CN-116601408-B - High-performance toothed belt made of EPDM

Abstract

The invention relates to an elastomeric toothed belt comprising a fabric spanning the teeth of the toothed belt, wherein the elastomeric mixture forming the teeth contains at least 70% by weight of crosslinked ethylene-propylene rubber (EPM) and/or crosslinked ethylene-propylene terpolymer rubber (EPDM) based on the polymer proportion of the elastomeric mixture, and wherein an intermediate layer is arranged between the fabric and the elastomeric mixture forming the teeth, the intermediate layer comprising at least 70% by weight of hydrogenated acrylonitrile-butadiene rubber (HNBR) based on the polymer proportion of the intermediate layer. Such elastomeric toothed belts are halogen-free and are characterized by improved durability and good low temperature stability characteristics. The invention further relates to a method for producing these elastomeric toothed belts and to the use of a hydrogenated acrylonitrile-butadiene rubber (HNBR) layer in these toothed belts to increase the service life, improve the low temperature stability and improve the adhesion between teeth and fabric.

Inventors

• Reinhard Tevez
• SATTLER HEIKO
• Jane Mikhalka
• Antonius Dickmans
• KANZOW HENNING
• Stephanie Coats

Assignees

• 康蒂泰克驱动系统有限公司

Dates

Publication Date

20260508

Application Date

20211125

Priority Date

20201218

Claims (20)

1. 1. Elastomeric toothed belt having a main body with a length, sides arranged at a lateral distance from each other and an inner side and an outer side, and a plurality of teeth arranged spaced apart from each other in a longitudinal direction on the inner side or the outer side of the main body and a fabric spanning the teeth, characterized in that the elastomer mixture forming the teeth contains at least 70% by weight of crosslinked ethylene-propylene rubber (EPM) and/or crosslinked ethylene-propylene terpolymer rubber (EPDM) based on the polymer proportion of the elastomer mixture, and in that an intermediate layer is arranged between the fabric and the elastomer mixture forming the teeth, the intermediate layer containing at least 70% by weight of hydrogenated acrylonitrile-butadiene rubber (HNBR) based on the polymer proportion of the intermediate layer.
2. 2. The elastomeric toothed belt of claim 1, wherein the teeth contain the crosslinked ethylene-propylene rubber (EPM) and/or ethylene-propylene terpolymer rubber (EPDM) in a proportion of at least 80% by weight, based on the polymer proportion of the elastomeric mixture forming the teeth.
3. 3. The elastomeric toothed belt of claim 2, wherein the teeth contain at least 90% by weight of the crosslinked ethylene-propylene rubber (EPM) and/or ethylene-propylene terpolymer rubber (EPDM) based on the polymer proportion of the elastomeric mixture forming the teeth.
4. 4. The elastomeric toothed belt of claim 3, wherein the teeth contain at least 95% by weight of the crosslinked ethylene-propylene rubber (EPM) and/or ethylene-propylene terpolymer rubber (EPDM) based on the polymer proportion of the elastomeric mixture forming the teeth.
5. 5. The elastomeric toothed belt of claim 1, wherein the body is formed from crosslinked ethylene-propylene rubber (EPM) and/or ethylene-propylene terpolymer rubber (EPDM) as elastomers.
6. 6. The elastomeric toothed belt of claim 1, wherein the crosslinked elastomer in the elastomer mixture forming the teeth is a sulfur-crosslinked or peroxidically crosslinked elastomer.
7. 7. The elastomeric toothed belt of claim 6, wherein the crosslinked elastomer in the elastomer mixture forming the teeth is a peroxidically crosslinked elastomer.
8. 8. The elastomeric toothed belt of claim 1, wherein the intermediate layer contains at least 80% by weight of hydrogenated acrylonitrile-butadiene rubber (HNBR) based on the polymer proportion of the intermediate layer.
9. 9. The elastomeric toothed belt of claim 8, wherein the intermediate layer contains at least 90% by weight of hydrogenated acrylonitrile-butadiene rubber (HNBR) based on the polymer proportion of the intermediate layer.
10. 10. The elastomeric toothed belt of claim 1, wherein the hydrogenated acrylonitrile-butadiene rubber has a hydrogenation degree in the range from 70% to 99% and/or an acrylonitrile content of 18% to 47% by mass.
11. 11. The elastomeric toothed belt of claim 10, wherein the hydrogenated acrylonitrile-butadiene rubber has a degree of hydrogenation in the range from 95% to 98%.
12. 12. The elastomeric toothed belt of claim 10, wherein the hydrogenated acrylonitrile-butadiene rubber has an acrylonitrile content of 30% to 37% by mass.
13. 13. The elastomeric toothed belt of claim 1, wherein the intermediate layer has a thickness of at least 10 μιη and/or a shore a hardness of less than 90.
14. 14. The elastomeric toothed belt of claim 13, wherein the intermediate layer has a thickness in the range from 10 μιη to 500 μιη.
15. 15. The elastomeric toothed belt of claim 13, wherein the intermediate layer has a thickness in the range from 50 μιη to 200 μιη.
16. 16. The elastomeric toothed belt of claim 1, wherein the intermediate layer contains an additive for imparting conductivity.
17. 17. The elastomeric toothed belt of claim 16, wherein said additive is in the form of carbon black.
18. 18. The elastomeric toothed belt of claim 16 or 17, wherein the intermediate layer contains the additive in a proportion of 20 to 70 parts based on 100 parts of polymer in the intermediate layer, and/or wherein the elastomeric toothed belt has a resistance of less than 50M Ω as determined according to ISO 9563:2015.
19. 19. The elastomeric toothed belt of claim 18, wherein the intermediate layer contains the additive in a proportion of 30 to 60 parts based on 100 parts of polymer in the intermediate layer.
20. 20. The elastomeric toothed belt of claim 18, wherein the elastomeric toothed belt has a resistance of less than 5M Ω as determined according to ISO 9563:2015.

Description

High-performance toothed belt made of EPDM Technical Field The invention relates to an elastomeric toothed belt comprising a fabric spanning the teeth of the toothed belt, wherein the elastomeric mixture forming the teeth contains at least 70% by weight of crosslinked ethylene-propylene rubber (EPM) and/or crosslinked ethylene-propylene terpolymer rubber (EPDM) based on the polymer proportion of the elastomeric mixture, and wherein an intermediate layer is arranged between the fabric and the elastomeric mixture forming the teeth, the intermediate layer comprising at least 70% by weight of hydrogenated acrylonitrile-butadiene rubber (HNBR) based on the polymer proportion of the intermediate layer. The invention further relates to a method for producing these elastomeric toothed belts and to the use of a hydrogenated acrylonitrile-butadiene rubber (HNBR) layer in these toothed belts to increase the service life, improve the low temperature stability and improve the adhesion between teeth and fabric. Background Toothed belts are conventionally made of elastomer mixtures based on chloroprene (CH 2＝C(Cl)-CH＝CH2). Higher quality toothed belts containing sulfur crosslinked HNBR (=hydrogenated acrylonitrile/butadiene rubber) as base polymer can be used as a substitute. Furthermore, HNBR using peroxidically crosslinking is known to have particularly good thermal aging resistance. The strength of HNBR elastomers can be further improved by adding zinc salts of acids having free-radically polymerizable groups, such as, in particular, acrylic acid or methacrylic acid, but also sorbic acid, for peroxidic crosslinking. For reinforcement, conventional toothed belts comprise a fabric layer on the toothed side and generally also on the side opposite the toothed side, which covers the teeth or belt body of the belt and by means of which the toothed pulley is engaged between the teeth of the belt. In order to firmly attach such a fabric to the teeth of a toothed belt, the fabric is typically first coated with a resorcinol/formaldehyde and latex mixture (also known as RFL layer). Subsequently applied as adhesion promoting mixture is an elastomer mixture, which is usually formed of the same elastomer as the teeth of the toothed belt, to ensure good connection of the coated fabric to the elastomer of the teeth. In the case of toothed belts with teeth formed of chloroprene, a chloroprene coating is applied to the fabric, whereas in the case of toothed belts with teeth formed of HNBR, an HNBR coating is applied to the fabric. The adhesion promoting mixture is conventionally applied by dissolving the uncrosslinked elastomer in a suitable organic solvent (e.g., toluene, xylene or carboxylate) and applying it to the RFL treated fabric in an amount such that an adhesion promoting layer having a thickness in the range of about 10 μm is formed upon removal of the solvent. Alternatively, a thin layer of elastomer may be applied to the RFL treated fabric by calendaring. However, a problem with conventional high performance toothed belts made of chloroprene rubber is their chlorine content, because for example the burning of scrapped chloroprene articles releases hydrogen chloride, which requires expensive and complex combustion exhaust gas filtration. Thus, there is a need for alternative materials for chloroprene rubbers which impart desirable comparable performance characteristics, but which are free of chlorine or other halogens. HNBR meets the requirement of as low a chlorine content as possible, but on the other hand has the disadvantage of relatively high price and relatively low flexibility in the lower temperature range. Elastomeric materials that better meet the requirements of comparable performance characteristics include ethylene-propylene elastomers such as, for example, ethylene-propylene-diene Elastomers (EPDM). For example, DE 10 2008 055 530 describes a toothed belt for a camshaft drive in an internal combustion engine, wherein the elastomer of the toothed belt body consists of an EPDM mixture which also contains special short fibers having a length in the range from 2mm to 5 mm. The mixtures described in DE 10 2008 055 530 are said to allow NBR and HNBR to be dispensed with at least to a large extent, while achieving improved low-temperature flexibility and longer service life and identical or better force transmission. However, in the case of toothed belts made of EPDM in which a layer of EPDM is disposed between the fabric of the toothed belt and the EPDM, it was found that sufficient adhesion of the fabric to the EPDM material could not be achieved, and therefore these toothed belts exhibited only insufficient durability. Even if the fabric having the conventional RFL coating is directly adhered to the teeth of the toothed belt made of EPDM, a sufficient service life of the toothed belt cannot be achieved. EP 1 677 030 B1 describes a toothed belt having a body made of EPDM and a fabric fixed thereto, wherein the fabric