Everyone makes a purge, but not all purges are the same. Purges get a bad name because some manufactures don’t put a lot of thought into the chemistry or the process, or if they do put some thought into the process they just want to do it cheaply and get a bunch of barefoot resin, mix it together call it a “purge” because people are just going to make a patty and throw it away.
However, at Phoenix Plastics we put a lot of actual thought and science into our purges. We are chemical compounders, and we can add and mix as many things as we want into our purges to address the changing resins and problems film manufacturers face.
Film extruders always need Broad Distribution resin for their physicals, stretch, elongation, gauging, etc. These resins can have very big and very little polymer chains. When you add sheer and heat histories to these chains, they can shred which can cause some to acquire very low molecular weight. These small molecular weighted chains melt and migrate out to the surface first and lead to dye build up, residues, and waxes.
Heat histories are always killers of resins. They cause more damage to polymer chains which leads to degradation, charring, and black specs. Double this process if you are using any form of regrind or recycled material, because the degrading cycle has already started eventually becoming Carbon. Certain pigments like carbon black, which likes to bind to steel, or Titanium dioxide, which loves to plate out. In a very short time, your barrels and flights of screws are coated in contamination.
Running only resin as a purge may be enough but usually only deposits a thin coating of resin that flows over the carbon. Eventually, these also flake off causing black specs or particles that get stuck in the die.
Having a specialty purge that takes these processes into consideration will greatly decrease wear and tear on machines, provides protection of resin, and limits down time.
The Cel-Span 385 was designed to:
*solubilize pigments and loses plate out.
*compatibilize and re-incorporate all the small Molecular weight (low ends).
*expanders to permeate into the microcracks on the screws, barrels, and dead spaces.
*resin blend and scouring minerals to scour all the loose particulates and gels that are causing the die lines.