Evaluation of technologies for extruding barrier films

Market studies and surveys prove that multi-layer barrier films are the new hot topic with branded good owners. There are several proven technologies on the market, but which one is right?PackagingFilms organised a webinar dedicated to the topic “Extruding barrier Films – Comparing blown, cast, biax (annular) extrusion technologies” to answer this and many other questions.

By Sebastian Reisig

On September 25, the flexible packaging industry witnessed a PackagingFilms first: a technical webinar, presented by Macro Engineering & Technology Inc. The topic was “Extruding Barrier Films” presented by Dr Harinder Tamber, director of R&D at Macro Engineering. He has over 25 years of experience in polymer processing in film and sheet extrusion and has worked on the machinery supplier side and the film producer side of the industry.

Different technologies, same product?

Blown or cast or bi-ax (annular) processes are used to make multilayer barrier films. For a converter, distributor and retailer in the food, medical and industrial packaging sectors, a number of multilayer film properties such as optical, mechanical, thermal and barrier are important for packaging different products.

It is important to correlate equipment vs. polymer processing/materials to understand multilayer film properties provided by blown, cast or bi-ax processes.

The, aim of the presentation is to discuss equipment, process and polymers (resins) and to understand why and how in each process different multilayer film properties occur, and attempts are made to explain these on a scientific basis.

Tamber divided the presentation into four categories. He began with fundamental information on polymer resins, such as their long chain structure, melting characteristics of a resin and cooling the melt by air or water (into thin film). He continued by discussing the effect of the cooling method on the formation of crystalline and amorphous phase and crystal size (number and density) in the cooled film. The presentation provided basic information on optical, mechanical, thermal and barrier properties of a single polymer film/resin as is provided per ASTM, and only gave descriptions of the key components, of blown, cast and bi-ax multilayer film processes. Tamber also explained how to the utilise ‘basic polymer’ and ‘basic information on film properties’ discussed above; analysis and comparison of multilayer film properties fabricated from these three processes (blown, cast and bi-ax) using polymers such as Nylon 61, EVOH-382-4, PVdC5,6, PETG7, Tie8 and LLDPE9 is provided.