Rubber composition for transmission belt and transmission belt

Patent metadata

Field	Value
Publication number	US-12584009-B2
Application number	US-202318722137-A
Country	US
Kind code	B2
Filing date	Jan 19, 2023
Priority date	Jan 20, 2022
Publication date	Mar 24, 2026
Grant date	Mar 24, 2026

Abstract

A rubber composition for a power-transmission belt includes: a polymer component including an ethylene-α-olefin elastomer; carbon black; and clay, in which the ethylene-α-olefin elastomer has a Mooney viscosity at 125° C. of 25 ML (1+4) 125° C. or less, the clay has a pH of 5.5 or higher, a total amount of the carbon black and the clay is 80 parts by mass to 180 parts by mass with respect to 100 parts by mass of the polymer component, and a mass ratio of the carbon black to the clay is clay/carbon black=0.2/1 to 1.2/1.

First claim

The invention claimed is:

1 . A rubber composition for a power-transmission belt, the composition comprising:
a polymer component comprising an ethylene-α-olefin elastomer; carbon black; clay; and a short fiber, wherein the ethylene-α-olefin elastomer has a Mooney viscosity at 125° C. of 25 ML (1+4) 125° C. or less, the clay has a pH of 5.5 or higher, a total amount of the carbon black and the clay is 80 parts by mass to 180 parts by mass with respect to 100 parts by mass of the polymer component, a mass ratio of the carbon black to the clay is clay/carbon black=0.2/1 to 1.2/1, a proportion of the short fiber is 5 parts by mass to 100 parts by mass with respect to 100 parts by mass of the polymer component, a crosslinked product of the rubber composition has an 8% bending stress in a short fiber orthogonal direction of 6 MPa to 8 MPa, and the crosslinked product of the rubber composition has an 8% bending stress in a short fiber parallel direction of 2 MPa to 3 MPa.

2 . The rubber composition according to claim 1 , wherein the crosslinked product of the rubber composition has a rubber hardness Hs (type A) of 88 degrees to 96 degrees.

3 . The rubber composition according to claim 1 , wherein the short fiber is free from an aramid short fiber.

4 . The rubber composition according to claim 1 , wherein the clay comprises a calcined clay.

5 . The rubber composition according to claim 1 , wherein the carbon black comprises a hard carbon black.

6 . A power-transmission belt, comprising:
the crosslinked product of the rubber composition according to claim 1 .

7 . The power-transmission belt according to claim 6 , being a raw-edge cogged V-belt.

8 . The power-transmission belt according to claim 7 , being a variable speed belt.

Assignees

• Mitsuboshi Belting Ltd

Inventors

• Ozaki Toshiki

Classifications

• F16G5/20

  with a contact surface of special shape, e.g. toothed · CPC title

• F16G5/04

  made of rubber (F16G5/02 takes precedence {consisting of several parts F16G5/16}) · CPC title

• C08L2312/00

  Crosslinking · CPC title

• C08L2205/16

  Fibres; Fibrils · CPC title

• C08K2201/014

  Additives containing two or more different additives of the same subgroup in C08K · CPC title