Troubleshooting guide for BOPP Film Applications
BOPP Film Troubleshooting
Problem
Probable Cause
Suggested Remedy
Temperature Setting
Temperature setting are crucial parameter for proper plastic processing ,hence one should check temperature controller, thermocouple and solid state relay(SSR)
- when you cold start the machine ,wait for 2hours.
Variation in film thickness
- Extruder surging
- Variation in die opening
- Variation in die head temperature
- Choking of screen pack or filter
- Air-knife position is not proper
- Improper setting of processing parameters for MDO (machine direction orientation), TDO (transverse direction orientation)
- Run at higher pressure, or with better mixing screw, or with cooled screw, check melt temperature and melt pressure fluctuations, increase back pressure by lowering metering pump temperature, increase first transition temperature
- Adjust die gap
- Adjust die head temperature profile correctly
- Check screen pack or filter and change if necessary
- Adjust air-knife position and flow rate of air
- Optimise stretching parameters, keep higher temperature of preheat rolls, decrease gap between stretching rolls, decrease speed of MDO rolls, increase temperature of hot air oven, check hot air blowing nozzles for blockage, check centering of tenter frame.Use resin with narrower molecular distribution (uniform stretching), use resin with comparatively lower isotactic index (uniform stretching). Lower the temperature of T-die, decrease the temperature of cooling roll, adjust the air-knife position, adjust the balance of TDO clips
Film breakage
- Resin properties
- Processing related
- Contamination
- Locate and remove the source of contamination, install a dust remover in the hopper, check and clean the surface of bag before emptying the bag in the hopper.
- Locate and remove the source of contamination, install a dust remover in the hopper, check and clean the surface of bag before emptying the bag in the hopper.
- Lower the temperature at MDO/TDO pre-heating zones, lower the processing temperature, increase the stretch ratio, use clean resin with lower gel content and free of contamination. Increase the stretch ratio, increase the temperature of cooling roll, increase the film aging temperature
Poor film stiffness
Poor mechanical strength of film
Use resin with lower isotacticity and MFI
Splits
- Poor mechanical strength of film
- Contaminated resin
- Moisture in the material
- Film thickness variation, variation in melt temperature
- Mechanical problems at tenter frame
- Jerky chains, oil drops on film, dirty clips, clip pressure is not uniform
- Stretching oven temperature too low, formation of hazy bands
- Use resin with lower isotacticity and MFI
- Use dust and gel free resin, discontinue use of recycled material, change filter pack
- Use fully dried material, increase drying capacity of hopper dryer
- Adjust die gap and extrusion temperature profile
- Lubricate rail, chain and other moving parts of tenter frame
- Decrease oil flow to chain, rails, and wipe-off excess lubricant, wind base sheet on MDO winder and check chains, clean clips or remove and replace faulty clips
- Increase temperature of preheat section of oven and MDO
Accumulation of white powder
- Processing parameters
- Resin properties
- Increase the processing temperature
- Use resin with broader molecular weight distribution and higher MFI, change the stabiliser package, check the carrier resin of master batch is same as the base resin
Water marks
Water carry over to MDO
Remove water from web completely before MDO oven
Bubbles or voids
Moisture and air entrapment in the resin, poor venting at extruder, master batch chemicals are not stable at extrusion temperature and forming volatiles
Change resin, increase transition zone temperature, increase back pressure, use high temperature stability master batch
Depression and pock marks
Chilling/casting roll too cold
Adjust chilling roll temperature, increase melt temperature
Poor optics, high haze, low gloss
- Slow cooling in casting section
- Too many haze bands present in the film
- White lines
- White spots
- Decrease casting drum temperature, or quench bath temperature, adjust air pressure in air-knife
- Increase temperature of preheat rolls and stretching rolls, decrease the temperature of cooling roll, use resin with low isotacticity, if necessary take measures to improve the dispersion of antiblocking agents
- Decrease the stretch ratio, use resin with narrower molecular weight distribution, use resin with lower tacticity for uniform stretching
- Increase the processing temperature, change the additive formulation
