Power transmission belt

Abstract

To provide a high-performance transmission belt.SOLUTION: A transmission belt B has at least a portion 111 of a belt body 11 formed of a crosslinked rubber composition. The crosslinked rubber composition is composed of a crosslinked product of an uncrosslinked rubber composition containing a rubber component, nanofibers, carbon black, zinc dimethacrylate, and an amylphenol disulfide polymer. In the crosslinked rubber composition, the nanofibers are oriented in the belt width direction. In the uncrosslinked rubber composition, the content of the carbon black is between 25 parts by mass and 70 parts by mass, and the sum of the contents of the carbon black and the zinc dimethacrylate is between 35 parts by mass and 75 parts by mass, relative to 100 parts by mass of the rubber component.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a power transmission belt. [Background technology]

[0002] It is known to use nanofibers with a fiber diameter of 1 μm or less as a reinforcing material. For example, Patent Document 1 discloses that the compression rubber layer constituting the V-side of a V-belt is formed from a crosslinked rubber composition containing a rubber component, nanofibers of polyethylene terephthalate fibers, and short para-aramid fibers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6145170 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a high performance power transmission belt. [Means for solving the problem]

[0005] The present invention provides a power transmission belt having at least a portion of a belt body formed from a crosslinked rubber composition, the crosslinked rubber composition being composed of a crosslinked product of an uncrosslinked rubber composition containing a rubber component, nanofibers, carbon black, zinc dimethacrylate, and an amylphenol disulfide polymer, the nanofibers being oriented in the belt width direction in the crosslinked rubber composition, and the uncrosslinked rubber composition having a carbon black content of 25 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the rubber component, and a sum of the carbon black and zinc dimethacrylate contents of 35 parts by mass or more and 75 parts by mass or less. [Effects of the Invention]

[0006] According to the present invention, the cross-linked rubber composition forming at least a part of the belt body is composed of a cross-linked product of an uncross-linked rubber composition containing a rubber component, nanofibers, carbon black, and zinc dimethacrylate, and in the cross-linked rubber composition, the nanofibers are oriented in the belt width direction, and in the uncross-linked rubber composition, the carbon black content is 25 parts by mass or more and 70 parts by mass or less, and the sum of the carbon black and zinc dimethacrylate contents is 35 parts by mass or more and 75 parts by mass or less, per 100 parts by mass of the rubber component, thereby achieving high performance. [Brief explanation of the drawings]

[0007] [Figure 1A] 1 is a perspective view of a section of a double-cogged V-belt according to an embodiment. FIG. [Figure 1B] 1 is a vertical cross-sectional view of a portion of a double-cogged V-belt according to an embodiment. [Figure 1C] 1 is a cross-sectional view of a double-cogged V-belt according to an embodiment. [Figure 2] FIG. 1 is a perspective view of a composite material. [Figure 3A] 1 is a cross-sectional view showing the configuration of a transmission using a double-cogged V-belt according to an embodiment. [Figure 3B] 1 is a vertical cross-sectional view showing the configuration of a transmission using a double-cogged V-belt according to an embodiment. [Figure 4A] FIG. 3 is a first explanatory view of a forming and cross-linking step in the method for manufacturing a double-cogged V-belt according to the embodiment. [Figure 4B] FIG. 4 is a second explanatory view of the forming and cross-linking step in the manufacturing method of the double-cogged V-belt according to the embodiment. [Figure 4C] FIG. 6 is a third explanatory view of the forming and cross-linking step in the method for manufacturing the double-cogged V-belt according to the embodiment. [Figure 4D] FIG. 10 is a fourth explanatory view of the forming and cross-linking step in the method for manufacturing the double-cogged V-belt according to the embodiment. [Figure 4E] FIG. 5 is a fifth explanatory view of the forming and cross-linking step in the method for manufacturing the double-cogged V-belt according to the embodiment. [Figure 4F] FIG. 6 is a sixth explanatory diagram of the forming and cross-linking step in the method for manufacturing the double-cogged V-belt according to the embodiment. [Figure 4G] FIG. 7 is a seventh explanatory view of the forming and cross-linking step in the manufacturing method of the double-cogged V-belt according to the embodiment. [Figure 4H] FIG. 10 is an eighth explanatory view of the forming and cross-linking step in the manufacturing method of the double-cogged V-belt according to the embodiment. [Figure 5A] FIG. 4 is a first explanatory view of a width-cutting and V-side forming step in the manufacturing method of the double-cogged V-belt according to the embodiment. [Figure 5B] FIG. 10 is a second explanatory view of the width-cutting and V-side forming step in the manufacturing method of the double-cogged V-belt according to the embodiment. [Figure 6A] FIG. 1 is a diagram showing the low-speed layout of a belt running tester. [Figure 6B] FIG. 1 is a diagram showing a high-speed layout of a belt running tester. DETAILED DESCRIPTION OF THE INVENTION

[0008] The embodiments will be described in detail below.

[0009] 1A to 1C show a double cog V-belt B (power transmission belt) according to an embodiment. The double cog V-belt B according to the embodiment is an endless power transmission member used in, for example, a transmission device of a motorcycle, an automobile, or other general-purpose machine.

[0010] The cross-sectional shape of the double-cogged V-belt B according to the embodiment is a trapezoid with the lower base shorter than the upper base at the inner circumferential portion and a rectangular shape with an elongated outer circumferential portion. The belt length of the double-cogged V-belt B according to the embodiment is, for example, 700 mm or more and 1000 mm or less. The belt width is, for example, 10 mm or more and 36 mm or less. The belt thickness is, for example, 13 mm or more and 16 mm or less.

[0011] The double-cogged V-belt B according to the embodiment has a lower cog C on the inner circumferential side. Lare arranged at a constant pitch along the length of the belt. L The outer periphery of the double cog V-belt B according to the embodiment has an upper cog C. U are arranged at a constant pitch along the length of the belt. U The vertical cross section of the outer periphery is formed in a trapezoidal shape.

[0012] The double-cogged V-belt B according to the embodiment includes a belt body 11 made of a rubber material, a reinforcing fabric 12 made of a fiber material, and a core wire 13. The belt body 11 has an inner compression rubber layer 111, an outer tension rubber layer 112, and an adhesive rubber layer 113 therebetween. The reinforcing fabric 12 covers the inner peripheral surface of the compression rubber layer 111 and supports the lower cog C. L The core wire 13 is embedded in the middle of the adhesive rubber layer 113 in the belt thickness direction, and is provided so as to form a spiral having a pitch in the belt width direction.

[0013] V-shaped side surfaces 111a, which become pulley contact surfaces, are formed on both sides of the compression rubber layer 111. The V-shaped angle in the cross section formed by the V-shaped side surfaces 111a is, for example, 27° or more and 33° or less.

[0014] The compression rubber layer 111, which is a portion that constitutes the V-side surface 111a, is formed of a crosslinked rubber composition X. The crosslinked rubber composition X is composed of a crosslinked product of an uncrosslinked rubber composition Y.

[0015] The uncrosslinked rubber composition Y contains a rubber component, nanofibers, carbon black as a reinforcing material, and zinc dimethacrylate as a co-crosslinking agent.

[0016] Examples of the rubber component include ethylene-α-olefin elastomer (EPDM, EPR), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber (H-NBR), etc. The rubber component preferably contains one or more of these, and from the viewpoint of obtaining excellent durability, it is more preferable to contain ethylene-α-olefin elastomer (EPDM, EPR) or chloroprene rubber (CR).

[0017] When the rubber component contains an ethylene-α-olefin elastomer, the ethylene content is preferably 45% by mass or more and 55% by mass or less, more preferably 50% by mass or more and 53% by mass or less, from the viewpoint of obtaining excellent durability. When the rubber component contains EPDM, the diene component is preferably ethylidene norbornene (ENB) from the viewpoint of obtaining excellent durability, and the diene content (ENB content) is preferably 6% by mass or more and 12% by mass or less, more preferably 7% by mass or more and 8% by mass or less, from the same viewpoint.

[0018] The nanofibers are fine fibers having a fiber diameter d1 of 1 μm or less (1000 nm or less). From the viewpoint of obtaining excellent durability, the fiber diameter d1 of the nanofibers is preferably 300 nm or more and 1000 nm or less, more preferably 500 nm or more and 900 nm or less. From the same viewpoint, the fiber length 11 of the nanofibers is preferably 0.3 mm or more and 5 mm or less, more preferably 0.5 mm or more and 1.5 mm or less. From the same viewpoint, the ratio of the fiber length 11 of the nanofibers to the fiber diameter d1 (l1 / d1: aspect ratio) is preferably 300 or more and 5000 or less, more preferably 1200 or more and 2000 or less, and even more preferably 1350 or more and 1500 or less.

[0019] Examples of nanofibers include synthetic nanofibers such as polyethylene terephthalate fibers (hereinafter referred to as "PET fibers") and polyamide fibers (6-nylon fibers, 6,6-nylon fibers); and naturally derived nanofibers such as cellulose nanofibers. The nanofiber preferably contains one or more of these nanofibers, and from the viewpoint of obtaining excellent durability, it is more preferable to contain PET nanofibers.

[0020] From the viewpoint of obtaining excellent durability, the content A of nanofibers in the uncrosslinked rubber composition Y is preferably 1 part by mass or more and 5 parts by mass or less, more preferably 2 parts by mass or more and 3 parts by mass or less, per 100 parts by mass of the rubber component.

[0021] In the uncrosslinked rubber composition Y, the nanofibers are preferably blended into the rubber component in the form of a composite material M having a sea-island structure of a sea of ​​thermoplastic resin R and numerous islands of bundles of nanofibers F, as shown in Fig. 2. In this case, the uncrosslinked rubber composition Y contains the nanofibers F dispersed in the rubber component because the thermoplastic resin R melts and diffuses into the rubber component during kneading.

[0022] This composite material M is obtained by cutting conjugate fibers, in which nanofibers F are present in the form of islands, independent of each other and arranged in parallel, in a sea polymer of thermoplastic resin R, into rod shapes. The outer diameter of the composite material M is, for example, 10 μm or more and 100 μm or less. The length of the composite material M is the same as the fiber length 11 of the nanofibers F, and is preferably 0.3 mm or more and 5 mm or less, more preferably 0.5 mm or more and 1.5 mm or less.

[0023] Examples of thermoplastic resins R include polyethylene resins, ethylene-vinyl acetate copolymer resins, nylon-based resins, and urethane-based resins. The thermoplastic resin R preferably contains one or more of these. Since the thermoplastic resin R diffuses into the rubber component during kneading, it is preferable that the thermoplastic resin R has high compatibility with the rubber component. Therefore, when the rubber component has low polarity, the thermoplastic resin R preferably contains low-polarity polyethylene resins, ethylene-vinyl acetate copolymer resins, etc. In particular, when the rubber component contains ethylene-α-olefin elastomers (EPDM, EPR), the thermoplastic resin R preferably contains polyethylene resins. Furthermore, when the rubber component has high polarity, such as nitrile rubber (NBR), the thermoplastic resin R preferably contains highly polar polyethylene resins modified by introducing polar groups such as maleic acid, nylon-based resins, urethane-based resins, etc.

[0024] The content of the nanofibers F in the composite material M is, for example, 30% by mass or more and 95% by mass or less. The number of the nanofibers F in the composite material M is, for example, 10 or more and 2000 or less.

[0025] Examples of carbon black include furnace blacks such as ISAF, HAF, MAF, FEF, SRF, GPF, and ECF. The carbon black preferably contains one or more of these, and more preferably contains ISAF from the viewpoint of obtaining excellent durability.

[0026] From the viewpoint of obtaining excellent durability, the arithmetic mean particle size of the carbon black is preferably 18 nm or more and 30 nm or less, more preferably 20 nm or more and 23 nm or less, and is determined as the number average of the particle sizes of 100 carbon black particles measured by electron microscope observation.

[0027] The nitrogen adsorption specific surface area of ​​the carbon black is preferably 95 m from the viewpoint of obtaining excellent durability. 2 / g or more 150m 2 / g or less, more preferably 115m 2 / g or more 125m 2 The nitrogen adsorption specific surface area of ​​carbon black is measured in accordance with JIS K6217-2:2017.

[0028] The carbon black content B in the uncrosslinked rubber composition Y is 25 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the rubber component, and from the viewpoint of obtaining excellent durability, it is preferably 30 parts by mass or more and 60 parts by mass or less, more preferably 35 parts by mass or more and 45 parts by mass or less.

[0029] From the viewpoint of obtaining excellent durability, the carbon black content B in the uncrosslinked rubber composition Y is preferably greater than the nanofiber content A. From the same viewpoint, the ratio (B / A) of the carbon black content B to the nanofiber content A is preferably 8 or more and 24 or less, more preferably 14 or more and 18 or less.

[0030] From the viewpoint of obtaining excellent durability, the content C of zinc dimethacrylate in the uncrosslinked rubber composition Y is preferably 0.5 parts by mass or more and 40 parts by mass or less, more preferably 1 part by mass or more and 30 parts by mass or less, and even more preferably 15 parts by mass or more and 25 parts by mass or less, per 100 parts by mass of the rubber component.

[0031] From the viewpoint of obtaining excellent durability, the zinc dimethacrylate content C in the uncrosslinked rubber composition Y is preferably greater than the nanofiber content A. From the same viewpoint, the ratio (C / A) of the zinc dimethacrylate content C to the nanofiber content A is preferably 4 or more and 16 or less, more preferably 6 or more and 10 or less.

[0032] From the viewpoint of obtaining excellent durability, the zinc dimethacrylate content C in the uncrosslinked rubber composition Y is preferably the same as or less than the carbon black content B. From the same viewpoint, the ratio (C / B) of the zinc dimethacrylate content C to the carbon black content B is preferably 0.01 or more and 1 or less, more preferably 0.4 or more and 0.6 or less.

[0033] The sum of the contents of carbon black and zinc dimethacrylate in the uncrosslinked rubber composition Y (B+C) is 35 parts by mass or more and 75 parts by mass or less per 100 parts by mass of the rubber component, and from the viewpoint of obtaining excellent durability, it is preferably 50 parts by mass or more and 65 parts by mass or less, more preferably 57 parts by mass or more and 63 parts by mass or less.

[0034] From the viewpoint of obtaining excellent durability, the uncrosslinked rubber composition Y preferably contains an amylphenol disulfide polymer as a co-crosslinking agent. From the viewpoint of obtaining excellent durability, the content D of the amylphenol disulfide polymer in the uncrosslinked rubber composition Y is preferably 0.2 parts by mass or more and 5 parts by mass or less, more preferably 0.5 parts by mass or more and 1.5 parts by mass or less, per 100 parts by mass of the rubber component.

[0035] From the viewpoint of obtaining excellent durability, the content D of the amylphenol disulfide polymer in the uncrosslinked rubber composition Y is preferably smaller than the content A of the nanofiber. From the same viewpoint, the ratio (D / A) of the content D of the amylphenol disulfide polymer to the content A of the nanofiber is preferably 0.1 or more and 0.8 or less, more preferably 0.3 or more and 0.5 or less.

[0036] From the viewpoint of obtaining excellent durability, the content D of the amylphenol disulfide polymer in the uncrosslinked rubber composition Y is preferably smaller than the content B of the carbon black. From the same viewpoint, the ratio (D / B) of the content D of the amylphenol disulfide polymer to the content B of the carbon black is preferably 0.01 or more and 0.1 or less, more preferably 0.02 or more and 0.03 or less.

[0037] From the viewpoint of obtaining excellent durability, the content D of the amylphenol disulfide polymer in the uncrosslinked rubber composition Y is preferably the same as or less than the content C of zinc dimethacrylate. From the same viewpoint, the ratio (D / C) of the content D of the amylphenol disulfide polymer to the content C of zinc dimethacrylate is preferably 0.03 or more and 1 or less, more preferably 0.04 or more and 0.06 or less.

[0038] In order to obtain excellent durability, the sum of the contents of zinc dimethacrylate and amylphenol disulfide polymer in the uncrosslinked rubber composition Y (C+D) is preferably 1.5 parts by mass or more and 40 parts by mass or less, more preferably 15 parts by mass or more and 25 parts by mass or less, per 100 parts by mass of the rubber component.

[0039] The uncrosslinked rubber composition Y preferably contains short fibers from the viewpoint of obtaining excellent durability. Examples of short fibers include para-aramid short fibers, meta-aramid short fibers, polyparaphenylene benzobisoxazole short fibers, nylon 6 short fibers, nylon 6,6 short fibers, nylon 4,6 short fibers, polyethylene terephthalate short fibers, and polyethylene naphthalate short fibers. The short fibers preferably contain one or more of these, and more preferably contain para-aramid short fibers from the viewpoint of obtaining excellent durability.

[0040] Examples of para-aramid staple fibers include polyparaphenylene terephthalamide staple fibers and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide staple fibers. Commercially available polyparaphenylene terephthalamide staple fibers include Twaron manufactured by Teijin Limited, and Kevlar 29, Kevlar 49, Kevlar 119, and Kevlar 129 manufactured by DuPont. Commercially available copolyparaphenylene-3,4'-oxydiphenylene terephthalamide staple fibers include Technora manufactured by Teijin Limited. The staple fibers are preferably fibrillated to exhibit a high reinforcing effect, and from this perspective, it is more preferable that the staple fibers contain polyparaphenylene terephthalamide staple fibers, which are easily fibrillated.

[0041] From the viewpoint of obtaining excellent durability, the fiber diameter d2 of the short fibers is preferably 5 μm or more and 50 μm or less, more preferably 11 μm or more and 13 μm or less. From the same viewpoint, the ratio of the fiber diameter d2 of the short fibers to the fiber diameter d1 of the nanofibers (d2 / d1) is preferably 10 or more and 70 or less, more preferably 15 or more and 20 or less. From the same viewpoint, the filament fineness of the short fibers is preferably 1 dtex or more and 5 dtex or less, more preferably 1.4 dtex or more and 1.6 dtex or less.

[0042] From the viewpoint of obtaining excellent durability, the fiber length l2 of the short fibers is preferably 1 mm or more and 10 mm or less, more preferably 2 mm or more and 3.5 mm or less. From the same viewpoint, the fiber length l2 of the short fibers is preferably longer than the fiber length l1 of the nanofibers. From the same viewpoint, the ratio of the fiber length l2 of the short fibers to the fiber length l1 of the nanofibers (l2 / l1) is preferably 1.1 or more and 5 or less, more preferably 2.5 or more and 3.5 or less.

[0043] From the viewpoint of obtaining excellent durability, the ratio of the fiber length l2 to the fiber diameter d2 of the short fibers (l2 / d2: aspect ratio) is preferably 20 to 700, more preferably 200 to 300. From the same viewpoint, the aspect ratio (l2 / d2) of the short fibers is preferably smaller than the aspect ratio (l1 / d1) of the nanofibers. From the same viewpoint, the ratio (l2 / d2 / l1 / d1) of the aspect ratio (l2 / d2) of the short fibers to the aspect ratio (l1 / d1) of the nanofibers is preferably 0.1 to 0.5, more preferably 0.15 to 0.2.

[0044] From the viewpoint of obtaining excellent durability, the content E of short fibers in the uncrosslinked rubber composition Y is preferably 20 parts by mass or more and 40 parts by mass or less, more preferably 25 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of the rubber component.

[0045] From the viewpoint of obtaining excellent durability, the short fiber content E in the uncrosslinked rubber composition Y is preferably greater than the nanofiber content A. From the same viewpoint, the ratio (E / A) of the short fiber content E to the nanofiber content A is preferably 10 or more and 16 or less, more preferably 11 or more and 12 or less.

[0046] From the viewpoint of obtaining excellent durability, the short fiber content E in the uncrosslinked rubber composition Y is preferably smaller than the carbon black content B. From the same viewpoint, the ratio (E / B) of the short fiber content E to the carbon black content B is preferably 0.45 or more and 0.95 or less, more preferably 0.6 or more and 0.8 or less.

[0047] In the uncrosslinked rubber composition Y, the ratio (E / C) of the short fiber content E to the zinc dimethacrylate content C is preferably 0.9 or more and 30 or less, more preferably 1.3 or more and 1.5 or less, from the viewpoint of obtaining excellent durability. From the same viewpoint, the short fiber content E is preferably larger than the zinc dimethacrylate content C.

[0048] In order to obtain excellent durability, the sum of the contents of the nanofibers and short fibers in the uncrosslinked rubber composition Y (A+E) is preferably 24 parts by mass or more and 45 parts by mass or less, more preferably 29 parts by mass or more and 33 parts by mass or less, per 100 parts by mass of the rubber component.

[0049] The uncrosslinked rubber composition Y may contain sulfur as a crosslinking agent, or may contain an organic peroxide, or may contain both sulfur and an organic peroxide. When the rubber component contains CR, the uncrosslinked rubber composition Y may contain a metal oxide such as magnesium oxide as a crosslinking agent.

[0050] The uncrosslinked rubber composition Y may also contain a thermoplastic resin R that constitutes the portion of the composite material M other than the nanofibers F, a plasticizer, a processing aid, and the like.

[0051] The contents of nanofibers, carbon black, para-aramid short fibers, etc. in the uncrosslinked rubber composition Y are substantially the same as those in the crosslinked rubber composition X. However, in the crosslinked rubber composition X, the co-crosslinking agent and crosslinking agent are incorporated into the rubber component for crosslinking or consumed for crosslinking of the rubber component. Therefore, the contents of the co-crosslinking agent and crosslinking agent are specified only in the uncrosslinked rubber composition Y before crosslinking.

[0052] The crosslinked rubber composition X forming the compressed rubber layer 111 is provided so that its grain direction corresponds to the belt width direction and its anti-grain direction corresponds to the belt length direction. Therefore, in the crosslinked rubber composition X, the nanofibers are dispersed in the rubber component and oriented in the grain direction. Furthermore, when the crosslinked rubber composition X contains short fibers, the short fibers are also dispersed in the rubber component and oriented in the grain direction.

[0053] From the viewpoint of obtaining excellent durability, the crosslinked rubber composition X has an elongation at break (EB) in the anti-grain direction at 25°C of preferably 60% or more and 100% or less, more preferably 65% ​​or more and 95% or less. The elongation at break (EB) is measured in accordance with JIS K6251:2017.

[0054] From the viewpoint of obtaining excellent durability, the vertical storage modulus E' of the crosslinked rubber composition X in the grain direction at 25°C is preferably 900 MPa or more, more preferably 920 MPa or more. This vertical storage modulus E' is measured by a tensile method based on JIS K6394:2007, where the average strain is the strain when a load 1.3 times the load at 1% strain is applied, the strain amplitude is 0.1%, the frequency is 10 Hz, and the test temperature is 25°C.

[0055] The tension rubber layer 112 and the adhesive rubber layer 113 are formed of a cross-linked rubber composition. The tension rubber layer 112 and the adhesive rubber layer 113 may be formed of the same cross-linked rubber composition X as the compression rubber layer 111.

[0056] The reinforcing fabric 12 is made of, for example, a woven fabric, a knitted fabric, or a nonwoven fabric made of synthetic or natural fibers. The reinforcing fabric 12 is preferably subjected to an adhesive treatment to impart adhesion to the belt body 11. Note that a reinforcing fabric of a similar configuration may also be provided to cover the outer peripheral surface of the tension rubber layer 112.

[0057] The core wires 13 are made of twisted yarns made of synthetic fibers, etc. The core wires 13 are preferably subjected to an adhesive treatment to impart adhesiveness to the belt body 11.

[0058] In the double-cogged V-belt B according to the embodiment described above, the crosslinked rubber composition X forming the compressed rubber layer 111, which constitutes the V-side surface 111a, is composed of a crosslinked product of an uncrosslinked rubber composition Y containing a rubber component, nanofibers, carbon black, and zinc dimethacrylate. In the crosslinked rubber composition X, the nanofibers are oriented in the belt width direction. In the uncrosslinked rubber composition Y, the carbon black content B is 25 to 70 parts by mass per 100 parts by mass of the rubber component, and the sum of the carbon black and zinc dimethacrylate contents (B + C) is 35 to 75 parts by mass, thereby achieving high performance. Specifically, excellent durability can be achieved whether the belt is running at low or high speeds.

[0059] 3A and 3B show a transmission 20 for a motorcycle or the like that uses a double-cogged V-belt B according to an embodiment.

[0060] The transmission 20 includes a drive pulley 21 and a driven pulley 22 that are arranged so that their rotation axes are parallel to each other. The double-cogged V-belt B according to the embodiment is wound between the drive pulley 21 and the driven pulley 22.

[0061] The drive pulley 21 and the driven pulley 22 each have fixed sheaves 211, 221 that are immovable in the axial direction and movable sheaves 212, 222 that are movable in the axial direction. A V-groove 23 into which the double-cogged V-belt B according to the embodiment is fitted is formed between the fixed sheaves 211, 221 and the movable sheaves 212, 222 of the drive pulley 21 and the driven pulley 22, respectively.

[0062] The V-groove 23 narrows in width as the movable sheaves 212, 222 move closer to the fixed sheaves 211, 221. At this time, the double-cogged V-belt B according to the embodiment is pushed up toward the outer periphery within the V-groove 23, increasing the winding diameter of the belt pitch lines L1, L2, i.e., the pulley diameter. On the other hand, the V-groove 23 widens in width as the movable sheaves 212, 222 move away from the fixed sheaves 211, 221. At this time, the double-cogged V-belt B according to the embodiment sinks inward within the V-groove 23, decreasing the pulley diameter.

[0063] With the above configuration, in this transmission device 20, the ratio of the pulley diameters of the drive pulley 21 and the driven pulley 22 is changed between a low-speed mode in which the pulley diameter of the drive pulley 21 is small and the pulley diameter of the driven pulley 22 is large, and a high-speed mode in which the pulley diameter of the drive pulley 21 is large and the pulley diameter of the driven pulley 22 is small, thereby continuously changing the rotational speed of the drive pulley 21 and transmitting it to the driven pulley 22 via the double-cog V-belt B.

[0064] Next, a method for manufacturing the double-cogged V-belt B according to the embodiment will be described with reference to FIGS. 4A to 4H and 5A to 5B.

[0065] <Component preparation process> In the component preparation process, first, a composite material M having a sea-island structure of a sea of ​​thermoplastic resin R and numerous islands of bundles of nanofibers F as shown in Figure 2 is blended and kneaded with a rubber component. During this process, the thermoplastic resin R of the composite material M melts and diffuses into the rubber component, and the nanofibers F are dispersed in the rubber component. Thereafter, carbon black, zinc dimethacrylate, and other rubber compounding ingredients are further blended and kneaded to prepare a block of uncrosslinked rubber composition Y.

[0066] Next, the block of uncrosslinked rubber composition Y is rolled to produce an uncrosslinked rubber sheet for forming the compressed rubber layer 111. In the uncrosslinked rubber sheet, the nanofibers are oriented in the grain direction, which is the rolling direction.

[0067] Similarly, an uncrosslinked rubber sheet for forming the tension rubber layer 112 and an uncrosslinked rubber sheet for forming the adhesive rubber layer 113 are also prepared. In addition, the reinforcing fabric 12 and the cord 13 are each subjected to a predetermined adhesive treatment.

[0068] <Molding / crosslinking process> In the molding and cross-linking step, first, as shown in Fig. 4A, the reinforcing fabric 12 and an uncross-linked rubber sheet 111' for forming the compressed rubber layer 111 are wound in this order onto the outer circumferential surface of the first cylindrical mold 311 to mold the lower cog molded body 40'. At this time, the reinforcing fabric 12 is provided so as to align with the lower cog forming grooves 311a that are continuously provided in the circumferential direction on the outer periphery of the first cylindrical mold 311. In addition, the uncross-linked rubber sheet 111' is provided so that its grain direction is the axial direction of the first cylindrical mold 311, and therefore the belt width direction.

[0069] Next, as shown in Fig. 4B, a first rubber sleeve 312 with a smooth inner surface is placed over the lower cog molded body 40' on the first cylindrical mold 311, and the resultant is placed in a vulcanizing can and sealed. At the same time, high-temperature, high-pressure steam is filled into the vulcanizing can and this state is maintained for a predetermined time. At this time, the uncrosslinked rubber sheet 111' flows and is pressed into the lower cog forming groove 311a, and the crosslinking progresses to about half and the reinforcing fabric 12 is combined with the lower cog C on the inner periphery as shown in Fig. 4C. LA cylindrical lower cog composite 40 is molded.

[0070] Next, the steam is released from inside the vulcanizing can to release the seal, the first cylindrical mold 311 is removed, the first rubber sleeve 312 is removed, and the can is cooled.After that, as shown in Figure 4D, the outer periphery of the lower cog complex 40 molded on the first cylindrical mold 311 is shaved with a blade to adjust the thickness.

[0071] Next, after the lower cog complex 40 is removed from the first cylindrical mold 311, it is fitted onto the second cylindrical mold 321 as shown in 4E. L The second cylindrical mold 321 is provided so as to fit into the lower cog fitting grooves 321a that are continuously provided in the circumferential direction on the outer periphery of the second cylindrical mold 321.

[0072] Next, as shown in Figure 4F, an uncrosslinked rubber sheet 113' for forming the adhesive rubber layer 113 is wrapped around the lower cog complex 40 on the second cylindrical mold 321, and then the core wire 13 is spirally wrapped around it, and then an uncrosslinked rubber sheet 113' for forming the adhesive rubber layer 113 and an uncrosslinked rubber sheet 112' for forming the tension rubber layer 112 are wrapped around it in sequence to form an uncrosslinked slab S'.

[0073] Next, as shown in FIG. 4G, the uncrosslinked slab S' is covered with a second rubber sleeve 322, which is then placed in a vulcanizer and sealed. High-temperature, high-pressure steam is then filled into the vulcanizer and maintained in this state for a predetermined period of time. At this time, the main crosslinking of the lower cog composite 40 progresses. At the same time, the uncrosslinked rubber sheet 113' for forming the adhesive rubber layer 113 also crosslinks and combines with the cords 13. The uncrosslinked rubber sheet 112' for forming the tension rubber layer 112 flows and is pressed into the upper cog forming grooves 322a arranged circumferentially on the inner periphery of the second rubber sleeve 322, and the crosslinking progresses. Finally, as shown in FIG. 4H, the entire assembly is integrated to form a cylindrical belt slab S.

[0074] <Width cutting and V-side forming process> The steam is discharged from the vulcanizer to release the seal, the second cylindrical mold 321 is taken out, the second rubber sleeve 322 is removed, and after cooling, the belt slab S is removed from the second cylindrical mold 321.

[0075] Then, as shown in FIG. 5A, the belt slab S is cut to a predetermined width, and then, as shown in FIG. 5B, both sides are cut with a blade to form V-sides 111a, thereby obtaining the double-cogged V-belt B according to the embodiment.

[0076] While the above embodiment illustrates a double-cogged V-belt B, the present invention is not limited thereto and may be a single-cogged V-belt having only lower cogs, or a raw-edge V-belt having no cogs. A V-ribbed belt in which the V-side surfaces of the V-ribs are formed from crosslinked rubber composition X may also be used, achieving the same effects as those of the above embodiment. Furthermore, a toothed belt or flat belt in which at least a portion of the belt body is formed from crosslinked rubber composition X may also be used, achieving high performance. Specifically, in these cases, crosslinked rubber composition X has nanofibers oriented in the belt width direction, providing relatively high rigidity in the belt width direction, thereby suppressing warpage in the belt width direction. Furthermore, its relatively low rigidity in the belt length direction allows it to be bent with little force and wound around a pulley, resulting in stable belt running performance over long periods of time. [Example]

[0077] (Crosslinked rubber composition and double cog V-belt) The crosslinked rubber compositions and double-cogged V-belts were prepared in the following Examples 1 to 4 and Comparative Examples 1 to 3. The respective configurations are also shown in Tables 1 and 2.

[0078] Example 1 The rubber component, EPDM (T7241, manufactured by JSR Corporation, ethylene content: 52% by mass, ENB content: 7.7% by mass), was charged into a Banbury mixer, and 3.6 parts by mass of a polyethylene resin-PET nanofiber composite material (Nanofront, manufactured by Teijin Frontier Co., Ltd.) was charged per 100 parts by mass of this rubber component, and they were kneaded at a temperature higher than the melting point of the polyethylene resin contained in the composite material. Then, 100 parts by mass of the rubber component was mixed with ISAF carbon black (Seast 6, manufactured by Tokai Carbon Co., Ltd., arithmetic mean particle size: 22 nm, nitrogen adsorption specific surface area: 119 m). 2 Further added were 40 parts by mass of cellulose acetate copolymer (cellulose acetate copolymer, cellulose acetate diol, cellulose acetate copolymer) (1 / g), 10 parts by mass of process oil (Sunper 2280, manufactured by Sun Oil Co., Ltd.), 0.25 parts by mass of stearic acid as a processing aid (Stearic Acid S50, manufactured by New Japan Chemical Co., Ltd.), 5 parts by mass of zinc oxide as a vulcanization accelerator aid (Zinc Oxide Type 3, manufactured by Sakai Chemical Co., Ltd.), 20 parts by mass of zinc dimethacrylate as a co-crosslinking agent (Acter ZMA, manufactured by Kawaguchi Chemical Industry Co., Ltd.), 1 part by mass of amylphenol disulfide polymer as a co-crosslinking agent (Suncerer AP, manufactured by Sanshin Chemical Industry Co., Ltd.), and 4 parts by mass of N,N'-m-phenylene bismaleimide as a co-crosslinking agent (Balnoc PM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), and the mixture was kneaded.

[0079] Next, the kneaded mass of uncrosslinked rubber composition was discharged from the Banbury mixer and cooled once, and then, relative to 100 parts by mass of the rubber component, 28 parts by mass of polyparaphenylene terephthalamide short fibers (Kevlar 119, manufactured by DuPont) which are para-aramid short fibers, 0.5 parts by mass of sulfur (Seimi OT, manufactured by Nippon Kanretsu Kogyo Co., Ltd.) as a crosslinking agent, and 7 parts by mass (2.8 parts by mass of active ingredient) of an organic peroxide (Peroximon F-40, manufactured by Nippon Oil & Fats Corporation, purity 40% by mass) as a crosslinking agent, and kneaded.

[0080] Subsequently, the kneaded mass of uncrosslinked rubber composition was discharged from the Banbury mixer and rolled with a calendar roll to obtain an uncrosslinked rubber sheet.

[0081] The uncrosslinked rubber sheet was then press-molded to produce a crosslinked rubber composition sheet. Furthermore, a double-cogged V-belt having the same configuration as the above embodiment was produced by forming a compressed rubber layer using the uncrosslinked rubber sheet. The crosslinked rubber composition sheet and the double-cogged V-belt were designated Example 1.

[0082] The composite material used above has a sea-island structure consisting of a sea of ​​polyethylene resin and 1200 islands of PET nanofibers.

[0083] The composite material contains 30% by mass of polyethylene resin and 70% by mass of nanofiber, so the polyethylene resin content is 1.1 parts by mass and the nanofiber content is 2.5 parts by mass per 100 parts by mass of the rubber component.

[0084] The outer diameter of the composite material is 30 μm and the length is 1 mm. Therefore, the fiber length l1 of the PET fiber nanofiber is 1 mm. The fiber diameter d1 is 700 nm. The fiber diameter d2 of the polyparaphenylene terephthalamide short fiber, a para-aramid short fiber, is 12 μm. The fiber length l2 is 3 mm.

[0085] The double-cogged V-belt's tension and adhesive rubber layers were made of a cross-linked rubber composition containing EPDM as the rubber component. The core wire was made of twisted PET fiber. The reinforcing fabric was made of woven PET fiber.

[0086] <Example 2> A sheet-shaped crosslinked rubber composition and a double-cogged V-belt were prepared in the same manner as in Example 1, except that N,N'-m-phenylenebismaleimide was not used. These were designated as Example 2.

[0087] Example 3 A sheet-shaped cross-linked rubber composition and a double-cogged V-belt were prepared in the same manner as in Example 1, except that the content of ISAF carbon black was 30 parts by mass per 100 parts by mass of the rubber component and the content of zinc dimethacrylate was also 30 parts by mass per 100 parts by mass of the rubber component, and these were designated Example 3.

[0088] Example 4 A sheet-shaped cross-linked rubber composition and a double-cogged V-belt were prepared in the same manner as in Example 1, except that the content of ISAF carbon black was 59 parts by mass per 100 parts by mass of the rubber component and the content of zinc dimethacrylate was 1 part by mass per 100 parts by mass of the rubber component, and these were designated Example 4.

[0089] <Comparative Example 1> A sheet-shaped crosslinked rubber composition and a double-cogged V-belt were prepared in the same manner as in Example 1, except that the polyethylene resin-PET nanofiber composite material, amylphenol disulfide polymer, and sulfur were not used, and these were designated Comparative Example 1.

[0090] <Comparative Example 2> A sheet-shaped cross-linked rubber composition and a double-cogged V-belt were prepared in the same manner as in Example 1, except that the content of zinc dimethacrylate was 40 parts by mass per 100 parts by mass of the rubber component and amylphenol disulfide polymer and sulfur were not used, and these were designated Comparative Example 2.

[0091] <Comparative Example 3> A sheet-shaped cross-linked rubber composition and a double-cogged V-belt were prepared in the same manner as in Example 1, except that the content of ISAF carbon black was 20 parts by mass per 100 parts by mass of the rubber component, the content of zinc dimethacrylate was 40 parts by mass per 100 parts by mass of the rubber component, and amylphenol disulfide polymer and sulfur were not used. These were designated Comparative Example 3.

[0092] [Table 1]

[0093] [Table 2]

[0094] (Test Method) <Elongation at break EB> For each of the sheet-shaped crosslinked rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 3, the elongation at break EB in the anti-grain direction at 25°C was measured based on JIS K6251:2017.

[0095] <Storage vertical elastic modulus E'> The fresh storage elastic modulus E' at 25°C of each of the sheet-shaped crosslinked rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 3 was measured by a tensile method based on JIS K6394: 2007. The measurement conditions were as follows: the average strain when a load 1.3 times the load at 1% strain was applied, a strain amplitude of 0.1%, a frequency of 10 Hz, and a test temperature of 25°C.

[0096] <Belt running test> 6A and 6B show a belt running tester 50. The belt running tester 50 includes a drive pulley 51 and a driven pulley 52. ​​Each of the drive pulley 51 and the driven pulley 52 is configured to vary the winding diameter at the center of the core wire of the double cog V-belt B to be tested. The driven pulley 52 is also configured to be able to apply a constant load DW (dead weight) to the double cog V-belt B so as to generate a constant belt tension.

[0097] For each of the double-cogged V-belts of Examples 1 to 4 and Comparative Examples 1 to 3, as shown in FIG. 6A, the double-cogged V-belt B was first wound around the drive pulley 51 so that the winding diameter at the center of the belt was 99 mm, and around the driven pulley 52 so that the winding diameter at the center of the belt was 263 mm. A constant load DW of 1800 N was applied to the driven pulley 52 to generate belt tension, creating a low-speed layout. The drive pulley 51 was then rotated at 7500 rpm in an ambient temperature of 30°C to start low-speed belt running. The double-cogged V-belt was then run until it broke, and the time from the start of belt running to breakage was defined as the low-speed belt life. The maximum belt running time was 200 hours.

[0098] As shown in FIG. 6B, a double-cogged V-belt B was wound around drive pulley 51 with a winding diameter of 210 mm at the center of its core wire, and around driven pulley 52 with a winding diameter of 165 mm at the center of its core wire. A constant load DW of 2300 N was applied to driven pulley 52 to generate belt tension, creating a high-speed layout. Then, in an ambient temperature of 100°C, drive pulley 51 was rotated at 9400 rpm to start high-speed belt running. The double-cogged V-belt was run until it broke, and the time from the start of belt running to breakage was defined as the high-speed belt life. The maximum belt running time was 50 hours.

[0099] (Test results) The test results are shown in Table 3. Table 3 shows that Examples 1 to 4 provide excellent durability at both low and high belt speeds. On the other hand, Comparative Examples 1 to 3 do not provide excellent durability at either low or high belt speeds.

[0100] [Table 3] [Industrial Applicability]

[0101] The present invention is useful in the technical field of power transmission belts. [Explanation of symbols]

[0102] B Double-cog V-belt (power transmission belt) C L Lower cog C U Upper cog M Composite material R Thermoplastic resin F nanofiber S' Uncross-linked slab S Belt Slab 11 Belt body 111 Compressed rubber layer 111', 112', 113' Uncrosslinked rubber sheet 111a V side 112 tension rubber layer 113 Adhesive rubber layer 12 Reinforcement fabric 13 Core Wire 20 Transmission 21 Drive pulley 211,221 Fixed sheave 212,222 Movable sheave 22 driven pulley 23 V groove 311 First cylindrical type 311a Lower cog forming groove 312 First rubber sleeve 321 Second cylindrical type 321a Lower cog fitting groove 322 Second rubber sleeve 322a Upper cog forming groove 40' Lower Cog Molded Body 40 Lower Cog Complex 50 Belt running test machine 51 Drive pulley 52 driven pulley

Claims

[Claim 1] A power transmission belt, at least a portion of which is made of a crosslinked rubber composition, the crosslinked rubber composition is composed of a crosslinked product of an uncrosslinked rubber composition containing a rubber component, nanofibers, carbon black, zinc dimethacrylate, and an amylphenol disulfide polymer, In the crosslinked rubber composition, the nanofibers are oriented in the belt width direction, In the uncrosslinked rubber composition, the content of the carbon black is 25 parts by mass or more and 70 parts by mass or less, and the sum of the contents of the carbon black and the zinc dimethacrylate is 35 parts by mass or more and 75 parts by mass or less, relative to 100 parts by mass of the rubber component.

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