JP2021055836A - Friction transmission belt - Google Patents

Abstract

To provide a friction transmission belt capable of improving sounding resistance while maintaining transmission efficiency and durability.SOLUTION: A superficial layer 6 containing a hardened rubber composition including polyvinylpyrrolidone resin and an elastomer component is laminated on top of a friction transmission surface. The superficial layer 6 may be made of the hardened rubber composition including polyvinylpyrrolidone resin and the elastomer component. Also, the superficial layer 6 may additionally include a fabric. The elastomer component may include ethylene-α-olefine elastomer. The rubber composition to form the superficial layer does not preferably include binder resin. The rubber composition to form a compressed rubber layer does not preferably include polyvinylpyrrolidone resin. The friction transmission belt may be a V-ribbed belt or a low-edge V-belt.SELECTED DRAWING: Figure 1

Description

The present invention relates to a friction transmission belt (particularly, a V-ribbed belt) used for driving an automobile engine auxiliary machine or the like. Specifically, the present invention stabilizes the friction state of the friction transmission surface while maintaining transmission ability and fuel efficiency, and is sound resistant. Regarding friction transmission belts that can improve fuel efficiency.

In the rubber industry, high functionality and high performance are desired especially in 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 automobile air compressor and an alternator, for example. As a belt of this type, a V-ribbed belt in which ribs are provided along the longitudinal direction of the belt is known, but the V-ribbed belt is required to have sound resistance in addition to belt performance such as transmission ability and fuel efficiency. Will be done.

Regarding sound resistance in auxiliary drive systems such as automobile engines, the friction coefficient of the belt surface (pulley engaging surface) in contact with the pulley is reduced to reduce the noise that tends to occur when the pulley is misaligned (axis misalignment) and the stick. -Improving noise due to the slip phenomenon is an issue.

The stick-slip phenomenon is a self-excited vibration caused by the adhesion of microscopic friction surfaces between friction surfaces and repeated sliding, and when the coefficient of friction decreases as the sliding speed increases, or from static friction. It occurs when discontinuous friction reduction occurs when shifting to dynamic friction. Even in a friction transmission belt, if the friction coefficient of the transmission surface that rubs against the pulley is high (especially high adhesiveness), a stick that repeats adhesion (stick) and slip (slip) between the friction between the belt and the pulley. -A slip phenomenon (vibration) occurs, and an abnormal noise (squeal) occurs at the stage of transition from adhesion to slip.

Furthermore, the generation of stick-slip noise during running under water is also a problem. Specifically, if the wettability of the friction transmission surface is low and the water infiltration state between the belt and pulley is not uniform, the friction coefficient is high in the place where water does not infiltrate (dry state), and the water infiltrate part (covered). In the water state), the coefficient of friction is partially significantly reduced, the friction state becomes unstable, and a stick-slip sound is generated.

So far, from the viewpoint of forming a surface layer on the friction transmission surface for improving the sound resistance, a belt that improves the sound resistance when exposed to water (reduces abnormal noise due to stick-slip) has been proposed.

Japanese Unexamined Patent Publication No. 2011-190916 (Patent Document 1) discloses a friction transmission belt in which a surface rubber layer having a relatively large content of a plasticizer is formed on the surface of the compressed rubber layer.

Further, Japanese Patent Application Laid-Open No. 2016-121806 (Patent Document 2) discloses a friction transmission belt in which a surface layer formed of a rubber composition containing polyvinyl alcohol-based resin particles and a polymer component is laminated on the surface of the transmission surface. ing.

Further, Japanese Patent Application Laid-Open No. 2017-150662 (Patent Document 3) discloses a friction transmission belt in which a friction transmission surface is coated with a surface layer containing a hydrophilic resin such as a polyvinyl alcohol resin and a binder resin.

Japanese Unexamined Patent Publication No. 2011-190916 Japanese Unexamined Patent Publication No. 2016-121806 JP-A-2017-150662

In Patent Documents 1 to 3, the sound resistance when exposed to water can be improved by incorporating a sound resistance improving agent in the surface layer. Further, by including the sound resistance improving agent only in the surface layer, it is possible to suppress the transmission loss (torcross) caused by the energy loss (tan δ) due to the internal heat generation.

Further, in the friction transmission belt containing the plasticizer of Patent Document 1, the affinity between the rubber (ethylene-α-olefin elastomer) forming the friction transmission surface and water is enhanced by the plasticizer exuded on the friction transmission surface. It is possible to stabilize the frictional state between the belt and the pulley and improve the sound resistance when exposed to water (reduce abnormal noise due to stick-slip).

However, on the other hand, since the plasticizer lacks heat resistance, it easily disappears from the friction transmission surface during traveling, and a long-lasting effect cannot be expected.

Further, the polyvinyl alcohol-based resins of Patent Documents 2 and 3 have a large particle size, so that the crack resistance is lowered.

Therefore, an object of the present invention is to provide a friction transmission belt capable of improving sound resistance while maintaining transmission efficiency and durability.

As a result of diligent studies to achieve the above problems, the present inventors have found that at least a part of the friction transmission surface has a friction transmission surface that can come into contact with the pulley, and friction including a compressed rubber layer formed of a cured product of the rubber composition. In the transmission belt, by laminating a surface layer containing a cured product of a rubber composition containing a polyvinylpyrrolidone resin and an elastomer component on the surface of the friction transmission surface, sound resistance is maintained while maintaining transmission efficiency and durability. We have found that it can be improved and completed the present invention.

That is, the friction transmission belt of the present invention is a friction transmission belt that has at least a part of the friction transmission surface that can come into contact with the pulley and includes a compressed rubber layer formed of a cured product of the rubber composition. A surface layer containing a cured product of a rubber composition containing a polyvinylpyrrolidone-based resin and an elastomer component is laminated on the surface of the friction transmission surface. The surface layer may be formed of a cured product of the rubber composition containing the polyvinylpyrrolidone-based resin and the elastomer component. Further, the surface layer may be a layer further containing a cloth. The elastomer component may include an ethylene-α-olefin elastomer. The K value of the polyvinylpyrrolidone-based resin may be 10 to 100. The ratio of the polyvinylpyrrolidone-based resin may be 1 to 20 parts by mass with respect to 100 parts by mass of the elastomer component. The rubber composition for forming the surface layer preferably does not contain a binder resin. The rubber composition for forming the compressed rubber layer does not have to contain a polyvinylpyrrolidone-based resin. The friction transmission belt may be a V-ribbed belt or a low-edge V-belt.

In the present invention, in a friction transmission belt having a friction transmission surface at least partially in contact with a pulley and containing a compression rubber layer formed of a cured product of a rubber composition, polyvinyl is applied to the surface of the friction transmission surface. Since the surface layer containing the cured product of the rubber composition containing the pyrrolidone resin and the elastomer component is laminated, it is possible to improve the sound resistance while maintaining the belt performance such as the transmission efficiency and durability of the friction transmission belt.

FIG. 1 is a schematic cross-sectional view showing an example of the friction transmission belt of the present invention. FIG. 2 is a graph showing the behavior of Mooney viscosity for explaining a method for measuring Mooney scorch minimum viscosity (Vm). FIG. 3 is a schematic diagram showing the layout of the belt misalignment sounding test obtained in Examples 1 to 9, Comparative Examples 1 to 4 and 8. FIG. 4 is a schematic diagram showing a layout of a running test for performing a post-running misalignment sounding test of the belts obtained in Examples 1 to 9 and Comparative Examples 1 to 4 and 8. FIG. 5 is a schematic view showing the layout of the water injection resistance sounding test of the belts obtained in Examples 10 to 17 and Comparative Examples 5 to 7. FIG. 6 is a schematic view showing a layout of a running test for performing a water injection resistance sound resistance test after running of the belts obtained in Examples 10 to 17 and Comparative Examples 5 to 7. FIG. 7 is a schematic view showing the layout of the transmission performance test of the belts obtained in the examples and the comparative examples. FIG. 8 is a schematic view showing the layout of the endurance running test of the belts obtained in the examples and the comparative examples. FIG. 9 is a schematic view showing the layout of a biaxial running test for measuring the transmission loss of the V-ribbed belt obtained in Examples and Comparative Examples.

[surface]
The friction transmission belt of the present invention contains a compressed rubber layer having a friction transmission surface at least partially in contact with the pulley, and a cured product of a rubber composition containing a polyvinylpyrrolidone resin and an elastomer component on the surface of the friction transmission surface. The surface layer containing is laminated. The friction transmission surface can come into contact with the pulley via the surface layer. This surface layer exhibits the above-mentioned effects by containing a combination of a polyvinylpyrrolidone-based resin and an elastomer component. Although the details of the mechanism by which the effect is exhibited are unknown, it can be estimated as follows when analyzed ex post facto.

First, the sound when water is received is that when water enters between the belt and the pulley, the coefficient of friction remains high at the point where water does not enter (dry state) on the contact surface with the pulley. This is caused by the fact that the coefficient of friction is significantly reduced only at the place where the water has infiltrated (water-covered state), that is, the dry state and the water-covered state are mixed on the contact surface with the pulley. Conventionally, this phenomenon has been measured by measuring the relationship (μ-V characteristic) between the slip speed (V) and the friction coefficient (μ) during running under water, and the friction coefficient decreases as the slip speed increases. In some cases, a stick-slip sound is produced.

Therefore, among those skilled in the art, as sound resistance, aiming to prevent the contact surface with the pulley from being mixed with the dry state and the water-submerged state even when the pulley is in contact with the pulley. A method of increasing hydrophilicity to improve wettability (making the whole wet) is used. By putting the entire contact surface in a water-covered state, the friction state of the surface is stabilized, and in the μ-V characteristics (the slope of the friction coefficient-slip speed curve, the change in the friction coefficient μ with respect to the slip speed V when water is in contact). The purpose is to suppress the sounding because the friction coefficient does not decrease even if the sliding speed is increased. Based on this idea, conventional sound resistance improvers (plasticizers, surfactants, water-soluble polymers, etc.) increase the hydrophilicity of the entire contact surface with the pulley to make it wet (the whole is wet). It can be said that it is a formulation for reducing the change in the friction coefficient μ with respect to the change in the sliding speed by improving the above.

For example, in the case of a liquid plasticizer, it bleeds from the inside of the rubber layer to the contact surface with the pulley, and when it is exposed to water, a uniform water film is formed on the entire contact surface, and friction occurs even if the sliding speed increases. The decrease in coefficient μ is suppressed, and the effect of improving pronunciation resistance can be obtained. However, this state has the following drawbacks (1) to (3).

(1) Grip force decreases as the friction coefficient μ itself decreases, and transmission performance decreases (slip loss increases). (2) Since it is a liquid, it is affected by supply and dissipation to the contact surface, so it is on the contact surface. The sustainability of the function is limited. (3) Addition of a plasticizer or a surfactant causes a decrease in the physical characteristics (elastic modulus) of rubber and an increase in internal heat generation (increase in torque cloth).

On the other hand, in the case of a solid water-soluble polymer, it exists as particles on the contact surface, and when it is exposed to water and gradually dissolves, a uniform water film is formed. Therefore, the above-mentioned drawbacks such as plasticizers do not occur.

However, among solid water-soluble polymers, polyvinyl alcohol (PVA) -based resin has a large particle size, so when used for a long period of time, the eluted PVA portion becomes dents and defects occur, or it becomes a rubber layer. It has the disadvantage that cracks are likely to occur from the interface with the PVA particles.

On the other hand, the polyvinylpyrrolidone (PVP) -based resin has a smaller particle size than PVA, so that the crack resistance can be further improved. Therefore, in the present invention, by using the PVP-based resin, the above-mentioned effect, that is, in detail, the following effects (1) to (5) can be exhibited.

(1) Sound resistance when exposed to water (the coefficient of friction does not easily decrease even if the sliding speed increases)
(2) Persistence of pronunciation resistance effect (effect lasts for a long time)
(3) High grip, that is, high transmission performance can be maintained (less slip loss)
(4) The physical properties (elastic modulus) of rubber do not decrease and the internal heat generation does not increase (increase in torque cloth). (5) Excellent crack resistance and long durable life.

The surface layer may be laminated on the friction 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 and the like.

(Elastomer component)
The rubber composition for forming the surface layer (curable rubber composition) contains an elastomer component. As the elastomer component, vulverable or crosslinkable rubber may be used, for example, diene rubber [natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (nitrile rubber). , Hydrogenated nitrile rubber, etc.], ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluororubber, etc. .. These elastomer components can be used alone or in combination of two or more. Of these, ethylene-α-olefin elastomers are preferable because they are excellent in ozone resistance, heat resistance, cold resistance, and weather resistance, and the weight of the belt can be reduced.

The ethylene-α-olefin elastomer may contain an ethylene unit and an α-olefin unit as a constituent unit, and may further contain a diene unit. Therefore, the ethylene-α-olefin elastomer includes ethylene-α-olefin copolymer rubber, ethylene-α-olefin-diene ternary copolymer rubber and the like.

Examples of the α-olefin for forming an α-olefin unit include chain α-C _3-12 olefins such as propylene, butene, pentene, methylpentene, hexene, and octene. Of these α-olefins, α-C _3-4 olefins such as propylene (particularly propylene) are preferable.

As the diene monomer for forming a diene unit, a non-conjugated diene-based monomer is usually used. Examples of the non-conjugated diene-based monomer include dicyclopentadiene, methylenenorbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene and the like. Of these diene monomers, etylidene norbornene and 1,4-hexadiene (particularly etylidene norbornene) are preferable.

Typical ethylene-α-olefin elastomers include, for example, ethylene-propylene copolymer (EPM) and ethylene-propylene-diene ternary copolymer (EPDM).

These ethylene-α-olefin elastomers can be used alone or in combination of two or more. Of these, ethylene-α-olefin-diene ternary copolymer rubber is preferable, and ethylene-propylene-diene copolymer (EPDM) is particularly preferable, because the cross-linking efficiency by the diene unit is excellent.

In the ethylene-propylene-diene ternary copolymer, the ratio (mass ratio) of ethylene to propylene is 35/65 to 90/10 of the former / the latter, preferably 40/60 to 80/20, and more preferably 45. It may be / 55 to 70/30, most preferably 50/50 to 60/40.

The diene content of an ethylene-α-olefin elastomer (particularly, an ethylene-α-olefin-diene ternary copolymer rubber such as EPDM) may be 10% by mass or less (for example, 0.1 to 10% by mass). It is preferably 7% by mass or less (for example, 0.3 to 7% by mass), more preferably 5% by mass or less (for example, 0.5 to 5% by mass), and most preferably 3% by mass or less (for example, 1 to 3% by mass). Is. In the present invention, the heat resistance is improved by using an elastomer component that does not have a double bond in the main chain, but it is highly advanced by suppressing the double bond due to the diene unit introduced as the side chain to a small amount. Heat resistance can be guaranteed. If the diene content is too high, high heat resistance may not be guaranteed.

In the present application, the diene content means the mass ratio of the diene monomer unit in all the units constituting the ethylene-α-olefin elastomer, and can be measured by a conventional method, but may be a monomer ratio.

The Mooney viscosity [ML (1 + 4) 125 ° C.] of the unvulcanized ethylene-α-olefin elastomer may be 80 or less, and the Vm of the rubber composition can be adjusted to improve the dispersibility of carbon black. For example, it is 10 to 80, preferably 20 to 70, more preferably 30 to 50, and most preferably 35 to 45. If the Mooney viscosity is too high, the fluidity of the rubber composition may decrease, and the processability in kneading may decrease.

In the present application, the Mooney viscosity can be measured by a method according to JIS K 6300-1 (2013), and the test conditions are an L-shaped rotor, a test temperature of 125 ° C., a preheating of 1 minute, and a rotor operating time of 4 minutes. Is.

The proportion of the ethylene-α-olefin elastomer in the elastomer component may be 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and most preferably 100% by mass (ethylene-α-). Olefin elastomer only). If the proportion of ethylene-α-olefin elastomer in the elastomer component is too small, heat resistance and cold resistance may decrease.

(Polyvinylpyrrolidone resin)
The rubber composition further contains a polyvinylpyrrolidone (PVP) -based resin in addition to the elastomer component.

The PVP-based resin may contain N-vinyl-2-pyrrolidone units as the main constituent units, and may further contain other copolymerizable units.

Examples of the monomer for forming other copolymerizable units include olefins (such as α-C _2-10 olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexene) and unsaturated carboxylic acids. _{Acids [(meth) acrylic acid C 1-6} alkyl esters such as (meth) acrylic acid, methyl (meth) acrylic acid, ethyl (meth) acrylic acid, (anhydrous) maleic acid, etc.], fatty acid vinyl esters (vinyl acetate) , Vinyl propionate, vinyl crotonate, etc.), Vinyl ethers (C _1-6 alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, 1,4-butanediol Examples _{thereof include C 2-6} alkanediol-vinyl ether such as vinyl ether) and unsaturated sulfonic acids (ethylene sulfonic acid, allyl sulfonic acid, etc.). These monomers can be used alone or in combination of two or more. Of these, unsaturated carboxylic acids such as (meth) acrylic acid and methyl (meth) acrylate, and fatty acid vinyl esters such as vinyl acetate are preferable.

In the PVP-based resin, the ratio of N-vinyl-2-pyrrolidone units is, for example, 50% by mass or more (for example, 70 to 98% by mass), preferably 80% by mass or more (for example, 80 to 95% by mass), and further. It is preferably 90% by mass or more, and most preferably 100% by mass.

The PVP-based resin may be a conventional modified product or derivative. Further, the form of the PVP-based resin may be linear or branched.

The K value of the PVP resin is not particularly limited, but from the viewpoint of improving the durability and sound resistance of the belt, for example, 10 to 100, preferably 15 to 99, more preferably 17 to 98, and more preferably 20 to 20 to 100. 97, most preferably 22.5 to 96. If the K value is too small, the durability and power transmission of the belt may decrease, and if it is too large, the sound resistance may decrease.

In the present application, the K value is a viscosity characteristic value that correlates with the molecular weight, and can be calculated by applying the relative viscosity value (25 ° C.) measured by a capillary viscometer to the following Fikenscher equation.

_{K = (1.5logη rel -1) /} (0.15 + 0.003c) + [300clogη rel + (c + 1.5clogη rel) 2] 1/2 /(0.15c+0.003c 2)
[In the formula, η _rel : relative viscosity of the PVP-based resin aqueous solution with respect to water, cc: PVP-based resin concentration (mass%) in the PVP-based resin aqueous solution]

The ratio of the PVP-based resin can be selected from the range of about 0.1 to 25 parts by mass with respect to 100 parts by mass of the elastomer component, for example, 0.1 to 20 parts by mass, preferably 0.5 to 15 parts by mass, more preferably. Is 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and most preferably 3 to 7 parts by mass. In particular, from the viewpoint of achieving both belt performance such as high transmission efficiency and sound resistance, the ratio of the PVP-based resin is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass with respect to 100 parts by mass of the elastomer component. It is by mass, more preferably 3 to 10 parts by mass. If the proportion of the PVP resin is too small, the sound resistance when exposed to water may decrease, and if it is too large, the mechanical strength of the surface layer may decrease.

(Crosslinking agent)
The rubber composition may further contain a conventional cross-linking agent (or vulcanizing agent) in addition to the elastomer component and the PVP-based resin. When the elastomer component is an ethylene-α-olefin elastomer, the cross-linking agent may be an organic peroxide or a sulfur-based vulcanizing agent.

Examples of the organic peroxide include diacyl peroxide (dilauroyl peroxide, dibenzoyl peroxide, etc.), peroxyketal [1,1-di (t-butylperoxy) cyclohexane, 2,2-di (t). -Butyl peroxy) butane, etc.], alkyl peroxy ester (t-butyl peroxybenzoate, etc.), dialkyl peroxide [di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, 2,5 -Dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexin-3,1,1-di (t-butylperoxy) ) -3,3,5-trimethylcyclohexane, 1,3-bis (2-t-butylperoxyisopropyl) benzene, 2,5-di-methyl-2,5-di (benzoylperoxy) hexane, etc.], Peroxycarbonate (t-butylperoxyisopropyl carbonate, t-butylperoxy-2-ethyl-hexyl carbonate, t-amylperoxy-2-ethyl-hexyl carbonate, etc.) and the like can be mentioned. These organic peroxides can be used alone or in combination of two or more. Of these, dialkyl peroxides such as 1,3-bis (2-t-butylperoxyisopropyl) benzene are preferable.

Examples of the sulfur-based sulfurizing agent include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and sulfur chloride (sulfur monochloride, sulfur dichloride, etc.).

These cross-linking agents can be used alone or in combination of two or more. Of these, a cross-linking agent containing an organic peroxide is preferable.

The ratio of the vulcanizing agent or the cross-linking agent (particularly, the organic peroxide) is, for example, 0.1 to 30 parts by mass, preferably 1 to 20 parts by mass, and more preferably 3 to 10 parts by mass with respect to 100 parts by mass of the elastomer component. It is by mass, most preferably 4 to 6 parts by mass.

(Reinforcing agent)
The composition may further contain a reinforcing agent in addition to the elastomeric component and the PVP-based resin. Examples of the reinforcing agent include carbon black, silica, clay, calcium carbonate, talc, mica, short fibers and the like. These reinforcing agents can be used alone or in combination of two or more. Of these, carbon black and silica are preferable, and carbon black is particularly preferable.

The ratio of the reinforcing agent is, for example, 10 to 200 parts by mass, preferably 20 to 150 parts by mass, more preferably 30 to 100 parts by mass, and most preferably 50 to 80 parts by mass with respect to 100 parts by mass of the elastomer component.

(Other ingredients)
The rubber composition may further contain a conventional additive used as a rubber compounding agent. Conventional additives include, for example, co-crosslinking agents (such as bismaleimides), vulcanization aids or vulcanization accelerators (such as thiuram-based accelerators), vulcanization retarders, and metal oxides (zinc oxide, magnesium oxide). , Calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), softeners (such as paraffin oil and oils such as naphthenic oil), processing agents or processing aids (stearic acid, stearic acid, etc.) Metal salts, waxes, paraffins, fatty acid amides, etc.), silane coupling agents, anti-aging agents (antioxidants, heat anti-aging agents, bending crack inhibitors, ozone deterioration inhibitors, etc.), coloring agents, tackifiers, Examples include stabilizers (ultraviolet absorbers, heat stabilizers, etc.), flame retardants, antistatic agents, and the like. These additives can be used alone or in combination of two or more. The metal oxide may act as a cross-linking agent.

The total ratio of the conventional additives is, for example, 5 to 50 parts by mass, preferably 10 to 30 parts by mass, and more preferably 15 to 25 parts by mass with respect to 100 parts by mass of the elastomer component.

The rubber composition for forming the surface layer preferably contains substantially no binder resin, and particularly preferably does not contain a binder resin. The binder resin may be, for example, at least one thermoplastic resin selected from the group consisting of polyolefins, styrene resins, polyester resins, polycarbonate resins, polyamide resins and polyurethane resins. In particular, the binder resin may be a polyolefin such as polyethylene or polypropylene.

(Surface structure)
The surface layer may have a single structure (homogeneous structure formed by the cured rubber composition alone) formed of the cured product (cured rubber composition) of the rubber composition, and may be a cloth in addition to the cured rubber composition. It may be a composite structure further containing (a composite structure containing a cured rubber composition and a cloth). As the surface layer structure, a single structure is preferable for applications that require high transmission efficiency (fuel efficiency), and a composite structure is preferable for applications that require high sound resistance.

(Surface layer with composite structure)
When the surface layer has a composite structure, the composite structure consists of a rubber layer formed of a cured rubber composition laminated on the compressed rubber layer and a cured rubber composition laminated on the rubber layer and on the cloth. It may have a two-layer structure of a permeated rubber fiber mixed layer (the outermost surface layer formed of the cloth and the rubber composition permeated between the fibers constituting the cloth). In the surface layer having such a two-layer structure, in the rubber fiber mixed layer on the surface side of the surface layer, the rubber composition permeates (penetrates) into the structure of the fabric (between the fibers) and between the fibers. The fabric is firmly fixed or bonded with. Therefore, the rubber composition permeated between the fibers of the fabric exhibits the effect of the combination of the polyvinylpyrrolidone-based resin and the elastomer component, as in the surface layer having a single structure. Further, in the surface layer having such a two-layer structure, not only the sound resistance but also the abrasion resistance of the fabric can be improved, and as a result, the effect (pronunciation resistance) of the surface layer can be maintained for a long period of time. That is, probably because the rubber composition penetrates between the fibers of the fabric (knitted fabric, etc.) and holds (or binds to) the fibers of the fabric to firmly fix or bond the fabric, or the fabric (knitted fabric, etc.). ) Fibers are suppressed from falling off from the friction transmission surface, and it can be inferred that the wear resistance is improved.

In the surface layer having the two-layer structure, the rubber composition permeates substantially evenly into the structure of the fabric constituting the rubber fiber mixed layer, and the rubber composition is formed on the surface of the rubber fiber mixed layer from the viewpoint of improving the sound resistance. It is preferable that the material does not exude substantially, the rubber composition permeates evenly into the structure of the fabric constituting the rubber fiber mixed layer, and the rubber composition does not exude on the surface of the rubber fiber mixed layer. Is particularly preferable. That is, it is preferable that a layer formed by the cured rubber composition alone (a thin-walled layer formed of the exuded rubber composition) is not substantially formed on the surface of the rubber fiber mixed layer, and the thin-walled layer is formed. It is particularly preferable that it is not formed.

In the surface layer having the two-layer structure, the average thickness of the rubber fiber mixed layer is, for example, 0.25 to 4 times, preferably 0.5 to 2 times, more preferably 0.8 times, the average thickness of the rubber layer. ~ 1.2 times.

(Fabric)
In the surface layer having a composite structure, a woven fabric (woven fabric), a knitted fabric (knitted fabric), a non-woven fabric, or other fiber members can be used as the fabric (fabric layer), and a knitted fabric (or sail cloth) is often used. The knitted fabric is formed of water-absorbent fibers (or hydrophilic fibers) and non-water-absorbent fibers because it can be formed of water-absorbent fibers and / or non-water-absorbent fibers and can improve sound resistance when exposed to water. It may be a knitted fabric (for example, the knitted fabric described in Japanese Patent Application Laid-Open No. 2016-70494).

Examples of the water-absorbent fiber or the hydrophilic fiber (or the fiber containing the water-absorbent yarn) include vinyl alcohol-based fiber (polyvinyl alcohol, ethylene-vinyl alcohol copolymer fiber, vinylon, etc.) and polyamide fiber (polyamide 6 fiber, Polyamide 66 fiber, aliphatic polyamide fiber such as polyamide 46 fiber), cellulose fiber [cellulose fiber (cellulose fiber derived from plants such as cotton and hemp, animals or bacteria), fiber of cellulose derivative such as rayon and acetate] , Animal-derived fibers (wool, silk, etc.). These water-absorbent fibers can be used alone or in combination of two or more. Of these water-absorbent fibers, cellulose fibers (particularly cotton fibers) are preferable.

The cellulosic fiber may be a spun yarn. The thickness (count) of the cellulosic fiber is, for example, 5 to 100 counts, preferably 10 to 80 counts, and more preferably 20 to 70 counts (particularly 30 to 50 counts). If the thickness is too small, the mechanical properties of the knitted fabric may deteriorate, and if it is too large, the water absorption may decrease. A preferred cellulosic fiber is a cellulosic fiber.

Examples of the non-water-absorbent fiber include polyolefin fiber (polyethylene fiber (including high-strength polyethylene fiber), polypropylene fiber, etc.), non-water-absorbent polyamide fiber (aromatic polyamide fiber such as aramid fiber, etc.), acrylic fiber, polyester fiber. polyethylene terephthalate (PET) fibers, polypropylene terephthalate (PPT) fibers, polytrimethylene terephthalate (PTT) fibers, polybutylene terephthalate (PBT) fibers, _{C 2-4} alkylene _{C 6-14,} such as polyethylene naphthalate (PEN) fibers Arilate-based fibers, polyarylate-based fibers, etc.], polyparaphenylene benzobisoxazole (PBO) fibers, synthetic fibers such as polyurethane fibers; inorganic fibers such as carbon fibers can be mentioned. These non-absorbent fibers can be used alone or in combination of two or more. Among these non-water-absorbent fibers, composite fibers (composite yarns), for example, composite fibers of synthetic fibers (composite yarns of synthetic fibers) may be used to improve the wear resistance of the knitted fabric and to transmit friction. In order to prevent rubber from seeping out onto the surface (or the surface of the knitted fabric), bulky processed yarns or bulky composite yarns (such as polyester composite yarns such as PTT / PET conjugate yarns) with a large cross-sectional bulk are used. preferable.

The fineness of the non-water-absorbent fiber may be, for example, about 20 to 600 dtex, preferably 50 to 300 dtex, and more preferably 60 to 200 dtex (particularly 70 to 100 dtex).

The fabric (knitted fabric or the like) preferably contains at least water-absorbent fibers (particularly cellulosic fibers). The ratio of the non-water-absorbent fiber may be selected from the range of, for example, 200 parts by mass or less (for example, 0 to 200 parts by mass) with respect to 100 parts by mass of the water-absorbent fiber, for example, 1 to 100 parts by mass, preferably 3. It may be about 80 parts by mass (for example, 5 to 50 parts by mass), more preferably 10 to 40 parts by mass (particularly 20 to 30 parts by mass). If the proportion of non-water-absorbent fibers is too large, the water absorption of the knitted fabric may decrease, and the sound resistance when exposed to water may decrease.

The structure of the knitted fabric is not particularly limited, and a conventional structure can be used. Single-layer weft knitting [for example, weft knitting with a flat knitting (Tenjiku knitting) as the knitting structure], multi-layer knitting fabric [for example, Kanoko knitting (for example, Kanoko knitting) Weft knitting with Kanoko knitting as the knitting structure)] is preferable, and multi-layer knitted fabric is particularly preferable. In the multi-layer knitted fabric, the number of layers of the knitted fabric may be, for example, 2 to 5, preferably 2 to 4 layers, and more preferably 2 or 3 layers.

The density of fibers or threads of the knitted fabric is, for example, 30 fibers / inch or more (for example, 32 to 70 fibers / inch, preferably 34 to 60 fibers / inch, more preferably 35 to 35) in the wale direction and the course direction, respectively. 55 lines / inch) may be used. Further, the total number may be 60 lines / inch or more (for example, 62 to 120 lines / inch, preferably 70 to 115 lines / inch, more preferably 80 to 110 lines / inch, particularly 90 to 105 lines / inch). ..

Further, the bulkiness range of the fabric or the fiber member (for example, a knitted fabric in which a composite yarn such as a bulky processed yarn as a synthetic fiber is knitted) can be selected within a range in which the exudation of rubber can be suppressed, for example, 2 to 4.5 cm ³ / G (eg 2.2-4 cm ³ / g), preferably 2.3-3.8 cm ³ / g (eg 2.4-3.5 cm ³ / g), more preferably 2.5-3.3 cm ^It may be about 3 / g. The bulkiness (cm ³ / g) can be calculated by dividing the thickness (cm) of the knitted fabric by the mass (g / cm ^{2) per unit area.}

The basis weight of the fabric (knitted fabric or the like) may be, for example, 50 to 500 g / m ² , preferably 80 to 400 g / m ² , and more preferably about 100 to 350 g / m ^2.

The thickness (average thickness) of the fabric (knitted fabric, etc.) can be selected from the range of about 0.1 to 5 mm, for example, 0.3 to 3 mm (for example, 0.4 to 2 mm), preferably 0.5 to 1.5 mm (preferably 0.5 to 1.5 mm). In particular, it may be about 0.7 to 1.2 mm).

In order to improve the adhesiveness to the friction transmission surface, the fabric (knitted fabric or the like) may be subjected to an adhesive treatment, if necessary. The adhesive treatment can also improve the wear resistance of the friction transmission surface (power transmission surface). The adhesive treatment includes, for example, a method in which an adhesive component [for example, an epoxy compound or an isocyanate compound] is immersed in a treatment liquid dissolved in an organic solvent (toluene, xylene, methyl ethyl ketone, etc.) and then heat-dried; resorcin-formalin-latex. Examples thereof include a method of immersing in a liquid (RFL treatment liquid) and then heating and drying. These methods can be performed alone or in combination, and the processing order and the number of processings are not limited. For example, it may be pretreated with an epoxy compound and / or an isocyanate compound, immersed in an RFL treatment liquid, and then heat-dried.

(Isocyanate compound)
When the fabric is treated (impregnated or adhered) with at least an isocyanate compound (polyisocyanate compound), the adhesiveness to the rubber composition and the abrasion resistance of the fabric are improved, and the sound resistance can be maintained for a long period of time. .. In particular, the rubber component on the surface layer and / or the fibers of the fabric (water-absorbent or hydrophilic fibers such as cellulose-based fibers) are active hydrogen atoms such as reactive functional groups (for example, hydroxyl groups, carboxyl groups, amino groups, etc.) with respect to isocyanate compounds. By treating the fabric with an isocyanate compound, the mechanical properties of the fabric itself, the adhesiveness with the rubber component, the abrasion resistance and the durability of the friction transmission belt can be further improved. , Sound resistance can be maintained for a long period of time. The fabric may be treated with an isocyanate compound in combination with resorcin-formalin-latex liquid (RFL liquid) and / or epoxy resin, which are widely used as canvas treatment agents, but the RFL liquid and / or epoxy resin may be used. The adhesiveness and mechanical properties can be improved without treatment.

The isocyanate compound may have a reactive isocyanate group, and usually, a polyisocyanate having a plurality of isocyanate groups in one molecule (for example, diisocyanate) is often used. Examples of the polyisocyanate include aliphatic polyisocyanates [diisocyanates such as propylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMDI), and lysine diisocyanate (LDI); 1,6 , 11-Undecan triisocyanate Methyl octane, tri or polyisocyanate such as 1,3,6-hexamethylene triisocyanate], alicyclic polyisocyanate [cyclohexane 1,4-diisocyanate, isophorone diisocyanate (IPDI), hydrogenated xylylene Diisocyanates such as isocyanates and hydrogenated bis (isocyanatophenyl) methane; tri- or polyisocyanates such as bicycloheptane triisocyanates], aromatic polyisocyanates [phenylenediocyanates, tolylene diisocyanates (TDI), xylylene diisocyanates (XDI), Diisocyanates such as tetramethylxylylene diisocyanate (TMXDI), naphthalenediocyanate (NDI), bis (isocyanatophenyl) methane (MDI), toluidine diisocyanate (TODI), 1,3-bis (isocyanatophenyl) propane; tri or poly Isocyanate] and the like.

Polyisocyanates include derivatives such as multimers (dimers, trimers, tetramers, etc.), adducts, modified products (biuret modified products, alohanate modified products, urea modified products, etc.), and multiple isocyanate groups. It may be a urethane oligomer or the like. Examples of the modified or derivative of polyisocyanate include an adduct of polyisocyanate (such as aliphatic polyisocyanate such as hexamethylene diisocyanate) and polyhydric alcohol (such as trimethylolpropane and pentaerythritol), and a biuret of the polyisocyanate. , A multimer of the polyisocyanate (for example, an aliphatic polyisocyanate) (for example, a polyisocyanate having an isocyanurate ring such as a trimer of hexamethylene diisocyanate) and the like can be exemplified.

These isocyanate compounds can be used alone or in combination of two or more. Among these isocyanate compounds (particularly polyisocyanates), aliphatic polyisocyanates or derivatives thereof (for example, HDI or its trimer), aromatic polyisocyanates (TDI, MDI, etc.) and the like are widely used.

Further, the isocyanate compound may be a general-purpose isocyanate compound having a free isocyanate group (isocyanate compound not protected by a blocking agent), but a heat-reactive isocyanate compound (or an isocyanate compound in which the isocyanate group is protected by a blocking agent). Blocked polyisocyanate) is preferably used. When a heat-reactive isocyanate compound is used, the isocyanate group is protected by a blocking agent in the process of forming the belt, so that it is inactive and does not participate in curing, so that the elasticity (formability) of the fabric is not impaired. In the vulcanization process of the belt, the blocking agent is dissociated, the isocyanate group is activated and reacts with the reactive group of the fabric to harden, and the abrasion resistance can be improved. Therefore, when a heat-reactive isocyanate compound is used, the adhesiveness of the fabric, the abrasion resistance and the durability of the friction transmission belt can be improved without lowering the productivity of the belt, and the sound resistance when exposed to water can be extended for a long period of time. Sustainable throughout. Further, the aqueous immersion liquid containing the isocyanate compound is easier to prepare and has a smaller environmental load than the RFL liquid.

As the heat-reactive isocyanate compound, a conventional heat-reaction type polyisocyanate can be used. Examples of the blocking agent (protective agent) include C _1-24 monoalcohols such as methanol, ethanol and isopropanol or alkylene oxide adducts thereof (for example, C _2-4 alkylene oxide adducts such as ethylene oxide); phenol. , Phenols such as cresol and resorcin; oximes such as acetoxime, methylethylketooxime and cyclohexaneoxime; lactams such as ε-caprolactam and valerolactam; secondary amines such as dibutylamine and ethyleneimine. These blocking agents can be used alone or in combination of two or more. Of these, oximes and lactams are widely used. The form of the heat-reactive isocyanate compound is not particularly limited, and may be in the form of a liquid or powder, and may be in the form of an aqueous solution or an organic solvent (an aqueous solution or a dispersion, an organic solvent solution, etc.). May be good.

The content of the isocyanate group of the isocyanate compound (heat-reactive isocyanate compound, etc.) is not particularly limited, and is, for example, 1 to 50% by mass, preferably 3 to 40% by mass, and more preferably about 5 to 30% by mass. May be good.

The dissociation temperature of the heat-reactive isocyanate compound (the temperature at which the blocking agent dissociates and the active isocyanate group regenerates) is equal to or higher than the heating temperature in the belt forming step before the vulcanization step of the rubber component (usually, the liquid composition by immersion). It may be above the drying temperature of the cloth impregnated with the substance) and below the vulcanization temperature of the rubber component. When the dissociation temperature is high, the drying temperature can be raised, so that the productivity can be improved. The dissociation temperature may be, for example, 120 ° C. or higher (preferably 150 ° C. or higher, more preferably 180 ° C. or higher), for example 120 to 250 ° C. (for example, 150 to 240 ° C.), preferably 160 to 230 ° C. (for example). 170 to 220 ° C.), more preferably about 175 to 210 ° C. (particularly 180 to 200 ° C.). If the dissociation temperature is too low, the drying temperature cannot be raised, so that drying takes time and productivity may decrease.

The present form of the isocyanate compound may be any form in which at least a part of the fibers forming the fabric is coated or adhered. The distribution region of the isocyanate compound may be either the surface of the fabric or the fibers inside the fabric, but in order to improve the abrasion resistance, the fibers inside the fabric (entangled porous structure) are also distributed. It is preferable that the fabric is distributed substantially uniformly (particularly uniformly) over the entire fabric including the fabric. By immersing the cloth in the liquid composition containing the isocyanate compound, the isocyanate compound can be easily and uniformly distributed over the entire cloth.

The proportion of the isocyanate compound may be about 1 to 30% by mass in the fabric, and while maintaining the flexibility of the fabric, the adhesiveness and abrasion resistance are enhanced to improve the sound resistance when exposed to water for a long period of time. From the viewpoint of sustainability, it may be, for example, about 3 to 20% by mass, preferably about 5 to 18% by mass (for example, 7 to 15% by mass), and more preferably about 10 to 15% by mass (for example, 11 to 13% by mass). .. If the proportion of the isocyanate compound is too small, the adhesiveness and abrasion resistance are not improved so much, and the sound resistance when exposed to water may be lowered. On the contrary, if the proportion of the isocyanate compound is too large, the flexibility of the fabric or the belt is lowered. There is a risk.

The fabric (knitted fabric, etc.) contains conventional additives such as a surfactant, a dispersant, a filler, a colorant, a stabilizer, a surface treatment agent, and a leveling agent on the fiber surface or inside the fiber. May be good. These additives can also be used alone or in combination of two or more. The ratio of the additive is 10% by mass or less, for example, 0.01 to 5% by mass, preferably 0.1 to 3% by mass, and more preferably 0.5 to 2% by mass with respect to the entire fabric (knitted fabric, etc.). It may be about. The treated amount (content) of the surfactant may be about 0.1 to 200 g (for example, 1 to 150 g), preferably about 3 to 100 g (for example, 5 to 60 g) per ^{1 m 2 of the cloth.}

(Characteristics of surface layer)
The rubber composition contained in the surface layer is a rubber composition having a Mooney Scorch minimum viscosity Vm adjusted to a range of 50 to 110 (a rubber composition having a Vm adjusted to a predetermined range when measured at a temperature of 125 ° C.). It may be formed. Specifically, the Vm can be selected from the range of 50 to 130 (for example, 55 to 120), and may be, for example, 57 to 115 (for example, 60 to 110), preferably about 65 to 100. In particular, when the surface layer has a composite structure, when the surface layer contains such a rubber composition, the inside of the structure of the fabric (fibers and fibers) to the extent that the rubber composition does not completely permeate the fabric (does not exude to the surface). By penetrating into the space) and firmly fixing or binding the fabric, the effect (sound resistance) of the surface layer can be maintained for a long period of time. Further, by arranging the rubber composition containing the polyvinylpyrrolidone-based resin evenly in the structure of the fabric (between the fibers) on the friction transmission surface, the sound resistance when exposed to water can be maintained. ..

In the case of a surface layer having a composite structure, if the Vm of the rubber composition is too high, the fluidity of the rubber composition is lowered, the permeability to the fabric is lowered, the above effect is lowered, and the surface layer is molded. There is a risk that the sex will deteriorate. If Vm is too low, the fluidity of the rubber composition is high, so that the rubber composition permeates the structure of the fabric (knitted fabric, etc.) and easily exudes to the friction transmission surface, and is sound resistant (adhesion of exuded rubber). (Pronunciation due to wear) There is a risk that the property will deteriorate.

In the present application, the Mooneys coach minimum viscosity Vm can be measured according to the Mooneys coach test of JIS K6300-1 (2013), and in detail, it can be measured by the method described in Examples described later.

The cured product (crosslinked product) of the rubber composition has a low internal loss tangent (tan δ), for example, 0.08 to 0.17, preferably 0.09 to 0.165, and more preferably 0.1 to 0. It is .16, more preferably 0.11 to 0.15, and most preferably 0.12 to 0.15. If tan δ is too high, internal heat generation becomes large, and energy loss (transmission loss) may increase.

In the present application, the loss tangent (tan δ) can be measured by the method described in Examples described later, and the loss tangent in the direction perpendicular to the rolling direction (reverse tangent direction) is measured. Further, in the cured product in which the short fibers are arranged in a predetermined direction, the loss tangent in the direction perpendicular to the arrangement direction (columnar direction) of the short fibers (reverse columnar direction) is measured.

The thickness (average thickness) of the surface layer having a single structure is, for example, 100 to 1500 μm, preferably 150 to 800 μm, and more preferably about 200 to 600 μm. The thickness (average thickness) of the surface layer having a single structure can be selected from the range of about 1 to 50% with respect to the average thickness of the entire compressed rubber layer (average thickness at the apex of the rib portion), for example, 2 to 40%. It is preferably about 3 to 35% (for example, 4 to 30%), more preferably about 5 to 25% (particularly 10 to 20%). If the thickness of the surface layer is too thin, the effect of improving the pronunciation resistance may be reduced, and the durability of the 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 deteriorate.

The thickness (average thickness) of the surface layer having the composite structure is, for example, 150 to 1500 μm, preferably 200 to 1000 μm, and more preferably about 300 to 700 μm. The thickness (average thickness) of the surface layer having the composite structure can be selected from the range of about 1 to 50% with respect to the average thickness of the entire compressed rubber layer (average thickness at the apex of the rib portion), and is preferably 5 to 45%, for example. Is about 10 to 40% (for example, 15 to 35%), more preferably about 20 to 30% (particularly 22 to 28%). If the thickness of the surface layer is too thin, the effect of improving the pronunciation resistance may be reduced, and the durability of the 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 deteriorate.

In the present application, the average thickness of the surface layer is measured by observing the cross section of the compressed rubber layer portion of the friction transmission belt using a scanning electron microscope, and the average value of 10 points is calculated for the surface layer containing the PVP-based resin. Demanded by.

[Compressed rubber layer]
The compressed rubber layer is formed of a rubber composition containing an elastomer component. As the elastomer component, the elastomer component exemplified in the section of the surface layer can be used, and the preferable elastomer component is the same as that of the surface layer. From the viewpoint of interlayer adhesion, the same polymer component as the elastomer component constituting the surface layer is preferable.

The rubber composition for forming the compressed rubber layer may contain a PVP-based resin, but from the viewpoint of physical properties and economic efficiency of the compressed rubber layer, it is preferable that the rubber composition does not substantially contain the PVP-based resin, and PVP. It is preferable that it does not contain a system resin. In the present invention, the above effect can be exhibited by including the PVP-based resin in the rubber composition for forming the surface layer.

The rubber composition for forming the compressed rubber layer may further contain the cross-linking agent, the reinforcing agent, and other components exemplified in the section of the surface layer in addition to the elastomer component, and the preferred embodiment and ratio are also the same as that of the surface layer. The same applies, and the rubber composition may be the same as that of the surface layer except that it does not contain a PVP-based resin.

The minimum viscosity Vm of the Mooney scorch of the rubber composition forming the compressed rubber layer is not particularly limited, but is preferably Vm or more of the rubber composition contained in the surface layer from the viewpoint of improving the durability of the belt. The Vm of the rubber composition forming the compressed rubber layer may be, for example, about 50 to 150, preferably 70 to 130, more preferably 80 to 120, and even more preferably 90 to 110 (particularly 95 to 105). The difference between the two Vm is that the Vm of the rubber composition contained in the surface layer is, for example, 0 to 40, preferably 0 to 30, and more preferably 0 to 25 lower than the Vm of the rubber composition forming the compressed rubber layer. It may be. When adjusted to such a viscosity, in the case of a surface layer having a composite structure, the Vm of the compressed rubber layer is increased to increase the strength of the belt, and the Vm of the surface layer (rubber completely penetrates the fabric). Can be lowered (to the extent that it is not). Therefore, in the case of a surface layer having a composite structure, the rubber composition can easily penetrate into the structure of the fabric without lowering the durability of the belt, and the adhesive force between the fabric and the rubber component and the abrasion resistance of the fabric can be easily obtained. You can improve your sex. If the Vm of the rubber composition is too low, the belt strength may decrease, and conversely, if it is too high, the rib shape may be defective.

[Structure of friction transmission belt]
The friction transmission belt of the present invention usually includes an extension layer, a compression rubber layer laminated on one surface of the extension layer, a surface layer laminated on the transmission surface of the compression rubber layer, and the extension layer and the compression. It is provided with a core body (core wire) embedded along the longitudinal direction of the belt between the rubber layer and the rubber layer. Specifically, the friction transmission belt of the present invention has an extension layer forming an outer peripheral surface, a compression rubber layer laminated on one surface of the extension layer to form an inner peripheral surface, and a transmission surface of the compression rubber layer. A laminated surface layer and a core body extending in the longitudinal direction and interposing between the stretched layer and the compressed rubber layer may be provided. Further, 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 rubber layer, and the core body is embedded in the adhesive rubber layer. You may.

The type of friction transmission belt is not particularly limited, and V-belts [low-edge belts (low-edge belts in the form of a V-shaped cross section) and low-edge cogged belts (cogs are formed 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 can be exemplified. Among these belts, V-ribbed belts and low-edge V-belts having high transmission efficiency are preferable, and V-ribbed belts are particularly preferable.

The form of the V-ribbed belt is not particularly limited, and for example, the form shown in FIG. 1 is exemplified. FIG. 1 is a schematic cross-sectional view showing an example of the friction transmission belt of the present invention. In this embodiment, the V-ribbed belt 1 has 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 longitudinal direction of the belt, in this order from the lower surface (inner peripheral surface) of the belt to the upper surface (back surface) of the belt. It has a form in which an extension layer 2 composed of a cover canvas (woven fabric, knitted fabric, non-woven fabric, etc.) is laminated. The compression rubber layer 5 is formed with a plurality of V-shaped grooves extending in the longitudinal direction of the belt, and a plurality of ribs having a V-shaped cross section (inverted trapezoidal shape) are formed between the grooves. The two inclined surfaces (surfaces) form a friction transmission surface, which is in contact with the pulley to transmit power (friction transmission).

The friction transmission belt of the present invention is not limited to this form, and may include an stretch layer, a compressed rubber layer, and a core body embedded along the longitudinal direction of the belt between them. For example, the stretch layer 2 is stretched. It may be formed of a conventional cover canvas or a rubber composition used as a layer, or the core body 4 may be embedded between the stretch 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 stretchable layer 2, and the core body 4 is provided between the adhesive rubber layer 3 (compressed rubber layer 5 side) and the stretchable layer 2, or the adhesive rubber layer 3. It may be embedded between (extension layer 2 side) and the compression rubber layer 5. Further, the surface of the surface layer 6 (particularly, the friction transmission surface) may be in the form of flocked powder fibers (for example, cotton, nylon, aramid, etc.), or may be spray-coated with a lubricant or the like.

It is sufficient that at least the surface layer contains the rubber composition and the compressed rubber layer is formed of the rubber composition, and the adhesive rubber layer is not formed of the rubber composition of the surface layer and the compressed rubber layer. May be good. The rubber composition forming the adhesive rubber layer is usually formed of the rubber composition forming the compressed rubber layer. When the stretch layer is formed of a rubber composition, the stretch layer may be formed of a rubber composition that forms a compressed rubber layer.

The core body is not particularly limited, but usually, core wires (twisted cords) arranged at predetermined intervals in the belt width direction can be used. Highly modulus fibers such as polyester fibers (polyalkylene allylate fibers), synthetic fibers such as aramid fibers, and inorganic fibers such as carbon fibers are widely used as core wires, and polyester fibers (polyester terephthalate fibers, polyethylene naphthalate) are used. Fibers) and aramid fibers are preferable. The fiber may be a multifilament yarn, for example, a multifilament yarn having a fineness of about 2000 to 10000 denier (particularly 4000 to 8000 denier).

As the core wire, a twisted cord using a multifilament yarn (for example, various twists, single twist, rung twist, etc.) can be usually used. The average wire diameter of the core wire (fiber diameter of the twisted cord) may be, for example, 0.5 to 3 mm, preferably 0.6 to 2 mm, and more preferably about 0.7 to 1.5 mm. The core wires are arranged so as to extend in the longitudinal direction of the belt, and a plurality of core wires parallel to the longitudinal direction may be arranged, but from the viewpoint of productivity, they are usually arranged substantially parallel to the longitudinal direction of the belt. It extends in parallel at a predetermined pitch and is arranged in a spiral shape. When arranged in a spiral shape, the angle of the core line with respect to the longitudinal direction of the belt may be, for example, 5 ° or less, and is preferably closer to 0 ° from the viewpoint of belt travelability.

In order to improve the adhesiveness with the elastomer component, the core wire is embedded between the stretchable layer and the compressed rubber layer (particularly the adhesive rubber layer) after undergoing various adhesive treatments with an epoxy compound, an isocyanate compound, or the like. May be good.

Further, the stretch layer may have a reinforcing cloth, for example, a cloth material (preferably a woven cloth) such as a woven cloth, a wide-angle canvas, a knitted cloth, or a non-woven fabric. If necessary, the reinforcing cloth may be subjected to the above-mentioned adhesive treatment and laminated on the surface of the stretchable layer.

[Belt manufacturing method]
The friction transmission belt is manufactured by a compression rubber layer winding step of winding an unvulcanized (unbridged) rubber sheet around a cylindrical drum, and a vulcanization molding step of pressing the unvulcanized rubber sheet against a mold to vulcanize. A method including the above can be adopted, and the surface layer is formed by any of the steps of the compression rubber layer winding step and the vulcanization molding step.

Except for the method of forming the surface layer, the method is not particularly limited 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 wire spinning step of winding a core wire forming a core body on a cylindrical drum, a compression rubber layer winding step of winding an unvulcanized rubber sheet on the wound core wire, and the core. A method can be used that includes a vulcanization molding step of pressing the wire and the unvulcanized rubber sheet against a mold (pressing with a mold) to vulcanize, and if a stretch layer or an adhesive rubber layer is to be formed, a core wire. As a pre-process of the spinning process, a member constituting an extension layer (rubber sheet or reinforcing cloth) and, if necessary, an adhesive rubber layer are formed on a flexible jacket (bladder) mounted on a cylindrical molded drum. The step of winding the rubber sheet to be wound 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 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 flexible jacket on the outer peripheral surface. The core wire forming the core is spirally spun on the sheet, and the unvulcanized compressed rubber layer sheet is wound around the sheet to prepare a laminated body. Next, as the outer mold that can be attached to the inner mold, a tubular outer mold having a plurality of rib molds engraved on the inner peripheral surface is used, and the inner mold in which the laminated body is wound is formed in the outer mold. , Install concentrically. Then, the flexible jacket is expanded toward the inner peripheral surface (rib mold) of the outer mold, and the laminate (compressed rubber layer) is press-fitted into the rib mold and vulcanized. Then, the inner mold is removed from the outer mold, the vulcanized (crosslinked) rubber sleeve having a plurality of ribs is removed from the outer mold, and then the vulcanized rubber sleeve is cut to a predetermined width in the longitudinal direction of the belt using a cutter. And finish it as a V-ribbed belt. In this method, the laminate provided with the stretch layer, the core body, and the compressed rubber layer can be expanded at once to finish a sleeve (or V-ribbed belt) having a plurality of ribs.

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 obtain a preformed body (semi-vulcanized state), and then the stretch layer and the core body are expanded. A method of crimping the preformed body to the preformed body and integrating it with vulcanization to finish the V-ribbed belt) may be adopted.

The method of forming the surface layer can be incorporated into either the compression rubber layer winding step or the vulcanization molding step in such a conventional method. For example, in the compression rubber layer winding step, unvulcanized. As a rubber sheet, a laminated sheet of a precursor (unvulcanized rubber sheet (rubber composition) or cloth and rubber composition) for forming a surface layer and an unvulcanized rubber sheet for forming a compressed rubber layer is provided. Examples include the method used. In this method, the method for preparing the laminated sheet is not particularly limited, and a conventional method can be used. When the surface layer has a single structure, for example, each unvulcanized rubber sheet separately produced by rolling or the like is used. It may be laminated, or it may be a laminated sheet formed by coextrusion. When the surface layer has a composite structure, the unvulcanized rubber sheet and the cloth are sequentially wound and laminated on the unvulcanized rubber sheet for forming the compressed rubber layer as a precursor for forming the surface layer. May be good. In particular, in the surface layer having a composite structure, the cloth is arranged on the outermost surface, and in the process of manufacturing the belt, a part of the unvulcanized rubber sheet is permeated into the entire cloth to be formed by the rubber layer and the rubber fiber mixed layer. The surface layer may be manufactured.

The method for preparing the rubber composition for forming the surface layer and the compressed rubber layer can be prepared by mixing (or kneading) each component by a conventional method, but in order to mix uniformly, an elastomer component and a PVP system can be prepared. It is preferable to knead the resin or the like under heating. The heating temperature is, for example, 120 ° C. or lower, preferably 50 to 120 ° C., more preferably 60 to 100 ° C., still more preferably 70 to 90 ° C. If the heating temperature is too high, the elastomeric components may crosslink.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The details of the raw materials used in the examples are shown below.

[material]
(Rubber composition)
EPDM1: "Nordel® IP3640" manufactured by The Dow Chemical Company, Mooney viscosity (125 ° C.) ≈40, ethylene content 55% by mass, diene content 1.8% by mass
EPDM2: "EPT4045M" manufactured by Mitsui Chemicals, Inc., Mooney viscosity (125 ° C) ≈45, ethylene content 51% by mass, diene content 7.6% by mass
Polyvinylpyrrolidone 1: "Polyvinylpyrrolidone K-30" manufactured by Nippon Shokubai Co., Ltd., K value 27.0 to 33.0
Polyvinylpyrrolidone 2: "Polyvinylpyrrolidone K-90" manufactured by Nippon Shokubai Co., Ltd., K value 88.0-96.0
Polyvinylpyrrolidone 3: "Polyvinylpyrrolidone K-25" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., K value 22.5 to 27.0
Polypropylene: "PPW-5" manufactured by Seishin Enterprise Co., Ltd., average particle size of about 5 μm, melting point of 165 ° C.
Surfactant: "Emargen LS-106" manufactured by Kao Co., Ltd., Polyoxyalkylene alkyl ether Polyvinyl alcohol: "Dencapovar F-300S" manufactured by Electrochemical Industry Co., Ltd., Polyvinyl alcohol hydrophobic group modified product, degree of polymerization 93 .0-97.0 mol, viscosity average degree of polymerization 1700, melting point 206 ° C, type of hydrophobic group: alkyl group Carbon black: "Seast 3" manufactured by Tokai Carbon Co., Ltd.
Silica: "Ultrasil VN3" manufactured by Evonik Industries AG, BET specific surface area 180m ² / g
Paraffin oil: "Diana (registered trademark) PW-90" manufactured by Idemitsu Kosan Co., Ltd. (paraffin-based process oil)
Zinc oxide: "2 types of zinc oxide" manufactured by HakusuiTech Co., Ltd.
Stearic acid: "Tsubaki stearic acid" manufactured by NOF CORPORATION
Anti-aging agent 1: Benzimidazole-based anti-aging agent, "Nocrack MB" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Anti-aging agent 2: Diphenylamine-based anti-aging agent, "Nocrack AD-F" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Co-crosslinking agent: "Barnock PM" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Organic peroxide: "Perbutyl P-40MB" manufactured by NOF CORPORATION
Sulfur: Made by Bigen Kagaku Co., Ltd. Vulcanization accelerator: Made by Ouchi Shinko Kagaku Kogyo Co., Ltd. "Noxeller (registered trademark) DM"
Carbon black dispersion: "Aqua-Black162" manufactured by Tokai Carbon Co., Ltd. Solid content 19.2% by mass

(Cotton woven cloth)
Plain weave fabric with 20s / 2 cotton threads, 70 warp threads / 5 cm, and 70 weft threads / 5 cm

(Knitted cloth for surface layer)
A cotton spun yarn (40 count, 1 yarn) as a water-absorbent fiber and a PPT / PET conjugated yarn (fineness 84 dtex) as a second fiber are knitted, and the knitting structure is weft knitting (Kanoko, 2 layers). The knitted fabric base material is a heat-reactive isocyanate (“Elastron BN-27” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., an aqueous isocyanate-based cross-linking agent having a dissociation temperature of 180 ° C. and a solid content concentration of 30% by mass) and a solid content concentration of 5 mass. A treated knitted fabric that has been soaked in an aqueous solution diluted with water and then dried.

(Core line)
Plyed cord with a total denier 6,000 cord made by twisting 1,000 denier PET fibers in a 2 x 3 twist configuration with an upper twist coefficient of 3.0 and a lower twist coefficient of 3.0, and a core wire diameter. 1.0 mm.

Examples 1-17 and Comparative Examples 1-8
[Surface layer and compressed rubber layer]
For the surface layer and the compressed rubber layer forming the transmission surface (contact surface with the pulley) of the belt, the surface layer and the rubber composition for the compressed rubber layer having the formulation shown in Table 1 are kneaded at 140 ° C. using a Banbury mixer, and a calendar is used. A sheet rolled to a predetermined thickness with a roll was used. The thickness of the surface layer sheet was adjusted so that the thickness of the surface layer was 500 μm. In Comparative Examples 1 and 5, the surface layer was not formed, and in Comparative Example 8, the surface layer described later was formed.

[Characteristics of crosslinked rubber of composition for surface layer and compressed rubber layer]
The uncrosslinked (unvulcanized) rubber sheet for the surface layer and the compressed rubber layer was pressurized and heated for 30 minutes (temperature 180 ° C., surface pressure 0.9 MPa) using a press to prepare a crosslinked rubber sheet.

1) Measurement of μ-V characteristics A disk-shaped test piece having a diameter of 8 mm and a thickness of 2 mm was collected from a crosslinked rubber sheet, and the friction force was measured using a pin-on-disk friction coefficient measuring device to calculate the friction coefficient. .. Specifically, the test piece is pressed against a mating material (SUS304) having a surface roughness Ra of 0.8 μm at a load of 2.192 kgf / cm ² , and the test piece is sprinkled with water only when measuring at a water volume of 30 ml / min. However, the frictional force was measured at a frictional speed of 0 to 2.0 m / sec, and the slope of the curve of the friction coefficient with respect to the frictional speed (sliding speed with respect to the mating material) was calculated by the minimum square method. In addition, this inclination represents the change of the friction coefficient with respect to the slip speed.

Furthermore, the accelerated aging test according to JIS K 6257 (2010) was performed, and the frictional force was measured for the test piece after heat aging at 150 ° C. for 720 hours, and the frictional velocity (slip against the mating material) was measured. The slope of the curve of the friction coefficient with respect to velocity) was calculated by the method of least squares.

As the pin-on-disc friction coefficient measuring device, a "pin-on-disc friction tester" manufactured by Yonekura Seisakusho Co., Ltd. was used. In the accelerated aging test, the A method AA-2 forced circulation type heat aging tester (crosswind type) was used.

2) Measurement of dynamic viscoelasticity (E', tanδ) A test piece having a rectangular cross-sectional shape (thickness 2.0 mm, width 4.0 mm) and a length of 40 mm was collected from the crosslinked rubber sheet. At this time, the direction of rolling reversal was taken as the length direction. Then, the test piece is chucked and fixed to the chuck of the viscoelasticity measuring device (“VR-7121” manufactured by Ueshima Seisakusho) at a distance between the chucks of 15 mm, an initial strain (static strain) of 1.0% is given, and the frequency is 10 Hz. , Dynamic strain 0.2% (that is, while applying ± 0.2% strain in the longitudinal direction with the initial strain 1.0% as the center position or the reference position), 70 at a heating rate of 1 ° C./min. The elastic modulus (E') and loss tangent (tan δ) at ° C. were determined.

3) Mooney scorch minimum viscosity (Vm)
The minimum viscosity of Mooney scorch was measured according to the Mooney scorch test of JIS K6300-1 (2013). The rotor was L-shaped and the test temperature was 125 ° C. A polyester film having a thickness of about 0.04 mm (“Lumilar” manufactured by Toray Industries, Inc.) was placed between the surfaces of the test piece (uncrosslinked rubber composition) and the die. After closing the die, it was preheated for 1 minute, after which the rotor was rotated and the transition of Mooney viscosity was recorded. The recorded Mooney viscosity generally showed the behavior as shown in FIG. 2, and the value when the Mooney viscosity became the lowest was adopted as the Mooney Scorch minimum viscosity (Vm).

[Adhesive rubber layer]
The adhesive rubber layer sheet was obtained by kneading the adhesive rubber layer rubber composition having the composition shown in Table 2 using a Banbury mixer and rolling it to a predetermined thickness with a calendar roll.

[Extended layer]
For the cotton woven fabric for forming the stretch layer, untreated cotton woven fabric (plain weave of cotton yarn 20s / 2, warp yarn 70 yarns / 5 cm, weft yarn 70 yarns / 5 cm) is used as a carbon black dispersion liquid and an RFL liquid (latex). , Resolsin and formalin), soaked in the stretch layer composition (black dyeing solution) shown in Table 3 for 10 seconds, treated with a tenter at a wide angle of 120 °, and heat-treated at 150 ° C for 4 minutes. There was.

[Manufacturing of V-ribbed belt]
In Examples 1 to 9 and Comparative Examples 1 to 4, a cotton woven cloth and a sheet for an adhesive rubber layer for forming an stretch layer are sequentially wrapped around the outer periphery of a mold bladder provided with an air supply port and a top plate. After spirally winding the core wire as the core around the outer peripheral surface of the adhesive rubber layer sheet, the compressed rubber layer sheet and the surface layer sheet are sequentially wound on the core body (Comparative Example 1 is for the surface layer). A non-crosslinked belt sleeve was formed (without wrapping the sheet).

In Examples 10 to 17 and Comparative Examples 5 to 7, for a cotton woven fabric and an adhesive rubber layer for forming an stretch layer on the outer periphery of a bladder of a mold (inner mold) provided with an air supply port and a top plate. The sheets are wound in sequence, and the core wire to be the core is spirally wound around the outer peripheral surface of the adhesive rubber layer sheet, and then the compressed rubber layer sheet, the surface layer sheet, and the surface layer knitted fabric are further wound on the core body. The uncrosslinked belt sleeve was formed by sequentially winding (Comparative Example 5 did not wind the surface layer sheet). The obtained surface layer has a two-layer structure consisting of a rubber layer and a rubber fiber mixed layer in which the rubber composition has penetrated into the knitted fabric, and the average thickness ratio of both layers is rubber layer / rubber fiber mixed layer = 1/1. Met.

In Comparative Example 8, a cotton woven cloth for forming an extension layer and a sheet for an adhesive rubber layer are sequentially wound around the outer periphery of a bladder of a mold (inner mold) provided with an air supply port and a top plate, and the adhesive rubber layer is formed. After spirally winding the core wire as the core body on the outer peripheral surface of the sheet, the sheet for the compressed rubber layer was further wound on the core body. Using a powder coating device (“Angkor XT Hand Gun” manufactured by Nordon Co., Ltd.) on the friction transmission surface of the belt sleeve, polyvinylpyrrolidone 1 and polypropylene were applied under the condition of ^{a spray rate of 50 g / m 2, the former: the latter = 25:75.} The mixed powder blended in the mass ratio of was sprayed to form an uncrosslinked belt sleeve.

Further, the mold (inner mold) around which the uncrosslinked belt sleeve is wound by each method is set in the vulcanization mold (outer mold), and while heating with a heating / cooling jacket equipped with a heating / cooling medium introduction port. , The bladder was expanded, and the uncrosslinked belt sleeve was pressed against the inner peripheral surface of the vulcanization mold to pressurize the vulcanization. The vulcanization conditions were set at 180 ° C., 0.9 MPa, and 30 minutes. At this time, a groove (rib shape) was formed on the outer circumference of the belt sleeve by the vulcanization type uneven portion for molding biting into the belt sleeve from the outer circumference.

Next, the mold was taken out from the vulcanization mold, the crosslinked belt sleeve remaining in the vulcanization mold was cooled by the heating / cooling jacket, and then the crosslinked belt sleeve was taken out from the vulcanization mold. Then, by cutting this crosslinked belt sleeve so as to cut it into round slices with a cutter, a 3PK1100 V-ribbed belt (number of ribs: 3, circumference: 1100 mm, belt type: K type, belt thickness: 4.3 mm, rib height). : Approximately 2 mm, rib pitch: 3.56 mm), 6PK980 V-ribbed belt (number of ribs: 6, circumference: 980 mm, belt type: K type, belt thickness: 4.3 mm, rib height: approximately 2 mm, rib pitch: 3 .56 mm), 6 PK1100 V-ribbed belt (number of ribs: 6, circumference: 1100 mm, belt type: K type, belt thickness: 4.3 mm, rib height: about 2 mm, rib pitch: 3.56 mm) was obtained. The 6PK980 V-ribbed belt was manufactured only in Examples 10 to 17 and Comparative Examples 5 to 7.

[Performance evaluation of V-ribbed belt]
1) Pronunciation limit angle test (misalignment pronunciation evaluation test)
The pronunciation limit angle test (misalignment pronunciation evaluation test) includes a drive pulley (Dr.) with a diameter of 101 mm, an idler pulley (IDL1) with a diameter of 70 mm, a misalignment pulley (W / P) with a diameter of 120 mm, and an idler pulley with a diameter of 70 mm (Dr.). 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 using a testing machine having a layout 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, the 6PK1100 V-ribbed belts obtained in Examples 1 to 9 and Comparative Examples 1 to 4 and 8 were suspended on each pulley of the testing machine, and the rotation speed of the drive pulley was 1000 rpm and the belt tension was increased under room temperature conditions. Tension is applied so as to be 50 N / Rib, and 5 ml of water is periodically (at intervals of about 30 seconds) injected into the friction transmission surface of the V-ribbed belt near the outlet of the drive pulley to cause misalignment (misalignment). The angle (sound limit angle) at which the sound (near the entrance of the misaligned pulley) when the belt was run by shifting the pulley toward each pulley was obtained. The larger the pronunciation limit angle, the better the pronunciation resistance. Normally, the belt comes off the pulley at around 3 ° (that is, the ribs are displaced), and the power is not transmitted normally.

The evaluation of the belt after running is as follows: a drive pulley (Dr.) with an outer diameter of 120 mm, an idler pulley (IDL) with an outer diameter of 85 mm, a driven pulley (Dn.) With an outer diameter of 120 mm, and a tension pulley (Ten.) With an outer diameter of 45 mm. The belt was used after being run by the running tester having the layout shown in FIG. A 6PK1100 V-ribbed belt was hung on each pulley of the testing machine, and the belt was adjusted so that the winding angle of the belt around the idler pulley was 120 °, the winding angle of the belt around the tension pulley was 90 °, and the belt tension was 395N. A sound limit angle test was performed on a belt that had been run for 200 hours with the rotation speed of the drive pulley set to 4900 rpm (the direction of rotation is the direction of the arrow in the figure), the load of the driven pulley set to 8.8 kW, and the atmospheric temperature set to 140 ° C.

2) Water injection resistance sound resistance test The water injection resistance sound resistance test was evaluated by running the 6PK980 V-ribbed belts obtained in Examples 10 to 17 and Comparative Examples 5 to 7 on the testing machine shown in the layout shown in FIG. The testing machine includes a drive pulley (Dr.) with a diameter of 140 mm, a tension pulley 1 (Ten. 1) with a diameter of 60 mm, a driven pulley 1 (Dn. 1) with a diameter of 50 mm, and a tension pulley 2 (Ten. 2) with a diameter of 60 mm. And a driven pulley 2 (Dn.2) having a diameter of 111 mm was provided. The rotation speed of the drive pulley was varied at 800 ± 160 rpm. The load of the driven pulley 1 was 16 N · m, and the load of the driven pulley 2 was no load. The belt tension was 200 N / 6 ribs. Water was intermittently injected from the compression rubber layer side of the belt at the center positions of the drive pulley and the driven pulley 2. Water injection was performed once every 60 seconds (5 seconds). The amount of water injected was 100 cc / sec (500 cc / 5 sec). The test temperature (atmospheric temperature) was 25 ° C., and the test time was 60 minutes. The presence or absence of abnormal noise during the test was confirmed by hearing.

The evaluation of the belt after running is as follows: a drive pulley (Dr.) having a diameter of 55 mm, an idler pulley 1 (Id.1) having a diameter of 65 mm, an idler pulley 2 (Id.2) having a diameter of 55 mm, and a driven pulley (Dn. 2) having a diameter of 55 mm. ) Are arranged in order, and the belt after running on the 4-axis running tester having the layout shown in FIG. 6 was used. A 6PK980 V-ribbed belt is hung on each pulley of the 4-axis running tester, the ambient temperature is 60 ° C, the rotation speed of the drive pulley is 2000 rpm, the idler pulley and driven pulley are unloaded, and the belt tension is 300 N / rib. A water injection resistance sound resistance test was conducted on the belt that had been run for a long time.

3) Transmission performance test For the transmission performance test, a testing machine with a layout shown in FIG. 7 in which a drive pulley (Dr.) having a diameter of 120 mm and a driven pulley (Dn.) With a diameter of 120 mm were arranged in this order was used. Then, a 3PK1100 V-ribbed belt is hung on both pulleys of the testing machine, and the drive pulley is run under the test conditions of 2000 rpm and a belt tension of 15.3 kgf / 3 ribs to gradually apply a load to the driven pulley and drive pulley. 300 ml of water was periodically (at intervals of about 60 seconds) poured into the friction transmission surface of the V-ribbed belt near the entrance of the belt, and the transmission power (kw) when the slip ratio of the belt became 2% was measured.

4) Endurance running test (high temperature and low tension bending fatigue test)
FIG. 8 shows a drive pulley (Dr.) having an outer diameter of 120 mm, an idler pulley (IDL) having an outer diameter of 85 mm, a driven pulley (Dn.) With an outer diameter of 120 mm, and a tension pulley (Ten.) With an outer diameter of 45 mm arranged in this order. A layout tester was used. A 3PK1100 V-ribbed belt was hung on each pulley of the testing machine, and the winding angle of the V-ribbed belt around the tension pulley was adjusted to 90 ° and the winding angle around the idler pulley was adjusted to 120 °. The rotation speed of the drive pulley was 4900 rpm (the direction of rotation is the direction of the arrow in the figure), the belt tension was 40 kgf / 3 ribs, the atmosphere temperature was 120 ° C., and the driven pulley was given a load of 12 PS to run for up to 600 hours. .. If an abnormality such as a crack occurred in the rubber layer of the belt before reaching 600 hours, the running was stopped by judging that time as the life. When no failure or abnormality occurred that would reach the end of the running life even after completing 600 hours, the belt was judged to have a running life of 600 hours or more, and was judged to be a belt having excellent crack resistance.

5) Measurement of transmission loss (torcross) A biaxial traveling tester having a layout shown in FIG. 9 composed of a drive pulley (Dr.) having a diameter of 55 mm and a driven pulley (Dn.) With a diameter of 55 mm was used. The drive torque when a 6PK1100 V-ribbed belt is hung on the testing machine, a predetermined initial tension is applied to the V-ribbed belt with a tension of 500 N / belt, and the drive pulley is rotated at 2000 rpm with no load on the driven pulley. The difference from the driven torque was calculated as the torque cross. It should be noted that the torque cloth obtained by this measurement includes not only the torque cloth caused by the V-ribbed belt but also the torque cloth caused by the bearing of the testing machine. Therefore, a metal belt (material: maraging steel) in which the torque cloth as a belt is considered to be substantially 0 is run in advance, and the difference between the driving torque and the driven torque is obtained as the torque cloth (bearing loss) caused by the bearing. Then, the value obtained by subtracting the torcross (bearing loss) caused by the bearing from the torcross (torcross caused by the belt and the bearing) calculated by running the V-ribbed belt was obtained as the torcross caused by the belt alone. The above-mentioned torcross (bearing loss) is the torcross when the metal belt is run at a predetermined initial tension (for example, when the V-ribbed belt is run at an initial tension of 500 N / one belt, the metal belt is run at this initial tension. The bearing loss will be the bearing loss when it is made to work).

When transmitting power, an energy loss (transmission loss) occurs. Examples of this energy loss include an internal loss due to self-heating of the rubber composition constituting the belt and a bending loss due to bending deformation of the belt. Normally, the "torque" value calculated by the difference between the drive torque value on the drive shaft and the driven torque value on the driven shaft is used as an index of energy loss, and the smaller the torque cross, the better the transmission efficiency (less transmission loss). ), And it is also used as an index of fuel efficiency in automobile engines and the like. In this test as well, the transmission efficiency, which affects fuel efficiency, was compared based on the measurement results of Torcross.

The evaluation results of Examples and Comparative Examples are shown in Tables 4 to 6.

As shown in Table 4, Examples 1 to 9 were examples in which polyvinylpyrrolidone (PVP) was used as a pronunciation resistance improving agent. As is clear from Tables 1 and 4, the physical characteristics of the rubber composition alone are grip force (magnitude of friction coefficient), μ-V characteristics (change in μ with increasing sliding speed), internal heat generation, and elastic characteristics. As a result, a high level of sound resistance, transmission performance, transmission efficiency (torcross), and durable life (crack resistance) when exposed to water was secured.

Specifically, regarding the surface layer rubber composition, as a rubber composition in which the type of PVP-based resin is changed, with respect to the rubber composition B (Example 1) containing polyvinylpyrrolidone 1 (K value 27.0 to 33.0). A rubber composition C using polyvinylpyrrolidone 2 having a K value of 88.0 to 96.0 (Example 2) and a rubber composition D using polyvinylpyrrolidone 3 having a K value of 22.5 to 27.0 (Example 2). In Examples 2 and 3 using Example 3), the results were the same as those in Example 1.

Further, the ratio of PVP to the rubber composition B (Example 1) was varied from 1 part by mass to 25 parts by mass, and the ratio of PVP to the rubber composition B (5 parts by mass; Example 1) was adjusted. Weight-reduced rubber composition E (1 part by mass; Example 4), rubber composition F with increased proportion of PVP (7 parts by mass; Example 5), rubber composition G (10 parts by mass; Example 6), The following tendencies are observed for the rubber composition H (15 parts by mass; Example 7), the rubber composition I (20 parts by mass; Example 8), and the rubber composition J (25 parts by mass; Example 9). It was.

In Example 1 (5 parts by mass), the effects of the sound resistance improver (PVP) include grip force (magnitude of friction coefficient), μ-V characteristics (change in μ with increasing slip speed), internal heat generation, and so on. It has an excellent balance of elastic properties, and as a result, a high level of belt performance can be ensured in terms of sound resistance and transmission performance when exposed to water, transmission efficiency (torcross), and durable life (crack resistance). On the other hand, in Example 4 (1 part by mass) in which the amount of PVP was reduced, the result was that the balance of each characteristic was excellent as in Example 1.

Example 5 (7 parts by mass), Example 6 (10 parts by mass), Example 7 (15 parts by mass), Example 8 (20 parts by mass) in which the amount of PVP was increased with respect to Example 1 (5 parts by mass). ), In Example 9 (25 parts by mass), the internal heat generation tended to increase as the proportion of PVP increased, but the result was that the balance of each characteristic was excellent as in Example 1. Since the change is slight between Example 8 (20 parts by mass) and Example 9 (25 parts by mass), it can be said that the effect of PVP is saturated at 20 parts by mass (addition of more than that reduces economic efficiency). It can be said). From the above results, it was found that the ratio of PVP is preferably 1 to 20 parts by mass from the viewpoint of the balance of each characteristic and economic efficiency.

In Comparative Example 1 in which the surface layer was not formed in the configurations of Examples 1 to 9, the result was that the belt performance was inferior in sound resistance.

In Comparative Examples 2 and 3 in which a surfactant was added as a sound resistance improving agent in the configurations of Examples 1 to 9, the transmission performance and the transmission efficiency (torcross) at the time of being exposed to water were inferior.

In Comparative Example 4 in which polyvinyl alcohol particles were added as a sound resistance improving agent in the configurations of Examples 1 to 9, cracks were generated in the rubber layer of the belt in the durability running test.

In Table 5, belts containing knitted fabric in the surface layer were evaluated, but compared with the test in Table 4, the sound resistance when exposed to water was evaluated in a test under more severe conditions. Examples 10 to 16 in which the surface layer rubber composition contains PVP are examples in which the type or ratio of PVP is changed as the surface layer rubber composition containing knitted fabric, but all of them are not limited to the belt before running. No abnormal noise was generated even on the belt after running for 300 hours. By using PVP, it can be said that the effect on water injection resistance sound at a high level can be sustained for a long period of time.

Example 17 is an example in which the compressed rubber layer also contains PVP, but the result was the same as that of Example 15. As a result, it was found that even if the compressed rubber layer contains PVP, if it is in a small amount, it does not affect the physical properties of the compressed rubber layer. However, considering economic efficiency, a technique for blending PVP in the compressed rubber layer. It can be said that the significance is small.

On the other hand, in Comparative Example 5 in which the surface layer does not contain PVP, no abnormal noise was generated during the 60-minute water injection test on the belt before running, but abnormal noise was generated in 45 minutes on the belt after running. did. Further, also in Comparative Example 6 in which a surfactant was used as the sound resistance improving agent and Comparative Example 7 in which polyvinyl alcohol (PVA) was used, no abnormal noise was generated on the belt before running, but after running. Abnormal noise was generated on the belt in a short time.

From the results in Table 5, the transmission performance (transmission power when exposed to water) and transmission efficiency (torcross) were compared among Examples 10 to 16 and Comparative Examples 5 to 7, which are belts containing knitted fabric on the surface layer. There was no significant difference except that in Example 6 (surfactant), the torque cloth was large. However, compared to belts without knitted fabric on the surface layer, belts containing knitted fabric on the surface layer have higher transmission performance (transmission power when exposed to water) as a characteristic of knitted fabric covering belts, while transmission efficiency is higher. It tended to be smaller (the belt cloth was larger).

Considering the results in Tables 4 and 5, a belt having a knitted fabric as the surface layer is more suitable for applications where sound resistance is important, and a surface layer is suitable for applications where fuel efficiency (reduction of torque cross) is important. However, it can be said that a belt that does not include knitted fabric is more suitable.

Comparative Example 8 shown in Table 6 is an example corresponding to the aspect of Patent Document 3 [a binder resin (polypropylene) is used instead of the elastomer]. In Comparative Example 8, since the grip property is inferior to that of Examples 1 to 9 in which the rubber composition for the surface layer contains PVP, it is easy to slip during running and the transmission performance (transmission power at the time of water reception) is improved. It decreased, and even in the endurance running for 600 hours, the life was reached early (280 hours) due to the influence of slip. It has been clarified that the form contained in the surface layer rubber composition is superior in gripability to the form in which PVP is fixed with a binder resin, and thus is superior in terms of transmission performance and durability.

The friction transmission belt of the present invention can be preferably used as a friction transmission belt such as a flat belt; a wrapped V belt, a low edge V belt, a low edge cogged V belt, and a V ribbed belt.

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

Claims (9)

A friction transmission belt having a friction transmission surface at least partially in contact with a pulley and containing a compressed rubber layer formed of a cured product of a rubber composition, wherein a polyvinylpyrrolidone-based surface is formed on the surface of the friction transmission surface. A friction transmission belt on which a surface layer containing a cured product of a rubber composition containing a resin and an elastomer component is laminated. The friction transmission belt according to claim 1, wherein the surface layer is formed of a cured product of the rubber composition containing the polyvinylpyrrolidone resin and the elastomer component. The friction transmission belt according to claim 1, wherein the surface layer further includes a cloth. The friction transmission belt according to any one of claims 1 to 3, wherein the elastomer component contains an ethylene-α-olefin elastomer. The friction transmission belt according to any one of claims 1 to 4, wherein the polyvinylpyrrolidone resin has a K value of 10 to 100. The friction transmission belt according to any one of claims 1 to 5, wherein the ratio of the polyvinylpyrrolidone-based resin is 1 to 20 parts by mass with respect to 100 parts by mass of the elastomer component. The friction transmission belt according to any one of claims 1 to 6, wherein the rubber composition for forming the surface layer does not contain a binder resin. The friction transmission belt according to any one of claims 1 to 7, wherein the rubber composition for forming the compressed rubber layer does not contain a polyvinylpyrrolidone-based resin. The friction transmission belt according to any one of claims 1 to 8, which is a V-ribbed belt or a low-edge V-belt.

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