Trade Name
  • Butyl — Exxon Chemical, Lanxess
ASTM D1418 Designation
ASTM D2000/SAE J200 Type, Class
Apple Compound Designation
Standard Color
An all-petroleum product, Butyl is a copolymer of isobutylene and isoprene. Butyl is also known as Polyisobutylene or Polyisobutene.
Key Uses
Applications requiring an airtight seal; used for chemical weapons, agricultural chemicals, tire inner tubes, etc.
Temperature Range
Standard Compound: -50°F to +250°F
Hardness (Shore A)
40 to 80
With outstanding low permeability to gases, Butyl is especially effective in airtight sealing applications. It also features good to excellent resistance to ozone and sunlight aging.
Butyl further features excellent shock dampening capabilities. Only slightly affected by oxygenated solvents and other polar liquids, Butyl is often utilized in seals for hydraulic systems using synthetic fluids. It is good with MEK, and silicone fluids and greases.

Because it is a petroleum product, Butyl has poor resistance to hydrocarbon solvents and oils, and diester-based lubricants. Halogenated butyl has been introduced to expand oil and chemical resistance to this polymer. Chlorobutyl and Bromobutyl have better resistance. These polymers have been accepted by the medical industry for stoppers and septums for pharmaceutical applications.