Foam PLA in cold chain
Foam PLA in cold chain transportation By: Steven Wu & Henter Lee Guangzhou Bio-plus Materials Technology Co., Ltd. Guangzhou, China Incubators are widely used in cold chain transportation, especially in today’s life of highly developed e-commerce and direct supply of fresh products. How to deliver fresh foods to consumers has become a special concern of many e-commerce platforms, fresh food producers, and logistic companies. In traditional cold chain transportation expanded polystyrene (EPS) and expanded polypropylene (EPP) incubators or cross-linked polyethylene (XPE) insulation bags are generally used. However, these incubators are very difficult to recycle after being delivered to consumers, so they are discarded as garbage in most cases, which makes it a plastic pollution risk. Some enterprises in Europe and New Zealand make and sell EPLA (expanded PLA) incubators. However, due to the high melting point and low crystallinity of PLA, the fusion strength between PLA foam beads is not high enough during steam forming. The resulting EPLA incubators are, therefore, not firm and good-shaped compared to those made of EPS or EPP. Meanwhile, both material cost of PLA and manufacturing cost of bead and steam forming are fairly high, which leads to slow commercialization of EPLA products. Guangzhou Bio-plus Materials Technology, has been committed to the development of PLA foaming materials and applications for many years. Their modified PLA material for foaming has been industrialized and successfully used in many applications such as food boxes, trays, coffee cups, and other products. One of their recent application innovations is to make biodegradable and biobased foldable incubators: first continuously extruded PLA foam sheet is laminated to corrugated cardboard or kraft paper, to form an insulation board (as shown in Figure 1). Then foldable incubators are produced using the traditional manufacturing process for corrugated cartons. This innovative PLA-foam incubator has many advantages compared to other incubating materials. Similar to traditional cartons, the composite insulation board can be simply folded into an incubator, which is convenient for operators to fold. It can also save the operating space for on-site packing as well. This similarity to carton makes storage and transportation also incredibly easy. The 40 cm x 40 cm x 40 cm incubator can hold goods over 15 kg and bear weight of 200 kg on its top. It is made from 4 mm thick PLA foam sheet with an expansion rate of 15 times; Kraft paper of 300 g/m²; and is laminated with water-based starch glue. The expansion rate of PLA foam can be 5-30 times, with thicknesses of 1-6 mm, and the scraps during PLA sheet production can be recycled, so the cost of PLA foam sheet is well controllable. For example, the cost of an above-mentioned PLA-foam incubator is about three USD. The material has better insulation properties than traditional plastics. A comparison of cold insulation and hot insulation between the foldable insulation incubators of PLA foam and the traditional EPS over 12 hours is shown in Figures 2 and 3. Both the outer materials, corrugated paper and kraft paper, as well as the PLA foam are either recyclable or compostable. If white cardboard is used as the outer material of the incubator, exquisite printing can be realized so that it can be applied to high-end thermal insulation packaging, such as outer packaging boxes for ice cream and fresh meat. Fully automatic production equipment can be used from foam sheet extrusion to board assembly. In terms of the extrusion foaming machine of 130/150 screw, 250 kg of foam sheet can be produced in one hour, which can be converted into foam sheet that is one meter wide, 5 mm thick at an expansion rate of 10 times, and 400 meters long. This would be around 300 incubators in the size of 40 cm x 40 cm x 40 cm. PLA-foam foldable incubators are currently being tested by some e-commerce and cold chain transportation companies in China. Bio-plus is further improving the physical properties of the incubator by collecting more trial data. They believe that in the near future, foldable PLA foam incubators will receive more attention and applications from enterprises of many industries. They are keen to provide cold chain transportation companies and suppliers of fresh products with this eco-friendly, low-carbon, economic incubator solution, to make this industry more sustainable. Http://www.bio-plus.cn Figure 1: Manufacturing process of foldable incubators with PLA foam sheet Extrusion of PLA foam sheet Lamination of multilayer Folding and printing of board Making an incubator 24 bioplastics MAGAZINE [01/21] Vol. 16
COMPEO Automotive Figure 2: Comparison of cold insulation effect between PLA foam incubator and traditional EPS incubator (adding ice bags with the same quantity in the incubators) Comparison of cold insulation test temperature (°C) 35 30 25 20 15 10 5 0 0h 1h 2h 3h 4h 5h 6h 7h 8h 9h 10h 11h 12h Leading compounding technology for heat- and shear-sensitive plastics Temp in PLA foam incubator 27 2 2 3 2 2 2 2 1 2 2 2 2 Temp in EPS incubator 27 2 3 4 4 4 5 5 6 6 6 6 6 Room temp 27 28 28 29 29 28 28 28 28 28 28 28 28 Figure 3: Comparison of hot insulation between PLA foam incubator and traditional EPS incubator (adding bottles with hot water of the same quantity in the incubators) Comparison of cold insulation test 90 80 70 60 50 40 30 20 10 0 temperature (°C) 0h 1h 2h 3h 4h 5h 6h 7h 8h 9h 10h 11h 12h Temp in PLA foam incubator 79 62 52 45 41 38 36 34 32 31 30 29 29 Temp in EPS incubator 79 60 49 42 37 34 32 31 30 28 28 28 28 Room temp 29 29 29 29 29 29 29 29 29 28 28 28 28 Uniquely efficient. Incredibly versatile. Amazingly flexible. With its new COMPEO Kneader series, BUSS continues to offer continuous compounding solutions that set the standard for heat- and shear-sensitive applications, in all industries, including for biopolymers. • Moderate, uniform shear rates • Extremely low temperature profile • Efficient injection of liquid components • Precise temperature control • High filler loadings www.busscorp.com Figure 4: Picture of flat foldable incubator with PLA foam sheet Figure 5: A standing foldable incubator with PLA foam sheet bioplastics MAGAZINE [01/21] Vol. 16 25
