TEXTILES.ORG
Eco-friendly inks protect your health and the environment.
By Michael Labella
When it comes to digital printing and the environment, things can get “messy.” Consumers demand vibrant colors that will withstand washing, light exposure and crocking. Manufacturers respond with the development of inks and color fixation techniques that deliver the desired results. Unfortunately, brilliant colors and wash fastness are often achieved with great damage to the environment and the health of those who use them.
There is a misconception that ink is harmless, however ink can be hazardous and can cause headaches, skin rashes and damage to the nervous system. Many chemicals used in inks can be dangerous to the environment, the ozone layer and ground water.
Consumers are becoming more aware of the effects that everyday chemicals have on the environment and their own health. Governments are responding by tightening regulations and forcing industries to adopt sustainable and eco-friendly practices. It’s no wonder that more and more printers find themselves reviewing their processes and looking for ways to be better stewards of the environment and their health, while maintaining the quality and performance that their customers demand.
There are different shades of “green,” from environmentally friendly, with reduced pollution levels compared to the standard product, to environmentally safe or neutral, with no negative effect on the environment. True environmentally sound programs should look at the whole production cycle of a printed product and the various components that go into it. So, in addition to the chemistry of the inks, we should look at the power consumption of the equipment, as well as the waste and byproducts generated by the use of those products.
From the chemicals used in the ink base to the colorants and the equipment or processes needed to dry, cure or dispose of them, there are many factors to consider when choosing the right ink. The chemistry of the ink is certainly important, as many inks, such as solvent-based inks, emit high levels of volatile organic compounds (VOCs). Most UV inks and new latex-based inks don’t emit any VOCs, but they require a lot of power to cure them and optimize their properties.
The chemistry of the coatings applied on textiles for direct printing is another area often overlooked but connected to the type of inks used, as they can contain substances such as formaldehyde.
To determine the most eco-friendly ink, ask yourself and your suppliers these four basic questions:
- How many and what kind of VOCs are emitted by the ink?
- Are there any heavy metals in the formulation?
- How much energy will I need to cure the ink or scrub the air of the pollutants emitted by the process?
- Can you put it in writing?
The answers to these questions will assist you in determining an ink’s level of “eco-friendliness” compared to other inks.
VOCs
According to Environmental Protection Agency (EPA), a VOC “is any organic compound that participates in atmospheric photochemical reactions except those designated by EPA as having negligible photochemical reactivity. Many VOCs are found in emissions from burning coal, oil and gasoline, and in solvent based inks. VOCs are of special concern because they photo-chemically react (in sunlight) to cause ozone or smog.”
It is important to note that there are some VOCs that are not considered dangerous, so when asking your supplier for VOC emission statements one should not expect a blanket zero-percent VOC emission declaration. There are a number of VOCs that the EPA excludes from their “bad” list.
Solvents are a common source of VOC emissions and they are commonly used to manufacture solvent-based inks, which are widely used to print on vinyl and other substrates, such as specially pre-treated fabrics in the sign industry. Oil-based inks also emit VOCs, while water-based inks, such as aqueous dye-sublimation, acid dye, reactive-dye and new latex inks have no harmful VOC emissions.
Dye sublimation inks are available in a solvent formulation and are typically used in grand-format printers. The speed of those printers requires the ink to dry quickly, and the solvent-based formula facilitates that process. However the “green” qualities typical of water-based dye-sublimation inks are lost due to the VOC-emitting solvents in the ink base.
When using solvent-based inks, an air scrubber or filter should always be used, and any waste ink, whether it is used or in the bottle, needs to be properly disposed of through a professional service because the VOCs in the inks can infiltrate and pollute water supplies if dumped in landfills.
In recent years, ink manufacturers have introduced mild-solvent or eco-solvent inks with reduced VOC emissions. Also promising is the introduction of bio-solvent inks made with solvents that are derived from renewable resources. Mutoh’s Mubio ink and AT Ink’s BIO ink are made using a solvent called ethyl lactate, a biodegradable compound that is produced from corn and soy. Because ethyl lactate is easily biodegradable and emits non consequential amounts of VOCs, inks made with it are considered to be the “greenest” solvent-based inks available. In certain cases, printers will have to decide between quality and eco-friendliness because eco-solvent and bio-solvent inks aren’t usually as durable as true solvent inks.
Heavy metals
Heavy metals that can be found in inks include lead, cadmium, chromium, mercury, antimony, barium, selenium, silver, nickel, copper and arsenic. Interestingly, small amounts of some of these metals are necessary for good health, but in larger amounts they can be poisonous. Many local and state governments strictly regulate the use of heavy metals in a variety of products and industries and, more recently, in printed products. Since metal content is not usually listed on the label or MSDS, a safe choice is to purchase products manufactured by a member of The Ecological and Toxicological Association of Dyes and Organic Pigments Manufacturers (ETAD). ETAD members adhere to a strict code of ethics, suggesting that inks will be free of known carcinogenic dyes and heavy metals.
The easy choice for printers is to choose a supplier that is an ETAD member, as they voluntarily comply with regulations. Customers can also ask suppliers to provide compliance letters for certain standards.
Energy
Most of the inks used for inkjet textile printing are water based. Typical water-based inks used in textile printing include acid dye, reactive dye, pigment and most dispersed inks, including dye sublimation. Aqueous inks are considered to be the most environmentally friendly of all inks used for textile printing because they don’t emit VOCs—they do however require varying amounts of energy, as they are usually post treated for optimal color and wash-fastness properties.
Dye sublimation and dispersed dyes are used to print on polyester and require heat (usually 400 degrees Fahrenheit for about 30 seconds). So while the ink is certainly green, consider the power consumption of the heat press used because different models can require significantly different amounts of power.
The paper used in dye-sublimation transfer can be recycled as a grade “A” paper (the equivalent of unprinted paper), and using recycled polyester (usually derived from used plastic bottles) will reduce impact on the environment.
Acid and reactive-dye inks are aqueous and require curing in an oven or steamer for proper color fixation. Washing and drying are a necessary part of the finishing process, so power and water efficiency should be examined. Because these inks need either an acid or alkali environment for proper color fixation, local codes should be checked to ensure that the waste water gets properly treated.
Textile pigment inks are a clean option, possibly the cleanest of the various textile inks available. Unfortunately they offer the worst performance when it comes to color reproduction and wash fastness, often making them unusable for commercial purposes. Pigmented-based textile inks required extended heat curing (usually three to six minutes) at about 300 F. This type of ink is commonly used on direct-to-garment printers where a pre-treatment spray is often applied in order to improve the quality of the image and color saturation. Some of the pre-treatments contain formaldehyde.
UV inks are gaining popularity in the sign industry for their versatility and the absence of VOC emissions. However, the amount of energy needed for the UV-curing process is usually considerable. UV inks can be used to print on some textiles, however the results are generally poor and the hand of the fabric is greatly compromised.
Latex inks, recently introduced by HP, are gaining popularity in the sign industry where fabric is used for banners, pole flags and trade show graphics. Very little is known about those inks, as they have just been introduced, but HP is presenting them as a “green” alternative to solvent-based inks. Latex inks are water-based and emit low levels of VOCs. They do, however, require a lot of heat and power for proper curing and adhesion to the substrate.
Put it in writing
nvironmental stewardship is fashionable. Marketers have taken notice, so the words “green” and “eco-friendly” are appearing on labels and promotional materials of virtually every product sold for inkjet printing. Many manufacturers claim to have a green product, but don’t explain what about the product is really green. Before you buy into a green product, you might want to ask the manufacturer exactly what it means. If the product claims no VOCs or no heavy metal content, ask the manufacturer to confirm that in writing, especially if it claims to comply with specific laws.
In many cases, the specific ink to use in a particular application is dictated by the type of textiles needed to print, giving us little choice but to use a not-so-eco-friendly product. In those cases, using the proper equipment to process the materials and disposing of the harmful byproducts will go a long way to reduce the negative impact on the environment.