Tire rubber butadiene-based

New synthetic rubber polymerization technologies replacing older plants and increasing world consumption are two reasons new production facilities are being buUt around the world. Goodyear Tire Rubber s 110,000-metric tons/y butadiene-based solution polymers went onstream in 2000 in Beaumont Texas. Goodyear s 18,200-metric tons/y polyisoprene unit went onstream in 1999 in Beaumont. Sumitomo Sumika AL built a... 

Between the 1920s when the initial commercial development of mbbery elastomers based on 1,3-dienes began (5—7), and 1955 when transition metal catalysts were fkst used to prepare synthetic polyisoprene, researchers in the U.S. and Europe developed emulsion polybutadiene and styrene—butadiene copolymers as substitutes for natural mbber. However, the tire properties of these polymers were inferior to natural mbber compounds. In seeking to improve the synthetic material properties, research was conducted in many laboratories worldwide, especially in the U.S. under the Rubber Reserve Program. 

The most common adhesive system used for bonding continuous fibers and fabrics to rubber is resorcinol-formaldehyde latex (RFL) system. In general, RFL system is a water-based material. Different lattices including nitrile and SBR are used as the latex for the adhesive system. 2-Vinylpyridine-butadiene-styrene is the common latex used in the adhesive recipe. RFL system is widely being used in tires, diaphragms, power transmission belts, hoses, and conveyor belts because of its dynamic properties, adhesion, heat resistance, and the capacity to bond a wide range of fabrics and mbbers. 

Figure 15. Behavior under strain of an unvulcanized tire ply (conventional recipe) based on NR (natural rubber 100%), 1R (synthetic cis-7,4-polyisoprene 100%), BP/1R (a 50/50 blend of IR and txans-butadiene-piperylene copolymer).

Plasticizers. These materials are added to reduce the hardness of the compound and can reduce the viscosity of the uncured compound to facilitate processes such as mixing and extruding. The most common materials are petroleum-based oils, esters, and fatty acids. Critical properties of these materials are their compatibility with the rubber and their viscosity. Failure to obtain sufficient compatibility will cause the plasticizer to diffuse out of the compound. The oils are classified as aromatic, naphthenic, or paraffinic according to their components. Aromatic oils will be more compatible with styrene-butadiene rubber than paraffinic oils, whereas the inverse will be true for butyl rubber. The aromatic oils are dark colored and thus cannot be used where color is critical, as in the white sidewall of a tire. The naphthenic and paraffinic oils can be colorless and are referred to as nonstaining. 

The discovery of the ability of lithium-based catalysts to polymerize isoprene to give a high cis 1,4 polyisoprene was rapidly followed by the development of alkyllithium-based polybutadiene. The first commercial plant was built by the Firestone Tire and Rubber Company in 1960. Within a few years the technology was expanded to butadiene-styrene copolymers, with commercial production under way toward the end of the 1960s. 

The elastomers and elastomer blends used in tire compounds, and particularly tread compounds, are thus equally important to the structural design parameters of the tire (Table 4.7). A properly designed tread compound will ensure the tire can meet its performance targets. Tread compounding materials fall into one of five general categories polymers, fillers, protectants, vulcanization system, and various special purpose additives. Elastomers for tread compounds are typically natural rubber (NR), styrene-butadiene rubber (SBR), polybutadiene (BR), and in some instances isobutylene based polymers for winter and special performance tires. 

PB is the polymer of 1,3-butadiene and is a synthetic rubber. Natural rubber is plant-derived and is a polymer of isoprene. Isoprene is also a 1,3-diene but has an additional methyl group. The main uses of PB are in the manufacture of tires in the transport industry and also as one of the components of materials based on a polyst Tene or styrene-acrylonitrile copolymer. 

The dienes often compete with NR in many applications. Choices often are affected by relatively small changes in price. Tires consume about 70% of the polymers based on isoprene (synthetic and natural) and butadiene. Polychloroprene, while not suited for tires because of heat buildup, is the most widely used oil-resistant rubber. It is much more resistant to oxidation at high temperatures than the hydrocarbon dienes or SBR. More than any other polymer, it fits in the paradoxical category of being a general-purpose specialty rubber. 

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