JP6175113B2 - Friction transmission belt - Google Patents

Description

  The present invention relates to a friction transmission belt used for driving an automobile engine auxiliary machine, and more specifically, while maintaining belt performance such as fuel saving and wear resistance, the friction state of the friction transmission surface is stabilized and sound generation resistance is improved. It is related with the friction transmission belt which can improve.

  In the rubber industry field, high functionality and high performance are desired especially for automobile parts. One of the rubber products used for such automobile parts is a friction transmission belt, and this friction transmission belt is widely used for power transmission for driving auxiliary equipment such as an air compressor and an alternator of an automobile. As this type of belt, a V-ribbed belt in which ribs are provided along the longitudinal direction of the belt is known, but in addition to belt performance such as fuel saving and wear resistance, the V-ribbed belt has sound generation resistance. Required. In particular, when traveling under water, the generation of stick-slip noise is a problem. Specifically, if the wettability of the friction transmission surface is low and the water ingress between the belt and the pulley is not uniform, the friction coefficient is high in the area where water has not entered (dry state), and the area where water has entered (covered) In the water state), the friction coefficient is partially lowered, the friction state becomes unstable, and a stick-slip sound is generated.

  In JP 2008-185162 A (Patent Document 1), at least the friction transmission surface is composed of a rubber composition in which 1 to 25 parts by mass of a surfactant is blended with 100 parts by mass of an ethylene / α-olefin elastomer. An improved friction transmission belt is disclosed. This friction transmission belt can increase the affinity between water (ethylene-α-olefin elastomer) that forms the friction transmission surface and water by adding a surfactant, and reduces noise caused by stick-slip. This improves the sound resistance when wet.

  However, in this belt, although the surfactant exuded on the friction transmission surface stabilizes the friction state between the belt and the pulley, the behavior of the surfactant in the rubber is unstable, and the internal loss (tan δ) Increases, the torcross becomes larger, the rubber strength decreases, and the wear resistance may not be maintained.

  In JP 2006-118661 A (Patent Document 2), in a power transmission belt in which a compression rubber layer is disposed on the belt bottom surface side of a core wire, an RFL-treated gelable polyvinyl alcohol fiber is applied to the compression rubber layer. A transmission belt is disclosed in which the short fibers made of are embedded so as to be exposed on the surface of the compressed rubber layer. In this document, the exposed polyvinyl alcohol short fiber absorbs water and gels, so even if a large amount of water enters, the water film breaks through the water layer generated at the interface between the belt and the pulley. It is described that a reduction in transmission capability and abnormal noise due to the slip caused by the slip are prevented. Further, in the examples, as an evaluation of the sound production performance, the sound production limit tension at the time of water injection is measured by rotating the belt with a biaxial testing machine.

  However, since the short fibers contained in this transmission belt are gelable polyvinyl alcohol fibers, the sound resistance cannot be improved. That is, in the example of Patent Document 2, the load at the time of 2% slip at the time of water injection is measured, but the load becomes larger and the friction coefficient at the time of water injection becomes larger than that of the comparative example (blended nylon fiber). ing. However, in an actual vehicle engine, since there is a rotational fluctuation, if the friction coefficient at the time of water injection is high, sound generation due to stick-slip is likely to occur. For this reason, it is necessary to increase the affinity between water and the rubber that forms the friction transmission surface, to form a uniform water film, to reduce the friction coefficient during water injection, and to reduce the change in the friction coefficient with respect to the sliding speed. . However, in the short fiber of Patent Document 2, since the short fiber that has absorbed water and gelled protrudes on the friction transmission surface and breaks through the water film, the uniform water film itself cannot be formed and the friction state is stabilized. I can't. Therefore, sound resistance is not sufficient in an actual vehicle engine with rotational fluctuation.

  Moreover, although it can be estimated that the gelled short fibers are softened by water absorption, the abrasion resistance cannot be maintained because the short fibers protruding during belt transmission are worn away.

  Further, short fibers are less likely to be dispersed in the compressed rubber layer than particles, and processability is low. Further, the short fibers dispersed in the rubber have a small contact area with the rubber and become a smooth contact surface, so that the adhesion to the rubber is lowered, and the resorcin-formalin-latex (RFL) treatment is performed to improve the adhesion. Surface treatment such as is necessary.

  Japanese Patent Application Laid-Open No. 2008-157445 (Patent Document 3) discloses that at least a part of a friction transmission surface is 5 to 50 masses of a water-soluble polymer having a melting point or a softening point of 80 ° C. or less with respect to 100 parts by mass of rubber. A friction transmission belt composed of a rubber composition containing a part is disclosed. In this document, polyethylene oxide is described as the water-soluble polymer.

  However, since this water-soluble polymer melts during vulcanization of the belt, it is dispersed throughout the compressed rubber layer, but the internal loss (tan δ) increases because the melted water-soluble polymer inhibits rubber cross-linking. The torcross becomes larger. In addition, in the Example of patent document 3, although polyvinyl alcohol is mix | blended as a water-soluble polymer, it is described as a comparative example with a low pronunciation limit tension at the time of water injection, and the details are also unknown.

JP 2008-185162 A (Claims) JP 2006-118661 A (Claim 1, paragraphs [0005] [0006] [0009]) JP 2008-157445 A (Claims, Examples)

  Accordingly, an object of the present invention is to provide a friction transmission belt that can improve the sound resistance by stabilizing the friction state of the friction transmission surface while maintaining the belt performance such as fuel saving and wear resistance.

  Another object of the present invention is to provide a friction transmission belt capable of suppressing sound generation due to slip between a friction transmission surface and a pulley during flooding.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that when the compression layer of the friction transmission belt is formed of a rubber composition containing a polymer component and polyvinyl alcohol-based resin particles, fuel economy and wear resistance are improved. The present invention has been completed by finding that the sound transmission can be improved by stabilizing the friction state of the friction transmission surface while maintaining the belt performance.

  That is, the friction transmission belt of the present invention includes a compression layer formed of a rubber composition having a transmission surface at least partially in contact with the pulley and containing a polymer component and polyvinyl alcohol resin particles. The average aspect ratio of the polyvinyl alcohol resin particles is preferably 10 or less. The saponification degree of the vinyl alcohol unit of the polyvinyl alcohol resin particles is preferably about 86 to 97 mol%. As for the viscosity average polymerization degree of the said polyvinyl alcohol-type resin particle, about 300-3500 are preferable. The melting point of the polyvinyl alcohol resin particles is preferably higher than the vulcanization temperature of the belt. The solubility of the polyvinyl alcohol resin particles in water at 20 ° C. is preferably 60% by mass or more. The polyvinyl alcohol resin particles are preferably polyvinyl alcohol resin particles modified with a hydrophobic group. The proportion of the polyvinyl alcohol resin particles is preferably about 5 to 30 parts by mass with respect to 100 parts by mass of the polymer component. The polyvinyl alcohol-based resin particles are preferably dispersed and exposed on the transmission surface. It is preferable that the compressed layer further includes a reinforcing material. The polymer component is preferably an ethylene-α-olefin elastomer.

  The friction transmission belt of the present invention further includes a core and a stretch layer that forms the back surface of the belt, a compression layer is formed on one surface of the stretch layer, and the belt is between the stretch layer and the compression layer. The core body is preferably embedded along the longitudinal direction. The friction transmission belt of the present invention is preferably a V-ribbed belt.

  In the present invention, since the compressed layer contains the polymer component and the polyvinyl alcohol resin particles in combination, the belt performance such as fuel saving and wear resistance is maintained (the performance does not deteriorate due to the rubber cross-linking inhibition). ) As it is, the frictional state of the friction transmission surface can be stabilized to improve sound resistance (especially sound resistance when wet). In particular, the polyvinyl alcohol resin particles are appropriately dissolved in water to form a uniform water film on the friction transmission surface, or sound generation due to slip between the friction transmission surface and the pulley during water can be suppressed.

FIG. 1 is a schematic sectional view showing an example of the V-ribbed belt of the present invention. FIG. 2 is a schematic view for explaining a contact angle measurement method in the embodiment. FIG. 3 is a schematic diagram for explaining a method of measuring torcross in the embodiment. FIG. 4 is a schematic diagram for explaining a misalignment pronunciation test in the embodiment. FIG. 5 is a graph showing the contact angle with water in the vulcanized rubber sheet obtained in the example. FIG. 6 is a graph showing the relationship between the friction coefficient and the sliding speed of the vulcanized rubber sheet obtained in the example. FIG. 7 is a graph showing the sound generation limit angle of the belt obtained in the example.

  Hereinafter, the structure of the friction transmission belt of the present invention and the method for manufacturing the friction transmission belt of the present invention will be described with reference to the drawings as appropriate.

[Structure of friction transmission belt]
The friction transmission belt of the present invention usually has a stretch layer, a compression layer formed on one surface of the stretch layer, and a core embedded along the longitudinal direction of the belt between the stretch layer and the compression layer. It has a body (heart wire). Specifically, the friction transmission belt of the present invention includes a stretch layer that forms an outer peripheral surface, a compression layer that is formed on one surface of the stretch layer and forms an inner peripheral surface, and between the stretch layer and the compression layer. And a core body extending in the longitudinal direction. The friction transmission belt of the present invention may further have an adhesive rubber layer (adhesive layer) interposed between the stretch layer and the compression layer, and the core body is embedded in the adhesive rubber layer. May be.

  The type of the friction transmission belt of the present invention is not particularly limited, and includes a V belt [a low edge belt (a low edge belt having a V-shaped cross section, etc.), a low edge cogged belt (both the inner peripheral side or the inner peripheral side and the outer peripheral side of the low edge belt). Low-edge cogged belt having a cog formed on the surface thereof]], V-ribbed belt, flat belt, and the like. Of these belts, a V-ribbed belt having high transmission efficiency is preferable.

  The form in particular of a V ribbed belt is not restrict | limited, For example, the form shown in FIG. 1 is illustrated. FIG. 1 is a schematic sectional view showing an example of a friction transmission belt of the present invention. A friction transmission belt shown in FIG. 1 includes a compression layer 2, an adhesive layer 4 in which a core body 1 is embedded in the belt longitudinal direction, a cover canvas (woven fabric) in order from the belt lower surface (inner circumferential surface) to the belt upper surface (back surface). , A knitted fabric, a non-woven fabric, etc.). A plurality of V-shaped grooves extending in the longitudinal direction of the belt are formed in the compression layer 2, and a plurality of ribs 3 (four in the example shown in FIG. 1) having a V-shaped cross section (reverse trapezoid) are formed between the grooves. ), And the two inclined surfaces (surfaces) of the rib 3 form a friction transmission surface and contact the pulley to transmit power (friction transmission).

  The friction transmission belt of the present invention is not limited to this configuration, and it is sufficient that at least a part of the friction transmission belt has a compression layer having a transmission surface that can come into contact with the pulley. Typically, the stretch layer and the compression layer are interposed therebetween. What is necessary is just to provide the core body embed | buried along a belt longitudinal direction. In the friction transmission belt of the present invention, for example, the stretch layer 5 may be formed of a rubber composition, or the core body 1 may be embedded between the stretch layer 5 and the compression layer 2 without providing the adhesive layer 4. Good. Further, the adhesive layer 4 is provided on either the compression layer 2 or the stretch layer 5, and the core 1 is disposed between the adhesive layer 4 (compression layer 2 side) and the stretch layer 5, or the adhesive layer 4 (stretch layer 5 side). ) And the compression layer 2 may be embedded. Further, a form in which powdery fibers (for example, cotton, nylon, aramid, etc.) are planted on the surface of the rib 3 (particularly, a friction transmission surface) may be used, or a form in which a lubricant or the like is spray applied may be used.

  Note that at least the compression layer only needs to be formed of the rubber composition described in detail below, and the stretch layer and the adhesive layer may not be formed of the same rubber composition as the compression layer. . Note that the rubber composition forming the stretch layer and the adhesive layer need not contain polyvinyl alcohol resin particles.

  Although it does not specifically limit as a core, Usually, the core wire (twisted cord) arranged at predetermined intervals in the belt width direction can be used. As the core wire, high-modulus fibers, for example, the above-mentioned polyester fibers (polyalkylene arylate fibers), synthetic fibers such as aramid fibers, inorganic fibers such as carbon fibers, etc. are widely used, and polyester fibers (polyethylene terephthalate fibers, polyethylene naphthalates). Phthalate fibers) and aramid fibers are preferred. The fiber may be a multifilament yarn, for example, a multifilament yarn having a fineness of 2000 to 10000 denier (particularly 4000 to 8000 denier).

  As the core wire, a twisted cord using multifilament yarn (for example, various twists, single twists, rung twists, etc.) can be used. The average wire diameter (fiber diameter of the twisted cord) of the core wire may be, for example, about 0.5 to 3 mm, preferably about 0.6 to 2 mm, and more preferably about 0.7 to 1.5 mm. The core wire may be embedded in the longitudinal direction of the belt, and one or a plurality of core wires may be embedded in parallel at a predetermined pitch parallel to the longitudinal direction of the belt.

  In order to improve the adhesion to the polymer component, the core wire may be embedded between the stretched layer and the compressed layer (especially the adhesive layer) after being subjected to various adhesion treatments with an epoxy compound, an isocyanate compound, or the like. .

  Further, the stretch layer may have a reinforcing cloth, for example, a cloth material (preferably a woven cloth) such as a woven cloth, a wide angle sail cloth, a knitted cloth, and a non-woven cloth. If necessary, the reinforcing fabric may be laminated on the surface of the stretched rubber layer by performing the above-described adhesion treatment.

[Compression layer]
The friction transmission belt according to the present invention includes a compression layer having a transmission surface at least partially in contact with the pulley, and the compression layer is formed of a rubber composition containing a polymer component and polyvinyl alcohol resin particles. Yes.

(Polymer component)
Examples of the polymer component include known rubber components and / or elastomers such as diene rubber [natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (nitrile rubber), hydrogenated nitrile. Rubber (including mixed polymers of hydrogenated nitrile rubber and unsaturated carboxylic acid metal salt), etc.], ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber Examples thereof include silicone rubber, urethane rubber, and fluorine rubber. These polymer components can be used alone or in combination of two or more. Among these polymer components, no harmful halogen is contained, ozone resistance, heat resistance, cold resistance, and economical efficiency, ethylene-α-olefin elastomers (ethylene-propylene rubber (EPR), Ethylene-α-olefin rubbers such as ethylene-propylene-diene copolymers (EPDM, etc.) are preferred.

(Polyvinyl alcohol resin particles)
In the present invention, by blending the polyvinyl alcohol-based resin particles with the polymer component, the particles can be dispersed substantially uniformly on the polished friction transmission surface and exposed without protruding. Furthermore, the polyvinyl alcohol-based resin is water-soluble, and can improve the wettability (affinity between rubber and water) of the friction transmission surface of the compression layer with respect to water. For this reason, even if water enters during traveling, the water film spreads uniformly between the belt and the pulley, and the frictional state is stabilized to suppress sound generation due to self-excited vibration. In particular, even when there is a rotational fluctuation as in an actual vehicle engine, it is possible to reduce the change in the friction coefficient with respect to the sliding speed, to reduce the noise caused by stick-slip, and to improve the sound resistance when wet. Furthermore, since the polyvinyl alcohol-based resin particles do not hinder the reinforcing effect of the reinforcing material on the polymer component in the rubber composition forming the compression layer, the internal loss (tan δ) can be kept low.

  As a polyvinyl alcohol-type resin which comprises a polyvinyl alcohol-type resin particle, the vinyl alcohol unit should just be included as a main unit, and in addition to a vinyl alcohol unit, the other copolymerizable unit may be further included.

Examples of monomers constituting other copolymerizable units include olefins (such as α-C _2-10 olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexene), unsaturated carboxylic acids [ (Meth) acrylic acid, (meth) acrylic acid methyl, (meth) acrylic acid C _1-6 alkyl ester such as ethyl (meth) acrylate, (anhydrous) maleic acid, etc.], vinyl ethers (methyl vinyl ether, ethyl vinyl ether, C _1-6 alkyl vinyl ethers such as propyl vinyl ether, C _2-6 alkanediol-vinyl ethers such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, 1,4-butanediol vinyl ether), unsaturated sulfonic acids (ethylene Sulfonic acid, allyl sulphone Etc. phosphate) and the like. These monomers can be used alone or in combination of two or more. Among these monomers, α-C _2-4 olefins such as ethylene and propylene are widely used.

  The proportion of other copolymerizable units may be 50 mol% or less, for example, 0 to 30 mol%, preferably 0.1 to 20 mol%, more preferably 1 to 10 mol, based on all units. %. The polyvinyl alcohol-based resin may be a homopolymer composed of vinyl alcohol units alone.

In the polyvinyl alcohol resin, the vinyl alcohol unit may be modified with a hydrophobic group. Examples of the hydrophobic group include a C _1-10 alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a hexyl group, a cycloalkyl group such as a cyclohexyl group, and an aryl group such as a phenyl group. Can be mentioned. These hydrophobic groups can be used alone or in combination of two or more. Of these hydrophobic groups, C _2-4 alkyl groups such as ethyl group and propyl group are preferred.

  In the present invention, by adjusting the proportion of copolymerizable units and hydrophobic groups, the solubility of polyvinyl alcohol resin particles in water can be adjusted, and torcross can be suppressed.

  The saponification degree of the vinyl alcohol unit of the polyvinyl alcohol resin particles may be 85 mol% or more, for example, 85 to 99.7 mol%, preferably 86 to 97 mol%, more preferably 86.5 to 93 mol. % (Especially 86.5 to 89.5 mol%). In the present invention, a saponification degree of 97 mol% or less is preferable, and a partially saponified product (86.5 to 89.5 mol%) is particularly preferable because a uniform water film can be easily formed on the friction transmission surface. The saponification degree of the completely saponified product may be 97.5 mol% or more (particularly 98 mol% or more).

  The viscosity average polymerization degree of the polyvinyl alcohol resin particles is, for example, about 300 to 3,500, preferably about 400 to 3,200, and more preferably about 500 to 3,000. If the degree of polymerization is too large, it is difficult to form a uniform water film on the friction transmission surface, and if it is too small, it may be difficult to maintain the particle shape. In the present invention, the viscosity average degree of polymerization can be measured by a method according to JIS K6726 (1994).

  The melting point of the polyvinyl alcohol-based resin particles only needs to be higher than the vulcanization temperature of the belt, and may be, for example, 10 ° C. or higher (particularly 50 ° C. or higher) higher than the vulcanization temperature of the belt. 180 degreeC or more may be sufficient as melting | fusing point of the particle | grains of polyvinyl alcohol-type resin, for example, 180-300 degreeC, Preferably it is 200-280 degreeC, More preferably, about 210-250 degreeC may be sufficient. If the melting point is too low, the particles may be melted by vulcanization, and it may be difficult to uniformly disperse in the rubber composition.

  The solubility of polyvinyl alcohol resin particles in water at 20 ° C. is 5% by mass or more (particularly 10% by mass or more, for example, 30% by mass or more (particularly 50% by mass or more), preferably 60% by mass or more ( For example, it may be about 60 to 99% by mass), and more preferably about 80% by mass or more (for example, 80 to 95% by mass). If the solubility is too low, the wettability of the friction transmission surface at a lower temperature range (for example, near room temperature) may be reduced, and the sound resistance may be reduced.

  The number average particle diameter of the polyvinyl alcohol resin particles is, for example, about 10 to 300 μm, preferably about 15 to 200 μm, and more preferably about 20 to 100 μm (for example, 50 to 100 μm). In addition, the number average particle diameter of the polyvinyl alcohol resin particles can improve sound resistance (especially sound resistance when wet), and drop off of particles during belt running and generation of cracks between particles and rubber. In terms of suppression, the particle size may be relatively small, for example, about 10 to 100 μm, preferably about 20 to 80 μm, and more preferably about 30 to 50 μm (particularly about 35 to 45 μm). The reason why small-diameter particles can improve sound resistance is that the uniform dispersion improves water wettability, and can suppress the drop-off of particles during belt running and the occurrence of cracks between particles and rubber. Can be estimated. If the particle size is too large, the mechanical properties and durability of the compressed layer may be reduced. On the other hand, if the particle size is too small, it becomes difficult to uniformly fill and disperse the rubber composition, and the sound resistance may be reduced. In the present invention, the number average particle diameter is represented by an average value of the major axis and the minor axis when the particles are anisotropic.

  The maximum particle size of the polyvinyl alcohol resin particles may be 500 μm or less, for example, 400 μm or less, preferably 350 μm or less (for example, 300 μm or less), more preferably 200 μm or less (particularly 180 μm or less). The minimum particle size of the polyvinyl alcohol resin particles may be 1 μm or more, for example, 3 μm or more, preferably 5 μm or more, and more preferably 8 μm or more. If the maximum particle size is too large, the sound resistance may decrease.

  The average aspect ratio (ratio of major axis to minor axis) of the polyvinyl alcohol resin particles may be 10 or less (for example, 1 to 10), for example, 1 to 5, preferably 1 to 3, and more preferably 1 to 2. (For example, about 1.2 to 1.9). Further, the aspect ratio of the polyvinyl alcohol-based resin particles is, for example, 1.5 to 5, preferably 1.6 to 3, and more preferably 1.8 to 2.5, from the viewpoint of improving the sound resistance when wet. It may be a degree. If the aspect ratio is too large, stress concentration occurs at the interface when the rubber composition is deformed, and the elongation at break of the rubber composition may be reduced.

  In the present invention, the number average particle diameter and the average aspect ratio can be measured by a method of measuring dimensions based on a scanning electron micrograph taken at 50 times.

  Since the polyvinyl alcohol-based resin particles have such a shape, shearing and tensile stress concentration at the interface between the rubber and the polyvinyl alcohol hardly occurs when the rubber composition is deformed. Therefore, the particles can be fixed in the rubber composition without performing an adhesion treatment with an adhesive component such as a resorcin-formalin-latex (RFL) liquid. In addition, since polyvinyl alcohol has an acetic acid group (hydrophobic group) in addition to a hydroxyl group (hydrophilic group), it has a surface activity and can be easily and uniformly dispersed in the polymer component forming the compression layer.

  The proportion of the polyvinyl alcohol-based resin particles may be about 1 part by mass or more with respect to 100 parts by mass of the polymer component, for example, 1 to 50 parts by mass, preferably 3 to 40 parts by mass (for example, 5 to 30 parts by mass). More preferably, it is about 5-35 mass parts (especially 10-30 mass parts). Further, the proportion of the polyvinyl alcohol-based resin particles is preferably larger from the viewpoint of improving the sound resistance when wet, and is preferably 10 parts by mass or more, for example, 10 to 50 parts by mass with respect to 100 parts by mass of the polymer component. Part, preferably 15 to 40 parts by weight, more preferably about 20 to 30 parts by weight. If the proportion of the polyvinyl alcohol-based resin particles is too large, the mechanical properties of the compressed layer are deteriorated. If the proportion is too small, the sound resistance may be deteriorated.

(Reinforcing material)
The rubber composition may contain a reinforcing material in order to improve the mechanical strength of the compression layer. Reinforcing materials include conventional fillers and reinforcing fibers.

  Examples of the filler include carbonaceous materials (carbon black, graphite, etc.), metal compounds or synthetic ceramics (metal oxides such as calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, calcium silicate) Metal silicates such as aluminum silicate, metal carbides such as silicon carbide and tungsten carbide, metal nitrides such as titanium nitride, aluminum nitride and boron nitride, metal carbonates such as magnesium carbonate and calcium carbonate, calcium sulfate and sulfuric acid Metal sulfates such as barium), mineral materials (zeolite, diatomaceous earth, calcined siliceous clay, activated clay, alumina, silica, talc, mica, kaolin, sericite, bentonite, montmorillonite, smectite, clay, etc.) Can be mentioned. These fillers can be used alone or in combination of two or more. The shape of the filler is granular, plate-like, or indefinite shape. The number average primary particle size of the filler can be appropriately selected from the range of about 10 nm to 10 μm depending on the type. Of these fillers, carbonaceous materials such as carbon black and mineral materials such as silica are widely used, and carbon black is preferred.

  Carbon black has a large particle size, particularly a large particle size carbon black having an iodine adsorption of 40 mg / g or less in order to improve fuel economy by reducing internal heat generation of the rubber composition forming the compression layer. It is preferable to include. Examples of the large particle size carbon black include FEF, GPF, APF, SRF-LM, SRF-HM and the like. These carbon blacks can be used alone or in combination of two or more. The number average primary particle size of the large particle size carbon black may be, for example, about 40 to 200 nm, preferably about 45 to 150 nm, and more preferably about 50 to 125 nm.

  Since the large particle diameter carbon black has a small reinforcing effect and poor wear resistance, it is preferable to use a small particle diameter carbon black (iodine adsorption amount higher than 40 mg / g) having a small particle diameter and a high reinforcing effect. By using at least two types of carbon blacks having different particle diameters, it is possible to achieve both fuel economy (effects by large particle diameter carbon black) and wear resistance (effects by small particle diameter carbon black). Examples of the small particle size carbon black include SAF, ISAF-HM, ISAF-LM, HAF-LS, HAF, and HAF-HS. These carbon blacks can be used alone or in combination of two or more. The number average primary particle size of the small particle size carbon black may be less than 40 nm, for example, about 5 to 38 nm, preferably about 10 to 35 nm, and more preferably about 15 to 30 nm.

  The ratio of the average particle size of the large particle size carbon black to the average particle size of the small particle size carbon black is the former / the latter = 1.5 / 1 to 3/1, preferably 1.7 / 1 to 2. It may be about 7/1, more preferably about 1.8 / 1 to 2.5 / 1.

  The mass ratio between the large particle size carbon black and the small particle size carbon black is within a range where both fuel saving and wear resistance can be achieved, for example, the former / the latter = 20/80 to 55/45, preferably 25. / 75 to 50/50, more preferably about 30/70 to 50/50. If the proportion of carbon black with a small particle size is too large, the internal heat generation (tan δ) of the rubber composition (compressed layer) increases, resulting in a reduction in fuel consumption and a large amount of large particle size carbon black. If it is too high, the wear resistance is reduced due to insufficient reinforcement.

Examples of reinforcing fibers include polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), polyamide fibers (polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers, aramid fibers, etc.), polyester fibers (polyethylene terephthalate (PET) fibers, polyethylene). Synthetic fibers such as C _2-4 alkylene C _6-14 arylate fibers such as naphthalate (PEN) fibers], vinylon fibers, polyparaphenylene benzobisoxazole (PBO) fibers; natural fibers such as cotton, hemp, wool An inorganic fiber such as carbon fiber can be exemplified. These fibers can be used alone or in combination of two or more.

  Among these short fibers, at least one selected from polyamide fibers such as aramid fibers, polyester fibers, and vinylon fibers is preferable. The reinforcing fiber may be fibrillated.

  The reinforcing fibers may be usually contained in the compressed layer in the form of short fibers, and the average length of the short fibers is, for example, 0.1 to 20 mm, preferably 0.5 to 15 mm, more preferably 1 to 10 mm. It may be about 1 to 5 mm (for example, 2 to 4 mm). The average fiber diameter of the reinforcing fibers is, for example, about 1 to 100 μm, preferably 3 to 50 μm, more preferably about 5 to 40 μm (particularly 10 to 30 μm).

  The proportion of the reinforcing material may be 40 parts by mass or more with respect to 100 parts by mass of the polymer component, for example, 45 to 100 parts by mass, preferably 50 to 90 parts by mass, more preferably 55 to 80 parts by mass (particularly 60 parts). (About 70 parts by mass). In the present invention, even if the ratio of the reinforcing material is large, the torcross can be reduced.

  The proportion of the filler may be 10 parts by mass or more with respect to 100 parts by mass of the polymer component, for example, 20 to 100 parts by mass, preferably 30 to 90 parts by mass, more preferably 35 to 80 parts by mass (particularly 40 parts by mass). (About 70 parts by mass).

  The proportion of the reinforcing fibers may be 80 parts by mass or less (for example, 0 to 80 parts by mass) with respect to 100 parts by mass of the polymer component, for example, 60 parts by mass or less (for example, 1 to 60 parts by mass), preferably 50 parts by mass. Part or less (for example, 5 to 50 parts by mass), more preferably about 40 parts by mass or less (for example, 10 to 40 parts by mass). If the proportion of reinforcing fibers is too large, there is a possibility that the torque cross cannot be reduced.

(Other additives or compounding agents)
The rubber composition may contain a conventional additive or compounding agent as necessary. Examples of the compounding agent include a vulcanizing agent or a crosslinking agent [for example, oximes (such as quinonedioxime), guanidines (such as diphenylguanidine), metal oxides (such as magnesium oxide and zinc oxide), and organic peroxides (such as Diacyl peroxide, peroxy ester, dialkyl peroxide, etc.)], vulcanization aid, vulcanization accelerator, vulcanization retarder, plasticizer, softener (oils such as paraffin oil and naphthenic oil), Processing agents or processing aids (stearic acid, metal stearate, wax, paraffin, etc.), anti-aging agents (aromatic amines, benzimidazole anti-aging agents, etc.), adhesion improvers [resorcin-formaldehyde cocondensates , Melamine resins such as hexamethoxymethyl melamine, co-condensates thereof (resorcin-melamine- Mualdehyde co-condensate, etc.), colorants, tackifiers, coupling agents (silane coupling agents, etc.), stabilizers (antioxidants, UV absorbers, heat stabilizers, etc.), lubricants, flame retardants, An antistatic agent etc. can be illustrated. These compounding agents can be used singly or in combination of two or more, and are appropriately selected and used according to the kind, application and performance of the polymer component.

  In the present invention, the polyvinyl alcohol resin particles can form a uniform water film on the friction transmission surface when wet. Therefore, from the viewpoint of the effect of reducing torcross, it is preferable that the compression layer substantially does not contain a surfactant other than the polyvinyl alcohol resin, and the ratio of the surfactant other than the polyvinyl alcohol resin forms the compression layer. It may be 10% by mass or less (especially 1% by mass or less) with respect to the entire rubber composition, and is substantially free of surfactants other than polyvinyl alcohol resin (except for inevitable impurities). preferable.

(Loss tangent inside the compression layer)
The compression layer of the present invention preferably has a low internal loss tangent or dielectric loss tangent (tan δ). The loss tangent (tan δ) is obtained by dividing the loss elastic modulus (E ″) by the storage elastic modulus (E ′), and the maximum energy stored as energy dissipated (lost) as heat during one vibration cycle. It is expressed as a ratio to energy, and is a measure of energy loss, that is, tan δ can be used to numerically represent an index by which vibration energy applied to the rubber composition is dissipated as heat. In the preferred embodiment of the present invention, attention is paid to tan δ at the temperature at which the belt normally travels (for example, a temperature range of 40 to 120 ° C.). Specifically, for example, tan δ of the compression layer at 40 ° C. and a frequency of 10 Hz is set to 0 to improve fuel efficiency. It can be selected from the range of about 0.08 to 0.17, for example, 0.09 to 0.165, preferably 0.095 to 0.16, more preferably 0.1 to 0.15 (particularly 0.1 to 0.1. 13) About.

[Belt manufacturing method]
The production method of the friction transmission belt of the present invention is not particularly limited, and a known or conventional method can be adopted. For example, a compression layer, an adhesive layer in which a core body is embedded, and an extension layer are formed and laminated with an unvulcanized rubber composition, and the laminate is molded into a cylindrical shape with a molding die and vulcanized. Then, the sleeve can be formed and formed by cutting the vulcanized sleeve to a predetermined width. More specifically, the V-ribbed belt can be manufactured by the following method.

(First manufacturing method)
First, a stretch layer sheet is wound around a cylindrical molding mold having a smooth surface, and a core wire (twisted cord) forming a core on the sheet is spun spirally, and further, an adhesive layer sheet and a compression layer Sheets are sequentially wound to produce a molded body. Thereafter, a jacket for vulcanization is placed on the molded body, the mold (molding die) is accommodated in a vulcanizing can, vulcanized under predetermined vulcanization conditions, and then removed from the molding mold to form a cylindrical shape. A vulcanized rubber sleeve is obtained. Then, the outer surface (compression layer) of the vulcanized rubber sleeve is polished by a grinding wheel to form a plurality of ribs, and then the vulcanized rubber sleeve is cut to a predetermined width in the belt longitudinal direction using a cutter. Finish in a V-ribbed belt. By reversing the cut belt, a V-ribbed belt provided with a compression layer having a rib portion on the inner peripheral surface can be obtained.

(Second manufacturing method)
First, a cylindrical inner mold with a flexible jacket attached to the outer peripheral surface is used as the inner mold, and an unvulcanized stretch layer sheet is wound around the outer peripheral flexible jacket, and a core is formed on the sheet. A core is spun into a spiral shape, and an unvulcanized compressed layer sheet is wound around to produce a laminate. Next, as an outer mold that can be attached to the inner mold, a cylindrical outer mold in which a plurality of rib molds are engraved on the inner peripheral surface is used, and an inner mold in which the laminate is wound is provided in the outer mold. Install concentrically. Thereafter, the flexible jacket is expanded toward the inner peripheral surface (rib type) of the outer mold, and the laminate (compressed layer) is pressed into the rib mold and vulcanized. Then, after extracting the inner mold from the outer mold and removing the vulcanized rubber sleeve having a plurality of ribs from the outer mold, the vulcanized rubber sleeve is cut to a predetermined width in the longitudinal direction of the belt using a cutter. Finish the ribbed belt. In the second manufacturing method, a laminated body including a stretch layer, a core body, and a compression layer can be expanded at a time to be finished into a sleeve (or a V-ribbed belt) having a plurality of ribs.

(Third production method)
In relation to the second manufacturing method, for example, the method disclosed in JP-A-2004-82702 (expanding only the compression layer to form a preform (semi-vulcanized state), then the stretch layer and the core body) May be expanded and pressure-bonded to the preform, and vulcanized and integrated into a V-ribbed belt).

  Of these production methods, the first production method is preferred, in which the compressed layer can be polished to sufficiently protrude the short fibers on the friction transmission surface. In the second and third manufacturing methods, the compression layer is press-fitted into the rib mold to form the rib, so that the exposure amount of the polyvinyl alcohol resin particles is reduced. However, the compression layer formed by these methods The transmission surface may be polished or ground to expose the polyvinyl alcohol resin particles.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the detail of the component of a rubber composition in an Example and the evaluation method of the measured evaluation item are shown below.

[Ingredients of rubber composition]
EPDM: “EPT2060M” manufactured by Mitsui Chemicals, Inc.
PVA-A: Completely saponified product of polyvinyl alcohol, saponification degree 98.7 to 99.7 mol%, viscosity average polymerization degree 1700, Denkapoval K-17C manufactured by Denki Kagaku Kogyo Co., Ltd.
PVA-B: polyvinyl alcohol partially saponified product, degree of saponification of 86.5-89.5 mol%, viscosity average degree of polymerization of 600, “Denkapoval B-05S” manufactured by Denki Kagaku Kogyo Co., Ltd.
PVA-C: modified product of polyvinyl alcohol hydrophobic group, saponification degree 93.0 to 97.0 mol%, viscosity average polymerization degree 1700, type of hydrophobic group: alkyl group, Denkapoval F- manufactured by Denki Kagaku Kogyo Co., Ltd. 300S "
PVA-D: completely saponified product of polyvinyl alcohol, saponification degree 99 mol% or more, viscosity average polymerization degree 1700, Denka Poval K-177 manufactured by Denki Kagaku Kogyo Co., Ltd.
Surfactant: Polyoxyalkylene alkyl ether, “New Coal 2308-LY” manufactured by Nippon Emulsifier Co., Ltd.
Carbon black HAF: “Seast 3” manufactured by Tokai Carbon Co., Ltd., average particle size 28 nm
Carbon Black GPF: “Seast V” manufactured by Tokai Carbon Co., Ltd., average particle size 62 nm
Nylon short fiber: 66 nylon, average fiber diameter 27 μm, average fiber length 3 mm
Cotton short fiber: Denim, average fiber diameter 13μm, average fiber length 6mm
Vinylon short fibers: average fiber diameter 26 μm, average fiber length 6 mm
Organic peroxide: Dicumyl peroxide Co-crosslinking agent: Dibenzoyl quinone dioxime, “Barunok DMG” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Anti-aging agent A: Diphenylamine-based anti-aging agent (“NOCRACK CD” manufactured by Ouchi Shinsei Chemical Co., Ltd.)
Anti-aging agent B: Mercaptobenzimidazole type anti-aging agent (“NOCRACK MB” manufactured by Ouchi Shinsei Chemical Co., Ltd.).

[William wear]
It measured according to JISK6264 (1993) using the vulcanized rubber sheet.

[Viscoelasticity (tan δ)]
A test piece was collected from the vulcanized rubber sheet and used as a test piece. The test piece has a thickness of 2.0 mm, a width of 4.0 mm, and a length of 40 mm. Then, the test piece is chucked and fixed to the chuck of the viscoelasticity measuring apparatus (“VR-7121” manufactured by Ueshima Seisakusho Co., Ltd.) with a distance between chucks of 15 mm, an initial strain (static strain) of 2.0% is applied, and the frequency is 10 Hz. Dynamic strain of 1.0% (that is, while applying a strain of ± 1.0% in the longitudinal direction with the initial strain of 2.0% as a central position or a reference position), 25 at a heating rate of 1 ° C./min The tan δ (loss tangent) at 40 ° C., 100 ° C. was determined.

[Contact angle]
As shown in FIG. 2, the contact angle θ between the surface of the vulcanized rubber sheet and water (the angle formed by the tangent of the water droplet and the surface) is calculated using the θ / 2 method based on a projection photograph of water droplets dropped on the surface. And can be obtained from the following equation.
θ = 2θ ₁ (1)
tan θ ₁ = h / r → θ ₁ = tan ⁻¹ (h / r) (2)
(In the formula, θ ₁ is the angle of a straight line connecting the end point (left end point in FIG. 2) and the apex of the water drop to the surface, h is the height of the water drop, and r is the radius of the water drop.)
By substituting equation (2) into equation (1), the following equation (3) is obtained.
θ = 2 tan ⁻¹ (h / r) (3)
The contact angle is measured using a fully automatic contact angle meter (“CA-W type” manufactured by Kyowa Interface Science Co., Ltd.), measuring r and h from a projected photograph of a dropped water drop, using equation (3). Calculated. The measurement calculated the contact angle immediately after dropping (after 1 second) and after 60 seconds. The smaller the contact angle θ, the better the surface has affinity with water.

[Coefficient of friction]
A disk-shaped test piece having a diameter of 8 mm and a thickness of 2 mm was collected from the vulcanized rubber sheet, and the frictional force was measured using a pin-on-disk friction coefficient measuring device to calculate the friction coefficient. Specifically, the test piece is pressed with a load of 2.192 kgf / cm ² with a counterpart material (SUS304) having a surface roughness Ra of 0.8 μm, and water is applied to the test piece only when measuring at a water volume of 30 ml / min. Friction force was measured at a friction speed of 0 to 2.0 m / sec while pouring water, and the slope (μ-V characteristic) of the coefficient of friction with respect to the friction speed (sliding speed with respect to the counterpart material) was calculated by the least square method. In addition, this inclination represents the change of the friction coefficient with respect to the sliding speed.

[6% slip wear]
A V-ribbed belt is hung on each pulley of a testing machine in which a driving pulley (diameter 80 mm), a driven pulley (diameter 80 mm), and a tension pulley (diameter 120 mm) are arranged in order, and the winding angle of the belt around the tension pulley is 90 °. Under room temperature conditions, the belt was run for 24 hours while automatically adjusting the belt tension so that the rotational speed of the driving pulley was 3000 rpm, the torque of the driven pulley was 9.8 N · m, and the belt slip ratio was 6%. The belt weight before and after the running test was measured, and the belt weight loss (belt weight before running−belt weight after running) divided by the belt weight before running was calculated as the wear rate.

[Torcross (Transmission loss)]
As shown in FIG. 3, a V-ribbed belt is hung on a two-axis running test machine composed of a driving (Dr) pulley having a diameter of 55 mm and a driven (Dn) pulley having a diameter of 55 mm, and a tension of 500 N / belt. Then, a predetermined initial tension was applied to the V-ribbed belt, and the difference between the driving torque and the driven torque when the driving pulley was rotated at 2000 rpm with no driven pulley loaded was calculated as the torque cross. In addition, the torque cross obtained by this measurement includes the torque cross resulting from the bearing of the testing machine in addition to the torque cross resulting from the V-ribbed belt. Therefore, a metal belt (material: maraging steel) in which the torque cross as the belt is considered to be substantially 0 was run in advance, and the difference between the driving torque and the driven torque was obtained as the torque cross (bearing loss) caused by the bearing. Then, a value obtained by subtracting the torque cross (bearing loss) due to the bearing from the torque cross calculated by running the V-ribbed belt (the torque cross resulting from the belt and the bearing) was obtained as the torque cross resulting from the belt alone. The torcross (bearing loss) is the torcross when the metal belt is run at a predetermined initial tension (for example, when a V-ribbed belt is run at an initial tension of 500 N / one belt, the metal belt is run at this initial tension. The torcross when it is made a bearing loss). The smaller the torque cross of this V-ribbed belt, the better the fuel economy.

[Sounding limit angle test: Misalignment pronunciation test]
The misalignment sound generation evaluation test (sound generation limit angle) includes a 101 mm diameter drive pulley (Dr.), a 70 mm diameter idler pulley (IDL1), a 120 mm diameter misalignment pulley (W / P), and a 70 mm diameter idler pulley (IDL2). ), A tension pulley (Ten) having a diameter of 61 mm, and an idler pulley (IDL3) having a diameter of 70 mm were arranged in this order, and the test was performed using a testing machine whose layout is shown in FIG. The axis separation (span length) of the idler pulley (IDL1) and the misalignment pulley was set to 135 mm, and all the pulleys were adjusted to be located on the same plane (misalignment angle 0 °).

  That is, a V-ribbed belt is suspended on each pulley of the test machine, and tension is applied so that the rotational speed of the drive pulley is 1000 rpm and the belt tension is 6 kgf / Rib (rib) under room temperature conditions. When 5 cc of water is periodically poured into the friction transmission surface of the V-ribbed belt (approximately every 30 seconds) and the belt is driven by misalignment (the misalignment pulley is shifted toward the front). The angle (pronunciation limit angle) at the time of occurrence (near the misalignment pulley entrance) was determined. The greater the pronunciation limit angle, the better the silence. Normally, at around 3 °, the belt is detached from the pulley (that is, the rib is displaced), and the power is not normally transmitted.

[Shape of polyvinyl alcohol particles]
Using a scanning electron microscope ("VE-7800" manufactured by Keyence Co., Ltd.), the polyvinyl alcohol particles as a raw material were photographed at a magnification of 50 times, and then the particle size ( (Major axis and minor axis) were measured, and the average particle diameter and aspect ratio of the polyvinyl alcohol particles were calculated. The results are shown in Table 1.

[Comparative Examples 1-2 and Examples 1-5]
The rubber composition shown in Table 1 was kneaded with a Banbury mixer, and the kneaded rubber was passed through a calender roll to prepare an unvulcanized rolled rubber sheet having a predetermined thickness. After collecting predetermined dimensions of the obtained sheet, press vulcanization was performed under vulcanization conditions of 165 ° C. and 30 minutes to prepare a vulcanized rubber sheet.

  Table 2 shows the results of measuring the amount of William wear and the viscoelasticity (tan δ) of the obtained vulcanized rubber sheet. Moreover, the result of having measured the contact angle with water is shown in Table 2 and FIG. Furthermore, the result of having measured the friction coefficient is shown in Table 2 and FIG.

  As is apparent from the results in Table 2, the amount of William wear in Examples 1 to 6 was smaller than that in the comparative example.

  In Examples 1 to 6, tan δ was smaller than that of Comparative Example 1 (containing a surfactant). In Example 4, tan δ was slightly larger than the other examples.

  Moreover, Examples 1-6 increased the storage elastic modulus rather than the comparative example 1 which mix | blended surfactant. This indicates that the strength does not decrease even when polyvinyl alcohol (PVA) is blended, and this also correlates with the results of the abrasion test.

  Further, as apparent from the results of Table 2 and FIG. 5, the contact angle with water was the smallest in Example 4 and the wettability was good.

  Furthermore, as is clear from the results of Table 2 and FIG. 6, Example 4 had the smallest friction coefficient change (inclination of μ-V curve) when wet (WET). That is, the sheet of Example 4 had the most stable friction state when wet.

  In addition, from the comparison between Example 3 and Example 6, in the case of a completely saponified polyvinyl alcohol product, the change in the coefficient of friction at the time of being wet (WET) (inclination of the μ-V curve) uses particles having a small particle size. Example 6 was smaller.

[Comparative Examples 3 to 4 and Examples 7 to 15]
The rubber composition shown in Table 3 was kneaded with a Banbury mixer, and the kneaded rubber was passed through a calender roll to prepare an unvulcanized rolled rubber sheet (sheet for compression layer) having a predetermined thickness. Further, in the rubber composition shown in Table 3, a rubber composition containing no short fibers, a surfactant and polyvinyl alcohol (PVA) is used, and a sheet for an adhesive layer and a sheet for an extension layer are formed in the same manner as the sheet for a compression layer. Was made.

  Next, using these sheets, belts were produced by the first production method described above. That is, first, a stretch layer sheet is wound around a cylindrical molding mold having a smooth surface, a processing rope is spun spirally on the stretch layer sheet, and an adhesive layer sheet and a compression layer sheet are sequentially wound. A molded body was formed. After that, a vulcanization jacket is placed on the molded body, the mold is placed on a vulcanizing can, vulcanized under predetermined vulcanization conditions, and then removed from the molding mold to form a cylindrical vulcanized rubber sleeve. Obtained. Then, the outer surface (compression layer) of the vulcanized rubber sleeve is polished with a grinding wheel at predetermined intervals to form a plurality of ribs, and then the vulcanized rubber sleeve is formed with a predetermined width in the belt longitudinal direction using a cutter. It was cut into a V-ribbed belt having 6 ribs in the width direction and a circumference of 1100 mm.

  Furthermore, Table 3 shows the results of preparing vulcanized rubber sheets and test pieces from the rubber composition collected from the compressed layer sheets and measuring 6% slip wear, belt torque and viscoelasticity (tan δ). Table 3 and FIG. 7 show the results of measuring the belt sounding limit angle.

  As is apparent from the results in Table 3, the 6% slip wear amount in the example was smaller than that in the comparative example.

  Moreover, the Example had the same transmission loss (torque cloth) as the comparative example 3 which mix | blended surfactant, and was equivalent to the comparative example 4 which does not contain PVA and surfactant.

  Further, as apparent from the results of Table 3 and FIG. 7, the belts of Examples 7 to 8 and 11 have a high sounding limit angle in both the dry state (DRY) and the wet state (WET), and the soundproofing property. Was good. It is considered that the hydrophilicity was improved by the blending of PVA and the friction state was stabilized. Furthermore, in the WET state, all of the examples had better sound resistance than Comparative Example 4.

  Further, as apparent from the results in Table 3, the tan δ of the example was smaller than that of Comparative Example 3 and slightly larger than that of Comparative Example 4. That is, even if PVA was blended, tan δ was not increased as much as the blend of surfactant, and was correlated with the result of transmission loss.

  Furthermore, as is clear from the results in Table 3, the storage modulus increased in Examples compared to Comparative Examples 3 and 4. That is, even if PVA was blended, it was shown that the strength did not decrease, and was correlated with the result of the wear test.

  Further, as is clear from the results of Examples, the larger the amount of PVA, the larger the sounding limit angle when wet, and the sound resistance was excellent.

  The friction transmission belt of the present invention can be used as a friction transmission belt such as various belts that require sound resistance, such as a V belt and a V-ribbed belt. Moreover, since the friction transmission belt of the present invention can improve the quietness at the time of flooding, it can be suitably used for a transmission device used outdoors such as an automobile, a motorcycle, an agricultural machine, and the like.

DESCRIPTION OF SYMBOLS 1 ... Core body 2 ... Compression layer 3 ... Rib 4 ... Adhesive layer 5 ... Stretch layer

Claims (12)

A friction transmission belt including a compression layer formed of a rubber composition having a transmission surface capable of contacting at least a part of a pulley and containing a polymer component and polyvinyl alcohol resin particles ;
A friction transmission belt having an average aspect ratio of polyvinyl alcohol resin particles of 10 or less . Friction transmission belt according to claim 1 Symbol placement saponification degree of the vinyl alcohol units of the polyvinyl alcohol-based resin particles is from 86 to 97 mol%. The friction transmission belt according to claim 1 or 2, wherein the polyvinyl alcohol resin particles have a viscosity average polymerization degree of 300 to 3,500. The friction transmission belt according to any one of claims 1 to 3 , wherein the melting point of the polyvinyl alcohol-based resin particles is higher than the vulcanization temperature of the belt. The friction transmission belt according to any one of claims 1 to 4 , wherein the polyvinyl alcohol resin particles have a solubility in water at 20 ° C of 60% by mass or more. The friction transmission belt according to any one of claims 1 to 5 , wherein the polyvinyl alcohol resin particles are polyvinyl alcohol resin particles modified with a hydrophobic group. The ratio of polyvinyl alcohol-type resin particle is 5-30 mass parts with respect to 100 mass parts of polymer components, The friction transmission belt in any one of Claims 1-6 . The friction transmission belt according to any one of claims 1 to 7 , wherein the polyvinyl alcohol resin particles are dispersedly exposed on the transmission surface. The friction transmission belt according to any one of claims 1 to 8 , wherein the compression layer further includes a reinforcing material. The friction transmission belt according to any one of claims 1 to 9 , wherein the polymer component is an ethylene-α-olefin elastomer. The core further includes a core and a stretch layer that forms a back surface of the belt, and a compression layer is formed on one surface of the stretch layer, and the core is disposed between the stretch layer and the compression layer along the longitudinal direction of the belt. friction transmission belt according to any one of claims 1-10 but which is embedded. The friction transmission belt according to any one of claims 1 to 11 , which is a V-ribbed belt.

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