JP2022152626A - transmission belt - Google Patents

Abstract

To provide a high-performance transmission belt.SOLUTION: In a transmission belt B, at least a portion 111 of a belt body 11 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, and zinc dimethacrylate. In the crosslinked rubber composition, the nanofibers are oriented in a belt width direction. In the uncrosslinked rubber composition, the content of the carbon black is 25 pts.mass or more and 70 pts.mass or less, and the sum of the contents of the carbon black and the zinc dimethacrylate is 35 pts.mass or more and 75 pts.mass or less, with respect to 100 pts.mass of the rubber component.SELECTED DRAWING: Figure 1A

Description

The present invention relates to power transmission belts.

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

Patent No. 6145170

An object of the present invention is to provide a high performance power transmission belt.

The present invention provides a power transmission belt in which at least a portion of the belt body is formed of a crosslinked rubber composition, the crosslinked 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, and in the uncrosslinked rubber composition, 100 parts by mass of the rubber component contains On the other hand, 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.

According to the present invention, the crosslinked rubber composition forming at least a portion of the 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, and in the uncrosslinked rubber composition, the carbon black content is 25 parts by mass or more and 70 parts by mass with respect to 100 parts by mass of the rubber component. parts or less 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, high performance can be obtained.

1 is a perspective view of one piece of a double cogged V-belt according to an embodiment; FIG. 1 is a partial vertical cross-sectional view of a double cogged V-belt according to an embodiment; FIG. 1 is a cross-sectional view of a double cogged V-belt according to an embodiment; FIG. 1 is a perspective view of a composite material; FIG. 1 is a cross-sectional view showing the configuration of a transmission using a double-cogged V-belt according to an embodiment; FIG. 1 is a longitudinal sectional view showing the configuration of a transmission using a double-cogged V-belt according to an embodiment; FIG. FIG. 4 is a first explanatory diagram of a forming/crosslinking step in the method for manufacturing the double cogged V-belt of the embodiment; FIG. 4 is a second explanatory view of the molding and cross-linking steps in the method for manufacturing the double cogged V-belt of the embodiment; FIG. 11 is a third explanatory view of the molding and cross-linking steps in the method for manufacturing the double cogged V-belt of the embodiment; FIG. 10 is a fourth explanatory view of the forming and cross-linking steps in the method for manufacturing the double cogged V-belt of the embodiment; FIG. 11 is a fifth explanatory view of the forming/crosslinking step in the method for manufacturing the double cogged V-belt of the embodiment; FIG. 11 is a sixth explanatory view of the forming/crosslinking step in the method for manufacturing the double cogged V-belt of the embodiment; FIG. 10 is a seventh explanatory view of the molding and cross-linking steps in the method for manufacturing the double cogged V-belt of the embodiment. FIG. 11 is an eighth explanatory view of the molding and cross-linking steps in the method for manufacturing the double-cogged V-belt of the embodiment; FIG. 4 is a first explanatory view of a width cutting/V side surface forming step in the method of manufacturing the double cogged V-belt of the embodiment; FIG. 11 is a second explanatory view of the width cutting/V side surface forming step in the method of manufacturing the double cogged V-belt of the embodiment; It is a figure which shows the low speed layout of a belt running test machine. It is a figure which shows the high-speed layout of a belt running test machine.

Hereinafter, embodiments will be described in detail.

1A to 1C 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 transmissions of motorcycles, four-wheeled vehicles, or other general-purpose machines.

The cross-sectional shape of the double cogged V-belt B according to the embodiment is such that the inner peripheral side portion is formed into a trapezoid whose lower base is shorter than the upper base, and the outer peripheral side portion is formed into a laterally elongated rectangular shape. . 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.

On the inner peripheral side of the double cogged _V -belt B according to the embodiment, lower cogs CL are arranged at a constant pitch along the belt length direction. The longitudinal cross- _sectional profile of the lower cog CL is formed in a sinusoidal shape. On the outer peripheral side of the double cogged V-belt B according to the embodiment, upper _cogs CU are arranged at a constant pitch along the belt length direction. The longitudinal cross- _sectional profile of the upper cog CU is formed in a trapezoidal shape.

The double-cogged V-belt B according to the embodiment includes a belt body 11 made of a rubber member, and reinforcing cloth 12 and cords 13 made of fiber members. The belt body 11 has a compression rubber layer 111 on the inner circumference side, a stretch rubber layer 112 on the outer circumference side, and an adhesive rubber layer 113 therebetween. The reinforcing cloth 12 is provided so as to cover the inner peripheral surface of the compression rubber layer 111 and constitute the lower _cog CL. The core wire 13 is embedded in the intermediate portion 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.

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

The compression rubber layer 111, which constitutes the V side surface 111a, is made of the crosslinked rubber composition X. As shown in FIG. The crosslinked rubber composition X is composed of a crosslinked product of the uncrosslinked rubber composition Y.

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

Examples of rubber components include ethylene-α-olefin elastomers (EPDM, EPR), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), and hydrogenated acrylonitrile rubber (H-NBR). The rubber component preferably contains one or more of these, and from the viewpoint of obtaining excellent durability, it may contain ethylene-α-olefin elastomer (EPDM, EPR) or chloroprene rubber (CR). more preferred.

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. be. When the rubber component contains EPDM, its diene component is preferably ethylidene norbornene (ENB) from the viewpoint of obtaining excellent durability, and the diene content (ENB content) is preferably 6 from the same viewpoint. % by mass or more and 12% by mass or less, more preferably 7% by mass or more and 8% by mass or less.

Nanofibers are fine fibers with 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 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 same viewpoint, 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 l ₁ of the nanofiber to the fiber diameter d ₁ (l ₁ /d ₁ : aspect ratio) is preferably 300 or more and 5000 or less, more preferably 1200 or more and 2000 or less, and still more preferably 1350. 1500 or less.

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

From the viewpoint of obtaining excellent durability, the content A of the 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 with respect to 100 parts by mass of the rubber component. It is more than 3 mass parts or less.

The uncrosslinked rubber composition Y is in the form of a composite material M in which nanofibers have a sea-island structure of a large number of islands of a sea of thermoplastic resin R and bundles of nanofibers F as shown in FIG. Blending is preferred. In this case, the uncrosslinked rubber composition Y contains the nanofibers F dispersed in the rubber component because the thermoplastic resin R is melted by kneading and diffused into the rubber component.

This composite material M is obtained by cutting a conjugate fiber, in which nanofibers F exist independently and parallel to each other in the form of islands in a sea polymer of a 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.

Examples of thermoplastic resins R include polyethylene resins, ethylene-vinyl acetate copolymer resins, nylon-based resins, urethane-based resins, 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 is preferable that the thermoplastic resin R has high compatibility with the rubber component. Therefore, when the rubber component has low polarity, the plastic resin R preferably contains low-polarity polyethylene resin, ethylene-vinyl acetate copolymer resin, or the like. Especially when the rubber component contains an ethylene-α-olefin elastomer (EPDM, EPR), the thermoplastic resin R preferably contains a polyethylene resin. In addition, when the rubber component is highly polar such as nitrile rubber (NBR), the thermoplastic resin R is a highly polar polyethylene resin modified by introducing a polar group such as maleic acid, a nylon resin, It is preferable to contain urethane-based resin or the like.

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 nanofibers F in the composite material M is, for example, 10 or more and 2000 or less.

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

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

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

The content B of carbon black in the uncrosslinked 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, and from the viewpoint of obtaining excellent durability, it is preferably 30 parts by mass or more and 60 parts by mass. Parts by mass or less, more preferably 35 parts by mass or more and 45 parts by mass or less.

The carbon black content B in the uncrosslinked rubber composition Y is preferably larger than the nanofiber content A from the viewpoint of obtaining excellent durability. 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.

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 100 parts by mass of the rubber component. is 1 part by mass or more and 30 parts by mass or less, more preferably 15 parts by mass or more and 25 parts by mass or less.

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

The content C of zinc dimethacrylate in the uncrosslinked rubber composition Y is preferably the same as the content B of carbon black or less than the content B of carbon black from the viewpoint of obtaining excellent durability. 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. be.

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. Therefore, it is preferably from 50 parts by mass to 65 parts by mass, more preferably from 57 parts by mass to 63 parts by mass.

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 with respect to 100 parts by mass of the rubber component. More preferably, it is 0.5 parts by mass or more and 1.5 parts by mass or less.

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 nanofibers. From the same viewpoint, the ratio (D/A) of the content D of the amylphenol disulfide polymer to the content A of the nanofibers is preferably 0.1 to 0.8, more preferably 0.3 to 0. .5 or less.

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 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. 0.03 or less.

From the viewpoint of obtaining excellent durability, the content D of the amylphenol disulfide polymer in the uncrosslinked rubber composition Y is the same as the content C of zinc dimethacrylate, or more than the content C of zinc dimethacrylate. is preferably less. 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. 0.06 or less.

From the viewpoint of obtaining excellent durability, the sum (C+D) of the content of zinc dimethacrylate and polymerized amylphenol disulfide in the uncrosslinked rubber composition Y is preferably 1.0% per 100 parts by mass of the rubber component. 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.

The uncrosslinked rubber composition Y preferably contains short fibers from the viewpoint of obtaining excellent durability. Examples of staple fibers include para-aramid staple fibers, meta-aramid staple fibers, polyparaphenylenebenzobisoxazole staple fibers, nylon 6 staple fibers, nylon 6,6 staple fibers, nylon 4,6 staple fibers, and polyethylene terephthalate staple fibers. fibers, polyethylene naphthalate short fibers, and the like. 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.

Para-aramid staple fibers include polyparaphenylene terephthalamide staple fibers and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide staple fibers. Commercially available polyparaphenylene terephthalamide staple fibers include, for example, Twaron from Teijin and Kevlar 29, Kevlar 49, Kevlar 119, and Kevlar 129 from DuPont. Commercially available copoly-paraphenylene-3,4'-oxydiphenylene terephthalamide staple fibers include Technora manufactured by Teijin Limited. The short fibers are preferably fibrillated to exhibit a high reinforcing effect, and from this point of view, it is more preferable to include polyparaphenylene terephthalamide short fibers that are easily fibrillated.

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 (d ₂ /d ₁ ) of the fiber diameter d ₂ of the short fibers to the fiber diameter d ₁ 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 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.

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 _point of view, 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 l ₂ of the short fibers to the fiber length l ₁ of the nanofibers (l ₂ /l ₁ ) is preferably 1.1 or more and 5 or less, more preferably 2.5 or more and 3.5. It is below.

The ratio of the fiber length l ₂ of the short fibers to the fiber diameter d ₂ (l ₂ /d ₂ : aspect ratio) is preferably 20 or more and 700 or less, more preferably 200 or more and 300 or less, from the viewpoint of obtaining excellent durability. be. From the same point of view, the aspect ratio (l ₂ /d ₂ ) of the short fibers is preferably smaller than the aspect ratio (l ₁ /d ₁ ) of the nanofibers. From the same viewpoint, the ratio (l ₂ /d ₂ /l ₁ /d ₁ ) of the aspect ratio (l ₂ /d ₂ ) of the short fibers to the aspect ratio (l ₁ /d ₁ ) of the nanofibers is preferably 0. 0.1 or more and 0.5 or less, more preferably 0.15 or more and 0.2 or less.

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 with respect to 100 parts by mass of the rubber component. It is more than 30 mass parts or less.

The content E of short fibers in the uncrosslinked rubber composition Y is preferably larger than the content A of nanofibers from the viewpoint of obtaining excellent durability. From the same viewpoint, the ratio (E/A) of the content E of the short fibers to the content A of the nanofibers is preferably 10 or more and 16 or less, more preferably 11 or more and 12 or less.

The content E of short fibers in the uncrosslinked rubber composition Y is preferably less than the content B of carbon black from the viewpoint of obtaining excellent durability. 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. be.

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

From the viewpoint of obtaining excellent durability, the sum (A+E) of the content of nanofibers and short fibers in the uncrosslinked rubber composition Y is preferably 24 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the rubber component. , more preferably 29 parts by mass or more and 33 parts by mass or less.

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

In addition, the uncrosslinked rubber composition Y may contain a thermoplastic resin R, a plasticizer, a processing aid, etc., which constitute parts of the composite material M other than the nanofibers F.

The contents of nanofibers, carbon black, para-aramid short fibers, etc. in the uncrosslinked rubber composition Y substantially match the contents in the crosslinked rubber composition X. However, in the crosslinked rubber composition X, the co-crosslinking agent and the crosslinker are incorporated into the rubber component for cross-linking or consumed for cross-linking of the rubber component. Therefore, the contents of the co-crosslinking agent and the cross-linking agent are specified only in the uncrosslinked rubber composition Y before cross-linking.

The cross-linked rubber composition X forming the compression rubber layer 111 is provided so that its grain direction corresponds to the belt width direction and its reverse 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. Moreover, 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.

From the viewpoint of obtaining excellent durability, the cross-linked rubber composition X has an elongation at break EB in the opposite grain direction at 25° C. of preferably 60% or more and 100% or less, more preferably 65% or more and 95% or less. This elongation at break EB is measured based on JIS K6251:2017.

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

The extension rubber layer 112 and the adhesive rubber layer 113 are made of a crosslinked rubber composition. The tension rubber layer 112 and the adhesive rubber layer 113 may be formed of the same crosslinked rubber composition X as the compression rubber layer 111 .

The reinforcing cloth 12 is composed of, for example, a woven cloth, a knitted cloth, a nonwoven cloth, or the like made of synthetic fibers or natural fibers. It is preferable that the reinforcement cloth 12 is subjected to an adhesion treatment for imparting adhesion to the belt body 11 . A reinforcing cloth having a similar structure may be provided so as to cover the outer peripheral surface of the elastic rubber layer 112 as well.

The core wire 13 is composed of twisted yarn or the like 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 .

According to the double-cogged V-belt B according to the embodiment having the above configuration, the crosslinked rubber composition X forming the compressed rubber layer 111, which is the portion constituting the V-side surface 111a, contains the rubber component, nanofibers, and carbon black. , and zinc dimethacrylate. In the crosslinked rubber composition X, the nanofibers are oriented in the belt width direction. , With respect to 100 parts by mass of the rubber component, the content B of carbon black is 25 parts by mass or more and 70 parts by mass or less, and the sum of the contents of carbon black and zinc dimethacrylate (B + C) is 35 parts by mass or more and 75 High performance can be obtained by setting the amount to parts by mass or less. Specifically, excellent durability can be obtained regardless of whether the belt runs at low speed or high speed.

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

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

The drive pulley 21 and the driven pulley 22 have axially immovable fixed sheaves 211 and 221 and axially movable movable sheaves 212 and 222, respectively. Between the fixed sheaves 211, 221 and the movable sheaves 212, 222 of the drive pulley 21 and the driven pulley 22, respectively, a V groove 23 is formed in which the double cogged V belt B according to the embodiment is fitted. .

The groove width of the V groove 23 becomes narrower as the movable sheaves 212 and 222 move closer to the fixed sheaves 211 and 221 . At this time, the double-cogged V-belt B according to the embodiment is pushed up in the V-groove 23 to the outer peripheral side, and the winding diameter of the belt pitch lines L1 and L2, that is, the pulley diameter, increases. On the other hand, when the movable sheaves 212 and 222 move away from the fixed sheaves 211 and 221, the width of the V groove 23 increases. At this time, the double-cogged V-belt B according to the embodiment sinks toward the inner peripheral side in the V-groove 23 and the pulley diameter becomes smaller.

With the above configuration, the transmission 20 has a low speed mode in which the drive pulley 21 has a small pulley diameter and the driven pulley 22 has a large pulley diameter, and a high speed mode in which the drive pulley 21 has a large pulley diameter and the driven pulley 22 has a small pulley diameter. mode, the ratio of the pulley diameters of the drive pulley 21 and the driven pulley 22 is changed, thereby continuously changing the rotation speed of the drive pulley 21 to the driven pulley 22 via the double-cogged V-belt B. introduce.

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.

<Member preparation process>
In the member preparation step, first, a composite material M having a sea-island structure of a sea of thermoplastic resin R and a large number of islands of bundles of nanofibers F shown in FIG. 2 is blended with a rubber component and kneaded. At this time, the thermoplastic resin R of the composite material M is melted and diffused into the rubber component, and the nanofibers F are dispersed into the rubber component. Thereafter, carbon black, zinc dimethacrylate, and other rubber compounding agents are further blended and kneaded to prepare an uncrosslinked rubber composition Y in the form of a block.

Next, by rolling the lumpy uncrosslinked rubber composition Y, an uncrosslinked rubber sheet for forming the compressed rubber layer 111 is produced. In the uncrosslinked rubber sheet, the nanofibers are oriented in the grain direction, which is the rolling direction.

Similarly, an uncrosslinked rubber sheet for forming the extension rubber layer 112 and an uncrosslinked rubber sheet for forming the adhesive rubber layer 113 are also produced. Further, the reinforcing cloth 12 and the core wire 13 are each subjected to a predetermined bonding process.

<Molding/crosslinking process>
In the molding/crosslinking step, first, as shown in FIG. 4A, the uncrosslinked rubber sheet 111' for forming the reinforcing cloth 12 and the compression rubber layer 111 is wound in order on the outer peripheral surface of the first cylindrical mold 311. A cog molded body 40' is molded. At this time, the reinforcing cloth 12 is provided along the lower cog forming grooves 311a that are continuous in the circumferential direction of the outer circumference of the first cylindrical mold 311. As shown in FIG. Also, the uncrosslinked rubber sheet 111' is provided so that its grain direction is the axial direction of the first cylindrical mold 311, ie, the belt width direction.

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 peripheral surface, which is placed in a vulcanization can and sealed. At the same time, the vulcanizing can is filled with high-temperature and high-pressure steam, and this state is maintained for a predetermined time. At this time, the non-crosslinked rubber sheet 111′ flows and is press-fitted into the lower cog forming grooves 311a, and the cross-linking progresses about halfway and forms a composite with the reinforcing cloth 12, leading to the inner peripheral side as shown in FIG. 4C. A cylindrical lower cog composite 40 having a lower _cog CL formed therein is molded.

Next, steam is discharged from the vulcanization can, the sealing is broken, the first cylindrical mold 311 is taken out, and the first rubber sleeve 312 is removed to cool, and then, as shown in FIG. The outer peripheral portion of the molded lower cog composite 40 is cut with a knife to adjust the thickness.

Then, after demolding the lower cog composite 40 from the first cylindrical mold 311, it is fitted over the second cylindrical mold 321 as shown in 4E. At this time, the lower cog composite body 40 is provided so that the lower cog CL is fitted in the lower cog fitting groove _321a continuously provided on the outer circumference of the second cylindrical mold 321 in the circumferential direction.

Next, as shown in FIG. 4F, the uncrosslinked rubber sheet 113′ for forming the adhesive rubber layer 113 is wound on the lower cog composite 40 on the second cylindrical mold 321, and the core wire 13 is spirally wound thereon. An uncrosslinked rubber sheet 113′ for forming an adhesive rubber layer 113 and an uncrosslinked rubber sheet 112′ for forming an extension rubber layer 112 are wound in this order to form an uncrosslinked slab S′. do.

Next, as shown in FIG. 4G, the uncrosslinked slab S′ is covered with a second rubber sleeve 322, placed in a vulcanization can and sealed, and the vulcanization can is filled with high-temperature and high-pressure steam. , that state is maintained for a predetermined period of time. At this time, the main cross-linking of the lower cog complex 40 proceeds. At the same time, the uncrosslinked rubber sheet 113 ′ for forming the adhesive rubber layer 113 is also crosslinked and combined with the cord 13 . In addition, the uncrosslinked rubber sheet 112′ for forming the stretchable rubber layer 112 flows and is press-fitted into the upper cog forming groove 322a continuous in the circumferential direction of the inner circumference of the second rubber sleeve 322, and the cross-linking is performed. progresses. Then, as shown in FIG. 4H, the whole is integrated to form a cylindrical belt slab S.

<Width cutting/V side forming process>
Steam is discharged from the vulcanizing can, the sealing is broken, the second cylindrical mold 321 is taken out, the second rubber sleeve 322 is removed, and the belt slab S is removed from the second cylindrical mold 321 after cooling.

Then, as shown in FIG. 5A, after cutting the belt slab S into a predetermined width, as shown in FIG. Get Belt B.

Although the double cogged V-belt B is shown in the above embodiment, it is not particularly limited to this, and may be a single cogged V-belt having only lower cogs, or a low edge V-belt having no cogs. 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 may be used, and the same effects as those of the above-described embodiment can be obtained. Furthermore, 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 may be used, and high performance can be obtained. Specifically, in these cases, the crosslinked rubber composition X has nanofibers oriented in the belt width direction and has relatively high rigidity in the belt width direction, so warping in the belt width direction can be suppressed. In addition, since the belt has relatively low rigidity in the longitudinal direction, it can be bent with a small force and wound around the pulley, and as a result, stable belt running performance can be obtained over a long period of time.

(Crosslinked rubber composition and double cogged V belt)
Crosslinked rubber compositions and double cogged V-belts of Examples 1 to 4 and Comparative Examples 1 to 3 were prepared. The respective configurations are also shown in Tables 1 and 2.

<Example 1>
A rubber component EPDM (T7241 manufactured by JSR Co., ethylene content: 52% by mass, ENB content: 7.7% by mass) is added to a Banbury mixer, and polyethylene resin-PET nanofiber is added to 100 parts by mass of this rubber component. 3.6 parts by mass of the composite material (Nanofront, manufactured by Teijin Frontier Co., Ltd.) was added and kneaded at a temperature higher than the melting point of the polyethylene resin contained in the composite material. After that, with respect to 100 parts by mass of the rubber component, ISAF carbon black (Seist 6 manufactured by Tokai Carbon Co., Ltd., arithmetic mean particle diameter: 22 nm, nitrogen adsorption specific surface area: 119 m ² / g) 40 parts by mass, process oil (Thumper 2280 Sun Oil Co., Ltd.) 10 parts by mass, processing aid stearic acid (stearic acid S50, Shin Nippon Rika Co., Ltd.) 0.25 parts by mass, vulcanization accelerator zinc oxide (3 types of zinc oxide, Sakai Chemical Co., Ltd.) 5 parts by mass , co-crosslinking agent zinc dimethacrylate (Actor ZMA, manufactured by Kawaguchi Chemical Industry Co., Ltd.) 20 parts by mass, co-crosslinking agent amylphenol disulfide polymer (Sancellar AP manufactured by Sanshin Chemical Industry Co., Ltd.) 1 part by mass, and co-crosslinking agent 4 parts by mass of N,N'-m-phenylene bismaleimide (Balnok PM, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) was further added and kneaded.

Next, the kneaded mass of the uncrosslinked rubber composition is discharged from the Banbury mixer and cooled once, and then added to 100 parts by mass of the rubber component, polyparaphenylene terephthalamide short fibers of para-aramid short fibers ( Kevlar 119 manufactured by DuPont) 28 parts by mass, sulfur as a cross-linking agent (Seimi OT manufactured by Nippon Dry Distillation Co., Ltd.) 0.5 parts by mass and organic peroxide as a cross-linking agent (Peroximone F-40 manufactured by NOF Corporation, purity 40 mass %) and 7 parts by mass (2.8 parts by mass of the active ingredient) were put into the Banbury mixer again and kneaded.

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

Then, the obtained uncrosslinked rubber sheet was press-molded to prepare a sheet-like crosslinked rubber composition. Further, a double cogged V-belt having the same configuration as the above embodiment, in which a compressed rubber layer was formed using the obtained uncrosslinked rubber sheet, was produced. The sheet-shaped crosslinked rubber composition and the double cogged V-belt were referred to as Example 1.

Here, the composite material used above has a sea-island structure of a polyethylene resin sea and nanofiber islands of 1200 PET fibers.

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

The composite has an outer diameter of 30 μm and a length of 1 mm. Therefore, the fiber length l ₁ of the nanofibers of PET fibers is 1 mm. _The fiber diameter d1 is 700 nm. The fiber diameter d2 of polyparaphenylene terephthalamide short fibers, which are para _- aramid short fibers, is 12 μm. The fiber length l2 is ₃ mm.

The extension rubber layer and the adhesive rubber layer of the double cogged V-belt were formed from a crosslinked rubber composition containing EPDM as a rubber component. The cord was composed of a twisted yarn of PET fibers. The reinforcing fabric was composed of a woven fabric of PET fibers.

<Example 2>
A sheet-like 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.

<Example 3>
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. A sheet-like crosslinked rubber composition and a double-cogged V-belt were prepared in the same manner as in Example 3.

<Example 4>
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 also 1 part by mass with respect to 100 parts by mass of the rubber component. A sheet-like crosslinked rubber composition and a double-cogged V-belt were prepared in the same manner as in Example 4.

<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 Comparative example 1 was used.

<Comparative Example 2>
Sheet-shaped crosslinked rubber composition 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 the amylphenol disulfide polymer and sulfur were not used. and a double-cogged V-belt were produced and designated as Comparative Example 2.

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

(Test method)
<Elongation at break EB>
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-grain direction at 25° C. was measured according to JIS K6251:2017.

<Fresh storage elastic modulus E′>
The sheet-like crosslinked rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 3 were each measured for the freshly stored elastic modulus E' at 25°C by a tensile method in accordance with JIS K6394:2007. The measurement conditions were as follows: strain when a load 1.3 times the load at a strain of 1% was applied as average strain, strain amplitude of 0.1%, frequency of 10 Hz, and test temperature of 25°C.

<Belt running test>
6A and B show a belt running tester 50. FIG. The belt running tester 50 has a drive 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 capable of applying a constant load DW (dead weight) so as to generate a constant belt tension in the double cogged V-belt B. As shown in FIG.

For each of the double cogged V-belts of Examples 1 to 4 and Comparative Examples 1 to 3, first, as shown in FIG. The belt is wound around the drive pulley 51 and around the driven pulley 52 so that the winding diameter at the center position of the core wire is 263 mm. A low-speed layout was formed by this, and then the drive pulley 51 was rotated at 7500 rpm under an ambient temperature of 30° C. to start running the belt at a low speed. Then, the belt was run until the double cogged V-belt was cut, and the time from the start of belt running to cut was defined as the low speed belt life. The maximum belt running time was set to 200 hours.

Further, as shown in FIG. 6B, the double cogged V-belt B is wound around the drive pulley 51 so that the winding diameter at the core wire center position is 210 mm, and the winding diameter at the core wire center position is 210 mm. A high-speed layout is constructed by winding around the driven pulley 52 so as to have a length of 165 mm and applying a constant load DW of 2300 N to the driven pulley 52 to generate belt tension. 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 cut was taken as the high-speed belt life. The maximum belt running time was set to 50 hours.

(Test results)
Table 3 shows the test results. According to Table 3, according to Examples 1 to 4, excellent durability can be obtained in both low speed and high speed belt running. On the other hand, in Comparative Examples 1 to 3, excellent durability was not obtained in both low speed and high speed belt running.

INDUSTRIAL APPLICABILITY The present invention is useful in the technical field of power transmission belts.

B Double cogged V-belt (transmission belt)
C _L lower cog C _U upper cog M Composite material R Thermoplastic resin F Nanofiber S' Uncrosslinked slab S Belt slab 11 Belt body 111 Compressed rubber layers 111', 112', 113' Uncrosslinked rubber sheet 111a V side 112 Stretched Rubber layer 113 Adhesive rubber layer 12 Reinforcing cloth 13 Core wire 20 Transmission 21 Drive pulleys 211, 221 Fixed sheaves 212, 222 Movable sheave 22 Driven pulley 23 V groove 311 First cylindrical mold 311a Lower cog forming groove 312 First rubber sleeve 321 Second Cylindrical Mold 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 Tester 51 Driving Pulley 52 Driven Pulley

Claims (8)

A power transmission belt in which at least a portion of the belt body is formed of a crosslinked rubber composition,
The crosslinked rubber composition comprises 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 the 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 content of the carbon black and the zinc dimethacrylate A transmission belt having a sum of 35 parts by mass or more and 75 parts by mass or less. In the transmission belt according to claim 1,
The power transmission belt, wherein the content of the nanofiber in the uncrosslinked rubber composition is 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the rubber component. In the transmission belt according to claim 1 or 2,
The transmission belt, wherein the content of the zinc dimethacrylate in the uncrosslinked rubber composition is 0.5 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the rubber component. In the transmission belt according to any one of claims 1 to 3,
A power transmission belt in which the content of the zinc dimethacrylate in the uncrosslinked rubber composition is the same as the content of the carbon black, or less than the content of the carbon black. In the transmission belt according to any one of claims 1 to 4,
A power transmission belt, wherein the uncrosslinked rubber composition contains an amylphenol disulfide polymer. In the transmission belt according to any one of claims 1 to 5,
The power transmission belt, wherein the uncrosslinked rubber composition contains short fibers. In the transmission belt according to any one of claims 1 to 6,
A power transmission belt, wherein the power transmission belt is a V-belt or a V-ribbed belt. In the transmission belt according to any one of claims 1 to 6,
A power transmission belt, wherein the power transmission belt is a toothed belt or a flat belt.

Images