Water quench blown film extrusion allows the production of films with particular mechanical and optical characteristics. Windmöller & Hölscher (W&H) asserts that the wet extrusion process offers a number of advantages over systems using air-cooling, especially in thermoforming and heat-seal applications. The demonstration of asymmetric 1,100mm, 100µm seven-layer film on its Aquarex machine displayed a range of characteristics now achievable including surface feel, puncture resistance, sealing properties and transparency. The asymmetrical film structure has a thermally resistant outer layer, three inner layers for strength and stiffness and a sealable inner layer. The company said that film produced on the machine does not tend to curl, which makes subsequent processing easier.
The Aquarex blown film line extrudes high clarity barrier film with good physical strength values. (photos: Windmöller & Hölscher)
Compressing and packing voluminous mineral wool, used for heat insulation in buildings, allows for easier logistics and handling. The holding power of the packaging film is of utmost importance. W&H demonstrated a Varex blown film extrusion line producing a 180µm three-layer film based on bimodal LLDPE resins, whose thickness is achieved through in-line machine direction orientation (MDO) of the film with a ratio of approximately 1:5. Monoaxial orientation of polymer films allows their properties to be adjusted to suit particular packaging purpose. Fresh meat is, unless properly packed, vulnerable to loss of water, infection and oxidative deterioration. Barrier films have shown themselves to be effective at preserving freshness and hygiene. Another Varex blown film line demonstrated production of a 55µm asymmetric nine-layer high barrier 2m wide film, which can be heat-sealed directly to a PET tray, using a coextruded polyester sealing layer. This means that lamination of the tray film is not necessary.
Varex II producing VFFS film for processing on vertical tubular bag making machines
W&H said that the highlight of its in-house Expo was its new Varex II blown film line for VFFS film for consumer and industrial packaging, which was configured to produce three-layer film. The exhibit produced film intended for processing on vertical tubular bag making machines and demonstrated changeovers from 2,200mm, 40µm film for frozen food to an 1,880mm, 75µm film for wood pellets. Using the company’s Easy-Change and Easy-Wind technologies, changeover was completed without interrupting production. The newly developed resin types are characterised by enhanced mechanical strength as well as improved processing properties, while allowing for 25% downgauging. The new Varex II has a modular design, which enables it to be tailored to a range of user requirements, production environments and product portfolios. W&H further asserts that the modular concept allows for retrofitting with new modules and technologies as need arises. Varex II is available with working widths up to 3,600mm and for up to 11-layer films. It is designed for outputs up to 1,500kg/h. Extruder sizes include 50, 60, 70, 90, 105, 120 and 135.30D. Die diameters range from 120 to 900mm.
The market for sterilisable stand-up pouches is growing fast and highly economical, efficient production is essential. W&H’s Filmex system demonstrated production of five-layer, 2,000mm CPP film for this application, at approximately 500kg/h. The demonstration showed that film thickness could be reduced to 60µm, which offers material savings of 25%, compared to conventional production.
The Filmex five-layer cast film line with Filmatic TC winder for the production of CPP film for pouch applications
Also on display was a Filmex cast film coextrusion line for nano layer “superpower stretch” film, with a width of 3,000mm. Equipped with seven extruders, it produced a 33-layer 12µm composite film at 600m/min and output of around 1,200 kg/h. The film is used on high-speed stretch wrap systems.
The Filmex high-speed seven-layer cast film line with nano layer feedblock and Filmatic PS winder for the production of “superpower stretch” film
As well as extrusion machines, W&H exhibited a range of cooling systems, printers, sleeve presses, hemming and tubing systems.
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