Butyylikumi

Butyylikumi, also known as butyl rubber, is a synthetic rubber with the chemical formula (CH2-C(CH3)2)n. It is a copolymer of isobutylene and a small amount of isoprene. This specific combination of monomers gives butyl rubber its unique properties, most notably its exceptional impermeability to gases and its resistance to heat and weathering. The low proportion of isoprene units in the polymer chain is crucial for its low gas permeability, as isoprene introduces double bonds that are more susceptible to diffusion.

The production of butyl rubber involves low-temperature polymerization, typically using a Ziegler-Natta catalyst or a Lewis acid catalyst such as aluminum chloride. This process is carried out in a solvent, often at temperatures below -100 degrees Celsius. After polymerization, the unreacted monomer is removed, and the rubber is recovered.

Butyl rubber is widely used in applications where gas retention is important. Its most common application is in the inner tubes of tires, where it significantly reduces air loss compared to natural rubber. It is also used in tire inner liners, the inner lining of tubeless tires that prevents air from escaping. Other uses include vibration damping mounts, protective clothing, sealants, and as a component in adhesives and coatings due to its excellent resistance to chemicals, ozone, and UV radiation. Its resilience and impermeability make it a valuable material in various industrial and automotive sectors.