How to glue Halogenated Butyl Rubber (BIIR-Rubber) also called Brominated isobutylene-isoprene rubber

Halogenated butyl rubber is obtained by halogenating butyl rubber with either bromine or chlorine. Bromine or chlorine is added to the butyl polymer in a molar ratio of 1:1 halogen to isoprene.

The primary performance property of butyl rubber is its extremely low permeability to gas and moisture. This is attributed to the long aliphatic polymer backbone and the absence of large pendant groups, which allows the polymer chains to pack very tightly. The primary difference between halogenated butyl and regular butyl rubber is that the former can be crosslinked by various curing systems, while the latter cannot. This results in halogenated butyl rubber having improved thermal resistance compared to regular butyl rubber because it can be crosslinked with crosslinking systems without sulfur. Additionally, the use of non-sulfur-based curing systems also results in a cleaner rubber with fewer leachable substances. This makes halobutyl rubber compounds suitable for pharmaceutical closures. When formulated to provide good flex resistance, chlorobutyl-vulcanizates with natural rubber are widely used as inner liners for tubeless tires, especially in steel-belted radial tires.

BIIR (Brominated isobutylene-isoprene rubber) is widely used due to its excellent properties and durability. It is used for applications such as tire inner liners, sidewalls, tire treads, hoses, and engine mounts, where its low gas permeability and heat resistance are critical. BIIR also functions as electrical insulation in electronic applications due to its ability to resist moisture and gas permeability. Industrially, BIIR is used for various purposes such as conveyor belts, bladder curing, membranes, tank liners, steam hoses, pneumatic membranes, and gas bladders, where it delivers reliable performance in demanding environments. In medical applications, BIIR is used in pharmaceutical closures due to its purity and minimal leachables, ensuring product quality and safety. It is known for its reliability and effectiveness.

The surface tension for Halogenated Butyl Rubber (BIIR) typically ranges between 25 and 30 dyn/cm.

Halogenated butyl rubber (BIIR) is available under various trade names, each representing specific formulations developed by leading manufacturers. Some of these trade names include EXXON BROMOBUTYL, EXXON CHLOROBUTYL, POLYSAR BROMOBUTYL, and POLYSAR CHLOROBUTYL.

Bonding

Halogenated butyl rubber (BIIR) can be a challenging rubber type, and in several cases it is recommended (depending on the part requirements) to surface treat the items with primer or corona/plasma treatment prior to bonding. Additionally, thorough cleaning and degreasing with a non-aggressive cleaning fluid is important to remove any contaminants that may hinder good adhesion.

Choose an adhesive specifically formulated to bond with rubber and silicone.

• -Cyanoacrylate adhesives can be useful for fast bonding of BIIR in certain applications, especially where extreme durability or chemical resistance is not required. It is important to select a cyanoacrylate adhesive suitable for rubber and silicones, or a variant that specifically indicates compatibility with BIIR.
• -UV-curing adhesives work by curing quickly upon exposure to ultraviolet light. When it comes to BIIR, it is important to select a UV-curing adhesive compatible with rubber and silicones, as BIIR has specific chemical and surface properties that may affect adhesion. It is important to ensure that the UV light can reach the adhesive and initiate the curing process correctly, which can be challenging if the BIIR part is not transparent or does not allow UV light to penetrate to the adhesive.

After bonding, allow the BIIR adhesive to cure according to the manufacturer’s instructions. Then perform the necessary tests to ensure the bonding meets the required strength and performance properties for the specific application.

Manufacturers

This is a list of manufacturers of Halogenated Butyl Rubber (BIIR) and their associated trade names:

ExxonMobil Chemical:
EXXON BROMOBUTYL
EXXON CHLOROBUTYL

Bayer:
POLYSAR BROMOBUTYL
POLYSAR CHLOROBUTYL

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