Many of the blown film processors I work with have asked if we have a purge compound that will help expedite a color or material change on the fly without losing the bubble. Until very recently, the answer had always been 'no.'
It may be surprising, but the active ingredients in many purge compounds which provide the necessary cleaning power to get the job done are the culprit. Additives such as abrasives, blowing agents, and other components will minimize the integrity of the bubble causing it to fail. You can still get a sufficient cleaning but will have to restring the line in the process. In many cases, restringing the line can take just as much time and effort as cleaning it in the first place. This is not ideal.
Much to the relief of some of my friends in film extrusion, there are some recent developments in purging compound grade development that provide the best of both worlds.
In the past several years, a number of products became available that manage to do both. Their proprietary formulations provide excellent cleaning power with the ability to maintain the bubble. The results are minimizing time, scrap and cost of transitions with minimal effort. The two best examples of this crossover potential are found in Asaclean's NL Grade & UF2 Grade.
These types of grades require neither lowering or nor increasing heats. They are used at your normal processing temperatures. In most cases, simply follow behind the resin or color your trying to displace at normal processing speeds. They don't have any complicated steps to follow and are safe for screen packs, melt pumps, mixers and dies.
Additionally, blown-film-friendly purging compounds are excellent for shutdowns. They will stabilize single or multi layer lines for hours enabling you to perform maintenance if needed as well as weekend or holiday shutdowns. They will displace the production material effectively greatly reducing the potential of those little black specks of carbonized material.
Blown film processors know they require very large quantities of material for production. These new developments in the field can help reduce some of the headaches in an application that previously had no easy fixes.
Ready to reduce your production downtime to protect your profits? Learn more about how purging compounds and process efficiency work in tandem.