Innerliner compound

The sidewall compound is compounded to protect the ply and must possess resistance to weathering, ozone, abrasion, and tearing while providing excellent flex fatigue resistance. The innerliner compound must provide good air-permeation resistance and resist moist/hot air aging. The inside of a hot... 

Halobutyl rubber is used mostly to make the innerliner compound for today s modern tubeless tires. This is because halobutyl rubber is compatible with general-purpose rubbers, can be covulcanized with them, and can impart good adhesion to them. Virtually all tubeless tire innerliners use halobutyl rubber. 

The technical alternatives to halobutyl rubber in tire innerliner applications are very poor, in the short term. However, with the development of new innerliner compounds based on DIMS (see below), a substitution could be achieved long term with much development work. 

If not available, a user could revert back to the thermoset innerliner compound based on halobutyl rubber, which might increase the cost of production and hurt tire performance. 

Kaolin is primarily used in the rubber industry as a filler and is frequently used in the calcined form. It is being widely used in innerliner compound in the tubeless tire industry. Use of kaolin in glass fiber reinforced thermosets improves surface quality, reduces warpage, and lowers crack formation. Kaolin is used in polyvinyl chloride (PVC) wire coating because of its good electrical insulating properties. Surface-treated calcined kaolines are used for tire wheel cap made from polyamides (PA) and greenhouse films from LDPE [7[. 

Wire cords are particularly subject to degradation of their adhesion values by moisture. To combat this, halogenated butyl (HIIR) is used in tire innerliners because of its property of low air and water vapor diffusion rates. Moisture is present in most air pumps and many tires are mounted with water left in the tire on mounting. For these reasons tires and tire compounds are tested extensively at simulated aging conditions in the laboratory and on test vehicles before they are sold to the customer. 

Ground mbber has replaced reclaim in many tire applications including treads, carcasses, innerliners, subtreads, and bead components. It is also used in mechanical goods, footwear, solid tires, mats, and retreads. Cryogenically and wet-ground mbbers which are of smaller particle size can be used at moderately bigb levels and still allow compounds to be processible. 

Critical to a tire s life cycle performance is the ability to maintain air pressure. Tire innerliners composed of halobutyl-based compounds exhibit very low air and moisture permeability. Therefore, tires built with the proper selection of compounds can reduce the rate of premature failure, again delaying entry into the scrap tire and solid waste streams. 

Halobutyl rubber (HIIR) is used primarily in tire innerliner and white sidewalls. These elastomers are best for tire air retention owing to lower air permeability as well as aging and fatigue resistance. The chlorinated (CIIR) and brominated (BUR) versions of isobutylene isoprene rubber (HR) can be blended with other elastomers to improve adhesion between HIIR compounds and those based on general purpose elastomers, and improve vulcanization kinetics [16]. 

N650 High modulus, high hardness, low die swell, smooth extrusion Tire innerliners, carcass, belt, sidewall compounds, seals, friction compounds, sheeting... 

N660 Medium modulus, good flex fatigue resistance, low heat buildup Carcass, sidewall, bead compounds, innerliners, seals, cable jackets, hose, soling, EPDM compounds... 

Talc is used in tires in white sidewall compounds to provide a smooth appearance to the buffed sidewall. The large platelets of talc provide a barrier to gas and moisture permeability in compounds, which allows talc to be used in applications such as hydraulic and automotive hoses, barrier films, and tire innerliners. 

The primary application for halobutyl rubber is in tires. The combination of low gas and moisture permeability, high heat and flex resistance, and ability to covulcanize with highly chemically unsaturated rubber has secured the use of these rubbers in the innerliners of tubeless tires. Passenger tires use chlorobutyl alone or in a blend with 20 to 40% natural rubber. High-service steel-belted truck tires use 100% bromobutyl innerliner compoimds. Chlorobutyl is also used for truck inner tubes for its superior heat resistance compared to butyl rubber. Halobutyl rubbers are added to sidewall compounds for improved ozone and flex resistance, and to certain tread compounds for improved wet skid resistance and traction. 

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