Although the printing ink industry has come a long way in making inks and coatings more environmentally friendly, many misconceptions still exist about how safe they are to use and dispose of. Because many of the ingredients that go into inks are derived from petrochemicals, they are immediately suspect. But while they may be considered hazardous and must be handled in certain ways, they are not necessarily toxic.
Almost all of today's inks have had lead or other heavy metal compounds eliminated from their formulas. They are not considered edible, however, and should not be ingested. Surplus inks should be disposed of in approved landfills or, better yet, used as fuel in cement kilns or similar incinerating programs.
Although the petroleum solvents used in heatset inks have had their aromatic compounds reduced to zero, the Environmental Protection Agency still restricts their emission into the atmosphere, as they contribute to photochemical smog. Consequently, most heatset printers today have control devices on their driers that catalytically incinerate the solvents (commonly know as VOCs, or volatile organic compounds).
The soybean substitute?
Considerable confusion surrounds the use of soybean oil as a substitute for petroleum oil in printing inks. Soybean oils contain no VOCs, are a renewable source, and are grown domestically. However, soybean oil-based inks cannot replace the volatile solvents in hearset inks, since soybean oil does not evaporate. They can replace the linseed oil that is already in these inks as a plasticizer, but that is merely replacing one vegetable oil for another. Soybean oils can also replace the quickset solvent in sheetfed inks, but slow the setting time since they don't penetrate the paper as rapidly.
It is in the area of non-heatset web inks (those that are used for newspapers and inserts) that soybean oil finds its most useful application. Because its physical characteristics are very similar to the petroleum oil used in non-heatset inks, the transition has been fairly easy to make.
In terms of de-inking, soybean oil-based inks are no better and no worse than conventional inks. There is no disposal advantage with soybased inks since they still contain pigments, petroleum waxes and resins.
Solvent recovery systems
Gravure inks, which are quite volatile, also contain petroleum …