The truth about inks - printing-ink industry - Industry Overview

Folio: The Magazine for Magazine Management, Annual, 1994 by Terry Scarlett

The ink industry has come a long way toward eco-responsibility.

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 knows as VOCs, or volatile organic compounds).

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 heatset 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 soy-based inks since they still contain pigments, petroleum waxes and resins.

Gravure inks, which are quite volatile, also contain petroleum solvent. Publication gravure inks traditionally used solvents known as lactol spirits or VM&P naptha. More recently, toluene-based inks have found greater acceptance. It is true that all these solvents are considered unsafe to be emitted into the atmosphere. However, the industry has developed solvent-recovery systems that re-distill the evaporated solvents into holding tanks so that they can be reused in inks. Toluene is a very efficient solvent for this purpose -- hence its popularity. So, two issues have been addressed: The environment is protected, and the product is recycled.

Water-based inks have been tried as a means of eliminating petroleum solvent altogether, but with limited success. They require more heat to dry, they do not print as well or have as much gloss, and the water tends to distort the paper, causing waviness in the printed product.

High-gloss clear coatings, frequently used on the covers of books and magazines, in the past used various types of volatile petroleum solvents. Shellac coatings contained alcohol, while catalytic coatings contained acetates, ketones or xylene. Most of these have been replaced by ultraviolet (UV) cured coatings. UV-cured coatings consist of a liquid acrylic monomer with certain additives that, when subjected to high-intensity UV light, convert to a solid. Since no solvents are emitted during the process either into the pressroom or the atmosphere, it is a pollution-free process.

De-inking is a concern with UV inks and coatings, as they do not break down easily with conventional techniques. However, with the increased use of the flotation process for de-inking, they can be handled.

Water-based coatings, which are basically an acrylic emulsion, are a good alternative. They do require some heat to dry and to date do not have quite the gloss of UV coatings, but they will de-ink better and so offer a useful alternative.

It can be seen that the ink industry has come a long way producing environmentally acceptable products. They should still be used and disposed of in the correct manner, but if the environmental guidelines are followed, they should present few problems to the printer or publisher.

Terry Scarlett, president of Burntwood Industries, wrote What the Printer Should Know about Inks.