JP6809985B2 - Friction transmission belt - Google Patents

Description

The present invention relates to a friction transmission belt such as a V-belt or a V-ribbed belt in which a friction transmission surface is inclined in a V shape and power is transmitted via a frictional force generated between a pulley and a side surface of the belt.

The friction transmission belt transmits power through the frictional force generated between the pulley and the side surface of the belt. The larger the coefficient of friction between the pulley and the side surface of the belt, the larger the frictional force, which is advantageous in terms of power transmission. However, if the coefficient of friction becomes too high, the force required for the belt to come out of the pulley becomes large, and it becomes difficult for the belt to come out of the pulley. As a result, the belt is bent in the reverse direction near the outlet of the pulley, which causes heat generation and noise. In particular, in belts used for shifting in motorcycles, shifting is performed by moving the belt between pulleys in the pulley radial direction, and when the friction coefficient on the side surface of the belt becomes high, the belt moves in the pulley radial direction. A lot of transmission loss occurs in the belt, which also reduces fuel efficiency. Various means for reducing the coefficient of friction have been conventionally proposed for these problems, but since the lateral pressure resistance of the belt can be improved in addition to reducing the coefficient of friction, the compressed rubber layer The method of blending short fibers has been widely used.

However, while the short fibers lower the coefficient of friction and improve the lateral pressure resistance of the belt, they become the starting points of cracks generated in the rubber and lower the durability of the belt, so that they cannot be blended in a large amount.

According to Japanese Patent Application Laid-Open No. 7-31006 (Patent Document 1), a rubber power transmission belt having a V-shaped compression portion, in which short fibers are projected and embedded in the side wall surface of the V-type compression portion, and further, talc, A power transmission belt is disclosed in which a powdery viscosity inhibitor selected from calcium carbonate, clay, and silica is attached in a form of embedding the protrusions of the short fibers.

However, when powder is applied to the side surface of the belt, the coefficient of friction can be reduced at the initial stage of running, but the powder scatters with the passage of time, and the effect is lost at an early stage. Further, when the powder is excessively applied, the frictional force is lowered more than necessary, and the power transmission function may be impaired.

According to JP-A-2007-232205 (Patent Document 2), the friction transmission surface is 10 to 25 parts by weight of a plasticizer such as a petroleum-based plasticizer and carbon black, etc., with respect to 100 parts by weight of an ethylene / α-olefin elastomer. A friction transmission belt made of a rubber composition containing 60 to 110 parts by weight of the inorganic filler of the above is disclosed. This document describes that by adding a plasticizer to the rubber composition, the bleeding plasticizer can maintain an appropriate coefficient of friction.

However, when a plasticizer is added to the rubber composition, the effect of reducing the coefficient of friction is exhibited for a relatively long period of time, but the plasticizer still bleeds mainly from the vicinity of the belt surface. After a certain period of time, the bleeding of the plasticizer will decrease. In addition, the amount of bleeding of the plasticizer is greatly affected by the temperature conditions, and depending on the conditions, the expected amount does not bleed and the friction coefficient does not decrease so much, or conversely, excessive bleeding causes excessive friction. The coefficient decreases. In addition, it is necessary to add a relatively large amount of plasticizer in order to reduce the coefficient of friction, but when a large amount of plasticizer is added, the physical characteristics of the rubber deteriorate, and the lateral pressure resistance and durability of the belt Causes a decrease in.

Japanese Patent Application Laid-Open No. 2005-15769 (Patent Document 3) describes 10 to 50 parts by mass of short polyamide fibers and 10 to 100 parts by mass of a solid lubricant with respect to 100 parts by mass of raw rubber such as ethylene / α-olefin elastomer. A transmission belt with a compounded compression rubber layer is disclosed. This document describes that graphite, molybdenum disulfide, polytetrafluoroethylene (PTFE), or the like is used as the solid lubricant to reduce the coefficient of friction of the rubber composition.

However, when a solid lubricant is added to the rubber composition, although the effect of reducing the friction coefficient is exhibited for a long period of time, a large amount of solid lubricant is exhibited in order to exhibit a sufficient effect of reducing the friction coefficient. Need to be added. If the amount of the solid lubricant added is too large, the workability of the rubber will be reduced, the elongation of the rubber will be reduced and the bending fatigue resistance will be reduced, and the rubber will become the starting point of cracks and the durability will be reduced. ..

Jitsufuku No. 7-31006 (Claims for Utility Model Registration) JP-A-2007-232205 (Claims, paragraph [0046]) Japanese Unexamined Patent Publication No. 2005-15769 (Claims, paragraph [0024])

An object of the present invention is to provide a friction transmission belt capable of improving slidability without impairing wear resistance, lateral pressure resistance (rigidity) and durability.

Another object of the present invention is to provide a friction transmission belt capable of improving sound resistance and fuel efficiency without impairing durability even in a harsh situation in a high load environment such as a speed change belt.

As a result of diligent studies to achieve the above problems, the present inventor has formed the friction transmission surface of the compression rubber layer in the friction transmission belt with a vulcanized product of a rubber composition containing a rubber component and graphenes, thereby causing abrasion resistance. The present invention has been completed by finding that slidability can be improved without impairing properties, lateral pressure resistance and durability.

That is, the friction transmission belt of the present invention is a friction transmission belt provided with a compression rubber layer having a friction transmission surface at least partially in contact with the pulley, and the friction transmission surface of the compression rubber layer is a rubber component and It is made of a vulcanized rubber composition containing graphenes. The ratio of the graphenes is about 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The average particle size of the graphenes is about 0.1 to 3 μm. The compressed rubber layer may further contain short fibers. The short fibers may be oriented in the belt width direction. The ratio of the short fibers may be 30 parts by mass or less with respect to 100 parts by mass of the rubber component. The ratio of the graphenes is 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component, and the compressed rubber layer may further contain a solid lubricant and / or a friction modifier. The ratio of the graphenes is about 1 to 50 parts by mass with respect to 100 parts by mass in total of the solid lubricant and the friction modifier. The rubber component may be chloroprene rubber. The friction transmission belt of the present invention may be a low-edge cogged V-belt.

In the present invention, since the friction transmission surface of the compression rubber layer in the friction transmission belt is formed of a vulcanized product of a rubber composition containing a rubber component and graphenes, the abrasion resistance, lateral pressure resistance and durability are impaired. It is possible to improve the slidability. In particular, by reducing the friction coefficient of the friction transmission surface, heat generation and noise can be reduced, and transmission loss can be reduced. Therefore, even in a harsh situation in a high load environment such as a speed change belt, sound resistance and fuel saving can be improved without impairing durability.

FIG. 1 is a schematic perspective view showing an example of a friction transmission belt of the present invention. FIG. 2 is a schematic cross-sectional view of the friction transmission belt of FIG. 1 cut in the longitudinal direction of the belt. FIG. 3 is a schematic view for explaining a durability running test of the friction transmission belt in the embodiment.

[Structure of friction transmission belt]
As the friction transmission belt of the present invention, it is sufficient that the friction transmission surface of the compressed rubber layer contains a rubber component and graphenes, and a conventional friction transmission belt can be used. Examples of the friction transmission belt of the present invention include V-belts [wrapped V-belts, low-edge V-belts, low-edge cogged V-belts (low-edge cogged V-belts having cogs formed on the inner peripheral side of the low-edge belts, low-edge belts). Low-edge double-cogged V-belts with cogs formed on both the peripheral side and the outer peripheral side)], V-ribbed belts, flat belts, and the like can be exemplified. Among these friction transmission belts, a V-belt or a V-ribbed belt in which the friction transmission surface is formed to be inclined in a V shape (at a V angle) is preferable from the viewpoint of receiving a large amount of lateral pressure from the pulley, and lateral pressure resistance and lateral pressure resistance and A low-edge cogged V-belt is particularly preferable because it is used in a belt-type continuously variable transmission that requires a high degree of both durability and fuel efficiency.

FIG. 1 is a schematic perspective view showing an example of a friction transmission belt (low-edge cogged V-belt) of the present invention, and FIG. 2 is a schematic cross-sectional view of the friction transmission belt of FIG. 1 cut in the longitudinal direction of the belt.

In this example, the friction transmission belt 1 has a plurality of cog portions 1a formed on the inner peripheral surface of the belt body at predetermined intervals along the longitudinal direction of the belt, and the cog portions 1a of the cog portions 1a. The cross-sectional shape in the longitudinal direction (A direction in the figure) is approximately semicircular (curved or wavy), and the cross-sectional shape in the direction orthogonal to the longitudinal direction (width direction or B direction in the figure) is a table. The shape. That is, each cog portion 1a protrudes in a substantially semicircular shape in the cross section from the cog bottom portion 1b in the A direction in the belt thickness direction. The friction transmission belt 1 has a laminated structure, and the reinforcing cloth 2, the stretch rubber layer 3, the adhesive rubber layer 4, and the compression are applied from the outer peripheral side of the belt to the inner peripheral side (the side where the cog portion 1a is formed). The rubber layer 5 and the reinforcing cloth 6 are sequentially laminated. The cross-sectional shape in the belt width direction is a trapezoidal shape in which the belt width decreases from the outer peripheral side to the inner peripheral side of the belt. Further, a core body 4a is embedded in the adhesive rubber layer 4, and the cog portion 1a is formed in the compressed rubber layer 5 by a molding die with a cog.

[Compressed rubber layer]
In the present invention, since the friction transmission surface of the compressed rubber layer is formed of a vulcanized product of a rubber composition containing a rubber component and graphenes, graphenes are present on at least a part of the friction transmission surface of the compression rubber layer. , The friction coefficient of the friction transmission surface can be reduced (sliding property is improved). The compressed rubber layer may have a friction transmission surface formed of the rubber composition. For example, on the friction transmission surface, a surface layer portion formed of a rubber composition containing graphenes is formed, and another portion (inner layer) is formed. Part) may be a compressed rubber layer containing no graphenes, but from the viewpoint of productivity and the like, a compressed rubber layer in which the entire compressed rubber layer is formed of a rubber composition containing graphenes is preferable.

(Graphenes)
Graphenes include a graphene sheet, which is a single sheet usually called "graphene", and a graphene film (multilayer graphene), which is a laminate of the graphene sheets.

The graphene sheet is a material constituting graphite, and is a sheet of sp ^2- bonded carbon atoms (single-layer sheet) having a thickness of 1 atom. The structure has a honeycomb-like hexagonal lattice structure (honeycomb structure) formed from carbon atoms and their bonds.

The graphene film is obtained by peeling graphite, is a thin-walled laminate as compared with graphite, and has a crystal structure. The number of laminated graphene films is, for example, about 2 to 20, preferably about 3 to 10.

The aspect ratio (average diameter / average thickness of the plate surface) of the graphene film may be 20 or more, for example, 20 to 100,000, preferably 50 to 30,000, and more preferably about 100 to 10,000. The average thickness of the graphene film may be, for example, about 1 to 10 nm, preferably about 1.5 to 5 nm.

Graphenes may contain graphene oxide, or may be formed only of graphene oxide.

The shape of graphenes is not particularly limited, and examples thereof include sheet-like, granular (powder-like or indefinite-shaped), and a combination of sheet-like and granular. Of these shapes, granules are preferable because they are easy to handle and can be easily dispersed uniformly in the resin component.

When the graphenes are granular, the average particle size of the graphenes may be 50 μm or less, for example 0.01 to 50 μm, preferably 0.03 to 10 μm, more preferably 0.05 to 5 μm (particularly 0. It is about 1 to 3 μm). If the average particle size is too small, it may scatter when blended with the rubber component and the handleability may be deteriorated. If the average particle size is too large, agglomerates are likely to be formed in the rubber component and it is difficult to disperse them uniformly. There is a risk of becoming.

In the present specification and claims, the average particle size of graphenes is observed with a scanning electron microscope (“JSM-5900LV” manufactured by JEOL Ltd.) at a magnification of 5000 times, and is randomly 20. It can be determined by a method of measuring the particle size of individual particles and averaging them.

Graphenes can be produced by a conventional method, and may be produced, for example, by the methods described in Japanese Patent No. 5688669, Japanese Patent No. 5697067, Japanese Patent Application Laid-Open No. 2015-501873, and WO2013 / 146213.

The ratio of graphenes can be selected from the range of about 0.1 to 15 parts by mass (for example, 0.1 to 10 parts by mass) with respect to 100 parts by mass of the rubber component, for example, 0.2 to 10 parts by mass, preferably 0. .3 to 8 parts by mass, more preferably about 0.5 to 5 parts by mass (particularly 0.8 to 3 parts by mass).

When the rubber composition contains short fibers, the ratio of graphenes is, for example, 0.5 to 100 parts by mass, preferably 1 to 50 parts by mass, and more preferably 3 to 40 parts by mass with respect to 100 parts by mass of the short fibers. It is about (particularly 5 to 30 parts by mass). When the rubber composition contains a conventional solid lubricant and / or friction modifier, the proportion of the graphenes is preferably 1 to 50 parts by mass, for example, with respect to 100 parts by mass of the total of the solid lubricant and the friction modifier. Is about 1.5 to 30 parts by mass, more preferably about 2 to 20 parts by mass (particularly about 3 to 15 parts by mass).

In the ratio of these graphenes, if the ratio of graphenes is too small, the effect of reducing the friction coefficient may be reduced, and if it is too large, the friction coefficient becomes too low and the belt slips, resulting in fuel saving. In addition to the risk of deterioration, the durability may also be reduced due to heat generated by slipping. The ratio of these graphenes is formed by a surface layer portion and other portions (inner layer portions) formed of a rubber composition containing graphenes and rubber components formed on the friction transmission surface of the compressed rubber layer. If so, it is the ratio in the rubber composition forming the surface layer portion.

(Short fiber)
In the present invention, the rubber composition forming the friction transmission surface does not have to contain short fibers, but it is preferable that the rubber composition further contains short fibers in addition to the graphenes. The lateral pressure resistance of the friction transmission belt can be ensured by blending short fibers with the rubber composition forming the compressed rubber layer that receives a large amount of lateral pressure and frictional force from the pulley, and preferably by orienting the short fibers in the belt width direction. .. On the other hand, from the viewpoint of belt durability, it is preferable that the ratio of short fibers is the minimum necessary to ensure lateral pressure resistance. In the present invention, the proportion of short fibers can be adjusted to the minimum necessary due to the presence of graphenes, so that the bending rigidity of the belt can be kept small while maintaining the lateral pressure resistance. Therefore, both the coefficient of friction (improvement of slidability) and flexural rigidity (improvement of flexibility) can be reduced, transmission loss is small, and fuel efficiency can be ensured. That is, when short fibers and graphenes are used in combination, lateral pressure resistance and fuel saving (both flexibility and slidability) can be improved.

Examples of short fibers include polyolefin fibers (polyethylene fiber, polypropylene fiber, etc.), polyamide fibers (polyamide 6 fiber, polyamide 66 fiber, polyamide 46 fiber, aramid fiber, etc.), polyalkylene allylate fiber [polyethylene terephthalate (PET)). Fibers, poly C _2-4 alkylene C _6-14 allylate fibers such as polyethylene naphthalate (PEN) fibers], vinylon fibers, polyvinyl alcohol fibers, synthetic fibers such as polyparaphenylene benzobisoxazole (PBO) fibers; Natural fibers such as cotton, hemp and wool; inorganic fibers such as carbon fibers are widely used. These short fibers can be used alone or in combination of two or more. Of these short fibers, synthetic fibers and natural fibers, especially synthetic fibers (polyamide fibers, polyalkylene allylate fibers, etc.), among others, are rigid, have high strength and modulus, and easily protrude on the surface of the compressed rubber layer, so at least Short fibers containing aramid fibers are preferred. Aramid short fibers also have high wear resistance. Aramid fibers are commercially available, for example, under the trade names "Cornex", "Nomex", "Kevlar", "Technora", "Twaron" and the like.

The short fibers are oriented in the belt width direction and embedded in the compressed rubber layer in order to suppress the compressive deformation of the belt due to the pressure from the pulley. Further, by projecting the short fibers from the surface of the compressed rubber layer, the friction coefficient of the surface can be lowered to suppress noise (pronunciation), and wear due to rubbing against the pulley can be reduced. The average length of the short fibers may be, for example, 1 to 20 mm, preferably 1.2 to 15 mm (for example, 1.5 to 10 mm), and more preferably 2 to 5 mm (particularly 2.5 to 4 mm). If the average length of the short fibers is too short, the mechanical properties in the columnar direction (for example, modulus) may not be sufficiently enhanced, and if it is too long, the short fibers in the rubber composition may be poorly dispersed. As a result, the rubber may crack and the belt may be damaged prematurely.

The average protruding height of the short fibers on the entire friction transmission surface may be 50 μm or more, for example, 50 to 200 μm, preferably 60 to 180 μm, and more preferably 70 to 160 μm (particularly 80 to 150 μm). If the average protrusion height is too small, the friction coefficient of the surface may not be sufficiently reduced, and conversely, if it is too large, breakage or dropout is likely to occur. For the average protrusion height, for example, a cross section cut in the belt width direction is magnified and observed with an electron microscope or the like, and a plurality of short fibers (protrusion height) protruding from the side surface of the belt are formed (for example, 10 to 1000 fibers, preferably 10 to 1000). 30 to 500 lines, more preferably 50 to 200 lines, particularly about 100 lines), and these can be averaged and calculated.

The average fiber diameter of the short fibers is, for example, 1 to 100 μm, preferably 3 to 50 μm, and more preferably 5 to 30 μm (particularly 10 to 20 μm). If the average fiber diameter is too large, the mechanical properties of the compressed rubber layer may deteriorate, and if it is too small, the friction coefficient of the surface may not be sufficiently reduced.

The shape of the short fibers in the protruding portion is not particularly limited, and is a shape protruding substantially vertically from the side surface, a shape curled in one direction (for example, the polishing direction), a shape in which the tip is fibrillated, and melted by heat during polishing. It may have a shape such as a flowering shape. Further, the shape may be described in JP-A-7-98044 and JP-A-7-151191.

In the present invention, the proportion of short fibers can be suppressed to a small amount by combining with graphenes existing on the friction transmission surface, so that the bending rigidity of the belt can be reduced and the transmission efficiency of the belt can be improved. The ratio of the short fibers may be 50 parts by mass or less (for example, 40 parts by mass or less, preferably 30 parts by mass or less) with respect to 100 parts by mass of the rubber component, for example, 10 to 25 parts by mass, preferably 12 to 23 parts by mass. It may be about 15 to 20 parts by mass, more preferably about 15 to 20 parts by mass, and for example, about 10 to 20 parts by mass (particularly about 12 to 18 parts by mass). If the proportion of short fibers is too small, the mechanical properties of the compressed rubber layer may deteriorate. On the other hand, if the amount is too large, in addition to the decrease in transmission efficiency, the dispersibility in the rubber composition of the short fibers is reduced, resulting in poor dispersion, and there is a risk that cracks will occur in the compressed rubber layer at an early stage starting from that location. There is also. In applications where durability is important, the proportion of short fibers may be 20 parts by mass or less (for example, 0 to 20 parts by mass) with respect to 100 parts by mass of the rubber component, for example, 15 parts by mass or less (for example). For example, 0 to 10 parts by mass), preferably 5 parts by mass or less (for example, 0 to 3 parts by mass), more preferably 1 part by mass or less (0 to 0.5 parts by mass), which is substantially short. It does not have to contain fibers.

From the viewpoint of dispersibility and adhesiveness of the short fibers in the rubber composition, it is preferable that at least the short fibers are adhesively treated (or surface treated). It is not necessary that all the short fibers are bonded, and the bonded short fibers and the non-bonded short fibers (untreated short fibers) may be mixed or used in combination.

In the adhesion treatment of short fibers, various adhesion treatments, for example, a treatment liquid containing an initial condensate of phenols and formalin (such as a prepolymer of a novolak or a resole-type phenol resin), a treatment liquid containing a rubber component (or latex), etc. , Treatment liquid containing the initial condensate and rubber component (latex), silane coupling agent, epoxy compound (epoxy resin, etc.), treatment liquid containing reactive compound (adhesive compound) such as isocyanate compound, etc. be able to. In a preferred adhesion treatment, the short fibers are treated with a treatment solution containing the initial condensate and a rubber component (latex), particularly at least a resorcin-formalin-latex (RFL) solution. Such treatment solutions may be used in combination, for example, the short fibers are preliminarily used with a conventional adhesive component, for example, a reactive compound (adhesive compound) such as an epoxy compound (epoxy resin or the like) or an isocyanate compound. After the treatment, it may be treated with an RFL solution.

When treated with such a treatment liquid, particularly an RFL liquid, the short fibers and the rubber component can be strongly adhered to each other. The RFL solution is a mixture of an initial condensate of resorcin and formaldehyde and a rubber latex. The molar ratio of resorcin to formaldehyde is within the range in which the adhesiveness between the rubber component and the short fibers can be improved, for example, the former / the latter = 1 / 0.5 to 1/3, preferably 1 / 0.6 to 1/2. It can be set to about 5.5, more preferably about 1 / 0.7 to 1 / 1.5, even if it is about 1 / 0.5 to 1/1 (for example, 1 / 0.6 to 1 / 0.8). Good. The type of latex is not particularly limited, and can be appropriately selected from the rubber components described later according to the type of rubber component to be adhered. For example, when the rubber component to be bonded is mainly chloroprene rubber, the latex is a diene rubber (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene-butadiene rubber (SBR), styrene-butadiene-vinyl). It may be a pyridine ternary copolymer, acrylonitrile-butadiene rubber (nitrile rubber), hydride nitrile rubber, etc.), ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, or the like. These latexes may be used alone or in combination of two or more. Preferred latexes are diene rubber (styrene-butadiene-vinylpyridine ternary copolymer, chloroprene rubber, butadiene rubber, etc.) and chlorosulfonated polyethylene rubber, and styrene-butadiene-vinylpyridine is used to further improve the adhesiveness. A ternary copolymer is preferable. When the short fibers are bonded with a treatment liquid (RFL liquid or the like) containing at least a styrene-butadiene-vinylpyridine ternary copolymer, the adhesiveness between the rubber composition (chloroprene rubber composition or the like) and the short fibers can be improved.

The ratio of the initial condensate of resorcin and formalin may be about 10 to 100 parts by mass (for example, 12 to 50 parts by mass, preferably 15 to 30 parts by mass) with respect to 100 parts by mass of the rubber component of the latex. The total solid content concentration of the RFL solution can be adjusted in the range of 5 to 40% by mass.

The adhesion ratio of the adhesive component (solid content) to the short fibers is, for example, 1 to 25% by mass, preferably 3 to 20% by mass, more preferably 5 to 15% by mass, and 3 to 10% by mass (particularly 4 to 8%). It may be about mass%). If the adhesive component is too low, the dispersibility of the short fibers in the rubber composition and the adhesiveness between the short fibers and the rubber composition are insufficient, and conversely, if the adhesive component is too large, the adhesive components are fiber filaments. Is firmly fixed, and there is a risk that the dispersibility will decrease.

The method for preparing the bonded short fibers is not particularly limited. For example, a method of impregnating the long fibers of the multifilament with the bonding liquid, drying the fibers and then cutting them to a predetermined length, or a method of cutting the untreated short fibers into the bonding liquid. A method can be used in which the adhesive is immersed in the fiber for a predetermined time, then the excess adhesive treatment liquid is removed by a method such as centrifugation, and then the adhesive is dried.

(Rubber component)
Examples of the rubber component include known vulverable or crosslinkable rubber components and / or elastomers, for example, diene rubber [for example, natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber (CR), styrene-butadiene rubber (SBR)). , Vinyl pyridine-styrene-butadiene copolymer rubber, acrylonitrile-butadiene rubber (nitrile rubber); the diene rubber such as hydride nitrile rubber (including a mixed polymer of hydride nitrile rubber and unsaturated carboxylic acid metal salt). , Etc.], olefin rubber [for example, ethylene-α-olefin rubber (ethylene-α-olefin elastomer), polyoctenylene rubber, ethylene-vinyl acetate copolymer rubber, chlorosulfonated polyethylene rubber, alkyl Chlorosulfonated polyethylene rubber, etc.], epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluorine rubber, etc. can be exemplified. These rubber components can be used alone or in combination of two or more.

Among these rubber components, ethylene-α-olefin elastomer (ethylene-propylene copolymer (EPM), ethylene-propylene-diene ternary copolymer (ethylene-propylene-diene ternary copolymer)) because the vulcanizing agent and the vulcanization accelerator are easily diffused. Ethylene-α-olefin rubber such as EPDM) and chloroprene rubber are widely used, and especially when used in a high load environment such as a speed change belt, mechanical strength, weather resistance, heat resistance, cold resistance, oil resistance, adhesiveness, etc. Chloroprene rubber and EPDM are preferable from the viewpoint of excellent balance. Further, chloroprene rubber is particularly preferable because it is excellent in wear resistance in addition to the above-mentioned characteristics. The chloroprene rubber may be a sulfur-modified type or a non-sulfur-modified type.

When the rubber component contains chloroprene rubber, the proportion of chloroprene rubber in the rubber component may be about 50% by mass or more (particularly 80 to 100% by mass), and 100% by mass (only chloroprene rubber) is particularly preferable.

(Solid lubricant and / or friction modifier)
The rubber composition may further comprise a conventional solid lubricant and / or friction modifier. In the present invention, by combining graphenes with a conventional solid lubricant and / or friction modifier, the friction coefficient of the friction transmission surface can be reduced without lowering the durability of the belt.

Examples of conventional solid lubricants include graphite, fluororesin (polytetrafluoroethylene, etc.), molybdenum disulfide, ultra-high molecular weight polyethylene, and the like. These solid lubricants can be used alone or in combination of two or more. As the friction modifier, inorganic powders and granules such as calcium carbonate, calcium phosphate, potassium titanate, aluminum borate, alumina, silica, mica, talc (hydrous magnesium silicate), iron powder, titanium oxide, pyrophyllite ( Rouseki clay) and the like. These friction modifiers can be used alone or in combination of two or more.

Of these, solid lubricants such as graphite, fluororesin, and ultra-high molecular weight polyethylene are preferable.

The total ratio of the solid lubricant and the friction modifier may be 50 parts by mass or less with respect to 100 parts by mass of the rubber component, for example, 1 to 50 parts by mass, preferably 3 to 40 parts by mass, and more preferably 5 to 5 parts by mass. It is about 30 parts by mass (particularly 10 to 20 parts by mass). If the ratio of the solid lubricant and the friction modifier is too large, the belt durability may decrease.

(Additive)
The rubber composition contains, if necessary, a vulcanizing agent or a cross-linking agent (or a cross-linking agent system), a co-cross-linking agent, a vulcanization aid, a vulcanization accelerator, a vulcanization retarder, and a metal oxide (for example, oxidation). Zinc, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, etc.), enhancer (carbon black, etc.), filler, softener (oils such as paraffin oil, naphthenic oil, etc.), processing agent or processing Auxiliary agents (fatty acids such as stearic acid, metal fatty acid salts such as metal stearic acid, fatty acid amides such as stearic acid amide, wax, paraffin, etc.), antiaging agents (antioxidants, heat antiaging agents, bending crack prevention) Agents, ozone deterioration inhibitors, etc.), colorants, tackifiers, plasticizers, lubricants, coupling agents (silane coupling agents, etc.), stabilizers (ultraviolet absorbers, heat stabilizers, etc.), flame retardants, antistatic agents It may contain an agent or the like. The metal oxide may act as a cross-linking agent.

As the vulcanizing agent or the cross-linking agent, conventional components can be used depending on the type of rubber component. For example, the metal oxide (magnesium oxide, zinc oxide, etc.) and the organic peroxide (diacyl peroxide, peroxy ester) can be used. , Dialkyl peroxide, etc.), sulfur-based vulcanizer, etc. can be exemplified. Examples of the sulfur-based sulfurizing agent include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and sulfur chloride (sulfur monochloride, sulfur dichloride, etc.). These cross-linking agents or vulcanizing agents may be used alone or in combination of two or more. When the rubber component is chloroprene rubber, a metal oxide (magnesium oxide, zinc oxide, etc.) may be used as a vulcanizing agent or a cross-linking agent. The metal oxide may be used in combination with another vulcanizing agent (sulfur-based vulcanizing agent, etc.), and the metal oxide and / or the sulfur-based vulcanizing agent may be used alone or in combination with a vulcanization accelerator. You may use it.

The ratio of the vulcanizing agent can be selected from the range of about 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component, depending on the type of the vulcanizing agent and the rubber component. For example, the ratio of the organic peroxide as a sulfide is about 1 to 8 parts by mass, preferably 1.5 to 5 parts by mass, and more preferably about 2 to 4.5 parts by mass with respect to 100 parts by mass of the rubber component. The ratio of the metal oxide can be selected from the above range of 1 to 20 parts by mass, preferably 3 to 17 parts by mass, and more preferably 5 to 15 parts by mass (particularly 7 to 13 parts by mass) with respect to 100 parts by mass of the rubber component. ) Can be selected from the range.

Examples of the co-crosslinking agent (cross-linking aid or co-sulfurizing agent co-agent) include known cross-linking aids such as polyfunctional (iso) cyanurate [for example, triallyl isocyanurate (TAIC) and triallyl cyanurate (eg, triallyl isocyanurate (TAIC)). TAC), etc.], polydiene (eg, 1,2-polybutadiene, etc.), metal salts of unsaturated carboxylic acids [eg, zinc (meth) acrylate, magnesium (meth) acrylate, etc.], oximes (eg, quinonedi). Oxym, etc.), guanidines (eg, diphenylguanidine, dio-tolylguanidine, etc.), polyfunctional (meth) acrylates [eg, ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, trimethyl propantri (eg, trimethylol propantri) Meta) acrylates, etc.], bismaleimides (aliphatic bismaleimides such as N, N'-1,2-ethylene dimaleimide, 1,6'-bismaleimide- (2,2,4-trimethyl) cyclohexane, etc .; Arene bismaleimide or aromatic bismaleimide, such as N, N'-m-phenylenedimaleimide, 4-methyl-1,3-phenylenedimaleimide, 4,4'-diphenylmethanedimaleimide, 2,2-bis [4] -(4-Maleimide phenoxy) phenyl] propane, 4,4'-diphenyl ether dimaleimide, 4,4'-diphenylsulphon dimaleimide, 1,3-bis (3-maleimide phenoxy) benzene, etc.) and the like. These cross-linking aids can be used alone or in combination of two or more. Among these cross-linking aids, bismaleimides (alene bismaleimide such as N, N'-m-phenylenedimaleimide or aromatic bismaleimide) are preferable. By adding bismaleimides, the degree of cross-linking can be increased and adhesive wear can be prevented.

The ratio of the co-crosslinking agent (crosslinking aid) can be selected from the range of about 0.01 to 10 parts by mass with respect to 100 parts by mass of the rubber component in terms of solid content, for example, 0.1 to 10 parts by mass (for example, 0). .3 to 8 parts by mass), preferably about 0.5 to 6 parts by mass (particularly 1 to 5 parts by mass).

Examples of the sulfide accelerator include thiuram-based accelerators [for example, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD). ), Dipentamethylene thiuram tetrasulfide (DPTT), N, N'-dimethyl-N, N'-diphenylthiuram disulfide, etc.], thiazol-based accelerators [eg, 2-mercaptobenzothiazol, 2 -Zinc salt of mercaptobenzothiazol, 2-mercaptothiazolin, dibenzothiazil disulfide, 2- (4'-morpholinodithio) benzothiazole, etc.], sulfenamide-based accelerator [for example, N-cyclohexyl-2 -Benzothiazyl sulphenamide (CBS), N, N'-dicyclohexyl-2-benzothiazyl sulphenamide, etc.], urea-based or thiourea-based accelerators (eg, ethylene thiourea, etc.), dithiocarbamates, xanthogenic acid Examples include salts. These vulcanization accelerators can be used alone or in combination of two or more. Among these vulcanization accelerators, TMTD, DPTT, CBS and the like are widely used.

The ratio of the vulcanization accelerator is, for example, 0.1 to 15 parts by mass, preferably 0.3 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component in terms of solid content. It may be about a part.

The ratio of the enhancer (carbon black, silica, etc.) is about 10 to 100 parts by mass (preferably 20 to 80 parts by mass, more preferably 30 to 70 parts by mass) with respect to 100 parts by mass of the total amount of the rubber component. May be good. The ratio of the softener (oils such as naphthenic oil) is, for example, 1 to 30 parts by mass, preferably 3 to 20 parts by mass (for example, 5 to 10 parts by mass) with respect to 100 parts by mass of the total amount of rubber components. It may be about. The ratio of the processing agent or processing aid (such as stearic acid) is 10 parts by mass or less (for example, 0 to 10 parts by mass), preferably 0.1 to 5 parts by mass, with respect to 100 parts by mass of the rubber component. More preferably, it may be about 0.3 to 3 parts by mass (particularly 0.5 to 2 parts by mass). Further, the ratio of the anti-aging agent is, for example, 0.5 to 15 parts by mass, preferably 1 to 10 parts by mass, and more preferably 2.5 to 7.5 parts by mass with respect to 100 parts by mass of the total amount of the rubber component. In particular, it may be about 3 to 7 parts by mass).

[Stretch rubber layer]
The stretched rubber layer may be formed of a vulcanized rubber composition containing the rubber component exemplified by the compressed rubber layer, and may contain graphenes and short fibers as in the compressed rubber layer. Further, the stretched rubber layer may be a layer formed of the same vulcanized rubber composition as the compressed rubber layer except for graphenes.

[Adhesive rubber layer]
The rubber composition for forming the adhesive rubber layer is a rubber component (chloroprene rubber, etc.), a vulcanizing agent, or a cross-linking agent (metal oxidation such as magnesium oxide, zinc oxide, etc.), similarly to the vulcanized rubber composition of the compressed rubber layer. Products, sulfur-based vulcanizing agents such as sulfur), co-crosslinking agents or cross-linking aids (maleimide-based cross-linking agents such as N, N'-m-phenylenedi maleimide), vulcanization accelerators (TMTD, DPTT, CBS) , Etc.), enhancers (carbon black, silica, etc.), softeners (oils such as naphthenic oils), processing agents or processing aids (stearic acid, metal stearate, wax, paraffin, etc.), antiaging agents, Adhesive improver [Resolsin-vulcanization cocondensate, amino resin (condensate of nitrogen-containing cyclic compound and formaldehyde, for example, hexamethylol melamine, hexaalkoxymethyl melamine (hexamethoxymethyl melamine, hexabutoxymethyl melamine, etc.), etc.) Melamine resin, urea resin such as methylol urea, benzoguanamine resin such as methylolbenzoguanamine resin, etc.), their cocondensates (resorcin-melamine-formaldehyde cocondensate, etc.)], fillers (clay, calcium carbonate, talc, mica, etc.) Etc.), colorants, tackifiers, plasticizers, coupling agents (silane coupling agents, etc.), stabilizers (ultraviolet absorbers, heat stabilizers, etc.), flame retardants, antistatic agents, etc. may be included. .. In the adhesiveness improving agent, the resorcin-formaldehyde cocondensate and the amino resin may be an initial condensate (prepolymer) of a nitrogen-containing cyclic compound such as resorcin and / or melamine and formaldehyde.

In this rubber composition, as the rubber component, rubber of the same type (diene type rubber or the like) or the same type (chloroprene rubber or the like) as the rubber component of the rubber composition of the compressed rubber layer is often used. The amounts of the vulcanizing agent or cross-linking agent, co-cross-linking agent or cross-linking aid, vulcanization accelerator, enhancer, softener and anti-aging agent are in the same range as the rubber composition of the compressed rubber layer. You can choose from. Further, in the rubber composition of the adhesive rubber layer, the ratio of the processing agent or processing aid (stearic acid or the like) is 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component. It may be about 1 to 3 parts by mass, more preferably 1 to 3 parts by mass. The ratio of the adhesiveness improving agent (resorcin-formaldehyde copolymer, hexamethoxymethylmelamine, etc.) is 0.1 to 20 parts by mass, preferably 1 to 10 parts by mass, more preferably 1 part by mass, based on 100 parts by mass of the rubber component. May be about 2 to 8 parts by mass. Further, graphenes may or may not be contained in the same proportion as the rubber composition of the compressed rubber layer.

[Core body]
The core body is not particularly limited, but usually, core wires (twisted cords) arranged at predetermined intervals in the belt width direction can be used. The core wires are arranged so as to extend in the longitudinal direction of the belt, and are usually arranged so as to extend in parallel at a predetermined pitch parallel to the longitudinal direction of the belt. The core wire may be at least partially in contact with the adhesive rubber layer, and the adhesive rubber layer has a form in which the core wire is embedded, a form in which the core wire is embedded between the adhesive rubber layer and the stretch rubber layer, and an adhesive rubber. It may be in any form in which the core wire is embedded between the layer and the compressed rubber layer. Of these, a form in which the adhesive rubber layer embeds the core wire is preferable from the viewpoint of improving durability.

Examples of the fibers constituting the core wire include fibers similar to the short fibers. Among the fibers, from the viewpoint of high modulus, polyester fibers ethylene terephthalate, a C _2-4 alkylene C _6-14 arylate such as ethylene-2,6-naphthalate as a main constituent unit (polyalkylene arylate-series fiber), a polyamide Synthetic fibers such as fibers (aramid fibers and the like), inorganic fibers such as carbon fibers and the like are widely used, and polyester fibers (polyester terephthalate fiber, polyethylene naphthalate fiber) and polyamide fiber are preferable. The fiber may be a multifilament yarn. The fineness of the multifilament yarn may be, for example, about 2000 to 10000 denier (particularly 4000 to 8000 denier). The multifilament yarn may be, for example, 100 to 5,000 yarns, preferably 500 to 4,000 yarns, and more preferably 1,000 to 3,000 yarns.

As the core wire, a twisted cord using a multifilament yarn (for example, various twists, single twist, rung twist, etc.) can be usually used. The average wire diameter of the core wire (fiber diameter of the twisted cord) may be, for example, 0.5 to 3 mm, preferably 0.6 to 2 mm, and more preferably about 0.7 to 1.5 mm. Good.

The core wire may be adhered (or surface-treated) in the same manner as the short fiber in order to improve the adhesiveness with the rubber component. Like the short fibers, the core wire is preferably bonded with at least an RFL solution.

[Reinforcing cloth]
When a reinforcing cloth is used in the friction transmission belt, it is not limited to the form in which the reinforcing cloth is laminated on the surface of the compressed rubber layer. For example, the reinforcing cloth is applied to the surface of the stretch rubber layer (the surface opposite to the adhesive rubber layer). It may be laminated, or may be in the form of embedding a reinforcing layer in the compressed rubber layer and / or the stretched rubber layer (for example, the form described in Japanese Patent Application Laid-Open No. 2010-230146). The reinforcing cloth can be formed of, for example, a woven cloth, a wide-angle sail cloth, a knitted cloth, a cloth material such as a non-woven fabric (preferably a woven cloth), and if necessary, the adhesive treatment, for example, a treatment with an RFL liquid (immersion treatment). Etc.), friction by rubbing the adhesive rubber into the cloth material, or laminating the adhesive rubber and the cloth material, and then laminating on the surface of the compressed rubber layer and / or the stretched rubber layer.

[Manufacturing method of friction transmission belt]
The method for manufacturing the friction transmission belt of the present invention is not particularly limited, and a conventional method can be used for the laminating step of each layer (method for manufacturing the belt sleeve).

For example, in the case of Cogged V-belt, a laminated body composed of a reinforcing cloth (lower cloth) and a sheet for a compressed rubber layer (unvulcanized rubber) is alternately arranged with teeth and grooves with the reinforcing cloth facing down. A cog pad (not completely vulcanized, semi-vulcanized) in which the cog part is molded by pressing and pressing at a temperature of about 60 to 100 ° C (especially 70 to 80 ° C) by installing it in a flat mold with a cog. After making a certain pad), both ends of the cog pad may be cut vertically from the top of the cog ridge. Further, a cylindrical mold is covered with an inner mother mold in which teeth and grooves are alternately arranged, and the cog pad is wound by engaging the teeth and the groove and jointed at the top of the cog ridge, and this winding is performed. After laminating the first adhesive rubber layer sheet (lower adhesive rubber: unvulcanized rubber) on the cog pad, the core body is spun spirally, and the second adhesive rubber layer sheet (upper adhesive) is spun on this. Rubber: The same as the adhesive rubber layer sheet), the stretch rubber layer sheet (unvulcanized rubber), and the reinforcing cloth (upper cloth) may be wound in sequence to prepare a molded body. After that, a jacket is put on and the mold is placed in a vulcanizing can, vulcanized at a temperature of about 120 to 200 ° C. (particularly 150 to 180 ° C.) to prepare a belt sleeve, and then made into a V shape using a cutter or the like. It may be cut.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following examples, the raw materials used in the examples, the measurement method or the evaluation method for each physical property are shown below. Unless otherwise specified, "parts" and "%" are based on mass.

[material]
Chloroprene rubber: "Denka Chloroprene DCR" manufactured by Denka Co., Ltd.
Aramid short fiber: "Conex short fiber" manufactured by Teijin Techno Products Co., Ltd., average fiber length 3 mm, average fiber diameter 14 μm
Vinyl Pyridine-Styrene-butadiene Copolymer Latex: Made by Zeon Corporation Graphene: Made by Graphene Platform Co., Ltd. "GNH-X1"
Graphite: "AT-20" manufactured by Oriental Sangyo Co., Ltd.
Ultra High Molecular Weight Polyethylene (UHMW-PE): "GUR-4150" manufactured by Ticona Engineering Polymers
Unfired low molecular weight PTFE: "KTL-8F" manufactured by Kitamura Co., Ltd.
Plasticizer: DIC Corporation, Sebacate oil Carbon black: Tokai Carbon Co., Ltd. "Seast 3"
Silica: "Nipsil VN3" manufactured by Tosoh Silica Co., Ltd.
Anti-aging agent: "Non-flex OD3" manufactured by Seiko Chemical Co., Ltd.
Core wire: A twisted cord in which 1,000 denier PET fibers are twisted in a 2 x 3 twisted structure with a total denier 6,000 cord twisted with an upper twist coefficient of 3.0 and a lower twist coefficient of 3.0.

[Friction coefficient and wear amount]
The rubber compositions for the compressed rubber layer of Examples and Comparative Examples were vulcanized at 153 ° C. for 30 minutes to prepare test pieces having a width of 10 mm, a length of 20 mm, and a thickness of 4 mm. A sliding friction and wear tester that can reciprocate the test piece attached to the upper part at a constant speed by pressing the mating material attached to the lower base base against the test piece attached to the upper part with a constant surface pressure. The test was carried out under the conditions of a speed of 10 m / min, a surface pressure of 0.5 MPa, a temperature of 70 ° C., and a running time of 20 hours. The material of the mating material was SUS304. For the friction coefficient, the voltage of the load cell was sampled every 10 seconds, and the average value for a test time of 20 hours was calculated. The amount of wear was measured by measuring the amount of weight loss of the test piece before and after the test.

[Durable running test (side pressure resistance)]
As shown in FIG. 3, the endurance running test was carried out using a two-axis running tester including a driving (Dr.) pulley 12 having a diameter of 50 mm and a driven (Dn.) Pulley 13 having a diameter of 125 mm. A low-edge cogged V-belt 11 is hung on each of the pulleys 12 and 13, the rotation speed of the drive pulley 12 is 5000 rpm, a load of 10 Nm is applied to the driven pulley 13, and the belt 11 is operated at an ambient temperature of 80 ° C. for a maximum of 40 hours. I let it run. The belt surface temperature during running reached a maximum of 120 ° C. By visually observing the side surface of the cog portion of the low-edge cogged V-belt 11 after running, the crack generation ratio per 100 cog portions (the number ratio of the cog portions where cracks originated from short fibers) was calculated. It was evaluated according to the following criteria.

⊚: Crack occurrence is 0%
◯: Crack occurrence is more than 0% and less than 10% ×: Crack occurrence is 10% or more.

Examples 1-10 and Comparative Examples 1-5
(Formation of rubber layer)
The rubber compositions of Table 1 (adhesive rubber layer) and Table 2 (compressed rubber layer and stretched rubber layer) are each rubber-kneaded using a known method such as a Banbury mixer, and the kneaded rubber is passed through a calendar roll. A rolled rubber sheet (sheet for adhesive rubber layer, sheet for compressed rubber layer, sheet for stretch rubber layer) was prepared. The short fibers were bonded with an RFL solution (containing resorcin and formaldehyde and vinylpyridine-styrene-butadiene rubber latex as latex), and short fibers having a solid content of 6% by mass were used. As the RFL solution, 2.6 parts by mass of resorcin, 1.4 parts by mass of 37% formalin, 17.2 parts by mass of vinylpyridine-styrene-butadiene copolymer latex, and 78.8 parts by mass of water were used.

(Manufacturing of friction transmission belt)
A laminate of a reinforcing cloth to be a lower cloth and a sheet for a compressed rubber layer (unvulcanized rubber) is installed in a flat cogged mold in which teeth and grooves are alternately arranged with the reinforcing cloth facing down. A cog pad (not completely vulcanized and in a semi-vulcanized state) having a cog portion molded by pressing and pressing at 75 ° C. was produced. Next, both ends of the cog pad were cut vertically from the top of the cog ridge.

A cylindrical mold is covered with an inner mother mold in which teeth and grooves are alternately arranged, and the cog pad is wound by engaging with the teeth and the groove and joined at the top of the cog ridge, and the wrapped cog pad is used. After laminating the adhesive rubber layer sheet (lower adhesive rubber: unvulcanized rubber) on top of it, the core wire is spun in a spiral shape, and the adhesive rubber layer sheet (upper adhesive rubber: for the adhesive rubber layer) is placed on top of this. A molded product was prepared by sequentially winding a stretch rubber layer sheet (unvulcanized rubber) and a reinforcing cloth (upper cloth) as an upper cloth (same as the sheet). Then, a jacket was put on and the mold was placed in a vulcanization can, and vulcanization was performed at a temperature of 160 ° C. for 20 minutes to obtain a belt sleeve. This sleeve is cut into a V-shaped cross-sectional shape with a predetermined width in the longitudinal direction of the belt with a cutter, and both side surfaces of the belt are polished to form a belt having the structure shown in FIG. 1, that is, a speed change belt having a cog on the inner peripheral side of the belt. A low-edge cogged V-belt (size: upper width 22.0 mm, thickness 11.0 mm, outer circumference length 800 mm) was produced.

Table 2 shows the measurement results of the friction coefficient and the amount of wear of the rubber composition for the compressed rubber layer, and Table 2 also shows the results of the durability running test of the obtained friction transmission belt.

In Comparative Example 1 containing no graphene and solid lubricant, the coefficient of friction was high and many cracks were generated in the durability running test. It is probable that the rubber was hardened and deteriorated due to the heat generated by the rubber being bent in the reverse direction due to the high coefficient of friction.

In Examples 1 to 3 containing graphene, the coefficient of friction was sufficiently reduced and the amount of wear was also small. In addition, no cracks occurred in the endurance running test. In particular, since a large effect can be obtained by adding a small amount as in Examples 1 and 2, it is considered that the possibility of becoming a crack starting point can be suppressed without significantly affecting the workability and physical properties of rubber. Be done.

In Example 4 in which 10 parts by mass of graphene was blended, the coefficient of friction was significantly reduced and the amount of wear was also the smallest. However, it is probable that in the endurance running test, cracks were generated in a small amount, and the friction coefficient was lowered to an appropriate value or more, so that slip was generated and the rubber was thermally deteriorated.

Comparative Examples 2 and 3 are belts using graphite as a solid lubricant, but the effect of lowering the coefficient of friction is hardly exhibited by adding a small amount, and even when a large amount is added, graphene is added. No sufficient decrease in the coefficient of friction was observed, and cracks occurred. Since graphite has a structure in which graphene is layered, the inner layer cannot exert any effect, and it is considered that even if the same weight is added, the effect is less likely to be obtained than graphene. Comparative Example 4 is a belt containing ultra-high molecular weight polyethylene, but a sufficient friction coefficient reducing effect was not observed as in graphite. Comparative Example 5 is a belt in which ultra-high molecular weight polyethylene is used in combination with graphite, but similarly, a sufficient effect of reducing the coefficient of friction was not observed.

Example 5 uses graphene in combination with graphite, Example 6 uses graphene in combination with ultra-high molecular weight polyethylene, Example 7 uses unfired low molecular weight PTFE in combination, and Example 8 uses graphene, ultra high molecular weight polyethylene, and unfired low. Although the belt contains three types of molecular weight PTFE, it does not interfere with each other, and the coefficient of friction can be further reduced as compared with the case where graphene is used alone. In this way, it is possible to obtain the target friction coefficient by variously changing the mixing ratio of the solid lubricant.

Example 9 is a belt that does not contain short fibers and contains 1 part by mass of graphene with respect to 100 parts by mass of chloroprene rubber. Compared with Example 1 containing both graphene and short fibers, the coefficient of friction was slightly higher, but no cracks occurred in the endurance running test.

Example 10 is a belt containing 40 parts by mass of short fibers and 1 part by mass of graphene with respect to 100 parts by mass of chloroprene rubber. Compared with Example 1 containing 15 parts by mass of short fibers, the friction coefficient was small and the amount of wear was also small, but a small amount of cracks occurred in the durability running test. It is considered that this is because the bending fatigue resistance decreased as the amount of short fibers added increased.

From the results of Examples 1 and 9 to 10, high wear resistance, lateral pressure resistance and slidability are exhibited by adding graphene even if the proportion of short fibers is small or the short fibers are not contained. It was found that the characteristics could be improved and the characteristics could be improved in a well-balanced manner.

The friction transmission belt of the present invention can be applied to, for example, a V belt (wrapped V belt, low edge V belt, low edge cogged V belt), V ribbed belt, flat belt and the like. In particular, V-belts (transmission belts) used in transmissions (continuously variable transmissions) whose gear ratio changes steplessly while the belt is running, for example, stepless motorcycles, ATVs (four-wheel buggies), snowmobiles, etc. It is preferably applied to low-edge cogged V-belts and low-edge double-cogged V-belts used in transmissions.

1 ... Friction transmission belt 2, 6 ... Reinforcing cloth 3 ... Stretch rubber layer 4 ... Adhesive rubber layer 4a ... Core body 5 ... Compressed rubber layer

Claims (7)

A friction transmission belt including a compression rubber layer having a friction transmission surface at least partially in contact with a pulley, and the friction transmission surface of the compression rubber layer is vulcanization of a rubber composition containing a rubber component and graphenes. Formed of things ,
The rubber component is chloroprene rubber,
The ratio of the graphenes is 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.
The compressed rubber layer further contains short fibers, and the ratio of the short fibers is 12 to 40 parts by mass with respect to 100 parts by mass of the rubber component.
Friction transmission belt that is a V-belt . Friction transmission belt according to claim 1 Symbol placement average particle diameter of the graphene compound is 0.1 to 3 m. The friction transmission belt according to claim 1 or 2, wherein the short fibers are oriented in the belt width direction. The friction transmission belt according to any one of claims 1 to 3, wherein the ratio of short fibers is 30 parts by mass or less with respect to 100 parts by mass of the rubber component. The invention according to any one of claims 1 to 4 , wherein the ratio of graphenes is 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component, and the compressed rubber layer further contains a solid lubricant and / or a friction modifier. Friction transmission belt. The friction transmission belt according to claim 5 , wherein the ratio of graphenes is 1 to 50 parts by mass with respect to 100 parts by mass in total of the solid lubricant and the friction modifier. The friction transmission belt according to any one of claims 1 to 6 , which is a low-edge cogged V-belt.

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