High-performance treads

Volumewise, natural rubber represents about half of all the rubber used in producing tires today. Typically, natural rubber is used as a blend with either SBR or BR in tire rubber compounds. NR/SBR compound blends are used in the tire carcass coat, cushion gum, earth-mover retreads, light truck treads, bead filler, chaffer rim flange, and motorcycle treads. NR/BR compound blends are commonly used to make passenger tire treads, sidewalls, high-performance treads, camelback, and heavy-duty truck treads. 

Cap-plies are more commonly used on high-performance car tires. Having a circumferential cord direction they provide an additional contractive force. They are also found more often now in normal-performance tires where they can act as a barrier layer between the tread and the casing to restrict migration of the chemicals from the tread into the belt. ... 

Typical processing data for reactors with a carbon black output of 10000 t/a (1250 kg/h) of tread black and of 14 000 t/a (1750 kg/h) of carcass black are listed in Table 28. These data show that the total mass put through the reactor amounts to 10-16 t/h. Although this is done at high streaming velocities (up to 800 m/s) and high temperatures (up to 1800 °C), modern high-performance reactors have lifetimes of 2 years and more. 

N121 121 132 Tire treads for high performance passenger cars... 

N234 120 125 Tire treads for high performance cars, tank pads, conveyor belt covers... 

PROPERTIES OF SPECIAL INTEREST Standard emulsion SBR is a general purpose rubber. Most widely used synthetic rubber in the world. Better tire tread-wear and aging properties than natural rubber. Good abrasion resistance and crack initiation resistance. Poor in tack and heat build-up. Physical properties are poor without reinforcing fillers. Solution SBR is a speciality rubber and more expensive than emulsion SBR. Solution SBR with high vinyl and styrene levels is used in high performance tire treads to improve wet traction. Also used as impact modifier in plastics and as thermoplastic elastomers. 

In the tire industry, a tackifier is used in many places. During the forming process, some parts such as the tread and side wall of a tire, are attached together by the tackifier. In the construction of high performance tire, for example the racing car tire, the incorporation of a suitable tackifier could improve the road gripping properties. 

The increase in natural rubber usage translates into approximately 21kg per tire for a radial construction compared with approximately 9 kg found in a bias truck tire. Natural rubber compounds also tend to find use in covers of high-performance conveyor belts where a similar set of performance parameters such as those of a truck tire tread compound are found. Low hysteretic properties, high tensile strength, and good abrasion resistance are required for both products. 

Highly dispersible Tire casings. Tire treads Tire treads High performance tire treads... 

Compound Economy line tire tread High-performance Low rolling tread resistance Radial medium truck... 

Table 4.16 high-performance passenger tire tread ... 

I 4 Compounding and Processing of Rubber/Rubber Blends Table 4.16 High-performance tire tread compound. 

Blends of halobutyl or brominated poly(isobutylene-co-p-methylstyrene) with high diene rubbers are used in tire sidewalls and tread compoimds (137-139). In sidewalls, ozone resistance, crack cut growth, and appearance are critical to their performance. Properly formulated blends with high diene rubbers that exhibit phase cocontinuity yield excellent sidewalls (140). The property balance for tire tread compounds can be enhanced by the incorporation of a more damping halobutyl or brominated poly(isobutylene-co-p-methylstyrene) rubber phase (141). Improvements in wet-, snow-, and ice-skid resistances and in dry traction without compromises in abrasion resistance and rolling resistance for high performance tires can be accomplished by using bromobutyl or brominated poly(isobutylene-co-p-methylstyrene) up to 30 pbr in tread compoimds (142). 

TESPT remained the industry standard coupling agent for sulfur cured rubber into the 1990s. With the development of HDS came expanded applications for silica-based compounds, particularly in high performance passenger tire treads which needed a combination of tread wear, low rolling resistance, and good wet traction (73). This combination of performance attributes can be simultaneously optimized to unique levels with silica. Recipes with 50-100 phr silica were now permissible and desirable. 

The Bayer Tear Analyser is described, and examples are presented of its use in predicting the cut growth performance of rubber compounds for high performance car tyre treads, car and truck tyre breakers, radial truck tyre treads and truck tyre inner liners. Good correlation between the test results and the service performance of various tyre components is demonstrated. The application of the machine in optimising tyre inner liner formulations based on bromobutyl robber and blends of bromobutyl and butyl rubber is also described. 6 refs. 

Diesters are also used in proprietary high performance BR/SBR tire-tread formulations at approximately 10 phr to reduce hysteresis, improve hot traction in racing tires, increase flex life and other requirements of track and street car and motorcycle tires. 

Polybutadiene is produced by solution polymerisation, and one important feature governing the performance of the resultant polymer is the cis 1,4, and 1, 2 vinyl contents. High cis 1,4 polymers (>90%) have a Tg around -90 °C, and hence exhibit excellent low temperature flexibility only exceeded by the phenyl silicones. They also exhibit excellent resilience and abrasion resistance unfortunately the high resilience gives poor wet grip in tyre treads, and hence this rubber finds limited use as the sole base for such compounds. 

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