Why natural rubber is rarely used in heavy tires
Why natural rubber is rarely used in heavy tires
Heavy tires are purchased mainly for their durability and re-coating capability, which is derived from the natural rubber properties used in them. The re-coating capability in the lightweight tire market is not that important. In the formulation of the compound used in aircraft tires, natural rubber is usually used because of its resistance to the heat generated during landing and take-off of the aircraft. On the other hand, in agricultural tires, because they are often used in soft and muddy soils, the formulation used is programmed based on less heat. Therefore, natural rubber is rarely used in their construction.
In the formulation of these tires, mainly oiled synthetic rubber (SBR) is used. For various reasons, polybutadiene synthetic rubber alone is not very important, but its combination with two other types of rubber improves abrasion resistance and prevents high heat in service conditions. In general, the larger the tire, the higher the NR consumption ratio. As you know, natural rubber has the maximum abrasion resistance and shows good resistance to cracking between the grooves in the tire tread area and rupture of tire treads, and also produces the minimum heat under tire service conditions.
Adhesion in the tire
Each part of the tire performs a different function and for this reason they are usually made using different rubbers or a combination of them. In general, tires are made of NR, SBR and polybutadiene rubbers and their consumption ratio depends on the type of tire and its construction and application conditions.
For example, in the case of tire treads, it is expected that it has good adhesion to the road surface and has the least erosion on the road surface. In this case, tire engineers usually make decisions based on the expected level of tire performance, and usually the creation of adhesion to the road surface in the tire due to safety issues, leads to faster erosion of the procedure.
Accordingly, in passenger tires, the best adhesion to the road surface is achieved at the cost of faster tire wear. For this reason, technologically, the application of oil SIR in the tread formulation of passenger tires is superior to NR. Sometimes a small amount of NR rubber may be used in the tread formulation of passenger tires.
Today, NR is not commonly used in passenger tires in Western Europe and the United States, but a combination of SBR and polybutadiene is used in these tires. The adhesion to the road depends on the jumping nature of the rubber used in its formulation. The higher the jumping factor in the rubber, the lower its adhesion to the road surface.
SBR has less jumping property than NR and therefore has better adhesion to the road surface. In addition, the SBR can be reduced by increasing the oily SBR, which improves traction on the road surface in that tire. The use of polybutadiene in the formulation of the mixture increases its resistance to erosion and the tendency to create groove cracks.
Bias tires do not require much adhesion to the road surface and may even be dangerous on heavy vehicles and in transporting heavy loads. In these cases, it is necessary to minimize the damage to the bias tires due to heat generated during service. The body layers of the tire are made of rubber fibers lined with polyester, nylon, rayon, aramid or wire.
The compounds used in passenger car tires are usually made from a combination of NR with SBR or polybutadiene. Viscosity control, processability, adhesion between components, resistance to crack growth and resistance to fatigue due to bending are some of the properties of synthetic rubbers. For example, in bias tires, a combination of 60% NR and 40% SBR is used, but in radial tires, the percentage of NR consumption is higher. Ordinary sidewalls (black walls) use less or no NR bias tires at all.
NR is usually used in radial tire sidewalls (50% or more (used for better tire performance. (Radial tire brackets are less thick)). NR is also used in large white or colored sidewalls, even in bias tires. Taken.
Butyl rubber, probably one of the halogenated forms, is commonly used in interiors used in interior liners. In this combination of chlorobutyl rubbers, Bromobutyl Exponidized NR is sometimes used NR. Consumed synthetic rubbers help the compound resist moisture penetration.
SBR emulsion (SDR solution, B12) is used for application in willow area, such as filler, filler, chipper and their protectors, which is sometimes combined with NR. These components must be sufficiently rigid and resistant to compaction, wear and crack growth.
It is difficult to estimate the consumption of various elastomers in the tire industry in the world. First, the choice of rubber consumption pattern is not a closed pattern, and often it is not possible to find two tire manufacturers who agree on the proportion of rubber consumption used in tire manufacturing. Second, tire manufacturers in different countries use different rubbers or a combination of them. The possibility of easy provision of NR and lack of access to SBR due to its lack also causes tire manufacturers in NR producing countries to use more NR than tire manufacturers in other countries.