Machine Design

PPA helps stretch film caster spool up production

About 100 to 1,000 ppm of Dynamar FX 5911X PPA added to olefin and nonolefin thermoplastics helps eliminate melt fracture, lowers extruder torque, and reduces die build-up. PPA is said to work at far lower concentrations than conventional processing additives such as hydrocarbon waxes, fatty acid derivatives, and petroleum oils.

A recent polymer-processing additive (PPA) helps a maker of cast stretch film boost throughput by 30% from 600 to 800 metric tons/month. Dynamar PPA from Dyneon LLC, Oakdale, Minn. (a 3M company), is a free flowing polymer formulated for castfilm operations and other high-molecular-weight, high-viscosity, polyolefin conversion processes.

Mexico-based film maker Polyrafia processes up to 1.5 metric tons/hr of resin through 310°C dies. Such extreme conditions degraded the resin, formed gel, microcarbon, weld lines, and made it difficult to control film thickness. The line required constant adjustment and had to be shut down periodically to clean die and chill rolls, a time-consuming task.

But, the addition of about 100-ppm Dynamar PPA to the masterbatch eliminates these problems and improves film optical and mechanical properties as well. The PPA also lowers the die pressure for processing. The PPA-enhanced masterbatch, along with a new cast-film machine from Batten Gloucester Engineering Co., Mexico, lets Polyrafia pump out 381-cm-wide film at rates of 213 m/min.

Dyneon LLC, 6744 33rd St. N, Oakdale, MN 55128, (800) 863-9374,

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