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Article by Nampak 18 June 2013

Latest technologies reflect demand for barrier and speciality films

The Nampak group’s policy of investing in the best technology where it is demanded by market developments is reflected in three recent investments by Nampak Flexible.
1. The installation of the first 7-layer co-ex film extruder in sub-Saharan Africa at its Pinetown, KwaZulu-Natal, factory, at a cost of over R30m.
2. Laser scoring technology, installed in the Cape Town operation.
3. Multiple investments in pouch-making machines in Cape Town, which also allows it to produce spouted pouches.

By far the largest Nampak Flexible investment has been in the state-of-the-art Windmöller & Hölscher co-ex film extruder. The machine is 18 metres tall and the roof of the factory had to be lifted to fit it in. The only other 7-layer machine in Africa is in Egypt, but the Pinetown is machine features more advanced technology.
The initial spur to invest in the co-ex film extruder - called "The Monster" by staff - was simple: Nampak Flexible had reached capacity in its production of film and was having to contract out work.

The Monster, which has been producing since December 2012, has a capacity to produce 550kg per hour of film, almost as much as the rest of all the other extruders - two 3-layer extruders and a 1-layer extruder - at the Pinetown plant put together.
The investment also reflects increasing demand for barrier films and speciality films. Management initially considered buying a 3- or 5-layer machine, both of which are now relatively common in the industry. But while these machines would have allowed it to make a high-quality film with gauge control, or barrier film, they would not allow for film which encompassed both of these qualities.

The decision to go for a 7-layer machine means that Nampak Flexibles has "leapfrogged", says MD Clinton Farndell.

The larger number of possible layer permutations allowed with seven layers means, for instance, that lower cost nylon barrier material can be used, allowing for the phasing out of laminate layers.
More layers also allow for better balancing of the laminated final product. Seven layers can be symmetrical or asymmetrical.

Extrusion process and benefits
Basically, a laminate film extruder has three, five or seven hoppers (depending on whether it is a 3-, 5- or 7-layer machine, [Status]). The raw materials for the various layers are fed into these hoppers. Colour may also be added into the raw material for any layer in which colour is required. Adhesive (tie, [Status]) layers may be included where a particular layer, like a nylon layer, does not naturally adhere to other layers.
The extrusion manufacture process requires raw material resins that are then heated, mixed and homogenised, and the hot material is spun upwards using updraught air, into the film.

The new Windmöller & Hölscher machine stabilises the bubble particularly quickly.
The machine operates at gauge control for final laminated film of 3%, compared to 10% on older machines, says Farndell - which for the customer means a much more even film with better sealability.

The machine also has purge assist, with low purge times. Obviously, with seven layers, there are many different materials, and rapid purging of them to prepare for the next batch of production is important. A new batch can be up and running in under 30 minutes, according to Anand Padayachee, general manager of the Pinetown plant.

The Windmöller & Hölscher machine also has recipe memory, antistatic systems, etc. It is technically supported from Germany online via an ISDN line into the system.
Because of all its automatic functions, the machine has lower energy consumption than older models.

More efficient layering allows for reduced microns and further savings.
In some applications, because of barrier capabilities, metallised layers can be replaced with nylon. This is better for recyclability - currently many multilayer flexibles are classified as number seven in the recycling system (meaning that there is no recycling stream for them in SA, [Status]).
In food and other products, spoiling of the product packed is typically caused by ingress of oxygen or water. The barrier layer used to prevent oxygen ingress is normally EVOH; while nylon usually prevents water ingress.
In the food industry, high barrier films are mainly used in packaging meat and cheese products. Customers want the convenience of longer shelf life and they also aspire to recyclability.

Typically meat or cheese packaged without any barrier film will last 3-6 days. With the correct barrier films, the same products can last up to six weeks - depending upon the amount of barrier film, the product itself, moisture, whether it is vacuum packed, and whether it is opened.
Hitherto, most 5-layer film and all 7-layer film used in packaging food products in SA have been imported. Nampak Flexible is therefore currently designing 7-layer products - mainly for meat and cheese.

Laser scoring for easy opening has become particularly important as part of the larger trend for convenience. Nampak Flexible’s Baasel Rofin is a patented laser system, burning one million holes per second that are consistent in shape, diameter and spacing. Hole diameters are from 50 µ up to 300 µ.

This process can be accomplished with winding speeds of up to 800 metres per minute.

Farndell says easy opening is about packaging functionality and enhanced product features. One aspect is optimal handling for older people - but generally there is better acceptance of products which have laser scoring. Such products can also accommodate complex opening functions.
“Laser is optimum because it is a non-contact processing tool with minimum thermal influence on the film. It allows for constant depth of the laser scribing/scoring line, reproducibility and yet higher flexibility for product changes,” he states. “Quality is exactly controlled and scoring may be set for one, two, three or however many layers are required (for instance six layers for a 3-layer laminate, without damaging the traditional aluminium barrier layer which could be layer 2 in a complex structure. Different shapes and curves are also on the menu.”
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