Swiss technical-textile maker Oerlikon Barmag introduced its high-modulus low-shrinkage (HMLS) yarn at Techtextil 2015 offering a polyester to be used in tire cord.
One of two companies worldwide that produces machine solutions for the production of HMLS yarn—the material is tear resistant, but elastic and temperature stable—used predominantly in high-speed tires. Oerlikon Barmag’s polyester tire cord has almost completely replaced viscose fiber rayon for ecological reasons.
As a result of contact with the road, tires are subjected to a constant friction, which heats up the tires and consequently increases the internal air pressure; the higher the speed, the higher the tire temperature and the pressure within the tire. The high-modulus polyester reinforces tires with dimensionally stable HMLS and permits high speeds with a high degree of safety.
HMLS yarn acquires its properties in the spinning process. High speeds in the production process guarantee a stable arrangement of the molecules within the polymer, which forms the actual filament. The internal structure of the molecule chain determines the dimensional stability of the subsequent yarn.
Manufacturing this challenging material in an economical manner requires stable process technology and high-quality components. These determine the requirements for the spinning plant, the godets and the winders. The higher the spinning and winding speeds, the more sensitively the filaments react to irregularities in the polymer melt, which can cause breaks in the filament. Oerlikon Barmag HMLS systems work with the EvoQuench quenching system, in which filament bundles with up to 600 individual filaments are evenly spun, cooled and spin-finished and in this way allow homogenous threads of between 1000 and 2000 denier to be manufactured.