Film that splits along the machine direction, tears easily or punctures in use is a common complaint. Process settings matter, but the resin blend usually sets the ceiling on how tough the film can be.
Resin changes that make film tougher
| Change | What it improves |
|---|---|
| Butene (C4) LLDPE → hexene (C6) or octene (C8) | Tear and puncture resistance, at a modest cost increase. |
| Add metallocene LLDPE | Puncture, dart impact, clarity and sealing. |
| More LLDPE in an LDPE blend | Toughness. LDPE helps bubble stability and clarity, but too much weakens the film. |
| HMW-HDPE for thin-gauge bags | High strength at very low gauge. |
| Lower-MI grades | More toughness and melt strength. |
Process checks
- Blow-up ratio too low makes film weak in the cross direction and prone to splitting along the machine direction.
- Frost line height and cooling rate change orientation and clarity.
- Gels and contamination create weak spots that start tears.
- Gauge variation leaves thin bands that fail first.
Melt flow explained · LLDPE · HMW-HDPE · Resin for film, bags & liners