Friction transmission belt

Abstract

The power transmission surface of a friction transmission belt (B) is formed of a crosslinked rubber composition obtained by crosslinking an uncrosslinked rubber composition containing a rubber component, pulp fibers, and meta-aramid staple fibers. The ratio (mass) of the pulp fiber content of the uncrosslinked rubber composition to the meta-aramid staple fiber content thereof is 0.15 or greater.

Description

Friction transmission belt

[0001] The present invention relates to a friction transmission belt.

[0002] A friction transmission belt having a power transmission surface formed of a crosslinked rubber composition containing pulp fibers and para-aramid short fibers is known (for example, Patent Documents 1 and 2).

[0003] Japanese Patent No. 6918047 Japanese Patent No. 6529327

[0004] The present invention is a friction transmission belt having a power transmission surface formed of a crosslinked rubber composition obtained by crosslinking an uncrosslinked rubber composition containing a rubber component, pulp fibers, and meta-aramid short fibers, wherein the mass ratio of the content of the pulp fibers to the content of the meta-aramid short fibers in the uncrosslinked rubber composition is 0.15 or more.

[0005] Perspective view of one piece of the cogged V-belt according to the embodiment. Cross-sectional view along the belt width direction of the cogged V-belt according to the embodiment. Cross-sectional view along the belt length direction of the cogged V-belt according to the embodiment. [[ID=IO]]

[0006] Hereinafter, embodiments will be described in detail.

[0007] FIGS. 1 to 3 show a cogged V-belt B according to an embodiment. This cogged V-belt B is an endless rubber friction transmission belt used, for example, in a transmission of a two-wheeled vehicle such as a scooter. The belt length of the cogged V-belt B is, for example, 200 mm or more and 5000 mm or less. The maximum belt width of the cogged V-belt B is, for example, 10 mm or more and 30 mm or less. The maximum belt thickness of the cogged V-belt B is, for example, 7.0 mm or more and 14.0 mm or less.

[0008] The cogged V-belt B according to the embodiment includes a V-belt main body 10, a core wire 20, an inner reinforcing cloth 30, and an outer reinforcing cloth 40.

[0009] The V-belt body 10 has a cross-sectional shape that is an isosceles trapezoid along the belt width direction. The angle between the two sides of the V-belt body 10 is, for example, 24° to 42°. The V-belt body 10 has a compression rubber layer 11 provided on the inner circumference side of the belt, an adhesive rubber layer 12 provided in the middle section, and a stretch rubber layer 13 provided on the outer circumference side of the belt. Lower cog forming portions 11a, which have a cross-sectional shape that is a sine curve along the belt length direction, are arranged at a constant pitch on the inner circumference of the compression rubber layer 11.

[0010] The compressed rubber layer 11 is formed of a crosslinked rubber composition X, which is formed by heating and pressurizing an uncrosslinked rubber composition X', which is kneaded with various rubber compounding agents containing pulp fibers and meta-aramid short fibers in addition to the rubber component, and then crosslinking it with a crosslinking agent. From the viewpoint of obtaining high power transmission efficiency, it is preferable that the crosslinked rubber composition X is arranged so that its direction of arrangement is in the direction of the belt width. In the cogged V belt B according to this embodiment, both sides of this compressed rubber layer 11 form a power transmission surface made of the crosslinked rubber composition X that contacts the pulley and transmits power.

[0011] Examples of rubber components in the uncrosslinked rubber composition X' and the crosslinked rubber composition X include chloroprene rubber (CR), ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber (CSM), and hydrogenated acrylonitrile rubber (H-NBR). Examples of CR include sulfur-modified CR, mercaptan-modified CR, and xanthogene-modified CR. Examples of ethylene-α-olefin elastomers include ethylene propylene dienterpolymer (EPDM), ethylene propylene copolymer (EPM), ethylene butene dienterpolymer (EBDM), ethylene butene copolymer (EBM), and ethylene octene copolymer (EOM). The rubber components preferably contain one or more of these, and from the viewpoint of obtaining high power transmission efficiency, it is more preferable to contain CR as the main component, and even more preferable to contain sulfur-modified CR as the main component. In this case, the content of the main component CR in the rubber component is greater than 50% by mass, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass, from the same viewpoint as above.

[0012] Furthermore, if the rubber component contains ethylene-α-olefin elastomer, the ethylene content is preferably 40% to 70% by mass, more preferably 50% to 60% by mass, and even more preferably 51% to 53% by mass, from the viewpoint of obtaining high power transmission efficiency. If the rubber component contains EPDM and / or EBDM, examples of the diene component include 5-ethylidene-2-norbornene (ENB), 5-vinyl-2-norbornene (VNB), dicyclopentadiene, 1,4-hexadiene, etc. Of these, 5-ethylidene-2-norbornene (ENB) is preferred as the diene component from the viewpoint of obtaining high power transmission efficiency. In that case, the ENB (diene) content is preferably 4% to 12% by mass, more preferably 5% to 10% by mass, and even more preferably 7% to 9% by mass, from the same viewpoint as above.

[0013] Pulp fibers are dispersed in the rubber component and oriented in the grain direction. Examples of pulp fibers include kraft pulp, non-wood pulp, and recycled paper pulp. Examples of kraft pulp include chemical pulp and mechanical pulp. Examples of chemical pulp include bleached hardwood kraft pulp (LBKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), unbleached softwood kraft pulp (NUKP), semi-bleached hardwood kraft pulp (LSBKP), semi-bleached softwood kraft pulp (NSBKP), hardwood sulfite pulp, and softwood sulfite pulp. Examples of mechanical pulp include stone ground pulp (SGP), pressurized stone ground pulp (TGP), chemigland pulp (CGP), crushed wood pulp (GP), and thermomechanical pulp (TMP). Examples of non-wood pulps include kenaf pulp, abaca pulp, cotton linter pulp, straw pulp, and bamboo pulp. Examples of recycled paper pulp include disintegrated recycled paper pulp, disintegrated and deinked recycled paper pulp (DIP), and disintegrated, deinked and bleached recycled paper pulp. The pulp fibers preferably contain one or more of these types, and more preferably contain kraft pulp from the viewpoint of obtaining high power transmission efficiency.

[0014] From the viewpoint of obtaining high power transmission efficiency, the average fiber diameter D1 of the pulp fibers is preferably 10 μm to 50 μm, more preferably 20 μm to 45 μm, and even more preferably 30 μm to 40 μm. From the same viewpoint as above, the average fiber length L1 of the pulp fibers is preferably 20 μm to 1000 μm, more preferably 40 μm to 800 μm, and even more preferably 400 μm to 600 μm. From the same viewpoint as above, the ratio of the average fiber length L1 of the pulp fibers to the average fiber diameter D1 (L1 / D1) is preferably 1 to 50, more preferably 10 to 20, and even more preferably 12 to 16.

[0015] The pulp fiber content A in the uncrosslinked rubber composition X' is preferably 3 to 25 parts by mass, more preferably 7 to 20 parts by mass, and even more preferably 12 to 18 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of obtaining high power transmission efficiency.

[0016] Meta-aramid staple fibers are dispersed in the rubber component and oriented in the direction of the grain. Examples of meta-aramid staple fibers include polymetaphenylene isophthalamide staple fibers. Commercially available meta-aramid staple fibers include Conex manufactured by Teijin and Nomex manufactured by DuPont.

[0017] From the viewpoint of obtaining high power transmission efficiency, the fiber diameter D2 of the meta-aramid short fibers is preferably 10 μm to 20 μm, more preferably 13 μm to 15 μm. From the same viewpoint as above, the fiber diameter D2 of the meta-aramid short fibers is preferably smaller than the average fiber diameter D1 of the pulp fibers. From the same viewpoint as above, the ratio of the average fiber diameter D1 of the pulp fibers to the fiber diameter D2 of the meta-aramid short fibers (D1 / D2) is preferably 1.1 to 3.5, more preferably 2 to 3. From the same viewpoint as above, the fineness of the meta-aramid short fiber filaments is preferably 1.5 dtex to 3 dtex, more preferably 2 dtex to 2.5 dtex.

[0018] From the viewpoint of obtaining high power transmission efficiency, the fiber length L2 of the meta-aramid short fiber is preferably 0.5 mm to 5 mm, more preferably 2 mm to 4 mm. From the same viewpoint as above, the ratio of the fiber length L2 of the meta-aramid short fiber to the fiber diameter D2 (L2 / D2) is preferably 80 to 400, more preferably 200 to 250. From the same viewpoint as above, it is preferable that the fiber length L2 of the meta-aramid short fiber is longer than the average fiber length L1 of the pulp fiber. From the same viewpoint as above, the ratio of the average fiber length L1 of the pulp fiber to the fiber length L2 of the meta-aramid short fiber (L1 / L2) is preferably 0.01 to 0.25, more preferably 0.1 to 0.2.

[0019] The content B of meta-aramid short fibers in the uncrosslinked rubber composition X' is preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass, and even more preferably 7 to 12 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of obtaining high power transmission efficiency.

[0020] The pulp fiber content A in the uncrosslinked rubber composition X' may be less than, the same as, or more than the meta-aramid staple fiber content B, but from the viewpoint of obtaining high power transmission efficiency, it is preferable that the pulp fiber content A is greater than the meta-aramid staple fiber content B. The mass ratio (A / B) of the pulp fiber content A to the meta-aramid staple fiber content B in the uncrosslinked rubber composition X' is 0.15 or more, preferably 0.2 to 3, more preferably 1 to 2.5, and even more preferably 1.2 to 2, from the viewpoint of obtaining high power transmission efficiency. The total content (A+B) of pulp fibers and meta-aramid staple fibers in the uncrosslinked rubber composition X' is preferably 10 to 35 parts by mass, more preferably 15 to 30 parts by mass, and even more preferably 20 to 25 parts by mass per 100 parts by mass of rubber component, from the same viewpoint as above.

[0021] Other rubber compounding agents include, for example, carbon black, crosslinking agents, softening agents, vulcanization accelerators, processing aids, co-crosslinking agents, and antioxidants. The uncrosslinked rubber composition X' may further contain meta-aramid short fibers.

[0022] Examples of carbon black include furnace blacks such as ISAF, HAF, MAF, FEF, SRF, GPF, and ECF. The carbon black preferably contains one or more of these, and from the viewpoint of obtaining high power transmission efficiency, it is preferable to include FEF. The carbon black content in the uncrosslinked rubber composition X' is preferably 20 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the rubber component, more preferably 40 parts by mass or more and 60 parts by mass or less if the rubber component contains CR, and more preferably 30 parts by mass or more and 50 parts by mass or less if the rubber component contains ethylene-α-olefin elastomer.

[0023] When the rubber component contains CR, the crosslinking agent is preferably a metal oxide such as zinc oxide or magnesium oxide, from the viewpoint of obtaining high power transmission efficiency. The content of the metal oxide crosslinking agent in the uncrosslinked rubber composition X' is, for example, 10 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the rubber component. When the rubber component contains ethylene-α-olefin elastomer, the crosslinking agent is preferably an organic peroxide, from the same viewpoint as above. The content of the organic peroxide crosslinking agent in the uncrosslinked rubber composition X' is, for example, 3 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component.

[0024] The storage modulus E' of the crosslinked rubber composition X at 25°C in the grain direction is preferably 150 MPa to 300 MPa, more preferably 200 MPa or more, and even more preferably 220 MPa or more, from the viewpoint of obtaining high power transmission efficiency. This storage modulus E' is measured according to JIS K6394:2007 under measurement conditions of 25°C temperature, static strain of 1.5%, dynamic strain of 0.1%, and frequency of 10 Hz.

[0025] The adhesive rubber layer 12 and the stretchable rubber layer 13 are also formed from a crosslinked rubber composition, which is obtained by heating and pressurizing an uncrosslinked rubber composition, in which various rubber compounding agents are mixed with the rubber component and kneaded, and then crosslinking it with a crosslinking agent. The adhesive rubber layer 12 and the stretchable rubber layer 13 may be formed from the same crosslinked rubber composition X as the compression rubber layer 11, or from different crosslinked rubber compositions.

[0026] The core wire 20 is embedded in the middle of the thickness direction of the adhesive rubber layer 12 of the V-belt body 10 so as to form a spiral with a pitch in the belt width direction. The core wire 20 is made of, for example, twisted yarn. Examples of fiber materials that form the core wire 20 include polyester fibers and aramid fibers. It is preferable that the core wire 20 is subjected to one or more of the following adhesive treatments before molding: an adhesive treatment in which it is immersed in a primer containing an epoxy compound or isocyanate compound and then heated; an adhesive treatment in which it is immersed in an RFL aqueous solution and then heated; and an adhesive treatment in which it is immersed in rubber glue and then dried.

[0027] The inner reinforcing fabric 30 is provided to cover the inner circumferential surface of the compression rubber layer 11 of the V-belt body 10. The inner reinforcing fabric 30 is made of, for example, woven fabric, knitted fabric, nonwoven fabric, etc. Examples of fiber materials that form the inner reinforcing fabric 30 include nylon fibers, polyester fibers, cotton, aramid fibers, etc. To provide adhesion to the compression rubber layer 11, it is preferable that the inner reinforcing fabric 30 is subjected to one or more of the following adhesive treatments before molding: an adhesive treatment in which it is immersed in a primer containing an epoxy compound or isocyanate compound and then heated; an adhesive treatment in which it is immersed in an RFL aqueous solution and then heated; an adhesive treatment in which it is immersed in rubber glue and then dried; and an adhesive treatment in which high viscosity rubber glue is coated on the surface facing the V-belt body 10 and then dried. In the cogged V-belt B according to this embodiment, the lower cog 14 is formed by covering the lower cog forming portion 11a of the compression rubber layer 11 with this inner reinforcing fabric 30.

[0028] The outer reinforcing fabric 40 is provided so as to cover the outer circumferential surface of the stretchable rubber layer 13 of the V-belt body 10. The outer reinforcing fabric 40 is made of, for example, woven fabric, knitted fabric, nonwoven fabric, etc. Examples of fiber materials that form the outer reinforcing fabric 40 include nylon fibers, polyester fibers, cotton, aramid fibers, etc. In order to impart adhesion to the stretchable rubber layer 13, it is preferable that the outer reinforcing fabric 40 is subjected to one or more of the following adhesive treatments before molding: an adhesive treatment in which the fabric is immersed in a primer containing an epoxy compound or isocyanate compound and then heated; an adhesive treatment in which the fabric is immersed in an RFL aqueous solution and then heated; an adhesive treatment in which the fabric is immersed in rubber glue and then dried; and an adhesive treatment in which the surface facing the V-belt body 10 is coated with high-viscosity rubber glue and then dried.

[0029] According to the cogged V-belt B of the embodiment described above, high power transmission efficiency can be obtained by having a mass ratio (A / B) of the pulp fiber content A to the meta-aramid short fiber content B in the uncrosslinked rubber composition X' before crosslinking of the crosslinked rubber composition X that forms the power transmission surface of the compression rubber layer 11, which is 0.15 or more.

[0030] The cogged V-belt B according to this embodiment can be manufactured by known methods.

[0031] In the above embodiment, the cogged V-belt B is provided with both an inner reinforcing fabric 30 and an outer reinforcing fabric 40, but it is not limited to this, and it may be provided with only one of the inner reinforcing fabric 30 or the outer reinforcing fabric 40.

[0032] In the above embodiment, a cogged V-belt B having only a lower cog 14 was used, but it is not limited to this, and it may also be a double cogged V-belt having an upper cog, or a raw edge V-belt without cogs, or even other types of friction transmission belts such as a flat belt or a V-ribbed belt.

[0033] (Cogged V-belts) Cogged V-belts were prepared according to the following Examples 1 to 4 and Comparative Examples 1 to 2. These cogged V-belts have the same configuration as the above embodiments, except that they do not have an inner reinforcing fabric. Table 1 shows the formulations of the uncrosslinked rubber compositions used to form each compression rubber layer.

[0034] <Example 1> An uncrosslinked rubber composition sheet was prepared by using sulfur-modified CR (manufactured by Tosoh Corporation) as the rubber component, and blending 50 parts by mass of FEF (manufactured by Tokai Carbon Co., Ltd.), 5 parts by mass of DOS (manufactured by Taoka Chemical Co., Ltd.), 5 parts by mass of zinc oxide (manufactured by Sakai Chemical Co., Ltd.), 5 parts by mass of magnesium oxide (manufactured by Kyowa Chemical Industry Co., Ltd.), 1 part by mass of stearic acid (manufactured by Kao Corporation), 8.1 parts by mass of pulp fibers (ARBOCEL PWC500 JRS Co., Ltd., average fiber diameter D1: 35 μm, average fiber length L1: 500 μm, L1 / D1: 14.3), and 8 parts by mass of meta-aramid short fibers (manufactured by Conex Teijin Co., Ltd., fiber diameter D2: 14 μm, fiber length L2: 3 mm, L2 / D2: 214). A cogged V-belt was prepared by forming a compressed rubber layer with a crosslinked rubber composition by arranging the uncrosslinked rubber composition sheet so that the row direction was in the belt width direction, and this was designated as Example 1.

[0035] <Examples 2-4 and Comparative Examples 1-2> A cogged V-belt with the same configuration as Example 1 was prepared, except that the amounts of pulp fibers and meta-aramid short fibers were 13.2 parts by mass and 10 parts by mass, respectively, per 100 parts by mass of rubber component, and this was designated as Example 2.

[0036] A cogged V-belt with the same configuration as in Example 1 was prepared, except that the amounts of pulp fibers and meta-aramid short fibers were 17.6 parts by mass and 8 parts by mass, respectively, per 100 parts by mass of rubber component, and this was designated as Example 3.

[0037] A cogged V-belt with the same configuration as in Example 1 was prepared, except that the amounts of pulp fibers and meta-aramid short fibers were 10 parts by mass and 13.2 parts by mass, respectively, per 100 parts by mass of rubber component, and this was designated as Example 4.

[0038] A cogged V-belt identical in structure to that of Example 1 was prepared, except that pulp fibers were not included and the amount of meta-aramid short fibers was 16 parts by mass per 100 parts by mass of rubber component. This was designated as Comparative Example 1.

[0039] A cogged V-belt identical in structure to that of Example 1 was prepared, except that the amount of pulp fibers was 16.2 parts by mass per 100 parts by mass of rubber components, and meta-aramid short fibers were not included. This was designated as Comparative Example 2.

[0040]

[0041] (Test Evaluation) The following test evaluations were conducted. The results are shown in Table 2.

[0042] <Storage Modulus E'> For each of Examples 1 to 4 and Comparative Examples 1 to 2, the storage modulus E' of the crosslinked rubber composition forming the compression rubber layer at 25°C in the grain direction was measured in accordance with JIS K6394:2007. The measurement conditions were a temperature of 25°C, a static strain of 1.5%, a dynamic strain of 0.1%, and a frequency of 10 Hz.

[0043] <Dynamic Friction Coefficient> For each of Examples 1-4 and Comparative Examples 1-2, a 5 mm square test specimen of the crosslinked rubber composition forming the compression rubber layer was prepared. The test specimen was set in a pin-on-disk type friction and wear tester. At this time, the surface of the test specimen perpendicular to the grain direction was used as the sliding surface, and this sliding surface was brought into contact with the surface of a disc-shaped mating material made of S45C so that the sliding direction was perpendicular to both the grain direction and the antigravity direction. A load of 19.6 N was applied to the test specimen from above, and the mating material was rotated at a rotational speed of 80 rpm in a room temperature atmosphere of 25°C. The steady value of the frictional force acting on the test specimen was measured, and the dynamic friction coefficient was calculated by dividing it by the load of 19.6 N (drag force). For Examples 1-4 and Comparative Example 2, the dynamic friction coefficient of Comparative Example 1 was set to 1 for relative evaluation.

[0044] <Transmission Efficiency>For each of Examples 1 to 4 and Comparative Examples 1 and 2, a dead weight of 785 N was loaded on the driving pulley and the driven pulley with winding diameters of 78 mm and 102 mm, respectively, in a direction away from the driven pulley laterally. The driving pulley was rotated at 5000 rpm with a driving shaft torque of 2 N·m to run the belt, and the transmission efficiency was calculated based on the following formula (1). Also, belt running was performed with driving shaft torques of 4 N·m and 6 N·m, respectively, to calculate the transmission efficiency. The average value of the three transmission efficiencies with the variable driving shaft torque was obtained. Then, for Examples 1 to 4 and Comparative Example 2, the transmission efficiency of Comparative Example 1 was set to 1 for relative evaluation.

[0045]

[0046]

[0047] The present invention is useful in the technical field of friction drive belts.

[0048] B Cogged V-belt (friction drive belt) 10 V-belt body 11 Compression rubber layer 11a Lower cog forming part 12 Adhesive rubber layer 13 Extension rubber layer 14 Lower cog 20 Core wire 30 Inner reinforcing cloth 40 Outer reinforcing cloth

Claims

1. A friction transmission belt having a power transmission surface formed of a crosslinked rubber composition obtained by crosslinking an uncrosslinked rubber composition containing rubber components, pulp fibers, and meta-aramid short fibers, wherein the mass ratio of the pulp fiber content in the uncrosslinked rubber composition to the meta-aramid short fiber content is 0.15 or more.

2. A friction transmission belt according to claim 1, wherein the rubber component mainly consists of chloroprene rubber.

3. A friction transmission belt according to claim 1 or 2, wherein the pulp fibers include kraft pulp.

4. A friction transmission belt according to any one of claims 1 to 3, wherein the average fiber diameter of the pulp fibers is 10 μm or more and 50 μm or less.

5. A friction transmission belt according to any one of claims 1 to 4, wherein the average fiber length of the pulp fibers is 20 μm or more and 1000 μm or less.

6. A friction transmission belt according to any one of claims 1 to 5, wherein the ratio of the average fiber length of the pulp fibers to the average fiber diameter is 1 or more and 50 or less.

7. A friction transmission belt according to any one of claims 1 to 6, wherein the fiber diameter of the meta-aramid short fibers is smaller than the average fiber diameter of the pulp fibers.

8. A friction transmission belt according to any one of claims 1 to 7, wherein the ratio of the average fiber diameter of the pulp fibers to the fiber diameter of the meta-aramid short fibers is 1.1 or more and 3.5 or less.

9. A friction transmission belt according to any one of claims 1 to 8, wherein the fiber length of the meta-aramid short fibers is longer than the average fiber length of the pulp fibers.

10. A friction transmission belt according to claim 9, wherein the ratio of the average fiber length of the pulp fibers to the fiber length of the meta-aramid short fibers is 0.01 or more and 0.25 or less.

11. A friction transmission belt according to any one of claims 1 to 10, wherein the content of the pulp fibers in the uncrosslinked rubber composition is 3 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the rubber component.

12. A friction transmission belt according to any one of claims 1 to 11, wherein the content of the meta-aramid short fibers in the uncrosslinked rubber composition is 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the rubber component.

13. A friction transmission belt according to any one of claims 1 to 12, wherein the content of the pulp fibers in the uncrosslinked rubber composition is greater than the content of the meta-aramid short fibers.

14. A friction transmission belt according to any one of claims 1 to 13, wherein the mass ratio of the pulp fiber content in the uncrosslinked rubber composition to the meta-aramid short fiber content is 2.5 or less.

15. A friction transmission belt according to any one of claims 1 to 14, wherein the total content of the pulp fibers and the meta-aramid short fibers in the uncrosslinked rubber composition is 10 parts by mass or more and 35 parts by mass or less per 100 parts by mass of the rubber component.

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