Higher barrier properties that are required for food packaging have caused a shift in multi layer plastic film to 5/7 layers in the last few years. However, the increasing demand of barrier properties from the more demanding food industry has led to the development of 9 layer co extruded film compositions in the last 5 years. Experience with nine layers opened the door to even more complex films. 10 layers offer even more opportunities to use different structures and engineering polymers like PET etc. High-barrier films are used to extend shelf life of refrigerated products like meat, poultry, cheese, and fish-and unrefrigerated foods like powdered milk, nuts, pet food, and wine. Besides high barrier, flexibility is the most desired property- 9 layer film with thin nylon layers is relatively flexible, while 5 and 7 layer nylon barrier films are stiff because the nylon layer is thicker.

The sparing use of expensive nylon is a major attraction of 9 layer blown film as a 9 layer film splits one thick nylon barrier layer into several thin ones, enhancing barrier performance out of less nylon, and improving thermoformability. Stress cracking is avoided as thinner layers of nylon allow the deep-formed corners of a package to retain twice as much barrier material as when forming rigid 5 layer film. Thinner nylon layers also reduce film curling, a common problem with 5 and 7 layer films and allow thinner sealant layers. 9 layer film achieves more uniform gauge than a 7 layer line.

Market growth for 9 and 10 layer blown film has not been as rapid as when processors switched from three layers to 5 and 7, because there are many other ways to get the same barrier effect, including multi-layer cast film, lamination, metalizing, and coating.
The complex rheological properties of the several polymers used make it extremely difficult to process a 9 layer film. Machine builders have not rushed into the nine-layer market either. No European OEMs have ventured beyond seven-layer dies, though Windmoeller & Hoelscher in Germany and Macchi in Italy are now working on them. The difficulties faced to build and run 9 and 10 layer dies is evident in the fact that even eight years later there are still only 25 of them in the world, probably at less than a dozen companies. Brampton is the dominant supplier of lines for nine or more layers. It has delivered three 10-layer stack dies and 13 nine-layer ones, including the world's largest-31.5 in. dia.
Although IBC is a common tool to increase blown film output, usage with 9 layer films is restricted as IBC could freeze the nylon too quickly so that it doesn't adhere to the next layer and delaminates.
Changeovers are expensive, making the processor trying to line up production runs to avoid change over more than two or three extruders at a time.
The scrap generation and utilization is quite difficult. Reducing scrap is a major problem. The lines have very high output, so a production run of a specialty nine-layer film might take only two or three hours. The changeover to run the next product could take as long or longer. Sometimes less expensive all-polyolefin films can be run to complete the purging of a true nine-layer line.

Though these complexities affect the commercial viability and take off of 9-layer film extrusion system, it will give the niche product at an optimum price and this segment is expected to grow after 2010.