ADVANCES IN CELLULOSIC PACKAGING MATERIALS
Cellulose is the most abundant biopolymer on our planet. Cellophane is a thin, transparent, and completely biodegradable film or sheet manufactured from regenerated cellulose.
Cellophane is useful for food packaging due to its low permeability to air, oils, greases, bacteria, and water. It has, therefore, been used as a food packaging material for nearly a century. Its utilization has decreased in recent decades, however, due to the increasing availability of packaging options that are often preferable to cellophane. The fact that the cellulose regeneration process generates polluting byproducts has probably contributed to this decline by creating the perception that cellophane is not an especially environmentally friendly packaging material despite being biobased and biodegradable.
The leading-edge cellulosic packaging technology of today has advanced far beyond the old cellophane technology. Advances in this technology, combined with the growing focus on increasing the utilization of biobased and biodegradable packaging materials, suggest that a comeback is likely, with new cellulosic packaging materials replacing some packaging materials derived from fossil fuel based feedstocks.
New Generation of Commercial Cellulosic Film Products
The NatureFlex™ renewable and compostable cellulosic packaging material product line of Futamura is fully commercialized. It uses cellulosic films derived from renewable wood pulp sustainably harvested in managed plantations. It provides packaging suitable for a wide variety of food service products. It is resistant to grease, oil and fats, and both microwave-safe and conventional oven-safe. The films use novel heat seal-resins on each side. They are static-free. They offer an extremely wide heat seal range for outstanding machine performance. They offer good gas barrier properties. Coatings can provide varying degrees of moisture barrier depending on the needs of the wrapped product.
By definition, “a circular economy is a regenerative system in which resource input and waste, emission, and energy leakage are minimized by slowing, closing, and narrowing energy and material loops; this can be achieved through long-lasting design, maintenance, repair, reuse, remanufacturing, refurbishing, recycling, and upcycling. This is in contrast to a linear economy which is a 'take, make, dispose' model of production.” The aspects of the development of NatureFlex™ films that have been vital to ensure that each product performs both technically and environmentally provide an example of the circular economy in action, as shown in the image reproduced below from the Futamura website.
The following image, also reproduced from the Futamura website, summarizes some facts that help provide further perspective about NatureFlex™ films.
Uncoated, semipermeable, barrier, and metalized product grades of NatureFlex™ films, as well as NatureFlex™ labels, are available.
- Uncoated films provide excellent transparency and gloss, high permeability to water vapor, good barrier to gases, aromas, and mineral oil, inherent anti-static characteristics, and excellent dead-fold. The key markets are chocolate, confectionery, and dairy.
- Semi-permeable films are semi-permeable to moisture, heat-sealable on both sides, formulated for print and conversion receptivity, and able to provide excellent barrier to gases and aromas. The key markets are fresh produce and dairy.
- Different barrier film grades provide intermediate to excellent moisture barrier, excellent barrier to gases, aromas, and mineral oil, heat-sealability, and suitability for lamination. The key markets are chocolate, confectionery, coffee, tea, dried foods, crisps/chips, home and personal care, and pouches.
- Metalized films provide ultrahigh luster and sparkle, excellent barrier to UV/visible light transmission, excellent moisture barrier, and excellent dead-fold, and are ideal for lamination. The key markets are chocolate, confectionery, coffee, tea, crisps/chips, and pouches.
- Labels provide excellent printability using traditional printing methods, high stiffness for conversion, and high gloss. The key markets are fresh produce, chocolate, confectionery, crisps/chips, and home and personal care.
Two Leading-Edge Academic Research Projects
RISE PFI, Mid Sweden University, and MoRe Research are collaborating in the Interreg project PlastiCel. The project aims to develop biobased (nanocellulose and cellulose) composites with excellent barrier and insulation properties that can be used to transport perishable goods such as fish over long distances. The packaging is coated with a thin film of plasticized cellulose and nanocellulose, providing a barrier against oxygen, while a foam core of plasticized cellulose and nanocellulose provides insulation able to maintain a low temperature in the packaging during transportation. It is speculated that the project may lead to future boxes for fish, currently made of plastic, being made instead with temperature-insulating composite materials from cellulose/nanocellulose with good barrier properties against moisture and air.
Chitin is second only to cellulose in its abundance as a biopolymer on our planet. A team at the Georgia Institute of Technology has created a new material by spraying multiple layers of chitin derived from crab shells and cellulose derived from trees to form a flexible film similar to plastic packaging. This new material has the potential of replacing the flexible plastic packaging used to keep food fresh. The team devised a method to create a film by suspending cellulose and chitin nanofibers in water and spraying them onto a surface in alternating layers. Once fully dried, the material is flexible, strong, transparent, and compostable. Chitin nanofibers, which are positively charged, and cellulose nanocrystals, which are negatively charged, appear to be working as alternating layers because they can form a strong interface. Poly(ethylene terephthalate) (PET) is the main benchmark against which the new films are being compared. At least some of the improved oxygen barrier of this new film appears to result from the facts that it has a higher crystalline fraction than PET and that the crystallites are not penetrable by gas molecules. With the amount of cellulose already produced and a ready supply of chitin-rich byproducts left over from the shellfish food industry, the team thinks that more than enough material is probably available to make the new films a viable flexible-packaging alternative. To make the new material eventually competitive with flexible packaging film on cost, however, a manufacturing process that maximizes the economies of scale will need to be developed. Additionally, while industrial processes to mass produce cellulose are mature, methods to produce chitin are still in their infancy. More research is also needed to improve the material’s ability to block water vapor.