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

Abstract

We provide toothed belts with high durability and jump resistance. [Solution] The back portion 1c has a core wire 4 embedded in it that extends along the circumferential direction of the belt, The inner circumferential surface of the back portion 1c is provided with a plurality of teeth 1a formed at intervals in the belt circumferential direction, It includes a back rubber layer 5 formed on the outer circumference side of the belt relative to the core wire 4, and a tooth rubber layer 3 formed on the inner circumference side of the belt relative to the core wire 4, In a toothed belt 1 in which a tooth cloth is laminated on the inner circumferential surface of the tooth rubber layer 3, 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 a thermoplastic resin is laminated on the inner circumferential surface of the fluororesin-containing rubber layer.

Description

[Technical Field]

[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. [Background technology]

[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, 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 friction coefficient 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 applied to the surface of the teeth. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 2023-16001 [Patent Document 2] Japanese Patent Publication No. 2024-128945 [Patent Document 3] Japanese Patent Publication No. 2000-310293 [Patent Document 4] Japanese Patent Publication No. 2002-103467 [Patent Document 5] Japanese Patent Publication No. 2006-17264 [Patent Document 6] Japanese Patent Publication No. 2006-84010

Summary of the Invention

Problems to be Solved by the Invention

[0014] However, in the toothed belts of Patent Documents 3 to 6, although the effect of reducing the friction coefficient of the tooth portion is high in the initial stage of belt use, fluororesin or a rubber composition containing fluororesin is likely to scatter, and it has been difficult to reduce the friction coefficient of the tooth portion over a long period or to improve the wear resistance. Further, when a rubber composition containing fluororesin is applied to the tooth cloth, there is also a problem that it is difficult to improve the smoothness of the tooth surface. When the smoothness of the tooth surface is low, mud is likely to adhere to the concave portions, and further mud accumulates on the adhered mud, deteriorating the engagement between the belt and the pulley, and reducing the durability and anti-jumping property. Also, in the tooth cloth woven with PTFE fibers used in Patent Document 2, for example, when a double-woven canvas of PTFE fibers is used, mud is likely to accumulate in the weave of the canvas, and the same phenomenon occurs. Further, the inventors of the present invention also considered completely filling and smoothing the weave of the canvas with a rubber composition containing fluororesin, but it was difficult to completely fill and smooth the weave.

[0015] Therefore, an object of the present invention is to provide a toothed belt having high durability and anti-jumping property, 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 capable of improving durability and anti-jumping property without using a special tooth cloth, a toothed belt transmission mechanism using the same, and a method for manufacturing a toothed belt.

[0017] Still another object of the present invention is to provide a toothed belt that can be manufactured at a low cost and has excellent durability and anti-jumping property, a toothed belt transmission mechanism using the same, and a method for manufacturing a toothed belt.

Means for Solving the Problems

[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 back portion in which a core wire extending along the circumferential direction of the belt is embedded, The inner circumferential surface of the back portion is provided with a plurality of teeth formed at intervals in the circumferential direction of the belt, It includes a back rubber layer formed on the outer circumference side of the belt relative to the core wire, and a tooth rubber layer formed on the inner circumference side of the belt relative to the core wire, A toothed belt in which tooth cloth is laminated on the inner 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, A toothed belt having a resin film layer containing a thermoplastic resin laminated on the inner circumferential surface of the aforementioned 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 of Embodiments [1] to [3], wherein the average thickness of the resin film layer is 20 to 120 μm.

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

[0025] Embodiment [6]: A 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 of Embodiments [1] to [6], wherein the tooth fabric does not contain fluorine-based fibers.

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

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

[0029] Embodiment

[10] : A toothed belt according to any of Embodiments [1] to [9], wherein the toothed rubber layer is formed of 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.

[0030] Embodiment

[11] : A toothed belt transmission mechanism comprising a toothed belt according to any of Embodiments [1] to

[10] and a pulley.

[0031] Embodiment

[12] : The toothed belt transmission mechanism according to Embodiment

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

[0032] Embodiment

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

[10] , comprising a premolding step of producing a premolded 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.

[0033] In this application, the numerical range represented by "A~B" means "A or greater and B or less," and is used to include the values ​​A and B at both ends of that range.

[0034] Furthermore, in this application, "inner circumferential surface" refers to the "inner circumferential surface of the belt" in each layer. [Effects of the Invention]

[0035] In this invention, a toothed belt in which the inner circumferential surface of the tooth rubber layer is covered with a tooth fabric, is provided with a toothed belt that has high durability and jumping resistance because the inner circumferential surface of the tooth fabric is sequentially laminated with a fluororesin-containing rubber layer and a resin film layer. In particular, since the durability and jumping resistance of the toothed belt can be improved without using special tooth fabrics (for example, tooth fabrics containing fluororesin fibers or tooth fabrics with a multi-layered weave structure), it is also economically advantageous. [Brief explanation of the drawing]

[0036] [Figure 1] Figure 1 is a schematic partial cross-sectional perspective view showing an example of a toothed belt according to the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view of the toothed belt shown in Figure 1. [Figure 3] Figure 3 is a partially enlarged view showing details of the inner surface of the toothed belt in Figure 1. [Figure 4] 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] Figure 5 is a schematic cross-sectional view showing another example of the toothed belt of the present invention. [Figure 6] Figure 6 is a cross-sectional photograph of the toothed belt obtained in Example 2. [Figure 7] Figure 7 is a photograph of the toothed surface of the toothed belt obtained in Example 2. [Figure 8] Figure 8 is a photograph of the tooth surface of the toothed belt obtained in Example 15. [Figure 9] Figure 9 is a photograph of the toothed surface of the toothed belt obtained in Example 18. [Modes for carrying out the invention]

[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, identical or functionally common elements (or components) may be denoted by the same reference numeral.

[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. The belt surface (inner circumferential surface) on the tooth 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 constituting the surface of the tooth portion is a constituent element of the tooth portion, while the laminate 2 constituting the surface of the tooth root portion is a constituent element of the back portion. Furthermore, each laminate 2 constituting the tooth portion is part of a continuous laminate 2 (part of 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 tooth portion 1a with a substantially trapezoidal cross-section has a circumferential surface formed by the laminate 2, and its interior is formed by 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), the rotation of the drive pulley transmits power from the drive pulley side to the driven pulley side.

[0051] The toothed belt of the present invention is not limited to the form and structure 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 roughly trapezoidal shape, but may be, for example, semicircular, semielliptical, polygonal [triangle, quadrilateral (rectangle, trapezoid, etc.)], etc. Of these, a trapezoidal or roughly 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, as this can improve 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 surface of the belt [the average value of the thickness (distance or height) from the tooth root surface to the tooth apex].

[0059] [Dental Department] 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 and other factors, 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 structure of 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 at 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 in contact with the core wire, i.e., a substantially trapezoidal shape formed between the first rubber layer and the core wire, and a substantially trapezoidal shape formed between the other rubber layer and the core wire are 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 the hardness 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 on the Type D hardness scale, preferably 53 to 65, more preferably 54 to 62, even more preferably 55 to 60, and most preferably 56 to 59. 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, 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.

[0071] (1A) First rubber component Examples of rubber components (first rubber components) of the first crosslinked rubber composition forming the first rubber layer include diene rubbers [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 elastomers (ethylene-propylene copolymer (EPM), ethylene-propylene-diene ternary copolymer (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 and carboxylated NBR. These rubber components can be used individually or in combination of two or more types.

[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, especially 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 80-100% 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 50-100%, and may be 70-100%.

[0073] In this application, HNBR refers to a rubber that maintains the oil resistance, which is an 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, 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 includes a composite polymer containing hydrogenated nitrile rubber and an unsaturated metal carboxylate salt (hereinafter referred to as "HNBR / unsaturated metal carboxylate composite polymer"). 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] Preferred unsaturated carboxylate metal salts include zinc (meth)acrylate and magnesium (meth)acrylate. Unsaturated carboxylate metal salts can be used alone 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 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 system compounding agent The first crosslinked rubber composition may further contain a first filler compound. Examples of the first filler compound include a first filler and first short fibers.

[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 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 that 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 first staple 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 (e.g., 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 preferred, and aliphatic polyamide fibers being the most preferred.

[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 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 filler 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 cross-linking 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), and a first crosslinking retarder (vulcanization retarder). 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-di-methyl-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 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 tetraacrylate, etc.]. Examples include alkane polyol poly(meth)acrylates such as tra(meth)acrylate, 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 co-crosslinking 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 modulus of elasticity can be improved by adding a co-crosslinking 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) 1 Other Combination Agent The first crosslinked rubber composition may further contain conventional additives used in rubber compositions for toothed belts. Conventional 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.), and plasticizers [aliphatic carboxylic acid plasticizers (adipate ester plasticizers, sebacate ester plasticizers, etc.), aromatic carboxylic acid ester plasticizers]. Examples of additives include phthalate ester plasticizers, trimellitic acid ester plasticizers, oxycarboxylic acid ester plasticizers, phosphate ester plasticizers, ether plasticizers, ether ester plasticizers, etc., antioxidants (oxidants, heat aging inhibitors, flex crack inhibitors, ozone degradation inhibitors, etc.), colorants, adhesion improvers, tackifiers, plasticizers, coupling agents (silane coupling agents, etc.), stabilizers (UV 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 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 the crosslinking compounding agent, short fibers, and filler.

[0128] (2A) Second rubber component The second rubber component of the second crosslinked rubber composition forming 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 system compounding agent The second crosslinked rubber composition may further contain a second filler compound. Examples of the second filler compound include a second filler and second short fibers.

[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 second crosslinking compounds 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), and a second crosslinking retarder (vulcanization retarder). 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 cocrosslinking agent can be selected from the cocrosslinking agents exemplified as the first cocrosslinking agent, including preferred embodiments.

[0145] The proportion of the second cocrosslinking 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 Combination Agent The second crosslinked rubber composition may further contain, as other compounding agents (second other compounding agents), conventional additives used in rubber compositions for toothed belts. These conventional additives can be selected from those exemplified as the first other compounding agents.

[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 structure of 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 on the Type D hardness scale, preferably 53 to 75, more preferably 55 to 70, even more preferably 60 to 65, and most preferably 62 to 64. 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 system compounding agent The third crosslinked rubber composition may further contain a third filler compound. Examples of the third filler compound include a third filler and third short fibers.

[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 for 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 average particle size range 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 staple fiber can be selected from the staple fibers exemplified as the second staple 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 cross-linking 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 cocrosslinking agent can be selected from the cocrosslinking agents exemplified as the first cocrosslinking 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 Combination Agent The third crosslinked rubber composition may further contain, as other compounding agents (third other compounding agents), conventional additives used in rubber compositions for toothed belts. These conventional additives can be selected from those exemplified as the first other compounding agents.

[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 the tooth portion, an adhesive rubber layer may be interposed between the tooth rubber layer and the tooth cloth to improve adhesion 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) Fourth rubber component The fourth rubber component of the fourth crosslinked rubber composition forming 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 Improvement Agent The fourth crosslinked rubber composition may contain a fourth adhesion improver, as it can improve adhesion to the tooth cloth and tooth rubber layer.

[0182] Examples of the fourth adhesion improver 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 improvers 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 cross-linking 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 combination 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 dioxide 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 cloth) The tooth fabric laminated on the inner surface of the tooth rubber layer may be made of, for example, woven fabric, knitted fabric, or nonwoven fabric. Conventionally, it is often woven fabric (canvas), and is composed 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 fabric 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.] 2-4Alkilen 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, 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 (such as PET fibers), polyamide fibers (such as aliphatic polyamide fibers like polyamide 66 fibers, aramid fibers, etc.), PBO fibers, and fluororesin fibers [such as polytetrafluoroethylene (PTFE) fibers] 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, elastic polyurethane elastic yarns such as spandex made of polyurethane, and 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; or dissolving a rubber composition in an organic solvent to make a rubber glue, immersing the fabric in this 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 an RFL treatment solution, the fabric may be further immersed in 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 adhesion may decrease.

[0206] The basis weight of the fluororesin-containing rubber layer is, for example, 100 to 350 g / m². 2 Preferably 150-250 g / m² 2 More preferably 180-220 g / m² 2If 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) Fluororesin 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 fluororesin shapes 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 the 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 Improvement Agent The fifth crosslinked rubber composition may contain a fifth adhesion improver, as it can improve adhesion to the tooth cloth and 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 cross-linking 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 co-crosslinking agent, a fifth crosslinking aid (vulcanization aid), a fifth crosslinking accelerator (vulcanization accelerator), and a fifth crosslinking retarder (vulcanization retarder). Of these, the fifth crosslinking compound preferably contains at least a fifth crosslinking agent and a fifth co-crosslinking agent (crosslinking aid), and a combination of a fifth crosslinking agent and a fifth co-crosslinking agent is particularly preferred.

[0225] The fifth crosslinking agent can be selected from the crosslinking agents exemplified as the first crosslinking agent. Of these 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. Of the aforementioned 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) 5 Other combination agents 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 dioxide 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 this 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; tertiary copolymers 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 approximately 100 to 250°C. For polypropylene resins, it is preferably 130 to 180°C, more preferably 140 to 170°C, and for 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 increased 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 portion, as well as the surface on the tooth side of the back portion (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, 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 (back of the belt) on the side where the teeth are not formed 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 a Type A hardness of, for example, 60 to 95, preferably 70 to 93, more preferably 75 to 90, 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 forming 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) Rubber component 6 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 addition, for 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) 6th 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 average particle size and iodine adsorption amount of carbon black in the sixth 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.

[0259] The proportion of carbon black may be, for example, 100 parts by mass or less per 100 parts by mass of the sixth 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).

[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 manufacturing 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 preferable, and hydrous silicic acid having a large number of surface silanol groups has a strong chemical bonding force with the rubber component.

[0261] The average particle diameter (average primary particle diameter) 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 with respect to 100 parts by mass of the sixth rubber component, 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.

[0264] The proportion of the sixth filler may be, for example, 100 parts by mass or less with respect to 100 parts by mass of the sixth rubber component, 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.

[0265] (6C) The sixth crosslinking system compounding agent The sixth crosslinked rubber composition may further contain sixth crosslinking compounding agents. Examples of sixth crosslinking compounding agents include sixth crosslinking agents (vulcanizing agents) for crosslinking the sixth rubber components, as well as sixth co-crosslinking agents, sixth crosslinking aids (vulcanization aids), sixth crosslinking accelerators (vulcanization accelerators), and sixth crosslinking retarders (vulcanization retarders). Of these, the sixth crosslinking compounding agent 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 cocrosslinking agent can be selected from the cocrosslinking agents exemplified as the first cocrosslinking agent, including preferred embodiments.

[0270] The proportion of the sixth cocrosslinking 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) 6. Other combination agents The sixth crosslinked rubber composition may further contain other compounding agents (sixth other compounding agent), such as sixth short fibers and conventional additives used in rubber compositions for toothed belts. The sixth short fibers can be selected from the short fibers exemplified as the first short fibers. The conventional additives can be selected from the additives exemplified as the first other compounding agent.

[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] [Heart wire] On the back of the belt, a core wire extending along the belt circumferential direction is embedded on the inner circumference side of the back rubber layer. This core wire acts as a tensile body, improving the running stability and strength of the toothed belt. Furthermore, on the back, the core wire, which is usually a twisted cord extending along the belt circumferential direction, is 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 wire 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 involving particularly high loads, 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 the multifilament yarn of carbon fiber is greater than 1000 tex, the flexural fatigue resistance may decrease. Conversely, if the fineness of the multifilament yarn of carbon fiber is less than 300 tex, the material cost increases, and the number of twisted yarns required to produce a core wire with sufficient tensile strength increases, resulting in an increase in the working hours.

[0283] In one embodiment of the toothed belt of the present invention, a carbon fiber cord (12K-1 / 0) obtained by single-twisting one 12K multifilament yarn (fineness is about 800 tex) is used as the core wire. Alternatively, one 12K multifilament yarn (fineness is about 800 tex) may be down-twisted to produce a down-twisted yarn, and four of the produced down-twisted yarns may be combined and up-twisted to use a lang lay carbon fiber cord (12K-1 / 4) as the core wire. Note that "12K-1 / 0" represents a twisted cord obtained by single-twisting one 12K multifilament yarn, and "12K-1 / 4" represents a twisted cord obtained by down-twisting one 12K multifilament yarn to produce a down-twisted yarn and then combining and up-twisting four of the produced down-twisted yarns. Similarly, for example, "12K-1 / 3" represents a twisted cord obtained by down-twisting one 12K multifilament yarn to produce a down-twisted yarn and then combining and up-twisting three of the produced down-twisted yarns, and "12K-4 / 0" represents a twisted cord obtained by single-twisting four 12K multifilament yarns together.

[0284] The core wire may be subjected to an adhesion treatment in order to enhance the adhesion to the crosslinked rubber composition. As a method of the adhesion treatment, for example, a method of immersing the twisted cord in a resorcinol-formalin-latex treatment liquid (RFL treatment liquid) and then heating and drying to form a uniform adhesion layer on the surface of the twisted cord may be used. The RFL treatment liquid is a mixture obtained by mixing an initial condensate of resorcinol and formalin with latex, and the latex may be, for example, chloroprene rubber, styrene-butadiene-vinylpyridine terpolymer (VP latex), nitrile rubber, hydrogenated nitrile rubber, or the like. Further, the adhesion treatment method may be a method of performing a pretreatment with an epoxy compound or an isocyanate compound and then treating with the RFL treatment liquid.

[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 toothed belts> 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 tooth rubber layer precursor and back rubber layer precursor preparation process, 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] [Preparation process for tooth cloth precursor] In the tooth cloth precursor preparation step, a tooth cloth precursor is prepared to form the tooth cloth. Specifically, in the tooth cloth precursor preparation step, the tooth cloth precursor is prepared by laminating a fluororesin-containing rubber layer onto the inner surface of the tooth cloth. 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 tooth cloth (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 tooth cloth that has been bonded may be used, and if an adhesive rubber layer is to be formed between the tooth cloth and the tooth rubber layer, the adhesive rubber layer may be formed on the outer surface of the tooth cloth 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 multiple 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 70-90°C) at which the rubber composition softens, and pressure is applied 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] Alternatively, instead of using a cylindrical mold, a flat press mold (flat mold) having multiple grooves (recesses) corresponding to the teeth may be used to form the teeth by press-fitting the rubber composition of the uncrosslinked rubber sheet and the tooth fabric precursor into the grooves (recesses) of the flat mold using the above procedure. In this method, after demolding the preform from the flat mold, the preform is wrapped around and attached to a cylindrical mold having multiple grooves (recesses) corresponding to the teeth (fitting the teeth and grooves), and the process moves to the next step.

[0294] [Crosslinking molding process] The twisted 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 can. 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. [Examples]

[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 compositions that form the fluororesin-containing rubber layer, adhesive rubber layer, tooth rubber layer, and back rubber layer.

[0299] [Table 1]

[0300] [Materials for rubber compositions] HNBR: Zetpol2010, manufactured by Nippon Zeon Co., Ltd., iodine value 11mg / 100mg HNBR containing unsaturated metal carboxylate: Zeon Corporation's "Zeoforte ZSC2295CX," base HNBR:unsaturated metal carboxylate (mass ratio) = 100:110, iodine value of base HNBR 28 mg / 100 mg Nylon staple fibers: Polyamide 66, manufactured by Asahi Kasei Corporation ("Leona"), average fiber length 3 mm, average fiber diameter 27 μm Aramid short fibers: "Conex" manufactured by Teijin Limited, average fiber length 3 mm, average fiber diameter 14 μm Stearic acid: "Stearic acid Tsubaki" manufactured by NOF Corporation. Carbon black SRF: "Seas S" manufactured by Tokai Carbon Co., Ltd., average particle size 66 nm, iodine adsorption capacity 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: "Zinc Oxide Type 2" manufactured by Sakai Chemical Industry Co., Ltd., average particle size 0.55 μm Plasticizer: ADEKA Corporation's "ADEKA Sizer RS700" Anti-aging agent: p,p'-dioctyldiphenylamine, manufactured by Seiko Chemical Co., Ltd. ("Nonflex OD3") Organic peroxide: 1,3-bis(t-butylperoxyisopropyl)benzene, theoretical reactive oxygen species content 9.45% Co-crosslinking agent 1: N,N'-m-phenylenedimaleimide, manufactured by Ouchi Shinko Chemical Co., Ltd., "Balnock PM" Co-crosslinking agent 2: Zinc methacrylate, manufactured by Asada Chemical Industries, Ltd., "R-20S" Titanium dioxide: COTIOX KA-100 manufactured by Cosmo Chemical Co., Ltd. Phenolic resin: Sumitomo Bakelite Co., Ltd. "RP-12687" Sulfur: "MIDAS" manufactured by Migen Chemical Co., Ltd. Fluororesin: Low molecular weight PTFE, manufactured by Mitsui Chemours Fluoroproducts Co., Ltd., "MP-1300-J", average particle size 11 μm

[0301] [Rubber hardness of cross-linked 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 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 wires] (Twisted cord A) A carbon fiber cord (12K-1 / 0, tensile modulus 230 GPa) was prepared by twisting one strand of 12K multifilament yarn [Toray Industries, Inc. "Torayca T700SC-12000", single filament 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 core wire twisted cord A with a wire diameter of 1.0 mm.

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

[0304] [Tooth cloth and tooth cloth processing] (Examples 1-22 and Comparative Examples 4-6) The woven fabrics shown in Table 2 were immersed in RFL treatment solution and rubber glue to produce tooth cloth precursors. Specifically, the RFL treatment was performed using two types of RFL treatment solutions (RFL1 and RFL2) shown in Table 3, with immersion treatment carried out in the order of RFL1 followed by RFL2. Subsequently, the rubber glue treatment was also performed using two types of rubber glue (rubber glue 1 and rubber glue 2) shown in Table 4, with immersion treatment carried out in the order of rubber glue 1 followed by rubber glue 2 to obtain treated canvas.

[0305] [Table 2]

[0306] [Table 3]

[0307] [Table 4]

[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 circumferential 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 circumferential 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, a 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 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 3 was obtained.

[0312] In Example 15, 100 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 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 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 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 / 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 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 / 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 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, the RFL treatment was performed using two types of RFL treatment solutions (RFL1 and RFL2) shown in Table 3, with immersion treatment in the order of RFL1 followed by RFL2. Subsequently, the rubber glue treatment was also performed using two types of rubber glue (rubber glue 1 and rubber glue 2) shown in Table 4, with immersion treatment in the order of rubber glue 1 followed by rubber glue 2 to obtain treated canvas.

[0321] [Table 5]

[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. 2A 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] For forming 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 an uncrosslinked rubber sheet. The short fibers contained in the uncrosslinked rubber sheet were oriented in the rolling direction.

[0325] [Manufacturing of toothed belts] In Examples 1-18 and Comparative Examples 1-6, toothed belts with a total thickness of 5.6 mm, tooth profile G8M, tooth height (including tooth cloth) 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, toothed belts 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 were 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 rubber composition R1, which is a fluororesin-containing rubber layer precursor, was 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 was 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 the 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 fabricated in the same manner as in Example 1, except that nylon film was not used and tooth fabric precursor 1 was replaced with tooth fabric precursor 4.

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

[0337] (Comparative Example 3) A toothed belt was fabricated 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 fabricated 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) A toothed belt was 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) A toothed belt was 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 replaced with 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) A toothed belt was fabricated 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 stranded cord A for the core wire was changed to stranded cord B for the core wire, 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 stranded cord A was changed to core wire stranded 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 stranded cord A was changed to core wire stranded 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] [Table 6]

[0352] [Thickness of the resin film layer] The cross-section of a 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 thickness of the resin film layer (average of any 10 points) was measured.

[0353] [Evaluation and Judgment] For each test specimen (Examples 1-22 and Comparative Examples 1-6), 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 jump 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 traveling 10 meters and applying the brakes 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. 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 rating: Jump resistance of 2.5 or higher Grade B: Jump resistance is between 1.5 and 2.5. C rating: Jump resistance is 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 400N, the rotation speed of the drive pulley was 917rpm, the load on the driven pulley was 207N·m, and the ambient temperature was 25℃ (room temperature). In Tables 7 to 11, the running time until failure in Comparative Example 1 is expressed as a relative value with the baseline (1.0), and the following criteria were used for evaluation.

[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 tooth cloth) The condition of the tooth cloth surface was observed visually and judged according to the following criteria.

[0359] Grade A: The entire surface of the tooth cloth is white and smooth. Grade B: The entire surface of the dental cloth is not uniform.

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

[0361] A Rank: All evaluation items receive an A rating. Rank B: At least one of the evaluation items receives a "b" rating (no "c" ratings). C rank: One of the evaluation items has a C rating.

[0362] [Verification Results and Discussion] Tables 7-11 show the verification results of the toothed belts obtained in the examples and comparative examples.

[0363] [Table 7]

[0364] [Table 8]

[0365] [Table 9]

[0366] [Table 10]

[0367] [Table 11]

[0368] (Verification results in Table 7) In Comparative Examples 1-6, the jumping resistance could not be sufficiently improved in any of the cases.

[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. While this provides high durability, the use of PTFE canvas results in low cost-effectiveness.

[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 insufficient 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 3-7, the thickness of the resin film layer was changed based on Example 1, and in Examples 8-12, 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 slight decrease in durability as the thickness of the resin film decreased.

[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 15-18, 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] Evaluation of the tooth fabric surface revealed that 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, the tooth pitch was significantly modified based on Example 1, resulting in improved jumping resistance and durability compared to Example 1. Similarly, in Examples 20 and 22, the tooth pitch was significantly modified based on Example 2, resulting in improved jumping resistance and durability compared to Example 2. [Industrial applicability]

[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 such as motors and pumps in industrial machinery, machinery such as automatic doors and automated machines, office automation equipment parts, coin handling equipment, photocopiers, and printers.

[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). [Explanation of Symbols]

[0386] 1…Toothed belt 1a...teeth part 1b...Root of the tooth 1c...back 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. The back portion has a core wire embedded in it that extends along the circumference of the belt, The inner circumferential surface of the back portion is provided with a plurality of teeth formed at intervals in the circumferential direction of the belt, It includes a back rubber layer formed on the outer circumference side of the belt relative to the core wire, and a tooth rubber layer formed on the inner circumference side of the belt relative to the core wire, A toothed belt in which tooth cloth is laminated on the inner 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, A toothed belt having a resin film layer containing a thermoplastic resin laminated on the inner circumferential surface of the aforementioned 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 woven fabric with a single-layer structure.

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

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. A toothed belt transmission mechanism according to claim 11, used for power transmission in the rear-wheel drive of a motorcycle.

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.

Images