WO2015146033A1 - Friction transmission belt - Google Patents

Abstract

In this friction transmission belt (B), a pulley contact portion formed from a rubber composition is included on a belt body (10), and multiple recesses (16) are formed in the pulley contact surface of the pulley contact portion. The shapes of the openings of the recesses (16) on the pulley contact surface are elongate in one direction, and the average aspect ratio of said shapes is 1.2-10.

Description

Friction transmission belt

This disclosure relates to a friction transmission belt.

V-ribbed belts are widely used as friction transmission belts that transmit the power of engines mounted on automobiles to drive auxiliary equipment. If rainwater or the like adheres to such a V-ribbed belt in the rain, belt slip or the like becomes large and abnormal noise is generated.

On the other hand, Patent Document 1 proposes that a friction transmission belt is formed of a porous rubber composition to suppress a reduction in transmission capability and generation of abnormal noise when wet.

JP 2007-255635 A

However, with respect to the performance required for the friction transmission belt, the bubble rate of the rubber disclosed in Patent Document 1 is insufficient for suppressing abnormal noise, and the strength of the belt is lowered, so that the bubble rate is further reduced. There is a problem that it cannot be raised.

In view of this, an object of the technology of the present disclosure is to provide a friction transmission belt that can further suppress abnormal noise during flooding.

In order to achieve the above object, a friction transmission belt according to the present disclosure is a friction transmission belt in which a pulley contact portion formed of a rubber composition is included in a belt body, and a plurality of pulley contact surfaces of a pulley contact portion are provided on a pulley contact surface. A recess is formed, and the opening of the recess on the pulley contact surface has a long shape on one side, and the average aspect ratio of the shape is 1.2 or more and 10 or less.

According to such a friction transmission belt, even when the belt gets wet, it is easily drained by the concave portion, and noise can be suppressed. In particular, even when the area of the opening of the concave portion is the same, by making the concave portion having the shape having the aspect ratio as described above, the effect of suppressing drainage and noise is high.

When the sliding direction of the friction transmission belt is 0 ° on the pulley contact surface, the average angle in the longitudinal direction of the opening may be included in the range of −45 ° to + 45 °.

In such a case, it is possible to more reliably suppress abnormal noise during flooding.

Further, on the pulley contact surface, the dimension in the direction perpendicular to the longitudinal direction of the opening may be 200 μm or less.

When the dimension exceeds 200 μm, the durability of the belt is lowered, so avoiding this, it is preferable to set it to 200 μm or less.

As described above, according to the friction transmission belt of the present disclosure, by providing a long concave portion on one side of the pulley contact surface, it is possible to suppress abnormal noise during flooding.

FIG. 1 is a perspective view illustrating a V-ribbed belt according to an embodiment of the present disclosure. 2 (a) and 2 (b) are views showing a recess formed on the pulley contact surface in the V-ribbed belt of FIG. FIG. 3 is a pulley layout diagram of the accessory drive belt transmission. 4 (a) and 4 (b) are explanatory views showing a method for manufacturing a V-ribbed belt. FIG. 5 is a diagram showing a pulley layout of a belt running test machine for belt durability evaluation.

Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 shows a V-ribbed belt B (friction transmission belt) according to an embodiment of the present disclosure. The V-ribbed belt B according to the present embodiment is used for, for example, an auxiliary machine drive belt transmission device provided in an engine room of an automobile. The V-ribbed belt B according to the present embodiment has, for example, a belt circumferential length of 700 to 3000 mm, a belt width of 10 to 36 mm, and a belt thickness of 3.5 to 5.0 mm.

The V-ribbed belt B according to the present embodiment includes a V-ribbed belt main body 10 configured as a triple layer of a compression rubber layer 11 on the belt inner peripheral side, an intermediate adhesive rubber layer 12 and a back rubber layer 13 on the belt outer peripheral side. In the adhesive rubber layer 12, a core wire 14 is embedded so as to form a spiral having a pitch in the belt width direction.

The compression rubber layer 11 is provided so that a plurality of V ribs 15 hang down to the inner peripheral side of the belt. The plurality of V ribs 15 are each formed in a ridge having a substantially inverted triangular cross section extending in the belt length direction, and arranged in parallel in the belt width direction. Each V-rib 15 has, for example, a rib height of 1.5 to 3.0 mm and a width between base ends of 1.0 to 3.6 mm. The number of ribs is, for example, 3 to 6 (in FIG. 1, the number of ribs is 6). The compressed rubber layer 11 is formed of a rubber composition obtained by heating and pressurizing an uncrosslinked rubber composition in which various compounding agents are blended and kneaded with a rubber component and then crosslinking with a crosslinking agent.

Further, a large number of recesses 16 are formed on the surface of the compressed rubber layer 11. This is shown in FIGS. 2 (a) and 2 (b).

FIG. 2 (a) shows the surface of the compressed rubber layer 11 (pulley contact surface) of the V-ribbed belt B, and represents only a small number of the recesses 16 formed therein. The recess 16 has a long opening on one side on the pulley contact surface, and the average aspect ratio of the shape is 1.2 or more and 10 or less. The aspect ratio is further shown in FIG. FIG. 2B shows the shape of the opening in the pulley contact surface of one recess 16, and the longitudinal direction thereof is dimension a, and the lateral direction (direction perpendicular to the longitudinal direction) is dimension b. It is shown that. At this time, the aspect ratio is a / b.

The longitudinal direction of the concave portion 16 is in the range of −45 ° to + 45 ° on average when the sliding direction 17 of the V-ribbed belt B is 0 °.

In addition, the recessed part 16 is formed by mix | blending the thing which aggregated the hollow particle with the binder with the rubber composition which comprises the compression rubber layer 11, for example.

The hollow particles may be of an expanding type. For example, it is a thermally expandable sphere in which a low-boiling hydrocarbon is encapsulated in a thermoplastic polymer cell such as Advancel EM403 manufactured by Sekisui Chemical Co., Ltd. This is because the low-boiling hydrocarbons encapsulated by heating expand, and at the same time, the thermoplastic shell softens, so that it expands rapidly and becomes hollow. Other examples include those of 092-40 and 092-120 acrylonitrile copolymers manufactured by Nippon Philite Co., Ltd., EHM303 and EMS-022 manufactured by Sekisui Chemical Co., Ltd. Can be mentioned.

For example, the hollow particles preferably have a particle size of 100 μm or less. Moreover, it is preferable that the compounding quantity with respect to 100 mass parts of base elastomers is 1 to 15 mass parts for hollow particles.

The hollow particles may be of a type that does not expand. For example, thermal expansion microcapsules 920DE80d30 manufactured by Nippon Philite Co., Ltd. can be used. In this case, the initial particle size is preferably 40 μm to 120 μm, more preferably 80 μm to 100 μm.

Alternatively, the expanding hollow particles and a chemical foaming agent such as Cellmic CE manufactured by Sankyo Kasei Co., Ltd. may be used in combination.

Examples of the rubber component of the rubber composition forming the compressed rubber layer 11 include ethylene-α-olefin elastomer, chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber (H-NBR), and the like. Can be mentioned. The rubber component may be composed of a single species or a blend of a plurality of species.

Examples of the compounding agent include a reinforcing material such as carbon black, a vulcanization accelerator, a crosslinking agent, an antiaging agent, and a softening agent.

As a reinforcing material, for example, carbon black, channel black; furnace black such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, N-234; FT, MT, etc. Thermal black; acetylene black. Silica is also mentioned as a reinforcing agent. The reinforcing agent may be composed of a single species or a plurality of species. The reinforcing material preferably has a blending amount of 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component, from the viewpoint of achieving a good balance between wear resistance and bending resistance.

Examples of the vulcanization accelerator include metal oxides such as magnesium oxide and zinc oxide (zinc white), metal carbonates, fatty acids such as stearic acid, and derivatives thereof. The vulcanization accelerator may be composed of a single species or a plurality of species. The amount of the vulcanization accelerator is 0.5 to 8 parts by mass with respect to 100 parts by mass of the rubber component.

Examples of the crosslinking agent include sulfur and organic peroxides. As the crosslinking agent, sulfur may be used, organic peroxide may be used, or both of them may be used in combination. In the case of sulfur, the crosslinking agent is preferably used in an amount of 0.5 to 4.0 parts by mass with respect to 100 parts by mass of the rubber component, and in the case of an organic peroxide, the compounding amount with respect to 100 parts by mass of the rubber component is, for example, 0. .5 to 8 parts by mass.

Antiaging agents include amine-based, quinoline-based, hydroquinone derivatives, phenol-based and phosphite-based agents. The anti-aging agent may be composed of a single species or a plurality of species. The anti-aging agent is, for example, 0 to 8 parts by mass with respect to 100 parts by mass of the rubber component.

Examples of the softener include petroleum-based softeners, mineral oil-based softeners such as paraffin wax, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, fallen raw oil, waxy wax, rosin And vegetable oil-based softeners such as pine oil. The softener may be composed of a single species or a plurality of species. The amount of the softener other than the petroleum-based softener is, for example, 2 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

In addition, layered silicates such as smectite group, vermiculite group, kaolin group and the like may be included as a compounding agent.

Further, the compression rubber layer 11 can contain a friction coefficient reducing material. Examples of the friction coefficient reducing material include short fibers such as nylon short fibers, vinylon short fibers, aramid short fibers, polyester short fibers, cotton short fibers, and ultrahigh molecular weight polyethylene resins.

Next, the adhesive rubber layer 12 is formed in a band shape having a horizontally long cross section and has a thickness of, for example, 1.0 to 2.5 mm. The back rubber layer 13 is also formed in a band shape having a horizontally long cross section, and has a thickness of, for example, 0.4 to 0.8 mm. The surface of the back rubber layer 13 is preferably formed in a form in which the texture of the woven fabric is transferred from the viewpoint of suppressing the sound generated between the back rubber layer 13 and the flat pulley in contact with the belt back surface. The adhesive rubber layer 12 and the back rubber layer 13 are formed of a rubber composition obtained by heating and pressurizing an uncrosslinked rubber composition in which various compounding agents are blended into a rubber component and then kneading and crosslinking with a crosslinking agent. . The back rubber layer 13 is preferably formed of a rubber composition that is slightly harder than the adhesive rubber layer 12 from the viewpoint of suppressing the occurrence of adhesion due to contact with the flat pulley with which the belt back contacts. The compressed rubber layer 11 and the adhesive rubber layer 12 constitute a V-ribbed belt main body 10 and, instead of the back rubber layer 13, for example, a woven fabric formed of yarns such as cotton, polyamide fiber, polyester fiber, and aramid fiber. Further, a configuration in which a reinforcing fabric composed of a knitted fabric, a nonwoven fabric or the like is provided may be used.

Examples of the rubber component of the rubber composition forming the adhesive rubber layer 12 and the back rubber layer 13 include ethylene-α-olefin elastomer, chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber ( H-NBR) and the like. The rubber component of the adhesive rubber layer 12 and the back rubber layer 13 is preferably the same as the rubber component of the compressed rubber layer 11.

Examples of the compounding agent include a reinforcing material such as carbon black, a vulcanization accelerator, a crosslinking agent, an anti-aging agent, a softening agent and the like, as in the case of the compressed rubber layer 11.

The compressed rubber layer 11, the adhesive rubber layer 12, and the back rubber layer 13 may be formed of a rubber composition having a different composition, or may be formed of a rubber composition having the same composition.

Further, the core wire 14 is composed of twisted yarns such as polyester fiber (PET), polyethylene naphthalate fiber (PEN), aramid fiber, and vinylon fiber. The core wire 14 is subjected to an adhesive treatment that is heated after being immersed in an RFL aqueous solution before molding and / or an adhesive treatment that is dried after being immersed in rubber paste in order to impart adhesion to the V-ribbed belt main body 10. .

Next, FIG. 3 shows a pulley layout of the auxiliary drive belt transmission device 20 for an automobile using the V-ribbed belt B according to the present embodiment. The accessory drive belt transmission device 20 is of a serpentine drive type in which a V-ribbed belt B is wound around six pulleys including four rib pulleys and two flat pulleys to transmit power.

The auxiliary drive belt transmission device 20 includes a power steering pulley 21 at the uppermost position in FIG. 3, an AC generator pulley 22 disposed slightly diagonally to the right of the power steering pulley 21, and diagonally to the left of the power steering pulley 21. A flat pulley tensioner pulley 23 disposed obliquely above and to the left of the AC generator pulley 22, a flat pulley water pump pulley 24 disposed obliquely to the left of the AC generator pulley 22 and directly below the tensioner pulley 23, and a tensioner A crankshaft pulley 25 disposed obliquely below the left of the pulley 23 and the water pump pulley 24 and an air conditioner pulley 26 disposed obliquely below the left of the water pump pulley 24 and the crankshaft pulley 25 are provided. Among these, all except the tensioner pulley 23 and the water pump pulley 24 which are flat pulleys are rib pulleys. These rib pulleys and flat pulleys are made of, for example, a metal press-worked product, a casting, a resin molded product such as nylon resin, phenol resin, and the diameter of the pulley is 50 to 150 mm.

In this auxiliary machine drive belt transmission 20, after the V-ribbed belt B is wound around the power steering pulley 21 so that the V-rib 15 side comes into contact, and then around the tensioner pulley 23 so that the back surface of the belt comes into contact. Further, the crankshaft pulley 25 and the air conditioner pulley 26 are wound in order so that the V rib 15 side contacts, and further, the water pump pulley 24 is wound so that the back surface of the belt contacts, and the V rib 15 side contacts. Is wound around the AC generator pulley 22 and finally returned to the power steering pulley 21.

According to the V-ribbed belt B of the present embodiment, a large number of recesses 16 are formed on the surface of the V-rib 15 that is the pulley contact surface. Thus, for example, as described above, a belt transmission device for driving an accessory of an automobile. Even when it is used for water, it is possible to suppress the generation of abnormal noise. This is because water interposed between the belt and the pulley is taken into the recess 16 and then drained to the outside and quickly removed.

Further, the average aspect ratio of the recesses is 1.2 or more and 10 or less, and the average of the longitudinal direction of the recesses is in the range of −45 ° to + 45 ° when the friction transmission direction of the V-ribbed belt B is 0 °. . Thereby, it is possible to improve the drainage without increasing the bubble rate in the compressed rubber layer 11, and the friction that can more reliably suppress the abnormal noise when wet without causing a decrease in the durability of the belt or the like. A transmission belt can be realized. Further, since it is not necessary to increase the blending amount of the hollow particles, it becomes easy to design a rubber matrix portion for obtaining desired performances such as elastic modulus and wear resistance.

As this reason, it is considered that the capillary phenomenon is remarkably exhibited due to the shape having a large aspect ratio. Further, when the longitudinal direction of the concave portion is close to the sliding direction, water can be drained in the longitudinal direction of the concave portion as the belt slides, and drainage efficiency is improved. As a result, the suppression of abnormal noise becomes significant.

Next, a method for manufacturing the V-ribbed belt B will be described with reference to FIGS. 4 (a) and 4 (b).

In the manufacture of the V-ribbed belt B, an inner mold having a molding surface for forming the back surface of the belt in a predetermined shape on the outer periphery and a rubber sleeve having a molding surface for forming the inner side of the belt in a predetermined shape on the inner periphery are used.

First, after the outer periphery of the inner mold is covered with a rubber layer 13 ′ to be the back rubber layer 13, an uncrosslinked rubber sheet 12 b ′ for forming the outer portion 12 b of the adhesive rubber layer 12 is wound thereon.

Next, a twisted yarn 14 'serving as a core wire 14 is spirally wound thereon, and then an uncrosslinked rubber sheet 12a' for forming the inner portion 12a of the adhesive rubber layer 12 is wound thereon, and further An uncrosslinked rubber sheet 11 ′ for forming the compressed rubber layer 11 is wound on the top. At this time, as the uncrosslinked rubber sheet 11 ′ for forming the compressed rubber layer 11, a material in which hollow particles are blended is used. The uncrosslinked rubber sheet 11 ′ is preferably a mixture of 1 to 15 parts by mass of hollow particles aggregated with a binder with respect to 100 parts by mass of the base elastomer. It is more preferable that they are partially blended.

After that, a rubber sleeve is fitted onto the molded body on the inner mold and set in a molding pot. The inner mold is heated with high-temperature steam and the like, and the rubber sleeve is radially inward by applying high pressure. Press on. At this time, the rubber component flows and the crosslinking reaction proceeds, and the adhesion reaction of the twisted yarn 14 ′ to the rubber also proceeds. Further, the hollow particles are expanded by volatilization of pentane, hexane, or the like in the particles, thereby forming a large number of minute hollow portions. And thereby, a cylindrical belt slab (belt main body precursor) is shape | molded.

Here, the aggregate of hollow particles is formed as a hollow particle aggregate master batch by pelletizing after adding a binder to the hollow particles and kneading. In pelletizing, the size and aspect ratio of the master batch can be set, and consequently the size and aspect ratio of the recess 16 can be set. For example, by forming and using a hollow particle aggregate in which hollow particles are long aligned in one direction with a binder, the concave portion 16 can be made long in one side. Further, the direction of the hollow particle aggregate can be adjusted by calendaring, extrusion molding or the like for the uncrosslinked rubber sheet 11 '. By these things, the size, shape, directionality (longitudinal direction) and the like of the recesses can be controlled.

It should be noted that hollow particles that do not swell at the processing temperature from kneading to molding and a binder that does not melt at that temperature are used, and vulcanization is performed at a temperature equal to or higher than the foaming temperature of the hollow particles and the melting temperature of the binder. Thereby, hollow particles are formed in the formed compressed rubber layer 11 by the foaming of the hollow particles from the state of the aggregate. Of these cavities, the recess 16 is formed by the one exposed on the pulley contact surface.

In addition, it is desirable that the binder and the base elastomer of the uncrosslinked rubber sheet 11 ′ have a compatible combination. For example, a combination of polyethylene binder and EPDM, a combination of acrylonitrile binder and NBR, or the like.

Even when only hollow particles are blended with rubber without forming a hollow particle aggregate using a binder, not all the recesses are formed from a single hollow particle. It is possible to form a recess. However, when no binder is used, it is difficult to control the number of hollow particles contained in each hollow particle aggregate, the aspect ratio of the aggregate, etc., and it is also difficult to control the size and shape of the recesses. .

Next, after removing the belt slab from the inner mold and dividing the belt slab into several pieces in the length direction, the outer periphery of each is polished and cut to form the V rib 15, that is, the pulley contact portion. At this time, the recess 16 is formed on the pulley contact surface by the aggregate of hollow particles exposed on the pulley contact surface.

Finally, the belt slab, which is divided and formed with the V rib 15 on the outer periphery, is cut into a predetermined width, and the V-ribbed belt B is obtained by turning each side upside down.

Further, instead of forming the V rib 15 by cutting, a cylindrical mold having a molding surface provided with a plurality of rib grooves that form the inner side of the belt in a rib shape on the inner periphery may be used.

In this case, each belt material (rubber layer 13 ′, uncrosslinked rubber sheet 12b ′, twisted yarn 14 ′) is formed on the outer periphery of a rubber sleeve having a molding surface that forms a belt back surface in a predetermined shape on the outer periphery. The uncrosslinked rubber sheet 12a ′ and the uncrosslinked rubber sheet 11 ′) are sequentially wound.

After that, a rubber sleeve wrapped with a belt material is inserted and set in a cylindrical mold, the rubber sleeve inside the cylindrical mold is heated, and the rubber sleeve is expanded by water vapor, etc. Press toward. At this time, the base rubber flows and the crosslinking reaction proceeds, the adhesion reaction of the twisted yarn 14 'to the rubber also proceeds, and in addition, the outer peripheral portion of the belt material has a V shape due to the rib shape of the inner periphery of the cylindrical mold. Ribs 15 are formed. In this way, a cylindrical belt slab (belt body precursor) is formed. After cooling the molding pot, the rubber sleeve is removed from the cylindrical mold, and then the belt slab is removed.

Finally, the belt slab, which is divided and formed with the V rib 15 on the outer periphery, is cut into a predetermined width, and the V-ribbed belt B is obtained by turning each side upside down.

In the above description, the V-ribbed belt B is shown as the friction transmission belt. However, the belt is not particularly limited to this, and may be a low-edge type V-belt or the like.

Further, although the auxiliary drive belt transmission device 20 of the automobile is shown as the belt transmission device, the belt transmission device is not particularly limited to this, and may be a belt transmission device for general industries.

Hereinafter, the V-ribbed belt of the example will be described.

(Test evaluation belt)
V-ribbed belts of Examples 1 to 6 and Comparative Examples 1 to 6 shown in Table 1 were prepared.

<Example 1>
As a base elastomer, 100 parts by mass of ethylene propylene diene monomer (EPDM) (manufactured by JSR Corporation, trade name: EP22), 50 parts by weight of carbon black (manufactured by Tokai Carbon Co., Ltd., trade name: Seast 3), oil (Nihon Sun 15 parts by mass of a petroleum product, trade name: Thumper 2280), 1 part by mass of stearic acid (trade name: Lunac, manufactured by Kao Corporation), 5 parts by mass of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., trade name: Zinc Hana 3 types) , 1.5 parts by mass of sulfur (manufactured by Hosoi Chemical Co., Ltd., trade name: Oil Sulfur), 1 part by mass of vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name: MSA), vulcanization accelerator (Sanshin Chemical Industry) Product name: EM2) 3 parts by mass, hollow particles (manufactured by Sekisui Chemical Co., Ltd., product name: Advancel EM403) 1.5 parts by mass, binder (manufactured by Ouchi Shinsei Chemical Co., Ltd., product name: Sun) Click N) to form a V-ribbed belt forming the ribbed rubber layer using by blending 0.2 part by weight uncrosslinked elastomer composition by kneading, which was used as in Example A.

The adhesive rubber layer and the back rubber layer are made of an EPDM elastomer composition, the core wire is made of a polyethylene naphthalate fiber (PEN) twisted yarn, the belt length is 2280 mm, the width is 25 mm, and the thickness is 4. The number of ribs was 6 mm.

In addition, about a hollow particle and a binder, it blends beforehand and creates a hollow particle aggregate masterbatch. Further, two-stage kneading is performed as the elastomer kneading, and the hollow particle aggregate master batch is added in the second stage. The maximum processing temperature (about 115 ° C.) in the process from the second stage kneading to molding is lower than the foaming temperature of the hollow particles (about 145 ° C.) and the melting temperature of the binder (about 125 ° C.). Hollow particles exist as unfoamed aggregates. Vulcanization is carried out at a temperature higher than the foaming temperature of the hollow particles and the melting temperature of the binder (about 145 ° C. to 180 ° C.). At this time, the hollow particles are foamed to form recesses on the pulley contact surface.

In addition, the recesses are aligned in the sheet arrangement direction by calendar processing. Therefore, the direction of the longitudinal direction of the concave portion with respect to the sliding direction of the belt can be set by setting the cutting direction of the belt. In Example 1, cutting was performed so that the sheet row direction was the sliding direction of the belt. In the following, the belt sliding direction is assumed to be 0 °, and the average of the longitudinal direction of the concave portion is represented by the angle with respect to this.

<Example 2>
The V-ribbed belt of Example 1 was produced in the same manner as Example 1 except for the point relating to the hollow particle aggregate.

Specifically, in Example 2, a hollow particle aggregate masterbatch having a larger aspect ratio than that in Example 1 was used. This can be obtained by kneading the binder and hollow particles and extruding them into a linear shape and cutting (pelletizing) them into a longer shape than in the case of Example 1.

<Example 3>
The V-ribbed belt of Example 3 was formed in the same manner as the V-ribbed belt of Example 1 except that the belt was cut out so that the sheet running direction was oblique to the sliding direction of the belt.

<Example 4>
The V-ribbed belt of Example 4 was prepared in the same manner as the V-ribbed belt of Example 1.

<Example 5>
The V-ribbed belt of Example 5 is the same as that of Example 5 except that the cutting of the belt is performed so that the sheet running direction is inclined with respect to the sliding direction of the belt (as opposed to the case of Example 3). 1 was prepared in the same way as the V-ribbed belt.

<Example 6>
The V-ribbed belt of Example 6 was prepared in the same manner as the V-ribbed belt of Example 1.

<Comparative Example 1>
The V-ribbed belt of Comparative Example 1 was prepared in the same manner as the V-ribbed belt of Example 1 except that the hollow particle aggregate was not blended.

<Comparative example 2>
The V-ribbed belt of Comparative Example 2 was prepared in the same manner as the V-ribbed belt of Example 1 except that a hollow particle aggregate master batch having a smaller aspect ratio than that of Example 1 was used.

<Comparative Example 3>
The V-ribbed belt of Comparative Example 3 was prepared in the same manner as the V-ribbed belt of Example 1 except that a hollow particle aggregate masterbatch having a larger aspect ratio than that of Example 2 was used.

<Comparative example 4>
The V-ribbed belt of Comparative Example 4 has a V-shaped belt of Example 3 except that the belt is cut out so that the direction of the sheet is inclined with respect to the sliding direction of the belt. It was created in the same way as the ribbed belt.

<Comparative Example 5>
The V-ribbed belt of Comparative Example 5 was produced in the same manner as the V-ribbed belt of Example 3 except that the sheet cutting direction was cut out with the intention of the sheet running direction being perpendicular to the sliding direction of the belt. .

<Comparative Example 6>
The V-ribbed belt of Comparative Example 6 has a V-shaped belt of Example 3 except that the belt is cut out so that the direction of the sheet is inclined with respect to the sliding direction of the belt. It was created in the same way as the ribbed belt.

<Comparative Example 7>
The V-ribbed belt of Comparative Example 7 was prepared in the same manner as the V-ribbed belt of Example 1, except that a hollow particle aggregate masterbatch having a larger size than that of Example 1 was used.

<Evaluation of pronunciation>
Each of the V-ribbed belts of Examples 1 to 6 and Comparative Examples 1 to 7 is attached to a belt drive device for driving an auxiliary machine of an automobile engine having a large rotational fluctuation and a large load, and 120 ml / min is applied to the V-ribbed belt in an idling state. An amount of water was dropped, and the sound pressure at that time was measured. 90 dB or more was evaluated as “large”, 80 dB or more and less than 90 dB as “medium”, 75 dB or more and less than 80 dB as “small”, 70 dB or more and less than 75 dB as “small”, and less than 70 dB as “none”. Note that the measurement was performed in the idling state because sound generation becomes most noticeable when the engine is running at a low speed.

<Belt durability test>
FIG. 5 shows a pulley layout of the belt running test machine 30 for durability evaluation of the V-ribbed belt B.

This belt running test machine 30 is arranged on the right side in the middle in the up-down direction, with a large-diameter rib pulley having a pulley diameter of 120 mm (upper side is a driven pulley and the lower side is a driving pulley) disposed on the upper and lower sides. It comprises a small-diameter rib pulley 33 with a pulley diameter of 45 mm. The small-diameter rib pulley 33 is positioned so that the belt winding angle is 90 °.

For each V-ribbed belt B of Examples 1 to 6 and Comparative Examples 1 to 7, the rib pulley 53 with a small diameter is pulled to the side so that the set weight of 834N is loaded while being wound around the three rib pulleys 51 to 53. A belt running test was performed in which the lower rib pulley 32 as a driving pulley was rotated at a rotational speed of 4900 rpm under an atmospheric temperature of 23 ° C. And the time until a crack generate | occur | produces on the rib surface was measured.

<Measurement of recess aspect ratio, short hole diameter, orientation>
For each of the V-ribbed belts B of Examples 1 to 6 and Comparative Examples 1 to 7, the pulley contact surface was observed with a microscope, and the longitudinal dimension and the lateral dimension (short hole diameter) of each of the 50 recesses were observed. And the aspect ratio was calculated. Moreover, it measured also about the direction of the longitudinal direction. The average value was obtained from the measurement results of 50 recesses. In addition, when the rectangle which four sides each contact | connect one or more points to the outline of the recessed part in a pulley contact surface is made into the longitudinal direction, and the direction orthogonal to this is made into the short direction.

(Test evaluation results)
For each of the V-ribbed belts B of Examples 1 to 6 and Comparative Examples 1 to 7, the presence / absence of a recess, the aspect ratio of the recess shape, the angle in the longitudinal direction, the short hole diameter of the recess, the sound generation during water exposure, and the crack generation travel time Is shown in Table 1.

First, in Comparative Example 1 in which no recess is provided, the pronunciation after flooding is large.

Looking at the aspect ratio of the recess, in the range from 1.26 in Example 1 to 9.77 in Example 2, there is no or very little sound after flooding. On the other hand, in the case of the comparative example 2 whose aspect ratio is 1.06 which is smaller than that of the first embodiment, the sound generation after flooding is medium. Therefore, it is considered that the sound generation after flooding can be suppressed by making the concave portion long in one direction.

In Comparative Example 3 where the aspect ratio is 10.49, there is no sound after flooding. In this example, however, the cracking running time is 437 hours, which is significantly larger than the 498 hours of Example 2. Short. From this, it can be seen that if the aspect ratio is too large, the strength of the belt deteriorates.

From the above, it is considered that the average aspect ratio is desirably 1.2 or more and approximately 10 or less.

Further, in Example 3 in which the angle in the longitudinal direction is + 42.1 ° and Example 5 in which it is −43.5 °, there is no or very little sound generation after flooding. In contrast, Comparative Example 4 in which the angle in the longitudinal direction is + 49.4 ° and Comparative Example 5 in which it is −47.0 ° are medium and large in Comparative Example 5 in which + 89.9 °. Therefore, when the average of the longitudinal direction is aligned with the belt sliding direction, the sound generation after flooding becomes smaller, and when the belt sliding direction is 0 °, it is about −45 ° to + 45 °. Is considered desirable.

Further, in Example 6 in which the short hole diameter is 181 μm, the crack traveling time is 491 hours, which is somewhat shorter than 512 hours in Example 1 in which the short hole diameter is 121 μm. However, in Comparative Example 7 in which the short hole diameter is 211 μm, it is significantly short as 425 hours, which is significantly different from that in Example 6. From these, it is considered that the short hole diameter is desirably about 200 μm or less.

The friction transmission belt of the present disclosure can suppress abnormal noises when wet while maintaining strength and the like, and is also useful for an auxiliary drive belt transmission device for automobiles and belt transmission devices for general industries.

10 V-ribbed belt body 11 Compressed rubber layer 11 ′ Uncrosslinked rubber sheet 12 Adhesive rubber layer 12a Inner portion 12a ′ Uncrosslinked rubber sheet 12b Outer portion 12b ′ Uncrosslinked rubber sheet 13 Back rubber layer 13 ′ Rubber layer 14 Core wire 14 ′ Thread 15 V-rib 16 Recess 17 Sliding direction 20 Auxiliary drive belt transmission 21 Power steering pulley 22 AC generator pulley 23 Tensioner pulley 24 Water pump pulley 25 Crankshaft pulley 26 Air conditioner pulley 30 Belt running test machine 31 Rib pulley 32 Rib pulley 33 Rib pulley

Claims (3)

A friction transmission belt including a pulley contact portion formed of a rubber composition in a belt body,
A plurality of recesses are formed on the pulley contact surface of the pulley contact portion,
The friction transmission belt, wherein an opening of the concave portion on the pulley contact surface has a long shape on one side, and an average aspect ratio of the shape is 1.2 or more and 10 or less. The friction transmission belt according to claim 1,
On the pulley contact surface, when the sliding direction of the friction transmission belt is an angle of 0 °, the average of the longitudinal angle of the opening is in the range of −45 ° to + 45 °. Transmission belt. The friction transmission belt according to claim 1 or 2,
In the pulley contact surface, the dimension in the direction perpendicular to the longitudinal direction of the opening is 200 μm or less.

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