Demand for sustainable materials in flexible packaging has grown steadily from both retailers and consumers, and manufacturers across the food industry are working to align their operations to this trend. 

However, as they make the switch, many companies find that they were unprepared for the reality that sustainable films can behave differently than current films and their form fill seal equipment is not set up to accommodate it.

Machinery considerations can be a challenge when incorporating sustainable materials, but they do not have to deter food producers from moving forward with the process. Reduce, reuse, recycle has long been the mantra of the sustainability movement, and adopting recyclable materials into flexible packaging also can be done with “re-”: recognize, realize, refine.

Recognizing the Situation

For sustainability purposes, films can be sorted into one of two categories: non-recyclable legacy materials and recyclable mono-materials. Films made from legacy materials are the traditional choice for form-fill-seal applications. They are composed of different kinds of plastics laminated together in multiple layers. Mono-materials, as the name would imply, only consist of one kind of plastic, and all the layers are made from that same material.

While the single strain of plastic in mono-materials makes them recyclable, it also makes them more difficult to process through packaging equipment. Part of the appeal of packaging with legacy materials is that the different layers of plastic have different melting points – providing a large process window. As the interior layers melt under the seal bar to close and secure the package, the exterior layers with the printed imagery stay solid for a polished final look. However, with only one type of plastic, mono-materials do not have that same variety in reactions to temperature – i.e. a smaller process window. Unless the similarity in melting points is accounted for in the equipment, line operators will likely produce packages with either incomplete seals or melted, distorted prints.

Realizing Innovation

Luckily, innovators within the packaging industry have developed technologies to effectively incorporate mono-materials into automated packaging lines. Some of the developments have been to the film itself. 

Though film producers cannot include more than one kind of plastic in recyclable films, they can make modifications to each layer to influence its performance. By manipulating components in the polymer, engineers have created mono-material film that performs more like legacy material. This innovation has led to materials with an increased process window that allows the inner layers to melt and create the seal while the outer layers remain unaffected.

In addition to adjustments to some of the materials on the market, small changes to packaging equipment can help optimize it for any recyclable film. New seal bars have been developed with temperatures curated specifically for mono-materials, providing a quality seal without compromising the look of the package. Automatic tensioning systems are also available to provide consistent tension, so the exterior layers are not pulled too tightly. These solutions detect when film is stretching too far and adjust to ensure best results.

While many new machines have these systems built in, older equipment often is not set up to account for recyclable films. As a solution, some packaging equipment manufacturers have developed modular designs so new innovations can be incorporated into existing lines. This option is much more cost- and time-effective than replacing the machine, reducing the barriers to adopting sustainable practices.

Refining Your Solution

Finding the best option for each application may seem overwhelming, but line operators do not have to do it alone. Working directly with equipment manufacturers when setting up a sustainability infrastructure is the best, most efficient way to match up film needs to the operation’s form fill seal machine capabilities. 

Some suppliers will offer testing support with facilities where users can run different options on different equipment to see what produces the best final product. This allows the customer to try out different combinations without any interruption to their production lines. It also takes the guess work out of investing in solutions to optimize a line for sustainability, as the operator will have already identified a successful formula before any modifications are made.

Ultimately, the best tool for implementing sustainable materials into a packaging line is an ongoing partnership with the equipment manufacturer. When food producers openly communicate about their goals and future aspirations, the machinery provider can work with them to make them a reality.