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 transmission belt.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a high-performance transmission belt.

Means for Solving the Problems

[0005] The present invention is a transmission belt in which at least a part of a belt body is formed of 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, in the crosslinked rubber composition, the nanofibers are oriented in the belt width direction, and 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 with respect to 100 parts by mass of the rubber component.

Effects of the Invention

[0006] According to the present invention, a crosslinked rubber composition forming at least a part of a belt body is composed of a crosslinked product of an uncrosslinked rubber composition containing a rubber component, nanofibers, carbon black, and zinc dimethacrylate. In the crosslinked rubber composition, the nanofibers are oriented in the belt width direction. In the uncrosslinked rubber composition, the content of carbon black is 25 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component, and the sum of the contents of carbon black and zinc dimethacrylate is 35 parts by mass or more and 75 parts by mass or less, whereby high performance can be obtained.

Brief Description of the Drawings

[0007]

Figure 1A

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BEST MODE FOR CARRYING OUT THE INVENTION

[0008] Hereinafter, the embodiment will be described in detail.

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

[0010] The cross-sectional shape of the double cogged V-belt B according to the embodiment is formed such that the inner peripheral side portion is a trapezoid with the lower base shorter than the upper base, and the outer peripheral side portion is formed as a horizontally elongated rectangle. 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] On the inner peripheral side of the double cogged V-belt B according to the embodiment, there is a lower cog C Lare arranged at a constant pitch along the belt length direction. The lower cogs C L The longitudinal cross-sectional outline of is formed in a sine wave shape. On the outer peripheral side of the double-cogged V-belt B according to the embodiment, the upper cogs C U are arranged at a constant pitch along the belt length direction. The upper cogs C U The longitudinal cross-sectional outline of 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 member, a reinforcing cloth 12 made of a fiber member, and a core wire 13. The belt body 11 has an inner peripheral compression rubber layer 111, an outer peripheral extension rubber layer 112, and an adhesive rubber layer 113 therebetween. The reinforcing cloth 12 is provided to cover the inner peripheral surface of the compression rubber layer 111 to form the lower cogs C L are configured. The core wire 13 is embedded in the middle portion of the adhesive rubber layer 113 in the belt thickness direction and is provided to form a helix having a pitch in the belt width direction.

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

[0014] The compression rubber layer 111, which is a portion constituting the V-side surfaces 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 elastomers (EPDM, EPR), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber (H-NBR), and the like. The rubber component preferably contains one or more of these. 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, its 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, its diene component is preferably ethylidene norbornene (ENB) from the viewpoint of obtaining excellent durability, and its 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 nanofiber is a fine fiber with a fiber diameter d1 of 1 μm or less (1000 nm or less). The fiber diameter d1 of the nanofiber is preferably 300 nm or more and 1000 nm or less, more preferably 500 nm or more and 900 nm or less, from the viewpoint of obtaining excellent durability. The fiber length l1 of the nanofiber 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 l1 to the fiber diameter d1 of the nanofiber (l1 / d1: aspect ratio) is preferably 300 or more and 5000 or less, more preferably 1200 or more and 2000 or less, still more preferably 1350 or more and 1500 or less, from the same viewpoint.

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

[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, based on 100 parts by mass of the rubber component.

[0021] In the uncrosslinked rubber composition Y, it is preferable that the nanofibers are blended in the form of a composite material M having a sea-island structure of a sea of the thermoplastic resin R and a number of islands of an aggregate of nanofibers F as shown in FIG. 2 in the rubber component. In this case, since the thermoplastic resin R melts and diffuses into the rubber component by kneading in the uncrosslinked rubber composition Y, the nanofibers F will be contained in a state dispersed in the rubber component.

[0022] This composite material M is obtained by cutting conjugate fibers in which the nanofibers F exist independently and in parallel in an island shape in the sea polymer of the thermoplastic resin R into a rod shape. 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 l1 of the nanofibers F, 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 the thermoplastic resin R include a polyethylene resin, an ethylene-vinyl acetate copolymer resin, a nylon resin, a urethane resin, and the like. The thermoplastic resin R preferably contains one or more of these. Since the thermoplastic resin R diffuses into the rubber component during kneading, it preferably has high compatibility with the rubber component. Therefore, when the rubber component has low polarity, the thermoplastic resin R preferably contains a low-polarity polyethylene resin, an ethylene-vinyl acetate copolymer resin, or the like. In particular, when the rubber component contains an ethylene-α-olefin elastomer (EPDM, EPR), the thermoplastic resin R preferably contains a polyethylene resin. Further, when the rubber component has high polarity such as nitrile rubber (NBR), the thermoplastic resin R preferably contains a modified polyethylene resin obtained by introducing a polar group such as maleic acid, a nylon resin, a urethane resin, or the like.

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

[0025] Examples of the 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 average particle diameter 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. The arithmetic average particle diameter of the carbon black is determined as the number average of the particle diameters of 100 carbon black particles measured by electron microscope observation.

[0027] From the viewpoint of obtaining excellent durability, the nitrogen adsorption specific surface area of the carbon black is preferably 95 m 2 / g or more and 150 m 2 / g or less, more preferably 115 m 2125 m or more per g 2 It is 125 m2 / g or less. The nitrogen adsorption specific surface area of the carbon black is measured based on JIS K6217-2:2017.

[0028] The content B of carbon black in the unvulcanized rubber composition Y is 25 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component. 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] The content B of carbon black in the unvulcanized rubber composition Y is preferably more than the content A of nanofibers from the viewpoint of obtaining excellent durability. The ratio (B / A) of the content B of carbon black to the content A of nanofibers is preferably 8 or more and 24 or less, more preferably 14 or more and 18 or less, from the same viewpoint.

[0030] The content C of zinc dimethacrylate in the unvulcanized 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, still more preferably 15 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the rubber component, from the viewpoint of obtaining excellent durability.

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

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

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

[0035] From the viewpoint of obtaining excellent durability, the content D of the amylphenol disulfide polymer in the uncrosslinked rubber composition Y is preferably less than the content A of the nanofiber. 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, from the same viewpoint.

[0036] From the viewpoint of obtaining excellent durability, the content D of the amylphenol disulfide polymer in the uncrosslinked rubber composition Y is preferably less than the content B of the carbon black. 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, from the same viewpoint.

[0037] From the viewpoint of obtaining excellent durability, the content D of the amylphenol disulfide polymer in the unvulcanized 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] From the viewpoint of obtaining excellent durability, the sum (C + D) of the contents of zinc dimethacrylate and the amylphenol disulfide polymer in the unvulcanized rubber composition Y 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 with respect to 100 parts by mass of the rubber component.

[0039] From the viewpoint of obtaining excellent durability, the unvulcanized rubber composition Y preferably contains short fibers. Examples of the short fibers include para - aramid short fibers, meta - aramid short fibers, poly - paraphenylene benzobisoxazole short fibers, nylon 6 short fibers, nylon 6,6 short fibers, nylon 4,6 short fibers, polyethylene terephthalate short fibers, polyethylene naphthalate short fibers, etc. 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 the para - aramid short fibers include poly - paraphenylene terephthalamide short fibers and copoly - paraphenylene - 3,4’ - oxydiphenylene terephthalamide short fibers. Examples of the commercially available poly - paraphenylene terephthalamide short fibers include Twaron manufactured by Teijin Limited, and Kevlar 29, Kevlar 49, Kevlar 119, and Kevlar 129 manufactured by DuPont. Examples of the commercially available copoly - paraphenylene - 3,4’ - oxydiphenylene terephthalamide short fibers include Technora manufactured by Teijin Limited. The short fibers preferably fibrillate to exhibit a high reinforcing effect, and from this viewpoint, it is more preferable to contain poly - paraphenylene terephthalamide short fibers that 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 (d2 / d1) of the fiber diameter d2 of the short fibers to the fiber diameter d1 of the nanofibers is preferably 10 or more and 70 or less, more preferably 15 or more and 20 or less. From the same viewpoint, the fineness of the filaments 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, it is preferable that the fiber length l2 of the short fibers is longer than the fiber length l1 of the nanofibers. From the same viewpoint, the ratio (l2 / l1) of the fiber length l2 of the short fibers to the fiber length l1 of the nanofibers 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 (l2 / d2: aspect ratio) of the fiber length l2 of the short fibers to the fiber diameter d2 is preferably 20 or more and 700 or less, more preferably 200 or more and 300 or less. From the same viewpoint, it is preferable that the aspect ratio (l2 / d2) of the short fibers is 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 or more and 0.5 or less, more preferably 0.15 or more and 0.2 or less.

[0044] From the viewpoint of obtaining excellent durability, the content E of the 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 with respect to 100 parts by mass of the rubber component.

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

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

[0047] From the perspective of obtaining excellent durability, the ratio (E / C) of the content E of short fibers to the content C of zinc dimethacrylate in the unvulcanized rubber composition Y is preferably 0.9 or more and 30 or less, more preferably 1.3 or more and 1.5 or less. From the same perspective, the content E of short fibers is preferably greater than the content C of zinc dimethacrylate.

[0048] From the perspective of obtaining excellent durability, the sum (A + E) of the contents of nanofibers and short fibers in the unvulcanized rubber composition Y 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 with respect to 100 parts by mass of the rubber component.

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

[0050] In addition, the unvulcanized rubber composition Y may contain a thermoplastic resin R, a plasticizer, a processing aid, etc. that constitute the portion other than the nanofiber F in the composite material M.

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

[0052] The vulcanized rubber composition X forming the compression rubber layer 111 is provided such that its columnar direction corresponds to the belt width direction and its anti-columnar direction corresponds to the belt length direction, respectively. Therefore, in the vulcanized rubber composition X, the nanofibers are dispersed in the rubber component and oriented in the columnar direction. Also, when the vulcanized rubber composition X contains short fibers, the short fibers are also dispersed in the rubber component and oriented in the columnar direction.

[0053] The elongation at break EB in the anti-columnar direction of the vulcanized rubber composition X at 25°C is preferably 60% or more and 100% or less, more preferably 65% or more and 95% or less, from the viewpoint of obtaining excellent durability. This elongation at break EB is measured based on JIS K6251:2017.

[0054] The storage shear modulus E’ in the columnar direction of the vulcanized rubber composition X at 25°C is preferably 900 MPa or more, more preferably 920 MPa or more, from the viewpoint of obtaining excellent durability. This storage shear modulus E’ is measured by the tensile method with an average strain being the strain when a load 1.3 times the load at a strain of 1% is applied based on JIS K6394:2007, a strain amplitude of 0.1%, a frequency of 10 Hz, and a test temperature of 25°C.

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

[0056] The reinforcing cloth 12 is composed of, for example, a woven fabric, a knitted fabric, a non-woven fabric, etc. formed of synthetic fibers or natural fibers. It is preferable that the reinforcing cloth 12 is subjected to an adhesion treatment for imparting adhesiveness to the belt body 11. Note that a reinforcing cloth having a similar configuration may be provided so as to also cover the outer peripheral surface of the extension rubber layer 112.

[0057] The core wire 13 is composed of, for example, a twisted yarn formed of synthetic fibers. It is preferable that the core wire 13 is subjected to an adhesion treatment for imparting adhesiveness to the belt body 11.

[0058] According to the double cogged V-belt B according to the embodiment having the above configuration, the crosslinked rubber composition X that forms the compression rubber layer 111 which is a part constituting 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 content B of carbon black is 25 parts by mass or more and 70 parts by mass or less, and the sum (B + C) of the contents of carbon black and zinc dimethacrylate is 35 parts by mass or more and 75 parts by mass or less with respect to 100 parts by mass of the rubber component, whereby high performance can be obtained. Specifically, excellent durability can be obtained regardless of whether the belt runs at low speed or high speed.

[0059] Figs. 3A and 3B show a transmission 20 such as a motorcycle using the double cogged V-belt B according to the embodiment.

[0060] This transmission 20 includes a driving pulley 21 and a driven pulley 22 arranged such that their rotating shafts are parallel. And the double cogged V-belt B according to the embodiment is wound between those driving pulley 21 and driven pulley 22.

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

[0062] When the movable sheaves 212, 222 move in the direction approaching the fixed sheaves 211, 221, the groove width of the V-groove 23 becomes narrower. At this time, the double-cogged V-belt B according to the embodiment is pushed upward to the outer peripheral side within the V-groove 23, and the winding diameters of the belt pitch lines L1, L2, that is, the pulley diameters become larger. On the other hand, when the movable sheaves 212, 222 move in the direction away from the fixed sheaves 211, 221, the groove width of the V-groove 23 becomes wider. At this time, the double-cogged V-belt B according to the embodiment sinks into the inner peripheral side within the V-groove 23 and the pulley diameter becomes smaller.

[0063] With the above configuration, in this speed change device 20, 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, the ratio of the pulley diameters of the drive pulley 21 and the driven pulley 22 is changed, and thereby, via the double-cogged V-belt B, the rotational speed of the drive pulley 21 is continuously speed-changed and transmitted to the driven pulley 22.

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

[0065] <Member preparation process> In the member 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 Fig. 2 is blended and kneaded with a rubber component. At this time, 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 agents 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. Note that 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 core wire 13 are each subjected to a predetermined adhesion treatment.

[0068] <Molding / crosslinking process> In the molding and cross-linking process, first, as shown in Fig. 4A, the reinforcing cloth 12 and the uncross-linked rubber sheet 111' for forming the compressed rubber layer 111 are wound in that order on the outer circumferential surface of the first cylindrical mold 311 to mold the lower cog molded body 40'. At this time, the reinforcing cloth 12 is provided so as to be aligned 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. Also, 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, the lower cog molded body 40' on the first cylindrical mold 311 is covered with a first rubber sleeve 312 having a smooth inner surface, which is then placed in a vulcanizing can and sealed, and the vulcanizing can is filled with high-temperature, high-pressure steam and maintained in this state for a predetermined period of time. At this time, the uncrosslinked rubber sheet 111' flows and is pressed into the lower cog forming groove 311a, and the crosslinking proceeds to about half and is combined with the reinforcing cloth 12, forming the lower cog C on the inner periphery as shown in Fig. 4C. LThe formed cylindrical lower cog complex 40 is molded.

[0070] Next, steam is discharged from the vulcanizing can to release the seal, the first cylindrical mold 311 is taken out and the first rubber sleeve 312 is removed and cooled. Then, as shown in FIG. 4D, the outer peripheral portion 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 demolding the lower cog complex 40 from the first cylindrical mold 311, as shown in FIG. 4E, it is externally fitted onto the second cylindrical mold 321. At this time, the lower cog complex 40 is provided so that its lower cog C L fits into the lower cog fitting groove 321a continuously provided in the circumferential direction on the outer periphery of the second cylindrical mold 321.

[0072] Next, as shown in FIG. 4F, an unvulcanized rubber sheet 113' for forming the adhesive rubber layer 113 is wound around the lower cog complex 40 on the second cylindrical mold 321, the core wire 13 is spirally wound thereon, and then an unvulcanized rubber sheet 113' for forming the adhesive rubber layer 113 and an unvulcanized rubber sheet 112' for forming the extension rubber layer 112 are sequentially wound thereon to form an unvulcanized slab S'.

[0073] Next, as shown in FIG. 4G, the second rubber sleeve 322 is placed over the unvulcanized slab S', it is placed in the vulcanizing can and sealed, and the vulcanizing can is filled with high-temperature and high-pressure steam and maintained in that state for a predetermined time. At this time, the main crosslinking of the lower cog complex 40 proceeds. At the same time, the crosslinking of the unvulcanized rubber sheet 113' for forming the adhesive rubber layer 113 also proceeds and it is compounded with the core wire 13. Further, the unvulcanized rubber sheet 112' for forming the extension rubber layer 112 flows and is press-fitted into the upper cog forming groove 322a continuously provided in the circumferential direction on the inner periphery of the second rubber sleeve 322, and its crosslinking proceeds. Then, as shown in FIG. 4H, the whole is integrated to form a cylindrical belt slab S.

[0074] <Width cutting · V-side surface forming process> Discharge the steam from the vulcanizer to relieve the seal, remove the second cylindrical part 321 and take off the second rubber sleeve 322, then cool them, and demold the belt slab S from the second cylindrical part 321.

[0075] Then, as shown in FIG. 5A, after trimming the belt slab S to a predetermined width, as shown in FIG. 5B, cut both side surfaces with a blade to form the V-side surfaces 111a, thereby obtaining the double-cogged V-belt B according to the embodiment.

[0076] In the above embodiment, the double-cogged V-belt B is shown, but it is not particularly limited thereto. It may be a single-cogged V-belt having only a lower cog, or a raw-edge V-belt having no cog. Further, it may be a V-ribbed belt in which the portion constituting the V-side surface of the V-rib is formed of the crosslinked rubber composition X, and the same operational effects as those of the above embodiment can be obtained. Furthermore, it may be a toothed belt or a flat belt in which at least a part of the belt body is formed of the crosslinked rubber composition X, and high performance can be obtained. Specifically, in these cases, since the nanofibers are oriented in the belt width direction and the crosslinked rubber composition X has relatively high rigidity in the belt width direction, warpage in the belt width direction can be suppressed, and since it has relatively low rigidity in the belt length direction, it can be bent with a small force and wound around a pulley. As a result, stable belt running performance can be obtained over a long period of time.

Example

[0077] (Crosslinked Rubber Composition and Double-Cogged V-Belt) The crosslinked rubber compositions and double-cogged V-belts of Examples 1 to 4 and Comparative Examples 1 to 3 below were prepared. The respective configurations are also shown in Tables 1 and 2.

[0078] <Example 1> The rubber component EPDM (T7241, manufactured by JSR, ethylene content: 52% by mass, ENB content: 7.7% by mass) was added to 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 added per 100 parts by mass of the rubber component, and they were kneaded at a temperature higher than the melting point of the polyethylene resin contained in the composite material. Then, ISAF carbon black (Seat 6, manufactured by Tokai Carbon Co., Ltd., arithmetic mean particle size: 22 nm, nitrogen adsorption specific surface area: 119 m) was added per 100 parts by mass of the rubber component. 2 Further added were 40 parts by mass of toluene (1 / g), 10 parts by mass of process oil (Samper 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 3 types, manufactured by Sakai Chemical Co., Ltd.), 20 parts by mass of zinc dimethacrylate as a co-crosslinking agent (Actor 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 (Bulnoc PM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), and they were kneaded.

[0079] Next, the kneaded mass of the uncrosslinked rubber composition was discharged from the Banbury mixer and cooled once, and then it was again charged into the Banbury mixer together with 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 crosslinking agent (Peroximon F-40, manufactured by Nippon Oil & Fats Co., Ltd., purity 40% by mass) per 100 parts by mass of the rubber component, and kneaded.

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

[0081] Then, the obtained uncrosslinked rubber sheet was press-molded to produce a sheet-like crosslinked rubber composition. Also, a double-cogged V-belt having the same configuration as that of the above-described embodiment in which a compression rubber layer was formed using the obtained uncrosslinked rubber sheet was produced. These sheet-like crosslinked rubber compositions and double-cogged V-belts were designated as Example 1.

[0082] Here, the composite material used above has a sea-island structure of a sea of polyethylene resin and islands of 1200 PET fiber nanofibers.

[0083] The content of the polyethylene resin in the composite material is 30% by mass and the content of the nanofibers is 70% by mass. Therefore, the content of the polyethylene resin with respect to 100 parts by mass of the rubber component is 1.1 parts by mass and the content of the nanofibers is 2.5 parts by mass.

[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 nanofibers is 1 mm. The fiber diameter d1 is 700 nm. The fiber diameter d2 of the para-aramid short fibers, poly(p-phenylene terephthalamide) short fibers, is 12 μm. The fiber length l2 is 3 mm.

[0085] Also, the extension rubber layer and the adhesive rubber layer of the double-cogged V-belt were formed of a crosslinked rubber composition containing EPDM as a rubber component. The core wire was composed of a twisted yarn of PET fibers. The reinforcing fabric was composed of a woven fabric of PET fibers.

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

[0087] <Example 3> A sheet-like crosslinked rubber composition and a double cogged V-belt were produced in the same manner as in Example 1, except that the content of ISAF carbon black was 30 parts by mass with respect to 100 parts by mass of the rubber component, and the content of zinc dimethacrylate was also 30 parts by mass with respect to 100 parts by mass of the rubber component, and these were designated as Example 3.

[0088] <Example 4> A sheet-like crosslinked rubber composition and a double cogged V-belt were produced in the same manner as in Example 1, except that the content of ISAF carbon black was 59 parts by mass with respect to 100 parts by mass of the rubber component, and the content of zinc dimethacrylate was 1 part by mass with respect to 100 parts by mass of the rubber component, and these were designated as Example 4.

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

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

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

[0092]

Table 1

[0093] [Table 2]

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

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

[0096] <Belt running test> Figures 6A and B show a belt running test machine 50. The belt running test machine 50 includes a driving pulley 51 and a driven pulley 52. Each of the driving pulley 51 and the driven pulley 52 is configured such that the winding diameter at the center position of the core wire of the double-cogged V-belt B to be tested is variable. Further, the driven pulley 52 is configured to be able to load a constant belt tension DW (dead weight) to the double-cogged V-belt B.

[0097] For each of the double-cogged V-belts of Examples 1 to 4 and Comparative Examples 1 to 3, first, as shown in FIG. 6A, the double-cogged V-belt B was wound around the driving pulley 51 so that the winding diameter at the center position of its core wire was 99 mm, and was wound around the driven pulley 52 so that the winding diameter at the center position of its core wire was 263 mm. Then, a constant load DW of 1800 N was applied to the driven pulley 52 to generate a belt tension, thereby constituting a low-speed layout. Thereafter, at an ambient temperature of 30°C, the driving pulley 51 was rotated at 7500 rpm to start low-speed belt running. Then, the belt was run until the double-cogged V-belt was cut, and the time from the start of belt running to cutting was defined as the low-speed belt life. Note that the maximum belt running time was set to 200 hours.

[0098] Also, as shown in FIG. 6B, the double-cogged V-belt B was wound around the driving pulley 51 so that the winding diameter at the center position of its core wire was 210 mm, and was wound around the driven pulley 52 so that the winding diameter at the center position of its core wire was 165 mm. Then, a constant load DW of 2300 N was applied to the driven pulley 52 to generate a belt tension, thereby constituting a high-speed layout. Thereafter, at an ambient temperature of 100°C, the driving pulley 51 was rotated at 9400 rpm to start high-speed belt running. Then, the belt was run until the double-cogged V-belt was cut, and the time from the start of belt running to cutting was defined as the high-speed belt life. Note that the maximum belt running time was set to 50 hours.

[0099] (Test Results) The test results are shown in Table 3. According to Table 3, it can be seen that according to Examples 1 to 4, excellent durability can be obtained in both low-speed and high-speed belt running. On the other hand, it can be seen that in Comparative Examples 1 to 3, excellent durability has not been obtained in either low-speed or high-speed belt running.

[0100]

Table 3

Industrial Applicability

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

Explanation of Signs

[0102] B double cogged V-belt (transmission belt) C L Lower cog C U Upper cog M Composite material R Thermoplastic resin F Nanofiber S’ Unvulcanized slab S Belt slab 11 Belt body 111 Compression rubber layer 111’, 112’, 113’ Unvulcanized rubber sheet 111a V side 112 Extension rubber layer 113 Adhesive rubber layer 12 Reinforcing cloth 13 Core wire 20 Transmission 21 Driving 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 formed body 40 Lower cog composite 50 Belt running tester 51 Driving pulley 52 Driven pulley

Claims

【Claim 1】 A transmission belt in which at least a part of the belt body is formed of a crosslinked rubber composition, wherein 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, and 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 with respect to 100 parts by mass of the rubber component. A transmission belt.

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