Water-Quenched Line Said To Produce High-Clarity Film

December, 2001

Blown Film:

Water-Quenched Line Said To Produce High-Clarity Film

At the K Show in Dusseldorf last month, Brampton Engineering introduced theAquaFrost, a water- quenched, multilayer blown film line said to allow users to produce blown film with clarity that will compete with cast film. By using water as a cooling medium AquaFrost is said to produce film with high clarity, balanced orientation and deep draw thermoformability at cast-film output rates.

The company built a five-layer production scale AquaFrost demonstration line at its Blown Film Technology Center and says it can produce film with "clarity and softness not seen before in multilayer blown film."

The line uses a 'streamlined' co-extrusion die that is said to allow for rapid structural changeovers, temperature isolation, minimum degradation and long periods between cleaning. In operation, the molten polymer expands as it exits the die and then freezes as it passes down through a water-cooling chamber. From there it travels to the collapsing frame and then to a vertical oscillating haul-off. The use of an oscillating haul-off for gage randomization is reportedly an advantage overcast film lines because it makes large flat rolls.

The film clarity is said to be the result of much higher heat transfer rates, which minimizes the time the melt spends in the critical crystal-growth temperature range, especially in nylon. Because of this, AquaFrost allows the use of the less expensive blown film process to produce films with the clarity of cast films.

The balanced orientation of films produced on the AquaFrost causes approximately equal shrinkage in both directions, reducing the distortion in the end product, similar to conventional blown film.

The softness of the film is also said to allow deep draw thermoforming of vacuum packs. The line operates at 37 lb/hr/in. of die circumference, which is reportedly 2.5 times the rate of conventional upward blown film rates and competitive with cast film rates.

Visitors to Brampton's booth at K saw thermoformed packs with as much as 5 in. draw on 10-mil film for 5-lb vacuum packs.

Brampton's AquaFrost line is available for trials. Lines from monolayer up to ten-layer AquaFrost systems can be built to customer specifications.

Brampton Engineering
Brampton, ON
Canada Circle 101