Sealing PBAT / PLA films: a narrower window, handled.

Why degradable films seal differently

PBAT/PLA blends have lower melt strength and stiffer behavior than polyethylene, and the blend ratio is not a fixed spec — it varies between film batches and suppliers. A parameter set that sealed beautifully last month can crack this month on a new roll. The response is not operator heroics; it's a narrower, instrumented process: find the window with test seals, hold current steady so the window doesn't wander, and re-check when the film batch changes.

What helps in practice

• Start from test seals
  A short matrix of temperature steps on your actual film finds the window in minutes — guessing from PE experience doesn't.
• Current control, not hope
  The controller must hold the setpoint through batch changes and speed variation; drift is what turns a good window into intermittent cracks.
• A parameter library per film
  Record the working window per film type and blend — so the next roll starts from data, not trial and error.
• Honest verification
  Seal strength checks on YOUR film, before the production run — not after the customer complains.

What we need from you

• Film
  Structure (PBAT/PLA ratio if known, additives), thickness, supplier if fixed.
• Bag & seal
  Bag type (T-shirt, flat, gusseted), seal width, sealing position.
• Line
  Cycle rate or line speed, and how often film batches change.
• Sample
  A short roll of your film — we run test seals on the bench and return the window and settings.

Controlled warm-up — the controller holds the setpoint