Canadian Printing Ink Manufacturers' Association

WHAT ARE VOC's Volatile Organic Compound (VOC) is any organic compound which, when released into the atmosphere, participates in the atmospheric photochemical reactions. Ground-level ozone is produced when nitrogen oxidises and volatile organic compounds (VOC's) react in the presence of sunlight. This is a major component of urban smog, which, at elevated levels, presents a potential health hazard to people of all ages and possibly damages vegetation and degraes the environment. It is for this reason that government legislation to control VOC emissions is being implemented in the US, Canada, Europe and other parts of the world. Printing inks and coatings used in the commercial graphic printing industry contain VOC's in varying amounts, depending on the type of ink, the drying and printing processes, substrates and end-use application requirements. In printing inks, essentially all weight loss, when the wet ink dries on the printed substrate is VOC's with the exception of water. Changes in printing ink technology and formulations are being driven by the desire to lower the levels of air pollution caused by the Graphic Arts Industry. VOC emissions do arise from things other than ink such as isopropyl alcohol. blanket washes, palte developers etc. The following will briefly summarize the different types and typical concentrations of VOC's in the major ink systems which are in use today and offer printers alternative means of reducing VOC emissions into the atmosphere. The Sheetfed Offset Inks for Sheetfed Lithography These types of ink dry by chemical oxidation process. There is typically about 25% to 35% of VOC in the form of petroleum distillates in a conventional sheetfed quickset ink. Most ink manufacturers also produce sheetfed inks which contain 0% to 10% VOC; however these types of ink generally set slower compared to conventional inks depending on the type of substrate used. It is best to consult with the ink manufacturers for recommendations on the proper pressroom operating procedure for low VOC inks. Web Offset Heatset Inks These types of inks are printed using high speed web presses and utilize heat in an oven dryer to evaporate most of the petroleum distillates present in the inks. Typical VOC content in the web heatset inks is 30% to 40% and they are dried by heat evaporating most of their petroleum distillates content. The principle method to reduce/control VOC emissions is to use emission control devices such as a catalytic incinerator. Web Offset Coldset Inks These types of inks are used on high speed web offset presses to print newspapers and advertising flyers. Web coldset inks dry primarily by absorption of the ink oil into the paper fibres. VOC content of the webs coldset ink typically range from less than 5% to maximum of 30%, mainly of petroleum distillates and ink oil. Petroleum distillates have extremely low volatility and most of them are retained in the ink film and substrate after printing. Flexographic Inks These inks are available in both solvent-based and water-based systems. Solvent-based flexo inks primarily contain alcohols and esters as VOC's in concentrations from 50% to 70% at press viscosity. Depending on the substrates, end-use applications and type of press, a printer can control VOC emissions in his facility by use of a solvent recovery system, incinerator or water-based flexographic ink. Water-based flexographic inks with extremely low VOC's have successfully replaced traditional solvent-based inks on many substrates and end-use applications. Examples of these are: paper, foils & films for labels, plastic shopping bags, wallcoverings, polycoated beverage containers and general folding cartons. Consult with the ink manufacturers for their recommendations on the type of water-based inks best suited to meet quality and end-use requirements. Gravure Inks Solvent-based gravure inks for packaging cartons and flexible films are basically similar to flexographic inks in their content and composition. Again, water-based gravure inks have successfully replaced high VOC containing solvent-based gravure inks in many general folding carton applications. Water-based inks are being used wherever possible on flexible films and publication printing in the US to reduce VOC emission. U.V./E.B Inks and Coatings These types of inks dry through the use of energy to affect a rapid cure. These technogically sophisticated printing inks contain components which are essentially non-volatile and therefore emit minimal VOC's during printing and drying. Issued: January, 1998

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