How to solve Film adhesion, Water carry over, and Uneven dispersion in Blown Film?

It is well known that plastic-filler masterbatch can reduce the cost. Almost all plastic products use filler masterbatch, and blown film products are no exception.

Blown film is one of the most popular plastic manufacturing methods worldwide. As it offers end-products great uniform properties regarding the length and width, it is specifically preferred in the packaging industry.

In the process of using filler masterbatch for film blowing, it will occur some troubles. It may come from the user’s own process, machinery, etc., and may also come from the blown film filler masterbatch. Let’s find out in this article.

1. Issue: Blocking in blown film (film adhesion) 

This is a common problem encountered by many manufacturers. Blocking the net is the adhesion of two adjacent layers of film.

– Cause: Indicates the winding tension or corona treatment level may be too high

– Troubleshooting:

  • Reduce winding tension
  • Lessen treatment levels
  • Inadequate film cooling; reduce cooling roll temperature or reduce line speed
  • Inadequate levels of anti-block additive; increase anti-block

2. Issue: Water carry over, “raindrops”, or gray streaks

– Cause: Indicates potential moisture in resin stream

– Troubleshooting:

  • Identify the cause of moisture in the material handling system
  • Check water condensation on the extruder feed section (hot, humid environment)
  • Ensure filler masterbatch are dry; check moisture content with heated moisture balance
  • Ensure dryer, if used, is functioning properly

3. Issue: Uneven dispersion

– Cause: Indicates poor mixing or uneven melting

– Troubleshooting:

  • Residence time inadequate for accurate mixing; increase backpressure/residence time
  • Melt temperature inadequate for accurate mixing; lower temperature to increase shear
  • Change the raw materials or the recipe of the ingredients; reduce the percentage of filler masterbatch.
  • Evaluate the feed screw design; change or modify if needed
  • Evaluate the resin rheology compatibility
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