate, and is particularly preferably calcium carbonate. As the first non-reinforcing filler, commercially available powdered fillers used as rubber fillers can be used.

[0099] The average particle size (average primary particle size) of the first non-reinforcing filler can be selected from a range of approximately 0.01 to 25 μm (e.g., 0.2 to 20 μm), preferably 0.5 to 17 μm (e.g., 1 to 15 μm). The average particle diameter (average primary particle diameter) of the first filler may be approximately 0.2 to 5 μm (e.g., 0.3 to 3 μm), preferably 0.5 to 2.5 μm (particularly 1 to 2 μm). Depending on the type of first filler, such as magnesium silicate or its minerals, the first filler may be crushed or broken during the mixing process with rubber components. The average particle size of such a crushable or breakable first filler may be the average particle diameter before mixing with rubber components.

[0100] In this application, the average particle size of the first unreinforced filler can be measured as a volume-average particle size using a laser diffraction particle size distribution analyzer. Furthermore, the average particle diameter of the nanometer-sized first filler can be calculated as the arithmetic mean particle size of an appropriate number of samples (e.g., 50 samples) by image analysis of electron microscope images, including scanning electron microscope images.

[0101] The proportion of the first non-reinforcing filler is, for example, 70 parts by mass or less, preferably 50 parts by mass or less, more preferably 40 parts by mass or less (for example, 1 to 40 parts by mass), and more preferably 30 parts by mass or less (for example, 10 to 30 parts by mass), per 100 parts by mass of the first rubber component. If the proportion of the first non-reinforcing filler is too high, the dispersibility of the filler may decrease.

[0102] The first short fibers may be oriented (arranged) in a predetermined direction during the process of preparing an uncrosslinked rubber sheet by rolling a rubber composition kneaded in a Banbury mixer or the like using a roll or calender. In the tooth rubber layer constituting the teeth, it is preferable to arrange the orientation direction of the first short fibers toward the belt circumferential direction. Furthermore, it is preferable that the first short fibers are oriented along the contour of the teeth on the side closer to the tooth fabric, and as they approach the core wire, the first short fibers are oriented so as to become approximately parallel to the core wire.

[0103] In this application, the state in which the first short fibers are oriented along the contour of the tooth means not only the state in which the first short fibers are oriented substantially parallel to the contour of the tooth, but also the state in which the first short fibers are oriented substantially parallel to the contour of the tooth fabric (or inner surface). The same applies to the state in which the first short fibers are oriented in the longitudinal direction of the belt.

[0104] Furthermore, in this application, the "tooth contour" may be the contour of the first rubber layer, or if the tooth includes a tooth cloth, it may be the tooth cloth surface or the interface between the tooth cloth and the first rubber layer, or it may be the interface between the first rubber layer and the second rubber layer. In particular, whether or not the first short fibers are oriented along the contour of the tooth may be determined based on the interface between the first rubber layer and the second rubber layer. For example, if the first short fibers are substantially parallel to the corresponding interface (the corresponding part of the interface at the shortest distance from the first short fibers), it may be determined that they are oriented along the contour of the tooth.

[0105] Examples of the first short fibers include polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), polyamide fibers [aliphatic polyamide fibers such as polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers (nylon fibers), aramid fibers, etc.], polyester fibers [polyalkylene arylate fibers (for example, polyethylene terephthalate (PET) fibers, polytrimethylene terephthalate (PTT) fibers, polybutylene terephthalate (PBT) fibers, polyethylene naphthalate (PEN) fibers, etc.)], ２－４ Alkilen C ８－１４ Examples of synthetic fibers include: arylate fibers; polyarylate fibers, fully aromatic polyester fibers such as liquid crystal polyester fibers, etc.; vinylon fibers, polyvinyl alcohol fibers, poly-p-phenylenebenzobisoxazole (PBO) fibers; natural fibers such as cotton, linen, and wool; regenerated cellulose fibers such as rayon; cellulose ester fibers, etc.; and inorganic fibers such as carbon fibers and glass fibers. These short fibers can be used individually or in combination of two or more types. In particular, fibers with high modulus, such as polyamide fibers, PBO fibers, glass fibers, and carbon fibers, can be suitably used, with polyamide fibers such as aliphatic polyamide fibers (nylon fibers) and aramid fibers, and PBO fibers being more preferable, and aliphatic polyamide fibers being the most preferable.

[0106] The average fiber diameter of the first short fibers is, for example, 1 to 100 μm, preferably 3 to 70 μm, more preferably 5 to 50 μm, and more preferably 10 to 30 μm. The average fiber length of the first short fibers is, for example, 0.3 to 10 mm, preferably 0.5 to 7 mm, more preferably 1 to 5 mm, and more preferably 2 to 4 mm. If the average fiber diameter of the first short fibers is too small or the average fiber length is too long, there is a risk that the first short fibers will not be able to be dispersed uniformly, and if the average fiber diameter is too large or the average fiber length is too short, there is a risk that the strength of each rubber layer will decrease.

[0107] The proportion of the first short fibers may be 60 parts by mass or less per 100 parts by mass of the first rubber component, and can be selected from a range of about 0 to 50 parts by mass depending on the application. The proportion of the first short fibers can be selected depending on the application, for example, in applications where high load (high horsepower) is required, it may be, for example, 5 to 60 parts by mass, preferably 10 to 55 parts by mass, more preferably 15 to 45 parts by mass, more preferably 20 to 40 parts by mass, and most preferably 25 to 35 parts by mass per 100 parts by mass of the first rubber component. In addition, in applications where low load is required, the proportion of the first short fibers may be 10 parts by mass or less, preferably 7 parts by mass or less, and more preferably 5 parts by mass or less per 100 parts by mass of the first rubber component.

[0108] Furthermore, it is preferable to subject the first short fibers to a conventional adhesive treatment (or surface treatment) to adhere an adhesive component to at least a portion of the surface of the short fibers. Examples of adhesive treatments include treatment with adhesive components such as epoxy compounds (or epoxy resins), polyisocyanates, silane coupling agents, and RFL liquid.

[0109] The proportion of the first filling compound is, for example, 10 to 100 parts by mass, preferably 20 to 80 parts by mass, more preferably 30 to 70 parts by mass, and more preferably 40 to 60 parts by mass, per 100 parts by mass of the first rubber component.

[0110] (1C) First Crosslinking Compound The first crosslinked rubber composition may further contain a first crosslinking compound. Examples of the first crosslinking compound include a first crosslinking agent (vulcanizing agent) for crosslinking the first rubber component, as well as a first co-crosslinking agent, a first crosslinking accelerator (vulcanization accelerator), a first crosslinking retarder (vulcanization retarder), and the like. Of these, the first crosslinking compound preferably contains at least a first crosslinking agent and a first co-crosslinking agent, and a combination of a first crosslinking agent and a first co-crosslinking agent is particularly preferred.

[0111] As the first crosslinking agent, conventional components can be used depending on the type of first rubber component, and examples include organic peroxides, sulfur-based crosslinking agents, and metal oxides.

[0112] Examples of organic peroxides include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 1,1-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis(t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyn-3, 1,3-bis(t-butylperoxy-di-isopropyl)benzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxybenzoate, and t-butylperoxy-2-ethyl-hexyl carbonate. These organic peroxides can be used individually or in combination of two or more.

[0113] Examples of sulfur-based crosslinking agents include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and sulfur chloride (sulfur monochloride, sulfur dichloride, etc.). These sulfur-based crosslinking agents can be used individually or in combination of two or more.

[0114] Examples of metal oxides include magnesium oxide, zinc oxide, and lead oxide. These metal oxides can be used individually or in combination of two or more.

[0115] The first crosslinking agent can be appropriately selected depending on the type of the first rubber component, and organic peroxides and metal oxides are preferred, with organic peroxides being particularly preferred. The first crosslinking agent may also be a combination of organic peroxides and metal oxides.

[0116] The proportion of the first crosslinking agent is, for example, 1 to 20 parts by mass, preferably 3 to 15 parts by mass, and more preferably 5 to 10 parts by mass, per 100 parts by mass of the first rubber component. If the proportion of the first crosslinking agent is too low, the modulus and hardness of the first crosslinked rubber composition will decrease, while if it is too high, the flexibility of the belt will decrease.

[0117] The proportion of the organic peroxide can be selected from a range of about 0.5 to 20 parts by mass per 100 parts by mass of the first rubber component, for example, 0.5 to 10 parts by mass, preferably 0.7 to 5 parts by mass, more preferably 0.8 to 4 parts by mass, and more preferably 1 to 3 parts by mass.

[0118] The proportion of the metal oxide is, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, and most preferably 3 to 7 parts by mass, per 100 parts by mass of the first rubber component.

[0119] The first co-crosslinking agent (crosslinking aid or co-vulcanizing agent) is a known crosslinking aid, for example, polyfunctional (iso)cyanurates [e.g., triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), etc.], polydienes (e.g., 1,2-polybutadiene, etc.), metal salts of unsaturated carboxylic acids [e.g., polyvalent metal salts of (meth)acrylic acids such as zinc (meth)acrylate and magnesium (meth)acrylate], oximes (e.g., quinone dioxime, etc.), guanidines (e.g., diphenylguanidine, etc.), polyfunctional (meth)acrylates [e.g., ethylene glycol di(meth)acrylate, alkanediol di(meth)acrylate such as butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol ester Examples include alkane polyol poly(meth)acrylates such as tra(meth)acrylate, and bismaleimides (aliphatic bismaleimides, e.g., alkylene bismaleimides such as N,N'-1,2-ethylenedimaleimide, N,N'-hexamethylenebismaleimide, 1,6'-bismaleimide-(2,2,4-trimethyl)cyclohexane; arene bismaleimides or aromatic bismaleimides, e.g., N,N'-m-phenylenedimaleimide, 4-methyl-1,3-phenylenedimaleimide, 4,4'-diphenylmethanedimaleimide, 2,2-bis[4-(4-maleimoidphenoxy)phenyl]propane, 4,4'-diphenyletherdimaleimide, 4,4'-diphenylsulfonedimaleimide, 1,3-bis(3-maleimoidphenoxy)benzene, etc.). These cocrosslinking agents can be used alone or in combination of two or more. Among these cocrosslinking agents, polyfunctional (iso)cyanurates, polyfunctional (meth)acrylates, and bismaleimides (arene bismaleimides such as N,N'-m-phenylenedimaleimide or aromatic bismaleimides) are preferred, with bismaleimides being particularly preferred. The degree of crosslinking and the elastic modulus can be improved by adding a cocrosslinking agent (e.g., bismaleimides).

[0120] The proportion of the first co-crosslinking agent (crosslinking aid), such as bismaleimides, can be selected from a range of 40 parts by mass or less (for example, 0.2 to 40 parts by mass) per 100 parts by mass of the first rubber component, for example, 0.3 to 30 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 0.8 to 15 parts by mass, and more preferably 1 to 10 parts by mass. In applications requiring high load (high horsepower), the proportion of the first co-crosslinking agent may be, for example, 1 to 40 parts by mass, preferably 2 to 30 parts by mass (for example, 5 to 20 parts by mass), more preferably 2.5 to 18 parts by mass (for example, 8 to 15 parts by mass), more preferably 3 to 14 parts by mass (for example, 4 to 12 parts by mass), and most preferably 6 to 11 parts by mass (for example, 5 to 7 parts by mass) per 100 parts by mass of the first rubber component.

[0121] The proportion of the first crosslinking compound can be selected from a range of about 1 to 50 parts by mass per 100 parts by mass of the first rubber component, for example, 2 to 30 parts by mass, preferably 3 to 25 parts by mass, more preferably 5 to 20 parts by mass, and more preferably 7 to 15 parts by mass.

[0122] (1D) First Other Compounding Agent The first crosslinked rubber composition may further contain conventional additives used in rubber compositions for toothed belts. Commonly used additives include, for example, metal oxides (calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), softeners (oils such as paraffin oil and naphthenic oils), processing agents or processing aids (stearic acid or its metal salts, waxes, paraffin, fatty acid amides, etc.), plasticizers [aliphatic carboxylic acid plasticizers (adipate ester plasticizers, sebacate ester plasticizers, etc.), aromatic carboxylic acid ester plasticizers (phthalate ester plasticizers, trimellitic acid ester plasticizers, etc.), oxycarboxylic acid ester plasticizers, phosphate ester plasticizers, ether plasticizers, ether ester plasticizers, etc.], antioxidants (antioxidants, heat aging inhibitors, flex crack inhibitors, ozone degradation inhibitors, etc.), colorants, adhesion improvers, tackifiers, plasticizers, coupling agents (silane coupling agents, etc.), stabilizers (ultraviolet absorbers, heat stabilizers, etc.), flame retardants, and antistatic agents. These additives can be used individually or in combination of two or more.

[0123] In particular, the proportion of the processing agent or processing aid is, for example, 0.1 to 5 parts by mass, preferably 0.2 to 3 parts by mass, and more preferably 0.3 to 1 part by mass, per 100 parts by mass of the first rubber component.

[0124] The proportion of the anti-aging agent is, for example, 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, and more preferably 1 to 3 parts by mass, per 100 parts by mass of the first rubber component.

[0125] The total proportion of the first other compounding agent is, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the first rubber component.

[0126] (Second Crosslinked Rubber Composition) The second rubber layer is formed of a second crosslinked rubber composition containing a second rubber component, and may be formed of a crosslinked rubber composition that is conventionally used as a rubber composition for toothed belts. The second crosslinked rubber composition is a crosslinked rubber composition with a different composition from the first crosslinked rubber composition. That is, the first rubber layer is a single-phase layer formed of the first crosslinked rubber composition, and the second rubber layer is a single-phase layer formed of the second crosslinked rubber composition.

[0127] The second crosslinked rubber composition may be a second crosslinked rubber composition containing a second rubber component, and the mechanical properties such as the modulus of the second rubber layer can be adjusted by appropriately adjusting the composition of the composition. The method for adjusting the modulus of elasticity, etc., is not particularly limited, and it may be adjusted by changing the composition and / or type of the components constituting the composition, but from the viewpoint of simplicity, it is preferable to adjust by changing the proportion and / or type of crosslinking compounding agent, short fibers, and filler.

[0128] (2A) Second rubber component The second rubber component of the second crosslinked rubber composition that forms the second rubber layer can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The second rubber component is preferably of the same series or type as the first rubber component, and more preferably of the same type, in order to improve interlayer adhesion.

[0129] In the second rubber component, in the HNBR / unsaturated carboxylic acid metal salt composite polymer, the mass ratio of hydrogenated nitrile rubber to unsaturated carboxylic acid metal salt is former / latter = 100 / 70 to 100 / 110, preferably 100 / 75 to 100 / 100, and more preferably 100 / 80 to 100 / 90. If the proportion of unsaturated carboxylic acid metal salt is too low, the modulus and hardness of the crosslinked rubber composition (or teeth) may decrease, while if it is too high, the processability and flexibility of the belt will decrease.

[0130] The proportion of the second rubber component may be 10 to 95% by mass in the second crosslinked rubber composition, preferably 30 to 93% by mass, more preferably 50 to 90% by mass, more preferably 60 to 85% by mass, and most preferably 70 to 80% by mass.

[0131] (2B) Second Filling Compound The second crosslinked rubber composition may further contain a second filling compound. Examples of the second filling compound include a second filler and a second short fiber.

[0132] The second filler may be a second reinforcing filler or a second non-reinforcing filler.

[0133] The second reinforcing filler can be selected from the fillers exemplified as the first reinforcing filler, including preferred embodiments.

[0134] The range of average particle size and iodine adsorption amount of carbon black in the second reinforcing filler can be selected from the range described for the average particle size and iodine adsorption amount of carbon black in the first reinforcing filler, including preferred ranges.

[0135] The range of the ratio of the second reinforcing filler to the second rubber component can be selected from the range described as the ratio of the first reinforcing filler to the first rubber component, including a preferred range.

[0136] The second non-reinforcing filler can be selected from the fillers exemplified as the first non-reinforcing filler, including preferred embodiments.

[0137] The range of the average particle size of the second non-reinforcing filler and its ratio to the second rubber component can be selected from the range described as the average particle size of the first non-reinforcing filler and its ratio to the first rubber component, including preferred ranges.

[0138] The second short fiber can be selected from the short fibers exemplified as the first short fiber. The short fibers can be used alone or in combination of two or more types. Among the short fibers, the second short fiber can preferably be a polyamide fiber, PBO fiber, glass fiber, carbon fiber, or other fiber with a high modulus of elasticity. Polyamide fibers such as aliphatic polyamide fibers (nylon fibers) and aramid fibers, and PBO fibers are more preferred, with aramid fibers being the most preferred.

[0139] The proportion of the second short fibers may be 50 parts by mass or less per 100 parts by mass of the second rubber component, for example, 0.1 to 50 parts by mass, preferably 0.2 to 30 parts by mass, more preferably 0.3 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and most preferably 1 to 3 parts by mass.

[0140] The second short fiber may also be subjected to conventional bonding treatment, similar to the first short fiber.

[0141] The proportion of the second filling compound is, for example, 5 to 100 parts by mass, preferably 10 to 50 parts by mass, more preferably 15 to 40 parts by mass, and more preferably 20 to 30 parts by mass, per 100 parts by mass of the second rubber component.

[0142] (2C) Second Crosslinking Compound The second crosslinked rubber composition may further contain a second crosslinking compound. Examples of the second crosslinking compound include a second crosslinking agent (vulcanizing agent) for crosslinking the second rubber component, as well as a second cocrosslinking agent, a second crosslinking accelerator (vulcanization accelerator), a second crosslinking retarder (vulcanization retarder), and the like. Of these, the second crosslinking compound preferably contains at least a second crosslinking agent and a second cocrosslinking agent, and a combination of a second crosslinking agent and a second cocrosslinking agent is particularly preferred.

[0143] The second crosslinking agent can be selected from the crosslinking agents exemplified as the first crosslinking agent, including preferred embodiments. The range of the ratio of the second crosslinking agent to the second rubber component can be selected from the range described as the ratio of the first crosslinking agent to the first rubber component, including preferred ranges.

[0144] The second co-crosslinking agent can be selected from the co-crosslinking agents exemplified as the first co-crosslinking agent, including preferred embodiments.

[0145] The proportion of the second co-crosslinking agent may be 25 parts by mass or less per 100 parts by mass of the second rubber component, for example, 0.2 to 25 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 0.7 to 5 parts by mass, more preferably 0.8 to 3 parts by mass, and most preferably 0.8 to 2 parts by mass.

[0146] The proportion of the second crosslinking compound can be selected from a range of about 0.2 to 50 parts by mass per 100 parts by mass of the second rubber component, for example, 0.3 to 30 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass.

[0147] (2D) Second Other Compounding Agent The second crosslinked rubber composition may further contain, as a second other compounding agent, conventional additives used in rubber compositions for toothed belts. The conventional additives can be selected from the additives exemplified as the first other compounding agent.

[0148] In particular, the proportion of the processing agent or processing aid is, for example, 0.1 to 5 parts by mass, preferably 0.2 to 3 parts by mass, and more preferably 0.3 to 1 part by mass, per 100 parts by mass of the second rubber component.

[0149] The total proportion of the second other compounding agent is, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the second rubber component.

[0150] (Single-layer tooth rubber layer) The rubber hardness of the single-layer tooth rubber layer (the third crosslinked rubber composition constituting the tooth rubber layer) is, for example, 50 to 80, preferably 53 to 75, more preferably 55 to 70, more preferably 60 to 65, and most preferably 62 to 64 on a Type D hardness scale. If the hardness is too low, the deformation resistance may decrease, and conversely, if it is too high, the durability of the belt against bending may decrease.

[0151] The single-layer tooth rubber layer is formed of a third crosslinked rubber composition containing a third rubber component, and may be formed of a crosslinked rubber composition that is conventionally used as a rubber composition for toothed belts.

[0152] (3A) Third rubber component The third rubber component of the third crosslinked rubber composition can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments.

[0153] The proportion of the third rubber component may be 10 to 95% by mass in the third crosslinked rubber composition, preferably 30 to 93% by mass, more preferably 50 to 90% by mass, more preferably 70 to 85% by mass, and most preferably 80 to 83% by mass.

[0154] (3B) Third Filling Compound The third crosslinked rubber composition may further contain a third filling compound. Examples of the third filling compound include a third filler and a third short fiber.

[0155] The third filler may be a third reinforcing filler or a third non-reinforcing filler.

[0156] The third reinforcing filler can be selected from the fillers exemplified as the first reinforcing filler, including preferred embodiments.

[0157] The range of average particle size and iodine adsorption amount of carbon black in the third reinforcing filler can be selected from the range described as the average particle size and iodine adsorption amount of carbon black in the first reinforcing filler, including preferred ranges.

[0158] The range of the ratio of the third reinforcing filler to the third rubber component can be selected from the range described as the ratio of the first reinforcing filler to the first rubber component, including a preferred range.

[0159] The third non-reinforcing filler can be selected from the fillers exemplified as the first non-reinforcing filler, including preferred embodiments.

[0160] The range of average particle size of the third non-reinforcing filler can be selected from the range described as the average particle size of the first non-reinforcing filler, including a preferred range.

[0161] The proportion of the third non-reinforcing filler is, for example, 70 parts by mass or less, preferably 50 parts by mass or less, more preferably 30 parts by mass or less, more preferably 20 parts by mass or less (for example, 1 to 20 parts by mass), and most preferably 15 parts by mass or less (for example, 5 to 15 parts by mass), per 100 parts by mass of the third rubber component. If the proportion of the third non-reinforcing filler is too high, the dispersibility of the filler may decrease.

[0162] The third short fiber can be selected from the short fibers exemplified as the second short fiber, including preferred embodiments.

[0163] The proportion of the third short fiber may be 50 parts by mass or less per 100 parts by mass of the third rubber component, for example, 0.1 to 50 parts by mass, preferably 0.2 to 10 parts by mass, more preferably 0.3 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and most preferably 0.7 to 2 parts by mass.

[0164] The third short fiber may also be subjected to conventional bonding treatment, similar to the first short fiber.

[0165] The proportion of the third filling compound is, for example, 3 to 100 parts by mass, preferably 5 to 50 parts by mass, more preferably 8 to 30 parts by mass, and more preferably 10 to 20 parts by mass, per 100 parts by mass of the third rubber component.

[0166] (3C) Third Crosslinking Compound The third crosslinked rubber composition may further contain a third crosslinking compound. Examples of third crosslinking compounds include a third crosslinking agent (vulcanizing agent) for crosslinking the third rubber component, as well as a third co-crosslinking agent, a third crosslinking accelerator (vulcanization accelerator), and a third crosslinking retarder (vulcanization retarder). Of these, the third crosslinking compound preferably contains at least a third crosslinking agent, and may be a combination of a third crosslinking agent and a third co-crosslinking agent.

[0167] The third crosslinking agent can be selected from the crosslinking agents exemplified as the first crosslinking agent, including preferred embodiments. The range of the ratio of the third crosslinking agent to the third rubber component can be selected from the range described as the ratio of the first crosslinking agent to the first rubber component, including preferred ranges.

[0168] The third co-crosslinking agent can be selected from the co-crosslinking agents exemplified as the first co-crosslinking agent, including preferred embodiments.

[0169] The proportion of the third co-crosslinking agent may be 25 parts by mass or less (for example, 0.2 to 25 parts by mass) per 100 parts by mass of the third rubber component, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less.

[0170] The proportion of the third crosslinking compound can be selected from a range of about 0.2 to 50 parts by mass per 100 parts by mass of the third rubber component, for example, 0.3 to 30 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass, and more preferably 2 to 8 parts by mass.

[0171] (3D) Third Other Compounding Agent The third crosslinked rubber composition may further contain, as a third other compounding agent, conventional additives used in rubber compositions for toothed belts. The conventional additives can be selected from the additives exemplified as the first other compounding agent.

[0172] The total proportion of the third other compounding agent is, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the third rubber component.

[0173] (Adhesive rubber layer) In order to improve the adhesion between the tooth rubber layer and the tooth cloth, an adhesive rubber layer may be interposed between the tooth rubber layer and the tooth cloth.

[0174] The rubber hardness of the adhesive rubber layer is, for example, 60 to 90 on a Type A hardness scale, preferably 62 to 85, more preferably 63 to 80, even more preferably 65 to 75, and most preferably 68 to 72. If the hardness is too low, the deformation resistance may decrease, and conversely, if it is too high, the adhesiveness may decrease.

[0175] The thickness of the adhesive rubber layer should be sufficient to improve the adhesion between the tooth cloth and the tooth rubber layer. Specifically, the thickness of the adhesive rubber layer at the top of the tooth is preferably 0.5 mm or less (for example, 0.1 to 0.5 mm), and more preferably 0.3 mm or less. If the adhesive rubber layer is too thick, the rigidity of the tooth may decrease.

[0176] In this application, the average thickness of the adhesive rubber layer can be determined by observing it with a microscope and taking the average value of any 10 points.

[0177] The adhesive rubber layer is formed of a fourth crosslinked rubber composition containing a fourth rubber component, and may be formed of a crosslinked rubber composition that is conventionally used as a rubber composition for toothed belts.

[0178] (4A) The fourth rubber component of the fourth crosslinked rubber composition that forms the fourth rubber layer can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The fourth rubber component is preferably of the same series or type as the rubber component of the tooth rubber layer, and more preferably of the same type, in order to improve interlayer adhesion.

[0179] In the fourth rubber component, in the HNBR / unsaturated carboxylic acid metal salt composite polymer, the mass ratio of hydrogenated nitrile rubber to unsaturated carboxylic acid metal salt is former / latter = 100 / 0 to 100 / 110, preferably 100 / 1 to 100 / 50, more preferably 100 / 2 to 100 / 30, and more preferably 100 / 3 to 100 / 10.

[0180] The proportion of the fourth rubber component may be 10 to 95% by mass in the fourth crosslinked rubber composition, preferably 30 to 93% by mass, more preferably 50 to 90% by mass, more preferably 60 to 85% by mass, and most preferably 70 to 80% by mass.

[0181] (4B) Fourth Adhesion-Improver The fourth crosslinked rubber composition may contain a fourth adhesion-improving agent, as it can improve adhesion to the tooth cloth and tooth rubber layer.

[0182] Examples of the fourth adhesion-improving agent include phenolic resins [such as resorcinol-formaldehyde cocondensates (RF condensates)], amino resins [such as melamine resins like hexamethylolmelamine and hexalokoxymethylmelamine (hexamethoxymethylmelamine, hexasubtoxymethylmelamine, etc.); urea resins like methylolurea; benzoguanamine resins like methylolbenzoguanamine resin, etc.], epoxy compounds, and isocyanate compounds. These adhesion-improving agents can be used individually or in combination of two or more.

[0183] Of these, phenolic resins and amino resins are preferred, with phenolic resins being particularly preferred.

[0184] The proportion of the fourth adhesion improver is, for example, 1 to 100 parts by mass, preferably 5 to 50 parts by mass, more preferably 8 to 40 parts by mass, more preferably 10 to 30 parts by mass, and most preferably 15 to 25 parts by mass, per 100 parts by mass of the fourth rubber component. If the proportion of the adhesion improver is too low, the effect of improving adhesion may decrease, and conversely, if it is too high, the productivity of toothed belts may decrease.

[0185] (4C) Fourth Crosslinking Compound The fourth crosslinked rubber composition may further contain a fourth crosslinking compound. Examples of fourth crosslinking compounds include a fourth crosslinking agent (vulcanizing agent) for crosslinking the fourth rubber component, as well as a fourth cocrosslinking agent, a fourth crosslinking accelerator (vulcanization accelerator), and a fourth crosslinking retarder (vulcanization retarder). Of these, the fourth crosslinking compound preferably contains at least a fourth crosslinking agent and a fourth cocrosslinking agent, and a combination of a fourth crosslinking agent and a fourth cocrosslinking agent is particularly preferred.

[0186] The fourth crosslinking agent can be selected from the crosslinking agents exemplified as the first crosslinking agent. A preferred fourth crosslinking agent is an organic peroxide.

[0187] The proportion of the fourth crosslinking agent is, for example, 1 to 20 parts by mass, preferably 3 to 10 parts by mass, and more preferably 4 to 8 parts by mass, per 100 parts by mass of the fourth rubber component.

[0188] The fourth cocrosslinking agent can be selected from the cocrosslinking agents exemplified as the first cocrosslinking agent, including preferred embodiments.

[0189] The proportion of the fourth cocrosslinking agent may be 25 parts by mass or less per 100 parts by mass of the fourth rubber component, for example, 0.01 to 25 parts by mass, preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and most preferably 0.3 to 1 part by mass.

[0190] The proportion of the fourth crosslinking compound can be selected from a range of about 0.2 to 50 parts by mass per 100 parts by mass of the fourth rubber component, for example, 0.3 to 30 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass.

[0191] (4D) Fourth Other Compounding Agent The fourth crosslinked rubber composition may further contain other compounding agents (fourth other compounding agent), such as filler compounding agents and conventional additives used in rubber compositions for toothed belts. The filler compounding agent can be selected from the filler compounding agents exemplified as the first filler compounding agent. The conventional additive can be selected from the additives exemplified as the first other compounding agent.

[0192] In particular, the proportion of metal oxides such as titanium oxide is, for example, 1 to 30 parts by mass, preferably 3 to 20 parts by mass, and more preferably 5 to 15 parts by mass, per 100 parts by mass of the fourth rubber component.

[0193] The total proportion of the fourth other compounding agent is, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 15 parts by mass, per 100 parts by mass of the fourth rubber component.

[0194] (Tooth Fabric) The tooth fabric laminated on the inner surface of the tooth rubber layer may be made of a fabric such as woven fabric, knitted fabric, or nonwoven fabric. Conventionally, it is often a woven fabric (canvas), and is made of a fabric woven from warp threads extending in the belt width direction and weft threads extending in the belt circumference direction. The weave structure of the woven fabric is not particularly limited as long as the warp and weft threads intersect regularly in the vertical and horizontal directions, and may be any of plain weave, twill weave (or diagonal weave), satin weave, or a weave structure that combines these structures. Preferred woven fabrics have a twill weave and / or satin weave structure (especially a twill weave structure).

[0195] The fibers that form the weft and warp threads of the tooth cloth include, for example, polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), polyamide fibers [aliphatic polyamide fibers such as polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers (nylon fibers), aramid fibers, etc.], polyester fibers [polyalkylene arylate fibers (for example, polyethylene terephthalate (PET) fibers, polytrimethylene terephthalate (PTT) fibers, polybutylene terephthalate (PBT) fibers, polyethylene naphthalate (PEN) fibers, etc.] ２－４ Alkilen C ８－１４ Examples of synthetic fibers include: arylate fibers; polyarylate fibers, fully aromatic polyester fibers such as liquid crystal polyester fibers, vinylon fibers, polyvinyl alcohol fibers, poly(p-phenylenebenzobisoxazole) (PBO) fibers, polyphenylene ether fibers, polyether ether ketone fibers, polyether sulfone fibers, polyurethane fibers, etc.; natural fibers such as cotton, linen, and wool; regenerated cellulose fibers such as rayon; cellulose ester fibers, etc.; and inorganic fibers such as carbon fibers and glass fibers. These fibers can be used individually or in combination of two or more types.

[0196] Of these fibers, organic fibers are commonly used, with cellulose fibers such as cotton and rayon, polyester fibers (PET fibers, etc.), polyamide fibers (aliphatic polyamide fibers such as polyamide 66 fibers, aramid fibers, etc.), PBO fibers, and fluororesin fibers [polytetrafluoroethylene (PTFE) fibers, etc.] being preferred. From the viewpoint of adhesion to the tooth rubber layer and economic efficiency, cellulose fibers, polyester fibers, and polyamide fibers are even more preferred, and polyamide fibers (especially aliphatic polyamide fibers) are even more preferred. Furthermore, composite yarns of these fibers and elastic yarns with elasticity [for example, polyurethane elastic yarns with elasticity such as spandex made of polyurethane, processed yarns that have undergone stretch processing (e.g., woolly processing, crimping processing, etc.)] are also preferred.

[0197] The form of the warp and weft threads is not particularly limited and may be monofilament yarn, which is a single long fiber; multifilament yarn, which is made by aligning or twisting filaments (long fibers); or spun yarn, which is made by twisting short fibers. The multifilament yarn or spun yarn may be a blended yarn or blended yarn using multiple types of fibers. The weft threads preferably contain elastic yarn, while the warp threads usually do not contain elastic yarn from the viewpoint of weaving. In order to ensure the elasticity of the tooth fabric in the circumferential direction of the belt, the weft threads containing elastic yarn extend in the circumferential direction of the belt, and the warp threads extend in the width direction of the belt.

[0198] The average diameter of the fibers is, for example, 1 to 100 μm (e.g., 3 to 50 μm), preferably 5 to 30 μm, and more preferably 7 to 25 μm. Regarding the average diameter (thickness) of the yarn (twisted yarn), the weft may be, for example, 100 to 1000 dtex (particularly 300 to 700 dtex), and the warp may be, for example, 50 to 500 dtex (particularly 100 to 300 dtex). The density of the weft (threads / cm) may be, for example, 5 to 50 (particularly 10 to 30), and the density of the warp (threads / cm) may be, for example, 10 to 300 (particularly 20 to 100).

[0199] The woven fabric may have a multi-layered weave structure (such as a double-layered weave structure), but in the present invention, since the inner surface of the tooth fabric is laminated with a fluororesin-containing rubber layer and a resin film layer, durability and jumping resistance can be improved without the need for a special weave structure, and therefore, a woven fabric without a multi-layered weave structure (a single-layered or single-ply woven fabric) is preferred in order to improve economic efficiency.

[0200] The present invention provides a toothed belt with excellent durability and jumping resistance without using special and expensive tooth fabrics such as multi-layered woven fabrics containing fluorine fibers. Therefore, in the present invention, tooth fabrics that do not contain fluorine fibers or tooth fabrics formed from single-layered woven fabrics are preferred, and tooth fabrics formed from single-layered woven fabrics that do not contain fluorine fibers are particularly preferred.

[0201] The average thickness of the tooth fabric (the tooth fabric in the toothed belt) is, for example, 0.1 to 2 mm, preferably 0.2 to 1.5 mm. The average thickness of the tooth fabric as raw material (the tooth fabric before molding) is, for example, 0.5 to 3 mm, preferably 0.75 to 2.5 mm.

[0202] To improve adhesion to the tooth rubber layer, the fabric forming the tooth cloth may be treated with an adhesive coating. Examples of adhesive coatings include immersing the fabric in an RFL treatment solution followed by heat drying; treating it with an epoxy compound or isocyanate compound; and dissolving a rubber composition in an organic solvent to make a rubber glue, immersing the fabric in this rubber glue, and then heat drying. These methods can be performed individually or in combination, and the order and number of treatments are not limited. For example, after immersing in the RFL treatment solution, the fabric may be further immersed in the rubber glue and then heat dried.

[0203] Furthermore, to enhance the adhesion between the tooth cloth and the tooth rubber layer, an uncrosslinked rubber sheet, formed by rolling a rubber composition, may be laminated onto the back surface (the side that adheres to the tooth rubber layer) of the cloth forming the tooth cloth. This rubber composition (crosslinked rubber composition) can be appropriately selected from the crosslinked rubber compositions exemplified as crosslinked rubber compositions for forming the tooth rubber layer described later, or it may be a conventional adhesive rubber composition. In addition, the uncrosslinked rubber sheet made of this rubber composition may form an adhesive rubber layer interposed between the tooth cloth and the tooth rubber layer in a toothed belt. The cloth subjected to the above adhesive treatment will be referred to as the tooth cloth precursor.

[0204] (Fluororesin-containing rubber layer) In this invention, the fluororesin-containing rubber layer laminated on the inner surface of the tooth cloth contains fluororesin, thereby improving the sliding properties of the inner surface of the belt.

[0205] The rubber hardness of the fluororesin-containing rubber layer is, for example, 60 to 95 on the Type A hardness scale, preferably 70 to 93, more preferably 75 to 92, even more preferably 80 to 90, and most preferably 85 to 89. If the hardness is too low, the deformation resistance may decrease, and conversely, if it is too high, the adhesiveness may decrease.

[0206] The basis weight of the fluororesin-containing rubber layer is, for example, 100 to 350 g / m². ２ Preferably 150 to 250 g / m² ２ More preferably 180 to 220 g / m² ２ If the basis weight of the fluororesin-containing rubber layer is too small, the sliding properties of the inner surface may decrease, and if it is too large, it may easily detach from the tooth cloth.

[0207] The average thickness of the fluororesin-containing rubber layer is, for example, 10 to 500 μm (particularly 10 to 100 μm), preferably 20 to 200 μm (particularly 25 to 70 μm), more preferably 27 to 60 μm, more preferably 28 to 55 μm, and most preferably 30 to 50 μm. If the thickness of the fluororesin-containing rubber layer is too thin, the sliding properties of the inner circumferential surface may decrease, potentially reducing jumping resistance. If it is too thick, it may easily detach from the tooth cloth, or its smoothness may decrease, potentially reducing jumping resistance.

[0208] In this application, since it is difficult to measure the average thickness of the fluororesin-containing rubber layer in the belt state, it is measured in the precursor state before crosslinking. More specifically, it is calculated by subtracting the average thickness of the tooth fabric precursor before lamination from the average thickness of the tooth fabric precursor with the fluororesin-containing rubber layer laminated on it. Specifically, each average thickness can be determined in accordance with JIS L 1096 (2010) by taking the average of the thickness measured at any five locations with a pressure surface diameter of 9.5 mm, a pressure of 23.5 kPa, and a pressure time of 10 seconds.

[0209] The fluororesin-containing rubber layer is formed from a fifth crosslinked rubber composition containing a fifth rubber component and a fluororesin.

[0210] (5A) Fifth rubber component The fifth rubber component of the fifth crosslinked rubber composition can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments.

[0211] In the fifth rubber component, in the HNBR / unsaturated carboxylic acid metal salt composite polymer, the mass ratio of hydrogenated nitrile rubber to unsaturated carboxylic acid metal salt is former / latter = 100 / 0 to 100 / 110, preferably 100 / 1 to 100 / 50, more preferably 100 / 2 to 100 / 30, and more preferably 100 / 3 to 100 / 10.

[0212] The proportion of the fifth rubber component may be 5 to 90% by mass in the fifth crosslinked rubber composition, preferably 10 to 80% by mass, more preferably 15 to 50% by mass, more preferably 20 to 40% by mass, and most preferably 25 to 30% by mass.

[0213] (5B) Fluororesins Fluororesins can be polymers that contain a fluorine-containing monomer as a polymerization component. Examples of fluorine-containing monomers include tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, and fluorine-containing vinyl monomers such as perfluoroalkyl vinyl ethers.

[0214] The fluororesin may be a copolymer of the fluorine-containing monomer and a copolymerizable monomer. Examples of copolymerizable monomers include olefin monomers such as ethylene and propylene; and (meth)acrylic monomers such as (meth)acrylic acid and methyl (meth)acrylate.

[0215] Specific examples of fluororesins include homopolymers such as polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF); and copolymers such as tetrafluoroethylene-hexafluoropropylene copolymer (PFEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (PETFE), chlorotrifluoroethylene-ethylene copolymer (PECTFE), tetrafluoroethylene-hexafluoropropylene-perfluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroethylene-chlorotrifluoroethylene copolymer, and tetrafluoroethylene-4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole copolymer.

[0216] These fluororesins can be used individually or in combination of two or more. Of these, polymers containing tetrafluoroethylene units such as PTFE, PETFE, and PFA are preferred, with PTFE being particularly preferred.

[0217] Examples of the shape of the fluororesin include granular (particulate or powdery), fibrous (such as short fibers), rod-shaped, and plate-shaped. Of these, granular, short fiber-shaped, and rod-shaped are preferred, with granular being particularly preferred, because they improve dispersibility in the fluororesin-containing rubber layer. The granular shape may be spherical, ellipsoidal, polyhedral, or irregularly shaped, for example.

[0218] When the fluororesin is in granular form, the average particle size of the granular fluororesin is, for example, 1 to 100 μm, preferably 3 to 80 μm, more preferably 5 to 50 μm, more preferably 7 to 30 μm, and most preferably 8 to 20 μm. If the average particle size of the granular fluororesin is too small, it may be difficult to uniformly disperse the granular fluororesin in the fluororesin-containing rubber layer, and if it is too large, the effect of reducing the coefficient of friction and improving wear resistance may decrease.

[0219] In this application, the average particle diameter of the granular fluororesin refers to the average value of the particle diameters measured for any 20 particles in an electron microscope image of a cross-section of the fluororesin-containing rubber layer (the particle diameter of a single particle is the average value of the major axis diameter and the minor axis diameter).

[0220] The proportion of fluororesin is, for example, 10 to 1000 parts by mass, preferably 50 to 500 parts by mass, more preferably 100 to 300 parts by mass, more preferably 150 to 250 parts by mass, and most preferably 170 to 230 parts by mass, per 100 parts by mass of the fifth rubber component. If the proportion of fluororesin is too low, the sliding properties may decrease, and if it is too high, the adhesion to the tooth cloth and the resin film layer may decrease.

[0221] (5C) Fifth Adhesion Improving Agent The fifth crosslinked rubber composition may contain a fifth adhesion improving agent, as it can improve adhesion to the tooth cloth and the resin film layer.

[0222] The fifth adhesion improving agent can be selected from the adhesion improving agents exemplified as the fourth adhesion improving agent, including preferred embodiments.

[0223] The range of the ratio of the fifth adhesion improver to the fifth rubber component can be selected from the range described as the ratio of the fourth adhesion improver to the fourth rubber component, including preferred ranges.

[0224] (5D) Fifth Crosslinking Compound The fifth crosslinked rubber composition may further contain a fifth crosslinking compound. Examples of fifth crosslinking compounds include a fifth crosslinking agent (vulcanizing agent) for crosslinking the fifth rubber component, as well as a fifth cocrosslinking agent, a fifth crosslinking aid (vulcanization aid), a fifth crosslinking accelerator (vulcanization accelerator), a fifth crosslinking retarder (vulcanization retarder), and the like. Of these, the fifth crosslinking compound preferably contains at least a fifth crosslinking agent and a fifth cocrosslinking agent (crosslinking aid), and a combination of a fifth crosslinking agent and a fifth cocrosslinking agent is particularly preferred.

[0225] The fifth crosslinking agent can be selected from the crosslinking agents exemplified as the first crosslinking agent. Of the crosslinking agents, it is preferable that one contains an organic peroxide, and a combination of an organic peroxide and a sulfur-based crosslinking agent is particularly preferred.

[0226] The proportion of the fifth crosslinking agent is, for example, 1 to 30 parts by mass, preferably 5 to 25 parts by mass, and more preferably 10 to 20 parts by mass, per 100 parts by mass of the fifth rubber component.

[0227] The proportion of organic peroxide is, for example, 1 to 30 parts by mass, preferably 5 to 25 parts by mass, and more preferably 10 to 20 parts by mass, per 100 parts by mass of the fifth rubber component.

[0228] The proportion of the sulfur-based crosslinking agent is, for example, 0.01 to 5 parts by mass, preferably 0.05 to 1 part by mass, and more preferably 0.1 to 0.5 parts by mass, per 100 parts by mass of the fifth rubber component.

[0229] The fifth co-crosslinking agent can be selected from the co-crosslinking agents exemplified as the first co-crosslinking agent. Among the co-crosslinking agents, metal salts of unsaturated carboxylic acids [polyvalent metal salts of (meth)acrylic acid such as zinc (meth)acrylate] and bismaleimides (arene bismaleimides such as N,N'-m-phenylenedimaleimide or aromatic bismaleimides) are preferred, and a combination of a metal salt of an unsaturated carboxylic acid and bismaleimides is particularly preferred.

[0230] The proportion of the fifth cocrosslinking agent may be 50 parts by mass or less per 100 parts by mass of the fifth rubber component, for example, 1 to 50 parts by mass, preferably 5 to 40 parts by mass, and more preferably 10 to 30 parts by mass.

[0231] The proportion of the metal salt of the unsaturated carboxylic acid is, for example, 1 to 50 parts by mass, preferably 3 to 40 parts by mass, more preferably 5 to 30 parts by mass, and more preferably 10 to 25 parts by mass, per 100 parts by mass of the fifth rubber component.

[0232] The proportion of bismaleimides is, for example, 0.1 to 10 parts by mass, preferably 0.2 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, and more preferably 0.4 to 1 part by mass, per 100 parts by mass of the fifth rubber component.

[0233] The proportion of the fifth crosslinking compound can be selected from a range of about 3 to 100 parts by mass per 100 parts by mass of the fifth rubber component, for example, 5 to 80 parts by mass, preferably 10 to 70 parts by mass, more preferably 20 to 50 parts by mass, and more preferably 30 to 40 parts by mass.

[0234] (5E) Fifth Other Compounding Agent The fifth crosslinked rubber composition may further contain other compounding agents (fifth other compounding agent), such as filler compounding agents and conventional additives used in rubber compositions for toothed belts. The filler compounding agent can be selected from the filler compounding agents exemplified as the first filler compounding agent. The conventional additive can be selected from the additives exemplified as the first other compounding agent.

[0235] In particular, the proportion of metal oxides such as titanium oxide is, for example, 1 to 30 parts by mass, preferably 3 to 20 parts by mass, and more preferably 5 to 15 parts by mass, per 100 parts by mass of the fifth rubber component.

[0236] The total proportion of the fifth other compounding agent is, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 15 parts by mass, per 100 parts by mass of the fifth rubber component.

[0237] (Resin film layer) In the present invention, durability and jumping resistance can be improved by laminating a resin film layer on the inner circumferential surface of the fluororesin-containing rubber layer.

[0238] The resin film layer contains a thermoplastic resin. Examples of thermoplastic resins include polyolefin resins (polyethylene resins, polypropylene resins, etc.), vinyl resins (polyvinyl chloride resins, etc.), styrene resins (polystyrene resins, etc.), acrylic resins (polymethyl methacrylate resins, etc.), vinyl alcohol resins (ethylene vinyl alcohol resins, etc.), and polyester resins (polyethylene terephthalate, polyethylene naphthalate, etc.). ２－４ Examples include alkylene-arylate resins, fully aromatic polyester resins such as liquid crystal polyester resins, polycarbonate resins (such as bisphenol A polycarbonate), polyamide resins (such as aliphatic polyamide resins like polyamide 6 and polyamide 66, and fully aromatic polyamide resins such as aramid resins), and polyurethane resins. These thermoplastic resins can be used individually or in combination of two or more types.

[0239] Of these, polyolefin resins, polyamide resins, and polyurethane resins are preferred because they can effectively improve the smoothness of the inner circumferential surface, and polypropylene resins, aliphatic polyamide resins, and polyurethane elastomers are particularly preferred. Generally, polyamide resins have a high coefficient of friction and are presumed to be unfavorable for sliding, but surprisingly, they are advantageous in improving sliding properties, perhaps because they can effectively smooth the uneven structure of the inner circumferential surface and can effectively exhibit a cooperative effect with fluororesins.

[0240] Polypropylene resins may include, for example, polypropylene, copolymers of propylene and copolymerizable monomers (binary copolymers such as propylene-ethylene copolymers and propylene-(meth)acrylic acid copolymers; and terpolymers such as propylene-ethylene-butene-1). Of these polypropylene resins, polypropylene (a homopolymer of propylene) is preferred. Polypropylene resins can be used alone or in combination of two or more types.

[0241] Aliphatic polyamide resins can be formed from aliphatic monomer units derived from aliphatic monomer components. Examples of aliphatic polyamide resins include homopolyamides of aliphatic diamines and aliphatic dicarboxylic acids, such as polyamide 46, polyamide 66, polyamide 610, and polyamide 612; homopolyamides of aliphatic aminocarboxylic acids and / or corresponding lactams, such as polyamide 6, polyamide 11, and polyamide 12; and copolymers (copolyamides) of multiple aliphatic monomer components, such as copolyamide 6 / 66, copolyamide 6 / 11, and copolyamide 66 / 12. Of these, aliphatic polyamide resins containing an aliphatic monomer component having an alkylene group with, for example, 4 to 12, preferably 6 to 11, and more preferably 6 to 9 carbon atoms are preferred.

[0242] The polyurethane elastomer may be, for example, a polyester-type polyurethane elastomer, a polyether-type polyurethane elastomer, or a polycarbonate-type polyurethane elastomer.

[0243] The melting point of the thermoplastic resin can be selected from a range of, for example, 100 to 250°C. In the case of polypropylene resins, it is preferably 130 to 180°C, more preferably 140 to 170°C, and in the case of aliphatic polyamide resins, it is preferably 150 to 240°C, more preferably 200 to 230°C. If the melting point of the thermoplastic resin is too low, the fluidity during crosslinking may become too high, making it difficult to form a uniform inner surface. If it is too high, the adhesion to the fluororesin-containing rubber layer may decrease.

[0244] The resin film layer may be formed from a resin composition containing a thermoplastic resin. The resin composition may further contain conventional additives blended with the thermoplastic resin. Examples of conventional additives include fillers, dispersants, softeners, plasticizers, antioxidants, colorants, stabilizers (such as UV absorbers and heat stabilizers), flame retardants, and antistatic agents. The proportion of conventional additives is, for example, 30 parts by mass or less, preferably 20 parts by mass or less, and more preferably 10 parts by mass or less (for example, 0.1 to 10 parts by mass) per 100 parts by mass of the thermoplastic resin.

[0245] The proportion of thermoplastic resin in the resin film layer may be 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and may also be 100% by mass.

[0246] The average thickness of the resin film layer can be selected from a range of approximately 10 to 150 μm (particularly 20 to 120 μm), for example, 10 to 100 μm, preferably 20 to 80 μm (particularly 25 to 65 μm), more preferably 30 to 70 μm, more preferably 35 to 65 μm, and most preferably 40 to 60 μm. If the resin film layer is too thin, durability may decrease and the smoothness of the inner surface may decrease. If it is too thick, jumping resistance may decrease and the interlocking may not be maintained well due to its susceptibility to abrasion.

[0247] In this application, the average thickness of the resin film layer can be determined by observing it with a microscope and taking the average value of any 10 points on the tooth root.

[0248] [Tooth root] The laminate (resin film layer) constitutes the surface of the tooth, as well as the surface on the tooth side of the back (the surface of the tooth root).

[0249] In the dorsal portion corresponding to the tooth root, a tooth rubber layer may be interposed between the tooth cloth and the core wire, but the tooth cloth and core wire may also be in contact without the tooth rubber layer. Even when a tooth rubber layer is interposed in the dorsal portion corresponding to the tooth root, the thickness of the tooth rubber layer is formed to be thinner than that of the tooth portion.

[0250] [Back Rubber Layer] The back portion has the teeth and tooth roots formed on its inner circumferential surface, and on its outer circumferential surface side, it has a back rubber layer that forms the outer circumferential surface of the belt. Furthermore, the back rubber layer is made of a crosslinked rubber composition (sixth crosslinked rubber composition). In the embodiments of Figures 1 and 5, the other surface on the side where the teeth are not formed (the back of the belt) is not made of fabric (woven fabric, knitted fabric, nonwoven fabric, etc.), but it may be made of fabric if necessary. This fabric can be selected from the fabrics exemplified as tooth fabrics, including in preferred embodiments.

[0251] The rubber hardness of the back rubber layer is, for example, 60 to 95 on a Type A hardness scale, preferably 70 to 93, more preferably 75 to 90, even more preferably 78 to 88, and most preferably 80 to 85. If the hardness is too low, the deformation resistance may decrease, and conversely, if it is too high, the adhesion to the core wire and the tooth rubber layer may decrease.

[0252] The average thickness of the back rubber layer is, for example, 0.3 to 3 mm, preferably 0.5 to 2 mm. The average thickness of the back portion (average thickness of the back portion at the tooth root) is, for example, 1 to 5 mm, preferably 1.5 to 4 mm.

[0253] (Sixth Crosslinked Rubber Composition) The sixth crosslinked rubber composition that forms the back rubber layer is not particularly limited as long as it contains the sixth rubber component and does not impair the adhesion between the back rubber layer and the teeth.

[0254] (6A) Sixth Rubber Component The sixth rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The sixth rubber component is preferably of the same series or type as the rubber component of the tooth rubber layer, and more preferably of the same type, in order to improve adhesion with the tooth.

[0255] In the sixth rubber component, in the HNBR / unsaturated carboxylic acid metal salt composite polymer, the mass ratio of hydrogenated nitrile rubber to unsaturated carboxylic acid metal salt is former / latter = 100 / 1 to 100 / 50, preferably 100 / 3 to 100 / 30, and more preferably 100 / 5 to 100 / 20.

[0256] The proportion of the sixth rubber component may be 10 to 95% by mass in the sixth crosslinked rubber composition, preferably 30 to 93% by mass, more preferably 50 to 90% by mass, more preferably 50 to 80% by mass, and most preferably 60 to 70% by mass.

[0257] (6B) Sixth Filler Examples of the sixth filler include the fillers exemplified as the first filler. The fillers can be used alone or in combination of two or more. Among the fillers, the sixth filler is preferably a sixth reinforcing filler, and carbon black and silica are particularly preferred.

[0258] The range of the average particle size and iodine adsorption amount of carbon black in the sixth reinforcing filler can be selected from the ranges described as the average particle size and iodine adsorption amount of carbon black in the first reinforcing filler, including the preferred ranges.

[0259] The proportion of carbon black may be, for example, 100 parts by mass or less, preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 10 parts by mass or less, and most preferably 5 parts by mass or less (e.g., 1 to 5 parts by mass) based on 100 parts by mass of the sixth rubber component.

[0260] Silica includes dry silica, wet silica, surface-treated silica, etc. Also, silica can be classified into, for example, dry-process white carbon, wet-process white carbon, colloidal silica, precipitated silica, etc. according to the production method. These silicas can be used alone or in combination of two or more. Among these silicas, silica having a surface silanol group (anhydrous silicic acid, hydrous silicic acid) is preferred, and hydrous silicic acid having many surface silanol groups has a strong chemical bonding force with the rubber component.

[0261] The average particle size (average primary particle size) of silica is, for example, 1 to 500 nm, preferably 3 to 300 nm, more preferably 5 to 100 nm, and still more preferably 10 to 50 nm.

[0262] Also, the nitrogen adsorption specific surface area of silica by the BET method is, for example, 50 to 400 m ２ / g, preferably 100 to 300 m ２ / g, more preferably 150 to 200 m ２ / g.

[0263] The proportion of silica may be, for example, 100 parts by mass or less, preferably 1 to 80 parts by mass, more preferably 10 to 70 parts by mass, still more preferably 20 to 60 parts by mass, and most preferably 30 to 50 parts by mass based on 100 parts by mass of the sixth rubber component.

[0264] The proportion of the sixth filler may be, for example, 100 parts by mass or less per 100 parts by mass of the sixth rubber component, preferably 1 to 80 parts by mass, more preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, and most preferably 30 to 50 parts by mass.

[0265] (6C) Sixth Crosslinking Compound The sixth crosslinking rubber composition may further contain a sixth crosslinking compound. Examples of sixth crosslinking compounds include sixth crosslinking agents (vulcanizing agents) for crosslinking the sixth rubber component, as well as sixth co-crosslinking agents, sixth crosslinking aids (vulcanization aids), sixth crosslinking accelerators (vulcanization accelerators), sixth crosslinking retarders (vulcanization retarders), and so on. Of these, the sixth crosslinking compound preferably contains at least a sixth crosslinking agent, and may be a combination of a sixth crosslinking agent and a sixth co-crosslinking agent (crosslinking aid).

[0266] The sixth crosslinking agent can be selected from the crosslinking agents exemplified as the first crosslinking agent, including preferred embodiments.

[0267] The range of the ratio of organic peroxide to the sixth rubber component in the sixth crosslinking compound can be selected from the range described as the ratio of organic peroxide to the first rubber component in the first crosslinking compound, including preferred ranges.

[0268] The proportion of the metal oxide is, for example, 0.1 to 30 parts by mass, preferably 0.3 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and more preferably 1 to 3 parts by mass, per 100 parts by mass of the sixth rubber component.

[0269] The sixth co-crosslinking agent can be selected from the co-crosslinking agents exemplified as the first co-crosslinking agent, including preferred embodiments.

[0270] The proportion of the sixth co-crosslinking agent may be 25 parts by mass or less (for example, 0.2 to 25 parts by mass) per 100 parts by mass of the sixth rubber component, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less.

[0271] The proportion of the sixth crosslinking compound can be selected from a range of about 0.2 to 50 parts by mass per 100 parts by mass of the sixth rubber component, for example, 0.3 to 30 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass, and more preferably 2 to 5 parts by mass.

[0272] (6D) Sixth Other Compounding Agent The sixth crosslinked rubber composition may further contain, as other compounding agents (sixth other compounding agent), sixth short fibers, conventional additives used in rubber compositions for toothed belts, etc. The sixth short fibers can be selected from the short fibers exemplified as first short fibers. The conventional additives can be selected from the additives exemplified as first other compounding agents.

[0273] In particular, the proportion of the plasticizer is, for example, 1 to 30 parts by mass, preferably 3 to 20 parts by mass, and more preferably 5 to 15 parts by mass, per 100 parts by mass of the sixth rubber component.

[0274] The total proportion of the sixth other compounding agent is, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 15 parts by mass, per 100 parts by mass of the sixth rubber component.

[0275] [Core wires] On the back of the belt, core wires extending along the belt circumferential direction are embedded on the inner circumference side of the back rubber layer. These core wires act as tensile members, improving the running stability and strength of the toothed belt. Furthermore, on the back, core wires, which are usually twisted cords extending along the belt circumferential direction, are embedded at predetermined intervals in the belt width direction. Multiple core wires parallel to the longitudinal direction may be arranged, but from the viewpoint of productivity, they are usually embedded in a spiral shape. When arranged in a spiral shape, the angle of the core wires with respect to the longitudinal direction of the belt may be, for example, 5° or less, and from the viewpoint of belt running performance, it is preferable that it is as close to 0° as possible.

[0276] More specifically, the core wires may be embedded at predetermined intervals (or pitches) (or at equal intervals) from one end to the other in the belt width direction on the back, as shown in Figure 1. The spacing (spinning pitch), which is the distance between the centers of adjacent core wires, should be greater than the core wire diameter, and depending on the core wire diameter, it may be, for example, 0.5 to 3.5 mm, preferably 0.8 to 3 mm, and more preferably 1 to 2.8 mm.

[0277] The core wire may be formed from a twisted cord made by twisting together multiple strands or multifilament threads. Of these, a twisted cord of strands is preferred, and one strand may be formed by bundling filaments (long fibers). There are no particular limitations on the thickness of the filaments forming the twisted cord, the number of filaments converged, the number of strands, and the twist configuration.

[0278] The twisted cord forming the core wire may be a single-strand, double-strand, or Lang-strand cord. By using a Lang-strand core wire, where the twist direction of the lower twist and the twist direction of the upper twist are the same, the bending stiffness is lower compared to double-strand or single-strand cords, resulting in excellent bending fatigue resistance.

[0279] The fibers forming the core are not particularly limited, and examples include synthetic fibers such as polyester fibers (polyalkylelelate fibers, poly(p-phenylene naphthalate) fibers), polybenzoxazole fibers, acrylic fibers, and polyamide fibers (aliphatic polyamide fibers, aramid fibers, etc.), as well as inorganic fibers such as glass fibers, carbon fibers, and metal fibers (steel fibers). These fibers can be used individually or in combination of two or more types. From the viewpoint of low elongation and high strength, synthetic fibers such as polyester fibers and polyamide fibers, and inorganic fibers such as glass fibers and carbon fibers are commonly used as fibers forming the core.

[0280] In applications where particularly high loads are applied, multifilament carbon fiber yarns are preferably used. Examples of carbon fibers used include those manufactured by Toray Industries, Inc., under the trade name "Torayca".

[0281] Carbon fiber multifilament yarns can be selected from multifilament yarns with different filament counts, such as 6K and 12K. 6K refers to a multifilament yarn with 6,000 filaments, and 12K refers to a multifilament yarn with 12,000 filaments. The fineness of 6K multifilament yarn is approximately 400 tex, and the fineness of 12K multifilament yarn is approximately 800 tex.

[0282] If the fineness of carbon fiber multifilament yarn is greater than 1000 tex, there is a risk that its flexural fatigue resistance will decrease. Conversely, if the fineness of carbon fiber multifilament yarn is less than 300 tex, the material cost will increase, and the number of under-twisted yarns required to produce a core wire with sufficient tensile strength will increase, leading to an increase in labor costs.

[0283] In one embodiment of the toothed belt of the present invention, a carbon fiber cord (12K-1 / 0) made by single-twisting one strand of 12K multifilament yarn (fineness approximately 800 tex) is used as the core wire. Alternatively, a Lang-twisted carbon fiber cord (12K-1 / 4) may be used as the core wire, made by first twisting one strand of 12K multifilament yarn (fineness approximately 800 tex) to create a pre-twisted yarn, and then combining four of these pre-twisted yarns and twisting them together. Note that "12K-1 / 0" indicates a twisted cord made by single-twisting one strand of 12K multifilament yarn, and "12K-1 / 4" indicates a twisted cord made by first twisting one strand of 12K multifilament yarn to create a pre-twisted yarn, and then combining four of these pre-twisted yarns and twisting them together. Similarly, for example, "12K-1 / 3" indicates a twisted cord made by first twisting one 12K multifilament yarn to create a base twist, and then twisting three of these base twists together. "12K-4 / 0" indicates a twisted cord made by twisting four 12K multifilament yarns together in a single-ply twist.

[0284] The core wire may be subjected to an adhesive treatment to enhance its adhesion to the crosslinked rubber composition. For example, the adhesive treatment may involve immersing the stranded cord in a resorcinol-formaldehyde-latex treatment solution (RFL treatment solution), followed by heating and drying to form a uniform adhesive layer on the surface of the stranded cord. The RFL treatment solution is a mixture of latex and an initial condensate of resorcinol and formalin. The latex may be, for example, chloroprene rubber, styrene-butadiene-vinylpyridine terpolymer (VP latex), nitrile rubber, or hydrogenated nitrile rubber. Furthermore, the adhesive treatment may involve pre-treating with an epoxy compound or isocyanate compound before treatment with the RFL treatment solution.

[0285] The average diameter (average wire diameter) of the stranded cord (or core wire) is, for example, 0.2 to 2.5 mm, preferably 0.5 to 2.3 mm, more preferably 0.7 to 2.2 mm, and 0.8 to 2.1 mm is preferred for applications where particularly high loads are applied. If the core wire diameter is too thin, the elongation of the core wire will increase, which may cause tooth breakage (loss of teeth). If the core wire diameter is too thick, the fatigue resistance of the core wire will decrease, which may cause core wire breakage. In one embodiment of the present invention, the core wire diameter is adjusted to 1.0 mm.

[0286] <Method for manufacturing a toothed belt> The toothed belt of the present invention may be manufactured, for example, by the following method (pre-forming method).

[0287] [Preparation process for tooth rubber layer precursor and back rubber layer precursor] In the preparation process for tooth rubber layer precursor and back rubber layer precursor, uncrosslinked rubber sheets that form multiple rubber layers are prepared (for example, a first rubber layer precursor which is an uncrosslinked rubber sheet that forms the first rubber layer (surface rubber layer), a second rubber layer precursor which is an uncrosslinked rubber sheet that forms the second rubber layer (internal rubber layer), and a back rubber layer precursor which is an uncrosslinked rubber sheet that forms the back rubber layer).

[0288] In particular, if the first rubber layer precursor contains first short fibers, it is preferable to subject it to the first rubber layer precursor preparation process shown below in order to orient the first short fibers in a predetermined direction.

[0289] In the first rubber layer precursor preparation step, the first short fibers can be oriented (arranged) in a predetermined direction during the process of preparing an uncrosslinked rubber sheet by rolling the rubber composition, which has been kneaded in a Banbury mixer or the like, using rolls or a calender. Specifically, a conventional method for oriented the first short fibers in a predetermined direction (one direction on the sheet surface) is to pass the rubber between a pair of calender rolls with a predetermined gap between them and roll it into a sheet, thereby obtaining a rolled sheet in which the first short fibers are oriented in the rolling direction.

[0290] The same method can be used to orient the short fibers when the second rubber layer and the back rubber layer contain short fibers (especially when the second rubber layer contains second short fibers).

[0291] [Toothcloth Precursor Preparation Process] In the toothcloth precursor preparation process, a toothcloth precursor is prepared for forming the toothcloth. Specifically, in the toothcloth precursor preparation process, the toothcloth precursor is prepared by laminating a fluororesin-containing rubber layer onto the inner surface of the toothcloth. Methods for laminating the fluororesin-containing rubber layer include applying a rubber adhesive of the fifth rubber composition containing the fifth rubber component and fluororesin to the inner surface of the toothcloth (coating method or spreading method); and laminating a sheet formed from the fifth rubber composition onto one side of the second precursor (the side in contact with the tooth rubber layer). Note that a toothcloth that has been bonded may be used, and if an adhesive rubber layer is to be formed between the toothcloth and the tooth rubber layer, the adhesive rubber layer may be formed on the outer surface of the toothcloth after the fluororesin-containing rubber layer has been formed.

[0292] [Pre-molding process] Next, a precursor for forming a resin film layer and a tooth cloth precursor for forming a tooth cloth are sequentially wound around the outer surface of a cylindrical mold having a plurality of grooves (recesses) corresponding to the teeth of a toothed belt. Subsequently, if the first rubber layer precursor contains first short fibers, a first rubber layer precursor, which is an uncrosslinked rubber sheet for forming the first rubber layer (surface rubber layer), and a second rubber layer precursor, which is an uncrosslinked rubber sheet for forming the second rubber layer (internal rubber layer), are sequentially wound around the outer surface of the tooth cloth precursor, with the orientation direction of the first short fibers of the first rubber layer precursor oriented in the direction of the belt's longitudinal direction, to form a laminate. The laminate is then heated in a predetermined apparatus to a temperature (for example, about 70 to 90°C) at which the rubber composition softens, and pressure is applied to the laminate from the outer surface to press the rubber composition of the uncrosslinked rubber sheet and the tooth cloth precursor into the grooves (recesses) of the cylindrical mold to form teeth and obtain a semi-crosslinked pre-molded body. In this press-fitting process to form the teeth, a resin film layer laminated on the surface of the tooth cloth via a fluororesin-containing rubber layer stretches to conform to the contour of the teeth and is positioned on the outermost surface. Inside this, a first rubber layer is positioned along the contour of the teeth, and the first short fibers are also arranged in the direction of the contour of the teeth while remaining aligned in the longitudinal direction of the belt. Furthermore, a second rubber layer is positioned inside, forming a layered structure. If the teeth do not include tooth cloth, a first rubber layer precursor is wrapped around the outer surface of the cylindrical mold instead of a tooth cloth precursor.

[0293] Furthermore, a method for obtaining a semi-crosslinked preform may be used in which, instead of a cylindrical mold, a flat press mold (flat mold) having multiple grooves (recesses) corresponding to the teeth is used, and the rubber composition of the uncrosslinked rubber sheet and the tooth fabric precursor are pressed into the grooves (recesses) of the flat mold by heating and pressing in the procedure described above to form the teeth. In this method, after demolding the preform from the flat mold, the preform is wrapped around and mounted (fitting the teeth and grooves) onto a cylindrical mold having multiple grooves (recesses) corresponding to the teeth, and the process moves to the next step.

[0294] [Crosslinking Molding Process] A stranded cord constituting the core wire is wound spirally around the outer surface of the obtained pre-molded body at a predetermined pitch (so that the pitch is predetermined in the axial direction of the cylindrical mold). Furthermore, a back rubber layer precursor, which is an uncrosslinked rubber sheet that forms the back rubber layer, is wound around the outer surface to form an uncrosslinked belt molded body (uncrosslinked laminate).

[0295] Next, with the uncrosslinked belt molded body positioned on the outer circumference of the cylindrical mold, a rubber jacket, which acts as a vapor barrier, is placed over it. Subsequently, the jacketed belt molded body and the cylindrical mold are housed inside a crosslinking molding device such as a vulcanizing vessel. When the belt molded body is heated and pressurized inside the crosslinking molding device, the desired shape is formed, and the crosslinking reaction of the uncrosslinked and semi-crosslinked rubber components contained in the belt molded body causes each component to join together and harden integrally, forming a sleeve-shaped crosslinked molded body (crosslinked belt sleeve).

[0296] [Cutting Process] Finally, multiple toothed belts are obtained by cutting the bridging belt sleeve, which has been demolded from the cylindrical mold, to a predetermined width.

[0297] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The raw materials used, preparation methods, evaluation methods, etc., are shown below.

[0298] [Rubber Composition] Table 1 shows the formulations of the rubber composition that forms the fluororesin-containing rubber layer, adhesive rubber layer, tooth rubber layer, and back rubber layer.

[0299]

[0300] [Materials for the rubber composition] HNBR: Zetpol 2010 manufactured by Nippon Zeon Co., Ltd., iodine value 11 mg / 100 mg HNBR containing unsaturated carboxylate metal salt: Zeoforte ZSC2295CX manufactured by Nippon Zeon Co., Ltd., base HNBR: unsaturated carboxylate metal salt (mass ratio) = 100:110, iodine value of base HNBR 28 mg / 100 mg Nylon staple fibers: Polyamide 66, Leona manufactured by Asahi Kasei Corporation, average fiber length 3 mm, average fiber diameter 27 μm Aramid staple fibers: Conex manufactured by Teijin Limited, average fiber length 3 mm, average fiber diameter 14 μm Stearic acid: Tsubaki Stearic Acid manufactured by NOF Corporation Carbon black SRF: Seest S manufactured by Tokai Carbon Co., Ltd., average particle size 66 nm, iodine adsorption amount 26 mg / g Silica: "UltraSil VN-3" manufactured by Evonik Degussa Japan Co., Ltd., specific surface area 155-195 m² ２ / g Calcium carbonate: Maruo Calcium Co., Ltd. "Super #1500", average particle size 1.5 μm Zinc oxide: Sakai Chemical Industry Co., Ltd. "Zinc Oxide Type 2", average particle size 0.55 μm Plasticizer: ADEKA Corporation "ADEKA Sizer RS700" Anti-aging agent: p,p'-dioctyl diphenylamine, Seiko Chemical Co., Ltd. "Nonflex OD3" Organic peroxide: 1,3-bis(t-butylperoxyisopropyl)benzene, theoretical active oxygen content 9.45% Co-crosslinking agent 1: N,N'-m-phenylenedimaleimide, Ouchi Shinko Chemical Co., Ltd. "Balnok PM" Co-crosslinking agent 2: Zinc methacrylate, Asada Chemical Industry Co., Ltd. "R-20S" Titanium dioxide: Cosmo Chemical Co., Ltd. "COTIOX KA-100" Phenolic resin: RP-12687 manufactured by Sumitomo Bakelite Co., Ltd. Sulfur: MIDAS manufactured by Migen Chemical Co., Ltd. Fluoropolymer: Low molecular weight PTFE, MP-1300-J manufactured by Mitsui Chemours Fluoroproducts Co., Ltd., average particle size 11 μm

[0301] [Rubber Hardness of Crosslinked Rubber] A block of uncrosslinked rubber composition having the composition shown in Table 1 was passed through a calender roll to prepare an uncrosslinked rolled rubber sheet of a predetermined thickness. The obtained uncrosslinked rolled rubber sheet was then press-heated at a temperature of 165°C for 30 minutes to produce a crosslinked rubber sheet (100 mm × 100 mm × 2 mm thickness). A laminate of three crosslinked rubber sheets was used as a sample, and the rubber hardness (Type D or Type A) of the crosslinked rubber sheet was measured using a Type D or Type A durometer in accordance with the spring durometer hardness test specified in JIS K 6253 (2012) (Vulcanized rubber and thermoplastic rubber - Method for determining hardness -). The test temperature was 23°C.

[0302] [Twisted cord for core wire] (Twisted cord A) A carbon fiber cord (12K-1 / 0, tensile modulus of elasticity 230 GPa) was prepared by twisting one strand of 12K multifilament yarn [Toray Industries, Inc. "Torayca T700SC-12000", single yarn fineness 0.67 dtex, total fineness 800 tex] into a single strand, and then bonded with an HNBR-based overcoat treatment agent to obtain a twisted cord A for core wire with a wire diameter of 1.0 mm.

[0303] (Twisted cord B) One 12K multifilament yarn [Toray Industries, Inc. "Torayca T700SC-12000", single yarn fineness 0.67 dtex, total fineness 800 tex] was pre-twisted to produce a pre-twisted yarn, and four of these pre-twisted yarns were combined and pre-twisted to produce a Lang-twisted carbon fiber cord (12K-1 / 4, tensile modulus 230 GPa). This was then bonded with an HNBR-based overcoat treatment agent to obtain a core wire twisted cord B with a wire diameter of 2.0 mm.

[0304] [Tooth cloth and processing of tooth cloth] (Examples 1-22 and Comparative Examples 4-6) Tooth cloth precursors were prepared by immersing the woven fabrics shown in Table 2 with RFL processing solution and rubber glue. Specifically, for the RFL processing, two types of RFL processing solutions (RFL1, RFL2) shown in Table 3 were used, and the immersion treatment was performed in the order of RFL1, then RFL2. Subsequently, for the rubber glue treatment, two types of rubber glue (rubber glue 1, rubber glue 2) shown in Table 4 were used, and the immersion treatment was performed in the order of rubber glue 1, then rubber glue 2 to obtain processed canvas.

[0305]

[0306]

[0307]

[0308] In Examples 1, 3-7, 19, 21 and Comparative Example 4, 200 g / m² of rubber adhesive, prepared by dissolving 40 parts by mass of rubber composition R1 in 100 parts by mass of solvent (methyl ethyl ketone), was applied to the surface side (inner circumference side) of the treated canvas. ２ After applying the spreading treatment, 100 g / m² of rubber adhesive, prepared by dissolving 25 parts by mass of rubber composition R2 in 100 parts by mass of solvent (methyl ethyl ketone), is applied to the back side (outer surface of the belt). ２ A spreading treatment was performed to apply the material, and tooth cloth precursor 1 was obtained.

[0309] In Examples 2, 8-14, 20, 22 and Comparative Example 5, 200 g / m² of rubber adhesive, prepared by dissolving 40 parts by mass of rubber composition R1 in 100 parts by mass of solvent (methyl ethyl ketone), was applied to the surface side (inner circumference side) of the treated canvas. ２ After applying the spreading treatment, 100 g / m² of rubber adhesive, prepared by dissolving 25 parts by mass of rubber composition R6 in 100 parts by mass of solvent (methyl ethyl ketone), is applied to the back side (outer surface of the belt). ２ A spreading treatment was performed to apply the material, and tooth cloth precursor 2 was obtained.

[0310] The average thickness of the fluororesin-containing rubber layer (precursor) in tooth cloth precursors 1 and 2 was 40 μm.

[0311] In Comparative Example 6, 100 g / m² of rubber adhesive, prepared by dissolving 25 parts by mass of rubber composition R6 in 100 parts by mass of solvent (methyl ethyl ketone), was applied only to the back side (outer belt side) of the treated canvas. ２ A spreading treatment was performed to apply the material, and tooth cloth precursor 3 was obtained.

[0312] In Example 15, 100 g / m of rubber adhesive, prepared by dissolving 40 parts by mass of rubber composition R1 in 100 parts by mass of solvent (methyl ethyl ketone), was applied to the surface side (inner circumference side of the belt) of the treated canvas. ２After applying the spreading treatment, 100 g / m² of rubber adhesive, prepared by dissolving 25 parts by mass of rubber composition R6 in 100 parts by mass of solvent (methyl ethyl ketone), is applied to the back side (outer surface of the belt). ２ A spreading treatment was performed to apply the material, and tooth cloth precursor 6 was obtained.

[0313] The average thickness of the fluororesin-containing rubber layer (precursor) in tooth cloth precursor 6 was 25 μm.

[0314] In Example 16, 150 g / m² of rubber adhesive, prepared by dissolving 40 parts by mass of rubber composition R1 in 100 parts by mass of solvent (methyl ethyl ketone), was applied to the surface side (inner circumference side) of the treated canvas. ２ After applying the spreading treatment, 100 g / m² of rubber adhesive, prepared by dissolving 25 parts by mass of rubber composition R6 in 100 parts by mass of solvent (methyl ethyl ketone), is applied to the back side (outer surface of the belt). ２ A spreading treatment was performed to apply the material, and tooth cloth precursor 7 was obtained.

[0315] The average thickness of the fluororesin-containing rubber layer (precursor) in tooth cloth precursor 7 was 30 μm.

[0316] In Example 17, 300 g / m of rubber adhesive, prepared by dissolving 40 parts by mass of rubber composition R1 in 100 parts by mass of solvent (methyl ethyl ketone), was applied to the surface side (inner circumference side of the belt) of the treated canvas. ２ After applying the spreading treatment, 100 g / m² of rubber adhesive, prepared by dissolving 25 parts by mass of rubber composition R6 in 100 parts by mass of solvent (methyl ethyl ketone), is applied to the back side (outer surface of the belt). ２ A spreading treatment was performed to apply the material, and tooth cloth precursor 8 was obtained.

[0317] The average thickness of the fluororesin-containing rubber layer (precursor) in tooth cloth precursor 8 was 55 μm.

[0318] In Example 18, 400 g / m of rubber adhesive, prepared by dissolving 40 parts by mass of rubber composition R1 in 100 parts by mass of solvent (methyl ethyl ketone), was applied to the surface side (inner circumference side of the belt) of the treated canvas. ２ After applying the spreading treatment, 100 g / m² of rubber adhesive, prepared by dissolving 25 parts by mass of rubber composition R6 in 100 parts by mass of solvent (methyl ethyl ketone), is applied to the back side (outer surface of the belt).２ A spreading treatment was performed to apply the material, and a tooth cloth precursor 9 was obtained.

[0319] The average thickness of the fluororesin-containing rubber layer (precursor) in tooth cloth precursor 9 was 75 μm.

[0320] (Comparative Examples 1-3) The woven fabrics shown in Table 5 were immersed in RFL treatment solution and rubber glue to produce tooth cloth precursors. Specifically, for the RFL treatment, two types of RFL treatment solutions (RFL1, RFL2) shown in Table 3 were used, and the immersion treatment was performed in the order of RFL1 followed by RFL2. Subsequently, for the rubber glue treatment, two types of rubber glues (rubber glue 1, rubber glue 2) shown in Table 4 were used, and the immersion treatment was performed in the order of rubber glue 1 followed by rubber glue 2 to obtain treated canvas.

[0321]

[0322] In Comparative Examples 1 and 3, a rubber adhesive prepared by dissolving 25 parts by mass of rubber composition R2 in 100 parts by mass of solvent (methyl ethyl ketone) was applied to the back side (outer belt side) of the treated canvas at a rate of 100 g / m². ２ A spreading treatment was performed to apply the material, and tooth cloth precursor 4 was obtained.

[0323] In Comparative Example 2, tooth cloth precursor 5 was obtained without performing the spreading treatment.

[0324] [Preparation of Uncrosslinked Rubber Sheets] To form the teeth and back (back rubber layer), each rubber composition shown in Table 1 was kneaded using a Banbury mixer, and the resulting kneaded rubber was rolled to a predetermined thickness using a calender roll to produce uncrosslinked rubber sheets. The short fibers contained in the uncrosslinked rubber sheets were oriented in the rolling direction.

[0325] [Manufacturing of Toothed Belts] In Examples 1 to 18 and Comparative Examples 1 to 6, toothed belts with a total thickness of 5.6 mm, tooth type G8M, tooth height (including tooth fabric) of 3.5 mm, tooth pitch of 8 mm, number of teeth of 140, circumference of 1120 mm, and width of 17 mm were manufactured using a pre-forming method as shown below.

[0326] In Examples 19 and 20, a toothed belt with a total thickness of 7.75 mm, tooth profile G11M, tooth height (including tooth cloth) of 4.75 mm, tooth pitch of 11 mm, number of teeth of 102, circumference of 1122 mm, and width of 17 mm was manufactured using a pre-forming method as shown below.

[0327] In Examples 20 and 21, a toothed belt with a total thickness of 9.6 mm, tooth profile G14M, tooth height (including tooth cloth) of 6.1 mm, tooth pitch of 14 mm, number of teeth of 80, circumference of 1120 mm, and width of 17 mm was manufactured using a pre-forming method as shown below.

[0328] Tables 7 to 11 show the tooth structure (layer structure) and the rubber composition used in each rubber layer of the toothed belts produced in each example and comparative example.

[0329] (Example 1) A press mold (flat type) having multiple grooves (recesses) corresponding to the teeth of a toothed belt was laminated in the following order: nylon film (nylon 6 unoriented film, "Rayfan" manufactured by Toray Film Processing Co., Ltd., thickness 50 μm), tooth cloth precursor 1 for forming the tooth cloth, and an uncrosslinked rubber sheet (R5, sheet thickness 1.70 mm) for forming the tooth rubber layer. The mold was then pressed for 160 seconds at a temperature of 90°C and a press pressure (surface pressure) of 20.2 MPa to produce a semi-crosslinked pre-molded body.

[0330] Furthermore, the tooth cloth precursor was laminated such that the side with the laminated rubber composition R1, which is a fluororesin-containing rubber layer precursor, faced the mold side (nylon film side).

[0331] Next, a pre-molded body was wrapped around a cylindrical mold having multiple grooves (recesses) corresponding to the teeth (fitting the teeth with the grooves of the cylindrical mold), and a twisted cord A for the core wire was spun spirally around the outer surface of the pre-molded body (tension: 150-250 N / string, spinning pitch: 1.10 mm, spinning speed: 1.5 m / s). Furthermore, an uncrosslinked rubber sheet (R2, sheet thickness 0.90 mm) that forms the back rubber layer was wrapped around the outer surface to form an uncrosslinked belt molded body (uncrosslinked laminate). The uncrosslinked rubber sheet was wrapped so that the orientation direction of the aramid short fibers contained in the sheet was in the longitudinal direction (circumferential direction) of the belt.

[0332] Next, using a vulcanizing vessel, cross-linking molding was performed for 40 minutes under conditions of a heating temperature of 180°C and a vapor pressure of 0.9 MPa to produce a cross-linked molded body (cross-linked belt sleeve).

[0333] Finally, a toothed belt with tooth profile G8 was obtained by cutting the bridging belt sleeve, which had been demolded from the cylindrical mold, to a width of 17 mm.

[0334] (Example 2) A toothed belt was manufactured in the same manner as in Example 1, except that tooth cloth precursor 1 was changed to tooth cloth precursor 2, and instead of an uncrosslinked rubber sheet forming the tooth rubber layer, an uncrosslinked rubber sheet forming the first rubber layer (R3, sheet thickness 0.70 mm) and an uncrosslinked rubber sheet forming the second rubber layer (R4, sheet thickness 1.00 mm) were laminated in this order.

[0335] (Comparative Example 1) A toothed belt was manufactured in the same manner as in Example 1, except that a nylon film was not used and tooth fabric precursor 1 was changed to tooth fabric precursor 4.

[0336] (Comparative Example 2) A toothed belt was manufactured in the same manner as in Example 2, except that a nylon film was not used and tooth fabric precursor 1 was changed to tooth fabric precursor 5.

[0337] (Comparative Example 3) A toothed belt was manufactured in the same manner as in Example 1, except that tooth fabric precursor 1 was changed to tooth fabric precursor 4.

[0338] (Comparative Example 4) A toothed belt was manufactured in the same manner as in Example 1, except that nylon film was not used.

[0339] (Comparative Example 5) A toothed belt was manufactured in the same manner as in Example 2, except that nylon film was not used.

[0340] (Comparative Example 6) A toothed belt was manufactured in the same manner as in Example 2, except that tooth fabric precursor 1 was changed to tooth fabric precursor 3.

[0341] (Examples 3-7) Toothed belts were manufactured in the same manner as in Example 1, except that the thickness of the resin film layer was changed to the thickness shown in Table 8.

[0342] (Examples 8-12) Toothed belts were manufactured in the same manner as in Example 2, except that the thickness of the resin film layer was changed to the thickness shown in Table 8.

[0343] (Example 13) A toothed belt was manufactured in the same manner as in Example 2, except that the nylon film was changed to a polypropylene film (Toray Industries, Inc.'s "Trefan," 50 μm thick).

[0344] (Example 14) A toothed belt was manufactured in the same manner as in Example 2, except that the nylon film was replaced with a polyurethane film ("Tough Grace" manufactured by Takeda Sangyo Co., Ltd., 50 μm thick).

[0345] (Examples 15-18) Toothed belts were manufactured in the same manner as in Example 2, except that tooth fabric precursor 2 was changed to tooth fabric precursors 6-9.

[0346] (Example 19) A toothed belt with tooth profile G11M was manufactured in the same manner as in Example 1, except that the thickness of the uncrosslinked rubber sheet forming the tooth rubber layer was changed to 2.75 mm, the thickness of the uncrosslinked rubber sheet forming the back rubber layer was changed to 1.35 mm, the core wire twisted cord A was changed to core wire twisted cord B, and the manufacturing conditions were changed to the conditions shown in Table 6.

[0347] (Example 20) A toothed belt with tooth profile G11M was manufactured in the same manner as in Example 2, except that the thickness of the uncrosslinked rubber sheet forming the first rubber layer was changed to 1.10 mm, the thickness of the uncrosslinked rubber sheet forming the second rubber layer was changed to 1.65 mm, the thickness of the uncrosslinked rubber sheet forming the back rubber layer was changed to 1.35 mm, the core wire twisted cord A was changed to core wire twisted cord B, and the manufacturing conditions were changed to the conditions shown in Table 6.

[0348] (Example 21) A toothed belt with tooth profile G14M was manufactured in the same manner as in Example 1, except that the thickness of the uncrosslinked rubber sheet forming the tooth rubber layer was changed to 3.10 mm, the thickness of the uncrosslinked rubber sheet forming the back rubber layer was changed to 1.50 mm, the core wire twisted cord A was changed to core wire twisted cord B, and the manufacturing conditions were changed to the conditions shown in Table 6.

[0349] (Example 22) A toothed belt with tooth profile G14M was manufactured in the same manner as in Example 2, except that the thickness of the uncrosslinked rubber sheet forming the first rubber layer was changed to 1.20 mm, the thickness of the uncrosslinked rubber sheet forming the second rubber layer was changed to 1.90 mm, the thickness of the uncrosslinked rubber sheet forming the back rubber layer was changed to 1.50 mm, the core wire twisted cord A was changed to core wire twisted cord B, and the manufacturing conditions were changed to the conditions shown in Table 6.

[0350] Table 6 shows the manufacturing conditions for toothed belts with tooth profiles G8M, G11M, and G14M.

[0351]

[0352] [Thickness of the resin film layer] The cross-section of the toothed belt, cut parallel to the belt width direction at the center of the belt length direction at the tooth root, was observed under a microscope at 20x magnification, and the average value of the resin film layer thickness (average value of 10 arbitrary points) was measured.

[0353] [Evaluation and Determination] For each test specimen (Examples 1 to 22 and Comparative Examples 1 to 6), a comparative verification was performed on jumping resistance, durability, and manufacturing cost to determine whether a toothed belt capable of solving the problem of the present invention was obtained.

[0354] (Method for evaluating jumping resistance) A belt was attached to the final deceleration side of a motorcycle, and plaster was applied to the entire circumference of the belt's tooth surface. After that, water was lightly sprayed on the plaster surface with a spray bottle to make it muddy. The motorcycle was then driven at full throttle, and the presence or absence of jumping was checked until the motorcycle came to a stop after 10 meters of driving with the brakes applied suddenly. The mounting tension of the belt was started at 500N, and if no jumping occurred, the mounting tension was gradually reduced, and the test was repeated until jumping occurred. Plaster application and water spraying were performed each time the mounting tension was changed. The lower the mounting tension at which jumping occurred, the better the jumping resistance of the toothed belt can be judged to be. Therefore, the reciprocal of the mounting tension at which jumping occurred can be used as an indicator of jumping resistance. In Tables 7 to 11, the relative values ​​are shown with the reciprocal of the mounting tension at which jumping occurred in Comparative Example 1 as the base (1.0), and the following criteria were used for judgment.

[0355] a. Jumping resistance of 2.5 or higher b. Jumping resistance of 1.5 or higher but less than 2.5 c. Jumping resistance of less than 1.5

[0356] (Method for evaluating durability) A toothed belt was attached to a two-axis running test machine equipped with a drive pulley (number of teeth: 24) and a driven pulley (number of teeth: 59), and the running time until failure (loss of teeth) occurred in the toothed belt was measured as the running life. The mounting tension of the toothed belt was 400 N, the rotational speed of the drive pulley was 917 rpm, the load on the driven pulley was 207 N·m, and the ambient temperature was 25°C (room temperature). In Tables 7 to 11, the running time until failure of Comparative Example 1 is expressed as a relative value with the reference (1.0), and was judged according to the following criteria.

[0357] a rating: Durability is 1.0 or higher c rating: Durability is less than 1.0

[0358] (Method for evaluating the surface condition of the tooth cloth) The surface condition of the tooth cloth was observed visually and judged according to the following criteria.

[0359] a) The entire surface of the tooth cloth is white and smooth. b) The entire surface of the tooth cloth is not uniform.

[0360] (Overall Assessment) Based on the assessment of each evaluation item, an overall assessment was made according to the following criteria.

[0361] A Rank: All evaluation items receive an 'a' rating. B Rank: At least one evaluation item receives a 'b' rating (no 'c' ratings). C Rank: At least one evaluation item receives a 'c' rating.

[0362] [Verification Results and Discussion] The verification results of the toothed belts obtained in the examples and comparative examples are shown in Tables 7 to 11.

[0363]

[0364]

[0365]

[0366]

[0367]

[0368] (Verification results in Table 7) In Comparative Examples 1 to 6, it was not possible to sufficiently improve jump resistance in any of them.

[0369] In particular, Comparative Examples 4-6, which used nylon canvas, showed lower durability than Comparative Example 1, which used PTFE canvas.

[0370] In Comparative Example 2, the tooth rubber layer has a two-layer structure, and PTFE canvas is used as the tooth fabric. Although it has high durability, it is not economically viable due to the use of PTFE canvas.

[0371] Furthermore, in Comparative Examples 3 and 6, although a resin film layer was laminated without laminating a fluororesin-containing rubber layer, it can be presumed that the unevenness of the weave could not be sufficiently filled, resulting in reduced smoothness, and that the resin film layer was prone to peeling, leading to poor interlocking and reduced durability.

[0372] Furthermore, in Comparative Examples 4 and 5, the surface of the nylon canvas was laminated with a fluororesin-containing rubber layer. However, the fluororesin-containing rubber layer alone was not sufficient to improve the smoothness of the tooth surface. As a result, mud adhered to the recesses, and more mud accumulated on top of the existing mud, which likely worsened the engagement between the belt and the pulley.

[0373] In contrast, in Example 1, while the extension of durability was small, the jumping resistance was significantly improved. Because PTFE canvas was not used, it was also more economical.

[0374] Furthermore, in Example 2, by using two layers of tooth rubber compared to Example 1, the jumping resistance was greatly improved, and durability was further enhanced.

[0375] Figure 6 shows a cross-sectional photograph (cross-sectional view in the belt width direction at the tooth root) of the toothed belt obtained in Example 2. In Figure 6, the dark semicircular area in the upper left is part of the core wire, and a woven fabric layer (tooth fabric), a fluororesin-containing rubber layer, and a resin film layer are formed below the core wire, and it can be seen that the white fluororesin-containing rubber layer penetrates deep into the woven fabric layer. The thickness of the woven fabric layer was the distance between the bottom of the woven fabric layer and the bottom of the core wire, and was 0.32 mm. The thickness of the resin film layer was 50 μm, and the thickness of the fluororesin-containing rubber layer was the distance between the resin film and the bottom of the woven fabric layer, and was 40 μm.

[0376] (Verification results in Table 8) In Examples 3 to 7, the thickness of the resin film layer was changed based on Example 1, and in Examples 8 to 12, the thickness of the resin film layer was changed based on Example 2. As a result, there was a tendency for jumping resistance to decrease as the thickness of the resin film layer increased, and a tendency for durability to decrease slightly as the resin film became thinner.

[0377] (Verification results in Table 9) In Examples 13 and 14, by changing the type of resin in the resin film layer based on Example 2, the polypropylene film and polyurethane film also showed jumping resistance and durability equivalent to that of the nylon film, indicating that the effect of the type of resin was small.

[0378] (Verification results in Table 10) In Examples 15 to 18, the thickness of the fluororesin-containing rubber layer was changed based on Example 2. As a result, there was a tendency for the jumping resistance to decrease in both cases, whether the thickness of the fluororesin-containing rubber layer was thinner or thicker than in Example 2.

[0379] As a result of evaluating the condition of the tooth fabric surface, in Examples 2, 16, and 17, the entire tooth fabric surface was white and smooth. Figure 7 shows a photograph of the tooth fabric surface of the toothed belt obtained in Example 2.

[0380] On the other hand, in Examples 15 and 18, the entire surface of the tooth cloth was not uniform.

[0381] Figure 8 shows a photograph of the tooth fabric surface of the toothed belt obtained in Example 15. In Example 15, where the fluororesin-containing rubber layer was thin, the entire tooth fabric was not covered with the fluororesin-containing rubber layer, resulting in a mottled pattern with areas covered and areas not covered by the fluororesin-containing rubber.

[0382] Figure 9 shows a photograph of the tooth surface of the toothed belt obtained in Example 18. In Example 18, where the fluororesin-containing rubber layer was thick, although the entire tooth surface was covered with the fluororesin-containing rubber layer, there were air bubbles that appeared to have formed when the solvent of the rubber adhesive evaporated, resulting in a low level of smoothness.

[0383] (Verification results in Table 11) In Examples 19 and 21, by significantly changing the tooth pitch based on Example 1, jumping resistance and durability were improved compared to Example 1. Also, in Examples 20 and 22, by significantly changing the tooth pitch based on Example 2, jumping resistance and durability were improved compared to Example 2.

[0384] The toothed belt (meshing transmission belt or toothed transmission belt) of the present invention can be used in combination with a toothed pulley in various fields where synchronization between input and output is required, such as power transmission mechanisms in vehicles such as automobiles and motorcycles, power transmission mechanisms in industrial machinery such as motors and pumps, machinery such as automatic doors and automated machines, OA equipment parts, coin handling equipment, photocopiers, and printing presses.

[0385] Furthermore, the toothed belt of the present invention can be used as a toothed belt for applications requiring a wide range of loads, from low loads to high loads (high horsepower), but it is particularly preferable to use it as a power transmission belt (timing belt or cogged belt) for industrial machinery and rear-wheel drive motorcycles that require high loads (high horsepower).

[0386] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-203183 filed on 21 November 2024 and Japanese Patent Application No. 2025-182319 filed on 29 October 2025, the contents of which are incorporated herein by reference.

[0387] 1...Toothed belt 1a...Tooth portion 1b...Tooth base portion 1c...Back portion 2...Laminate of tooth cloth, fluororesin-containing rubber layer, and resin film layer 2a...Tooth cloth 2b...Fluororesin-containing rubber layer 2c...Resin film layer 3...Tooth rubber layer 3a...First rubber layer 3b...Second rubber layer 4...Core wire 5...Back rubber layer

Claims

1. A toothed belt comprising: a back portion in which a core wire extending along the circumferential direction of the belt is embedded; a plurality of teeth formed on the inner circumferential surface of the back portion at intervals in the circumferential direction of the belt; a back rubber layer formed on the outer circumferential side of the belt with respect to the core wire; and a tooth rubber layer formed on the inner circumferential side of the belt with respect to the core wire; wherein a tooth cloth is laminated on the inner circumferential surface of the tooth rubber layer; a fluororesin-containing rubber layer formed from a crosslinked rubber composition containing fluororesin is laminated on the inner circumferential surface of the tooth cloth; and a resin film layer containing thermoplastic resin is laminated on the inner circumferential surface of the fluororesin-containing rubber layer.

2. The toothed belt according to claim 1, wherein the fluororesin is granular and has an average particle size of 1 to 100 μm.

3. The toothed belt according to claim 1 or 2, wherein the average thickness of the fluororesin-containing rubber layer is 10 to 100 μm.

4. The toothed belt according to any one of claims 1 to 3, wherein the average thickness of the resin film layer is 20 to 120 μm.

5. The toothed belt according to any one of claims 1 to 4, wherein the melting point of the thermoplastic resin is 100 to 250°C.

6. The toothed belt according to any one of claims 1 to 5, wherein the thermoplastic resin comprises at least one selected from the group consisting of polyolefin resins, polyamide resins, and polyurethane resins.

7. The toothed belt according to any one of claims 1 to 6, wherein the tooth fabric does not contain fluorine-based fibers.

8. The toothed belt according to any one of claims 1 to 7, wherein the toothed fabric is a single-weave woven fabric.

9. The toothed belt according to any one of claims 1 to 8, wherein the core wire is a twisted cord of carbon fiber.

10. The toothed belt according to any one of claims 1 to 9, wherein the toothed rubber layer is formed by a first rubber layer on the inner circumference of the belt and a second rubber layer on the outer circumference of the belt, and the modulus of elasticity of the first rubber layer is greater than the modulus of elasticity of the second rubber layer.

11. A toothed belt transmission mechanism comprising a toothed belt according to any one of claims 1 to 10 and a pulley.

12. The toothed belt transmission mechanism according to claim 11, used for transmission applications in rear-wheel drive of motorcycles.

13. A method for manufacturing a toothed belt according to any one of claims 1 to 10, comprising a pre-molding step of producing a pre-molded body in which a first precursor for forming a resin film layer, a second precursor for forming a fluororesin-containing rubber layer, a third precursor for forming a tooth cloth, and a fourth precursor for forming a tooth rubber layer are laminated together.

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