Conversion of Recycled Polymers/Fibers into Melt Blown and Spunbonded Nonwovens
Bhat, Gajanan S.
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Melt blowing being a simple one-step process for converting polymer directly into a nonwoven fabric, is ideally suited for processing of several recycled plastics. The process uses hot air to draw the fibers and does not require precise, individual control of each filament as in the conventional fiber sprnning processes. It was demonstrated that recycled polyethylene terephthalate (PET) can be melt blown into nonwoven webs, but with poorer performance properties, due to the larger diameter of the fibers. Three methods of improving the melt blown processing of post-consumer recycled PET and the performance properties of the melt blown nonwoven webs produced from them were explored. They were, (1) using undried PET instead of dried PET, (2) blending recycled PET with other polymers, and (3) processing recycled PET at a higher temperature. The webs produced with undried PET had smaller fiber diameter, higher tenacity in the machine direction and lower air permeability. The greater drop in intrinsic viscosity indicated that more hydrolytic degradation occurred during processing of the undried PET. The webs produced from blends of recycled-PET/PBT as well as recycled-PET/low IV-PET had smaller fiber diameter, lower air permeability and higher tenacity in machine direction than those of 100% recycled PET webs. There were no * Currently with Techmer PM, #1 Quality Circle, Clinton, TN 37716. notable property changes caused by increasing the die temperature alone. The webs produced by increasing the barrel temperature as well as the die temperature had lower fiber diameter, lower thickness, lower air permeability and higher tenacity in machine direction. Intrinsic viscosities of webs which had improved performance properties were also considerably lower, indicating a significant drop in molecular weight of the recycled PET. Recycled PP form several sources were investigated as candidates for meltblowing and spunbonding. Pelletized waste form spunbond line was used in both spunbonding and melt blowing studies. SMS fabrics were also pelletized and meltblown at our facility. To explore the feasibility of using the J & M meltblowing line with the EG unit to remelt the waste web and feed it with the molten virgin polymer stream coming from the extruder, a 1000MFR virgin PP resin and fabrics produced from that polymer were used. Fabrics were characterized in all the cases for their performance properties. Some of the relevant data is reported here. It was observed that in most of the cases, fabrics with good properties can be produced at high throughputs, thus reusing all of the plant waste.