Full definition
Neoprene, or polychloroprene (CR), is a synthetic rubber widely used in the manufacturing of power transmission belts. Its unique properties make it an ideal choice for the structural medium of these belts, as it surrounds and bonds the tension cords while also providing an effective grip surface in pulley grooves. The material gained prominence from the 1950s to the 1990s, owing to its balanced resistance to various environmental factors, including mineral oils, moderate heat (up to 90°C continuous), ozone, and cyclic flexing fatigue, which is crucial for ensuring the longevity and reliability of power transmission systems. The hardness of neoprene typically ranges from 55 to 75 Shore A, making it adaptable for different applications that require specific flexibility and strength characteristics.
One of the defining features of neoprene is its excellent dynamic fatigue life, allowing it to endure millions of flex cycles without significant degradation. This makes neoprene belts suitable for high-performance applications where flexibility is essential. While neoprene exhibits moderate oil resistance, it is particularly adept at resisting incidental contact with lubricants and greases. Additionally, its flame retardancy properties enhance safety in various industrial environments. Neoprene also offers good adhesion to a variety of tension cords, including polyester, aramid, and fiberglass, ensuring robust construction and durability of the belts.
Since the 2000s, however, there has been a marked shift towards the use of EPDM (ethylene propylene diene monomer) in standard drive applications. EPDM belts generally provide a service life that is 20-40% longer and exhibit superior heat resistance in cleaner environments. Despite this trend, neoprene remains a critical material for specific applications, particularly in oily environments such as metalworking, food processing industries involving fats, and automotive engine bays exposed to oil mist. Belt manufacturers incorporating CR compounds include well-known brands such as Gates, Continental, Optibelt, and Mitsuboshi. The classification of belt materials, including neoprene, is outlined in ISO 1813, which provides guidelines for the assessment of rubber materials used in power transmission belts.