Butyl rubber is an elastomeric polymer that is used in a wide variety of construction adhesives and sealants. Because of its unique properties it also is used in the automotive and food processing industries among others. Butyl adhesives can be applied in a number of different forms. It can be used as a hot melt, solvent solution, preformed tape or gasket, and as a gun-dispensable sealant. Butyl rubber can be used as a primary base resin or as an additive for tack and other desired properties.
RESULTING PROPERTIES
A typical butyl rubber caulking compound has the following composition shown in above. ASTM C1085 is a standard specification for a butyl rubber based solvent release sealant with a maximum of 10% joint movement capability. These have a service life of 5-15 years depending on the application. Butyl sealants are known for excellent adhesion to most substrates. However, they can stain adjacent surfaces and have relatively poor recovery from extension. The polymeric compositions along with the other additives will affect both the application and the ultimate performance properties of the joint. Typically solvent based butyl sealants have the following characteristics3
Excellent adhesion to many common substrates
Limited movement capabilities, generally up to +/- 10%
Excellent weathering
Good use as both adhesives and sealants
Sometimes used in curtain wall applications where adhesion to rubber compounds is needed
Most are stringy and difficult to apply neatly
May show some shrinkage after cure; may harden and crack over time on exposed surfaces.
