A novel nozzle design for producing hydroentangled nonwoven materials with minimum jet-mark defects

The presence of jet-marks, or jet-streaks, on the surface of hydroentangled nonwoven fabrics, is usually regarded as an undesirable outcome of the hydroentangling process. Jet-streaks degrade aesthetic features and physical properties of the resulting fabrics. Jet-streaks are associated with low tear strength along the machine direction and non-uniform appearance. Reducing or eliminating the occurrence of jet-streaks will lead to increased use of this class of fabrics in many applications. Hydroentangling employs closely-packed single or multiple rows of high-speed waterjets to entangle and consolidate fibers or filaments in a loose (un-bonded) web. In this work, we demonstrated that a waterjet curtain made of two rows of staggered jets where the jets in the 2nd row are smaller in diameter than those in the 1st row can help minimize these jet-marks in a cost-effective manner. The optimal ratio between the diameter of the jets in the 1st and 2nd row depends on the hydroentangling pressure, as well as the web characteristics. In this study, different nozzle diameters ranging from 100 μm to 130 μm for the 2nd row were examined in combination with a fixed diameter of 130 μm for the nozzles in the 1st row. For the type of fiber-web used and the operating pressures considered, a combination of nozzles with 130 μm diameter in the 1st row, and nozzles with 110 μm diameter in the 2nd row, was found to provide the optimum setting for eliminating/minimizing the jet-marks.