Nylon Tyre Cord: Nylon tyre cord is made from high tenacity continuous filament yarn by twisting and plying. There are two major types of nylons used as tyre cord, i.e. nylon-6 and nylon-6,6. The properties of nylon-6 and nylon-6,6 vary marginally and are controlled by the manufacturing process, type of stabilisers and additives used. In India only nylon-6 is produced commercially for tyre cord. Thetypesofnylon-6tyrecordusedinIndiaare840/2,1260/2,1260/3, 1680/ 2 and 1890 / 2 where number indicates denier of ply / no. of plies in the cord. The denier per filament is 6.
Tyre Cord: The other materials used as tyre cord are cotton, rayon, polyester, fibre glass, steel,aromatic polyamides. Each of these materials has its own merits and demerits. The major criteria for acceptance of any material in tyre are its tensile strength, dimensional stability, durability, thermal stability, hysteresis and adhesion. Tests and actual application conditions have shown that although other cord materials meet one or more specific requirements, nylon by and large meets the desirable requirements for almost all the performance criteria.
Tyres: The tyre cord fabric provides the tyre its fundamental properties such as shape, size, load carrying capacity, abrasion resistance, fatigue resistance, etc. A tyre is a composite of cord and rubber. There are three varieties of tyres viz. bias-angle tyres, radial tyres and bias-belted tyres. They differ in the way the tyre fabric plies are laid inside the tyre.
Manufacturing Process: The manufacturing process for nylon-6 tyre cord can be broadly divided into following production steps: (a) Polymerisation of caprolactam to manufacture nylon chips. 1
(b) Extraction and drying of chips. (c) Melt spinning of chips to manufacture nylon tyre yarn. (d) Preparation ofcordfrom tyre yarn by twisting and plying. (e) Recycling of nylon-6 waste. 0.1.5 Polymerisation: Nylon is made by polymerisation of caprolactam with certain additives like amino acids and dicarboxylic acid salts and certain heat stabiliser such as copper based organic compounds. The polymerisation process involves ring opening polycondensation and polyaddition reactions. All the three polymerisation reaction steps are equilibrium reactions. A typical process of polymerisation of nylon can be either a batch or a continuous process. The continuous process, developed after the batch process was commercialised, offers simplicity of design, ease of operation and control and high capacity. An optimal polymerisation process would involve two stages, wherein, the first stage involves pressure at high initial water concentration. In the second stage a rapid transition from high water content to a low water content is achieved by release of pressure and subsequent application of vacuum. Industrial grade nylon-6 with relative viscosity 3.2 to 3.5 has higher degree of polymerisation compared to textile grade nylon-6 with relative viscosity 2.2 to 2.6. 0.1.6 Extrusion and Drying of Chips: The nylon chips are washed to remove water soluble impurities and then dried. The process maybe batch or continuous. 0.1.7 Melt Spinning: The polymer chips are melt in extruder. The molten polymer is then spun through a spinnerette. The molten filaments are quenched or cooled by a laminar flow of air. The spin finish is applied on filament and then wound on spin bobbins and drawn to make tyre yarns. In the conventional process, the spinning and drawing was done in two steps. In the spin-draw process, a step is reduced compared to 2-step conventional process. As a consequence, some sources of process disturbances are eliminated which results in improved yarn uniformity.
Preparation of Cord: Nylon tyre yarns are then twisted in S or Z direction and plied having 2 or 3 plies to form a tyre cord.
Recovery of Nylon-6 Waste: Depending on the quality of waste, any of the following...