JP6291470B2 - Friction transmission belt and manufacturing method thereof - Google Patents

Description

  The present invention relates to a friction transmission belt used for driving an automobile engine accessory and the like, and more particularly, to a friction transmission belt capable of stabilizing a friction state of a friction transmission surface and improving sound resistance and a manufacturing method thereof.

  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 rubber strength decreases because the behavior of the surfactant in the rubber is unstable. There is a possibility that the wear resistance cannot be maintained. Furthermore, since the surfactant is blended in the entire compressed rubber layer, the mechanical properties (such as strength and elongation) of the compressed rubber layer are lowered.

  In JP 2006-118661 A (Patent Document 2), in a transmission belt in which a compression rubber layer is disposed on the belt bottom surface side of the core wire, the compression rubber layer is treated with resorcin-formalin-latex (RFL). A power transmission belt is disclosed in which short fibers made of gelable polyvinyl alcohol fiber 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. In addition, 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 a surface treatment such as RFL treatment is required to improve the adhesion. It becomes. Furthermore, since the short fibers are blended in the entire compressed rubber layer, the mechanical properties are deteriorated.

  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 the water-soluble polymer is blended in the entire compressed rubber layer, the mechanical properties are deteriorated. 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.

  WO 2011/114727 pamphlet (Patent Document 4) includes a compressed rubber layer that contacts a pulley and transmits power, and the compressed rubber layer has a relatively high plasticizer content and is a granular ultra-high A friction transmission belt having a surface rubber layer containing a molecular weight polyethylene resin and an inner rubber layer having a relatively small plasticizer content is disclosed. JP 2013-113343 A (Patent Document 5) includes a compression rubber layer having a friction transmission surface for engaging with or contacting a pulley, and the friction transmission surface is formed of a polyethylene resin. A friction transmission belt with a lubricant attached is disclosed.

  However, with polyethylene-based resins such as ultra-high molecular weight polyethylene resins, sound resistance and wear resistance can be improved by reducing the friction coefficient, but sound generation when exposed to water cannot be suppressed at a high level.

JP 2008-185162 A (Claims) JP 2006-118661 A (Claim 1, paragraphs [0005] [0006] [0009]) JP 2008-157445 A (Claims, Examples) WO 2011/114727 pamphlet (Claims 1 and 6) JP 2013-113343 A (Claim 1)

  Accordingly, an object of the present invention is to provide a friction transmission belt that can stabilize the friction state of the friction transmission surface and improve the sound resistance, and a method of manufacturing the same.

  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 while maintaining mechanical properties such as strength and elongation, and a method for manufacturing the same. It is in.

  Still another object of the present invention is to provide a friction transmission belt capable of improving sound resistance while maintaining belt performance such as wear resistance and a method for manufacturing the same.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that when a surface layer containing a polyvinyl alcohol-based resin is laminated on the surface of the transmission surface of the compression rubber layer of the friction transmission belt, belts such as fuel saving and wear resistance can be obtained. The inventors have found that the sound resistance can be improved by stabilizing the friction state of the friction transmission surface while maintaining the performance, thereby completing the present invention.

That is, the friction transmission belt of the present invention is a friction transmission belt including a compression rubber layer formed of a rubber composition including at least a part of a transmission surface that can come into contact with a pulley and including a polymer component, A surface layer containing a polyvinyl alcohol-based resin is laminated on the surface of the transmission surface. The surface layer may be formed of a rubber composition containing polyvinyl alcohol resin particles and a polymer component. The polyvinyl alcohol resin particles may have an average aspect ratio of 10 or less. The surface layer may be formed of a polyvinyl alcohol resin. The polyvinyl alcohol resin particles may have the following characteristics (1) to (4).
(1) Saponification degree of vinyl alcohol unit is 86 to 97 mol% (2) Viscosity average polymerization degree is 300 to 3500 (3) Melting point is higher than vulcanization temperature of belt (4) 20 ° C The solubility in water is 60% by mass or more.

  The polyvinyl alcohol resin may be a polyvinyl alcohol resin modified with a hydrophobic group. The polymer component may be an ethylene-α-olefin elastomer. The compressed rubber layer may be a layer that does not contain a polyvinyl alcohol resin.

  The friction transmission belt of the present invention further includes a core and a stretched rubber layer that forms the back of the belt, a compressed rubber layer is formed on one surface of the stretched rubber layer, and the stretched rubber layer and the compressed rubber layer The core body may be embedded along the longitudinal direction of the belt. The friction transmission belt of the present invention may be a V-ribbed belt.

  The present invention includes a compressed rubber layer winding step of winding an unvulcanized rubber sheet around a cylindrical drum, and a vulcanization molding step of pressing the unvulcanized rubber sheet against a mold to vulcanize the compressed rubber layer winding. A method for manufacturing the friction transmission belt is also included in which the surface layer is formed in any one of the attaching step and the vulcanization forming step. In the compressed rubber layer winding step, a laminated sheet of an unvulcanized rubber layer for forming the surface layer and an unvulcanized rubber layer for forming the compressed rubber layer may be used as the unvulcanized rubber sheet. . Moreover, in the said compression rubber layer winding process, you may use the sheet | seat which apply | coated the polyvinyl alcohol-type resin particle to the surface of the unvulcanized rubber sheet for forming a compression rubber layer as an unvulcanized rubber sheet. Furthermore, in the vulcanization molding step, a mold in which polyvinyl alcohol-based resin particles are applied to the contact surface with the unvulcanized rubber sheet may be used as the mold.

  In the present invention, since the surface layer containing the polyvinyl alcohol-based resin is laminated on the surface of the transmission surface of the compression rubber layer of the friction transmission belt, the friction state of the friction transmission surface is stabilized and the sound resistance (especially when wet) (Pronunciation resistance) can be improved. In particular, because the surface layer contains a polyvinyl alcohol-based resin, while maintaining the mechanical properties such as strength and elongation, the polyvinyl alcohol-based resin is appropriately dissolved in water to form a uniform water film on the friction transmission surface, Sound generation due to slip between the friction transmission surface and the pulley during flooding can be suppressed. Furthermore, sound resistance can be improved while maintaining belt performance such as wear resistance (no performance degradation due to inhibition of rubber crosslinking).

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 misalignment pronunciation test in the embodiment.

[Surface]
The friction transmission belt according to the present invention includes a compression rubber layer having a transmission surface at least partially in contact with the pulley, and a surface layer containing a polyvinyl alcohol resin is laminated on the surface of the transmission surface. The polyvinyl alcohol-based resin is water-soluble, and can exist on the surface of the compressed rubber layer as a surface layer, thereby improving the wettability (affinity between rubber and water) of the friction transmission surface of the compressed rubber 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.

  The surface layer may be laminated on the transmission surface that can come into contact with the pulley, but may be laminated on the entire surface of the compressed rubber layer (the entire exposed surface) from the viewpoint of productivity.

  The surface layer only needs to contain a polyvinyl alcohol resin, but a surface layer (single layer) formed of a polyvinyl alcohol resin and a surface layer (composite) formed of a rubber composition containing polyvinyl alcohol resin particles and a polymer component. Layer).

(Single layer)
As a polyvinyl alcohol-type resin which comprises a single layer, what is necessary is just to contain the vinyl alcohol unit as a main unit, and in addition to the vinyl alcohol unit, you may further contain the other copolymerizable unit.

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 the copolymerizable unit and the hydrophobic group, the solubility of the polyvinyl alcohol resin in water can be adjusted, and tolcloth can be suppressed.

  The saponification degree of the vinyl alcohol unit of the polyvinyl alcohol resin may be 30 mol% or more, for example, 30 to 99.7 mol%, preferably 50 to 97 mol%, more preferably 60 to 93 mol% (particularly 80 to 89.5 mol%). The degree of saponification of the vinyl alcohol unit may be 85 mol% or more, for example, 85 to 99.7 mol%, preferably 86, in terms of improving sound resistance (especially sound resistance when wet). It is about -97 mol%, More preferably, it is about 86.5-93 mol% (especially 86.5-89.5 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. Further, the solubility in water is increased, the wettability with water is improved, and a uniform water film is formed between the belt and the pulley to stabilize the friction state. 50 to 80 mol%). 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-based resin is, for example, about 50 to 3,500, preferably about 100 to 3200, and more preferably about 200 to 3000. The viscosity average degree of polymerization is, for example, about 300 to 3,500, preferably 400 to 3200, more preferably 500 to 3000 (particularly 1000 to 2500) from the viewpoint of improving sound resistance (particularly sound resistance when wet). There may be. 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 a uniform layer shape (particle shape in the composite layer described later). is there. 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 resin is not particularly limited, and is, for example, a temperature lower than the vulcanization temperature of the belt [for example, a temperature lower by about 0 to 50 ° C. (especially about 5 to 30 ° C.) than the vulcanization temperature of the belt]. However, a temperature higher than the vulcanization temperature of the belt is preferable because the layer shape can be easily maintained even after vulcanization (in the composite layer described later, the particle shape is easily maintained). It may be higher than the vulcanization temperature by 10 ° C. or more (particularly 50 ° C. or more). The melting point of the polyvinyl alcohol resin may be, for example, 150 ° C. or higher (particularly 180 ° C. or higher), for example, 180 to 300 ° C., preferably 200 to 280 ° C., more preferably about 210 to 250 ° C. . If the melting point is too low, the layer shape may be deformed by vulcanization (in the composite layer described later, particles may be melted and it may be difficult to uniformly disperse in the rubber composition).

  The solubility of the polyvinyl alcohol resin particles in water at 20 ° C. may be 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, 60 to 99 mass%), more preferably about 80 mass% or more (for example, 80 to 95 mass%). If the belt gets wet, the belt temperature during running will drop, so if the solubility near room temperature is too low, the wettability of the friction transmission surface at lower temperatures (for example, near room temperature) will be reduced, and sound resistance will be increased. May decrease.

(Composite layer)
The composite layer is formed of a rubber composition containing the polyvinyl alcohol resin in the form of particles in addition to the polymer component.

(1) Polymer component As the polymer component, 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 polymer of hydrogenated nitrile rubber and unsaturated carboxylic acid metal salt)], ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin Examples thereof include rubber, acrylic rubber, 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.

(2) Polyvinyl alcohol-based resin particles In the composite layer, since the polyvinyl alcohol-based resin exists in the form of particles, the particles can be substantially uniformly dispersed on the transmission surface and exposed without protruding. Furthermore, in the composite layer, the dispersion form of the polyvinyl alcohol-based resin particles is not particularly limited, and the particles partially exposed on the surface of the composite layer and the particles completely embedded in the composite layer are mixed and substantially uniform. It may be in a dispersed form, or may be in a form in which only particles partially exposed on the surface of the composite layer are dispersed substantially uniformly. The former dispersion form can be easily prepared by forming a sheet of a rubber composition in which particles are previously dispersed, and the latter dispersion form is easily prepared by partially attaching the particles to the surface of the compressed rubber layer. it can.

  The polyvinyl alcohol resin constituting the polyvinyl alcohol resin particles is the same as the polyvinyl alcohol resin exemplified in the section of the single layer.

  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 (particularly about 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 rubber 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-based 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, it is 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 surface activity and can be easily and uniformly dispersed in the polymer component forming the surface layer.

  The ratio 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 small, the sound resistance may be lowered.

(3) Other additives The rubber composition may further include a reinforcing material and an additive (or compounding agent) exemplified in the section of the compressed rubber layer described later. Among these, it is preferable to include at least a vulcanizing agent, but from the viewpoints of adhesion between layers and productivity, the same reinforcing material and additive as the compressed rubber layer may be included. The ratio of the reinforcing material and the additive can also be selected from the range described in the compressed rubber layer, and may be the same ratio as the compressed rubber layer.

(Surface thickness)
The thickness (average thickness) of the surface layer can be selected from about 1 to 1500 μm. In the case of a single layer, it is, for example, 1 to 500 μm, preferably 5 to 300 μm, more preferably about 10 to 150 μm. It is 1500 micrometers, Preferably it is 150-800 micrometers, More preferably, it is about 200-600 micrometers. If the thickness of the surface layer is too thin, the effect of improving sound resistance may be reduced, and the durability of sound resistance may also be reduced. On the other hand, if the surface layer is too thick, the mechanical properties of the compressed rubber layer may be reduced.

  In the present invention, the average thickness of the surface layer is measured by observing the cross section of the compression rubber layer portion of the friction transmission belt using a scanning electron microscope, and the average value of 10 positions is calculated for the surface layer containing the polyvinyl alcohol-based resin. Was determined by

[Compressed rubber layer]
The compressed rubber layer is formed of a rubber composition containing a polymer component. The polymer component can use the polymer component illustrated by the term of the composite layer in the said surface layer, and a preferable polymer component is the same as that of a composite layer. From the viewpoint of interlayer adhesion, the same polymer component as the polymer component constituting the composite layer is preferred.

(Reinforcing material)
The rubber composition of the compressed rubber layer may contain a reinforcing material in order to improve mechanical strength. 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.

  The number average primary particle size of the carbon black can be selected from the range of about 5 to 200 nm, and is, for example, about 10 to 100 nm, more preferably about 15 to 80 nm (particularly 20 to 50 nm). If the particle size is too large, the mechanical properties of the compressed rubber layer may be reduced.

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). Poly C _2-4 alkylene C _6-14 arylate fiber such as naphthalate (PEN) fiber], synthetic fiber such as vinylon fiber, polyparaphenylene benzobisoxazole (PBO) fiber; natural such as cotton, hemp, wool Examples of fibers include inorganic fibers such as carbon fibers. 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 rubber 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 1. It is 10 mm and 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 is 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 to 70 parts by mass). Part) grade.

  The proportion of the filler is 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 to 70 parts by mass). Part) grade.

  The ratio of the reinforcing fiber is 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 or less ( For example, it is 5-50 mass parts), More preferably, it is about 40 mass parts or less (for example, 10-40 mass parts) grade.

(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, since the surface layer contains a polyvinyl alcohol-based resin, the compressed rubber layer does not need to contain a polyvinyl alcohol-based resin. It is preferable to contain a polyvinyl alcohol resin. The proportion of the polyvinyl alcohol resin (particularly polyvinyl alcohol resin particles) may be less than 50 parts by mass with respect to 100 parts by mass of the polymer component, for example, 20 parts by mass or less (for example, 0.001 to 20 parts by mass), preferably Is 10 parts by mass or less (for example, 0.005 to 10 parts by mass), more preferably about 5 parts by mass or less (for example, 0.01 to 5 parts by mass). From the viewpoint of mechanical properties, polyvinyl alcohol resin particles are used. It is preferable that it does not contain substantially, and it is especially preferable not to contain polyvinyl alcohol-type resin particles.

  Furthermore, in the present invention, a uniform water film can be formed on the frictional transmission surface when exposed to water by the polyvinyl alcohol resin of the surface layer. From the viewpoint of mechanical properties, the compressed rubber layer has a surface activity other than the polyvinyl alcohol resin. It is preferable that the agent is substantially not contained. In the compressed rubber layer, the ratio of the surfactant other than the polyvinyl alcohol-based resin may be 10% by mass or less (particularly 1% by mass or less) relative to the entire rubber composition forming the compressed rubber layer, and is substantially It is particularly preferable that no surfactant other than polyvinyl alcohol-based resin is included (except for inevitable impurities).

[Structure of friction transmission belt]
The friction transmission belt of the present invention usually includes an extended rubber layer, a compressed rubber layer laminated on one side of the extended rubber layer, a surface layer laminated on the transmission surface of the compressed rubber layer, and the extended rubber layer. And a core body (core wire) embedded along the longitudinal direction of the belt. Specifically, the friction transmission belt of the present invention includes an extended rubber layer that forms an outer peripheral surface, a compressed rubber layer that is laminated on one surface of the extended rubber layer and forms an inner peripheral surface, and the transmission of the compressed rubber layer. You may provide the surface layer laminated | stacked on the surface, and the core which extends in the longitudinal direction between the said extension | stretching rubber layer and a compression rubber layer. In addition, the friction transmission belt of the present invention may further include an adhesive rubber layer (adhesive layer) interposed between the stretch rubber layer and the compression rubber layer, and the core body is disposed in the adhesive rubber layer. It may be buried.

  The type of the friction transmission belt is not particularly limited, and a V belt [low edge belt (low edge belt having a V-shaped cross section, etc.), low edge cogged belt (cogs on both the inner peripheral side or the inner peripheral side and the outer peripheral side of the low edge belt). Formed low edge cogged belt)], 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. In this form, the V-ribbed belt 1 includes a surface layer 6, a compressed rubber layer 5, and an adhesive rubber layer 3 in which a core body 4 is embedded in the belt longitudinal direction from the belt lower surface (inner circumferential surface) to the belt upper surface (back surface). The stretched rubber layer 2 made of a cover canvas (woven fabric, knitted fabric, non-woven fabric, etc.) is laminated. A plurality of V-shaped grooves extending in the longitudinal direction of the belt are formed in the compressed rubber layer 5, and a plurality of ribs having a V-shaped section (reverse trapezoidal shape) are formed between the grooves. Two inclined surfaces (surfaces) form a friction transmission surface and contact the pulley to transmit power (friction transmission).

  The frictional power transmission belt of the present invention is not limited to this form, and may be provided with an extended rubber layer, a compressed rubber layer, and a core body embedded along the longitudinal direction of the belt. May be formed of a rubber composition, and the core body 4 may be embedded between the stretched rubber layer 2 and the compressed rubber layer 5 without providing the adhesive rubber layer 3. Further, the adhesive rubber layer 3 is provided on either the compressed rubber layer 5 or the stretched rubber layer 2, and the core body 4 is disposed between the adhesive rubber layer 3 (compressed rubber layer 5 side) and the stretched rubber layer 2, or the adhesive rubber. It may be embedded between the layer 3 (on the stretched rubber layer 2 side) and the compressed rubber layer 5. Further, the surface of the surface layer 6 (particularly, the friction transmission surface) may be a form in which powdery fibers (for example, cotton, nylon, aramid, etc.) are planted, or a form in which a lubricant or the like is applied by spraying.

  Note that at least the surface layer and the compressed rubber layer may be formed of the rubber composition, and the stretched rubber layer and the adhesive rubber layer may not be formed of the rubber composition of the surface layer and the compressed rubber layer. The rubber composition for forming the stretch rubber layer and the adhesive rubber layer is usually formed of a rubber composition for forming the compression rubber layer.

  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. For the core wire, high modulus fibers such as polyester fibers (polyalkylene arylate fibers), synthetic fibers such as aramid fibers, and inorganic fibers such as carbon fibers are widely used. Polyester fibers (polyethylene terephthalate fibers, polyethylene naphthalates) System 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 is embedded between the stretch rubber layer and the compression rubber layer (especially the adhesive rubber layer) after various adhesion treatments with epoxy compounds, isocyanate compounds, etc. May be.

  Further, the stretch rubber 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 or 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.

[Belt manufacturing method]
The manufacturing method of the friction transmission belt employs a method including a compression rubber layer winding step in which an unvulcanized rubber sheet is wound around a cylindrical drum, and a vulcanization molding step in which the unvulcanized rubber sheet is pressed against a mold and vulcanized. The surface layer is formed by any one of the compressed rubber layer winding step and the vulcanization molding step.

  Except for the method of forming the surface layer, there is no particular limitation as long as it is a method of molding with a mold, and a conventional method can be used. Conventional methods include, for example, a core spinning process for winding a core wire forming a core on a cylindrical drum, a compressed rubber layer winding step for winding an unvulcanized rubber sheet on the wound core wire, and the core A method including a vulcanization molding process in which a wire and the unvulcanized rubber sheet are pressed against a mold (pressed with a mold) and vulcanized can be used. As a pre-process of the wire spinning process, on a flexible jacket (bladder) mounted on a cylindrical molding drum, a member constituting an extended rubber layer (rubber sheet or reinforcing fabric), and if necessary an adhesive rubber layer A step of winding a rubber sheet for forming the core may be included, and the core wire may be further spirally spun on the wound member.

  Specifically, in the conventional method, first, a cylindrical inner mold having an outer peripheral surface with a flexible jacket is used as an inner mold, and an unvulcanized stretch rubber layer sheet is attached to the outer peripheral surface flexible jacket. A core is formed by winding, and a core wire forming a core is spun into a spiral shape, and an unvulcanized sheet for a compressed rubber layer 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 rubber layer) is press-fitted 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 this method, a laminated body including an extended rubber layer, a core body, and a compressed rubber layer can be expanded at a time to be finished into a sleeve having a plurality of ribs (or a V-ribbed belt).

  On the other hand, as another method, for example, the method disclosed in Japanese Patent Application Laid-Open No. 2004-82702 (only the compressed rubber layer is expanded to form a preform (semi-vulcanized state), and then the stretched rubber layer and the core are formed. A method of inflating and pressure-bonding to the preform, and vulcanizing and integrating to finish a V-ribbed belt) may be employed.

  The method for forming the surface layer can be incorporated into any one of the compression rubber layer winding step and the vulcanization molding step in such a conventional method. For example, (1) In the compression rubber layer winding step, A method of using a laminated sheet of an unvulcanized rubber layer (rubber composition) for forming a surface layer and an unvulcanized rubber layer for forming a compressed rubber layer as an unvulcanized rubber sheet, (2) a compressed rubber In the layer winding step, as a non-vulcanized rubber sheet, a method using a sheet in which polyvinyl alcohol resin particles are coated on the surface of an unvulcanized rubber sheet for forming a compressed rubber layer, (3) in a vulcanization molding step Examples of the mold include a method using a mold in which polyvinyl alcohol resin particles are coated on the contact surface with the unvulcanized rubber sheet.

  In the method (1), the method for preparing the laminated sheet is not particularly limited, and a conventional method can be used. For example, each unvulcanized sheet separately produced by rolling or the like may be laminated. It may be a molded laminated sheet. In the method (1), since the surface layer can be usually prepared with a rubber composition containing polyvinyl alcohol resin particles, the particles partially exposed on the surface and the particles completely embedded in the layer are mixed and substantially uniform. A composite layer having a dispersed form can be easily formed.

  In the methods (2) and (3), the polyvinyl alcohol-based resin particles may be applied (sprayed) or adhered (sprayed) to the particles themselves, or a liquid composition in which the particles are dispersed in a solvent is applied. Also good. Moreover, you may apply | coat or spray the liquid rubber composition (rubber paste) containing a polyvinyl alcohol-type resin particle.

  Examples of a method for spraying or spraying the polyvinyl alcohol resin particles themselves include an electrostatic coating method in which particles are charged and sprayed, a method using a method and an apparatus described in JP-A-2004-116755, and the like.

  Examples of the coating method include conventional methods such as a coater method, a casting method, a dip method, a spray method, and a spinner method. Of these methods, the coater method and the spray method are widely used. If necessary, the coating solution may be applied a plurality of times.

  Examples of the solvent constituting the liquid composition or the liquid rubber composition include water, alcohols (for example, alkanols such as ethanol and isopropanol), and hydrocarbons (for example, aromatic hydrocarbons such as toluene and xylene). ), Ethers (eg, chain ethers such as diethyl ether; cyclic ethers such as dioxane and tetrahydrofuran), ketones (eg, chain ketones such as acetone and methyl ethyl ketone; cyclic ketones such as cyclohexanone), esters (eg, General-purpose solvents such as acetate esters such as ethyl acetate), cellosolves (such as methyl cellosolve, ethyl cellosolve, butyl cellosolve), and carbitols. These solvents may be used alone or as a mixed solvent. These solvents can be selected depending on the application. For example, water and / or alcohols may be used to form a uniform single layer, or other solvents may be used to form a composite layer that maintains the particle shape. May be.

  Although the rubber component which forms a liquid rubber composition is not specifically limited, From the point of adhesiveness, the rubber component same as the rubber component which forms a compression rubber layer is preferable.

  In the methods (2) and (3), by increasing the coating thickness and the solid content concentration of the liquid composition, a single layer can be easily formed, and the particles themselves are partially dispersed on the transmission surface, or the liquid composition By reducing the solid content concentration, it is possible to easily form a composite layer having a form in which only particles partially exposed on the surface are dispersed substantially uniformly.

  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, degree of saponification 98.7 to 99.7 mol%, viscosity average degree of polymerization 1700, melting point 222 ° C., Denkapoval K-17C manufactured by Denki Kagaku Kogyo Co., Ltd.
PVA-B: partially saponified polyvinyl alcohol, degree of saponification of 86.5 to 89.5 mol%, viscosity average polymerization degree of 600, melting point of 193 ° C, Denkapoval B-05S manufactured by Denki Kagaku Kogyo Co., Ltd.
PVA-C: modified product of polyvinyl alcohol hydrophobic group, saponification degree 93.0-97.0 mol%, viscosity average polymerization degree 1700, melting point 206 ° C., type of hydrophobic group: alkyl group, manufactured by Denki Kagaku Kogyo Co., Ltd. Denkapoval F-300S "
PVA-D: Completely saponified product of polyvinyl alcohol, saponification degree 99 mol% or more, viscosity average polymerization degree 1700, melting point 222 ° C., “Denkapoval K-177” manufactured by Denki Kagaku Kogyo Co., Ltd.
PVA-E: Polyvinyl alcohol low saponification product, saponification degree 50 to 80 mol%, viscosity average polymerization degree 100 to 400, melting point 156 ° C., “JMR-10MD” manufactured by Nihon Acetate / Poval Co., Ltd.
Ultra high molecular weight polyethylene (PE): “GUR4150” manufactured by Hexa Industry, average particle size of 80 μm, melting point of 135 ° C.
Fluororesin (PTFE): “Fluon G190” manufactured by Asahi Glass Co., Ltd., average particle size 25 μm
Stearic acid: Tsubaki stearic acid manufactured by NOF Corporation
Zinc oxide: “Zinc oxide 3 types” manufactured by Shodo Chemical Industry Co., Ltd.
Carbon black HAF: “Seast 3” manufactured by Tokai Carbon Co., Ltd., average particle size 28 nm
Talc: “RL217” manufactured by Fuji Talc Kogyo Co., Ltd., median diameter 20 μm
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.)
Softener (paraffin oil): “Diana Process Oil” manufactured by Idemitsu Kosan Co., Ltd.
Co-crosslinking agent: dibenzoyl quinone dioxime, “Barunok DMG” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Organic peroxide: Dicumyl peroxide.

[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 an 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.

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

[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 are arranged in order, and the test machine shown in the layout in FIG. 3 is used to separate the idler pulley (IDL1) from the misalignment pulley. Length) was set to 135 mm, and all the pulleys were adjusted so as to be positioned 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.

[Preparation of rubber layer]
As the compression rubber layer and the surface layer, the rubber composition shown in Table 2 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 contact angle with water, the friction coefficient, the μ-V characteristic (change of the friction coefficient with respect to the sliding speed), and the amount of William wear of the obtained vulcanized rubber sheet.

  As is clear from the results in Table 2, rubber compositions B to H containing PVA resin particles have improved wettability with water and a change in friction coefficient compared to rubber composition A that does not contain PVA resin particles. (The slope of the μ-V curve) became smaller.

  On the other hand, the rubber composition I is excellent in wear resistance and has a μ-V characteristic smaller than that of other blends, but the friction coefficient itself is so small that when used on the belt transmission surface, the transmission performance is low. Conceivable. Furthermore, since the rubber composition I has a large contact angle (poor wettability with water), it is considered that the sound resistance when wet is lowered.

[Comparative Example 1]
The rubber composition A shown in Table 2 was kneaded with a Banbury mixer, and the kneaded rubber was passed through a calender roll to prepare an unvulcanized rolled rubber sheet (compressed rubber layer sheet) having a thickness of 2.3 mm. Further, by using the rubber composition A, an adhesive rubber layer sheet having a thickness of 0.3 mm and an extended rubber layer sheet having a thickness of 0.5 mm were prepared in the same manner as the compressed rubber layer sheet.

  Next, using these sheets, belts were produced by the above-described production method. That is, a stretch rubber layer sheet and an adhesive rubber layer sheet are sequentially wound around the outer periphery of a mold bladder having an air supply port and a top plate, and a core wire serving as a core is formed on the outer peripheral surface of the adhesive rubber layer sheet. After being wound in a spiral shape, a sheet for a compressed rubber layer was further wound on the core, and a belt sleeve was attached to the mold.

  Further, the mold around which the belt sleeve is wound is set in the vulcanization mold, and the bladder is expanded while being heated by the heating / cooling jacket having the heating / cooling medium introduction port, so that the belt sleeve is placed in the vulcanization mold. Vulcanization was performed by pressing against the peripheral surface and applying pressure. The vulcanization conditions were set at 165 ° C., 1.0 MPa, and 30 minutes. At this time, a groove was formed on the outer periphery of the belt sleeve as the concavo-convex portion for molding of the vulcanization bite into the belt sleeve from the outer periphery.

  Next, the mold was extracted from the vulcanization mold, the vulcanization belt sleeve remaining in the vulcanization mold was cooled with a heating / cooling jacket, and then the vulcanization belt sleeve was removed from the vulcanization mold. Then, this vulcanized belt sleeve was cut so as to be cut in a circle by a cutter, thereby obtaining a V-ribbed belt having 6 ribs in the width direction and a circumferential length of 1100 mm.

[Comparative Example 2]
After winding the sheet for the compressed rubber layer, using a powder coating device, spraying talc under the spraying rate of 100 g / m ² , except winding around the core so that the side with the talc attached is on the outside Obtained a V-ribbed belt in the same manner as in Comparative Example 1. A surface layer (single layer) formed of talc was laminated on the surface of the compression rubber layer of the obtained V-ribbed belt.

[Comparative Example 3]
A V-ribbed belt was obtained in the same manner as in Comparative Example 2 except that a fluororesin was used instead of talc. On the surface of the compression rubber layer of the obtained V-ribbed belt, a surface layer (single layer) formed of a fluororesin was laminated.

[Comparative Example 4]
Each of the rubber composition A and the rubber composition I and separately rolled with a rolling mill (the thickness of the sheet obtained by rolling the rubber composition A is 1.7 mm, the thickness of the sheet obtained by rolling the rubber composition I is 0.00 mm. 6 mm) was laminated to obtain a laminated sheet. A V-ribbed belt was obtained in the same manner as in Comparative Example 1 except that the layer formed of the rubber composition I was wound around the core so that the layer was on the outside.

[Example 1]
A V-ribbed belt was obtained in the same manner as in Comparative Example 4 except that the rubber composition E was used instead of the rubber composition I.

[Example 2]
A V-ribbed belt was obtained in the same manner as in Comparative Example 4 except that the rubber composition F was used instead of the rubber composition I.

[Example 3]
A V-ribbed belt was obtained in the same manner as in Comparative Example 4 except that the rubber composition D was used instead of the rubber composition I.

[Example 4]
A V-ribbed belt was obtained in the same manner as in Comparative Example 4 except that the rubber composition G was used instead of the rubber composition I.

[Example 5]
A V-ribbed belt was obtained in the same manner as in Comparative Example 4 except that the rubber composition H was used instead of the rubber composition I.

[Example 6]
A V-ribbed belt was obtained in the same manner as in Comparative Example 2 except that PVA-B was used instead of talc. A surface layer (single layer) formed of polyvinyl alcohol was laminated on the surface of the compression rubber layer of the obtained V-ribbed belt.

  Table 3 shows the measurement results of the sound generation limit angles of the belts obtained in the comparative examples and the examples.

  As is clear from the results in Table 3, the examples containing polyvinyl alcohol in the surface layer have higher sounding limit angles at the time of drying and when wet as compared with the comparative examples, and the sounding resistance was improved.

  In particular, when compared with the types of polyvinyl alcohol at the same blending amount, the sounding limit angle when wet is as follows: Hydrophobic group modification (PVA-C)> partial saponification (PVA-B)> complete saponification (small particle size PVA- D)> low saponification / low melting point (PVA-E)> complete saponification (large particle size PVA-A) in this order, and the hydrophobic group-modified product was most excellent in sound resistance when wet.

  In addition, from the comparison between Example 3 and Example 4, in the completely saponified polyvinyl alcohol product, the change in the coefficient of friction at the time of being wet (WET) (the slope of the μ-V curve) is small particles. Example 4 was smaller.

  Furthermore, from the results of Example 5, even with a low melting point polyvinyl alcohol low saponification product, the sound resistance when wet was good and practically usable. Because the degree of saponification is small, the solubility in water is increased, the wettability with water is improved, and a uniform water film is formed between the belt and the pulley to stabilize the friction state. Can be estimated. Further, even when the melting point of polyvinyl alcohol is lower than the vulcanization temperature of rubber and the degree of polymerization is low, even when particles dispersed in the rubber composition are melted by vulcanization, they are cooled and solidified while maintaining the dispersed state. Can be estimated.

  On the other hand, Comparative Examples 2 to 4 including particles other than polyvinyl alcohol on the surface layer and Comparative Example 1 not including particles had a smaller sounding limit angle when exposed to water and lower sounding resistance than Examples. .

  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 ... V-ribbed belt 2 ... Stretch rubber layer 3 ... Adhesive rubber layer 4 ... Core body 5 ... Compression rubber layer 6 ... Surface layer

Claims (11)

A friction transmission belt including a compression rubber layer formed of a rubber composition including at least a part of a transmission surface that can come into contact with a pulley and including a first polymer component , A friction transmission belt in which a surface layer formed of a rubber composition containing polyvinyl alcohol resin particles having an aspect ratio of 10 or less and a second polymer component is laminated. Polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin particles, friction transmission belt according to claim 1 Symbol mounting having the following characteristics (1) to (4).
(1) Saponification degree of vinyl alcohol unit is 86 to 97 mol% (2) Viscosity average polymerization degree is 300 to 3500 (3) Melting point is higher than vulcanization temperature of belt (4) 20 ° C Solubility in water is 60% by mass or more The friction transmission belt according to claim 1 or 2 , wherein the polyvinyl alcohol resin constituting the polyvinyl alcohol resin particles is a polyvinyl alcohol resin modified with a hydrophobic group. The friction transmission belt according to any one of claims 1 to 3 , wherein the first and second polymer components are ethylene-α-olefin elastomers. The friction transmission belt according to any one of claims 1 to 4 , wherein the compressed rubber layer does not contain a polyvinyl alcohol-based resin. Furthermore, a stretch rubber layer forming a core and a belt back surface is formed, a compression rubber layer is formed on one surface of the stretch rubber layer, and between the stretch rubber layer and the compression rubber layer in the belt longitudinal direction The friction transmission belt according to any one of claims 1 to 5 , wherein the core body is embedded along the belt. Friction transmission belt according to any one of claims 1 to 6, which is a V-ribbed belt. A compression rubber layer winding step of winding an unvulcanized rubber sheet around a cylindrical drum; and a vulcanization molding step of vulcanizing the unvulcanized rubber sheet against a mold, the compression rubber layer winding step and the vulcanization step The method for producing a friction transmission belt according to any one of claims 1 to 7 , wherein the surface layer is formed in any step of the sulfur molding step. In step with the compression rubber layer winding, as the unvulcanized rubber sheet, according to claim 8, wherein a laminated sheet of unvulcanized rubber layer for forming a compression rubber layer and the unvulcanized rubber layer for forming a surface layer Manufacturing method. 9. The production method according to claim 8 , wherein in the compressed rubber layer winding step, a sheet obtained by applying polyvinyl alcohol resin particles to the surface of an unvulcanized rubber sheet for forming a compressed rubber layer is used as the unvulcanized rubber sheet. The manufacturing method according to claim 8 , wherein in the vulcanization molding step, a mold in which polyvinyl alcohol resin particles are applied to a contact surface with an unvulcanized rubber sheet is used as a mold.

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