Friction transmission belt

Abstract

To provide a friction transmission belt 2 capable of improving friction wear resistance characteristics.SOLUTION: The frictional power transmission belt 2 of the present invention includes a compression rubber layer 10 constituting a contact portion with a pulley. The compression rubber layer 10 includes a rubber layer body 12 formed of a crosslinked product of a rubber composition. The rubber layer body 12 has an acetone extract content of 5.0% by mass or less, the acetone extract content being determined by acetone extraction in accordance with JISK6229:2015.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a friction power transmission belt. This application claims priority from Japanese Application No. 2023-097420, filed on June 14, 2023, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Conventionally, as a means for transmitting rotational power from an engine, motor, etc., a method has been widely used in which pulleys are fixed to the rotating shafts of the driving and driven sides, and a friction transmission belt such as a V-ribbed belt is stretched across each pulley.

[0003] BACKGROUND ART It is known that in a friction transmission belt (hereinafter referred to as a transmission belt), the pulley contact surface is covered with a covering fabric in order to control the friction coefficient of the contact portion with the pulley (for example, Patent Document 1 listed below). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 193881 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, a serpentine drive system in which a single V-ribbed belt is wound around three or more pulleys, including a crankshaft pulley (drive ribbed pulley), a power steering pulley, and an air conditioning pulley (driven ribbed pulley), is widely used as a belt transmission device for driving automobile accessories. As automobiles become more sophisticated, further improvements in the friction and wear resistance of V-ribbed belts are required.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a friction transmission belt that can achieve improved friction and wear resistance based on an idea different from conventional ones. [Means for solving the problem]

[0007] (1) The friction drive belt of the present invention is a friction drive belt having a compressed rubber layer that forms a contact portion with a pulley, wherein the compressed rubber layer has a rubber layer main body made of a cross-linked rubber composition, and the acetone extractable content of the rubber layer main body is 5.0 mass % or less as determined by acetone extraction in accordance with JIS K6229:2015.

[0008] In the above friction transmission belt, the amount of solvent-extractable components contained in the rubber layer main body is maintained at an appropriate level. The rubber layer main body can effectively suppress the occurrence of adhesive wear caused by solvent-extractable components. The wear resistance of the rubber layer main body is improved. As a result, a stable contact state between the compressed rubber layer including the rubber layer main body and the pulley is maintained. The friction transmission belt can exhibit stable friction and wear resistance characteristics. The friction transmission belt can achieve improved friction and wear resistance characteristics.

[0009] (2) Preferably, in the friction transmission belt, the compressed rubber layer further includes a fibrous member layer laminated on the rubber layer main body, the fibrous member layer including a woven fabric, and the fibrous member contacting the pulley, thereby achieving further improvement in friction and wear resistance.

[0010] (3) Preferably, in the friction transmission belt, the fibrous member layer further includes a rubber member present in gaps between the fibrous members, and the rubber member is made of a crosslinked product of the rubber composition that has permeated the gaps. In this case, friction and wear resistance is further improved.

[0011] (4) Preferably, in the friction transmission belt, the rubber member contacts the pulley, which further improves the friction and wear resistance.

[0012] (5) Preferably, in the friction transmission belt, the rubber composition contains a raw rubber component, and the raw rubber component contains an ethylene-α-olefin elastomer as a main component. In this case, further improvement in friction and wear resistance is achieved.

[0013] (6) Preferably, the friction transmission belt is a V-ribbed belt. A V-ribbed belt having the above-described compressed rubber layer further improves the friction and wear resistance. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a friction transmission belt that can achieve improved friction and wear resistance. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram schematically illustrating a portion of a friction transmission belt according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing an example of a cross-linking device. [Figure 3A] 2A to 2C are diagrams illustrating a method for manufacturing the friction transmission belt shown in FIG. [Figure 3B] 2A to 2C are diagrams illustrating a method for manufacturing the friction transmission belt shown in FIG. [Figure 4] 3A and 3B are diagrams illustrating an example of a fibrous member constituting a fibrous member layer. [Figure 5] FIG. 4 is a conceptual diagram illustrating a surface state of a fibrous material layer. [Figure 6] FIG. 10 is a diagram showing the pulley layout of a belt running test machine for evaluating water-injected power transmission capacity. [Figure 7] FIG. 10 is a diagram showing the pulley layout of a belt running test machine for a durability test. BEST MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments described below.

[0017] (friction transmission belt) 1 shows an example of a friction power transmission belt 2 according to one embodiment of the present invention. The friction power transmission belt 2 is a V-ribbed belt. The V-ribbed belt 2 is used, for example, in an accessory drive belt transmission device provided in the engine compartment of an automobile.

[0018] The V-ribbed belt 2 is an endless belt. The V-ribbed belt 2 has a belt circumference of, for example, 700 mm or more and 3000 mm or less. The belt width is, for example, 10 mm or more and 36 mm or less. The belt thickness is, for example, 3.5 mm or more and 5.0 mm or less.

[0019] The V-ribbed belt 2 includes a belt body 4 and a plurality of ribs 6 located on the inner circumferential side of the belt body 4. The belt body 4 extends in the belt length direction. A plurality of ribs 6 are arranged in the belt width direction. Each rib 6 is a protrusion that hangs inward from the inner peripheral surface of the belt body 4. The ribs 6 taper inward. The ribs 6 have a cross-sectional shape that is approximately an inverted triangle. The ribs 6 are also called V-ribs.

[0020] The rib height of the ribs 6 is, for example, 2.0 mm or more and 3.0 mm or less. The width between the base ends is, for example, 1.0 mm or more and 3.0 mm or less. The number of ribs 6 is, for example, 3 or more and 10 or less. The number of ribs 6 in the V-ribbed belt 2 shown in FIG. 1 is 6. The inner peripheral side of the V-ribbed belt 2 comes into contact with a pulley such as a drive pulley or a driven pulley. Ribs 6 are provided on the inner peripheral side of the V-ribbed belt 2. The ribs 6 come into contact with the pulley. Hereinafter, the specific configuration of the friction power transmission belt 2 according to one embodiment of the present invention will be described using this V-ribbed belt 2 as an example.

[0021] The friction transmission belt 2 includes a compressed rubber layer 10, an adhesive rubber layer 20, and a back reinforcement fabric 30. The friction transmission belt 2 is configured by combining the compressed rubber layer 10, the adhesive rubber layer 20, and the back reinforcement fabric 30.

[0022] The compressed rubber layer 10 is located on the inner peripheral side of the belt. The back reinforcing fabric 30 is located on the outer peripheral side of the belt. The adhesive rubber layer 20 is located between the compressed rubber layer 10 and the back reinforcing fabric 30. The compressed rubber layer 10, adhesive rubber layer 20, and back reinforcing fabric 30 are arranged in this order in the thickness direction of the belt.

[0023] The compressed rubber layer 10 extends in the length direction of the belt. The compressed rubber layer 10 comes into contact with the pulley. The compressed rubber layer 10 forms the contact portion with the pulley. When the friction transmission belt 2 is a V-ribbed belt, the ribs 6 are provided on the inner circumferential side of the V-ribbed belt 2. In the V-ribbed belt 2, the ribs 6 are formed in the compressed rubber layer .

[0024] The compressed rubber layer 10 includes a rubber layer body 12. The rubber layer body 12 is formed using a rubber composition. The rubber layer body 12 of the compressed rubber layer 10 is also called a compressed rubber layer body.

[0025] A rubber composition is produced by mixing a raw rubber component with various compounding agents. The rubber composition contains the raw rubber component and various compounding agents.

[0026] Examples of compounding agents that can be contained in the rubber composition include crosslinking agents such as sulfur and organic peroxides, vulcanization accelerators such as zinc oxide, co-crosslinking agents, antioxidants, processing aids such as stearic acid, softeners such as process oil, plasticizers such as dioctyl phthalate (DOP), reinforcing agents such as carbon black, and fillers.

[0027] The rubber layer main body 12 is made of a cross-linked product of the rubber composition. In other words, the rubber layer main body 12 is a cross-linked rubber produced using the rubber composition. The cross-linked rubber is obtained by pressurizing and heating the rubber composition in a mold and cross-linking the raw rubber components with a cross-linking agent as a compounding agent.

[0028] Examples of raw rubber components contained in the rubber composition for the rubber layer main body 12 include ethylene-α-olefin elastomers such as ethylene-propylene-diene terpolymer (EPDM), ethylene-propylene copolymer (EPM), ethylene-butene copolymer (EBM), and ethylene-octene copolymer (EOM); chloroprene rubber (CR); chlorosulfonated polyethylene rubber (CSM); and hydrogenated acrylonitrile rubber (H-NBR). The rubber composition preferably uses one or more of these as raw rubber components, and more preferably contains an ethylene-α-olefin elastomer. In this case, the raw rubber component preferably contains an ethylene-α-olefin elastomer as the main component.

[0029] The raw rubber component containing an ethylene-α-olefin elastomer as a main component means that the amount of ethylene-α-olefin elastomer contained in the raw rubber component is 50% by mass or more of the total amount of the raw rubber component.

[0030] When the main component of the raw rubber component is an ethylene-α-olefin elastomer, the amount of the ethylene-α-olefin elastomer contained in the raw rubber component is preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more of the total amount of the raw rubber component. It is particularly preferable that the raw rubber component is an ethylene-α-olefin elastomer. EPDM is preferably used as the ethylene-α-olefin elastomer.

[0031] When the raw rubber component is mainly composed of an ethylene-α-olefin elastomer, the rubber composition preferably contains process oil in an amount of preferably 0.1 to 40 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the raw rubber component.

[0032] Examples of process oils include paraffinic oils, naphthenic oils, and aromatic oils, and the rubber composition may contain one or more of these as the process oil. When EPDM is used as the ethylene-α-olefin elastomer, paraffin-based oil is preferred as the process oil.

[0033] Examples of cross-linking agents include sulfur and organic peroxides such as dicumyl peroxide. When the main component of the raw rubber component is an ethylene-α-olefin elastomer, the rubber composition preferably contains at least sulfur as a cross-linking agent. In this case, the amount of sulfur blended is preferably 0.5 to 5 parts by mass per 100 parts by mass of the raw rubber component.

[0034] As shown in Fig. 1, a fiber member layer 14 is formed on the inner circumferential surface of the rubber layer main body 12. The compressed rubber layer 10 shown in Fig. 1 is formed of the rubber layer main body 12 and the fiber member layer 14. The compressed rubber layer 10 of the friction transmission belt 2 may further include the fiber member layer 14.

[0035] The fibrous material layer 14 forms the inner circumferential surface of the friction power transmission belt 2. The thickness of the fibrous material layer 14 is, for example, not less than 0.1 mm and not more than 1.5 mm.

[0036] 1 covers the entire inner circumferential surface of the rubber layer main body 12. The fiber material layer 14 is laminated on the inner circumferential surface of the rubber layer main body 12. The compressed rubber layer 10 may be configured so that the fiber material layer 14 covers a portion of the inner circumferential surface of the rubber layer main body 12.

[0037] The fiber material layer 14 forms the surface of the compressed rubber layer 10. In the friction power transmission belt 2, the fiber material layer 14 comes into contact with the pulley. The surface of the fiber material layer 14 is a contact surface 14a that comes into contact with the pulley. The fiber material layer 14 has the contact surface 14a that comes into contact with the pulley. As described above, in the V-ribbed belt 2, the ribs 6 are formed on the compression rubber layer 10, and the ribs 6 come into contact with the pulley. The surface of the ribs 6 is formed of a fiber member layer 14.

[0038] The fibrous material layer 14 includes a fibrous material. The fibrous material is made of a fabric. Examples of the fabric include woven fabric and knitted fabric. Examples of weaves of woven fabrics include plain weave, twill weave, satin weave, and variations thereof. Examples of knitted fabrics include plain knit, rib knit, purl knit, and other variations in the weft, and single Denbigh knit, single Van Dyke knit, and other variations in the warp. From the viewpoint of being able to uniformly cover the rubber layer main body 12, the fiber member is preferably a highly stretchable knitted fabric.

[0039] When the fibrous member is a woven fabric, warp and weft yarns are used to form the fibrous member. When the fibrous member is a knitted fabric, knitting yarns are used to form the fibrous member. Examples of fibers constituting the yarns used to form woven or knitted fabrics include natural fibers such as cellulose fibers, wool, and silk, and synthetic fibers such as polyurethane fibers, aliphatic polyamide fibers (nylon 66 fibers), aromatic polyamide fibers (para- and meta-based), polyester fibers, acrylic fibers, and polyvinyl alcohol fibers. Woven or knitted fabrics may be made of one type of fiber or two or more types of fibers. From the viewpoint of having good water absorption performance, the fibers constituting the fibrous member are preferably cellulosic fibers.

[0040] When forming the fiber material layer 14, a fiber material that has been subjected to an adhesive treatment may be used, or a fiber material that has not been subjected to an adhesive treatment may be used. Examples of adhesive treatments include a treatment in which a fiber material is immersed in an epoxy resin solution or an isocyanate resin solution and heated, a treatment in which a fiber material is immersed in an RFL aqueous solution and heated, and a treatment in which a fiber material is immersed in rubber cement and dried.

[0041] The adhesive rubber layer 20 extends in the longitudinal direction of the belt. The adhesive rubber layer 20 has a horizontally elongated rectangular cross section. The thickness of the adhesive rubber layer 20 is, for example, 1.0 mm or more and 2.5 mm or less.

[0042] The adhesive rubber layer 20 includes a rubber layer main body 22 and a core wire 24. The adhesive rubber layer 20 of this friction transmission belt 2 is composed of the rubber layer main body 22 and the core wire 24.

[0043] The rubber layer main body 22 of the adhesive rubber layer 20 is also called an adhesive rubber layer main body. The adhesive rubber layer main body 22 is made of a rubber composition. The adhesive rubber layer main body 22 is made of a cross-linked product of the rubber composition. In this friction transmission belt 2, the adhesive rubber layer main body 22 may be made of the same rubber composition as the rubber composition of the compressed rubber layer main body 12, or may be made of a rubber composition different from the rubber composition of the compressed rubber layer main body 12.

[0044] The cord 24 is located in the middle of the adhesive rubber layer 20 in the belt thickness direction. The cord 24 is covered with the rubber layer main body 22. The cord 24 extends in the belt length direction. As shown in Figure 1, in the cross section of the adhesive rubber layer 20, the cross sections of multiple cords 24 (hereinafter referred to as cord cross sections) are aligned in the belt width direction. In the adhesive rubber layer 20, one or more cords 24 are wound spirally at regular intervals in the belt width direction.

[0045] The core wires 24 are made of twisted yarns of polyamide fiber, polyester fiber, aramid fiber, polyamide fiber, etc. The diameter of the core wires 24 is, for example, 0.5 mm or more and 2.5 mm or less. The distance between adjacent core wire cross sections in the cross section of the adhesive rubber layer 20 is, for example, 0.05 mm or more and 0.20 mm or less.

[0046] The core wire 24 may be subjected to an adhesive treatment. Examples of adhesive treatments include immersion in an epoxy resin solution or an isocyanate resin solution followed by heating, immersion in an RFL aqueous solution followed by heating, and immersion in rubber cement followed by drying. It is preferable that the core wire 24 be subjected to one or more of these adhesive treatments.

[0047] The back reinforcing fabric 30 is made of, for example, a plain weave, twill weave, satin weave, knitted fabric, nonwoven fabric, or other fabric material using yarns such as cotton, polyamide fiber, polyester fiber, or aramid fiber. The thickness of the back reinforcing fabric 30 is, for example, 0.4 mm or more and 1.2 mm or less. To impart adhesion to the adhesive rubber layer 20, the back reinforcing fabric 30 may be subjected to an adhesion treatment in which it is immersed in an RFL aqueous solution and heated before molding, and / or an adhesion treatment in which rubber cement is coated on the outer circumferential surface of the adhesive rubber layer 20 and dried. The back reinforcing fabric 30 may be attached to the adhesive rubber layer 20 via a rubber layer (not shown).

[0048] In this friction power transmission belt 2, a back rubber layer (not shown) having a thickness of, for example, 0.4 mm to 0.8 mm may be used instead of the back reinforcing fabric 30. In this case, the texture of the woven fabric is preferably transferred to the surface of the back rubber layer in order to suppress noise generation during back drive. In order to suppress adhesion due to contact between the back surface of the belt and the flat pulley, the back rubber layer is preferably made of a rubber composition that is slightly harder than the adhesive rubber layer main body 22. When a back rubber layer is provided, this back rubber layer may be made of the same rubber composition as one or both of the compressed rubber layer main body 12 and the adhesive rubber layer main body 22, or may be made of a rubber composition different from either the compressed rubber layer main body 12 or the adhesive rubber layer main body 22. When the back rubber layer is made of a rubber composition different from that of the adhesive rubber layer main body 22, it is preferable that the back rubber layer be made of a rubber composition that is slightly harder than that of the adhesive rubber layer main body 22, in order to prevent adhesion caused by contact between the back surface of the belt and the flat pulley.

[0049] (Method of manufacturing friction transmission belt) Next, a method for manufacturing the friction transmission belt 2 will be described with reference to the drawings. The friction transmission belt 2 according to one embodiment of the present invention is manufactured by a conventionally known method. FIG. 2 is a diagram illustrating a cross-linking device 40 used in manufacturing a V-ribbed belt as the friction transmission belt 2. As shown in FIG.

[0050] The cross-linking device 40 includes a base 42, an expansion drum 44, and a mold 46. The expansion drum 44 is cylindrical. The expansion drum 44 is erected on the base 42. The mold 46 is cylindrical. The mold 46 is provided outside the expansion drum 44.

[0051] The expansion drum 44 has a drum body 48 and an expansion sleeve 50. Both the drum body 48 and the expansion sleeve 50 are cylindrical. The expansion sleeve 50 is located on the outside of the drum body 48. The expansion sleeve 50 is made of rubber. The expansion sleeve 50 is fitted onto the outer periphery of the drum body 48. The drum body 48 has a number of ventilation holes 48a. Each ventilation hole 48a connects the inside and outside of the drum body 48. Both ends of the expansion sleeve 50 are fixed by fixing rings 52. The fixing rings 52 seal the gaps between the drum body 48 and the ends of the expansion sleeve 50.

[0052] Although not shown, the cross-linking device 40 has a pressurizing means. The pressurizing means introduces pressure-adjusted air into the drum body 48. The air passes through the air vents 48a and is introduced between the drum body 48 and the expansion sleeve 50. The expansion sleeve 50 expands radially outward. This pressurizes the uncross-linked slab, which will be described later.

[0053] The mold 46 is detachable from the base 42. The mold 46 attached to the base 42 is provided concentrically on the outside of the expansion drum 44. The die 46 is a die used to manufacture the V-ribbed belt 2. A plurality of rib forming grooves 46a extending in the circumferential direction are provided on the inner peripheral surface of the die 46 to form the ribs 6 of the V-ribbed belt 2. The plurality of rib forming grooves 46a are arranged in parallel in the axial direction (groove width direction). Each rib forming groove 46a is formed so that its width narrows from the groove opening toward the groove bottom. The shape of the rib forming groove 46a corresponds to the shape of the rib 6.

[0054] Although not shown, the cross-linking device 40 includes a heating means and a cooling means for the mold 46. The temperature of the mold 46 is controlled by the heating means and the cooling means.

[0055] 3A and 3B are diagrams for explaining a method of manufacturing a V-ribbed belt as the friction transmission belt 2. FIG.

[0056] In the manufacturing method of the V-ribbed belt 2 according to the embodiment, first, the raw rubber components are mixed with the compounding ingredients, and then kneaded in a kneading machine such as a kneader or a Banbury mixer to obtain a rubber composition. The rubber composition is formed into a sheet by calendar molding or the like to prepare an uncrosslinked rubber sheet 12' for the rubber layer main body 12 of the compressed rubber layer 10. Similarly, an uncrosslinked rubber sheet 22' for the rubber layer main body 22 of the adhesive rubber layer 20 is also prepared. A fiber member 60 for the fiber member layer 14 and a back reinforcing cloth 30 are prepared, and an adhesive treatment is applied to the fiber member 60 or the back reinforcing cloth 30 as needed. In this manufacturing method, the fiber member 60 is formed into a cylindrical shape in advance. The back reinforcing cloth 30 may also be formed into a cylindrical shape in advance. A cord 24 is prepared, and an adhesive treatment is applied to the cord 24 as needed.

[0057] Next, the back reinforcing fabric 30 and the uncrosslinked rubber sheet 22' for the adhesive rubber layer main body 22 are wound in this order around a cylindrical drum (not shown) covered with a rubber sleeve. After the core wire 24 is spirally wound around the uncrosslinked rubber sheet 22', the uncrosslinked rubber sheet 22' for the adhesive rubber layer main body 22 and the uncrosslinked rubber sheet 12' for the compressed rubber layer main body 12 are further wound in this order. A cylindrical fiber member 60 is placed on the uncrosslinked rubber sheet 12' to obtain an uncrosslinked slab S'.

[0058] Next, the uncrosslinked slab S' is removed from the cylindrical drum together with the rubber sleeve 54. As shown in Fig. 3A, the uncrosslinked slab S' is placed on the inner peripheral surface side of the mold 46 together with the rubber sleeve 54. As a result, the uncrosslinked slab S' is set between the mold 46 and the expansion drum 44.

[0059] Next, the mold 46 is heated, and air is introduced through the air vents 48a between the drum body 48 of the expansion drum 44 and the expansion sleeve 50, as shown in FIG. 3B. The expansion sleeve 50 is expanded, and the uncrosslinked slab S' is pressed against the mold 46. The uncrosslinked rubber sheet 12' flows into the rib forming grooves 46a while stretching the fibrous member 60. The fibrous member 60, the uncrosslinked rubber sheet 12', the uncrosslinked rubber sheet 22', the cords 24, and the back reinforcing fabric 30 are integrated, and crosslinking of the raw rubber components of the uncrosslinked rubber sheets 12' and 22' progresses. As a result, a cylindrical belt slab S is formed. The belt slab S is a crosslinked product of the uncrosslinked slab S'. The forming temperature of the belt slab S is, for example, 100° C. or more and 180° C. or less. The forming pressure of the belt slab S is, for example, 0.5 MPa or more and 2.0 MPa or less. The forming time of the belt slab S is, for example, 10 minutes or more and 60 minutes or less.

[0060] Then, the belt slab S is taken out from the cross-linking device 40, and the belt slab S is cut into rings each having a predetermined number of ribs 6 and turned over, thereby obtaining the V-ribbed belt 2.

[0061] In order to improve the friction and wear resistance of the friction transmission belt 2 described above, the present inventors focused on the wear resistance of the rubber layer main body 12 of the compressed rubber layer 10 that comes into contact with the pulley. If the wear resistance of the rubber layer main body 12 is improved, the contact state between the compressed rubber layer 10 and the pulley is maintained stably, which contributes to improving the friction and wear resistance of the friction transmission belt 2.

[0062] As mentioned above, the rubber layer main body 12 is made of a cross-linked rubber composition. The cross-linked rubber composition contains various components, including unreacted components from the cross-linking reaction. These components include components that can be extracted with a solvent. The rubber composition contains liquid compounding agents such as plasticizers and softeners. For example, increasing the amount of liquid compounding agents increases the solvent extractable content of the cross-linked rubber. The solvent extractable content of the cross-linked rubber also increases when the raw rubber components contain a large amount of low-molecular-weight components.

[0063] The solvent-extractable components can move within the matrix of the cross-linked product. The solvent-extractable components may be closely related to the occurrence of adhesive wear. If the solvent-extractable components are closely related to the occurrence of adhesive wear, it is conceivable that the wear resistance of the rubber layer main body 12 will decrease if the rubber layer main body 12 contains a large amount of solvent-extractable components.

[0064] Therefore, based on the above-mentioned idea, the inventors conducted extensive research into the effect of solvent-extractable components on the abrasion resistance of the rubber layer main body 12 in order to improve the abrasion resistance of the rubber layer main body 12. As a result, they discovered that adjusting the solvent-extractable components of the rubber layer main body 12, rather than the amount of liquid compounding agent, is more effective in controlling the abrasion resistance of the rubber layer main body 12, and thus completed the present invention.

[0065] In the friction transmission belt 2 according to one embodiment of the present invention, in order to determine the amount of solvent-extractable components contained in the rubber layer main body 12, the acetone extractable content of the rubber layer main body 12 determined by acetone extraction in accordance with JIS K6229:2015 is used as the solvent extractable content. To measure the acetone extractables, a portion (approximately 3 g) of the rubber layer main body 12 from the compressed rubber layer 10 of the friction transmission belt 2 is sampled as a test piece. Using acetone as the extraction solvent, the test piece is subjected to Soxhlet extraction for 8 hours. The acetone extractables are determined according to Method A specified in JIS K6229:2015.

[0066] In this friction drive belt 2, the acetone extractable content of the rubber layer main body 12, as determined by acetone extraction in accordance with JIS K6229:2015, is 5.0 mass% or less. This maintains an appropriate amount of solvent-extractable components contained in the rubber layer main body 12. The rubber layer main body 12 can effectively suppress the occurrence of adhesive wear caused by solvent-extractable components. The wear resistance of the rubber layer main body 12 is improved. As a result, a stable contact state between the compressed rubber layer 10, including the rubber layer main body 12, and the pulley is maintained. The friction drive belt 2 can exhibit stable friction and wear resistance characteristics. The friction drive belt 2 can achieve improved friction and wear resistance characteristics.

[0067] In this friction transmission belt 2, from the viewpoint of more effectively improving the wear resistance of the rubber layer main body 12, the acetone extractables of the rubber layer main body 12 are preferably 4.9% by mass or less, and more preferably 4.1% by mass or less. From the viewpoint of improving the wear resistance, the lower the acetone extractables, the better, so no preferred lower limit is set.

[0068] The acetone extractables are controlled by adjusting the composition of the rubber composition, including the selection of raw rubber components. The acetone extractables in the target rubber composition without any liquid compounding ingredients correspond to the lower limit of the acetone extractables in the composition of the rubber composition.

[0069] As described above, the fiber material layer 14 includes a fiber material 60. FIG. 4 shows an example of the fiber material 60 that constitutes the fiber material layer 14. The fiber material 60 shown in FIG. 4 is a knitted fabric called plain knit or jersey knit. The knitted fabric is made by knitting a yarn 62 (knitting yarn). This forms stitches. The stitches are gaps that are created when the yarn 62 is knitted. Although not shown in the figure, woven fabric is made by combining threads (warp threads) and threads (weft threads). This creates a weave. The weave is the gap in the woven fabric. Thus, the fibrous member 60 has many gaps.

[0070] A large number of gap openings are present on the surface of the fibrous member 60. The portions indicated by the symbol S in Fig. 4 are the gaps of the fibrous member 60 shown in Fig. 4. The gap S penetrates the fibrous member 60. In the following description, for convenience of explanation, the gap S is represented as a cylindrical hole penetrating the fibrous member 60.

[0071] As described above, the compression rubber layer 10 includes the fibrous member layer 14, and this fibrous member layer 14 includes the fibrous member 60. The fibrous member 60 forms the skeleton of the fibrous member layer 14 that comes into contact with the pulley. The fibrous member 60 comes into contact with the pulley. As described above, numerous gaps S exist in the fibrous member 60. When liquid such as water exists between the compressed rubber layer 10 and the pulley, the numerous gaps S existing in the fibrous member 60 capture the liquid. This maintains stable contact between the compressed rubber layer 10 and the pulley. This friction transmission belt 2 can exhibit high water-injected power transmission performance. This friction transmission belt 2 can improve friction and wear resistance by further including a fibrous member layer 14 containing the fibrous member 60 in the compressed rubber layer 10.

[0072] As described above, in the method for producing the friction transmission belt 2, the uncrosslinked slab S' is pressed against the mold 46, and the uncrosslinked rubber sheet 12' flows into the rib forming grooves 46a while stretching the fibrous members 60. For example, as shown in FIG. 3B, a fibrous member 60 is laminated on an uncrosslinked rubber sheet 12', i.e., the rubber composition of the rubber layer main body 12. The rubber composition has fluidity. When the rubber composition presses the fibrous member 60, a portion of the rubber composition penetrates into the gaps S of the fibrous member 60. Thereafter, the raw rubber components of the rubber composition are crosslinked, and as shown in FIG. 3B, a rubber member 64 made of a crosslinked product of the rubber composition that has penetrated into the gaps S is formed in the gaps S of the fibrous member 60. The rubber member 64 stretches, threading through the gaps S of the fibrous member 60. The fibrous material layer 14 is made up of fibrous materials 60 and rubber materials 64 present in gaps S between the fibrous materials 60. The fibrous material layer 14 includes the rubber material 64 in addition to the fibrous materials 60.

[0073] The rubber members 64 function as anchors. The fiber members 60 are firmly bonded to the rubber layer main body 12. The fiber members 60 can continue to contribute to the water-injected power transmission ability of the friction power transmission belt 2. The fiber member layer 14 further includes the rubber members 64 present in the gaps S between the fiber members 60, so that the friction and wear resistance of the friction power transmission belt 2 can be further improved.

[0074] FIG. 5 schematically shows the surface state of the fiber material layer 14. As shown in FIG. As described above, numerous openings of the gaps S are present on the surface of the fiber material 60. In the method for producing the friction transmission belt 2, the rubber composition presses the fiber material 60, so that part of the rubber composition that has soaked into the gaps S seeps out onto the surface of the fiber material 60. The surface of the fiber material layer 14 is configured with a fiber portion 60a made of the fiber material 60 and a rubber portion 64a made of the rubber material 64. The surface of the fiber material layer 14, i.e., the contact surface 14a that comes into contact with the pulley, is equipped with the fiber portion 60a and the rubber portion 64a. The rubber member 64 forms part of the contact surface 14a.

[0075] The rubber member 64 comes into contact with the pulley. When adhesive wear occurs in the rubber member 64 due to this contact, adhesive wear debris is generated. The wear debris adheres to the fiber member 60. In particular, when the wear debris adheres to the gaps S of the fiber member 60 and blocks the gaps S, the liquid capturing function of the fiber member 60 decreases. The wear progresses gradually. It is expected that the water injection power transmission capacity of the friction power transmission belt 2 will gradually decrease.

[0076] However, the rubber member 64 is a cross-linked product of the rubber composition of the rubber layer main body 12 that has soaked into the gaps S of the fiber member 60. As described above, the acetone extractable content of the rubber layer main body 12 is 5.0 mass % or less. The rubber member 64 has excellent wear resistance. Even when the rubber member 64 comes into contact with a pulley, adhesive wear is unlikely to occur. Wear debris is effectively prevented from clogging the gaps S. The fiber member 60 can continue to exert its liquid capturing function. With this friction power transmission belt 2, deterioration of water-injected power transmission capacity due to use is significantly suppressed. Since the rubber member 64 present in the gap S of the fiber member 60 is a cross-linked product of the rubber composition of the rubber layer main body 12, even if this rubber member 64 comes into contact with the pulley, this friction transmission belt 2 can continue to maintain good water injection power transmission ability. This friction transmission belt 2 can further improve the friction and wear resistance characteristics.

[0077] As described above, in the method for producing the friction transmission belt 2, the rubber composition presses the fiber member 60, so that part of the rubber composition penetrates into the gaps S of the fiber member 60. While the rubber composition has a predetermined fluidity, the stronger the force with which the rubber composition presses the fibrous member 60, the longer the time the rubber composition presses the fibrous member 60, the higher the fluidity of the rubber composition, and the larger the size of the gaps S in the fibrous member 60, the greater the amount of rubber composition that seeps out to the surface. When a large amount of rubber composition has seeped out to the surface, the rubber portions 64a cover the gaps S. When a small amount of rubber composition has seeped out, the rubber portions 64a are formed inside the gaps S. If the rubber composition does not reach the openings, the rubber portions 64a will not be formed on the contact surface 14a. The proportion of the rubber portions 64a that occupy the contact surface 14a varies depending on the molding conditions, the fluidity of the rubber composition, the specifications of the fibrous member 60, and the like. The proportion of the rubber portions 64a that occupy the contact surface 14a is set appropriately according to the specifications of the friction transmission belt.

[0078] The surface state of the fiber material layer 14 shown in Fig. 5 is a state in which rubber portions 64a are formed in some of the gaps S of the fiber material 60 shown in Fig. 4. In Fig. 5, the gaps S where the rubber composition did not reach the openings and the rubber portions 64a were not formed are not shown as part of the fiber material 60a.

[0079] The proportion of the rubber portion 64a occupying the contact surface 14a (hereinafter referred to as the rubber occupied area ratio) can be obtained, for example, as follows. An observation sample including a portion of the surface is taken from the fiber member layer 14 of the V-ribbed belt 2. There is no particular limitation on the size of the surface to be sampled, but for example, an observation sample including a rectangular surface having a size of 5 mm in the belt longitudinal direction and 2 mm in the belt width direction is prepared. The observation sample is placed on the stage of a microscope (for example, Keyence's digital microscope "VHX-6000") and the surface is brought into focus. A slide glass is pressed against the observation sample from above, and an image of the surface of the fiber material layer 14 is taken. Based on the surface image taken, the area of ​​each rubber portion 64a included in the observation target area is measured by software built into the microscope. As a result, the ratio of the total area of ​​the rubber portions 64a to the area of ​​the entire observation target area is obtained as the rubber occupied area ratio. In measuring the rubber occupied area ratio, the load with which the slide glass presses the surface sample is appropriately set so as not to exceed 1 kg for a surface size of 5 mm × 2 mm, and this load is preferably set to about 500 g (more specifically, 450 g to 550 g). The rubber occupied area ratio thus obtained is preferably 3% or more and 50% or less, from the viewpoint of obtaining good friction and wear resistance properties.

[0080] Up to this point, a V-ribbed belt has been described as an embodiment of the friction transmission belt according to the present invention, but the friction transmission belt according to the embodiment of the present invention is not limited to this and may be a V-belt, a flat belt, etc. [Example]

[0081] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. Here, V-ribbed belts of Examples 1 to 6 and Comparative Examples 1 to 4 were produced and evaluated.

[0082] <Materials for fiber component layers> To form the fiber member layer, a knitted fabric was prepared as the fiber member. The knitted fabric used was a plain knit (plain knit) fabric made of urethane elastic yarn covered with 6-nylon yarn. The urethane elastic yarn had a fineness of 22 denier (24.4 dtex), and the 6-nylon yarn had a fineness of 78 denier (86.7 dtex) and 52 filaments. The knitted fabric had a wale density of 66 threads / 2.54 cm and a course density of 70 threads / 2.54 cm. The knitted fabric was 0.52 mm thick. As an adhesive treatment for this knitted fabric, the knitted fabric was immersed in an RFL aqueous solution and heated and dried to form an RFL coating on the surface of the knitted fabric. The RFL aqueous solution was prepared as follows. Resorcinol (R) and formalin (F) were mixed, and an aqueous sodium hydroxide solution was added and stirred to obtain an RF precondensate (R / F molar ratio = 1 / 1.5). VP latex (L) was then mixed with the RF precondensate to give an RF / L mass ratio of 1 / 8, and water was added to adjust the solid concentration to 20%, followed by stirring for 24 hours to obtain an RFL aqueous solution.

[0083] <Material for the main body of the compressed rubber layer> The following two types of EPDM were prepared as raw rubber components. EPDM1 (product name "EP 123" manufactured by JSR) EPDM2 (DOW CHEMICAL's product name "Nordel 4640") The compounding ingredients prepared were carbon black (trade name "Asahi #60" manufactured by Asahi Carbon Co., Ltd.), process oil (trade name "Sunflex 2280" manufactured by Japan Sun Oil Co., Ltd.), zinc oxide (trade name "Zinc Oxide Type 2" manufactured by Sakai Chemical Industry Co., Ltd.), stearic acid (trade name "Stearic Acid" manufactured by Kao Corporation or "Beads Stearic Acid Camellia" manufactured by NOF Corporation), vulcanization accelerator A (trade name "Nocceler MSA-G" manufactured by Ouchi Shinko Chemical Co., Ltd.), vulcanization accelerator B (trade name "Sunceler EM2" manufactured by Sanshin Chemical Industry Co., Ltd.), and sulfur (trade name "Oil Sulfur" manufactured by Hosoi Chemical Industry Co., Ltd.). A rubber composition was prepared by blending and kneading each material in the amounts shown in Table 1. The rubber composition was formed into a sheet having a thickness of 0.7 mm using a roll.

[0084] [Table 1]

[0085] <Materials for the adhesive rubber layer> EPDM (manufactured by JSR Corporation under the trade name "EP123") was used as a raw rubber component. 100 parts by mass of this raw rubber component was blended with 50 parts by mass of carbon black (manufactured by Asahi Carbon Co., Ltd. under the trade name "Asahi #60"), 8 parts by mass of process oil (manufactured by Japan Sun Oil Co., Ltd. under the trade name "Sunflex 2280"), 1 part by mass of stearic acid (manufactured by Kao Corporation under the trade name "Stearic Acid" or NOF Corporation under the trade name "Beads Stearic Acid Camellia"), 5 parts by mass of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd. under the trade name "Zinc Oxide Type 2"), 5 parts by mass of zinc methacrylate (manufactured by Kawaguchi Chemical Industry Co., Ltd. under the trade name "Actor ZMA"), 1 part by mass of a vulcanization accelerator (manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Nocceler MSA-G"), 3 parts by mass of a vulcanization accelerator (manufactured by Sanshin Chemical Industry Co., Ltd. under the trade name "Sunceler EM2"), and 1.5 parts by mass of sulfur (manufactured by Hosoi Chemical Industry Co., Ltd. under the trade name "Oil Sulfur") to prepare a rubber composition. The rubber composition was formed into a sheet having a thickness of 0.45 mm using a roll.

[0086] <Materials for the core wire> As the material for the core wire, a twisted yarn of polyester fiber was prepared, which was immersed in an RFL aqueous solution and then subjected to an adhesive treatment by heating and drying.

[0087] <Material for back reinforcement fabric> The back reinforcing fabric was prepared by immersing a woven fabric made of a cotton-polyester blended yarn in an RFL aqueous solution and then subjecting it to a bonding treatment of heating and drying.

[0088] [Example 1] A V-ribbed belt having a width of 21.36 mm (6 V-ribs) and a circumferential length of 1210 mm was produced using the same configuration as the above embodiment, and using the rubber composition of Example 1 shown in Table 1 as the compressed rubber layer main body material, and the above-mentioned fiber members, compressed rubber layer main body material, adhesive rubber layer main body material, core wire, and back reinforcing fabric as described above, using the manufacturing method described with reference to Figures 2 to 3B. This was the V-ribbed belt of Example 1.

[0089] [Examples 2 to 6 and Comparative Examples 1 to 4] V-ribbed belts (width = 21.36 mm (number of V-ribs: 6), circumference = 1210 mm) of Examples 2 to 6 and Comparative Examples 1 to 4 were produced in the same manner as in Example 1, except that the compressed rubber layer main body material was as shown in Table 1 above.

[0090] <Measurement of acetone extractables> As mentioned above, the acetone extractables were measured in accordance with JIS K6229:2015. In this measurement, a portion of the rubber layer (approximately 3 g) was sampled as a test piece from the compressed rubber layer of the friction transmission belt. Using acetone as the extraction solvent, the test piece was subjected to Soxhlet extraction for 8 hours. The acetone extractables were measured according to Method A. The results are shown in the "Acetone Extractables" column in Tables 2 and 3 below.

[0091] <Abrasion resistance evaluation> In accordance with JIS K6264-2, a Taber abrasion test was performed at room temperature under a load of 9.8 N, a rotation speed of 48 rpm, and a rotation time of 30 minutes to determine the amount of wear. Test specimens for the Taber abrasion test were prepared using rubber compositions shown in Table 1. The mass loss rate was calculated based on the amount of wear. The results are shown in Tables 2 and 3 below. The smaller the value, the better the abrasion resistance.

[0092] <Evaluation of water-injected power transmission capacity> Fig. 6 shows the pulley layout of a belt running test machine 70 for evaluating water-injected power transmission capacity. In Fig. 7, the symbol V indicates a V-ribbed belt.

[0093] This belt running tester 70 has a first drive pulley 71, a ribbed pulley with a pulley diameter of 121.6 mm, located at the lower left, and a second drive pulley 72, a ribbed pulley with a pulley diameter of 141.5 mm, located to the right of the first drive pulley 71. A first driven pulley 73, a ribbed pulley with a pulley diameter of 77.0 mm, is located diagonally above the right of the second drive pulley 72, and a second driven pulley 74, a ribbed pulley with a pulley diameter of 61.0 mm, is located above the second drive pulley 72. A first idler pulley 75, a flat pulley with a pulley diameter of 76.2 mm, is located between the first drive pulley 71 and the second driven pulley 74, and a second idler pulley 76, a flat pulley with a pulley diameter of 76.2 mm, is located between the first driven pulley 73 and the second driven pulley 74. The second driven pulley 74 is movable up and down and is configured to be able to bear an axial load.

[0094] Each of the V-ribbed belts fabricated in the examples and comparative examples was wound around first and second drive pulleys 71 and 72 and second and second driven pulleys 73 and 74 so that the V-rib sides were in contact, and around first and second idler pulleys 75 and 76 so that the tension rubber layer sides were in contact. An upward axial load (dead weight (DW)) of 706 N was applied to the second driven pulley 74 to apply belt tension. The winding angle of the V-ribbed belt around the second drive pulley 72 was 39°. Next, in an atmosphere at 21°C, the first drive pulley 71 and the second drive pulley 72 were rotated in the same direction at 800 rpm and 931 rpm, respectively, to forcibly slip the V-ribbed belt on the second drive pulley 72. Water droplets were also dripped at a rate of 300 ml per minute onto the V-rib surface at the beginning of the winding of the V-ribbed belt on the right side of the first drive pulley 71. The maximum value of the generated torque (maximum torque) was then measured using a torque meter attached to the second drive pulley 72. This measurement was performed before and after the durability test described below. The absolute value of the difference between the maximum torque before and after the durability test was calculated to confirm the change in maximum torque. The results are shown in Tables 2 and 3 below. The smaller the change in maximum torque, the more stably the water-injected transmission capacity is maintained and the more excellent the friction and wear resistance characteristics are.

[0095] <Durability test> FIG. 7 shows the layout of pulleys in a belt running test machine 80 for durability testing. This belt running tester 80 comprises a pair of drive ribbed pulley 81 and driven ribbed pulley 82, each having a pulley diameter of 60 mm, arranged on the left and right.

[0096] For each of the V-ribbed belts produced in the examples and comparative examples, the V-ribbed belt was wound around a drive ribbed pulley 81 and a driven ribbed pulley 82 so that the V-rib sides were in contact, and the drive ribbed pulley 81 was pulled sideways so that a dead weight (DW) of 1177 N was applied, while a rotational load of 3.8 kW was applied to the driven ribbed pulley 82. A belt running test was carried out in which the drive ribbed pulley 81 was rotated at a rotation speed of 3500 rpm for 96 hours in a room temperature environment (23±5°C).

[0097] [Table 2]

[0098] [Table 3]

[0099] As shown in Tables 2 and 3, it is clear that the friction transmission belt according to the embodiment of the present invention can achieve improved friction and wear resistance. [Explanation of symbols]

[0100] 2. Friction transmission belt (ribbed belt) 4 Belt body 6. Ribs 10 Compressed rubber layer 12 Compressed rubber layer body (rubber layer body) 14 Fiber member layer 14a Contact surface 20 Adhesive rubber layer 22 Adhesive rubber layer body (rubber layer body) 24 core wires 30 Back reinforcement fabric 40 Crosslinking device 46 Mold 46a Rib forming groove 60 Fiber materials 64 Rubber parts 70, 80 running test machine B. Friction transmission belt (V-ribbed belt) S Gap

Claims

1. A friction transmission belt having a compressed rubber layer that forms a contact portion with a pulley, the compression rubber layer includes a rubber layer main body made of a cross-linked product of a rubber composition, the acetone extractable content of the rubber layer main body, as determined by acetone extraction in accordance with JIS K6229:2015, is 5.0% by mass or less; Friction transmission belt.

2. the compression rubber layer further includes a fiber member layer laminated on the rubber layer main body, the fibrous material layer includes a fibrous material made of fabric, The fiber member contacts the pulley. The friction power transmission belt according to claim 1.

3. the fibrous member layer further includes a rubber member present in gaps between the fibrous members, The rubber member is made of a crosslinked product of the rubber composition that has permeated into the gap. The friction power transmission belt according to claim 2.

4. The rubber member contacts the pulley. The friction power transmission belt according to claim 3.

5. The rubber composition contains a raw rubber component, The main component of the raw rubber component is an ethylene-α-olefin elastomer. The friction power transmission belt according to any one of claims 1 to 4.

6. It is a V-ribbed belt. The friction power transmission belt according to any one of claims 1 to 5.

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