Wrapped bonded V-belt and method for manufacturing the same

Abstract

This invention provides a wrapped V-belt that improves the adhesive strength between the wrapped V-belt section and the tie band, while also offering excellent resistance to lateral pressure. [Solution] The wrapped bonded V-belt includes a belt body comprising a plurality of wrapped V-belt sections covered with an outer covering, and tie bands connecting the plurality of wrapped V-belt sections on the outer circumferential surfaces of each wrapped V-belt section, wherein the belt body comprises a core layer including a core body, at least one stretchable rubber layer laminated on the outer circumferential side of the core layer, and a compression rubber layer laminated on the inner circumferential side of the core layer, wherein the outer circumferential surface of the wrapped V-belt section is not covered with the outer covering, and the stretchable rubber layer is exposed. The exposed stretchable rubber layer is formed from a crosslinked rubber composition containing rubber components and carbon black, and the proportion of carbon black is adjusted to 20 to 80 parts by mass per 100 parts by mass of the rubber components.

Description

[Technical Field]

[0001] The present invention relates to a wrapped V-belt in which multiple wrapped V-belt sections are connected in the width direction, and to a method for manufacturing the same. [Background technology]

[0002] Friction transmission belts such as V-belts, V-ribbed belts, and flat belts are known as power transmission belts. V-belts include raw-edge type (raw-edge V-belts), in which the friction transmission surface (V-shaped side) is an exposed rubber layer, and wrapped type (wrapped V-belts), in which the friction transmission surface is covered with an outer sheath. These V-belts are widely used in general industrial machinery and agricultural machinery.

[0003] In agricultural machinery and other applications, wrapped V-belts are used, in which the entire belt surface, including the friction transmission surface, is covered with an outer sheath (cover cloth) around its circumference. This is because using a raw-edge V-belt, which is a rubber layer with an exposed friction transmission surface, can lead to a high coefficient of friction on the transmission surface, increasing stress on the belt and potentially causing premature breakage. Furthermore, if the belt becomes entangled with straw, stones, wood, etc., the sudden impact on the transmission surface can damage the belt and the entire transmission mechanism. By using a wrapped V-belt, the coefficient of friction on the transmission surface is reduced, allowing for moderate slippage and mitigating stress and impact on the belt. Additionally, the transmission surface is protected and less prone to damage.

[0004] Large agricultural machinery used on large farms in Europe and America requires the transmission of enormous amounts of power, necessitating the use of multiple V-belts simultaneously. In other words, multiple V-belts must be wrapped around the pulleys of the belt drive mechanism in parallel (multiple belts) and rotated. When multiple V-belts are used, tension differences can occur between the parallel V-belts, potentially impairing stable power transmission. Furthermore, contact between adjacent V-belts can cause the inner and outer circumferences of the belts to reverse, resulting in an inverted structure (overturning).

[0005] Therefore, when multiple V-belts are to be driven in parallel, a combined belt (combined V-belt) is used, which is composed of multiple annular V-belt sections having the same structure as a V-belt, connected in the belt width direction. In this combined V-belt, multiple V-belt sections are arranged in parallel and connected or joined by tie bands (connecting members such as cloth). In some cases, a wrapped V-belt (wrapped V-belt section) covered with an outer cloth (cover cloth) is used as the V-belt section. A typical wrapped combined V-belt in which such wrapped V-belt sections are connected by tie bands (connecting members) is shown in a schematic partial cross-sectional perspective view in Figure 1.

[0006] As shown in Figure 1, the wrapped V-belt 100 comprises two wrapped V-belts (wrapped V-belt sections) 101 arranged parallel to each other at a distance, and the two wrapped V-belts 101 are connected by connecting members (tie bands) 102 made of fabric on their respective outer surfaces. Each wrapped V-belt 101 is formed of an endless belt body (belt body section) consisting of an expandable rubber layer 104 on the outer circumference of the belt, a compressible rubber layer 103 on the inner circumference of the belt, and a core body 105 embedded between the expandable rubber layer 104 and the compressible rubber layer 103 along the longitudinal direction of the belt (circumferential direction, direction A in the figure), and an outer covering fabric 106 (woven fabric, knitted fabric, nonwoven fabric, etc.) that covers the periphery of this belt body over the entire length in the circumferential direction of the belt. In this example, the core 105 consists of strands of wire (twisted cord) arranged at predetermined intervals in the belt width direction (direction B in the figure), and is interposed between the stretchable rubber layer 104 and the compressed rubber layer 103, in contact with both layers.

[0007] More specifically, a wrapped V-belt disclosed in Japanese Patent Publication No. 47-34432 (Patent Document 1) can be cited. Figure 2 shows a schematic partial cross-sectional view (a cross-sectional view perpendicular to the belt length direction) of a conventional wrapped V-belt such as the one disclosed in Patent Document 1.

[0008] In the conventional wrapped V-belt 111 shown in Figure 2, multiple (two in the figure) wrapped V-belt sections V are connected by tie bands (connecting members) T, and are arranged in parallel at intervals in the belt width direction (direction B in Figure 1). Each wrapped V-belt section V has a laminated structure in which a compression rubber layer 112, a core body 113, and an expandable rubber layer 114 are stacked in that order from the inner circumference to the outer circumference of the belt. It consists of an endless belt body with an inverted trapezoidal cross-section extending in the belt length direction (circumferential direction, direction A in Figure 1) and an outer cover cloth 115 that covers the periphery of this belt body. This outer cover cloth 115 is made of a continuous piece of fabric and covers the entire surface of the belt body (inner circumference, both sides, and outer circumference). The outer cover cloth 115 is overlapped on the inner circumference side to form a two-layer structure.

[0009] However, conventional wrapped V-belts 111 have a problem in that the wrapped V-belt portion V and the tie band T are prone to delamination. Specifically, the entire surface of the wrapped V-belt portion V is covered with an outer covering 115, and it is bonded or connected to the tie band T via the outer covering 115a covering the outer circumferential surface. In particular, when the tie band T is made of cloth, the bonding is between the cloths, making it difficult to bond or connect with high adhesive strength. Furthermore, while it is rare for foreign objects to get caught between the belt and pulley in general industrial machinery, in agricultural machinery, foreign objects such as rice husks are prone to getting caught between the belt and pulley. When foreign objects get caught, the slip ratio increases and the temperature rises, which reduces the adhesive strength between the wrapped V-belt portion V and the tie band T, making the tie band T prone to delamination. Furthermore, the wrapped V-belt section V is required to have high lateral pressure resistance. If the lateral pressure resistance is low, the belt will deform and sag towards the inner circumference of the pulley will increase, making it easier for the tie band T to peel off.

[0010] As a countermeasure, attempts have been made to improve the adhesion between the wrapped V-belt and the tie band by exposing the rubber layer from the outer surface (back) side of the wrapped V-belt. For example, Japanese Patent Publication No. 2020-37257 (Patent Document 2) describes that by cutting the outer portion of an unvulcanized rubber belt covered with an outer sheath fabric in the circumferential direction to expose the rubber layer, and then, in the vulcanization process, arranging multiple unvulcanized rubber belts with the exposed rubber layer in parallel and placing a reinforcing fabric (tie band) on the outer surface before vulcanization, the rubber layer exposed from the unvulcanized rubber belt and the reinforcing fabric (tie band) are bonded by vulcanization, thus improving the adhesive strength compared to conventional methods where the outer sheath fabric and the reinforcing fabric (tie band) are bonded together. Furthermore, Japanese Patent Publication No. 2022-102656 (Patent Document 3) describes a configuration in which the upper part of a semi-vulcanized annular laminated structure (belt body precursor) is buffed with a grinding wheel or sandpaper to remove the reinforcing cloth (outer covering cloth) and expose the semi-vulcanized laminated structure, tie bands are attached to the uneven surfaces of the buffed annular laminated structures, and the semi-vulcanized annular laminated structures to which the tie bands are attached are fully vulcanized. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Special Publication No. 47-34432 [Patent Document 2] Japanese Patent Publication No. 2020-37257 [Patent Document 3] Japanese Patent Publication No. 2022-102656 [Overview of the project] [Problems that the invention aims to solve]

[0012] Fig. 3 shows a schematic partial cross-sectional view of the wrapped joint V-belt disclosed in Patent Documents 2 and 3. The wrapped joint V-belt 121 shown in Fig. 3 is different from the wrapped joint V-belt 111 shown in Fig. 2 in that the outer peripheral surface side of the outer covering cloth 125 that covered the entire surface of the wrapped V-belt portion V has been cut or removed. That is, the wrapped joint V-belt 121 is composed of a belt main body portion in which a plurality of (two in the figure) wrapped V-belt portions V arranged in parallel with a gap in the belt width direction are laminated in the order of a compression rubber layer 122, a core 123, and an extension rubber layer 124 from the inner peripheral side to the outer peripheral side of the belt, and a two-stage outer covering cloth 125 that covers the inner peripheral surface and both side surfaces of this belt main body portion. The two-stage outer covering cloth 125 is overlapped on the inner peripheral side, but at the stage before connection with the tie band T, it was formed of a non-cut (single continuous) cloth like the outer covering cloth 115 of the wrapped joint V-belt 111 shown in Fig. 2. That is, the outer covering cloth 125 was originally a single continuous cloth that covered the entire periphery (including the outer peripheral side) of the belt main body portion, but it was divided into two by cutting the outer peripheral surface side of the wrapped V-belt portion V. The extension rubber layer 124 is exposed due to the cutting of the outer peripheral surface side, and the outer peripheral surface side surface 124a of this exposed extension rubber layer 124 is in direct contact with the tie band T, so it can be bonded or connected to the tie band T with high adhesive force by the vulcanization process.

[0013] However, in the wrapped joint V-belts disclosed in Patent Documents 2 and 3, the side pressure resistance is not sufficient, and when the belt runs for a long time, the tie band is likely to peel off. Furthermore, in the manufacturing methods disclosed in Patent Documents 2 and 3, a process of exposing the rubber layer from the outer peripheral surface (back surface) side after covering the wrapped V-belt portion with the outer covering cloth is required, and in Patent Document 3, a process of further making it in a semi-vulcanized state is also required, so the process becomes complicated and there is a demerit in terms of cost that material loss occurs.

[0014] Therefore, an object of the present invention is to provide a wrapped joint V-belt and a manufacturing method thereof that can improve the adhesive force between the wrapped V-belt portion and the tie band and are also excellent in side pressure resistance.

[0015] Another object of the present invention is to provide a wrapped joint V-belt and a method for manufacturing the same, which can improve the adhesive force between the wrapped V-belt portion and the tie band, have excellent side pressure resistance, and can also improve productivity.

Means for Solving the Problems

[0016] In order to achieve the above object, the inventor of the present invention includes a plurality of wrapped V-belt portions in which a belt body is covered with an outer covering cloth, and a tie band that connects the plurality of wrapped V-belt portions on the outer peripheral surface of each wrapped V-belt portion. The belt body includes a core layer including a core, at least one or more extension rubber layers laminated on the outer peripheral side of the core layer of the belt, and a compression rubber layer laminated on the inner peripheral side of the core layer of the belt. In the wrapped joint V-belt, by exposing the outer peripheral surface of the wrapped V-belt portion without covering it with the outer covering cloth and forming an extension rubber layer formed of a crosslinked rubber composition containing carbon black at a specific ratio, it has been found that the adhesive force between the wrapped V-belt portion and the tie band can be improved and a wrapped joint V-belt excellent in side pressure resistance can be provided, and the present invention has been completed.

[0017] That is, the present invention includes the following aspects.

[0018] Aspect [1]: A wrapped joint V-belt including a plurality of wrapped V-belt portions in which a belt body is covered with an outer covering cloth, and a tie band that connects the plurality of wrapped V-belt portions on the outer peripheral surface of each wrapped V-belt portion, where the belt body includes a core layer including a core, at least one extension rubber layer laminated on the outer peripheral side of the core layer of the belt, and a compression rubber layer laminated on the inner peripheral side of the core layer of the belt, the outer peripheral surface of the wrapped V-belt portion is not covered with the outer covering cloth, and the extension rubber layer is exposed, the exposed extension rubber layer is formed of a crosslinked rubber composition containing a rubber component and carbon black, and the ratio of the carbon black is 20 to 80 parts by mass with respect to 100 parts by mass of the rubber component.

[0019] Embodiment [2]: The wrapped bonded V-belt according to Embodiment [1], wherein the carbon black comprises soft carbon black.

[0020] Embodiment [3]: The wrapped bonded V-belt according to Embodiment [1] or [2], wherein the crosslinked rubber composition further comprises a softening agent, the proportion of the softening agent being 2 to 10 parts by mass per 100 parts by mass of the rubber component.

[0021] Embodiment [4]: ​​The wrapped bonded V-belt according to any of Embodiments [1] to [3], wherein the crosslinked rubber composition contains sulfur as a crosslinking agent.

[0022] Embodiment [5]: The wrapped bonded V-belt according to any of Embodiments [1] to [4], wherein the crosslinked rubber composition further comprises short fibers, and the proportion of the short fibers is 5 to 50 parts by mass per 100 parts by mass of the rubber component.

[0023] Embodiment [6]: A wrapped bonded V-belt according to any of Embodiments [1] to [5], wherein the stretchable rubber layer has a two-layer structure including a first stretchable rubber layer on the outer circumference and a second stretchable rubber layer on the inner circumference, and the rubber hardness of the second stretchable rubber layer is greater than the rubber hardness of the first stretchable rubber layer.

[0024] Embodiment [7]: The wrapped bonded V-belt according to Embodiment [6], wherein the average thickness of the second stretchable rubber layer is greater than the average thickness of the first stretchable rubber layer.

[0025] Embodiment [8]: A wrapped bonded V-belt according to any of Embodiments [1] to [7], wherein a reinforcing fabric layer is interposed between the compression rubber layer and the outer covering.

[0026] Embodiment [9]: A wrapped bonded V-belt according to any of Embodiments [1] to [8], wherein a hard rubber layer is interposed between the core layer and the compression rubber layer.

[0027] Embodiment

[10] : A wrapped bonded V-belt according to any of Embodiments [1] to [9], wherein the tie band includes a bamboo blind fabric.

[0028] Embodiment

[11] : The belt body precursor is covered with an outer covering precursor, and the wrapped V-belt portion A coating process for forming the structure, A method for manufacturing a wrapped V-belt, comprising at least a connecting step of connecting the outer surfaces of a plurality of wrapped V-belt precursors obtained in the coating step with tie band precursors, A method for manufacturing a wrapped bonded V-belt according to any of the embodiments [1] to

[10] , wherein in the coating step, only the inner circumferential surface and both sides of the belt body precursor are coated.

[0029] 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. [Effects of the Invention]

[0030] In the present invention, a wrapped bonded V-belt is provided in which the belt body comprises a plurality of wrapped V-belt sections covered with an outer sheath, and tie bands connecting the plurality of wrapped V-belt sections on the outer circumferential surfaces of each wrapped V-belt section, wherein the belt body comprises a core layer including a core body, at least one stretchable rubber layer laminated on the outer circumferential side of the core layer, and a compression rubber layer laminated on the inner circumferential side of the core layer, and the outer circumferential surface of the wrapped V-belt section is not covered with the outer sheath, but the stretchable rubber layer formed of a crosslinked rubber composition containing carbon black in a specific proportion is exposed, thereby improving the adhesion between the wrapped V-belt section and the tie band, and providing a wrapped bonded V-belt with excellent lateral pressure resistance. Furthermore, there is no need for a step to expose the rubber layer from the outer circumferential side after covering the belt body with the outer sheath, thus improving productivity. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 is a schematic partial cross-sectional perspective view showing an example of a conventional wrapped V-belt. [Figure 2] Figure 2 is a schematic partial cross-sectional view showing another example of a conventional wrapped V-belt. [Figure 3] Figure 3 is a schematic partial cross-sectional view showing yet another example of a conventional wrapped V-belt. [Figure 4] Figure 4 is a schematic partial cross-sectional view showing an example of the wrapped V-belt of the present invention. [Figure 5] Figure 5 is a schematic diagram showing the layout of the three-axis running test machine used to evaluate the durability of the wrapped V-belt obtained in the example. [Modes for carrying out the invention]

[0032] The present invention will be described in detail below, with reference to the attached drawings as necessary. In the following description, elements (or components) that are the same or have common functions may be denoted by the same reference numeral.

[0033] The wrapped V-belt of the present invention comprises a plurality of wrapped V-belt portions (or belt body portions) whose belt body portions are covered with an outer sheath, and tie bands connecting the wrapped V-belt portions on their respective outer surfaces, wherein the outer surfaces of the wrapped V-belt portions are not covered with an outer sheath, and the exposed stretchable rubber layer is formed of a rubber composition containing carbon black in a specific proportion. An example of the wrapped V-belt of the present invention is shown in a schematic partial cross-sectional view in Figure 4.

[0034] As shown in Figure 4, this wrapped V-belt 1 has multiple (two in the figure) wrapped V-belt sections V arranged at intervals and parallel to the belt width direction. The outer surfaces of these two wrapped V-belt sections V are connected by tie bands (connecting members) T, which have a connecting reinforcement layer 2b and a protective layer 2a laminated on the connecting reinforcement layer 2b.

[0035] In this wrapped V-belt 1, the wrapped V-belt portion V consists of a belt body portion in which a reinforcing fabric layer 7, a compression rubber layer 6, a hard rubber layer 5, a core layer 4, and an stretch rubber layer 3 are laminated in that order from the inner circumference side to the outer circumference side (back side) of the belt, and an outer covering fabric 8 that covers the inner surface and both sides of the belt body portion.

[0036] In this wrapped V-belt 1, the stretchable rubber layer 3 has a two-layer structure consisting of a first stretchable rubber layer 3a on the outer circumference of the belt and a second stretchable rubber layer 3b on the inner circumference of the belt. Since the first stretchable rubber layer 3a is exposed on the outer surface of the wrapped V-belt portion, the outer surface of the belt body can come into direct contact with the connecting reinforcement layer 2b of the tie band T. Therefore, the crosslinking that occurs when forming the first stretchable rubber layer 3a allows for bonding or connection with the tie band T with high adhesive strength.

[0037] The core layer 4 is a layer in which core wires (twisted cords) 4a arranged at predetermined intervals in the belt width direction are embedded in the adhesive rubber layer 4b. In the wrapped bonded V-belt of the present invention, the core layer only needs to contain a core, and the core is preferably core wires (twisted cords) arranged at predetermined intervals in the belt width direction. The core wires are not limited to being embedded in the adhesive rubber layer, but may be interposed between the adhesive rubber layer and the stretchable rubber layer, or between the adhesive rubber layer and the hard rubber layer or compression rubber layer, or the core layer may be formed only of core wires (a configuration in which core wires arranged in the belt width direction form the core layer).

[0038] In this example, a hard rubber layer 5 is interposed between the core layer 4 and the compression rubber layer 6, but the compression rubber layer may be formed on the inner circumference side of the core layer without the hard rubber layer interposed. It is preferable to interpose the hard rubber layer because it can improve the lateral pressure resistance of the belt.

[0039] The reinforcing fabric layer 7 has a two-layer structure, including a first reinforcing fabric layer 7a on the outer circumference of the belt and a second reinforcing fabric layer 7b on the inner circumference of the belt. The reinforcing fabric layer is not limited to a two-layer structure, but may also have a single-layer structure or a laminated structure of three or more layers. Furthermore, the wrapped V-belt of the present invention may be a belt without a reinforcing fabric layer, but a belt with a reinforcing fabric layer is preferred in that it can improve resistance to lateral pressure.

[0040] The outer cover 8 has a two-layer structure consisting of a first outer cover (inner outer cover) 8a located on the inside (belt body side) and a second outer cover 8b (outer outer cover) located on the outside. The outer cover may also have a single-layer structure, but in this configuration with multiple layers of outer cover, even if wear progresses on the side of the V-belt portion, the rubber of the belt body can be effectively prevented from being exposed.

[0041] Furthermore, in this example, the outer covering fabric 8 covers the inner circumferential surface and both sides of the belt body, but since it is made of a continuous piece of fabric, in the covering process described later in the manufacturing method section, it is possible to continuously cover the belt along the length direction with a single continuous outer covering fabric precursor (fabric), thereby effectively improving productivity. In this example, the outer covering fabric 8 is made of a continuous piece of fabric with no breaks in the circumferential direction of the belt cross-section (cross-section perpendicular to the length direction of the belt), but it is also possible to use a fabric made by joining (connecting) the ends of two or more pieces of fabric or by partially overlapping and joining them. For example, the outer covering fabric 8 in Figure 4 may be made of two pieces of fabric that are joined by overlapping them on the inner circumferential surface of the belt or on one side (for example, overlapping them on the inner circumferential surface, as in the outer covering fabric 125 of the conventional wrapped V-belt 121 shown in Figure 3). That is, one piece of fabric may continuously cover the inner circumferential surface and one side of the belt, and the other piece of fabric joined to this fabric on the inner circumferential surface of the belt may cover the inner circumferential surface and the other side of the belt. In this embodiment, the inner circumferential surface of the belt can be effectively reinforced without forming a belt body portion on the inner circumferential surface side of the compressed rubber layer with a reinforcing fabric layer.

[0042] [Belt body and wrapped V-belt section] The belt body is covered on its inner circumferential surface and both sides by an outer covering, forming a wrapped V-belt section. The wrapped V-belt section may consist of an endless, V-shaped cross-section belt body (belt body section) having at least an outer stretch rubber layer, an inner compression rubber layer, and a core layer interposed between the stretch rubber layer and the compression rubber layer, and the outer covering (cover cloth) covering the inner circumferential surface and both sides of the V-shaped cross-section of the belt body over its entire length in the belt length direction (belt circumferential direction), with the left and right sides of the V-shaped cross-section covered by the outer covering serving as friction transmission surfaces. In the V-shaped cross-section, the side with the wider belt width is the outer circumferential side, and the side with the narrower belt width is the inner circumferential side. Furthermore, the belt body may optionally have a hard rubber layer between the core layer and the compression rubber layer, and a reinforcing cloth layer on the inner circumferential surface side of the compression rubber layer.

[0043] (Stretchable rubber layer) The stretchable rubber layer forms the outer surface that contacts the tie band, and may be a single-layer structure or a laminated structure. Of these, a single-layer structure and a double-layer structure are preferred. A single-layer structure is preferred because it allows for the manufacture of a belt with excellent properties in a simple structure, while a double-layer structure consisting of a first stretchable rubber layer on the outer circumference and a second stretchable rubber layer on the inner circumference is preferred because it easily balances adhesion to the tie band and lateral pressure resistance.

[0044] (First crosslinked rubber composition) The stretchable rubber layer that forms the outer circumferential surface of the belt body and comes into contact with the tie band (particularly the stretchable rubber layer in a single-layer structure and the first stretchable rubber layer in a double-layer structure) is made of a cross-linked rubber composition (first cross-linked rubber composition) containing rubber components and carbon black.

[0045] (1A) First rubber component The rubber components constituting the first crosslinked rubber composition (first rubber components) can be selected from known vulcanizable or crosslinkable rubbers and / or elastomers, for example, diene rubbers [natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber (CR), styrene-butadiene rubber (SBR), vinylpyridine-styrene-butadiene copolymer rubber, acrylonitrile butadiene rubber (nitrile rubber); hydrogenated versions of the diene rubbers such as hydrogenated nitrile rubber (including a mixed polymer of hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt)], olefin rubbers [for example, ethylene-α-olefin rubber (ethylene-α-olefin elastomer), polyoctenylene rubber, ethylene-vinyl acetate copolymer rubber, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber], epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluororubber, etc. These rubber components can be used individually or in combination of two or more.

[0046] Of these, ethylene-α-olefin elastomers (ethylene-α-olefin rubbers) such as ethylene-propylene copolymer (EPM), ethylene-propylene-non-conjugated diene terpolymer (EPDM), ethylene-1-butene-non-conjugated diene copolymer (EBDM), and ethylene-1-octene-non-conjugated diene copolymer (EODM), and chloroprene rubber are commonly used because the crosslinking agent (or vulcanizing agent) and crosslinking accelerator (or vulcanization accelerator) diffuse easily. In particular, ethylene-α-olefin elastomers such as chloroprene rubber and EPDM are preferred because they have an excellent balance of mechanical strength, weather resistance, heat resistance, cold resistance, oil resistance, and adhesion. Chloroprene rubber is especially preferred because it is relatively inexpensive while having excellent abrasion resistance, heat resistance, and adhesion to fabric. Chloroprene rubber may be sulfur-modified or non-sulfur-modified.

[0047] The proportion of the first rubber component is 20 to 80% by mass, preferably 30 to 75% by mass, more preferably 35 to 70% by mass, more preferably 40 to 65% by mass, and most preferably 50 to 60% by mass in the first crosslinked rubber composition.

[0048] (1B) 1st Carbon Black The carbon black contained in the first crosslinked rubber composition (first carbon black) can generally be classified into either hard carbon black, which has a relatively small particle size, or soft carbon black, which has a relatively large particle size. While the classification of carbon black is sometimes based on the average particle size in the raw material state (average primary particle size), in this application, it is based on the primary particle size of the carbon black contained in the rubber composition (particularly in the crosslinked rubber composition). That is, in this application, the primary particle size of each primary particle of carbon black contained in the rubber composition is measured, and carbon black with a primary particle size of 1 nm or more and less than 40 nm is referred to as hard carbon black (or hard carbon), and carbon black with a primary particle size of 40 nm or more (e.g., 40 to 300 nm) is referred to as soft carbon black (or soft carbon).

[0049] The average primary particle size of hard carbon black may be, for example, 10 to 38 nm, preferably 15 to 35 nm, more preferably 20 to 33 nm, and more preferably 25 to 30 nm. On the other hand, the average primary particle size of soft carbon black may be, for example, 40 to 100 nm, preferably 41 to 80 nm, more preferably 42 to 78 nm (e.g., 42 to 60 nm), more preferably 43 to 75 nm (e.g., 43 to 50 nm), and most preferably 50 to 73 nm (especially 60 to 70 nm).

[0050] In this application, the average particle diameter of carbon black can be measured using, for example, a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and can be calculated as the arithmetic mean particle diameter of an appropriate number of samples (for example, any 50 samples) through image analysis.

[0051] In the present invention, it is preferable that the first carbon black includes soft carbon black. Hard carbon black with a primary particle size of less than 40 nm has high reinforcing properties and is effective in increasing lateral pressure resistance, but it may increase internal heat generation and accelerate the peeling of the tie band. Therefore, in the present invention, by including soft carbon black as the first carbon black, lateral pressure resistance may be increased while reducing internal heat generation. When the carbon black includes soft carbon, the soft carbon black can reduce internal heat generation and suppress the rise in belt temperature, thereby maintaining high adhesion to the tie band.

[0052] The proportion of soft carbon black (percentage of particles) may be 10% or more of the first carbon black, preferably 50% or more, more preferably 80% or more, more preferably 90% or more, and most preferably 100%. If the proportion of soft carbon black is too low, the adhesion to the tie band may decrease.

[0053] In this application, the ratio of soft carbon black to hard carbon black particle numbers can be calculated based on the primary particle size measured using a transmission electron microscope.

[0054] The amount of iodine adsorbed by the first carbon black is, for example, 5 to 200 g / kg, preferably 10 to 100 g / kg, more preferably 15 to 80 g / kg, more preferably 20 to 70 g / kg, and most preferably 25 to 50 g / kg (for example, 30 to 50 g / kg). If the amount of iodine adsorbed is too small, the reinforcing properties may decrease, and if it is too large, the adhesion to the tie band may decrease.

[0055] In this application, the amount of iodine adsorbed by carbon black can be measured in accordance with the standard test method of ASTM D1510-17.

[0056] The BET specific surface area of ​​carbon black is, for example, 10-300 m². 2 / g, preferably 20-100m 2 / g, more preferably 23-70m2 / g (for example, 30-70m) 2 ( / g), more comfortably 25-60m 2 / g (for example, 40-60m) 2 It is / g).

[0057] In this application, BET specific surface area refers to the specific surface area measured using nitrogen gas by the BET method.

[0058] The DBP absorption amount (DBP oil absorption amount) of the first carbon black is, for example, 30 to 300 mL / 100 g (e.g., 120 to 300 mL / 100 g), preferably 50 to 200 mL / 100 g (e.g., 120 to 200 mL / 100 g), more preferably 60 to 150 mL / 100 g (e.g., 100 to 150 mL / 100 g), and more preferably 65 to 120 mL / 100 g (e.g., 110 to 120 mL / 100 g).

[0059] In this application, the DBP absorption amount of carbon black refers to the value (OAN) that can be measured for an uncompressible sample, in accordance with JIS K 6217-4 (2017).

[0060] The proportion of the first carbon black is 20 to 80 parts by mass per 100 parts by mass of the first rubber component, preferably 23 to 75 parts by mass, more preferably 25 to 70 parts by mass, and more preferably 30 to 60 parts by mass. If the first crosslinked rubber composition does not contain short fibers, the proportion of the first carbon black may be 30 to 80 parts by mass per 100 parts by mass of the first rubber component, preferably 35 to 80 parts by mass, more preferably 40 to 78 parts by mass, and more preferably 60 to 75 parts by mass. If the proportion of the first carbon black is too low, the lateral pressure resistance may decrease, and if it is too high, the adhesion to the tie band may decrease.

[0061] When the stretchable rubber layer has a two-layer structure consisting of a first stretchable rubber layer on the outer circumference of the belt and a second stretchable rubber layer on the inner circumference of the belt, the proportion of the first carbon black in the first stretchable rubber layer is 20 to 80 parts by mass per 100 parts by mass of the first rubber component, preferably 25 to 60 parts by mass, more preferably 30 to 50 parts by mass, and more preferably 35 to 45 parts by mass. If the proportion of the first carbon black is too low, the lateral pressure resistance may decrease, and if it is too high, the adhesion to the tie band may decrease.

[0062] (1C) First softening agent (or first plasticizer) The first crosslinked rubber composition preferably further contains a softening agent (first softening agent). Examples of the first softening agent (first plasticizer) include oil-based softening agents [paraffinic oils, alicyclic oils (naphthenic oils), aromatic oils, etc.], aliphatic carboxylic acid softening agents (adipate ester softening agents, sebacate ester softening agents, etc.), aromatic carboxylic acid ester softening agents (phthalate ester softening agents, trimellitic ester softening agents, etc.), oxycarboxylic acid ester softening agents, phosphate ester softening agents, ether softening agents, and ether ester softening agents. These softening agents can be used alone or in combination of two or more. Among these softening agents, oil-based softening agents and aromatic carboxylic acid ester softening agents are preferred.

[0063] The proportion of the first softener is, for example, 1 to 15 parts by mass, preferably 2 to 10 parts by mass, more preferably 3 to 8 parts by mass, and more preferably 5 to 7 parts by mass, per 100 parts by mass of the first rubber component. If the proportion of the first softener is too low, the adhesion to the tie band may decrease, and if it is too high, the adhesion to the tie band may also decrease.

[0064] (1D) First crosslinking agent The first crosslinked rubber composition preferably further contains a crosslinking agent (first crosslinking agent). Examples of the first crosslinking agent include organic peroxides, sulfur-based crosslinking agents, and metal oxides. These crosslinking agents can be used alone or in combination of two or more. Of these, organic peroxides, sulfur-based crosslinking agents, and metal oxides are preferred, and when the first rubber component is chloroprene rubber, a combination of a sulfur-based crosslinking agent and a metal oxide is particularly preferred. When the first rubber component is chloroprene rubber, sulfur-free crosslinking with a metal oxide is possible, but by combining a metal oxide and a sulfur-based crosslinking agent, the crosslinking density of the stretched rubber layer in contact with the tie band can be improved, thereby improving the adhesion strength and lateral pressure resistance with the tie band.

[0065] 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. Of these, sulfur such as powdered sulfur is preferred.

[0066] 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. Of these, magnesium oxide and zinc oxide are preferred, and a combination of magnesium oxide and zinc oxide is particularly preferred.

[0067] When the first rubber component is an ethylene-α-olefin elastomer, organic peroxides are particularly preferred. 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 alone or in combination of two or more.

[0068] The proportion of the first crosslinking agent is, for example, 1 to 30 parts by mass, preferably 3 to 25 parts by mass, more preferably 5 to 20 parts by mass, more preferably 6 to 18 parts by mass, and most preferably 7 to 15 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 crosslinking density may decrease, which may reduce the lateral pressure resistance and adhesion to the tie band. If it is too high, the flexibility of the belt may decrease.

[0069] The proportion of the sulfur-based crosslinking agent (first sulfur-based crosslinking agent) 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, more preferably 0.5 to 2.5 parts by mass (for example 0.5 to 2 parts by mass), and most preferably 0.8 to 2.2 parts by mass (for example 0.8 to 1.5 parts by mass) per 100 parts by mass of the first rubber component.

[0070] The proportion of the metal oxide (first metal oxide) is, for example, 1 to 20 parts by mass, preferably 3 to 18 parts by mass, more preferably 5 to 15 parts by mass, more preferably 6 to 13 parts by mass, and most preferably 7 to 12 parts by mass, per 100 parts by mass of the first rubber component.

[0071] When a first sulfur-based crosslinking agent and a first metal oxide are combined as the first crosslinking agent, the mass ratio of the two may be 50 / 50 to 1 / 99, preferably 40 / 60 to 2 / 98, more preferably 30 / 70 to 3 / 97, more preferably 20 / 80 to 5 / 95, and most preferably 15 / 85 to 7 / 93. If the ratio of the first sulfur-based crosslinking agent is too low, the crosslinking density may decrease, which may reduce lateral pressure resistance and adhesion to the tie band. If it is too high, the flexibility of the belt may decrease.

[0072] The proportion of the organic peroxide (first organic peroxide) is, 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, per 100 parts by mass of the first rubber component.

[0073] (1E) First short fiber The first crosslinked rubber composition may further contain short fibers (first short fibers). Examples of fibers constituting the first short fibers include synthetic fibers such as polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), polyamide fibers (aliphatic polyamide fibers, aramid fibers, etc.), polyester fibers (polyalkylene arylate fibers, etc.), vinyl alcohol fibers (polyvinyl alcohol fibers, ethylene-vinyl alcohol copolymer fibers, vinylon fibers, etc.), and poly(p-phenylene)benzobisoxazole (PBO) fibers; cellulose fibers (cellulose fibers or cotton, cellulose derivative fibers, etc.), natural fibers such as hemp and wool; and inorganic fibers such as carbon fibers. These fibers may be used individually or in combination of two or more types.

[0074] Of these fibers, polyamide fibers, polyester fibers, and cellulose fibers are preferred, at least one selected from the group consisting of aliphatic polyamide fibers, aramid fibers, polyalkylene arylate fibers, and cellulose fibers is more preferred, and at least one selected from the group consisting of aliphatic polyamide fibers, polyalkylene arylate fibers, and cellulose fibers is even more preferred. In particular, when the first crosslinked rubber composition is the rubber composition of the first stretchable rubber layer, a combination of short fibers formed from aliphatic polyamide fibers (aliphatic polyamide short fibers) and short fibers formed from cellulose fibers (cellulose short fibers) is particularly preferred in order to improve adhesion to the tie band.

[0075] Examples of aliphatic polyamide fibers include polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers, polyamide 11 fibers, and polyamide 12 fibers. Of these, polyamide 6 fibers and polyamide 66 fibers are preferred.

[0076] Cellulosic fibers include cellulose fibers (cellulose fibers derived from plants, animals, or bacteria, etc.) and cellulose derivative fibers. Examples of cellulose fibers include natural plant-derived cellulose fibers (pulp fibers) such as wood pulp (coniferous and hardwood pulp, etc.), bamboo fibers, sugarcane fibers, seed hair fibers (cotton fibers (cotton linters), kapok, etc.), ginseng fibers (hemp, paper mulberry, mitsumata, etc.), and leaf fibers (Manila hemp, New Zealand hemp, etc.); animal-derived cellulose fibers such as ascidian cellulose; bacterial cellulose fibers; and algal cellulose. Examples of cellulose derivative fibers include cellulose ester fibers and regenerated cellulose fibers (rayon, cupro, lyocell, etc.). Of these, cellulose fibers such as cotton are preferred.

[0077] When combining aliphatic polyamide short fibers and cellulosic short fibers, the ratio of the two is, for example, former / latter (mass ratio) = 90 / 10 to 10 / 90, preferably 80 / 20 to 20 / 80, more preferably 70 / 30 to 30 / 70, and more preferably 60 / 40 to 40 / 60. In applications where resistance to lateral pressure is important, the ratio of the two may be former / latter (mass ratio) = 50 / 50 to 10 / 90, preferably 30 / 70 to 15 / 85.

[0078] The average fiber diameter of the first short fibers may be 2 μm or more, for example, 2 to 100 μm, preferably 5 to 80 μm, more preferably 10 to 50 μm, and more preferably 20 to 40 μm.

[0079] The average fiber length of the first short fibers is, for example, 1 to 20 mm, preferably 1.5 to 10 mm, more preferably 2 to 8 mm, and more preferably 2.5 to 6 mm.

[0080] The first short fibers may be subjected to conventional bonding treatments (or surface treatments) [for example, treatment with a treatment solution containing an adhesive component] from the viewpoint of dispersibility and adhesion of the short fibers in the rubber composition. Examples of adhesive components (or surface treatment agents) used for bonding treatments include isocyanate compounds (polyisocyanate compounds), epoxy resins (epoxy compounds), silane coupling agents, amino resins, rubber components (rubber latex or rubber glue, etc.), and RFL liquids containing resorcinol (R), formaldehyde (F), and rubber or latex (L) [for example, an RFL liquid in which resorcinol (R) and formaldehyde (F) form a condensate (RF condensate) and contains a rubber component such as vinylpyridine-styrene-butadiene copolymer rubber]. These adhesive components may be used individually or in combination of two or more, and the same or different adhesive components may be used to sequentially treat the material multiple times.

[0081] The first short fibers may be embedded in the rubber composition (rubber layer) oriented in the belt width direction in order to suppress compressive deformation of the belt against pressure from the pulley (from the viewpoint of improving lateral pressure resistance).

[0082] The proportion of the first short fibers is, for example, 5 to 55 parts by mass, preferably 5 to 50 parts by mass, more preferably 10 to 50 parts by mass, and more preferably 15 to 40 parts by mass, per 100 parts by mass of the first rubber component. In applications where lateral pressure resistance is important, the proportion of the first short fibers may be 20 to 55 parts by mass, preferably 30 to 50 parts by mass, per 100 parts by mass of the first rubber component. If the proportion of the first short fibers is too low, the lateral pressure resistance may decrease, and if it is too high, the adhesion to the tie band may decrease.

[0083] When the stretchable rubber layer has a two-layer structure consisting of a first stretchable rubber layer on the outer circumference of the belt and a second stretchable rubber layer on the inner circumference of the belt, the proportion of first short fibers in the first stretchable rubber layer is, for example, 10 to 50 parts by mass, preferably 13 to 40 parts by mass, more preferably 15 to 30 parts by mass, and most preferably 17 to 25 parts by mass, per 100 parts by mass of the first rubber component. If the proportion of first short fibers is too low, the lateral pressure resistance may decrease, and if it is too high, the adhesion to the tie band may decrease.

[0084] (1F) 1st Other Additives The first crosslinked rubber composition may further contain other additives (first other additives), which are conventional additives used in rubber formulations.

[0085] Conventional additives include, for example, first crosslinking aids (crosslinking accelerators such as thiazole-based accelerators; cocrosslinking agents such as bismaleimides), first filling agents (first reinforcing fillers such as silica; first non-reinforcing fillers such as calcium carbonate), first processing agents or processing aids (stearic acid or its metal salts, waxes, paraffins, fatty acid amides, etc.), first anti-aging agents (antioxidants, heat aging inhibitors, flex crack inhibitors, ozone degradation inhibitors, etc.), colorants, adhesion improvers, tackifiers, 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.

[0086] In particular, the proportion of the first crosslinking aid is, for example, 0.1 to 10 parts by mass, preferably 0.3 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and more preferably 0.8 to 2 parts by mass, per 100 parts by mass of the first rubber component.

[0087] The proportion of the first filler compound is, for example, 5 to 200 parts by mass, preferably 10 to 150 parts by mass, more preferably 15 to 100 parts by mass, more preferably 20 to 50 parts by mass, and most preferably 22 to 40 parts by mass, per 100 parts by mass of the first rubber component. As the first filler compound, a first non-reinforcing filler such as calcium carbonate is preferred, and by combining it with carbon black, it becomes easier to balance economy and lateral pressure resistance.

[0088] The proportion of the first processing agent or processing aid is, for example, 0.1 to 20 parts by mass, preferably 0.3 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and more preferably 0.8 to 2 parts by mass, per 100 parts by mass of the first rubber component.

[0089] The proportion of the first anti-aging agent is, for example, 0.5 to 20 parts by mass, preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and more preferably 3 to 5 parts by mass, per 100 parts by mass of the first rubber component.

[0090] The total proportion of the first other additive is, for example, 0.1 to 50 parts by mass, preferably 0.5 to 30 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the first rubber component.

[0091] (1G) Properties of the first crosslinked rubber composition The rubber hardness of the stretchable rubber layer formed with the first crosslinked rubber composition is a type A hardness, which can be selected from a range of approximately 80 to 99, preferably 82 to 95, and more preferably 83 to 93. If the hardness of the stretchable rubber layer is too low, the lateral pressure resistance may decrease, and if it is too high, the adhesion to the tie band may decrease.

[0092] When the stretchable rubber layer has a two-layer structure consisting of a first stretchable rubber layer on the outer circumference of the belt and a second stretchable rubber layer on the inner circumference of the belt, the rubber hardness of the first stretchable rubber layer formed from the first crosslinked rubber composition can be selected from a range of approximately 80 to 89 on the Type A hardness scale, preferably 81 to 88, more preferably 82 to 87, even more preferably 83 to 86, and most preferably 84 to 86. If the hardness of the first stretchable rubber layer is too low, the lateral pressure resistance may decrease, and if it is too high, the adhesion to the tie band may decrease.

[0093] In this application, the Type A hardness of each rubber layer refers to the value (Type A) measured using a 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.

[0094] When the stretchable rubber layer has a single-layer structure, the average thickness of the stretchable rubber layer is, for example, 0.5 to 10 mm, preferably 1 to 5 mm, more preferably 1.5 to 4 mm, more preferably 2 to 3.5 mm, and most preferably 2.5 to 3 mm.

[0095] When the stretchable rubber layer has a two-layer structure consisting of a first stretchable rubber layer and a second stretchable rubber layer, the average thickness of the first stretchable rubber layer is, for example, 0.3 to 5 mm, preferably 0.5 to 3 mm, more preferably 0.8 to 2 mm, more preferably 1 to 1.8 mm, and most preferably 1.2 to 1.5 mm.

[0096] In this application, the average thickness of each layer is determined as the average value of any 10 points.

[0097] (Second crosslinked rubber composition) If the stretchable rubber layer has a two-layer structure consisting of a first stretchable rubber layer on the outer circumference of the belt and a second stretchable rubber layer on the inner circumference of the belt, the second stretchable rubber layer may be formed of a second crosslinked rubber composition containing a second rubber component and a second carbon black.

[0098] (2A) Second rubber component The second rubber component 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 adhesion with the first stretchable rubber layer.

[0099] The proportion of the second rubber component is 20 to 80% by mass, preferably 30 to 75% by mass, more preferably 35 to 70% by mass, more preferably 40 to 60% by mass, and most preferably 45 to 50% by mass in the second crosslinked rubber composition.

[0100] (2B) Second Carbon Black The second carbon black can be selected from the carbon blacks exemplified as the first carbon black, including preferred embodiments.

[0101] In the second carbon black, the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount can also be selected from the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount in the first carbon black, including preferred ranges.

[0102] The proportion of the second carbon black is, for example, 10 to 100 parts by mass, preferably 30 to 90 parts by mass, more preferably 40 to 80 parts by mass, more preferably 50 to 70 parts by mass, and most preferably 55 to 65 parts by mass, per 100 parts by mass of the second rubber component. If the proportion of the second carbon black is too low, the lateral pressure resistance may decrease, and if it is too high, the interlayer adhesion may decrease.

[0103] (2C) Second softening agent (or second plasticizer) The second crosslinked rubber composition preferably further contains a softener (second softener). The second softener can be selected from the softeners exemplified above as the first softener, including preferred embodiments. The proportion of the second softener is, for example, 0.5 to 10 parts by mass, preferably 1 to 7 parts by mass, more preferably 2 to 7 parts by mass, and more preferably 3 to 5 parts by mass, per 100 parts by mass of the second rubber component.

[0104] (2D) Second crosslinking agent The second crosslinked rubber composition preferably further contains a crosslinking agent (second crosslinking agent). The second crosslinking agent can be selected from the crosslinking agents exemplified as the first crosslinking agent, including preferred embodiments. In the second crosslinking agent, the proportion of the second crosslinking agent, the proportion of the second sulfur-based crosslinking agent, the proportion of the second metal oxide, and the mass ratio of the second sulfur-based crosslinking agent to the second metal oxide can be selected from the respective proportions and mass ratios in the first crosslinking agent, including preferred ranges.

[0105] (2E) Second short fiber The second crosslinked rubber composition may further contain short fibers (second short fibers). Examples of fibers constituting the second short fibers include the fibers exemplified as the first short fibers. The fibers can be used alone or in combination of two or more types. Among the fibers, aramid fibers, PBO fibers, and inorganic fibers are preferred, with aramid fibers being particularly preferred, from the viewpoint of improving lateral pressure resistance.

[0106] The average fiber diameter and average fiber length of the second short fiber can be selected from the average fiber diameter and average fiber length of the first short fiber, including a preferred range.

[0107] The second short fiber may be subjected to conventional bonding treatments from the viewpoint of dispersibility and adhesion of the short fibers in the rubber composition. The adhesive component used for the bonding treatment can be selected from the adhesive components exemplified as adhesive components used for bonding the first short fiber, including preferred embodiments.

[0108] The second short fibers may be embedded in the rubber composition (rubber layer) oriented in the belt width direction in order to suppress compressive deformation of the belt due to pressure from the pulley.

[0109] The proportion of the second short fibers is, for example, 5 to 50 parts by mass, preferably 10 to 50 parts by mass, more preferably 15 to 40 parts by mass, more preferably 20 to 35 parts by mass, and most preferably 23 to 30 parts by mass, per 100 parts by mass of the second rubber component. If the proportion of the second short fibers is too low, the lateral pressure resistance may decrease, and if it is too high, the interlaminar adhesion may decrease.

[0110] (2F) Second Other Additives The second crosslinked rubber composition may further contain other additives (second other additives). The second other additive can be selected from the first other additive, including preferred embodiments. The proportion of the second other additive can be selected from a range of proportions of the first other additive, including preferred ranges.

[0111] (2G) Properties of the second crosslinked rubber composition The rubber hardness of the second stretchable rubber layer formed with the second crosslinked rubber composition is a type A hardness, which can be selected from a range of approximately 85 to 99, preferably 86 to 98, more preferably 87 to 97, more preferably 90 to 95, and most preferably 92 to 94. If the hardness of the second stretchable rubber layer is too low, the lateral pressure resistance may decrease, and if it is too high, the interlayer adhesion may decrease.

[0112] In the present invention, it is preferable that the rubber hardness of the second stretchable rubber layer is greater than that of the first stretchable rubber layer. By increasing the rubber hardness of the second stretchable rubber layer located on the inner circumference, the resistance to lateral pressure can be improved, and it becomes easier to approximate the rubber hardness of the first stretchable rubber layer located on the outer circumference and in contact with the tie band to the rubber hardness of the tie band. This suppresses stress concentration at the interface between the stretchable rubber layer and the tie band, and improves adhesion to the tie band.

[0113] The difference in rubber hardness between the second stretchable rubber layer and the first stretchable rubber layer (rubber hardness of the second stretchable rubber layer - rubber hardness of the first stretchable rubber layer) is, for example, 1 to 20, preferably 3 to 15, more preferably 5 to 12, more preferably 6 to 10, and most preferably 7 to 9.

[0114] The average thickness of the second stretchable rubber layer is, for example, 0.3 to 5 mm, preferably 0.5 to 3 mm, more preferably 1 to 2.5 mm, more preferably 1.2 to 2 mm, and most preferably 1.3 to 1.7 mm.

[0115] In this invention, it is preferable that the average thickness of the second stretchable rubber layer is greater than the average thickness of the first stretchable rubber layer. Even if the thickness of the first stretchable rubber layer is small, it is easy to exhibit the effect of mitigating stress concentration between it and the tie band. In addition, by increasing the thickness of the second stretchable rubber layer, the lateral pressure resistance can be improved. Therefore, it is effective to make the average thickness of the second stretchable rubber layer greater than the average thickness of the first stretchable rubber layer. By combining such a thickness relationship with a rubber hardness within the aforementioned range, lateral pressure resistance can be further enhanced, and durability can be improved.

[0116] The difference in average thickness between the second stretchable rubber layer and the first stretchable rubber layer (average thickness of the second stretchable rubber layer - average thickness of the first stretchable rubber layer) is, for example, 0.05 to 5 mm, preferably 0.1 to 0.3 mm, and more preferably 0.15 to 0.25 mm.

[0117] (Core layer) The core layer only needs to contain a core, and may be a core layer formed solely of cores. In this application, when the core layer is formed solely of cores, cores arranged at intervals within the belt body are referred to as the core layer, and such a core layer includes not only a form in which the core is arranged at the interface between the stretchable rubber layer and the compression rubber layer (or hard rubber layer), but also a form in which part or all of the core arranged at the interface between the stretchable rubber layer and the compression rubber layer (or hard rubber layer) is embedded in the stretchable rubber layer or the compression rubber layer (or hard rubber layer) during the manufacturing process.

[0118] Furthermore, the core layer may be a core layer formed solely of the core, but it is preferable that the core layer consists of a core and an adhesive rubber layer formed of a crosslinked rubber composition containing the core, in order to suppress delamination between layers and improve belt durability. In a core layer consisting of an adhesive rubber layer containing a core, the core is embedded in a layer formed of a crosslinked rubber composition containing rubber components. The adhesive rubber layer is interposed between the stretchable rubber layer and the compression rubber layer (or hard rubber layer) to bond the stretchable rubber layer, the compression rubber layer (or hard rubber layer), and the core. In this application, the adhesive rubber layer includes not only a form in which the entire core is embedded in the adhesive rubber layer, but also a form in which the core is disposed at the interface between the adhesive rubber layer and the stretchable rubber layer or compression rubber layer (or hard rubber layer).

[0119] (Core body) The core is preferably made of stranded wires arranged at predetermined intervals in the belt width direction. The strands are arranged extending in the length direction of the belt, and are usually arranged in parallel at a predetermined pitch parallel to the length direction of the belt. When the core (strands) is embedded in the adhesive rubber layer, it is sufficient for only a part of it to be embedded in the adhesive rubber layer, and it may also be the case that the strands are embedded in the adhesive rubber layer (the entire strand is completely embedded in the adhesive rubber layer) in order to improve durability.

[0120] Examples of fibers constituting the core wire include the fibers exemplified as the first short fibers. These fibers can be used individually or in combination of two or more types.

[0121] Among the aforementioned fibers, ethylene terephthalate, ethylene-2,6-naphthalate, etc., are selected from the viewpoint of high modulus. 2-4 Alkylene-C 6-14 Synthetic fibers such as polyester fibers (polyalkylene arylate fibers) and polyamide fibers (such as aramid fibers), which have arylate as their main constituent unit, and inorganic fibers such as carbon fibers are commonly used. Polyester fibers (especially polyethylene terephthalate fibers and polyethylene naphthalate fibers) and polyamide fibers (especially aramid fibers) are preferred, and polyamide fibers such as aramid fibers are particularly preferred.

[0122] These fibers may be used in the form of multifilament yarn containing multiple filaments. The fineness of the multifilament yarn may be, for example, around 1000 to 3000 dtex (e.g., 1200 to 2000 dtex). The multifilament yarn may contain, for example, around 100 to 3000 filaments (e.g., 500 to 2000 filaments), and preferably around 700 to 1300 filaments.

[0123] As the core wire, a twisted cord using multifilament yarn (e.g., multi-ply, single-ply, Lang-ply, etc., preferably multi-ply) can be used. The average wire diameter of the core wire (diameter of the twisted cord) may be, for example, 0.5 to 3 mm, preferably 0.6 to 2.5 mm, and more preferably about 0.7 to 2 mm. The total fineness of the twisted cord may be, for example, about 10,000 to 50,000 dtex (e.g., about 22,000 to 28,000 dtex). The twisted cord may contain, for example, about 1,000 to 30,000 filaments (e.g., about 5,000 to 25,000 filaments), preferably about 10,000 to 20,000 filaments (e.g., about 12,000 to 18,000 filaments). The twist coefficient of the lower twisted yarn in the twisted cord may be, for example, around 2 to 4 (for example, 2.5 to 3.5), and the twist coefficient of the upper twisted yarn may also be, for example, around 2 to 4 (for example, 2.5 to 3.5).

[0124] The core wire may be subjected to conventional bonding treatment to improve its adhesion to the crosslinked rubber composition. The adhesive component used for bonding treatment can be selected from the adhesive components exemplified as adhesive components used for bonding treatment of the first short fibers, including preferred embodiments.

[0125] (Adhesive rubber layer) The adhesive rubber layer may be formed from a third crosslinked rubber composition containing a third rubber component.

[0126] (3A) Third rubber component The third rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The third rubber component is preferably of the same series or type as the first rubber component (or the second rubber component if the stretchable rubber layer has a two-layer structure), and more preferably of the same type, in order to improve adhesion with the stretchable rubber layer (or the second stretchable rubber layer if the stretchable rubber layer has a two-layer structure).

[0127] The proportion of the third rubber component is 20 to 80% by mass, preferably 30 to 75% by mass, more preferably 35 to 70% by mass, more preferably 40 to 65% by mass, and most preferably 50 to 60% by mass in the third crosslinked rubber composition.

[0128] (3B) Third Carbon Black The third crosslinked rubber composition may further contain a third carbon black. The third carbon black can be selected from the carbon blacks exemplified as the first carbon black, including in preferred embodiments.

[0129] In the third carbon black, the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount can also be selected from the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount in the first carbon black, including preferred ranges.

[0130] The proportion of the third carbon black is, for example, 5 to 100 parts by mass, preferably 7 to 70 parts by mass, more preferably 10 to 50 parts by mass, and more preferably 20 to 40 parts by mass, per 100 parts by mass of the third rubber component. If the proportion of the third carbon black is too low, the lateral pressure resistance may decrease, and if it is too high, the adhesion to the core and adjacent rubber layers may decrease.

[0131] (3C) Third Silica The third crosslinked rubber composition may further contain silica (third silica) in order to improve its tackiness (adhesion).

[0132] The third silica includes dry silica, wet silica, surface-treated silica, etc. Also, the third silica can be classified into, for example, dry-process white carbon, wet-process white carbon, colloidal silica, precipitated silica, etc. according to the production method. The third silica may be amorphous silica. These silicas can be used alone or in combination of two or more. Among these silicas, silica having a surface silanol group (anhydrous silicic acid, hydrous silicic acid) is preferred, and hydrous silicic acid having a large number of surface silanol groups has a strong chemical bonding force with the rubber component.

[0133] The average particle diameter (average primary particle diameter) of the third silica is, for example, 1 to 500 nm, preferably 3 to 300 nm, more preferably 5 to 100 nm, and even more preferably 10 to 50 nm.

[0134] In the present application, as a method for measuring the average particle diameter of the third silica, for example, it can be measured using SEM, TEM, etc., and can be calculated as the arithmetic average particle diameter of an appropriate number of samples (for example, any 50 samples) by image analysis.

[0135] The BET specific surface area of the third silica is, for example, 50 to 400 m 2 / g, preferably 100 to 300 m 2 / g, more preferably 150 to 200 m 2 / g.

[0136] The proportion of the third silica is, for example, 5 to 100 parts by mass, preferably 7 to 70 parts by mass, more preferably 10 to 50 parts by mass, and even more preferably 20 to 40 parts by mass with respect to 100 parts by mass of the third rubber component.

[0137] (3D) The third softening agent (or plasticizer) The third crosslinked rubber composition may further contain a third softening agent. The third softening agent can be selected from the softening agents exemplified as the first softening agent including preferred embodiments. The proportion of the third softening agent is, for example, 1 to 50 parts by mass, preferably 5 to 40 parts by mass, more preferably 10 to 30 parts by mass, and even more preferably 15 to 25 parts by mass with respect to 100 parts by mass of the third rubber component.

[0138] (3E) Third crosslinking agent The third crosslinked rubber composition may further contain a third crosslinking agent. Examples of the third crosslinking agent include the crosslinking agents exemplified above as the first crosslinking agent. The crosslinking agents can be used alone or in combination of two or more. Among the crosslinking agents, metal oxides are preferred.

[0139] The proportion of the third crosslinking agent is, for example, 1 to 20 parts by mass, preferably 3 to 18 parts by mass, more preferably 5 to 15 parts by mass, more preferably 6 to 13 parts by mass, and most preferably 7 to 12 parts by mass, per 100 parts by mass of the third rubber component.

[0140] (3F) Third staple fiber The third crosslinked rubber composition may further contain a third staple fiber. The third staple fiber can be selected from the staple fibers exemplified as the first staple fiber, including in preferred embodiments. The proportion of the third staple fiber is 30 parts by mass or less, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the third rubber component. The third crosslinked rubber composition may not contain the third staple fiber.

[0141] (3G) Third Other Additive The third crosslinked rubber composition may further contain other additives (third other additives). The third other additive can be selected from the first other additives, including preferred embodiments. The proportion of the third other additive can be selected from a range of proportions of the first other additives, including a preferred range.

[0142] (3H) Properties of the third crosslinked rubber composition The rubber hardness of the adhesive rubber layer formed with the third crosslinked rubber composition is, for example, 60 to 85, preferably 65 to 82, more preferably 70 to 80, and even more preferably 73 to 77, on a Type A hardness scale.

[0143] The average thickness of the core layer is, for example, 1 to 5 mm, preferably 1.3 to 4 mm, more preferably 1.5 to 3 mm, and more preferably 2 to 2.5 mm.

[0144] (Hard rubber layer) In the belt body, it is preferable that a hard rubber layer (or anti-sagging layer) is interposed between the core layer and the compression rubber layer. The interposition of the hard rubber layer properly maintains the alignment of the core wires and improves the belt's resistance to lateral pressure, thereby improving the belt's durability. The hard rubber layer may be formed of a fourth crosslinked rubber composition containing a fourth rubber component and a fourth carbon black.

[0145] (4A) Fourth rubber component The fourth rubber component 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 third rubber component, and more preferably of the same type, in order to improve interlayer adhesion.

[0146] The proportion of the fourth rubber component is 20 to 80% by mass, preferably 30 to 75% by mass, more preferably 35 to 70% by mass, more preferably 40 to 60% by mass, and most preferably 45 to 50% by mass in the fourth crosslinked rubber composition.

[0147] (4B) 4th Carbon Black The fourth carbon black can be selected from the carbon blacks exemplified as the first carbon black, including preferred embodiments.

[0148] In the fourth carbon black, the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount can also be selected from the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount in the first carbon black, including preferred ranges.

[0149] The proportion of the fourth carbon black is, for example, 10 to 100 parts by mass, preferably 30 to 90 parts by mass, more preferably 40 to 80 parts by mass, more preferably 50 to 70 parts by mass, and most preferably 55 to 65 parts by mass, per 100 parts by mass of the fourth rubber component. If the proportion of the fourth carbon black is too low, the lateral pressure resistance may decrease, and if it is too high, the interlayer adhesion may decrease.

[0150] (4C) Fourth plasticizer (or fourth softener) The fourth crosslinked rubber composition preferably further contains a fourth softening agent. The fourth softening agent can be selected from the softening agents exemplified above as the first softening agent, including preferred embodiments. The proportion of the fourth softening agent is, for example, 0.5 to 10 parts by mass, preferably 1 to 7 parts by mass, more preferably 2 to 7 parts by mass, and more preferably 3 to 5 parts by mass, per 100 parts by mass of the fourth rubber component.

[0151] (4D) Fourth crosslinking agent The fourth crosslinked rubber composition preferably further contains a crosslinking agent (fourth crosslinking agent). The fourth crosslinking agent can be selected from the crosslinking agents exemplified as the first crosslinking agent, including preferred embodiments. In the fourth crosslinking agent, the proportion of the fourth crosslinking agent, the proportion of the fourth sulfur-based crosslinking agent, the proportion of the fourth metal oxide, and the mass ratio of the fourth sulfur-based crosslinking agent to the fourth metal oxide can be selected from the respective proportions and mass ratios in the first crosslinking agent, including preferred ranges.

[0152] (4E) Fourth staple fiber The fourth crosslinked rubber composition may further contain a fourth short fiber. Examples of fibers constituting the fourth short fiber include the fibers exemplified as the first short fiber. The fibers can be used alone or in combination of two or more types. Among the fibers, aramid fibers, PBO fibers, and inorganic fibers are preferred, with aramid fibers being particularly preferred, from the viewpoint of improving lateral pressure resistance.

[0153] The average fiber diameter and average fiber length of the fourth short fiber can be selected from the average fiber diameter and average fiber length of the first short fiber, including a preferred range.

[0154] The fourth short fiber may be subjected to conventional bonding treatments from the viewpoint of dispersibility and adhesion of the short fibers in the rubber composition. The adhesive component used for the bonding treatment can be selected from the adhesive components exemplified as adhesive components used for bonding the first short fiber, including preferred embodiments.

[0155] The fourth short fiber may be embedded in the rubber composition (rubber layer) oriented in the belt width direction in order to suppress compressive deformation of the belt due to pressure from the pulley.

[0156] The proportion of the fourth short fibers is, for example, 5 to 50 parts by mass, preferably 10 to 50 parts by mass, more preferably 15 to 40 parts by mass, more preferably 20 to 35 parts by mass, and most preferably 23 to 30 parts by mass, per 100 parts by mass of the fourth rubber component. If the proportion of the fourth short fibers is too low, the lateral pressure resistance may decrease, and if it is too high, the interlaminar adhesion may decrease.

[0157] (4F) 4. Other Additives The fourth crosslinked rubber composition may further contain other additives (fourth other additives). The fourth other additive can be selected from the first other additives, including preferred embodiments. The proportion of the fourth other additive can be selected from a range of proportions of the first other additives, including a preferred range.

[0158] (4G) Characteristics of the fourth crosslinked rubber composition The rubber hardness of the hard rubber layer formed with the fourth crosslinked rubber composition is a type A hardness, which can be selected from a range of approximately 70 to 99, preferably 85 to 98, more preferably 87 to 97, more preferably 90 to 95, and most preferably 92 to 94. If the hardness of the hard rubber layer is too low, the lateral pressure resistance may decrease, and if it is too high, the interlayer adhesion may decrease.

[0159] The fourth crosslinked rubber composition of the hard rubber layer may be the same crosslinked rubber composition as the second crosslinked rubber composition of the second stretchable rubber layer.

[0160] The average thickness of the hard rubber layer is, for example, 0.5 to 5 mm, preferably 0.8 to 3 mm, more preferably 1 to 2 mm, and more preferably 1.3 to 1.8 mm.

[0161] (Compressed rubber layer) The compressed rubber layer may be formed from a fifth crosslinked rubber composition containing a fifth rubber component and a fifth carbon black.

[0162] (5A) Fifth rubber component The fifth rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The fifth rubber component is preferably of the same series or type as the fourth rubber component or the third rubber component (especially the fourth rubber component), and more preferably of the same type, in order to improve interlayer adhesion.

[0163] The proportion of the fifth rubber component is 20 to 80% by mass, preferably 30 to 75% by mass, more preferably 35 to 70% by mass, more preferably 40 to 65% by mass, and most preferably 50 to 60% by mass in the fifth crosslinked rubber composition.

[0164] (5B) 5th Carbon Black The fifth carbon black can be selected from the carbon blacks exemplified as the first carbon black, including preferred embodiments.

[0165] In the fifth carbon black, the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount can also be selected from the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount in the first carbon black, including preferred ranges.

[0166] The proportion of the fifth carbon black is, for example, 10 to 150 parts by mass, preferably 30 to 100 parts by mass, more preferably 40 to 80 parts by mass, and more preferably 50 to 70 parts by mass, per 100 parts by mass of the fifth rubber component. If the proportion of the fifth carbon black is too low, the lateral pressure resistance may decrease, and if it is too high, the interlayer adhesion may decrease.

[0167] (5C) Fifth plasticizer (or fifth softener) The fifth crosslinked rubber composition may further contain a fifth softening agent. The fifth softening agent can be selected from the softening agents exemplified as the first softening agent, including preferred embodiments. The proportion of the fifth softening agent is, for example, 1 to 50 parts by mass, preferably 2 to 30 parts by mass, more 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.

[0168] (5D) Fifth crosslinking agent The fifth crosslinked rubber composition may further contain a fifth crosslinking agent. Examples of the fifth crosslinking agent include the crosslinking agents exemplified above as the first crosslinking agent. The crosslinking agents can be used alone or in combination of two or more. Among the crosslinking agents, metal oxides are preferred.

[0169] The proportion of the fifth crosslinking agent is, for example, 1 to 20 parts by mass, preferably 3 to 18 parts by mass, more preferably 5 to 15 parts by mass, more preferably 6 to 13 parts by mass, and most preferably 7 to 12 parts by mass, per 100 parts by mass of the fifth rubber component.

[0170] (5E) Fifth short fiber The fifth crosslinked rubber composition may further contain fifth short fibers. The fifth short fibers can be selected from the short fibers exemplified as first short fibers, including preferred embodiments. The proportion of fifth short fibers is 30 parts by mass or less, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the fifth rubber component. The fifth crosslinked rubber composition may not contain fifth short fibers.

[0171] (5F) 5th Other Additives The fifth crosslinked rubber composition may further contain other additives (fifth other additives). The fifth other additive can be selected from the first other additives, including preferred embodiments. The proportion of the fifth other additive can be selected from a range of proportions of the first other additives, including a preferred range.

[0172] (5G) Properties of the 5th Crosslinked Rubber Composition The rubber hardness of the compressed rubber layer formed with the fifth crosslinked rubber composition is, for example, 60 to 85, preferably 65 to 82, more preferably 70 to 80, and even more preferably 73 to 77, on a Type A hardness scale.

[0173] The average thickness of the compressed rubber layer is, for example, 1 to 10 mm, preferably 1.5 to 5 mm, more preferably 2 to 4 mm, and more preferably 2.5 to 3.5 mm.

[0174] (Reinforcement fabric layer) The belt body may, if necessary, include a reinforcing fabric layer laminated on the inner circumferential surface (inner surface) of the compression rubber layer. In this invention, by laminating the reinforcing fabric layer on the inner circumferential side of the compression rubber layer, the flexibility of the belt can be ensured while increasing its resistance to lateral pressure and improving its durability. On the other hand, if the reinforcing fabric layer is not laminated, the flexibility of the belt may decrease and heat generation may increase.

[0175] The reinforcing fabric layer may be formed from, for example, conventional fabric (fabric material or cloth), and examples of fabric include woven fabrics, knitted fabrics (weft knitted fabrics, warp knitted fabrics), and nonwoven fabrics. Of these, woven fabrics produced in forms such as plain weave, twill weave, and satin weave, woven fabrics and knitted fabrics produced with a wide angle where the intersection angle between the warp and weft threads exceeds 90° and is about 120° or less are preferred, and woven fabrics commonly used as cover fabrics for transmission belts in general industrial and agricultural machinery [plain weave fabrics where the intersection angle between the warp and weft threads is right angle, and plain weave fabrics where the intersection angle between the warp and weft threads exceeds 90° and is about 120° or less (wide-angle canvas)] are particularly preferred. Furthermore, for applications where durability is required, wide-angle canvas may also be used.

[0176] Furthermore, from the viewpoint of flexibility, it is preferable that the warp and weft threads of the woven fabric be arranged so that their extension directions intersect with the belt length direction. The warp and weft threads may also be arranged so that their directions are, for example, 45 to 75° (for example, 50 to 70°), preferably about 55 to 65°, with respect to the belt length direction.

[0177] Examples of fibers constituting the fabric include those exemplified as fibers constituting the first short fibers. The yarn constituting the fabric may be a single yarn using only the fibers exemplified as fibers constituting the first short fibers, or it may be a blended yarn combining two or more types. From the viewpoint of excellent mechanical properties and economic efficiency, a blended yarn of polyester fibers and cellulosic fibers is preferred for the yarn constituting the fabric.

[0178] Polyester fibers may also be polyalkylene arylate fibers. Examples of polyalkylene arylate fibers include polyethylene terephthalate (PET) fibers, polyethylene naphthalate (PEN) fibers, and other polycrystalline C 2-4 Alkylene-C 8-14 Examples include arylate-based fibers.

[0179] Cellulosic fibers can be selected from the exemplified cellulose fibers as first short fibers, including preferred embodiments.

[0180] The mass ratio of polyester fibers to cellulose fibers is, for example, 90 / 10 to 10 / 90, preferably 80 / 20 to 20 / 80, and more preferably 70 / 30 to 30 / 70 (especially 60 / 40 to 40 / 60).

[0181] The average fineness of the yarns that make up the fabric is, for example, 5 to 30 count, preferably 10 to 25 count, and more preferably 15 to 25 count.

[0182] The basis weight of the fabric (raw material) is, for example, 100-500 g / m². 2 Preferably 200-400 g / m² 2 More preferably 250-300 g / m²2 It is to that extent.

[0183] If the fabric (raw material) is woven, the thread density of the fabric (warp density, weft density) is, for example, 60 to 100 threads / 50 mm, preferably 65 to 90 threads / 50 mm, and more preferably 70 to 80 threads / 50 mm.

[0184] The fabric forming the reinforcing fabric layer may be subjected to conventional bonding treatment (or surface treatment) [for example, treatment with a treatment solution containing an adhesive component] to improve adhesion to the compression rubber layer and the outer fabric. The adhesive component used for bonding treatment can be selected from the adhesive components exemplified as adhesive components used for bonding treatment of the first short fibers, including preferred embodiments.

[0185] Furthermore, the fabric may be subjected to an adhesive treatment that involves attaching a rubber component. For example, the fabric may be soaked in a rubber glue made by dissolving a rubber composition containing a rubber component in a solvent, or a solid rubber composition may be rubbed into the fabric. Of these adhesive components, a rubber component, RFL liquid, or a combination thereof is preferred. The adhesive treatment only needs to be applied to at least one surface of the fabric, but it is preferable to treat both surfaces.

[0186] (Sixth crosslinked rubber composition) The crosslinked rubber composition used for bonding fabrics and constituting the reinforcing fabric layer may be a sixth crosslinked rubber composition containing a sixth rubber component.

[0187] (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 fifth rubber component, and more preferably of the same type, in order to improve interlayer adhesion.

[0188] The proportion of the sixth rubber component is 20 to 80% by mass, preferably 30 to 75% by mass, more preferably 35 to 70% by mass, more preferably 40 to 65% by mass, and most preferably 50 to 60% by mass in the sixth crosslinked rubber composition.

[0189] (6B) 6th Carbon Black The sixth crosslinked rubber composition may further contain a sixth carbon black. The sixth carbon black can be selected from the carbon blacks exemplified as the first carbon black, including in preferred embodiments.

[0190] In the sixth carbon black, the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount can also be selected from the range of soft carbon black proportion, iodine adsorption amount, BET specific surface area, and DBP absorption amount in the first carbon black, including preferred ranges.

[0191] The proportion of the sixth carbon black is, for example, 10 to 150 parts by mass, preferably 20 to 100 parts by mass, more preferably 30 to 80 parts by mass, and more preferably 40 to 60 parts by mass, per 100 parts by mass of the sixth rubber component. If the proportion of the sixth carbon black is too low, the lateral pressure resistance may decrease, and if it is too high, the adhesion to the outer fabric and the compression rubber layer may decrease.

[0192] (6C) Sixth softener (or sixth plasticizer) The sixth crosslinked rubber composition may further contain a sixth softening agent. The sixth softening agent can be selected from the softening agents exemplified as the first softening agent, including preferred embodiments. The proportion of the sixth softening agent 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 20 parts by mass, per 100 parts by mass of the sixth rubber component.

[0193] (6D) Crosslinking agent #6 The sixth crosslinked rubber composition may further contain a sixth crosslinking agent. Examples of the sixth crosslinking agent include the crosslinking agents exemplified above as the first crosslinking agent. The crosslinking agents can be used alone or in combination of two or more. Among the crosslinking agents, metal oxides are preferred.

[0194] The proportion of the sixth crosslinking agent is, for example, 1 to 20 parts by mass, preferably 3 to 18 parts by mass, more preferably 5 to 15 parts by mass, more preferably 6 to 13 parts by mass, and most preferably 7 to 12 parts by mass, per 100 parts by mass of the sixth rubber component.

[0195] (6E) Sixth short fiber The sixth crosslinked rubber composition may further contain sixth short fibers. The sixth short fibers can be selected from the short fibers exemplified as first short fibers, including preferred embodiments. The proportion of sixth short fibers is 30 parts by mass or less, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the sixth rubber component. The sixth crosslinked rubber composition may not contain sixth short fibers.

[0196] (6F) 6. Other Additives The sixth crosslinked rubber composition may further contain other additives (sixth other additives). The sixth other additive can be selected from the first other additives, including preferred embodiments. The proportion of the sixth other additive can be selected from the proportion range of the first other additives, including preferred ranges.

[0197] (6G) Characteristics of the sixth crosslinked rubber composition and reinforcing fabric layer The rubber hardness of the sixth crosslinked rubber composition is, for example, 60 to 85, preferably 65 to 82, more preferably 70 to 80, and more preferably 73 to 77, on a Type A hardness scale.

[0198] The basis weight of the fabric after adhesive treatment (treated fabric) is, for example, 300-800 g / m². 2 Preferably 400-600 g / m² 2 More preferably 450-550 g / m² 2 That is the case.

[0199] The reinforcing fabric layer may be a single layer or a laminated structure such as a double layer. Of these, a single layer or a double layer is preferred, and a double layer is particularly preferred.

[0200] The average thickness of the reinforcing fabric layer (or the average thickness of each layer in the case of a multilayer structure) is, for example, 0.3 to 2 mm, preferably 0.4 to 1.5 mm, more preferably 0.45 to 1 mm, and more preferably 0.5 to 0.7 mm.

[0201] [Outer cover] The outer covering (cover fabric) is made of a conventional fabric. The fabric can be selected from the fabrics exemplified in the reinforcing fabric layer, including preferred embodiments.

[0202] The fabric forming the outer cover may be subjected to conventional bonding treatment (or surface treatment) [for example, treatment with a treatment solution containing an adhesive component] to improve adhesion to the belt body. The adhesive component used for bonding treatment can be selected from the adhesive components exemplified as adhesive components used for bonding treatment of the first short fibers, including preferred embodiments.

[0203] Furthermore, the fabric may be subjected to an adhesive treatment that involves attaching a rubber component. For example, the fabric may be soaked in a rubber glue made by dissolving a rubber composition containing a rubber component in a solvent, or a solid rubber composition may be rubbed into the fabric.

[0204] The cross-linked rubber composition used for bonding the fabric and constituting the outer covering fabric may be a seventh cross-linked rubber composition containing a seventh rubber component. The seventh cross-linked rubber composition can be selected from the sixth cross-linked rubber composition, including preferred embodiments. The bonding treatment only requires treating at least one surface of the fabric, and it is preferable to treat at least the surface (especially both sides) that comes into contact with the belt body.

[0205] The basis weight of the fabric after adhesive treatment (treated fabric) is, for example, 300-800 g / m². 2 Preferably 400-600 g / m² 2 More preferably 450-550 g / m²2 That is the case.

[0206] The average thickness of the outer covering fabric (or the average thickness of each layer in the case of a multilayer structure) is, for example, 0.3 to 2 mm, preferably 0.4 to 1.5 mm, more preferably 0.45 to 1 mm, and more preferably 0.5 to 0.7 mm. If the thickness of the outer covering fabric is too thin, the abrasion resistance may decrease, and if it is too thick, the flexibility of the belt may decrease.

[0207] The outer covering only needs to cover the inner circumference and both sides of the belt, and may be a single layer formed from one piece of outer covering. From the viewpoint of easily improving abrasion resistance, it may also be a multilayer or multiple-layer structure (for example, 2 to 5 layers, preferably 2 to 4 layers, more preferably 2 to 3 layers, especially 2 layers) formed by laminating multiple pieces of outer covering. However, from the viewpoint of productivity and resistance to lateral pressure, 1 to 3 layers [for example, a single layer (1 ply) or 2 layers (2 ply)] is preferred, and from the viewpoint of a good balance between productivity, abrasion resistance and resistance to lateral pressure, and excellent durability, 2 to 3 layers are more preferred, and 2 layers are particularly preferred. If there are too many layers of outer covering fabric, productivity is likely to decrease, and lateral pressure resistance may also decrease (and consequently, durability may decrease). If there are too few layers, when manufacturing according to the manufacturing method described later, areas that are not covered by the outer covering fabric are likely to occur on the belt side (transmission surface) during the covering process (rubber is likely to be exposed from the side), which may not only decrease productivity and wear resistance, but also cause rubber to seep out or be exposed from the worn outer covering fabric during belt operation, which may increase the coefficient of friction with the pulley and generate heat (reducing the adhesive strength between the wrapped V-belt and the tie band due to the heat), thus reducing durability.

[0208] If the outer covering consists of multiple layers (a form in which multiple outer coverings are stacked), each of the multiple outer coverings may cover the same or different areas on the inner circumference and both sides of the belt body, thereby forming a covered area. Furthermore, it is not necessary for all of the multiple layers of outer coverings to cover the inner circumference and both sides; it is sufficient if at least one layer of outer coverings covers the inner circumference and both sides.

[0209] The outer covering fabric that covers the inner circumference and both sides of the belt is formed to extend in the length direction of the belt, and is preferably a single continuous piece of fabric that can cover the entire length of the belt.

[0210] In this application, a seamless or continuous cloth (outer covering cloth or outer covering cloth precursor) means that, in the state before the covering process (or as an outer covering cloth precursor), it is a single piece of cloth that can be independently wound up, and may have joints (connecting parts), for example, including cloths in which the ends of two or more cloths are joined (connected) or partially overlapped and joined.

[0211] [Tie band (connecting member)] As the tie band, conventional tie bands for bonded V-belts can be used, and examples include rubber compositions (crosslinked rubber compositions containing rubber components), woven fabrics such as canvas, bamboo blinds (bamboo blind fabrics), nets (mesh structures or meshes), and combinations thereof. It is preferable that the tie band contains at least fibers in order to effectively suppress ring breakage of the wrapped bonded V-belt.

[0212] When tie bands contain fibers, the adhesive strength (peel strength) with the wrapped V-belt portion is usually prone to decrease. However, in the wrapped bonded V-belt of the present invention, the stretchable rubber layer is exposed on the outer surface of the wrapped V-belt portion, ensuring high adhesive strength. This allows for both high adhesion and resistance to ring breakage, effectively improving the durability of the wrapped bonded V-belt.

[0213] The tie band containing fibers may be, for example, a rubber composition containing short fibers, but it is preferable that it contains at least a fiber structure. Therefore, the tie band may have at least a connecting reinforcement layer containing a fiber structure, and may optionally have a protective layer laminated on the outer periphery of the connecting reinforcement layer.

[0214] (Connecting reinforcement layer) The connecting reinforcement layer only needs to include at least the aforementioned fiber structure (or fabric). Examples of fiber structures include bamboo blind fabric, woven fabric, mesh fabric, net (mesh structure or mesh), knitted fabric, and nonwoven fabric. These fiber structures can be used individually or in combination of two or more. Of these, woven fabrics or fabrics having a weave structure such as bamboo blind weave or plain weave are preferred because they can achieve both resistance to ring breakage and flexibility in the longitudinal direction of the belt, and also have an excellent balance with productivity. Bamboo blind fabric is particularly preferred because rubber can easily penetrate between the threads, improving adhesion to the stretchable rubber layer and improving durability.

[0215] Among the various types of woven bamboo blinds, those containing multiple thread-like bodies extending in the belt width direction are preferred because they can further improve resistance to tensile force acting in the belt width direction. In particular, it is preferable to use a woven bamboo blind that contains multiple first thread-like bodies (yarn-like bodies) extending in the belt width direction and multiple second thread-like bodies that have a lower thread density (arrangement density) than the multiple first thread-like bodies and extend in a direction intersecting the belt width direction.

[0216] In this application, the filamentous material extending in the belt width direction means a filamentous material extending substantially parallel to the belt width direction. Furthermore, "substantially parallel" means that the angle between the direction in which the filamentous material extends and the belt width direction is, for example, 10° or less (e.g., 0 to 5°), preferably 3° or less (e.g., 0 to 1°, especially approximately 0°).

[0217] The thread density of the first filamentous material (number of threads per 5 cm in the belt length direction) is, for example, 10 to 300 threads / 50 mm, preferably 50 to 200 threads / 50 mm, more preferably 80 to 180 threads / 50 mm, more preferably 100 to 150 threads / 50 mm, and most preferably 110 to 130 threads / 50 mm.

[0218] The thread density of the second filamentous structure is, for example, 1 to 30 threads / 50 mm, preferably 2 to 10 threads / 50 mm, more preferably 2 to 8 threads / 50 mm, more preferably 3 to 7 threads / 50 mm, and most preferably 4 to 6 threads / 50 mm.

[0219] The thread density of the first thread state is, for example, 2 to 100 times, preferably 5 to 80 times, more preferably 10 to 50 times, more preferably 15 to 40 times, and most preferably 20 to 30 times, compared to the thread density of the second filamentous body.

[0220] Furthermore, in this application, a bamboo blind fabric means a woven fabric formed of a plurality of first filamentous bodies and a plurality of second filamentous bodies, wherein the first filamentous bodies and the second filamentous bodies have a range of yarn density. For example, it may be a woven fabric consisting of warp threads and weft threads with a lower yarn density than the warp threads.

[0221] Examples of fibers constituting the first and second filamentous bodies include the fibers exemplified as constituting the first short fibers. The first and second filamentous bodies may be single yarns using the fibers exemplified as constituting the first short fibers individually, or they may be blended yarns combining two or more types.

[0222] Of the aforementioned fibers, polyester fibers and polyamide fibers are preferred as the first filamentous body, and aliphatic polyamide fibers are particularly preferred.

[0223] Examples of aliphatic polyamide fibers include polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers, polyamide 11 fibers, and polyamide 12 fibers. Of these, polyamide 6 fibers and polyamide 66 fibers are preferred.

[0224] Of the aforementioned fibers, cellulose fibers are preferred as the second filamentous body.

[0225] Cellulosic fibers can be selected from the exemplified cellulose fibers as first short fibers, including preferred embodiments.

[0226] When the first filamentous material is formed from polyester fibers or polyamide fibers, the fineness of the first filamentous material (or total fineness in the case of a multifilament yarn, etc.) is, for example, 100 to 1000 dtex, preferably 200 to 800 dtex, and more preferably 400 to 600 dtex.

[0227] When the second filamentous body is formed from cellulose fibers such as cotton fibers, the thickness (count) of the second filamentous body is, for example, 5 to 100 count, preferably 10 to 80 count, and more preferably 30 to 50 count.

[0228] The fiber structure may be subjected to conventional bonding treatments (or surface treatments) [for example, treatment with a treatment solution containing an adhesive component] to improve its adhesion to rubber components (crosslinked rubber compositions), etc. The adhesive component used for the bonding treatment can be selected from the adhesive components exemplified as adhesive components used for bonding treatment of the first short fibers, including preferred embodiments.

[0229] The average thickness of the fiber structure is, for example, 0.1 to 0.5 mm, preferably 0.2 to 0.4 mm. If the fiber structure is too thin, there is a risk of delamination or ring breakage, and if it is too thick, there is a risk of reduced belt flexibility.

[0230] The connecting reinforcement layer may be formed of a fibrous structure (for example, a cloth treated with adhesive such as a rubber component), but in addition to suppressing peeling of the fibrous structure, it is preferable that the fibrous structure be sandwiched between rubber compositions containing the eighth rubber component (connecting reinforcement layer sandwiching rubber) (in which case the fibrous structure is embedded in the eighth crosslinked rubber composition) from the viewpoint of suppressing interlayer (interlayer with the wrapped V-belt portion and / or protective layer) peeling and ring breakage (including suppression of defect propagation). The eighth crosslinked rubber composition can be selected from the sixth crosslinked rubber composition, including the preferred embodiment.

[0231] The connecting reinforcement layer can be used alone (single layer) or in combination of two or more types, but it is preferable to use it alone (single layer).

[0232] The average thickness of the connecting reinforcement layer is, for example, 0.4 to 1.4 mm, preferably 0.5 to 1 mm. If the connecting reinforcement layer is too thin, there is a risk of delamination or ring breakage, and if it is too thick, there is a risk of reduced belt flexibility.

[0233] (protective layer) The tie band (connecting member) may be formed solely of the connecting reinforcement layer, but it may also be equipped with a protective layer laminated on top of the connecting reinforcement layer (on the outer surface side of the belt or the outermost layer) in order to effectively suppress damage to the fibrous structure in the connecting reinforcement layer (for example, damage caused by foreign matter from the back of the belt).

[0234] The protective layer may be formed from a rubber sheet of a conventional crosslinked rubber composition (e.g., a rubber sheet of a first crosslinked rubber composition) or from a conventional fabric (e.g., the fabric exemplified as the fabric for the outer covering). The fabric may be bonded, and bonded treatments to the outer covering can be selected, including preferred embodiments. These protective layers can be used alone or in combination of two or more. Of these protective layers, a protective layer formed from fabric is preferred in terms of ease of handling and productivity.

[0235] The average thickness of the protective layer is, for example, 0.3 to 2 mm, preferably 0.4 to 1.5 mm, more preferably 0.45 to 1 mm, and more preferably 0.5 to 0.7 mm. If the protective layer is too thin, the effect of suppressing damage to the fiber structure may decrease, and if it is too thick, the flexibility of the belt may decrease.

[0236] The tie band (connecting member) may have multiple protective layers (e.g., 2 to 3 layers) as needed, but preferably has one layer.

[0237] [Manufacturing method for wrapped V-belts] A wrapped V-belt is obtained by first manufacturing uncrosslinked (unvulcanized) wrapped V-belt sections (wrapped V-belt section precursors), and then connecting multiple obtained uncrosslinked wrapped V-belt sections (wrapped V-belt section precursors) with tie bands (tie band precursors).

[0238] Uncrosslinked (unvulcanized) wrapped V-belt sections (wrapped V-belt section precursors) can be manufactured, for example, by the methods described in Japanese Patent Publication No. 6-137381 and in brochure WO2015 / 104778. Specifically, the process involves a winding step in which an uncrosslinked sheet for the compression rubber layer obtained by rolling is cut and set in the mantle, an uncrosslinked first adhesive rubber layer sheet is wrapped around the outer circumference of the compression rubber layer sheet, a core is wrapped around the outer circumference of the wrapped first adhesive rubber layer sheet, and then an uncrosslinked second adhesive rubber layer sheet and an uncrosslinked stretchable rubber layer sheet are wrapped around the outer circumference of the wrapped core in that order; a cutting step in which the resulting annular laminate is cut (sliced) on the mantle; a skiving step (skiving process) in which the cut annular laminate is placed on a pair of pulleys and cut into a V shape while rotating; and an outer covering step (covering process or cover winding process) in which the inner circumferential surface and both sides of the obtained uncrosslinked belt body (belt body precursor) are covered with an outer covering precursor [for example, an outer covering (cloth) to which an uncrosslinked rubber composition is attached], thereby obtaining an uncrosslinked wrapped V-belt (wrapped V-belt precursor).

[0239] Furthermore, when forming the reinforcing fabric layer, hard rubber layer, and second stretchable rubber layer in the winding process, an uncrosslinked wrapped V-belt section can be obtained by winding the reinforcing fabric layer precursor, hard rubber layer sheet, and second stretchable rubber layer sheet, respectively. In addition, only one of the first and second adhesive rubber layer sheets may be wound, or neither may be wound (the adhesive rubber layer may not be formed). Furthermore, even if the stretchable rubber layer has a single-layer structure, it may be manufactured by winding multiple sheets of the same stretchable rubber layer.

[0240] The present invention provides a method for manufacturing a wrapped bonded V-belt, comprising at least a coating step of covering a belt body precursor with an outer covering precursor to form a wrapped V-belt precursor, and a connecting step of connecting the outer circumferential surfaces of a plurality of wrapped V-belt precursors obtained in the coating step with a tie band precursor [for example, a tie band containing fibers (particularly a fiber structure) and an uncrosslinked rubber composition], wherein the coating step covers the inner circumferential surface and both sides of the belt body precursor, but does not cover the outer circumferential surface, and does not require a removal step (a step described in Patent Documents 2-3) of cutting or removing the outer covering precursor that covers the outer circumferential surface of the wrapped V-belt precursor obtained in the coating step. Therefore, a process can be omitted, and a wrapped bonded V-belt with excellent abrasion resistance and suppressed peeling of the tie bands can be manufactured inexpensively and with high productivity.

[0241] In the coating process, the inner circumferential surface and both sides of the belt body precursor may be coated with at least a continuous outer covering precursor. The width of the outer covering precursor may be shorter than the perimeter of the cross-sectional shape perpendicular to the length direction of the belt body precursor (i.e., the sum of the dimensions of the inner circumferential surface, both sides, and the outer circumferential surface in the cross-sectional shape), or it may be longer than the sum of the dimensions of the inner circumferential surface and both sides in the cross-sectional shape, depending on the area ratio of the uncoated area. The belt body precursor may be coated with the width direction of the outer covering precursor oriented perpendicular to the length direction of the belt (the length direction of the outer covering precursor oriented in the length direction of the belt).

[0242] In conventional methods, when covering a belt body precursor with an outer covering precursor, for example as shown in Figure 2, the belt body precursor is wrapped around two pulleys and rotated (runs), and the outer covering precursor, wound in a roll shape, is fed out and brought into contact with the outer surface of the rotating belt body precursor. The outer covering precursor that is in contact with the outer surface is then pressed against a roller so as to conform to the shape of the belt body precursor (while feeding out the outer covering precursor, the roller is applied from the outside to roll it into a cylindrical shape like a pipe conveyor, enveloping the belt body precursor), and the outer covering precursor is overlapped on the inner circumference to form a wrapped V-belt precursor.

[0243] In contrast, the present invention allows the belt body precursor to be rotated (run) between two pulleys with its inner and outer circumferences reversed from the conventional method (with the wider side facing the inner circumference and the narrower side facing the outer circumference), and then covered with an outer covering precursor of a predetermined width. Specifically, the outer covering precursor of a predetermined width is brought into contact with the narrower outer surface of the rotating belt body precursor (the surface that will become the inner circumference of the wrapped V-belt portion), and pressed with a roller to conform to the shape of the belt body precursor in the same manner as in the conventional method, thereby covering both sides and forming a wrapped V-belt portion precursor in which only the inner surface and both sides are covered with the outer covering.

[0244] When covering with an endless outer covering precursor without any breaks, one end of the outer covering precursor in the longitudinal direction may be adjacent to the other without overlapping, or they may be partially overlapped, and preferably both ends in the longitudinal direction may be partially overlapped to cover in an endless manner.

[0245] The wrapped V-belt precursors obtained in the coating process can be connected to tie band precursors (e.g., tie bands containing an uncrosslinked rubber composition) by a conventional method (connecting process). For example, after multiple uncrosslinked wrapped V-belts (wrapped V-belt precursors) are fitted into a trapezoidal groove formed in a cylindrical or annular lower crosslinking mold, tie band precursors are set on the radially outer portion. In setting the tie band precursors, the tie band precursors are wrapped around multiple uncrosslinked wrapped V-belts arranged in the width direction along the circumferential direction. The tie band precursors and multiple uncrosslinked wrapped V-belts (wrapped V-belt precursors) set as described above are subjected to a crosslinking molding process (vulcanization process) [crosslinking molding process (vulcanization process)] in which they are sandwiched between an upper crosslinking mold and a lower crosslinking mold and crosslinked or vulcanized while under pressure. This crosslinking molding process (vulcanization process) forms a crosslinked sleeve (vulcanized sleeve) in which multiple wrapped V-belts are connected and joined by tie bands. The cross-linked sleeve (vulcanized sleeve) formed in this manner is cut to a predetermined width to form a wrapped bonded V-belt having a predetermined number of wrapped V-belt sections.

[0246] In the crosslinking molding process (vulcanization process), the crosslinking (vulcanization) temperature can be selected according to the type of rubber component, for example, 120 to 200°C, preferably around 150 to 180°C. The pressure in the crosslinking molding process (vulcanization process) may be, for example, 1 to 2 MPa, preferably 1 to 1.5 MPa. Each rubber layer sheet containing short fibers can be rolled using a calender roll or similar method to arrange (orient) the short fibers in the rolling direction.

[0247] Furthermore, the tie band precursor and each uncrosslinked (unvulcanized) wrapped V-belt portion (wrapped V-belt portion precursor) are bonded to each other, for example, by adhesive components attached to the tie band precursor by an adhesive treatment, and by the exposed stretchable rubber layer. For example, if a cloth that has been treated with a friction (rubbing) solid rubber composition is used as the tie band, the tie band precursor and the exposed stretchable rubber layer are bonded to each other by the crosslinking (vulcanization) reaction of the friction rubber composition. In other words, the step of setting the tie band precursor to the uncrosslinked wrapped V-belt portion includes an uncrosslinked (unvulcanized) belt bonding step in which multiple uncrosslinked wrapped V-belt portions are bonded to each other via the tie band precursor as a connecting portion. The uncrosslinked belt bonding step is not limited to this method, and the tie band precursor may be constructed by wrapping multiple layers of rubber sheets for tie bands (e.g., sheets for connecting reinforcement layers, sheets for protective layers, laminates thereof, etc.).

[0248] The number of wrapped V-belt sections in a wrapped V-belt is two or more, for example, 2 to 10, preferably 2 to 8, and more preferably 2 to 6. Adjacent wrapped V-belt sections only need to be aligned parallel to the length of the belt, and are not limited to being spaced apart as shown in Figure 4, but may be arranged without spacing. From the viewpoint of productivity, it is preferable to space adjacent wrapped V-belt sections. The spacing between adjacent wrapped V-belt sections is, for example, 1.7 to 4.3 mm, preferably 2 to 4.1 mm, and more preferably about 2.3 to 3.9 mm. Note that the spacing between wrapped V-belt sections refers to the spacing on the outer surface of the belt. The tie band only needs to be able to connect each wrapped V-belt section, and is not limited to being connected by contacting and integrating the entire outer surface of each wrapped V-belt section as shown in Figure 4, but may have areas where the outer surface of the wrapped V-belt section does not contact the tie band. From the standpoint of belt durability, it is preferable that the entire outer surface of each wrapped V-belt section contacts and integrates with the tie band.

[0249] Wrapped V-belts may be used in high-load, long-span (long-distance between shafts) layouts such as those of large-scale agricultural machinery. The width of the outer surface of each wrapped V-belt section may be, for example, about 15 to 60 mm, and the thickness of each wrapped V-belt section may be, for example, 10 to 20 mm (for example, 10 to 15 mm).

[0250] The total length of the wrapped V-belt may be, for example, 50 inches or more, 200 inches (508 cm) or more, or approximately 220 to 500 inches.

[0251] Wrapped V-belts are suitable for long-span layouts, and the maximum span length (distance between pulleys) can be 1000 mm or more, for example, around 2000 to 5000 mm.

[0252] The wrapped V-belt of the present invention is suitable for high-load applications and is therefore suitable for high-horsepower machinery. The load on a single wrapped V-belt section (reference transmission capacity) may be 10 PS or more, preferably 20 PS or more, and more preferably 22 PS or more (for example, around 22 to 30 PS).

[0253] The wrapped V-belt of the present invention exhibits excellent adhesion (tightness) between the wrapped V-belt portion and the tie band. The peel force (or adhesive strength) between the wrapped V-belt portion and the tie band is, for example, 50 to 150 N / cm, preferably 60 to 130 N / cm, preferably 70 to 125 N / cm, more preferably 80 to 122 N / cm, more preferably 90 to 120 N / cm, and most preferably 95 to 120 N / cm at 23°C. Furthermore, the peel force at high temperatures is also high, with the peel force at 150°C being, for example, 10 to 100 N / cm, preferably 20 to 80 N / cm, more preferably 25 to 60 N / cm, and more preferably 30 to 50 N / cm.

[0254] In this application, the peeling force (or adhesive strength) between the wrapped V-belt portion and the tie band can be measured by the method described in the examples.

Example

[0255] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples. In addition, the raw materials and preparation methods of the rubber composition, core wire, outer cover cloth precursor, and connecting reinforcing layer precursor used below, the preparation method of the belt, and the measurement method or evaluation method are shown.

[0256] <Examples 1 to 12 and Comparative Examples 1 to 4> [Rubber Composition] (Materials Used) Chloroprene rubber: "PM-40" manufactured by Denka Co., Ltd. Cotton staple fiber: "Cotton Cut Thread" manufactured by Hashimoto, average fiber length 6 mm Nylon staple fiber: "Leona" manufactured by Asahi Kasei Corporation, average fiber diameter 27 μm, fiber length 3 mm Aramid staple fiber: "Twaron (registered trademark)" manufactured by Teijin Limited, fiber length 3 mm Stearic acid: "Stearic Acid Camellia" manufactured by NOF Corporation Zinc oxide: "Zinc Oxide No. 2" manufactured by Sakai Chemical Industry Co., Ltd. Carbon black FEF: "Seast SO" manufactured by Tokai Carbon Co., Ltd., DBP absorption 115 mL / 100 g, BET specific surface area 42 m 2 / g, iodine adsorption 44 g / kg, average primary particle diameter 43 nm Carbon black HAF: "Seast 3" manufactured by Tokai Carbon Co., Ltd., DBP absorption 101 mL / 100 g, BET specific surface area 79 m 2 / g, iodine adsorption 80 g / kg, average primary particle diameter 28 nm Silica: "Ultrasil VN3" manufactured by Evonik Industries AG, BET specific surface area 180 m 2 / g Magnesium oxide: "Kyowa Mag 150" manufactured by Kyowa Chemical Industry Co., Ltd. Softening agent A: "ADEKA Sizer C-8" manufactured by ADEKA Corporation Antioxidant ODPA (octyldiphenylamine): "Nonflex OD-3" manufactured by Seiko Chemical Co., Ltd. Crosslinking accelerator MBTS (2,2'-dibenzothiazolyl disulfide): "Noxellar DM" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfur (powdered sulfur): Manufactured by Bigen Chemical Co., Ltd.

[0257] (Preparation of uncrosslinked rolled rubber sheets and bulk uncrosslinked rubber compositions for friction) The rubber composition R1 shown in Table 1 was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce an uncrosslinked (unvulcanized) rolled rubber sheet of a predetermined thickness, which was used as a sheet for a compression rubber layer or a sheet for a hard rubber layer.

[0258] The rubber composition R2 shown in Table 1 was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce an uncrosslinked (unvulcanized) rolled rubber sheet of a predetermined thickness, which was used as the sheet for the adhesive rubber layer (inner and outer circumference of the core wire).

[0259] The rubber composition R3 shown in Table 1 was mixed in a Banbury mixer to prepare a bulk, uncrosslinked (unvulcanized) rubber composition for friction to form an outer covering precursor or reinforcing fabric layer precursor.

[0260] The rubber composition R3 shown in Table 1 was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce an uncrosslinked (unvulcanized) rolled rubber sheet of a predetermined thickness, which was used as a sheet for the connecting reinforcement layer.

[0261] The rubber composition R4 shown in Table 2 was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce an uncrosslinked (unvulcanized) rolled rubber sheet of a predetermined thickness, which was used as a protective layer sheet or a stretchable rubber layer sheet.

[0262] The rubber composition R5, as shown in Table 2, was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce uncrosslinked (unvulcanized) rolled rubber sheets of a predetermined thickness, which were then used as sheets for hard rubber layers or stretchable rubber layers.

[0263] Rubber compositions R6 to R12, as shown in Table 2, were mixed in a Banbury mixer. These mixed rubbers were then passed through a calender roll to produce uncrosslinked (unvulcanized) rolled rubber sheets of a predetermined thickness, which were used as sheets for stretched rubber layers.

[0264] Furthermore, the short fibers contained in the uncrosslinked rubber sheet were oriented in the rolling direction.

[0265] [Table 1]

[0266] [Table 2]

[0267] [Rubber hardness of cross-linked rubber] Uncrosslinked rubber compositions having the compositions shown in Tables 1 and 2 were passed through a calender roll to prepare uncrosslinked rolled rubber sheets of a predetermined thickness. The obtained uncrosslinked rolled rubber sheets were then press-heated at a temperature of 153°C, 2 MPa, and for 20 minutes to produce crosslinked rubber sheets (100 mm × 100 mm × 2 mm thickness). A laminate of three crosslinked rubber sheets was used as a sample, and the rubber hardness (Type A) of the crosslinked rubber sheets was measured using a Type A durometer in accordance with the spring-type durometer hardness test specified in JIS K 6253 (2012) (Vulcanized rubber and thermoplastic rubber - Method for determining hardness -). The test temperature was 23°C.

[0268] [Core wire (processing code)] Three bundles of 1670 dtex (1000 filaments) aramid fibers were joined together and twisted in the S direction with a twist coefficient of 3.0 to produce a base twist yarn. Five of these base twist yarns were then joined together and twisted in the Z direction with a twist coefficient of 3.0 to produce a twisted cord (multi-twisted yarn) with a total fineness of 25050 dtex (15000 filaments) and a diameter of 1.9 mm. This treated cord was then bonded and used as the core wire. The twist coefficient TF is calculated using the following formula.

[0269] TF = TN × D 0.5 / 960 [In the formula, TF represents the twist coefficient, TN represents the number of twists per meter, and D represents the yarn fineness (tex).]

[0270] [Outer covering fabric precursor, reinforcing fabric layer precursor or protective layer precursor (treated canvas)] For the outer covering fabric precursor, reinforcing fabric layer precursor or protective layer precursor, a canvas (treated canvas) subjected to adhesion treatment and friction was used. That is, using a blended yarn of 20s / 3 (20 count 3 - ply twist) obtained by blending polyester fiber and cotton at a mass ratio of 50 / 50 as warp and weft, plain - woven with a warp density of 75 threads / 50 mm and a weft density of 75 threads / 50 mm, and a basis weight of 280 g / m 2 of canvas was immersed in an RFL solution (a mixed solution of 2.6 parts by mass of resorcinol, 1.4 parts by mass of 37% formalin, 17.2 parts by mass of vinyl pyridine - styrene - butadiene copolymer latex (manufactured by Nippon Zeon Co., Ltd.), and 78.8 parts by mass of water), dried, and then subjected to a wide - angle treatment so that the angle formed by the warp and weft was 120 degrees. A treatment (friction) of rubbing the rubber composition R3 into both the front and back surfaces of the obtained wide - angle canvas was performed to obtain a treated canvas (basis weight of about 500 g / m 2 , thickness of about 0.6 mm) was used.

[0271] [Connecting reinforcing layer precursor (treated reed)] The reed was subjected to adhesion treatment and rubber sheet lamination treatment to obtain a connecting reinforcing layer precursor. Specifically, using a single - twist cord made of nylon 66 with a fineness of 470 dtex (wire diameter of 0.22 mm) as the warp and a 40 - count cotton yarn (wire diameter of 0.1 mm) as the weft, a reed - shaped fabric woven with a warp density of 120 threads / 50 mm and a weft density of 5 threads / 50 mm was immersed in an RFL solution (a mixed solution of 2.6 parts by mass of resorcinol, 1.4 parts by mass of 37% formalin, 17.2 parts by mass of vinyl pyridine - styrene - butadiene copolymer latex (manufactured by Nippon Zeon Co., Ltd.), and 78.8 parts by mass of water), dried, and then a connecting reinforcing layer sheet of rubber composition R3 was laminated on both the front and back surfaces to obtain a treated reed (thickness of about 0.7 mm) was used.

[0272] [Example 1] (Preparation of an uncrosslinked rubber belt (with a two-layer structure of stretchable rubber)) Two reinforcing fabric layer precursors (first reinforcing fabric layer precursor and second reinforcing fabric layer precursor), a compressed rubber layer sheet R1 (thickness 3.0 mm), a hard rubber layer sheet R5 (thickness 1.5 mm), and a second adhesive rubber layer sheet R2 (thickness 0.5 mm) were laminated in this order on the outer surface of a cylindrical drum. Then, a core wire was spirally wound around the outer surface. Furthermore, a first adhesive rubber layer sheet R2 (thickness 0.5 mm), a second stretchable rubber layer sheet R5 (thickness 1.5 mm), and a first stretchable rubber layer sheet R4 (thickness 1.3 mm) were laminated in this order on the outer surface around which the core wire was wound, forming a cylindrical uncrosslinked sleeve in which the uncrosslinked rubber layer and the core wire were laminated. That is, the outermost surface of the uncrosslinked sleeve was exposed to the rubber composition R4. The uncrosslinked rubber sheet containing short fibers was wound so that the orientation direction of the short fibers contained in the sheet was in the direction of the belt width. The obtained uncrosslinked sleeve was cut circumferentially while positioned on the outer circumference of a cylindrical drum to form an annular uncrosslinked rubber belt.

[0273] (Skibing process and outer covering process (covering process)) The uncrosslinked rubber belt was removed from the drum, and both sides of the uncrosslinked rubber belt were cut (skived) at a predetermined angle to form a V-shaped cross-section (skiving process). The V-shaped uncrosslinked rubber belt (belt body precursor: an uncrosslinked V-belt including a stretchable rubber layer, a core layer, a hard rubber layer, and a compression rubber layer) was then covered with two outer covering precursors (a first outer covering precursor and a second outer covering precursor) to form an uncrosslinked wrapped V-belt (coating process).

[0274] In the coating process, two outer covering precursors were used, and the width direction of the outer covering precursors was directed towards the circumferential direction in a cross-section perpendicular to the belt length direction (i.e., the length direction of the outer covering precursors was directed towards the belt length direction) and wrapped around the uncrosslinked rubber belt from the inner circumferential side, thereby coating the inner circumferential surface and both sides of the uncrosslinked wrapped V-belt section with the outer covering precursors (the outer circumferential surface was left exposed).

[0275] Furthermore, the outer fabric precursor was positioned so that the warp and weft threads were inclined at a 60° angle to the length of the belt.

[0276] (Connection process) The six obtained uncrosslinked wrapped V-belt sections were fitted into the annular grooves formed in the lower crosslinking mold, and then the treated bamboo blind (a precursor for the connecting reinforcement layer on the inner circumference of the belt) and the treated canvas (a precursor for the protective layer on the outer circumference of the belt) were set as tie band precursors on their radially outer portions. In other words, when setting the tie band precursors, the treated bamboo blind and then the treated canvas were wrapped around the six uncrosslinked wrapped V-belt sections, which were arranged in the width direction, along the circumferential direction (belt length direction), and the tie band precursors were set for the six uncrosslinked wrapped V-belt sections. The treated bamboo blind was positioned so that the longitudinal direction of the warp threads was approximately parallel to the belt width direction, and the longitudinal direction of the weft threads was approximately parallel to the belt circumference direction. The treated canvas was positioned so that the warp and weft threads were inclined at 60° with respect to the belt length direction.

[0277] The tie band precursor and the six uncrosslinked wrapped V-belt sections 1, set in this manner, were sandwiched between an upper crosslinking mold and a lower crosslinking mold, pressurized to 1.2 MPa, and heated at a crosslinking temperature of 160°C for 20 minutes to crosslink, thereby obtaining a crosslinked belt in which the six wrapped V-belt sections 1 (ASABE standard HB type, belt length 1600 mm) were connected and joined by tie bands.

[0278] The resulting cross-linked belt 1 was cut to produce a wrapped V-belt (cross-sectional dimensions: width 54.6 mm x thickness 12.7 mm) having three wrapped V-belt sections.

[0279] [Example 2] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the first stretchable rubber layer sheet of R5 (thickness 1.3 mm) was used instead of the first stretchable rubber layer sheet of R4 (thickness 1.3 mm).

[0280] [Example 3] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the R4 sheet for the second stretchable rubber layer (thickness 1.5 mm) was used instead of the R5 sheet for the second stretchable rubber layer (thickness 1.5 mm).

[0281] [Examples 4-7] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the first stretchable rubber layer sheets R6 to R9 (thickness 1.3 mm) shown in Tables 3 and 4 were used instead of the first stretchable rubber layer sheet R4 (thickness 1.3 mm).

[0282] [Example 8] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the thickness of the sheet for the first stretchable rubber layer R4 was changed to 1.8 mm and the thickness of the sheet for the second stretchable rubber layer R5 was changed to 1.0 mm.

[0283] [Example 9] In the preparation of the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that two reinforcing fabric layer precursors were not used.

[0284] [Example 10] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the R1 compression rubber layer sheet (1.5 mm thick) was used instead of the R5 hard rubber layer sheet (1.5 mm thick).

[0285] [Example 11] In the preparation of the bonded V-belt (bonding process), a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that a protective layer sheet of R4 (thickness 0.5 mm) was used instead of the treated canvas which is the precursor of the protective layer.

[0286] [Example 12] In the preparation of the bonded V-belt (joining process), a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that treated canvas was used instead of treated bamboo blinds to create a two-layer structure of treated canvas for the tie band precursor.

[0287] [Comparative Example 1] In the preparation of the uncrosslinked rubber belt, the first stretchable rubber layer sheet (R4, thickness 1.3 mm) was not used, the thickness of the second stretchable rubber layer sheet (R5, thickness 1.8 mm) was changed, and in the skiving process and the outer covering process (covering process), the entire surface of the uncrosslinked wrapped V-belt portion was covered twice with the outer covering precursor (covering the outer periphery as well), except that the process was the same as in Example 1 to produce the wrapped bonded V-belt.

[0288] [Comparative Examples 2-4] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the first stretchable rubber layer sheets R10 to R12 (thickness 1.3 mm) shown in Table 5 were used instead of the first stretchable rubber layer sheet R4 (thickness 1.3 mm).

[0289] [Peel test] The obtained wrapped V-belt was cut along the three wrapped V-belt sections (divided into three pieces), and the peel force of the tie band was measured at temperature conditions of 23°C or 150°C. Specifically, a 15 cm section was cut from the separated endless belt in the belt length direction to be used as a sample for the peel test. An incision was made with a cutting tool between the tie band and the wrapped V-belt section at the cut surface, and then the tie band and the wrapped V-belt section were pulled apart using an Autograph (Shimadzu Corporation "AGS-J10kN") in the direction of separation (peeling angle of 180°, i.e., folding the tie band 180° relative to the wrapped V-belt section), and the peel force was measured when the belt was peeled along the belt length direction. The peel force was obtained as a value per 1 cm width by dividing the measured tensile force by the width of the peeled surface (width of the outer surface of the wrapped V-belt section).

[0290] For the peel test, samples were cut from three arbitrary locations on the separated endless belt, and the arithmetic mean of the values ​​(peeling force) obtained from the three samples was adopted.

[0291] [Durability Test] As shown in Figure 5, the durability life of a wrapped V-belt was evaluated using a three-axis running test machine equipped with a 177 mm diameter drive (Dr.) pulley, a 177 mm diameter driven (Dn.) pulley, and an 80 mm diameter rear tension (Ten.) pulley. Specifically, a wrapped V-belt was mounted on each pulley, and a downward axial load of 170 N was applied to the rear tension pulley as shown in the figure. The contact angle of the belt with respect to the rear tension pulley (the central angle with respect to the arc in which the belt and pulley are in contact) was adjusted to 20 degrees. Rice grains were fed into the area near the inlet of the drive pulley (position A in the figure) at a rate of 3 grains per second, while the machine alternated between running for 5 minutes at a rotation speed of 550 rpm on the drive pulley and stopping for 1 minute. The load on the driven pulley was set to 7.7 kW, and the belt was run for a maximum of 200 hours at an ambient temperature of 70°C. If the tie band completely detached, the test was terminated at that point. If the vehicle was driven for the maximum 200 hours, the length of the tie band detachment in the belt width direction (maximum length) was checked.

[0292] Tables 3 to 5 show the evaluation results of the wrapped bonded V-belts obtained in Examples 1 to 12 and Comparative Examples 1 to 4.

[0293] [Table 3]

[0294] [Table 4]

[0295] [Table 5]

[0296] The following facts can be gleaned from the results in Tables 3-5.

[0297] In Example 1, no delamination of the tie band occurred during the endurance driving test.

[0298] In Example 2, the resulting stretchable rubber layer has a single-layer structure, and the hardness of the stretchable rubber layer is higher than that of the first stretchable rubber layer (outer periphery) in Example 1. However, no delamination of the tie band occurred during the durability driving test.

[0299] In Example 3, the resulting stretchable rubber layer has a single-layer structure, and the hardness of the stretchable rubber layer is lower than that of the second stretchable rubber layer (inner circumference) in Example 1. However, no delamination of the tie band occurred during the durability driving test.

[0300] Example 4 is an example in which the first stretchable rubber layer (outer periphery) contains hard carbon black, but the tie band partially peeled off, possibly due to increased internal heat generation.

[0301] Example 5 is an example where the amount of softening agent in the first stretchable rubber layer (outer periphery) is small. However, the tie band partially peeled off, possibly because the difference in hardness between the rubber of the connecting reinforcement layer sheet laminated on the bamboo blind and the rubber of the first stretchable rubber layer (outer periphery) became large, causing stress to concentrate at the interface.

[0302] Example 6 is an example where the first stretchable rubber layer (outer periphery) contains a large amount of softening agent, but perhaps due to the large amount of softening agent, the tie band partially peeled off.

[0303] Example 7 is an example in which the first stretchable rubber layer (outer periphery) does not contain sulfur. However, perhaps because the crosslinking density decreased due to the absence of sulfur, the tie band partially peeled off.

[0304] Example 8 is an example in which the thickness of the first stretchable rubber layer (outer circumference) was increased and the thickness of the second stretchable rubber layer (inner circumference) was decreased, but the tie band partially peeled off, possibly because the lateral pressure resistance decreased.

[0305] Example 9 is an example where a reinforcing fabric layer was not provided, but the tie band partially peeled off, possibly because the flexibility decreased and heat generation increased.

[0306] Example 10 is an example in which a hard rubber layer was not provided (an example in which a single layer of compressed rubber was obtained), but the tie band partially peeled off, possibly because the lateral pressure resistance was reduced.

[0307] Example 11 is an example in which a rubber composition was used as the protective layer for the tie band instead of treated canvas. Similar to Example 1, no peeling of the tie band occurred during the durability running test.

[0308] Example 12 is an example in which treated canvas was used instead of treated bamboo blinds as the connecting reinforcement layer for the tie band, but the tie band partially peeled off, possibly because the treated canvas had a low rubber content.

[0309] Comparative Example 1 is an example in which the entire perimeter of the wrapped V-belt is covered with an outer sheath, and the stretchable rubber layer and the tie band are not in contact. However, the tie band completely peeled off during the durability driving test.

[0310] Comparative Example 2 is an example where the first stretchable rubber layer (outer periphery) has many short fibers, but the tie band completely peeled off.

[0311] Comparative Example 3 is an example where the amount of carbon black in the first stretchable rubber layer (outer periphery) is small, but the tie band completely peeled off, possibly due to a decrease in lateral pressure resistance.

[0312] Comparative Example 4 is an example where the first stretchable rubber layer (outer periphery) contains a large amount of carbon black, but the tie band completely peeled off.

[0313] <Examples 13-17 (Modification of short fibers)> [Rubber composition] (Materials used) The rubber composition is identical to that of Examples 1-12 and Comparative Examples 1-4.

[0314] (Preparation of uncrosslinked rolled rubber sheets and bulk uncrosslinked rubber compositions for friction) Sheets for compression rubber layers or hard rubber layers, bulk uncrosslinked (unvulcanized) rubber compositions for friction, sheets for connecting reinforcement layers, and sheets for protective layers were prepared in the same manner as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0315] Rubber compositions R13 to R17, as shown in Table 6, were mixed in a Banbury mixer. These mixed rubbers were then passed through a calender roll to produce uncrosslinked (unvulcanized) rolled rubber sheets of a predetermined thickness, which were used as sheets for stretched rubber layers.

[0316] Furthermore, the short fibers contained in the uncrosslinked rubber sheet were oriented in the rolling direction.

[0317] [Table 6]

[0318] [Rubber hardness of cross-linked rubber] The rubber hardness (Type A) of rubber compositions having the compositions shown in Table 6 was measured using the same method as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0319] [Core wire (processing code)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0320] [Outer covering precursor, reinforcing fabric layer precursor, or protective layer precursor (treated canvas)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0321] [Connecting reinforcement layer precursor (treated bamboo blind)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0322] [Examples 13-17] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the first stretchable rubber layer sheet (thickness 1.3 mm) of R4 and the second stretchable rubber layer sheet (thickness 1.5 mm) of R5 were replaced with the first stretchable rubber layer sheets (thickness 1.3 mm) of R13 to R17 and the second stretchable rubber layer sheets (thickness 1.5 mm), respectively.

[0323] [Peel test] The peeling force of the wrapped bonded V-belts obtained in Examples 13-17 was measured using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0324] [Durability Test] For the wrapped bonded V-belts obtained in Examples 13 to 17, the durability running time and delamination length were measured using the same method as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0325] Table 7 shows the evaluation results of the wrapped bonded V-belts obtained in Examples 13-17.

[0326] [Table 7]

[0327] Example 13 is an example in which the first stretchable rubber layer (outer periphery) does not contain short fibers, but the tie band partially peeled off, possibly due to a decrease in lateral pressure resistance.

[0328] Examples 14-17 show an increase in the amount of short fibers compared to Example 3, but the tie band partially peeled off, possibly due to decreased adhesion. A comparison between Example 15 and Example 16 showed that combining cotton short fibers with nylon short fibers yielded better results than combining cotton short fibers with aramid short fibers. Furthermore, a comparison between Example 15 and Example 17 showed that a higher proportion of cotton short fibers than nylon short fibers yielded better results.

[0329] <Examples 18-25 (Change of Filler)> [Rubber composition] (Materials used) The materials that differ from the rubber compositions of Examples 1-12 and Comparative Examples 1-4 are as follows: Carbon Black SRF: "Seas S" manufactured by Tokai Carbon Co., Ltd., DBP absorption rate 68 mL / 100 g, BET specific surface area 27 m² 2 / g, iodine adsorption capacity 26g / kg, average primary particle diameter 66nm Calcium carbonate: "Super 1500" manufactured by Maruo Calcium Co., Ltd.

[0330] (Preparation of uncrosslinked rolled rubber sheets and bulk uncrosslinked rubber compositions for friction) Sheets for compression rubber layers or hard rubber layers, bulk uncrosslinked (unvulcanized) rubber compositions for friction, sheets for connecting reinforcement layers, and sheets for protective layers were prepared in the same manner as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0331] The rubber compositions R18 to R25, as shown in Table 8, were mixed in a Banbury mixer. These mixed rubbers were then passed through a calender roll to produce uncrosslinked (unvulcanized) rolled rubber sheets of a predetermined thickness, which were used as sheets for stretched rubber layers.

[0332] Furthermore, the short fibers contained in the uncrosslinked rubber sheet were oriented in the rolling direction.

[0333] [Table 8]

[0334] [Rubber hardness of cross-linked rubber] The rubber hardness (Type A) of rubber compositions having the compositions shown in Table 8 was measured using the same method as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0335] [Core wire (processing code)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0336] [Outer covering precursor, reinforcing fabric layer precursor, or protective layer precursor (treated canvas)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0337] [Connecting reinforcement layer precursor (treated bamboo blind)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0338] [Examples 18-25] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the first stretchable rubber layer sheet (thickness 1.3 mm) of R4 and the second stretchable rubber layer sheet (thickness 1.5 mm) of R5 were replaced with the first stretchable rubber layer sheets (thickness 1.3 mm) of R18 to R25 and the second stretchable rubber layer sheets (thickness 1.5 mm), respectively.

[0339] [Peel test] The peeling force of the wrapped bonded V-belts obtained in Examples 18-25 was measured using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0340] [Durability Test] For the wrapped bonded V-belts obtained in Examples 18-25, the durability running time and delamination length were measured using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0341] The evaluation results of the wrapped bonded V-belts obtained in Examples 18-25 are shown in Tables 9-10.

[0342] [Table 9]

[0343] [Table 10]

[0344] Example 18 is an example in which the amount of carbon black was reduced compared to Example 3, but the tie band partially peeled off, possibly due to a decrease in lateral pressure resistance.

[0345] Example 19 is an example in which the amount of carbon black was increased compared to Example 3. However, the tie band partially peeled off, possibly because the difference in hardness between the rubber of the connecting reinforcement layer sheet laminated on the bamboo blind and the rubber of the first stretched rubber layer (outer periphery) became large, causing stress to concentrate at the interface.

[0346] Example 20 is an example in which carbon black was replaced with SRF compared to Example 3, but the tie band partially peeled off, possibly due to a decrease in lateral pressure resistance.

[0347] Example 21 is an example in which carbon black was replaced with HAF compared to Example 3. However, the tie band partially peeled off, possibly because the difference in hardness between the rubber of the connecting reinforcement layer sheet laminated on the bamboo blind and the rubber of the first stretched rubber layer (outer periphery) became large, causing stress to concentrate at the interface.

[0348] Example 22 is an example in which calcium carbonate was added to Example 20, but there was no significant difference in the results.

[0349] Example 23 is an example in which the amount of SRF was increased compared to Example 22, but there was no significant difference in the results.

[0350] Example 24 is an example in which the amount of calcium carbonate was increased compared to Example 22, but no peeling of the tie band occurred.

[0351] Example 25 is an example in which the amount of calcium carbonate was increased compared to Example 24, but the tie band partially peeled off, possibly due to a decrease in lateral pressure resistance.

[0352] <Examples 26-30 (Modification of Crosslinking System)> [Rubber composition] (Materials used) The materials that differ from the rubber compositions of Examples 1-12 and Comparative Examples 1-4 are as follows: Co-crosslinking agent MPBM (N,N'-m-phenylenedimaleimide): "Balnock PM" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0353] (Preparation of uncrosslinked rolled rubber sheets and bulk uncrosslinked rubber compositions for friction) Sheets for compression rubber layers or hard rubber layers, bulk uncrosslinked (unvulcanized) rubber compositions for friction, sheets for connecting reinforcement layers, and sheets for protective layers were prepared in the same manner as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0354] Rubber compositions R26 to R30, as shown in Table 11, were mixed in a Banbury mixer. These mixed rubbers were then passed through a calender roll to produce uncrosslinked (unvulcanized) rolled rubber sheets of a predetermined thickness, which were used as sheets for stretched rubber layers.

[0355] Furthermore, the short fibers contained in the uncrosslinked rubber sheet were oriented in the rolling direction.

[0356] [Table 11]

[0357] [Rubber hardness of cross-linked rubber] The rubber hardness (Type A) of rubber compositions having the compositions shown in Table 11 was measured using the same method as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0358] [Core wire (processing code)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0359] [Outer covering precursor, reinforcing fabric layer precursor, or protective layer precursor (treated canvas)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0360] [Connecting reinforcement layer precursor (treated bamboo blind)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0361] [Examples 26-30] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 1, except that the first stretchable rubber layer sheet (thickness 1.3 mm) of R4 and the second stretchable rubber layer sheet (thickness 1.5 mm) of R5 were replaced with the first stretchable rubber layer sheets (thickness 1.3 mm) of R26 to R30 and the second stretchable rubber layer sheets (thickness 1.5 mm), respectively.

[0362] [Peel test] The peeling force of the wrapped bonded V-belts obtained in Examples 26-30 was measured using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0363] [Durability Test] For the wrapped bonded V-belts obtained in Examples 26-30, the durability running time and delamination length were measured using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0364] Table 12 shows the evaluation results of the wrapped bonded V-belts obtained in Examples 26-30.

[0365] [Table 12]

[0366] Example 26 is an example in which the amount of sulfur and crosslinking accelerator was reduced compared to Example 3, but the tie band partially peeled off, possibly due to a decrease in lateral pressure resistance.

[0367] Example 27 is an example in which the amount of sulfur was increased compared to Example 3, but no peeling of the tie band occurred.

[0368] Example 28 is an example in which the amount of sulfur was increased compared to Example 27, but the tie band partially peeled off, possibly because the difference in hardness between the rubber of the connecting reinforcement layer sheet laminated on the bamboo blind and the rubber of the first stretched rubber layer (outer periphery) became large, causing stress to concentrate at the interface.

[0369] Example 29 is an example in which a co-crosslinking agent was added to Example 3, but no peeling of the tie band occurred.

[0370] Example 30 is an example in which the amount of co-crosslinking agent was increased compared to Example 29. However, the tie band partially peeled off, possibly because the difference in hardness between the rubber of the connecting reinforcement layer sheet laminated on the bamboo blind and the rubber of the first stretched rubber layer (outer periphery) became large, causing stress to concentrate at the interface.

[0371] <Examples 31-32 (Multiple Condition Changes)> [Rubber composition] (Materials used) The rubber composition is identical to that of Examples 1-30 and Comparative Examples 1-4.

[0372] (Preparation of uncrosslinked rolled rubber sheets and bulk uncrosslinked rubber compositions for friction) Sheets for compression rubber layers or hard rubber layers, bulk uncrosslinked (unvulcanized) rubber compositions for friction, sheets for connecting reinforcement layers, and sheets for protective layers were prepared in the same manner as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0373] Rubber compositions R31 and R32, as shown in Table 13, were mixed in a Banbury mixer. These mixed rubbers were then passed through a calender roll to produce uncrosslinked (unvulcanized) rolled rubber sheets of a predetermined thickness, which were used as sheets for stretched rubber layers.

[0374] Furthermore, the short fibers contained in the uncrosslinked rubber sheet were oriented in the rolling direction.

[0375] [Table 13]

[0376] [Rubber hardness of cross-linked rubber] The rubber hardness (Type A) of rubber compositions having the compositions shown in Table 13 was measured using the same method as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0377] [Core wire (processing code)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0378] [Outer covering precursor, reinforcing fabric layer precursor, or protective layer precursor (treated canvas)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0379] [Connecting reinforcement layer precursor (treated bamboo blind)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0380] [Examples 31 and 32] In preparing the uncrosslinked rubber belt, a wrapped V-belt was manufactured in the same manner as in Example 1, except that the first stretchable rubber layer sheet R31 and R32 (thickness 1.3 mm) and the second stretchable rubber layer sheet R31-R32 (thickness 1.5 mm) were used instead of the first stretchable rubber layer sheet R4 (thickness 1.3 mm) and the second stretchable rubber layer sheet R5 (thickness 1.5 mm), respectively.

[0381] [Peel test] The peeling force of the wrapped bonded V-belts obtained in Examples 31 and 32 was measured in the same manner as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0382] [Durability Test] The wrapped bonded V-belts obtained in Examples 31 and 32 were measured for their durability running time and delamination length in the same manner as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0383] Table 14 shows the evaluation results of the wrapped bonded V-belts obtained in Examples 31 and 32.

[0384] [Table 14]

[0385] In Examples 31 and 32, no delamination of the tie band occurred during the endurance driving test.

[0386] <Examples 33-38 (Change of rubber type)> [Rubber composition] (Materials used) The materials that differ from the rubber compositions of Examples 1-12 and Comparative Examples 1-4 are as follows: EPDM: Dow Chemical's "Nordel 6530XFC," ethylene content 55% by mass, diene (ENB) content 8.5% by mass EBDM: Mitsui Chemicals, Inc. "K-9330M", ethylene content 50% by mass, diene (ENB) content 7.1% by mass Anti-aging agent DCD (4,4'-bis(α,α-dimethylbenzyl)diphenylamine): "Nocrack CD" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Anti-aging agent MBI (2-mercaptobenzimidazole): "Nocrack MB" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Softener B: "Diana Process Oil PW90" manufactured by Idemitsu Kosan Co., Ltd. Peroxide crosslinking agent: 1,3-bis(2-t-butylperoxyisopropyl)benzene

[0387] (Preparation of uncrosslinked rolled rubber sheets and bulk uncrosslinked rubber compositions for friction) The rubber composition E1 shown in Table 15 was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce an uncrosslinked (unvulcanized) rolled rubber sheet of a predetermined thickness, which was used as a sheet for the compression rubber layer.

[0388] The rubber composition E2 shown in Table 15 was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce an uncrosslinked (unvulcanized) rolled rubber sheet of a predetermined thickness, which was used as the sheet for the adhesive rubber layer (inner and outer circumference of the core wire).

[0389] The rubber composition E3 shown in Table 15 was mixed in a Banbury mixer to prepare a bulk, uncrosslinked (unvulcanized) rubber composition for friction to form an outer covering precursor or reinforcing fabric layer precursor.

[0390] The rubber composition E3 shown in Table 15 was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce an uncrosslinked (unvulcanized) rolled rubber sheet of a predetermined thickness, which was used as a sheet for the connecting reinforcement layer.

[0391] Rubber composition E4, as shown in Table 16, was mixed in a Banbury mixer, and this mixed rubber was passed through a calender roll to produce uncrosslinked (unvulcanized) rolled rubber sheets of a predetermined thickness, which were used as sheets for hard rubber layers or sheets for stretchable rubber layers.

[0392] Rubber compositions E5 to E9, as shown in Table 16, were mixed in a Banbury mixer. These mixed rubbers were then passed through a calender roll to produce uncrosslinked (unvulcanized) rolled rubber sheets of a predetermined thickness, which were used as sheets for stretched rubber layers.

[0393] Furthermore, the short fibers contained in the uncrosslinked rubber sheet were oriented in the rolling direction.

[0394] [Table 15]

[0395] [Table 16]

[0396] [Rubber hardness of cross-linked rubber] The rubber hardness (Type A) of rubber compositions having the compositions shown in Tables 15 and 16 was measured using the same method as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0397] [Core wire (processing code)] The samples were prepared using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0398] [Outer covering precursor, reinforcing fabric layer precursor, or protective layer precursor (treated canvas)] The samples were prepared in the same manner as in Examples 1-12 and Comparative Examples 1-4, except that rubber composition E3 was used instead of rubber composition R3.

[0399] [Connecting reinforcement layer precursor (treated bamboo blind)] The samples were prepared in the same manner as in Examples 1-12 and Comparative Examples 1-4, except that rubber composition E3 was used instead of rubber composition R3.

[0400] [Example 33] (Preparation of uncrosslinked rubber belts) On the outer surface of a cylindrical drum, two reinforcing fabric layer precursors (first reinforcing fabric layer precursor and second reinforcing fabric layer precursor), an E1 compression rubber layer sheet (3.0 mm thick), an E4 hard rubber layer sheet (1.5 mm thick), and an E2 second adhesive rubber layer sheet (0.5 mm thick) were laminated in this order. Then, a core wire was spirally wound around the outer surface. Furthermore, on the outer surface around which the core wire was wound, an E2 first adhesive rubber layer sheet (0.5 mm thick), an E4 second stretch rubber layer sheet (1.5 mm thick), and an E4 first stretch rubber layer sheet (1.3 mm thick) were laminated in this order to form a cylindrical uncrosslinked sleeve in which the uncrosslinked rubber layer and the core wire were laminated. That is, the outermost surface of the uncrosslinked sleeve was exposed rubber composition E4. The uncrosslinked rubber sheet containing short fibers was wound so that the orientation direction of the short fibers contained in the sheet was in the direction of the belt width. The obtained uncrosslinked sleeve was cut circumferentially while positioned on the outer circumference of a cylindrical drum to form an annular uncrosslinked rubber belt.

[0401] (Skibing process, coating process, and coupling process) Using the obtained uncrosslinked rubber belt, a wrapped bonded V-belt (cross-sectional dimensions: width 54.6 mm x thickness 12.7 mm) having three wrapped V-belt sections was manufactured in the same manner as in Example 1, through a skiving process, an outer covering process (covering process), and a bonding process (bonded V-belt preparation process).

[0402] [Examples 34-38] In preparing the uncrosslinked rubber belt, a wrapped bonded V-belt was manufactured in the same manner as in Example 33, except that the sheets for the first stretchable rubber layer (1.3 mm thick) of E4 and the sheets for the second stretchable rubber layer (1.5 mm thick) of E5 to E9 were used instead, respectively.

[0403] [Peel test] The peeling force of the wrapped bonded V-belts obtained in Examples 33-38 was measured using the same method as in Examples 1-12 and Comparative Examples 1-4.

[0404] [Durability Test] For the wrapped bonded V-belts obtained in Examples 33 to 38, the durability running time and delamination length were measured using the same method as in Examples 1 to 12 and Comparative Examples 1 to 4.

[0405] Table 17 shows the evaluation results of the wrapped bonded V-belts obtained in Examples 33-38.

[0406] [Table 17]

[0407] In Examples 33-35, no delamination of the tie bands occurred during the endurance driving test.

[0408] Example 36 is an example in which the amount of carbon black was reduced compared to Example 33, but the tie band partially peeled off, possibly due to a decrease in lateral pressure resistance.

[0409] Example 37 is an example in which the amount of silica was reduced and the amount of carbon black was increased compared to Example 33, but the tie band partially peeled off, possibly due to a decrease in adhesion.

[0410] Example 38 is an example in which a softening agent was added to Example 33, but the tie band partially peeled off, possibly due to a decrease in adhesiveness. [Industrial applicability]

[0411] The wrapped V-belt of the present invention can be used in general industrial machinery such as compressors, generators, and pumps, as well as agricultural machinery such as combine harvesters, rice transplanters, and lawnmowers. It can also be used in high-load machinery used in long-span layouts under high loads, such as large agricultural machinery used in Europe and the United States, specifically tillers, vegetable transplanters, transplanters, binders, combine harvesters, vegetable harvesters, threshing machines, bean cutters, corn harvesters, potato harvesters, and beet harvesters. [Explanation of Symbols]

[0412] 1... Wrapped V-belt V... Wrapped V-belt section 2a…protective layer 2b…Connecting reinforcement layer T... Thai band 3…Stretchable rubber layer 3a...First stretchable rubber layer 3b…Second stretch rubber layer 4...Core layer 4a…core wire 4b...Adhesive rubber layer 5…Hard rubber layer 6…Compressed rubber layer 7…Reinforcement fabric layer 7a...First reinforcing fabric layer 7b…Second reinforcing fabric layer 8…Outer covering cloth 8a...First outer covering 8b…Second outer covering fabric

Claims

1. A wrapped V-belt comprising a belt body covered with an outer sheath, a plurality of wrapped V-belt sections, and tie bands connecting the plurality of wrapped V-belt sections on the outer circumferential surface of each wrapped V-belt section, The belt body includes a core layer containing a core body, at least one stretchable rubber layer laminated on the outer circumference side of the core layer, and a compression rubber layer laminated on the inner circumference side of the core layer. The outer surface of the wrapped V-belt portion is not covered by the outer covering, and the stretchable rubber layer is exposed. The exposed stretchable rubber layer is formed of a crosslinked rubber composition containing rubber components and carbon black. The carbon black includes soft carbon black, and A wrapped bonded V-belt in which the proportion of carbon black is 20 to 80 parts by mass per 100 parts by mass of the rubber component.

2. The wrapped bonded V-belt according to claim 1, wherein the crosslinked rubber composition further comprises a softening agent, and the proportion of the softening agent is 2 to 10 parts by mass per 100 parts by mass of the rubber component.

3. The wrapped bonded V-belt according to claim 1 or 2, wherein the crosslinked rubber composition contains sulfur as a crosslinking agent.

4. The wrapped bonded V-belt according to claim 1 or 2, wherein the crosslinked rubber composition further comprises short fibers, and the proportion of the short fibers is 5 to 50 parts by mass per 100 parts by mass of the rubber component.

5. The wrapped bonded V-belt according to claim 1 or 2, wherein the stretchable rubber layer has a two-layer structure including a first stretchable rubber layer on the outer circumference and a second stretchable rubber layer on the inner circumference, and the rubber hardness of the second stretchable rubber layer is greater than the rubber hardness of the first stretchable rubber layer.

6. The wrapped bonded V-belt according to claim 5, wherein the average thickness of the second stretchable rubber layer is greater than the average thickness of the first stretchable rubber layer.

7. The wrapped bonded V-belt according to claim 1 or 2, wherein a reinforcing fabric layer is interposed between the compression rubber layer and the outer covering fabric.

8. The wrapped bonded V-belt according to claim 1 or 2, wherein a hard rubber layer is interposed between the core layer and the compression rubber layer.

9. The wrapped bonded V-belt according to claim 1 or 2, wherein the tie band includes a bamboo blind fabric.

10. A coating step in which the belt body precursor is covered with an outer covering precursor to form a wrapped V-belt precursor, A method for manufacturing a wrapped V-belt, comprising at least a connecting step of connecting the outer surfaces of a plurality of wrapped V-belt precursors obtained in the coating step with tie band precursors, A method for manufacturing a wrapped bonded V-belt according to claim 1 or 2, wherein in the coating step, only the inner circumferential surface and both sides of the belt body precursor are coated.

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