For ink formulators, one possibility was to create water-based systems, which would accomplish the goal of reducing VOCs. The water-based inks have improved over time, and today, these water-based systems have had a major impact in a number of areas, particularly in flexo.
However, there is still room to grow. Water-based inks’ future growth depends on what the EPA does, and whether printers are looking to change over to water once their incineration and capture and control equipment depreciates. Meanwhile, formulators are looking to improve the properties of water-based inks to reach into other segments of the market.
Water-based inks have made major inroads in the flexo packaging market. According to the National Association of Printing Ink Manufacturers’ (NAPIM) 1999 State of the Industry report, water-based flexo inks account for 37 percent of the packaging market.
“Flexo has been the strongest market for water-based inks in the corrugated, folding carton, a lot of the paper market, multi-wall bags and low to medium film market, and it is continuing to emerge in the higher-end markets,” said Chris Patterson, director of product development, packaging inks, for Flint Ink North America. “The flexo market grew up with water-based inks. As certain elements of flexo improved, so did water-based inks.”
“There are certain market segments that are almost exclusively water-based,” said Gerald McLain, marketing manager, packaging inks, for Sun Chemical Corporation. “For example, it is the predominant process in narrow web label. Other areas where water flexo is the primary process include folding cartons, plastic grocery sacks and department store bags, multi-wall bags, corrugated, and envelope printing.
“There has been significant growth in the usage of water-based ink in what I call ‘the easy market’: paper products, paper bags, corrugated products, both pre-printed ad post-printed, multi-wall bags, and polyethylene products such as grocery sacks and polyethylene parts bags, and milk cartons,” said Darryl Sagraves, technical market manager for Sun Chemical Corporation. “Water-based ink have achieved a dominant position in these areas.”
There is opportunity for growth in film laminating. “Water-based inks are used for both paper and film, with film growing at a faster rate,” Mr. McLain said. “In film laminating, water-based inks are making gains, although many of the laminating printers have invested in incineration equipment. As these incinerators may need to be replaced, they may have to revisit these decisions. Water-based inks are very well suited for process printing for film, where the versatility and printability of the ink is very important.”
In the future, we foresee real growth in the use of water-based inks for laminating purposes due to the protective nature of the laminating structures,” said Mr. Sagraves. “The inks, which are sandwiched between the film layers, rely on the films to impart properties of gloss, scuffing resistance, and chemical and product resistances. Laminating bonds of water-based product are equaling or exceeding their solvent-based counterparts.”
While there has been some entry into the gravure market, water-based inks still have made little headway. NAPIM reported that in 1999, water-based gravure inks held 5 percent of the packaging market. Still, water-based inks are making gains in traditional gravure areas such as gift wrap and folding carton.
“Water-based inks have been used in gravure for applications such as beverage and detergent cartons and gift wrap, but it really hasn’t caught on,” Mr. Patterson noted.
“Water-based inks have been explored for many applications for flexographic and roto-gravure printing,” said Kent Shah, vice president and chief technology officer at Color Converting Industries. “Through decades of work, it has successfully transitioned many areas where solvent-based inks were used. However, there is limited activities in the areas which have been difficult to replace solvent-based inks without sacrifice, such as non-porous substrates and roto-gravure printing. Lately, water-based inks have made some inroads into folding cartons where solvent gravure and offset dominated the market.”
Mr. McLain said that there is much room for growth for water-based inks. “Aside from certain niche markets, there are few printing applications that can’t be done with water-based inks that are being done with solvent-based inks,” Mr. McLain said.
Over time, water-based ink manufacturers have worked to improve their products, and have turned previous disadvantages into positives.
“The ink systems have matured and grown, and there’s less of a difference,” Mr. Patterson said. “Over the last 10 or 15 years, the improvements have been more noticeable.”
“Early on, the advantages list was short and the drawback list long,” said Grant Wishart, director of corporate services at Graphic Sciences, Inc. “The advantage list cited mainly environmental and safety issues. The drawbacks were typically difficulty of use, maintenance of ink, and limited substrates. The scales are now tipping toward the advantages side. We have overcome most of the issues, and are working on the few drawbacks that remain. We are fighting mainly notions now. Proving these notions wrong has been the focus of our efforts.”
“There are still skeptics who remember the introduction of water-based inks in film many years ago, before corona treatment and surface energy were understood as well,” Mr. McLain said. ‘Film and inks have come a long way.”
Aside from environmental issues, water-based inks have other advantages, such as stability and lower flammability ratings.
“Water-based inks tend to be more viscosity stable on press due to the slower evaporating nature of water,” Mr. Sagraves said. “Water-based inks have lower VOCs and indeed can be formulated with zero, or near zero, percent VOCs on many paper products. Newer generations of water-based products are easier to clean up than their solvent counterparts; rinsing with a mixture of soap (or a mildly alkaline cleaner) and water will usually do a thorough job of cleaning water-based inks from press parts. Also, water-based inks have lower flammability ratings and many are non-red label products with such high flammability points that insurance restrictions are eased.”
Drying times remain the most serious disadvantage to water-based inks, as print speeds are adversely affected.
“Print speeds are limited by drying speeds,” Mr. Patterson said. “You have got difficulties with the laws of physics – water dries more slowly in comparison to regular solvent-based inks.”
“They contain water, and water is not quick to evaporate from the printed film, thus slowing print speeds unless the press is equipped with adequate dryers,” Mr. Sagraves said.
“Among the other reasons for slow progress for changing solvent to water, the most critical one is its drying speed,” said Mr. Shah. “The ink film thickness of roto-gravure is much higher than flexo, creating demand on ink drying speed. This resulted in unacceptable productivity, especially in publication gravure where print speed can top to 2500-3000FPM.”
There are other drawbacks. “Water-based inks are soluble in alkaline solutions and thus are restricted in uses around highly alkaline environments,” Mr. Sagraves said. “Water-based inks don’t have the resistance to frozen food applications as their solvent counterparts, although this is narrowing rapidly. Water-based inks do not wet and print smoothly on many difficult substrates due to the high surface energy of the water component.”
Improvements in ease of use and performance have been critical in increasing water-based inks’ market share.
“Our primary customer-driven innovations seem to embrace the ‘user friendly’ issues lately,” said Mr. Wishart. “As our products become more user friendly, and we tackled more and differing substrates, the flexo market gradually became more receptive to water-based inks. For years the water-based ink industry has been playing catch-up with solvent-based systems that made ‘ease-of-use’ and ‘good crisp printing’ their clear advantages. As the industry watched water-based systems match the quality and reliability of solvent inks, converters’ confidence rose and more jobs were converted to water-based flexo. Today, we are still focused on ease-of-use. This comes from our customers and continues to be the driving force behind our new developments.”
Mr. Wishart said one requirement of customers is for pH stable water-based inks. “We have developed pH stable inks that do not need to be monitored for pH during the print run,” Mr. Wishart said. Resolubility is another important area of research, as the inks cure as amines evaporate and resins revert to solids, even on the print deck. “Recently, due to improvements in the resins used, our inks are more resoluble than ever before,” Mr. Wishart said. “This means the converters can run longer between wash-ups, thus improving output.
“Graphic Sciences will continue to make our products more user friendly,” Mr. Wishart said. “Our inks and coatings will become higher performance and continue to close the gap on the solvent-based high-end performance issues.”
“The quality of water-based inks continues to improve in the difficult areas, performance factors on the polyolefin substrates, in alkaline resistance, and in frozen food applications,” Mr. Sagraves said. “In many areas, gloss, scuffing and printability, it is difficult to differentiate water-based inks from their solvent-based counterparts.”
‘The industry is also starting to see a gradual improvement in product resistance properties of surface and reverse printed aqueous products, specifically in areas of resistance to oils and greases, better resistance to heat applications, and better resistance to frozen food applications,” said Mr. Sagraves.
“Our products must offer resistance properties once printed on the packaging,” Mr. Wishart said, including resistance to water, crinkle and tape testing. “These resistance properties are inherent with most solvent-based systems. The water-based industry must struggle, invent and push the limits of our technology to gain those resistance properties. When our inks cure, they become resistant to these things. The longer they cure, the more resistant they become – to a point. If ink is allowed to cure on press, and it depends on how long the operators wait to clean up, they will undoubtedly encounter clean-up problems. This can lead to many other printing problems down the line.”
Mr. Sagraves said that strong cooperation between ink manufacturers and their suppliers, press makers, film suppliers and other key companies could herald further innovations that would advance water-based inks.
“With a joint industry effort on the part of ink suppliers (better formulation), film suppliers (more water-receptive film surfaces), and press manufacturers (dryers equipped to handle the slow drying nature of water), water-based products may continue to grow in usage and offer the printer a viable choice for his VOC compliance programs,” Mr. Sagraves said.
Ink manufacturers still see the government as the ultimate driver as to whether water-based inks will make a further surge in the market. Currently, there are pressures on the federal, state and local levels that indicate that there will be more environmental issues ahead.
“There’s general pressure to reduce VOC emissions, and the EPA is ever tightening limits on ozone emissions, which ultimately translates into lower and lower allowable VOC emissions,” said George Fuchs, environmental affairs manager for NAPIM. “That may translate into increased usage of water-based inks.”
“More growth will come as there are more demands placed on printers and converters by federal, state and local governments,” Mr. Patterson said. “That’s really the driving force.”
“There is constant pressure on the local municipalities to meet the government’s ever more stringent environmental regulations,” added Mr. Wishart. “The printers are constantly looking for ways to make their solvent-based printing operations meet governmental regulations. Most of these efforts center on processing the emissions from the solvent-based printing operations. Most common is the use of ‘incinerators’ which capture and incinerate the VOCs. Other more ingenious systems use microbes or bacteria that feed on the VOCs.
“Both of these methods rely on the efficient capture and delivery of the VOCs to a system that neutralizes them, be it by incineration or as food for the bacteria,” Mr. Wishart said. “We feel confident that in the end it will make more sense to change the ink to a water-based system. The government seems to have less faith in the elaborate systems developed and will continue to tighten the noose. We are here, and actually quite active in the process of convincing the converters that we can switch them over to water-based inks with less trouble than the rumors have it.”
Ultimately, it would appear that government regulations will indeed tighten. “It depends on the Clean Air Act and how strictly it will be enforced,” Mr. McLain concluded. “Enforcement is only going to go in one direction.”
While water-based ink have gained significant market shares in certain packaging segments, it remains to be seen whether it can reach into other areas. Still, the future of water-based inks depends on both further improvements in formulations and technology, as well as government regulations.
“Lead-based paint and asbestos were all good products at one time,” Mr. Wishart concluded. “They still hold qualities today that we wished their present-day substitutes would have. We have made the decision however, that we could do without those qualities in light of the environmental benefits the new products provide. This, we believe, will be the fate of solvent-based printing. Some applications will always use solvent. It will never go away completely, but it will eventually lose its market share. “