Melt Blowing
Melt blowing is a process for producing fibrous webs or articles directly from polymers or resins using high-velocity air, or another appropriate force, to form filaments and nonwoven fabrics. In this one-step process, high-velocity air blows a molten thermoplastic resin from an extruder die tip onto a conveyor or take-up screen forming a fine fibrous and self-bonding web. This process usually produces microfibers rather than normal textile fibers with diameters of 0.1 to 15 µm. Differences between melt-blown nonwoven fabrics and other nonwoven fabrics, such as degree of softness, cover or opacity, and porosity, are due to different filament sizes. Dahiya et al (7/23/2010)
Recent US Patents
3/8/2011
7,901,614
Methods and apparatus for meltblowing of polymeric material utilizing fluid flow from an auxiliary manifold
Breister et of 3M, Minnesota, developed a meltblowing device based on an auxiliary manifold to dispense a fluid between a die that is expelling polymeric fibers and an exit of a duct that is dispensing a secondary flow of gas onto the fibers. (RDC 10/10/2011).
Recent Journal Articles
Air-flow field of the melt-blowing slot die via numerical simulation and multiobjective genetic algorithms
(3520–3527) Journal of Applied Polymer Science 122 #6 (2011)
Sun et al of Donghua University, China, developed a multiobjective optimization using genetic algorithms to obtain optimum air-flow field with the lowest velocity decay and temperature decay of the air-flow field of a melt-blowing slot die. Four main geometry parameters, including slot width, head width, slot angle, and setback, were studied. The optimal results were achieved in the 50th generation with 20 individuals of each generation. The results also show that a smaller slot angle and larger slot width resulted in a lower air velocity decay and temperature decay. (RDC 9/7/2011)
Modeling the melt blowing of viscoelastic materials
(4172-4183) Chemical Engineering Science 66 #18 (2011)
Zhou et al of the University of Minnesota, Minnesota and Cummins Filtration, Wisconsin, used a slender-jet model for the melt-blown fiber to probe the effects of rheology by considering Newtonian, upper-convected Maxwell, Phan-Thien and Tanner (PTT), and Giesekus constitutive equations. Our results suggest that by combining the slender-jet approach with a Giesekus (or PTT) constitutive equation, useful engineering predictions can be made concerning the final fiber diameter, even when assuming a constant shear stress and neglecting heat transfer. Steady-state fiber profiles are found to be linearly stable, and numerical simulations indicate that the predictions from linear theory can be carried over into the nonlinear regime. Sensitivity analysis reveals that disturbances are likely to become especially amplified at particular frequencies, with elasticity reducing the magnitude of the amplification but broadening the spectrum of frequencies susceptible to large amplification. This suggests an explanation for the narrower fiber diameter distributions that are observed experimentally. (RDC 7/12/2011)