Film processing practices

Converting thin fi lms Thinner, lighter constructions

The continued push for thinner and lighter constructions has been a trend in the packaging and pressure sensitive market for the last 20 years. With changes in the type of film used in the label face (PET vs BOPP) and continued reductions in the thickness of the PET liners, we have seen a reduction in total overall caliper of 30 to 50%.

Down gauged films and liners continue to be the trend in the industry for pressure sensitive decoration. Thinner films allow for improved sustainability, increased yield and reduction in manufacturing costs and storage without sacrificing the performance requirements of the label. Thin clear films normally have the potential for improved shelf appeal as well (reducing the label profile on the for an enhanced “no label look”.)

While there are many advantages to thin films there are some best practices that should be made when converting and applying these . Here are some converting tips and best practices when using thin film stock.

Web handling

• All rollers should be clean and in good working order.

• Older nip rolls should be checked to ensure that durometer (hardness) has not changed signifi cantly. It is not uncommon for nip rollers to slowly increase in durometer becoming harder and smoother, causing slippage of the thinner fi lms over time.

• Anti-static devices at both rewind and unwind are recommended.

• The press should be well grounded. This would include any external unwind or rewind stations.

• The lowest tensions should be run while still maintaining good registration.

• It is recommended that six (6) inch cores be used on both the unwind and the rewind of the press. Six inch cores allow for better roll tension build on the incoming rolls and on the converted rolls. They allow a little more operating window than a three inch core on the taper and tension. • Thinner fi lms often need a sharper peel plate to cutting and tooling consistently dispense the label from the liner. A flat edge ground to an approximation of 0,8mm thick is ideal (not • Most die manufactures offer tighter tolerances on fl exible a rounded tip). dies and magnetic cylinders on the thinner PET fi lms. These include the 23 microns and even 19 microns • On and requiring the “no label look”, liners. The quality of the anvil roll should also be wipe down pressure should be applied as soon as the evaluated. label contacts the surface of the container to minimize air • The magnetic cylinders used should be clean and in entrapment. This is commonly achieved with rubber good working order squeegees, rollers and belt systems. The goal is to remove as much air as possible at • No damage to magnetic cylinder • No high spots the point of application to the container. • No loose magnets • Rewind tensions on the applicator may need to be • Tooling dies to the actual label stock is strongly increased slightly to assist in initial dispensing from recommended. the peel plate. • Razor type slitter knives give the cleanest cuts. If razor • Reducing the label fl ag on the peel plate may be knives are not available due to safety concerns, a shear required to assist in consistent application. slitting system is recommended. If a score slitter is used, • For clear pressure sensitive labels, soft foam rollers ensure pressure to knife is consistent. The highest quality or brushes are not recommended for laminating to score blade should be used and careful attention should the container (do not effectively remove air at point be paid to blade wear and possible grooving of the roll of application and can be the cause of air bubble used as an anvil. entrapment and haze). • Ensure the lowest amount of heat buildup in the die station by maintaining the bearings and ensuring bearers are lubricated and wipers are functioning as designed.

Finishing

• Ensure good roll build by starting with as low a tension setting as possible that allows for a good roll build. Tapering to a lighter tension as the roll is made is recommended. • An initially low and then tapered roll build will have – Less ooze – Less impression of label being transferred • A hard roll that allows no movement at core will likely have both adhesive ooze issues and label impression issues.

Application

• Applicators should ensure that label detectors (sensors) are calibrated or suitable for fi lms (especially if utilizing clear fi lms with clear fi lm liners). For the highest speed and highest accuracy, a single capacitive sensor would be best, but caution should be used if the label is metalized or has cold foil present where the sensor is wto be lined up. Conductivity of fi lm negatively affects this type of sensor. www.upmrafl atac.com some versatile alternatives toPPand PE. some versatilealternatives more aboutfi learn Functional, attractive,andsustainable – The manyadvantages of fi lm labelstockanddiscover lm

05/2017 ENG 1356