Blow Moulding
Blow Moulding Bio-packaging of liquid dairy products Environmental, economic, safety and regulatory Definition of requirements and selection of materials Development of bottle packages for liquid dairy products Figure 1: BIOBOTTLE work scheme Reactive extrusion Validation at pilot plant scale Industrial scale up and product validation Figure 2: Negative search for pathogenic bacteria Development of pouches, lids and caps The aim of the BIOBOTTLE project is to develop new biodegradable materials suitable to obtain plastic bottles and pouches for dairy products; probiotics, fresh milk and shakes. These packages do not need to be separated of the rest of the organic waste at the end of their short shelf-life. The new packages keep the shelf-life of selected dairy products in comparison with traditional packages as well as fulfill different characteristics based on functional, microbiological, legal requirements for food contact applications in each case study. In addition, the new materials are suitable to be processed by traditional plastic processing methods, such as blown film coextrusion, extrusion blow moulding and injection moulding to obtain pouches, bottles and caps, respectively. The materials are completely biodegradable under controlled composting conditions (ISO 14885-1:2005) and are harmless after biodegradation according to the Compostability Standard, EN 13432. Market Data The worldwide output of plastics increases each year, but the management of plastic disposal has no satisfactory environmentally friendly solution at the moment because landfilling is still the first option in many countries [1]. As a consequence of this problem, there has been an increased interest in using alternative materials such as biodegradable bioplastics. Nowadays, the European countries are the biggest consumer of milk products in the world, with an average of 219 kg per year (FAO, 2011). Therefore, the use of biomaterials to package dairy products is especially interesting for both dairy and plastic industries as well as for the endusers since the packages can be managed in composting conditions with the rest of the organic wastes. Requirements of bio-packages The requirements that the packages for dairy products must fulfil are shown in table 1. According to these requirements, one of the main difficulties overcame by the researches of the project, was the thermal limitations of the commercial biodegradable materials, which showed thermal resistances around 65 ºC. The compounding process has been carried out using reactive extrusion technology, which lead to the development of different bio-compounds suitable to obtain the packages used in thermal treatments such as the sterilization or pasteurization processes that reach temperatures up to 90 – 95 ºC. The bio-compounds are different PLA based biopolyesters with renewable content between 20 and 45 %. Figure 1 shows the development work in the BIOBOTTLE project. 12 bioplastics MAGAZINE [04/16] Vol. 11
Blow Moulding By: Pilar Diego, Chelo Escrig Extrusion Department AIMPLAS (Plastics Technology Center) Valencia, Spain Partners Seven companies and technological centers have worked with AIMPLAS, who has coordinated this project; VLB (Germany), OWS (Belgium), CNR (Italy), VIZELPAS, ESPAÇOPLAS (Portugal) and ALMUPLAS, ALJUAN (Spain). About AIMPLAS AIMPLAS is a Plastics Technology Center located in Valencia, Spain. It is a non-profit research association which has the objective of acting as a technological partner with companies in all sectors related to plastics, customizing integral and personalized solutions through the coordination of R&D&I projects and technological services. Mode of operation The 2-year project was finished in May 2016. The first period of the project was mainly focused on the studies at lab and pilot plant scale while the second period mostly concentrated on the industrial scale-up, product validation and environmental and economic studies, i. e.: • Definition of requirements, material selection based on the biodegradable materials and additives and study of chemical modifications • Evaluation of bio-compounds’ processability at pilot plant level considering the different manufacturing processes: Blown film extrusion and form-sealing packaging machine to obtain pouches, extrusion blow moulding for bottles and injection moulding for caps. • The scaling-up industrial processes according to the optimized parameters at pilot plant level and the optimization state to achieve the desired output (see figures) • Full characterization and validation of the final industrial products to be used in the dairy applications defined Table 1: Requirements of the packages for dairy products Package Flexible pouches Small bottle Big bottles and caps Type of contained product Fresh milk Probiotic yogurt products Fresh milk and shakes Shelf-life 4 – 7 days at < 8 °C 2 – 3 weeks at < 8 °C 2 – 3 weeks at < 8 °C Thermal treatment Technology Pasteurization 72 – 75 °C, 15 – 40 s Blown film coextrusion Pasteurization 72 – 75 °C, 15 – 40 s Extrusion blow moulding Sterilization (bottle) 90 – 95 °C, 4 – 20 s Extrusion blow moulding and injection moulding Package structure Multilayer (3 layers) Monolayer Monolayer Additional requirements Withstand horizontal form sealing machine Lid sealing Lid sealing and caps Barrier properties Not applicable Not applicable Not applicable Table 2: Thermal and mechanical properties in pouches (MD=Machine Direction, TD= Transverse Direction) Standard Formulation Reference LDPE Bio 03-04 EN ISO 527-2: 2012 EN ISO 14477: 2004 Direction MD TD MD TD Stress at yield (MPa) 1.7 ± 0.1 1.4 ± 0.2 1.8 ± 0.2 1.1 ± 0.1 Elongation at yield (%) 16 ± 1 9 ± 0.9 32 ± 9 12 ± 1 Stress at break (MPa) 2.3 ± 0.2 2.1 ± 0.4 3.8 ± 1 2.6 ± 0.1 Elongation at break (%) 710 ± 120 1200 ± 150 620 ± 89 660 ± 35 Maximum Stress (MPa) 2.79 ± 0.16 4.67 ± 0.14 2.79 ± 0.16 4.67 ± 0.14 Penetration (mm) 1.6 ± 0.1 1.80 ± 0.04 1.6 ± 0.1 1.80 ± 0.04 Energy (mJ) 2.54 ± 0.17 4.72 ± 0.25 2.54 ± 0.17 4.72 ± 0.25 Thickness (microns) 120 100 EN ISO 306 Vicat Temperature (ºC) 100 – 115 92 – 95 bioplastics MAGAZINE [04/16] Vol. 11 13
