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FLEXO Magazine : November 2008
the largest cost factor of plate production (see Figure 2). For this study, an identical plate sales price was assumed for both alter- native 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 consump- tion 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 cus- tomer in Europe. Then we defined a user benefit, which was 10 square meters (approx. 100 sq. ft.) per processing round. This is important be- cause it relates to real life usage. Normally, the dryer is the bottle- neck 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 de- velopment (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 consid- er the energy used for distillation. Leftover thermal material can- not 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 custom- ers sacrifice some solvent so that it will flush out of the distilla- tion 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 en- vironmental impact are the consumption of natural resources, the energy consumption of the whole production process and the impact of each plate pro- duction 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, pack- aging, imaging, exposure, thermal development, wash- out and drying, etc. Initially, the amount of greenhouse gas emissions is higher for the solvent process. However, solvent recovery has a positive ef- fect here as with costs, so the carbon footprint for the overall process of solvent- 6 6 F LEXO NOVEMB E R 20 0 8 www. f l e x o g r a p h y. o r g