Melt blown processes

This process resembles the spun-bond process with the major difference in the quenching of the filaments by hot air at high speed. This leads to very thin fibers (1-5 pm diameter) and hence to thin nonwoven structures. Crucial for these parameters are both air velocity and temperature as well as melt viscosity. 

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Spunbond and Melting Blown Process Charts, KASEN Corporation Japan. http //www.kasetL co.jp/English/product/line/work.html... 

Nonwoven fabrics account for more PP usage than any other single fiber application. There are three types of nonwoven fabrics thermobonded, from staple fibers spunbonded and melt-blown. The spunbonded and melt-blown processes are discussed below. The fabrics from each process differ from each other in properties and appearance, and often combinations of two types are used together. Spunbonded fabrics are strong, whereas melt-blown fabrics are soft and have high bulk. 

The fibers formed in the melt-blown process are very fine and allow for the production of lightweight uniform fabrics that are soft but not strong. Fabrics from fine melt-blown fibers can be used in medical applications because they... 

Keywords bulk continuous fibers (BCF), crystallinity, drawing, elasticity, elongation, fiber-forming polymer, fiber monofilament, low oriented yam (LOY), melt blown process, melting, monofilament, multifilament silk, orientation, partially oriented yam (POY), staple fibers, spinning, spunbonded fibers, stmcture, technical fiber, tenacity, textile fiber, texturing. 

The addition of the forces out of the air speed for the downsizing of the filaments and out of drag forces created within the See air jet is typical for the melt blown process. This effect of combined forces results in a variation of filament diameters along the filaments, so the measured filament diameter distribution is relatively broad. Melt blown fabrics are mainly used for their barrier, filtration and their absorption properties. 

The equipment used for melt making is not completely linked to extrusion machinery, since the used melt viscosity in this process is low compared to other spinning processes, in the range of less than 100 pa, eg, PP is used in an MFR rage of 125—3000 (230/2.16). Resins used in the melt blown process are characterized by the already mentioned low viscosity and still some elastic properties in order to be able to spin into filaments. There are no restrictions, so polyolefins, polyesters, polyamides and polyurethanes, as well as bitumen or cellulosic solutions, are possible to process via the melt blown process into filaments. Even high melting point polymers such as Polyphenylensulfid (PPS), Polysulfon (PSU) or even Polyetheretherketon... 

Several companies present new processes or modified melt blown processes on the market. Most of these processes are relatively new and still under development. 

The melt-blown process was developed in the 1950s and put to commercial use during the 1970s [163, 164, 166]. The initial patent design of Exxon [167] was executed later by the melt-blown plant system known as Automatie/Foume [168, 169] and by the Reicofil melt-blown system of Reifenhauser GmbH (Germany). 

In the melt-blown process, the molten polymer moves from the extruder to the special melt blowing die. As the molten filaments exit the die, they are contacted by an airjet of high temperature and high velocity. This airjet is drawn rapidly and, in combination with the quenching air, it solidifies the filaments. The entire filament-forming process takes place within 7 mm of the die. Die design is the key to producing a quality product. 

The principal advantage of the melt-blown process is that it can make fine filaments and produce very light weight fabrics with excellent uniformity. The result is a soft fabric with excellent barrier properties, meaning effective filtration characteristics and resistance to penetration by aqueous liquids. This property is vital in medical applications as concerns on blood-borne diseases increase. 

Melt-blown process Continuous filamentary webs Microfibers (0.03 dtex)... 

Fagan, J. R, and Wadsworth, L. C., Melt Blown Processing and Characterization of Halar Fluo-ropolymers, Textiles and Nonwovens Development Center, The U. of Teimessee, pp. 1-15, Feb. 28, 1991. 

Figure 4.2 Schematic illustration of the melt-blown process.

Lewandowski Z, Ziabicki A, Jarecki L. The nonwovens formation in the melt-blown process. Fibres Text East Eur 2007 15(50) 64-5. 

Figure 6.20 Spun-bonded and melt-blown process line (Courtesy of Reifenhauser)...

The back moistening and permeability of the covering nonwovens are dependent on the covering as well as the inside layer. The nonwovens (Chapter 6) are produced by four different technologies dry, wet, spun-bonded, and melt-blown processes. The latter two processes are single-stage processes that allow the production of a finished nonwoven made of raw materials. 

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