Melt blown fibers

Fiber products account for about 15% of polypropene consumption. The products range from continuous filaments for carpeting and rope to melt-blown fibers for nonwoven goods. Specific applications include outdoor carpets, yarns for upholstery and automobile seats, and replacements for canvas in luggage and shoes, disposable goods (diapers, surgical gowns), ropes, and cords. 

PP, LLDPE, and a Plastomer (a metallocene ethylene-co-hutene) For melt-spun or melt-blown fibers or fabrics Bartz et al. 1993a... 

Polypropylene, 50 wt% PP, was blended with a linear low-density polyethylene, 10-50 wt% LLDPE, and a low-molecular-weight ethylene-butene plastomer (a compatibilizer). The blends were useful for melt-spun or melt-blown fibers or fabrics. In the following patent heat sealable at 100 °C blends were disclosed. They comprised 30-70 wt% ethylene-alpha-olefin copolymer prepared using a metallocene catalyst, VLDPE or plastomer [with density p =... 

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... 

Melt-blown fibers have considerable use in disposable diapers for babies and adults, sanitary napkins, feminine hygiene, etc., since eliminating plastic backsheets, integrating wicking layers and standing leg cuffs requires the use of meltblown fabrics. 

To date, multicomponent fibers have been used much less in micro-filtration than melt blown fibers, and they are far less well known for their small size than electrospun fibers. 

The structure of melt-blown fibers can be controlled by varying flow rates of polymer melt and air, temperatures of polymer melt and air, nozzle geometry, and intrinsic properties of polymer melt. For example, higher air flow rate can... 

Only very recently the production of melt-blown polypropylene fleeces with considerably thinner fiber diameter became possible [100], thus making it possible — a low-cost hydrophilization provided — to achieve attractive properties with regard to small pore size and excellent tensile performance for use in highly automated assembly processes. 

One of the important aspects of the development of P-plastomers was the expectation that these materials were amenable to plastics processing such as fiber and film formation and yet would yield soft elastic fabrication. This combination was hitherto unknown [24]. The formation of nonwoven fabrics including spun-bond and melt-blown nonwoven fabrics as well as their laminated forms has been documented. Similarly, cast film operation to form elastic monolithic films or composite structures which are not only amenable to these processes, but also to a variety of postfabrication processes have been described. 

Polymer scientists and engineers have developed a wide variety of processes by which to convert polypropylene into useable articles. These processes include fiber-spinning, production of melt blown and spun bond non-woven fabrics, film production, blow molding, and injection molding. The following sections describe these processes and the resulting properties of the product as a function of the process. 

One of the most recent developments in the use of polyolefin fibers is in composites of spunbond (SB) and melt-blown systems. Some examples of structures being made are SB/MB, known as SM, SB/MB/SB, or SMS, and other combinations of SB and MB. The... 

G. S. Bhat, V. Narayanan and L. C. Wadsworth, Dimensionally Stable Polyester Films, Fibers, Yarns and Melt Blown Nonwovens, U.S. Patent 5,753,736 (issued May 19, 1998). 

The smaller the fiber diameter used in the prefilter, the greater the surface area for adsorption of particles and the better the retention of small particles. In the sixties, asbestos fibers were recognized as the best prefilter media. The individual fibrils were smaller than 0.01 ju and they had a positive zeta potential. However, when it was suspected that asbestos fibers presented a health hazard, fine diameter glass and synthetic polymer fibers were substituted. Unfortunately, neither media equals the performance of asbestos. Glass fibers are available in the finest diameters, but some users are fearful they may represent a similar health hazard. The trend has been to use polypropylene or polyester fiber prefilters. Melt blown or spun-bonded fibers are available in diameters near 1 ju. Multilayers of these media with appropriate calendering have resulted in surprisingly efficient prefilters. 

Among the described types of materials are those modified by Cl melt blowing. Polymer melt-blown materials are produced by a special kind of extrusion when the fibers in a viscous-flow state are squeezed through a spinneret, dispersed by a gaseous flow and then deposited on a substrate [77]. Such polymer materials can be processed jointly with liquid Cl, or the fibers can be modified by inhibiting aerosols in the course of dispersion and deposition. 

Fig. 1.17. Electron microphotograph of LDPE-based melt-blown material modified by a solid corrosion inhibitor (particles were injected into the gas-polymer flow). (1) polymer fiber, (2) a solid inhibitor particle...

Early inhibited packing films developed in the USSR in the 1970s were polymer films with glued volatile Cl on one side [76]. Further elaboration of this idea has lead to melt-blown materials whose fibers carry particles of Cl (Fig. 1.17). 

Plastic scrims are related to the same category of inhibited plastics. In a non-woven form, the inhibited film is first extruded. The polymer webbing (usually melt-blown inhibited polymer fibers) is then laminated to the film. Zerust ferrous plastic scrim is used in the manufacture of airtight packages inside which a protective atmosphere is created by VCI vapors. The fibrous scrim layer also protects packed goods from impact damage. 

Fiber processing development Unusual plastic fibers such as polyolefin fibers are produced by a spurted or melt-blown spinning technique. A variety of directly formed nonwovens with excellent filtration characteristics is produced. Original development was by... 

Nonwoven melt-blown These fibers are composed of discontinuous filaments and are smaller than those of spun-bonded fabrics. Fibers produced are very fine with a typical diameter of 3 pm. Most commercial products are made of polyester or high melt-flow polypropylene plastic. 

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