Influence of Die Geometry on Fiber Motion and Fiber Attenuation in the Melt-Blowing Process

Abstract

Melt blowing is a technology for producing microfibrous nonwovens. The melt-blowing die is the key component of the melt-blowing device. In this study, a slot die and a swirl die were used to study the effects of die geometry on fiber motion and fiber attenuation in the melt-blowing process. The fiber paths in these two melt-blowing processes were recorded dynamically with a high-speed camera at a shutter speed of 3000 frames per second. The fiber path profiles, especially the whipping behavior, were for the first time obtained and presented. The recorded images were further processed to interpret the law of fiber motion and to determine the fiber velocity. A mathematical method was also constructed to qualify the fiber diameters instantly below the two dies, which are undetectable upon experimental measurement. The results show that fiber whipping in the slot-die melt-blowing process is a two-dimensional motion. In contrast, it appears as a spiral path in three dimensions in the swirl-die melt-blowing process. The swirl die creates more rapid fiber attenuation in the region near the die.

Turbulent air flow field in slot-die melt blowing for manufacturing microfibrous nonwoven materials

“…It is accessible that air with higher velocity can provide stronger attenuation of fiber and air with higher temperature can maintain molten status of fiber in longer time. However, Xie and Zeng [32] showed that higher air velocity and higher air temperature not always produced fibers with smaller diameter. In their work, a gauge air pressure of 1.0 atm created initial air velocities about 300 and 150 m s -1 for slot-die and swirl-die melt blowing; however, the fibers collected at 25-mm distance below the die have a mean diameter of 75.2 lm for the slot die, and 58.3 lm for the swirl die, for the reason that the type of turbulence also determines attenuating ratio of fiber.…”

Meltblown technology for production of polymeric microfibers/nanofibers: A review

“…Typical change in fiber diameter (expressed here as the ratio of die to final fiber diameter), is between 250 (from 0.4 mm down to 1.6 m [16]) and 667 (0.2 mm down to 300 nm [18]) for isotactic polypropylenes. It was reported that the highest fiber diameter reduction occurs at very small post die distances (typically between 10 and 20 mm) and very short times (0.05 ms) [19,20,21,22]. During fiber attenuation, very high extensional strain rates (∼10 6 s -1 ) are achieved [23].…”

“…PLEASE CITE THIS ARTICLE AS DOI:10.1063/1.5116336 FIGURE 9: 3D fiber spiral motion, images size is s 26.3 mm × 45 mm). Reprinted with permission from [22]. Copyright 2014, American Chemical Society.…”

Revealing of process–structure–property relationships of fine polypropylene fiber mats generated via melt blowing

“…A temperature too high may cause sticking of the molten fibers (Figure 4). 47 The fiber attenuation significantly depends on the air velocity (air pressure or airflow rate). Figure 3C shows the change in the average fiber diameter and confidence interval with increasing air pressure.…”