Search

JP-2026075601-A - Rubber composition, reinforcing fabric, power transmission belt, and method for manufacturing a power transmission belt

JP2026075601AJP 2026075601 AJP2026075601 AJP 2026075601AJP-2026075601-A

Abstract

[Problem] To improve the wear resistance and productivity of power transmission belts. [Solution] A rubber composition containing an ethylene-long-chain α-olefin-non-conjugated polyene copolymer, in which the long-chain α-olefin units have 4 or more carbon atoms, in a proportion of 25% by mass or more in the rubber component is compounded with the fabric of the transmission belt. The rubber composition may further contain silica, hard carbon black, aliphatic oil, tackifier, etc. At least a portion of the belt surface may be covered with a composite of the crosslinked rubber composition and the fabric to produce the transmission belt. This transmission belt may be a wrapped V-belt. [Selection Diagram] None

Inventors

  • テセマ イヨブ アシェナフィ
  • 吉村 健太郎

Assignees

  • 三ツ星ベルト株式会社

Dates

Publication Date
20260508
Application Date
20251001
Priority Date
20241022

Claims (17)

  1. A rubber composition for compounding with fabric for a transmission belt, Contains rubber components, A rubber composition wherein the rubber component comprises an ethylene-long-chain α-olefin-non-conjugated polyene copolymer having 4 or more carbon atoms in the long-chain α-olefin unit, and the proportion of the ethylene-long-chain α-olefin-non-conjugated polyene copolymer is 25% by mass or more in the rubber component.
  2. Furthermore, the rubber composition according to claim 1, further comprising silica.
  3. The rubber composition according to claim 1 or 2, further comprising hard carbon black.
  4. Furthermore, the rubber composition according to any one of claims 1 to 3, further comprising an aliphatic oil.
  5. The rubber composition according to claim 4, wherein the proportion of the aliphatic oil is 10 to 40 parts by mass per 100 parts by mass of the rubber component.
  6. A rubber composition according to any one of claims 1 to 5, further comprising a tackifier.
  7. The rubber composition according to claim 6, wherein the proportion of the tackifier is 10 parts by mass or more per 100 parts by mass of the rubber component.
  8. The rubber component further comprises an ethylene-propylene-nonconjugated polyene copolymer. The rubber composition according to any one of claims 1 to 7, wherein the ethylene-long-chain α-olefin-non-conjugated polyene copolymer is an ethylene-butene-non-conjugated diene copolymer, and the proportion of the ethylene-long-chain α-olefin-non-conjugated polyene copolymer is 55 to 90% by mass of the rubber component.
  9. The rubber composition according to any one of claims 1 to 8, wherein the minimum viscosity Vm of Mooney scorch at 125°C in the uncrosslinked material is 30 or less.
  10. A rubber composition according to any one of claims 1 to 9, wherein the crosslinked material has a rubber hardness of 55 or higher.
  11. A reinforcing fabric for covering at least a portion of the surface of a power transmission belt, comprising a composite of the fabric and a crosslinked rubber composition according to any one of claims 1 to 10.
  12. A transmission belt comprising the reinforcing fabric described in claim 11, A transmission belt in which at least a portion of the surface of the transmission belt is covered with the reinforcing fabric.
  13. The transmission belt according to claim 12, which is a wrapped V-belt.
  14. A method for manufacturing a power transmission belt, comprising a compounding step of compounding a fabric with a rubber composition according to any one of claims 1 to 10 to obtain an uncrosslinked composite for forming a reinforcing fabric.
  15. The method for manufacturing a transmission belt according to claim 14, wherein the composite step is a friction treatment, coating treatment, lamination treatment, or soaking treatment.
  16. A method for manufacturing a transmission belt according to claim 14 or 15, further comprising a lap joint step of diagonally cutting the uncrosslinked composite and overlapping and joining the ends to obtain a reinforcing fabric precursor.
  17. The method for manufacturing a power transmission belt according to claim 16, further comprising a covering step of covering the belt body precursor with the reinforcing fabric precursor.

Description

This invention relates to a rubber composition used in power transmission belts, a reinforcing fabric, a power transmission belt containing this rubber composition, and a method for manufacturing the same. Power transmission belts are broadly classified into friction belts and meshing belts. Examples of friction belts include flat belts, V-belts, and V-ribbed belts, while examples of meshing belts include toothed belts. V-belts include raw-edge type (raw-edge V-belts), where the friction transmission surface (V-shaped side) is exposed rubber layer, and wrapped type (wrapped V-belts), where the friction transmission surface is covered by an outer fabric (cover fabric). These V-belts are used differently depending on the application, based on the surface properties of the friction transmission surface (the coefficient of friction between the rubber layer and the cover fabric). Many of these power transmission belts have at least a portion of their surface covered with reinforcing fabric to increase their strength and abrasion resistance. The reinforcing fabric is formed as a composite of fabric and rubber composition by impregnating woven, knitted, or nonwoven fabrics with rubber adhesive, or by rubbing or laminating a rubber composition into them. This composite of fabric and rubber composition improves strength and abrasion resistance, and also imparts tackiness (adhesion), thereby improving the processability during belt molding. For example, the manufacturing process for a wrapped V-belt includes a friction process in which a rubber composition is rubbed into the canvas, a lap joint process in which the reinforcing fabric is cut diagonally and then the ends are overlapped and joined, and a covering process in which the belt body is covered with the reinforcing fabric. Therefore, the reinforcing fabric used in wrapped V-belts requires not only strength and abrasion resistance, but also properties that allow for good processability in each of the above processes. For example, Japanese Patent Publication No. 2024-58593 (Patent Document 1) discloses a friction transmission belt formed from a reinforcing fabric containing a rubber composition in which the minimum viscosity of Mooney scorch at 125°C in the uncrosslinked portion is 21 or less, and the rubber hardness in the crosslinked portion is 55 or more, for the purpose of improving friction workability and wear resistance. Furthermore, International Publication No. 2015/194116 (Patent Document 2) discloses a wrapped V-belt made of a rubber composition containing an ethylene-α-olefin elastomer with an ethylene content of 40% by mass or more and 56% by mass or less as a rubber component (polymer component), with the aim of realizing a transmission belt with excellent wear resistance and processability. Japanese Patent Publication No. 2024-58593International Publication No. 2015/194116 Figure 1 is a schematic partial cross-sectional perspective view of a cut wrapped V-belt.Figure 2 is a graph showing the behavior of Mooney viscosity to illustrate the method for measuring the minimum Mooney scorch viscosity (Vm) and scorch time.Figure 3 shows the layout of the wear resistance test for the wrapped V-belt obtained in the example. [Rubber composition] (Rubber component (A)) The rubber composition of the present invention is a rubber composition for compounding with fabric for a power transmission belt, and contains rubber component (A). Rubber component (A) is characterized by containing an ethylene-long-chain α-olefin-non-conjugated polyene copolymer (A1) in which the long-chain α-olefin unit has 4 or more carbon atoms. (Ethylene-long-chain α-olefin-non-conjugated polyene copolymer (A1)) The ethylene-long-chain α-olefin-non-conjugated polyene copolymer (A1) comprises ethylene units, long-chain α-olefin units, and non-conjugated polyene units as constituent units, wherein the long-chain α-olefin units have four or more carbon atoms. The number of carbon atoms in the long-chain α-olefin unit should be four or more, but for example, 4 to 20, preferably 4 to 10, more preferably 4 to 8, more preferably 4 to 6, and most preferably 4 to 5. If the number of carbon atoms is too high, the wear resistance of the transmission belt may decrease. Examples of α-olefins for forming long-chain α-olefin units having four or more carbon atoms include linear α-C4-20 olefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-nonadecene, and 1-eicosene; and branched α- C4-20 olefins such as 4-methyl-1-pentene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1 - tetradecene. These α-olefins can be used individually or in combination of two or more. Of these α-olefins, α- C4-10 olefins such as 1-butene, 1-hexene, and 1-octene are preferred. Linear α- C4-8 olefins are even more preferred, linear α- C4-6 olefins are even more preferred, and linear α- C4-5 olefins are most preferred, from the viewpoint of improving the productivity of power transmission