WO2016068337A1 - Friction transmission belt and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a friction transmission belt used for driving accessories of an automobile engine, etc., and specifically relates to a friction transmission belt which stabilizes the friction condition of a friction transmission surface while maintaining performance of the belt, such as fuel consumption reduction performance and wear-resistance performance, to improve sound-generation-resistance performance, and the manufacturing method thereof. The technical problem to be addressed is to provide a friction transmission belt which stabilizes the friction condition of a friction transmission surface while maintaining performance of the belt, such as the fuel consumption reduction performance and the wear-resistance performance, to improve the sound-generation-resistance performance, and the manufacturing method thereof. In order to solve the technical problem, a compressed layer (2) of the friction transmission belt (10) contains a rubber composition that contains a polymer component and a polyvinyl-alcohol-based resin.

Description

Friction transmission belt and manufacturing method thereof

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. The present invention relates to a friction transmission belt capable of improving the speed and a manufacturing method thereof.

In the rubber industry field, high functionality and high performance are desired especially for automotive 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 coefficient of friction is significantly reduced partially, the friction state becomes unstable, and a stick-slip sound is generated.

Patent Document 1 discloses a friction transmission belt in which at least a 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. Yes. 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, reducing 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. Furthermore, when a surfactant is blended in the entire compressed rubber layer, the mechanical properties (such as strength and elongation) of the compressed rubber layer may be reduced.

In Patent Document 2, in a transmission belt in which a compression rubber layer is disposed on the belt bottom surface side of a core wire, short fibers made of gelable polyvinyl alcohol fibers subjected to RFL treatment are formed on the compression rubber layer. A transmission belt embedded so as to be exposed is disclosed. 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.

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

Furthermore, short fibers are harder to disperse in the compressed rubber layer than particles and have low processability. Furthermore, 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 reduced, and the resorcin-formalin-latex (RFL) treatment is performed to improve the adhesion. Surface treatment such as is necessary. Moreover, since the short fiber is mix | blended with the whole compression rubber layer, there exists a possibility that a mechanical characteristic may fall.

In Patent Document 3, at least a part of the friction transmission surface is composed of a rubber composition containing 5 to 50 parts by mass of a water-soluble polymer having a melting point or softening point of 80 ° C. or less with respect to 100 parts by mass of rubber. A friction transmission belt 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. Moreover, since water-soluble polymer is mix | blended with the whole compression rubber layer, there exists a possibility that a mechanical characteristic may fall. 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.

Patent Document 4 discloses a surface rubber layer that includes a compressed rubber layer that contacts a pulley and transmits power, and that the compressed rubber layer has a relatively high plasticizer content and includes a granular ultrahigh molecular weight polyethylene resin. And a friction transmission belt having an inner rubber layer with a relatively small plasticizer content. Patent Document 5 discloses a friction transmission belt having a compression rubber layer having a friction transmission surface for engaging or contacting with a pulley, and having a lubricant formed of polyethylene resin attached to the friction transmission surface. Has been.

However, polyethylene resins such as ultra-high molecular weight polyethylene resin can improve the sound resistance and wear resistance by reducing the friction coefficient, but cannot suppress the sound generation under water at a high level.

Japanese Unexamined Patent Publication No. 2008-185162 Japanese Unexamined Patent Publication No. 2006-118661 Japanese Unexamined Patent Publication No. 2008-157445 International Publication No. 2011/114727 Japanese Unexamined Patent Publication No. 2013-113343

Accordingly, an object of the present invention is to provide a friction transmission belt capable of improving 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, and a method for manufacturing the same. There is to do.

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 belt performance such as strength and elongation, and a method for manufacturing the same. .

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 the compression layer of the friction transmission belt is formed of a rubber composition containing a polymer component and a polyvinyl alcohol-based resin, fuel economy, wear resistance, etc. 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 is a friction transmission belt including a compression layer having a transmission surface at least partially in contact with the pulley, and the compression layer includes a polymer component and a polyvinyl alcohol resin.

The compression layer preferably has a surface layer containing a polyvinyl alcohol resin on the surface of the transmission surface. Moreover, it is preferable that the said surface layer is formed with the rubber composition containing a polymer component and polyvinyl alcohol-type resin, or is formed with polyvinyl alcohol-type resin. The compressed layer preferably contains a polyvinyl alcohol-based resin only on the surface layer.

The polyvinyl alcohol resin is preferably 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 is preferably about 86 to 97 mol%.

The polyvinyl alcohol-based resin preferably has a viscosity average polymerization degree of about 300 to 3,500.

The melting point of the polyvinyl alcohol resin is preferably higher than the vulcanization temperature of the belt.

The solubility of the polyvinyl alcohol resin in water at 20 ° C. is preferably 60% by mass or more.

The polyvinyl alcohol resin is preferably polyvinyl alcohol resin particles modified with a hydrophobic group.

In the compressed layer, the ratio of the polyvinyl alcohol-based resin is preferably about 5 to 30 parts by mass with respect to 100 parts by mass of the polymer component.

The polyvinyl alcohol resin is preferably dispersedly 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 forming a belt back surface, the compression layer is formed on one surface of the stretch layer, and between the stretch layer and the compression layer. The core body is preferably embedded along the belt longitudinal direction.

The friction transmission belt of the present invention is preferably a V-ribbed belt.

In addition, the manufacturing method of the friction transmission belt of the present invention,
A compression 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,
A surface layer is formed in any one of the compressed layer winding step and the vulcanization molding step.

In the compressed layer winding step, a laminated sheet of an unvulcanized rubber layer for forming a surface layer and an unvulcanized rubber layer for forming a compressed layer is preferably used as the unvulcanized rubber sheet.

In the compressed layer winding step, it is preferable to use, as the unvulcanized rubber sheet, a sheet in which polyvinyl alcohol resin particles are applied to the surface of an unvulcanized rubber sheet for forming a compressed layer.

In the vulcanization molding step, it is preferable to use a mold in which polyvinyl alcohol resin particles are applied to the contact surface with the unvulcanized rubber sheet as the mold.

In the present invention, since the compression layer contains a combination of a polymer component and a polyvinyl alcohol-based resin, belt performance such as fuel saving and wear resistance is maintained (performance does not deteriorate due to inhibition of rubber cross-linking). As it is, the friction state of the friction transmission surface can be stabilized to improve the 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.
In addition, when a surface layer containing polyvinyl alcohol 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 sound resistance (especially sound resistance when wet) Property). In this case, in particular, since the surface layer contains a polyvinyl alcohol-based resin, the polyvinyl alcohol-based resin is appropriately dissolved in water to form a uniform water film on the friction transmission surface while maintaining mechanical properties such as strength and elongation. In addition, sound generation due to slip between the friction transmission surface and the pulley during flooding 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 sectional view showing another example of the V-ribbed belt of the present invention. FIG. 3 is a schematic diagram for explaining a method of measuring a contact angle in the embodiment. FIG. 4 is a schematic diagram for explaining a method of measuring torcross in the embodiment. FIG. 5 is a schematic diagram for explaining a misalignment pronunciation test in the embodiment. FIG. 6 is a graph showing the contact angle with water in the vulcanized rubber sheet obtained in the example. FIG. 7 is a graph showing the relationship between the friction coefficient and the sliding speed of the vulcanized rubber sheet obtained in the example. FIG. 8 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 of the V-ribbed belt is not particularly limited, and for example, the form shown in FIGS. 1 and 2 is exemplified. FIG. 1 is a schematic sectional view showing an example of a friction transmission belt of the present invention. A friction transmission belt 10 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 (in the belt longitudinal direction) from the belt lower surface (inner circumferential surface) to the belt upper surface (back surface). The stretched layer 5 is made of a woven fabric, a knitted fabric, a non-woven fabric, or the like. 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).

FIG. 2 is a schematic sectional view showing another example of the friction transmission belt of the present invention. The friction transmission belt 20 shown in FIG. 2 is different from the friction transmission belt 10 shown in FIG. 1 in that it has a surface layer 6 on the surface of the compression layer 2.

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 a 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.

The core is not particularly limited, but normally, cores (twisted cords) arranged at a predetermined interval 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, usually 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. .

Furthermore, 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 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.

[Compression layer]
The friction transmission belt of the present invention includes a compression layer having a transmission surface at least partially in contact with the pulley, and the compression layer includes a polymer component and a polyvinyl alcohol resin. The compression layer may have a surface layer containing a polyvinyl alcohol resin on the surface. When the compression layer has a surface layer, the polyvinyl alcohol-based resin may be present in the entire compression layer or only in the surface layer. The surface layer may be a surface layer (single layer) formed of a polyvinyl alcohol resin, or a surface layer (composite layer) formed of a rubber composition containing a polyvinyl alcohol resin and a polymer component. The surface layer will be described later.

(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, ethylene-α-olefin elastomers (ethylene-propylene rubber (EPR), ethylene-propylene rubber (EPR), free from harmful halogens, ozone-resistant, heat-resistant, cold-resistant, and economically superior). Ethylene-α-olefin rubbers such as ethylene-propylene-diene copolymers (EPDM, etc.) are preferred.

(Polyvinyl alcohol resin)
In the present invention, by blending a polyvinyl alcohol-based resin with the polymer component, the particles can be dispersed substantially uniformly on the polished friction transmission surface and exposed without protruding. The polyvinyl alcohol resin may be present in the form of particles. The polyvinyl alcohol 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 such as 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.

The polyvinyl alcohol resin only needs to contain a vinyl alcohol unit as a main unit, and may further contain other copolymerizable units in addition to the vinyl alcohol 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. Of 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 with respect to the total units, for example, 0 to 30 mol%, preferably 0.1 to 20 mol%, more preferably 1 to 10 mol. %. 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 in water can be adjusted, and torcross can be suppressed.

The saponification degree of the vinyl alcohol unit of the polyvinyl alcohol resin 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 from the viewpoint that 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 degree of polymerization of the polyvinyl alcohol resin 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 a uniform dispersion state, layer shape, and 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 resin 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. The melting point of the polyvinyl alcohol resin may be, for example, 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 resin is melted by vulcanization, and it may be difficult to uniformly disperse in the polymer component, or it may be difficult to maintain the layer shape.

The solubility of polyvinyl alcohol resin 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, it may be about 60 to 99% by mass), more preferably about 80% by mass or more (for example, 80 to 95% by 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.

When the polyvinyl alcohol resin is in the form of particles, the number average particle diameter of the particles is, for example, about 10 to 300 μm, preferably 15 to 200 μm, and more preferably 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 exposed to water), and drop off of particles during belt running and generation of cracks between particles and rubber. From the viewpoint of suppression, the particle size may be relatively small, for example, about 10 to 100 μm, preferably about 20 to 80 μm, more preferably about 30 to 50 μm (particularly 35 to 45 μm). The reason why small-diameter particles can improve sound resistance is that the uniform dispersion improves the wettability with water and prevents the particles from falling off and cracking between the particles and the rubber during belt running. 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 in the polymer component, which may reduce the sound resistance. 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 diameter of the polyvinyl alcohol-based 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.

When the polyvinyl alcohol-based resin is in the form of particles, the average aspect ratio (ratio of major axis to minor axis) of the particles may be 10 or less (for example, 1 to 10), for example, 1 to 5, preferably 1 to 3, More preferably, it is about 1 to 2 (for example, 1.2 to 1.9). 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 sound resistance when wet. It may be a degree. If the aspect ratio is too large, stress concentration occurs at the interface when the compressed layer is deformed, and the fracture elongation of the compressed layer 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.

When the polyvinyl alcohol-based resin has a particle shape, shearing or tensile stress concentration at the interface between the rubber and the polyvinyl alcohol hardly occurs when the compression layer is deformed. Therefore, the particles can be fixed in the polymer component without performing an adhesion treatment with an adhesion component such as 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 a polymer component forming a compression layer (or surface layer).

The proportion of the polyvinyl alcohol resin (particularly polyvinyl alcohol resin particles) may be about 1 part by mass or more, for example, 1 to 50 parts by mass, preferably 3 to 40 parts by mass with respect to 100 parts by mass of the polymer component. (For example, 5 to 30 parts by mass), more preferably about 5 to 35 parts by mass (particularly 10 to 30 parts by mass). Further, the ratio of the polyvinyl alcohol-based resin particles is preferably large from the viewpoint of improving 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 is too large, the mechanical properties of the compression layer are deteriorated, and if it is too small, the sound resistance may be deteriorated.

(Reinforcing material)
The compression layer may include 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 size carbon black has a small reinforcing effect and poor wear resistance, it is preferable to use a small particle size carbon black (iodine adsorption amount higher than 40 mg / g) having a small particle size 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 between the average particle size of the large particle size carbon black and 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 of 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). C _2-4 alkylene C _6-14 arylate fiber such as naphthalate (PEN) fiber], synthetic fiber such as vinylon fiber, polyparaphenylenebenzobisoxazole (PBO) fiber; natural fiber 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.

Of 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 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 (especially 60 parts by mass). (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 fiber 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 compression layer 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, stearic acid metal salts, waxes, paraffins, etc.), anti-aging agents (aromatic amines, benzimidazole anti-aging agents, etc.), adhesion improvers (resorcin-formaldehyde cocondensates) , Melamine resins such as hexamethoxymethylmelamine, co-condensates thereof (resorcin-melamine-e 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 can form a uniform water film on the frictional 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. Expressed as a ratio to energy, it is a measure of energy loss, that is, tan δ can be expressed numerically as an index by which vibration energy applied to the compressed layer is dissipated as heat. In the preferred embodiment of the present invention, attention is paid to tan δ at a 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 0.0% in order to improve fuel efficiency. The range can be selected from about 8 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 0.13). )

[Surface]
In the friction transmission belt of the present invention, the compression layer may have a surface layer containing a polyvinyl alcohol-based resin on the surface of the transmission surface. The polyvinyl alcohol-based resin is water-soluble, and can exist on the surface of the compression layer as a surface layer to improve wettability (affinity between rubber and water) of the friction transmission surface of the compression layer with respect to water.

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 (entire exposed surface) from the viewpoint of productivity.

The surface layer should just contain the above-mentioned polyvinyl alcohol-type resin, but the surface layer (single layer) formed with the polyvinyl alcohol-type resin and the surface layer (with the rubber composition containing a polyvinyl alcohol-type resin and a polymer component ( It can be roughly divided into a composite layer.

Examples of the polymer component in the composite layer include those described above. In the composite layer, the polyvinyl alcohol resin may be present in the form of particles. When the polyvinyl alcohol resin is present 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 rubber composition in which particles are dispersed in advance, and the latter dispersion form can be easily prepared by partially attaching the particles to the surface of the compression layer. .

In the present invention, since the surface layer includes a polyvinyl alcohol-based resin, the inner layer of the compression layer does not need to include a polyvinyl alcohol-based resin. That is, the compressed layer of the present invention may contain a polyvinyl alcohol resin only in the surface layer. When the inner layer of the compression layer includes a polyvinyl alcohol resin, it is preferable that the polyvinyl alcohol resin is included at a lower concentration than the surface layer from the viewpoint that the mechanical properties of the compression layer can be maintained.

In addition, the surface layer may appropriately contain the above-described reinforcing material, other additives, and compounding agents.

(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, for example, it is about 1 to 500 μm, preferably about 5 to 300 μm, more preferably about 10 to 150 μm. The thickness is 1500 μm, preferably 150 to 800 μm, more preferably about 200 to 600 μm. 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 compression 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 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

[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 mold having a smooth surface, and a core wire (twisted cord, etc.) that forms a core is spirally spun onto the sheet, and further, an adhesive layer sheet, compressed A layered sheet is 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 (only the compression layer is expanded to form a preform (semi-vulcanized state), and then the stretch layer, 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 preferable, 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 is reduced. However, the transmission of the compression layer formed by these methods is reduced. The surface may be polished or ground to expose the polyvinyl alcohol-based resin.

When the compression layer has a surface layer containing a polyvinyl alcohol-based resin, the friction transmission belt manufacturing method includes a compression layer winding step of winding an unvulcanized rubber sheet around a cylindrical drum, and the unvulcanized rubber sheet as a mold. A method including a vulcanization molding step of pressing and vulcanizing can be employed, and a surface layer can be formed in any one of the compression layer winding step and the vulcanization molding step.

Other than the method of forming the surface layer, any conventional method can be used without particular limitation as long as it is a method of forming with a mold. Conventional methods include, for example, a core spinning process for winding a core wire around a cylindrical drum, a compression layer winding step for winding an unvulcanized rubber sheet on the wound core wire, the core wire and the unvulcanized A method including a vulcanization molding process in which a rubber sheet is pressed against a mold (pressed with a mold) and vulcanized can be used. When forming an extension layer or an adhesive layer, as a pre-process of the core spinning process, A step of winding a member constituting a stretch layer (rubber sheet or reinforcing cloth) and a rubber sheet forming an adhesive layer as necessary on a flexible jacket (bladder) mounted on a cylindrical molding drum The core wire may be further spirally spun on the wound member. Specifically, the above-described second manufacturing method and third manufacturing method can be mentioned.

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

In the method (1), the production method of the laminated sheet is not particularly limited, and a conventional method can be used. For example, each unvulcanized sheet produced separately 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 produced with a rubber composition containing a polyvinyl alcohol-based resin, particles partially exposed on the surface and particles completely buried in the layer are mixed and dispersed almost uniformly. A composite layer having the above shape can be easily formed.

In the methods (2) and (3), the polyvinyl alcohol-based resin may be applied or adhered to the resin (resin particles) itself, or a liquid composition in which the resin (resin particles) is dispersed in a solvent. Also good.

Application methods include conventional methods such as coater method, casting method, dipping method, spray method, spinner method and the like. 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 include water, alcohols (for example, alkanols such as ethanol and isopropanol), hydrocarbons (for example, aromatic hydrocarbons such as toluene and xylene), ethers ( For example, chain ethers such as diethyl ether; cyclic ethers such as dioxane and tetrahydrofuran), ketones (for example, chain ketones such as acetone and methyl ethyl ketone; cyclic ketones such as cyclohexanone), esters (for example, acetic acid such as ethyl acetate) Ester), cellosolves (methyl cellosolve, ethyl cellosolve, butyl cellosolve, etc.), and general-purpose solvents such as 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.

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 resin (resin particles) itself can be partially dispersed on the transmission surface. By reducing the solid content concentration of the liquid composition, it is possible to easily form a composite layer having a form in which only resin 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 material of the compression layer used in the Example and the evaluation method of the measured evaluation item are shown below.

[Compression layer material]
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: partially saponified polyvinyl alcohol, degree of saponification of 86.5 to 89.5 mol%, viscosity average polymerization degree of 600, “Denkapoval B-05S” manufactured by Denki Kagaku Kogyo Co., Ltd.
PVA-C: polyvinyl alcohol hydrophobic group-modified product, 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, Denkapoval K-177 manufactured by Denki Kagaku Kogyo 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.
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
Talc: “RL217” manufactured by Fuji Talc Kogyo Co., Ltd., median diameter 20 μm
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.).
Softener (paraffin oil): “Diana Process Oil” manufactured by Idemitsu Kosan Co., Ltd.
Organic peroxide: Dicumyl peroxide.

[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 was 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, giving an initial strain (static strain) of 2.0%, and a frequency of 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. 3, 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 from 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. 3) 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 by measuring r and h from the projected photograph of the dropped water using a fully automatic contact angle meter (“CA-W type” manufactured by Kyowa Interface Science Co., Ltd.), and 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 of the coefficient of friction curve (μ-V characteristic) with respect to the friction speed (sliding speed with respect to the counterpart material) was calculated by the method of least squares. 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. 4, a V-ribbed belt is hung on a two-axis running tester composed of a 55 mm diameter drive (Dr) pulley and a 55 mm diameter driven (Dn) pulley, 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) caused by the bearing from the torque cross (torque resulting from the two of the belt and the bearing) calculated by running the V-ribbed belt 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 resin particles]
Using a scanning electron microscope ("VE-7800" manufactured by Keyence Co., Ltd.), the polyvinyl alcohol resin particles as raw materials were photographed at a magnification of 50 times, and then the particles of the polyvinyl alcohol resin particles were used using image analysis software. The diameter (major axis and minor axis) was measured, and the average particle diameter and aspect ratio of the polyvinyl alcohol resin particles were calculated. The results are shown in Table 1.

[Comparative Examples 1-2 and Examples 1-5]
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 amount of William wear and 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 clear 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.

Further, in Examples 1 to 6, the storage elastic modulus increased as compared with Comparative Example 1 in which a surfactant was blended. 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. 6, 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. 7, Example 4 showed 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.

Further, from comparison between Example 3 and Example 6, in the case of a completely saponified polyvinyl alcohol product, the change in the friction coefficient 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, a belt was produced by the first manufacturing 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.

Further, a vulcanized rubber sheet and a test piece were prepared from the rubber composition collected from the compression layer sheet, and the results of measuring 6% slip wear, belt torque and viscoelasticity (tan δ) are shown in Table 3. Table 3 and FIG. 8 show the results of measuring the belt sounding limit angle.

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

Moreover, the Example had a transmission loss (torcross) smaller than that of Comparative Example 3 in which a surfactant was added, and was equivalent to Comparative Example 4 that did not contain PVA or a surfactant.

Further, as apparent from the results of Table 3 and FIG. 8, 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 sound resistance is high. It was good. It is considered that the hydrophilicity was improved by the blending of PVA and the friction state was stabilized.

As is clear 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 the examples, the larger the amount of PVA, the greater the sounding limit angle when wet, and the sound resistance was excellent.

[Comparative Examples 5 to 8, Examples 16 to 20]
[Preparation of rubber layer]
As a compressed rubber layer and a surface layer, the rubber composition shown in Table 4 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 4 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 4, the rubber compositions B to G containing the PVA resin particles have improved wettability with water and changed the friction coefficient compared to the rubber composition A containing no PVA resin particles. (The slope of the μ-V curve) became smaller.

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

[Comparative Example 5]
The rubber composition A in Table 4 was kneaded with a Banbury mixer, and the kneaded rubber was passed through a calender roll to produce a 2.3 mm thick unvulcanized rolled rubber sheet (compression rubber layer sheet). 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 manufacturing method. That is, the stretch rubber layer sheet and the adhesive rubber layer sheet are sequentially wound around the outer periphery of the mold bladder having the air supply port and the top plate, and the core wire is spirally wound around the outer peripheral surface of the adhesive rubber layer sheet. After that, a sheet for a compressed rubber layer was wound around the core wire, 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 6]
After winding the compressed rubber layer sheet, use a powder coating device to spray talc under the condition of spraying amount of 100 g / m ² , and wind it around the core wire so that the side with talc attached is outside Obtained a V-ribbed belt in the same manner as in Comparative Example 5. 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 7]
A V-ribbed belt was obtained in the same manner as in Comparative Example 6 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 8]
Each of the rubber composition A and the rubber composition H was 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 H 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 5 except that the layer formed of the rubber composition H was wound around the core so that the layer was on the outside.

[Example 16]
A V-ribbed belt was obtained in the same manner as in Comparative Example 8 except that the rubber composition E was used instead of the rubber composition H.

[Example 17]
A V-ribbed belt was obtained in the same manner as in Comparative Example 8 except that the rubber composition F was used instead of the rubber composition H.

[Example 18]
A V-ribbed belt was obtained in the same manner as in Comparative Example 8 except that the rubber composition D was used instead of the rubber composition H.

[Example 19]
A V-ribbed belt was obtained in the same manner as in Comparative Example 8 except that the rubber composition G was used instead of the rubber composition H.

[Example 20]
A V-ribbed belt was obtained in the same manner as in Comparative Example 6 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 5 shows the measurement results of the sounding limit angles of the belts obtained in Comparative Examples 5 to 8 and Examples 16 to 20.

As is apparent from the results in Table 5, Examples 16 to 20 containing polyvinyl alcohol in the surface layer had a higher sounding limit angle when exposed to water and improved sound resistance compared to Comparative Examples 5 to 8.

On the other hand, Comparative Examples 6 to 8 including particles other than polyvinyl alcohol on the surface layer and Comparative Example 5 not including particles have a smaller sounding limit angle when exposed to water than Examples 16 to 20, and sound resistance. Was low.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention.
This application is incorporated in Japanese Patent Application No. 2014-223772 filed on October 31, 2014, Japanese Patent Application No. 2014-262804 filed on December 25, 2014, and Japanese Patent Application No. 2015-208209 filed on October 22, 2015. The contents of which are incorporated herein by reference.

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 6 ... Surface layer

Claims (22)

1. A friction transmission belt including a compression layer having a transmission surface at least partially in contact with the pulley, the compression layer including a polymer component and a polyvinyl alcohol resin.
2. The friction transmission belt according to claim 1, wherein the compression layer has a surface layer containing a polyvinyl alcohol resin on a surface of the transmission surface.
3. The friction transmission belt according to claim 2, wherein the surface layer is formed of a rubber composition containing a polymer component and a polyvinyl alcohol resin.
4. The friction transmission belt according to claim 2, wherein the surface layer is formed of a polyvinyl alcohol-based resin.
5. The friction transmission belt according to any one of claims 2 to 4, wherein the compression layer includes a polyvinyl alcohol-based resin only in a surface layer.
6. The friction transmission belt according to any one of claims 1 to 5, wherein the polyvinyl alcohol resin is polyvinyl alcohol resin particles.
7. The friction transmission belt according to claim 6, wherein the polyvinyl alcohol-based resin particles have an average aspect ratio of 10 or less.
8. The friction transmission belt according to any one of claims 1 to 7, wherein the saponification degree of the vinyl alcohol unit of the polyvinyl alcohol resin is 86 to 97 mol%.
9. The friction transmission belt according to any one of claims 1 to 8, wherein the polyvinyl alcohol-based resin has a viscosity average polymerization degree of 300 to 3,500.
10. The friction transmission belt according to any one of claims 1 to 9, wherein the melting point of the polyvinyl alcohol resin is higher than a vulcanization temperature of the belt.
11. The friction transmission belt according to any one of claims 1 to 10, wherein the polyvinyl alcohol resin has a solubility in water at 20 ° C of 60% by mass or more.
12. The friction transmission belt according to any one of claims 1 to 11, wherein the polyvinyl alcohol resin is polyvinyl alcohol resin particles modified with a hydrophobic group.
13. 13. The friction transmission belt according to claim 1, wherein a ratio of the polyvinyl alcohol resin in the compressed layer is 5 to 30 parts by mass with respect to 100 parts by mass of the polymer component.
14. The friction transmission belt according to any one of claims 1 to 13, wherein the polyvinyl alcohol-based resin is dispersedly exposed on the transmission surface.
15. The friction transmission belt according to any one of claims 1 to 14, wherein the compression layer further includes a reinforcing material.
16. The friction transmission belt according to any one of claims 1 to 15, wherein the polymer component is an ethylene-α-olefin elastomer.
17. And further comprising a core and a stretch layer forming a belt back surface, wherein the compression layer is formed on one surface of the stretch layer, and the core along the longitudinal direction of the belt between the stretch layer and the compression layer. The friction transmission belt according to any one of claims 1 to 16, wherein the body is embedded.
18. The friction transmission belt according to any one of claims 1 to 17, which is a V-ribbed belt.
19. A compression 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 method for producing a friction transmission belt according to any one of claims 2 to 5, wherein a surface layer is formed in any one of the compression layer winding step and the vulcanization molding step.
20. 20. In the compressed layer winding step, a laminated sheet of an unvulcanized rubber layer for forming a surface layer and an unvulcanized rubber layer for forming a compressed layer is used as the unvulcanized rubber sheet. Manufacturing method.
21. The manufacturing method according to claim 19, wherein in the compressed layer winding step, a sheet obtained by applying a polyvinyl alcohol-based resin to the surface of an unvulcanized rubber sheet for forming a compressed layer is used as the unvulcanized rubber sheet.
22. The manufacturing method according to claim 19, wherein in the vulcanization molding step, a mold in which a polyvinyl alcohol resin is applied to a contact surface with an unvulcanized rubber sheet is used as a mold.
    
    

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