BK-1675

Butyl rubber, sometimes just called \\\"butyl\\\", is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for isobutylene isoprene rubber. Butyl rubber is produced by polymerization of about 98% of isobutylene with about 2% of isoprene. Polyisobutylene is a colorless to light yellow viscoelastic material. It is generally odorless and tasteless, though it may exhibit a slight characteristic odor.