Today, sustainability is at the heart of how our societies are developing. In the packaging industry this focus is prompting brand owners to move away from metalized or multi-material structures and to look for more recycling-friendly solutions. This is driving change and encouraging innovation among material suppliers.
Milliken’s line of UltraGuard Solutions is part of this innovation, bringing improved barrier performance to PE films, opening up the opportunity for greater freedom when it comes to layer design. UltraGuard Solutions bring barrier improvement to polyethylene effectively reducing the permeation of any substance.
Flexible packaging design challenges
Flexible packaging design involves the complicated task of combining several layers to achieve the right balance of properties required to protect a package’s contents. Historically, several different materials (mostly plastics) were used across the layers to accomplish that, including nylon, PET, PP, PE, aluminium, EVOH, and PVDC, among others.
But this multilayer approach to packaging proves problematic when it comes to tackling the challenge of plastic waste. Multi-material packaging can often make a product more difficult to recycle because the different materials are not necessarily compatible and can negatively impact the quality of the recyclate.
There are many guidelines to encourage the use of mono-material structures, including from the well-known Ellen MacArthur Foundation, whose report “The New Plastics Economy: Rethinking the Future of Plastics,” states: “…non-reusable packaging must be easy to separate into single material types; mono-materials are to be used if possible; only recyclable materials must be used.” However, in the mono-material packaging scenario, meeting the technical requirements of the packaging becomes a much more challenging task.
HDPE, LDPE, LLDPE and UltraGuard – winning combinations
In mono-material polyethylene-based structures, the use of high-density polyethylene (HDPE) comes to mind when higher levels of moisture barrier are required. Due to its higher crystallinity, HDPE has a naturally higher barrier than LDPE or LLDPE. With the addition of UltraGuard, HDPE is one of the best choices for structures needing good moisture barrier. The use of HDPE can potentially compromise some properties such as toughness and stiffness but UltraGuard can help to mitigate that.
Several structures require blending different types of PE in a single layer. In some cases, LDPE is added to an HDPE layer in order to get a more stable bubble or reduce wrinkling. The addition of LDPE can significantly reduce the barrier properties of the film, which can be compensated for by using UltraGuard.
When converters want to take full advantage of HDPE properties, instead of blending they could include a core layer of that material. The use of UltraGuard can help minimize the thickness of the HDPE layer needed to achieve a certain level of barrier, also minimizing the loss of other physical properties.
UltraGuard reduces the transmission rate of all permeants which, besides water and oxygen, might include aroma, alcohol, solvents and grease. In one experiment, the transmission rate of olive oil was also measured, and a lower transmission rate was found, shown by a higher number of days needed for the oil to permeate through the film. And, by using Milliken’s UltraGuard Solutions for PE, products that require barrier protection, such as pharmaceuticals, nutraceuticals and nutritional drinks, can be packaged in thinner bottles that are made with this Milliken technology.
The latest technology for packaging recyclability and sustainability
By improving the barrier of polyethylene, UltraGuard Solutions bring significant value and flexibility of design to converters and brand owners, as well as addressing challenges around packaging recyclability and sustainability.
UltraGuard Solutions improve the barrier against various types of permeants, deliver the flexibility to optimize layer thickness or film barrier performance and allow a better balance of properties in HDPE/LLDPE or HDPE/LDPE blends.
The challenge of combining traditional performance attributes with recyclability attributes is only going to increase in importance and Milliken will continue to focus on bringing next generation technology solutions to the market to address this growing need.