阅读说明：本技术 摩擦传动带 (Friction transmission belt ) 是由 木村胜起 大久保贵幸 于 2019-07-11 设计创作，主要内容包括：摩擦传动带(B)具有由橡胶组合物形成的动力传递面。橡胶组合物含有橡胶成分和短纤维(14)。橡胶成分以二烯含量为6.0质量％以上的EPDM为主要成分,短纤维(14)沿带宽方向取向地分散在橡胶成分中,短纤维(14)的长径比为100以上,橡胶组合物在25℃下带宽方向上的拉伸屈服应力为15.0MPa以上。(The friction transmission belt (B) has a power transmission surface formed of a rubber composition. The rubber composition contains a rubber component and short fibers (14). The rubber component comprises EPDM having a diene content of 6.0 mass% or more as a main component, short fibers (14) are dispersed in the rubber component so as to be oriented in the belt width direction, the aspect ratio of the short fibers (14) is 100 or more, and the tensile yield stress of the rubber composition in the belt width direction at 25 ℃ is 15.0MPa or more.)

1. A friction transmission belt having a power transmission surface formed of a rubber composition, characterized in that:

the rubber composition contains a rubber component and short fibers, wherein the rubber component mainly contains ethylene-propylene-diene monomer having a diene content of 6.0 mass% or more, the short fibers are dispersed in the rubber component so as to be oriented in the belt width direction, the aspect ratio of the short fibers is 100 or more, and the tensile yield stress of the rubber composition in the belt width direction at 25 ℃ is 15.0MPa or more.

2. The friction drive belt of claim 1 wherein:

the content of the short fiber in the rubber composition is 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the rubber component.

3. The friction drive belt of claim 1 or 2, wherein:

the short fiber contains one or more than two of para-aramid short fiber, meta-aramid short fiber, nylon 66 short fiber, polyester short fiber, ultrahigh molecular weight polyolefin short fiber, poly-p-phenylene benzobisoxazole short fiber, polyarylate short fiber, cotton, glass short fiber and carbon short fiber.

4. The friction drive belt of claim 3 wherein:

the short fiber contains para-aramid short fiber and nylon 66 short fiber, and the content of the para-aramid short fiber in the rubber composition is less than that of the nylon 66 short fiber in the rubber composition.

5. The friction drive belt according to any one of claims 1 to 4, characterized in that:

the short fibers have a fiber length of 1.0mm to 5.0 mm.

6. The friction drive belt according to any one of claims 1 to 5, characterized in that:

the short fibers have a fiber diameter of 5.0 to 30.0 [ mu ] m.

7. The friction drive belt according to any one of claims 1 to 6, characterized in that:

the rubber component in the rubber composition is crosslinked with an organic peroxide.

8. The friction drive belt of claim 7 wherein:

the rubber component in the rubber composition is also crosslinked with a co-crosslinking agent.

9. The friction drive belt of claim 8, wherein:

the blending amount of the co-crosslinking agent in the uncrosslinked rubber composition before crosslinking of the rubber composition is 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the rubber component.

10. The friction drive belt of claim 8 or 9, wherein:

the co-crosslinking agent contains at least one of N, N' -m-phenylene bismaleimide and zinc methacrylate.

11. The friction drive belt of claim 10 wherein:

the co-crosslinking agent contains N, N '-m-phenylene bismaleimide and zinc methacrylate, and the content of the N, N' -m-phenylene bismaleimide in the uncrosslinked rubber composition before crosslinking of the rubber composition is less than that of the zinc methacrylate in the uncrosslinked rubber composition before crosslinking of the rubber composition.

12. The friction drive belt according to any one of claims 1 to 11, characterized in that:

the EPDM content of ethylene is 45-60% by mass.

Technical Field

The present invention relates to a friction transmission belt.

Background

There is known a friction transmission belt made of a rubber composition in which short fibers are dispersed in a rubber component, EPDM (ethylene propylene diene monomer). For example, patent documents 1 and 2 disclose a v-ribbed belt in which a compression rubber layer and a tension rubber layer are formed, and the compression rubber layer and the tension rubber layer are formed of a rubber composition formed by dispersing nylon short fibers and cotton short fibers in an EPDM that is a rubber component.

Patent document 1: japanese laid-open patent publication No. 2013-127278

Patent document 2: japanese laid-open patent publication No. 2014-9749

Disclosure of Invention

The present invention is a friction transmission belt having a power transmission surface formed of a rubber composition containing a rubber component and short fibers (14). The rubber component comprises EPDM having a diene content of 6.0 mass% or more as a main component, short fibers (14) are dispersed in the rubber component so as to be oriented in the belt width direction, the aspect ratio of the short fibers (14) is 100 or more, and the tensile yield stress of the rubber composition in the belt width direction at 25 ℃ is 15.0MPa or more.

Drawings

FIG. 1 is a perspective view of a portion of an embodiment toothed V-belt;

fig. 2 is a cross-sectional view taken in the belt width direction of the toothed V-belt according to the embodiment;

fig. 3 is a cross-sectional view taken along the belt length direction of the toothed V-belt according to the embodiment;

fig. 4A is a first explanatory diagram showing a method of deriving the tensile yield stress;

fig. 4B is a second explanatory diagram showing a method of deriving the tensile yield stress;

fig. 5 is a diagram showing the arrangement of pulleys of the belt running test machine.

Detailed Description

The following describes embodiments in detail.

Fig. 1 to 3 show a toothed V-belt B according to an embodiment. The toothed V belt B according to the embodiment is, for example, an endless rubber friction transmission belt used as a power transmission member for shifting in a transmission device of a two-wheeled vehicle. The toothed V belt B according to the embodiment has a belt length of, for example, 500mm or more and 1200mm or less, a maximum belt width of, for example, 16mm or more and 30mm or less, and a maximum belt thickness of, for example, 8.0mm or more and 12.0mm or less.

The V-belt B according to the embodiment includes a V-belt body 10, a core wire 20, an inner reinforcing cloth 30, and an outer reinforcing cloth 40.

The cross-sectional shape of the V-belt body 10 in the belt width direction is an isosceles trapezoid. The angle formed by the two side surfaces of the V-belt body 10 is, for example, 24 ° or more and 36 ° or less. The V-belt body 10 has a compression rubber layer 11 provided on the inner peripheral side, a binding rubber layer 12 provided in the middle, and a tension rubber layer 13 provided on the outer peripheral side. Lower teeth forming portions 11a are arranged at a constant pitch on the inner periphery of the compression rubber layer 11, and the cross-sectional shape of the lower teeth forming portions 11a in the belt longitudinal direction is sinusoidal.

The compression rubber layer 11 is formed of a rubber composition. Various rubber compounding agents are compounded in a rubber component and kneaded to form an uncrosslinked rubber composition, and the uncrosslinked rubber composition is heated and pressurized to crosslink the rubber component, thereby obtaining a rubber composition. Both side surfaces of the compression rubber layer 11 constitute a power transmission surface formed of a rubber composition.

The rubber composition forming the compression rubber layer 11 contains a rubber component mainly composed of EPDM having a diene content of 6.0 mass% or more. The content of EPDM in the rubber component is 50 mass% or more, but as described later, from the viewpoint of obtaining excellent wear resistance of the power transmission surface, the content of EPDM in the rubber component is preferably 80 mass% or more, more preferably 90 mass% or more, and still more preferably 100 mass%. The rubber component may contain an ethylene- α -olefin elastomer other than EPDM, Chloroprene Rubber (CR), chlorosulfonated polyethylene rubber (CSM), hydrogenated nitrile rubber (H-NBR), or the like.

From the viewpoint of obtaining excellent wear resistance of the power transmission surface, the content of ethylene in the EPDM in the rubber component of the rubber composition forming the compression rubber layer 11 is preferably 45 mass% or more and 60 mass% or less, and more preferably 50 mass% or more and 55 mass% or less. When the rubber component contains a plurality of EPDM, the calculated ethylene content is an average value.

Among the rubber components of the rubber composition forming the compression rubber layer 11, examples of diene components in EPDM include: ethylidene Norbornene (ENB), dicyclopentadiene, 1, 4-hexadiene, and the like. Among them, ethylidene norbornene is preferable from the viewpoint of obtaining excellent abrasion resistance of the power transmission surface. The content of the diene in the EPDM is 6.0 mass% or more, but from the viewpoint of obtaining excellent wear resistance of the power transmission surface, the content of the diene in the EPDM is preferably 6.5 mass% or more and 12 mass% or less, more preferably 7.0 mass% or more and 8.0 mass% or less. When the rubber component contains a plurality of EPDM, the calculated diene content is an average value.

In the rubber component of the rubber composition forming the compression rubber layer 11, the mooney viscosity of EPDM at 125 ℃ is preferably 15ML from the viewpoint of obtaining excellent wear resistance of the power transmission surface₁₊₄(125 ℃) or higher and 40ML₁₊₄(125 ℃) or less, more preferably 15ML₁₊₄(125 ℃) or higher and 30ML₁₊₄(125 ℃) or less, and more preferably 25ML₁₊₄(125 ℃) or higher and 30ML₁₊₄(125 ℃) below. Mooney viscosity is measured based on Japanese Industrial Standard JIS K6300.

The rubber composition forming the compression rubber layer 11 contains short fibers 14 dispersed in the rubber component so as to be oriented in the width direction.

Examples of the short fibers 14 include: para-aramid short fibers (poly-p-phenylene terephthalamide short fibers, copolymerized p-phenylene-3, 4' -oxydiphenylene terephthalamide short fibers), meta-aramid short fibers, nylon 66 short fibers, polyester short fibers, ultrahigh molecular weight polyolefin short fibers, poly-p-phenylene benzobisoxazole short fibers, polyarylate short fibers, cotton, glass short fibers, carbon short fibers and the like. The short fibers 14 preferably contain one or more kinds of fibers. From the viewpoint of obtaining excellent wear resistance of the power transmission surface, the short fiber 14 more preferably contains at least one of a para-aramid short fiber and a nylon 66 short fiber, and further preferably contains a copolymerized para-phenylene-3, 4' -oxydiphenylene terephthalamide short fiber as the para-aramid short fiber. The short fibers 14 may be bonded or not bonded. Examples of the bonding treatment include: the long fiber before cutting is immersed in a base treatment agent containing an epoxy compound or an isocyanate compound and then heated, and the long fiber before cutting is immersed in an RFL aqueous solution and then heated.

From the viewpoint of obtaining excellent wear resistance of the power transmission surface, the content of the short fibers 14 in the rubber composition is preferably 10 parts by mass or more and 30 parts by mass or less, more preferably 15 parts by mass or more and 25 parts by mass or less, with respect to 100 parts by mass of the rubber component. In the case where the short fiber 14 contains both the para-aramid short fiber and the nylon 66 short fiber, the content of the para-aramid short fiber in the rubber composition is preferably smaller than the content of the nylon 66 short fiber in the rubber composition. The content of the para-aramid short fiber in the rubber composition is preferably 1 part by mass or more and 10 parts by mass or less, more preferably 4 parts by mass or more and 7 parts by mass or less, with respect to 100 parts by mass of the rubber component. The content of the nylon 66 short fiber in the rubber composition is preferably 15 parts by mass or more and 25 parts by mass or less, and more preferably 18 parts by mass or more and 22 parts by mass or less, with respect to 100 parts by mass of the rubber component.

The short fibers 14 preferably have a fiber length of 1.0mm or more and 5.0mm or less, and more preferably 2.0mm or more and 4.0mm or less, from the viewpoint of obtaining excellent wear resistance of the power transmission surface. The fiber diameter of the short fibers 14 is preferably 5.0 μm or more and 30.0 μm or less, and more preferably 10.0 μm or more and 20.0 μm or less, from the viewpoint of obtaining excellent abrasion resistance of the power transmission surface. The aspect ratio of the short fiber 14, that is, the ratio of the fiber length to the fiber diameter, is 100 or more, and from the viewpoint of obtaining excellent abrasion resistance of the power transmission surface, the aspect ratio of the short fiber 14 is preferably 150 or more, more preferably 200 or more, and further preferably 300 or less.

From the viewpoint of obtaining excellent abrasion resistance of the power transmission surface, it is preferable that the rubber component of the rubber composition forming the compression rubber layer 11 is crosslinked with an organic peroxide. Examples of the organic peroxide include: dicumyl peroxide, 1, 3-bis (t-butylperoxyisopropyl) benzene, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, and the like. Preferably, the organic peroxide contains one or more of the above. In this case, the organic peroxide is blended in the uncrosslinked rubber composition before crosslinking of the rubber composition, but the blending amount of the organic peroxide is, for example, 1 part by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the rubber component. The rubber composition forming the compression rubber layer 11 may be one in which the rubber component is crosslinked with sulfur, or one in which the rubber component is crosslinked with both an organic peroxide and sulfur.

In the case where the rubber component of the rubber composition forming the compression rubber layer 11 is crosslinked with an organic peroxide, the rubber component in the rubber composition may be crosslinked with a co-crosslinking agent from the viewpoint of obtaining excellent abrasion resistance of the power transmission surface. Examples of the co-crosslinking agent include: trimethylolpropane trimethacrylate, N' -m-phenylene bismaleimide, zinc methacrylate, triallyl isocyanurate, ethylene glycol dimethacrylate, liquid polybutene, etc. Preferably, the co-crosslinking agent contains one or two or more of the above. The co-crosslinking agent is blended in the uncrosslinked rubber composition before crosslinking of the rubber composition, but the blending amount of the co-crosslinking agent is preferably 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the rubber component.

From the viewpoint of improving the adhesion with the short fibers and obtaining excellent wear resistance of the power transmission surface, it is preferable that the co-crosslinking agent contains N, N' -m-phenylene bismaleimide. Preferably, the amount of N, N' -m-phenylene bismaleimide as a co-crosslinking agent blended in the uncrosslinked rubber composition before crosslinking of the rubber composition is 3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component.

From the viewpoint of improving the elastic modulus, it is preferable that zinc methacrylate is contained in the co-crosslinking agent. Preferably, the amount of zinc methacrylate as the co-crosslinking agent blended in the uncrosslinked rubber composition before crosslinking of the rubber composition is 5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component.

Preferably, the co-crosslinking agent contains N, N' -m-phenylene bismaleimide and zinc methacrylate at the same time. In the case where N, N '-m-phenylene bismaleimide and zinc methacrylate are used together in the co-crosslinking agent, it is preferable that the amount of N, N' -m-phenylene bismaleimide blended in the uncrosslinked rubber composition before crosslinking of the rubber composition is smaller than the amount of zinc methacrylate blended in the uncrosslinked rubber composition before crosslinking of the rubber composition. Preferably, the amount of N, N' -m-phenylene bismaleimide blended is 3 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the rubber component; the blending amount of zinc methacrylate is preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the rubber component.

The rubber composition forming the compression rubber layer 11 may contain, for example, a vulcanization accelerator, a processing aid, an antioxidant, a reinforcing agent such as carbon black, a plasticizer, and the like as other rubber compounding agents.

The tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer 11 is 15.0MPa or more, but from the viewpoint of obtaining excellent wear resistance of the power transmission surface, it is preferably 18.0MPa or more and 40.0MPa or less, and more preferably 20.0MPa or more and 35.0MPa or less. The tensile yield stress in the present application is determined as follows. First, an elongated rubber sheet S (for example, about 17mm in width) is cut out from a portion of the compression rubber layer 11 on the outer peripheral side than the position corresponding to the tooth bottom of the lower tooth forming portion 11a as indicated by the broken line in fig. 1B and 1C, and the longitudinal direction of the rubber sheet S shown in fig. 4A is the belt length direction, i.e., the direction 90 degrees from the grain direction. Next, as shown by the broken line in fig. 4A, a long sample T (for example, 7mm in width) is cut out from the long rubber sheet S, and the longitudinal direction of the sample T is the tape width direction, that is, the grain direction. According to Japanese Industrial Standard JISK 7161-1: 2014, a tensile test in which the sample T is stretched at an ambient temperature of 25 ℃ at a speed of 500mm/min in the longitudinal direction is carried out, and as shown in FIG. 4B, the tensile yield stress is finally determined from the obtained stress-strain curve.

The binder rubber layer 12 and the tension rubber layer 13 are also formed of a rubber composition. Various rubber compounding agents are compounded in a rubber component and kneaded to form an uncrosslinked rubber composition, and the uncrosslinked rubber composition is heated and pressurized to crosslink the rubber component with a crosslinking agent, thereby obtaining a rubber composition. The adhesion rubber layer 12 and the tension rubber layer 13 may be formed of the same rubber composition as the compression rubber layer 11 or may be formed of a different rubber composition from the compression rubber layer 11.

The core wire 20 is embedded in the middle portion in the thickness direction of the adhesion rubber layer 12 of the V-belt body 10, and the core wire 20 is formed in a spiral having a pitch in the belt width direction. The core wire 20 is woven from, for example, twisted yarn. Examples of the fiber material forming the core wire 20 include polyester fiber and aramid fiber. The outer diameter of the core wire 20 is, for example, 0.7mm to 1.3 mm. In order to make the core wire 20 have adhesiveness to the adhesive rubber layer 12, it is preferable that one or two or more of the following adhesion treatments be performed on the core wire 20 before the forming process is performed. Namely: the adhesive agent is prepared by an adhesive treatment in which the core wire 20 is immersed in a base treatment agent containing an epoxy compound or an isocyanate compound and then heated, an adhesive treatment in which the core wire 20 is immersed in an RFL aqueous solution and then heated, and an adhesive treatment in which the core wire 20 is immersed in a rubber paste and then dried.

The inner reinforcing cloth 30 is provided to cover the inner peripheral surface of the compression rubber layer 11 of the V-belt body 10. The inner reinforcing fabric 30 is woven from woven fabric, knitted fabric, nonwoven fabric, or the like. Examples of the fiber material forming the inner reinforcing fabric 30 include: nylon fibers, polyester fibers, cotton, aramid fibers, and the like. The thickness of the inner reinforcing fabric 30 is, for example, 0.1mm to 1.0 mm. In order to make the inner reinforcing fabric 30 have adhesiveness to the compression rubber layer 11, it is preferable that one or two or more of the following adhesion treatments are performed on the inner reinforcing fabric 30 before the molding process. Namely: the adhesive treatment is performed by dipping the inner reinforcing fabric 30 in a base treatment agent containing an epoxy compound or an isocyanate compound and then heating, the adhesive treatment is performed by dipping the inner reinforcing fabric 30 in an RFL aqueous solution and then heating, the adhesive treatment is performed by dipping the inner reinforcing fabric 30 in a rubber paste and then drying, and the adhesive treatment is performed by applying a high-viscosity rubber paste to the surface of the inner reinforcing fabric 30 on the side to become the V-belt main body 10 and then drying. The lower teeth 15 are formed by covering the lower tooth forming portion 11a of the compression rubber layer 11 with the inner reinforcing cloth 30. The height of the lower teeth 15 is, for example, 3.4mm or more and 5.0mm or less, the width is, for example, 3.0mm or more and 6.0mm or less, and the pitch is, for example, 7.0mm or more and 11.0mm or less.

The outer reinforcing cloth 40 is provided to cover the outer peripheral surface of the tension rubber layer 13 of the V-belt body 10. The outer reinforcing fabric 40 is woven from woven fabric, knitted fabric, nonwoven fabric, or the like. Examples of the fiber material forming the outer reinforcing fabric 40 include: nylon fibers, polyester fibers, cotton, aramid fibers, and the like. The thickness of the outer reinforcing fabric 40 is, for example, 0.1mm to 1.0 mm. In order to make the outer reinforcing fabric 40 have adhesiveness to the tension rubber layer 13, it is preferable that one or two or more of the following adhesion treatments are performed on the outer reinforcing fabric 40 before the forming process. Namely: the adhesive treatment is performed by dipping the outer reinforcing fabric 40 in a base treatment agent containing an epoxy compound or an isocyanate compound and then heating, the adhesive treatment is performed by dipping the outer reinforcing fabric 40 in an RFL aqueous solution and then heating, the adhesive treatment is performed by dipping the outer reinforcing fabric 40 in a rubber paste and then drying, and the adhesive treatment is performed by applying a highly viscous rubber paste to the surface of the outer reinforcing fabric 40 on the side to become the V-belt main body 10 and then drying.

The toothed V belt B according to the above embodiment can be manufactured by a known method.

In the above embodiment, the toothed V-belt B having only the lower teeth 15 has been described, but the present invention is not particularly limited thereto as long as it is a friction drive belt having a power transmission surface formed of a rubber composition, and may be, for example, a double-toothed V-belt, a toothless trimmed V-belt, a V-ribbed belt, a flat belt, or the like.

Examples

(tooth V belt)

Toothed V belts of examples 1 to 5 and comparative examples 1 to 4 were produced. Table 1 shows the compounding ratios of the rubbers used in the examples and comparative examples.

< example 1 >

EPDM-1 (52 mass% ethylene, 7.7 mass% ENB and 27ML Mooney viscosity, manufactured by T7241 JSR) as a rubber component₁₊₄(125 ℃) were charged into the mixing chamber of a closed Banbury mixer for plastication. Then, to 100 parts by mass of the rubber component, 5 parts by mass of zinc oxide (zinc oxide 3 made by sakai chemical industry corporation), 1 part by mass of stearic acid (LUNAC queen corporation) as a processing aid, 50 parts by mass of FEF carbon black (SEAST SO east sea carbon corporation) as a reinforcing agent, 5 parts by mass of oil (SUNPAR 2280 japan sun oil corporation) as a plasticizer, N' -m-phenylene bismaleimide (VULNOC PM large interior emerging chemical corporation) as a co-crosslinking agent, 7.4 parts by mass (effective component 2.96 parts by mass) of an organic peroxide (perrexa 25B-40 japan oil company purity, 40% by mass) as a crosslinking agent, and 22.5 parts by mass of polyphenylene para-phenylene terephthalamide (KELVAR short fiber corporation, fiber length 3.5mm, fiber diameter 12.0 μm, aspect ratio 292) were kneaded. Then, a compression rubber layer was formed from the obtained uncrosslinked rubber composition, and a toothed V belt having the compression rubber layer was produced and designated as example 1. With respect to the toothed V belt of example 1, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 22.8 MPa.

The adhesion rubber layer and the tension rubber layer are formed of other EPDM rubber compositions. The core yarn is made of twisted yarn made of polyester fiber. The inner reinforcing cloth and the outer reinforcing cloth are woven from woven cloth woven from nylon 66 fibers.

The toothed V-belt of example 1 had a belt length (center circumference of the core wire) of 717.5mm, a maximum belt width on the outer circumference side of 19.4mm, a minimum belt width on the inner circumference side of 14.7mm, a maximum belt thickness of 9.5mm (2.0 mm on the outer circumference side from the center of the core wire and 7.5mm on the inner circumference side), and an included angle formed between both side surfaces of 30 °. The thickness of the adhesion rubber layer is 1.5mm, the outer diameter of the core wire is 1.0mm, the distance in the width direction of the core wire is 1.15mm, and the thickness of the outer side reinforcing cloth and the inner side reinforcing cloth is 0.66 mm. The height of the lower teeth is 4.1mm, the setting distance is 7.5mm, the curvature of the tooth tops is 2.2mm, and the curvature of the tooth bottoms is 1.0 mm.

< example 2 >

A toothed V belt was produced in the same manner as in example 1 except that 22 parts by mass of a copolymer p-phenylene-3, 4' -oxydiphenylene terephthalamide short fiber (3.0 mm in fiber length, 12.5 μm in fiber diameter, 240 in aspect ratio) as a p-aramid short fiber was blended as a rubber component forming the compression rubber layer per 100 parts by mass of the rubber component, and this was designated as example 2. With respect to the toothed V belt of example 2, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 30.3 MPa.

< example 3 >

A toothed V belt was produced in the same manner as in example 1 except that 22 parts by mass of meta-aramid short fiber (fiber length 3.0mm, fiber diameter 14.2 μm, aspect ratio 211) was blended as a short fiber to 100 parts by mass of the rubber component of the rubber composition forming the compression rubber layer, and this was designated as example 3. With respect to the toothed V belt of example 3, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 24.2 MPa.

< example 4 >

A toothed V belt was produced in the same manner as in example 1 except that 18 parts by mass of nylon 66 short fibers (LEONA 66 asa chemical) having a fiber length of 3.0mm, a fiber diameter of 27.3 μm and an aspect ratio of 110 were blended as short fibers with 100 parts by mass of the rubber component forming the compression rubber layer, and this was designated as example 4. With respect to the toothed V belt of example 4, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 24.1 MPa.

< example 5>

A toothed V belt was produced in the same manner as in example 1 except that the rubber composition forming the compression rubber layer was prepared by blending 20 parts by mass of zinc methacrylate (ACTOR ZMA available from kaiko chemical industries, inc.) as a co-crosslinking agent with 100 parts by mass of the rubber component, 5.8 parts by mass of copolymerized p-phenylene-3, 4' -oxydiphenylene terephthalamide short fiber as a p-aramid short fiber as a short fiber with 100 parts by mass of the rubber component, and 19.1 parts by mass of nylon 66 short fiber with 100 parts by mass of the rubber component, and this was designated as example 5. With respect to the toothed V belt of example 5, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 30.1 MPa.

< comparative example 1 >

A toothed V belt was produced in the same manner as in example 3 except that a rubber composition for forming a compression rubber layer was used, and the aspect ratio was 82, since meta-aramid short fiber having a fiber diameter of 36.4 μm, and this was designated as comparative example 1. With respect to the toothed V belt of comparative example 1, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 9.2 MPa.

< comparative example 2 >

A toothed V belt was produced in the same manner as in example 4 except that nylon 66 short fibers having a fiber length of 1.0mm were used as the rubber composition forming the compression rubber layer, and therefore the aspect ratio was 37, and this was designated as comparative example 2. With respect to the toothed V belt of comparative example 2, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 10.7 MPa.

< comparative example 3 >

EPDM-2 (ethylene content: 58% by mass, ENB content: 4.5% by mass, Mooney viscosity: 19.5ML, manufactured by EP123 JSR) was used for the rubber composition for forming the compression rubber layer₁₊₄(125 c)) as a rubber component, 16 parts by mass of a meta-aramid short fiber was added to 100 parts by mass of the rubber component, and the other points were the same as in example 3, and a toothed V belt was produced and designated as comparative example 3. With respect to the toothed V belt of comparative example 3, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 14.3 MPa.

< comparative example 4 >

A toothed V belt was produced in the same manner as in example 3 except that N, N' -m-phenylene bismaleimide as a co-crosslinking agent was not blended in the rubber composition forming the compression rubber layer and the blending amount of the meta-aramid short fiber was 21 parts by mass with respect to 100 parts by mass of the rubber component, and this was designated as comparative example 4. With respect to the toothed V belt of comparative example 4, the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition forming the compression rubber layer was 14.6 MPa.

[ TABLE 1 ]

< Belt run test >

Fig. 5 shows a pulley arrangement of the belt running tester 50.

The belt running test machine 50 has a driving pulley 51 having a pulley diameter of 52mm and a driven pulley 52 having a pulley diameter of 125mm movably provided on the right side of the driving pulley 51. The driving pulley 51 and the driven pulley were made of an aluminum alloy (ADC12), and had an arithmetic surface roughness (Ra) of 0.5mm and a V angle of 28 °.

In the toothed V-belts B of examples 1 to 5 and comparative examples 1 to 4, the shafts of the driven pulleys 52 were pulled with a load of 1176N by winding them around the driving pulley 51 and the driven pulleys 52, respectively, and then the driving pulley 51 was rotated at 6400rpm to run the toothed V-belt B for 48 hours. Then, the mass change rate of the belt mass change amount before and after the belt running with respect to the belt mass before the belt running was calculated.

(test results)

The test results are shown in table 1.

According to Table 1, the cases of examples 1 to 5 are: a rubber composition for forming a power transmission surface, wherein short fibers having an aspect ratio of 100 or more are dispersed in a rubber component mainly composed of EPDM having a diene content of 6.0 mass% or more in a belt width direction in an oriented manner, and the tensile yield stress in the belt width direction at 25 ℃ of the rubber composition is 15.0MPa or more. The cases of comparative examples 1 and 2 were: the aspect ratio of the short fiber is less than 100 and the tensile yield stress of the rubber composition in the direction of the belt width at 25 ℃ is less than 15.0Mpa, in the case of comparative example 3: the diene content is less than 6.0 mass% and the tensile yield stress in the belt width direction of the rubber composition at 25 ℃ is less than 15.0Mpa, in the case of comparative example 4: the tensile yield stress of the rubber composition in the direction of the belt width at 25 ℃ is less than 15.0 MPa. According to table 1, the belts of examples 1 to 5 had lower mass change rates before and after running than those of comparative examples 1 to 4. This demonstrates that the power transmission surfaces of examples 1 to 5 have excellent wear resistance.

Industrial applicability-

The present invention relates to a friction transmission belt.

-description of symbols-

B tooth V belt (Friction transmission belt)

S rubber sheet

T specimen

10V belt body

11 compression rubber layer

11a lower teeth forming part

12 bonded rubber layer

13 tensile rubber layer

14 short fiber

15 lower teeth

20 core wire

30 inside reinforcing cloth

40 outside reinforcing cloth

50-belt running tester

51 driving pulley

52 from the pulley.