Nylon cords tire reinforcement

Tire 1. Truck tire reinforced with nylon 6 cord Tire 2. Truck tire reinforced with PET cord. 

Tire cord n. A textile material used to impart the flex resistance necessary for tire reinforcement. Tire yarns of polyester, rayon, nylon, aramid, glass, or steel are twisted to 5-12 turns/in. Two or more of these twisted yarns are twisted together in the opposite direction to obtain a cabled tire cord. The twist level required depends on the material, the yarn linear density, and the particular application of the cord. Normally, tire cords are twisted to about the same degree in the S and Z directions, which mean that the net effect is almost zero twist in the finished cord. 

Cyclohexane is converted to cyclohexanone to produce caprolactam, the principal feedstock for nylon-6, which is used to make tire cord for tire reinforcement. 

In the 1940s rayon was used almost exclusively in tires. It was difficult to adhere rayon to rubber mechanically because of the smooth surface of the rayon filaments. Fortunately, two Dupont Co. chemists, W. H. Charch and D. B. Maney found that incorporating a resorcinol-formaldehyde thermosetting resin into a rubber latex made a cord adhesive which gave excellent adhesion of rayon to rubber carcass compounds. The same RFL cord adhesive was also used when nylon was introduced as a tire reinforcing material in 1947 and when glass fiber was introduced as belt material in belted bias and radial tires. 

Nylon, an aUphatic polyamide, was introduced as a commercial tire cord in 1947 and grew in usage to - 5.4 billion kg/yr (- 2 billion Ib/yr) in the 1990s (10,11). Nylon-reinforced tires use nylon-6 poljmier (polycaprolactam) fibers as well as nylon-6,6 (poly(hexamethylenediainine adipamide)) fibers. Nylon tire cords are characterized by extremely good fatigue resistance in compression and good adhesion to most mbber compounds with simple RFL adhesives. 

Polyester fibers can be blended with natural fibers such as cotton and wool. The products have better qualities and are used for men s and women s wear, pillow cases, and bedspreads. Fiberfill, made from polyesters, is used in mattresses, pillows, and sleeping bags. High-tenacity polymers for tire cord reinforcement are equivalent in strength to nylon tire cords and are superior because they do not flat spot. V-belts and fire hoses made from industrial filaments are another market for polyesters. 

A tire is a textile-steel-rubber composite the steel and textile cords reinforce the rubber and are the primary load-carrying structures within the tire. Because of the performance demands of fatigue resistance, tensile strength, durability, and resilience, seven principal materials have been found suitable for tire application cotton, rayon, nylon, polyester, steel, fiberglass, and aramid the latter three materials find primary usage in the tire crown or belt region. 

The most common textile bonding compositions are, of course, the RFL (resorcinol-formaldehyde-latex) dips used to adhere tire carcass rubber to cord reinforcing members. A typical RFL composition calls for a latex terpolymer of styrene-butadiene-vinyl pyridine as well as the resorcinol and hexamethylene tetramine. Some natural rubber latex or regular SBR latex may also be added. The R F resin which forms in situ is able to react chemically with rayon by methylol etherification of the cellulose s hydroxyls. Similar reaction is likely with the amide groups of nylon fibers as shown in Figure 7. 

An RFL dip consists of an aqueous resorcinol formaldehyde resin liquid with a ruhher latex. The RF resin is used to achieve good adhesion to the organic fiber substrate whether it be rayon, nylon, or polyester. The rubber latex portion can be a natural rubber latex or a styrene butadiene vinylpyridine (terpolymer) latex or even a neoprene latex. This rubber latex is present to achieve good adhesion with the rubber matrix itself. So the RFL allows good adhesion between the rubber and the textile cord reinforcement whether it is used in the manufacture of passenger tires, truck tires, off-the-road tires, power transmission belts, V-belts, timing belts, or various hose products. 

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