PA6 to enhance blown film processing for flexible food packaging

30-Oct-13

The potential for polyamide 6 in blown film for flexible food packaging is further enhanced with the introduction of Akulon® XS by Royal DSM. Thanks to its improved crystallization properties, Akulon XS has an extended processing window, providing new opportunities in designing co-extruded multi-layer as well as monolayer film structures. Processors notice significant improvements in production when using the new Akulon XS. As awareness of the need for food waste reduction and shelf life extension grows, demand for barrier films for flexible food packaging continues to increase. Many barrier films are coextruded on blown film lines, and structures with seven, nine and even 11 layers are now quite common. This technology provides a cost-effective way of combining various functionalities, such as barrier, printability, sealability and impact resistance. Polyamide 6 (PA6) is a very interesting option for use in such films, owing to its good barrier properties and its mechanical strength. The high crystallization rate of polyamide 6, however, can limit its processing window. Processors have to either compromise on productivity, or obtain improved processability by blending the PA6 with special, and more expensive, amorphous polyamides or polyamide copolymers. This reduces the cost-effectiveness of the film. Akulon XS from DSM resolves the issue. It crystallizes much slower in the film bubble than conventional PA6—matching the crystallization rate of other material layers. This creates a more stable bubble and gives processors more leeway in their processing conditions. The film is also more stretchable, so less force is needed to achieve the same blow-up ratio (BUR), or the same force can be used to produce a bubble with a BUR between 7 and 10 % higher. There are also fewer wrinkles in the flat film. Even though slower crystallization creates larger crystals that might be expected to produce a less clear film, tests on full-scale production lines have shown that there is virtually no discernible difference in the optical properties of films made with a benchmark film-grade polyamide and Akulon XS. In fact, all properties of the film in use are the same as in film made with standard PA6.