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Flexo Sustainable : Fall 2008
the largest cost factor of plate production (see Figure 2). For this study, an identical plate sales price was assumed for both alternative processes. In addition, solvents and correspondingly web material were also important factors. If you compare the solvent process to the thermal process, ini- of equipment to determine the amount of energy consumption for drying, exposing and laser ablation. Total numbers were drawn based on an annual plate usage of 10,000 square meters (approx. 100,000 sq. ft.), which would be a medium sized customer in Europe. Then we defined a user benefit, which was 10 square meters (approx. 100 sq. ft.) per processing round. This is important because it relates to real life usage. Normally, the dryer is the bottleneck in the process, and so it is usually filled. If you consider the whole process for a single plate in a solvent processor and one plate in the dryer, that is not realistic. Difference in costs Costs taken into account include transportation, packaging, cutting, plate disposal, mask ablation, UV exposure, solvent development (for solvent plates), solvent redistillation (for solvent plates), drying, plate price, solvent price (for solvent plates), and the polyamide (PA) web price. The printing plate itself represents tially you have higher costs and energy consumption. But, you get a bonus if you recover the solvent. It does not have to be remade from natural gas and other raw materials, even when you consider the energy used for distillation. Leftover thermal material cannot be recycled; it must be disposed of. As is common in most industrialized nations the remaining un-reclaimed solvent and sludge must be incinerated. This offers another bonus on energy. The study found a recycling rate of 87.5 percent of the solvent. This number is the average, based on feedback from customers, who say they are recycling between 80 and 90 percent of their solvent. Normally, it is possible to recover more than 90 percent, but that can leave sludge in the distillation unit, and so customers sacrifice some solvent so that it will flush out of the distillation unit. This high percentage recovered through redistillation reduces significantly the cost of solvent-based plate production. The remaining investigated cost-factors are either comparable, or so small that their impact on the overall result hardly needs considering. The bottom line is that the proven solvent process records a cost benefit of more than 10 percent. environmental impacts The key factors of an Eco-Efficiency-Analysis to assess the environmental impact are the consumption of natural resources, the energy consumption of the whole production process and the impact of each plate production step on the global warming e.g. due to the CO2 emissions—also known as the “carbon footprint.” For this, numerous points are to be taken into consideration, such as plate manufacture, web manufacture, solvent production, transport, packaging, imaging, exposure, thermal development, washout and drying, etc. Initially, the amount of greenhouse gas emissions is higher for the solvent process. However, solvent recovery has a positive effect here as with costs, so the carbon footprint for the overall process of solvent- 14 Sustainable FLEXO FALL 2008 www. f le xomag.com
End of Year 2008