Nanoval Technology—An Intermediate Process between Meltblown and Spunbond

Abstract

The idea of ”Nanoval technology“ origins in the metal injection molding for gas atomization of metal powders and the knowledge of spunbond technologies for the creation of thermoplastic nonwovens using the benefits of both techniques. In this study, we evaluated processing limits experimentally for the spinning of different types of polypropylene, further standard polymers, and polyphenylene sulfide, marked by defect-free fiber creation. A numerical simulation study of the turbulent air flow as well as filament motion in the process visualized that the turnover from uniaxial flow (initial stretching caused by the high air velocity directed at the spinning die) to turbulent viscoelastic behavior occurs significantly earlier than in the melt-blown process. Modeling of the whole process showed that additional guide plates below the spinneret reduce the turbulent air flow significantly by regulating the inflow of secondary process air. The corresponding melt flow index of processible polymer grades varied between 35 g·10min−1 up to 1200 g·10min−1 and thus covering the range of extrusion-type, spunbond-type, yarn-type, and meltblown-type polymers. Hence, mean fiber diameters were adjustable for PP between 0.8 and 39.3 μm without changing components of the process setup. This implies that the Nanoval process enables the flexibility to produce fiber diameters in the typical range achievable by the standard meltblown process (~1–7 μm) as well as in the coarseness of spunbond nonwovens (15–30 μm) and, moreover, operates in the gap between them.

The Impact of the COVID-19 Pandemic on the Amount of Plastic Waste and Alternative Materials in the Context of the Circular Economy

“…The degree of filtration of the nonwoven is dependent on the diameter of the fibres and, therefore, the diameter of the pores. Standard melt-blown nonwovens contain fibres with a diameter of 1-7 µm, while spun-bond contains fibres with a diameter of 10-30 µm [94,101]. The spun-bond nonwoven fabric manufactured by the authors can be used in a protective face mask as a protective layer of the melt-blown nonwoven fabric.…”

“…At this stage, the fibers are loosely laid and only pre-bonded into the webbing. It is necessary to use a calendar at a certain temperature to bond the fibers into a nonwoven [93,94]. The parameters of the process are shown below.…”

Influence of Rheological and Morphological Characteristics of Polyhydroxybutyrate on Its Meltblown Process Behavior

“…PHB1 (Figure 5a) has the lowest number and weight average of molar mass and shows the lowest viscosity, right above the melting temperature (see Table 1), but also has a quite stable viscosity over time compared to PHB2 (Figure 4b). PHB1 is already located within the desired viscosity range for the meltblown process [54], which is set by typical residence times in the extruder between 5 and 10 min and an upper viscosity limit between 100 and 150 Pa•s −1 . PHB2 with a higher initial viscosity also "enters" this range, albeit only after about 500 s, showing a faster degradation as indicated before by the TGA curve by the earlier onset of decomposition (Section 3.1.1).…”

“…Indeed, the conditions required for the production of fibers via meltblown are different to yarn spinning or spunbond processes and more "harsh" for the polymer concerning degradation [54] and they are not established for PHAs so far. For the classical meltblown process, the setting is based on the development of Exxon Mobile Corp. (Irving, TX, USA) in the 1960s [55].…”

Investigate the Processability of Biobased Thermoplastics Used in Nonwoven Fabrics

“…Moreover, the Nanoval process offers 25 approximately 60% energy savings compared to conventional meltblown lines under identical processing conditions. 26 Numerous investigations have been conducted on the attributes of biobased thermoplastic polymers. 27−30 Nevertheless, most of these biopolymers have been produced on a limited laboratory scale.…”