Applied properties and life cycle assessment of flexible packaging lamination processes: a comparative study

Environmental pollution is a growing problem in developing countries, including China. The packaging-printing industry is considered as one of the main contributors to air pollution in China. Film lamination represents a critical proportion of flexible packaging products. At present, traditional lamination technologies, e.g., dry lamination, consume considerable resources and generate massive pollution. Correspondingly, novel solventless lamination could effectively replace conventional lamination processes and reduce air pollution, particularly the production of volatile organic compounds (VOCs). To promote cleaner packaging and printing production in China, we applied life cycle assessment (LCA) to compare solventless and dry film lamination processes in retort pouch packaging production and further validate the environmental advantages of the solventless approach. Our research model considered the entire LCA process with an emphasis on film composite processing. E-footprint software and databases were used to assess environmental impacts based on the ISO 14040 standards. In addition, the laminated films were further assessed for peel strength based on the GB standards. Six environmental indicators, including global warming potential (GWP), photochemical oxidant formation potential (POFP), primary energy demand (PED), water use (WU), acidification potential (AP), and respiratory inorganics (RI) were selected, with a particular focus on the first two indices. The LCA results showed that the environment impact of solventless lamination was markedly smaller than that of traditional dry lamination, with critical differences reflected in power consumption and adhesive type. Compared with dry lamination, solventless lamination reduced electrical energy consumption and CO2 emissions by 74.1% and 86.37%, respectively, and the unique adhesive reducing VOC emissions by more than 94.5%. Further estimation results confirmed the above findings, indicating that solventless production can reduce VOC and pollutant emissions from sources and thus promote cleaner production. In short, solventless lamination is an effective method, both in terms of performance and environmental friendliness.