Materials Multilayer
Materials Multilayer transparent barrierfilms Four key players in the bioplastics industry - Eurotech Extrusion Machinery, NatureWorks, Nippon Gohsei and Sukano - have successfully processed a multilayer transparent biobased barrier film. This allows packaging manufacturers to count coextruded film structure as a potential replacement for conventional fossil fuel-based structures in dry food packaging. Flexible multilayer plastic packaging design remains a major challenge, as most conventional multilayer films are neither recyclable nor compostable. As of today, there is a lack of recyclability for this kind of packaging that still makes up over 75 % of the food industry usage. Understanding this gap in the market, four key players in the bioplastics industry have joined together to find a solution. Eurotech Extrusion Machinery (Tradate, Italy), NatureWorks (Minnetonka, Minnesota, USA), Nippon Gohsei (headquartered in Osaka, Japan) and Sukano (Schindellegi, Switzweland) have now successfully processed a multilayer transparent biobased barrier film. Ingeo resin processed into a film is already used in many types of flexible packaging. Using Ingeo provides for a reduced carbon footprint, as well as compostability as an end of life option. For higher gas barrier requirements, a coating or a metallization surface treatment of the film is typically required. However, the need for this coating or metallization can be eliminated through the use of a barrier polymer to produce a coextruded structure. This provides an additional, new option for packing foods which require an extended shelf life, while still offering clarity and compostability. The coex film processed at Eurotech used a K5A 5 layer blown film lab machine in a configuration using two extruders 25 mm, and three extruders 20 mm, including the die lip of 100 mm diameter and 1.4 mm gap. The total film thicknesses of 45 µm, 280 mm width, contains Ingeo PLA 4043D from NatureWorks and is used in the inner A layer, with an outer bubble layer E including Sukano masterbatches processing aids. These PLAbased Sukano masterbatches were specifically designed for this application. The tie layers use BTR8002P and the barrier layer uses G-polymer both from Nippon Gohsei. This combination of formulation and process conditions yielded a stable bubble, excellent film transparency, and good roll quality. Testing showed that the use of Sukano masterbatches offered increased melt strength, and therefore better processability, good transparency and better adhesion during sealing. Mechanical properties were also maintained. As an additional benefit each material used in the film has either been tested and certified or assessed to be biodegradable and industrially compostable according to European norm EN 13432. Less film sticking was managed via the use of slip agent biobased masterbatches, which increased the processing window and ensured good processability conditions and a lower COF (coefficient of friction), therefore conferring better film properties for secondary fabrication steps. For the barrier layer Nichigo G-Polymer, the World’s first Extrudable High Barrier Amorphous Vinyl Alcohol Resin, was used. This provided key benefits in packaging, such as excellent gas and aroma barrier and high transparency, while supporting compostability and recyclability properties of the final film produced. Outstanding water solubility for solution coating barrier applications and extrudability were also evident. The G-Polymer barrier is so effective that it can replace Alu-foil in many packaging applications. And even at 4mm thickness of mono-layer G-Polymer, transparency was glass-like. The tie layer BTR8002P gives high adhesion between layers, maintaining high transparency The achievement of this multilayer transparent biobased barrier film allows packaging manufacturers to count multilayer film structure as a potential replacement for conventional fossil fuel-based structures in dry food packaging such as lid films for coffee capsules or lidding films for cups and trays, flow packs, trays for snacks, and biscuits packages. And it may even extend to certain humid foods such as ham, fish, and meat when used with proper packaging design. MT www.sukano.com | www.natureworksllc.com www.nippon-gohsei.com | www.eurexma.com Bio-Barrier with Nichigo G-Polymer Existing Barrier (PP/EVOH/PP) Barrier Layer [µm] 13 12 Humidity in Barrier [%] 26 4 WVTR [g/capsule day] OTR [cm 3 /capsule day Air] 38°C 90%RH 0.059 0.007 23°C Inner Dry, Outer 50%RH 0.0002 0.0008 42 bioplastics MAGAZINE [04/18] Vol. 13
From Science & Research Bioplastic made of cactus (Photo: EFE) With the juice of nopal, a plant of the cactus family and basic ingredient in Mexican cuisine, a Mexican researcher has created a natural biodegradable plastic that can reduce pollution. Sandra Pascoe, from the Universidad del Valle de Atemajac (Univa) in Guadalajara, western Mexico, developed this plastic after several experiments with this cactus often used in salads and traditional Mexican stews. At first, she experimented with dried pieces of nopal, which she mixed with additives, but the process was slow and the physical and chemical characteristics changed a lot. “The material oxidized quickly”, she told the Mexican news agency EFE. Sandra then began to use the juice of the species’opuntia ficus indica’, the most common among the nopal trees and widely used as a vegetable. Later she took the so-called opuntia megacantha, which is famous for its fruit called tuna, very juicy but covered all over with thorns. “Basically, the plastic is made from the sugars in the nopal juice, the monosaccharides and polysaccharides it contains,” the researcher explained. Sandra pointed out that the cactus has a very viscous consistency that comes from these sugars, pectin and organic acids and “that viscosity is what we are taking advantage of so that a solid material can be produced”, she said. In her lab at the Department of Exact Sciences and Engineering, Pascoe glycerol, natural waxes, proteins and colorants with the juice after it has been strained to remove its fibers, creating a formula that is then dried on a hot plate to produce thin sheets of plastic. This process was registered with the Mexican Institute of Intellectual Property (IMPI) in 2014 and the development became possible with funding from the National Council of Science and Technology (Conacyt) of Mexico. The researcher told EFE that with the support of the campus of Biological and Agricultural Sciences of the University of Guadalajara, she is in the process of investigating the degradation characteristics of this plastic, i.e. in what conditions and how long it takes to decompose in a natural environment. “We have done very simple degradation tests in the laboratory. We have put it for example in water and we found that it does disintegrate. However, we still need to do a chemical test to see if the material has really been completely disintegrated. We have also done tests on moistened compost soil and the material is also disintegrated”, she added. Sandra said that in addition to shopping bags, the nopal juice plastic could be used for applications such as cosmetic containers, imitation jewelry and toys. Tests are currently being conducted to establish how much weight the plastic can bear which will help determine what other products it could be used for. She explained that projects have already been done at student level to generate prototypes “very simple and it is clear that there is potential to do a lot more with this material”. At the moment thermal properties and the density of the plastic are being determined to learn how much weight it can resist in case of being transformed into bags and other products. The next step on the path towards commercialization will be to make or buy a machine that can produce prototypes of the plastic bags in order to market them to businesses. The innovation is in the process of being patented. Once this is granted by the IMPI, it will be possible to generate agreements to transfer the technology to interested companies, Sandra Pascoe concluded. MT Source: EFE tinyurl.com/cactusplastic (Photo: Kerstin Neumeister) bioplastics MAGAZINE [04/18] Vol. 13 43
