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FLEXO Magazine : End of Year 2008
Sustainable FLEXO YEAR END 2008 www.flexomag.com The use of bio-derived renewable materials in place of petro- leum sourced materials is a measureable property and is generally believed to improve ink's overall environmental profile. Examples include: Oils from plants and trees such as flaxseed (linseed), chi- • nawood (tung), soy, corn, safflower, etc. (also referred to as vegetable oils) Materials based on animal sources such as fish oil, tallow, • some colorants Materials based on insects such as shellac, some specialized • colorants Resins based on plant or tree sources such as wood rosin, tall • oil rosin, gum rosin, nitrocellulose Plant derived solvents such as ethyl lactate, grain derived • alcohols Fatty acid esters such as tall oil fatty acid methyl ester • Naturally renewed resources such as water. • It is important to note that gauging the full environmental im- pact resulting from the use of these materials is highly complex and somewhat subjective, requiring certain assumptions and ar- bitrary determinations as to how far back one goes into the over- all process. Minimally, this would include a comprehensive evalua- tion of the manufactur- ing process and refine- ment for use of the bio-derived renewable materials. The initial stages include aspects such as planting, fertil- izing and harvesting, followed by the refining stage that includes air emissions, energy us- age, water discharges, by-products and gen- erated wastes. For example, plant derived materials start from the time the seeds are planted in the soil to delivery of the product to the ink manufacturer. There have been very few lifecycle studies conducted on materi- als used by the ink industry due to the complexities, cost and time involved. Battelle conducted a lifecycle study in 1998 of soy-based sheetfed ink, but did not draw any clear cut final conclusions re- garding the environmental impact of soy versus petroleum oils. VOC CONTENT Reducing product VOC content is a generally accepted tech- nique for reducing environmental impact because lower VOC containing products emit fewer emissions during manufacture and use. Over the last two decades, ink companies have made a significant effort and investment in developing and reformulat- ing ink systems that have lower VOCs than inks sold previously for similar applications while continuing to meet customer requirements. The percentage of VOC in an ink is highly dependent on the type of ink, with some inks requiring a higher level of VOC in or- der to function and dry during the printing process. Flexographic solvent inks contain a higher concentration of VOCs than either water-based or energy curing inks (see Table 1). It is important to note that many printers using solvent-based inks employ sophis- ticated "capture and control" mechanisms to minimize air emis- sions during the printing process. HAZARDOUS AIR POLLUTANT CONTENT Hazardous air pollutants (HAPs) are those materials that are known or suspected to cause cancer or have serious health effects, such as reproductive effects or birth defects, or adverse environ- mental effects. The EPA has identified 188 specific chemicals as HAPs which are listed in Section 112 of the Clean Air Act. HAPs can also be volatile organic compounds (VOCs) depending on the physical/chemical prop- erties of a particular material. Lowering or elimi- nating the amount of HAPs contained in printing inks is another way of reducing the overall environmental impact. Among other requirements, The Printing and Publishing MACT standard speci- fies a compliant ink as one that contains no more than 0.04 weight fraction organic HAP. Some gravure and flex- ographic inks are based on high levels of solvents classified as HAPs and rely on recapture techniques to minimize emissions of such products. HEAVY METALS Essentially, all inks sold in the U.S. today are manufactured without the use of compounds based on toxic heavy metals (i.e. lead, arsenic, selenium, mercury, cadmium and hexavalent chromium). Federal health and environmental regulations were enacted in the United States beginning in the 1970s that made the usage of the known highly toxic metals as printing ink formu- lation components an unattractive option and ultimately resulted Due to the small quantity of ink in relation to the much larger amount of substrate, ink has a minimal or negligible impact on biodegradability when printed materials go to landfills.