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A PIE Blog reader recently asked about using recyclable UV inks on recyclable media such as polypropylene. Since this is somewhat outside my knowledge base, I went to school on the subject online, and here is what I found, along with my own personal experience with such inks and papers.
Qualities of Inks (and of UV Inks in Particular)
Let’s start with what UV ink is. Many contemporary ink formulations can be cured using UV light. The alternative “drying options” using more traditional inks are oxidation (evaporation of the vehicle, the liquid part of the ink, into the surrounding atmosphere) and absorption (in which the ink vehicle is taken into the fibers of the paper substrate).
In these cases the pigment is left on the surface of the paper (or other custom printing substrate) once the vehicle is gone.
Unfortunately, some of the gases given off as the vehicle disperses are harmful to the environment. Because of this, in recent decades there has been a concerted effort to minimize the VOCs (volatile organic compounds) given off during the drying of ink.
To get back to the reader’s question, when specially formulated UV ink is used on a commercial printing press, exposure to UV light “cures” the ink (similar to drying). The ink becomes a solid. Moreover, it sits up on the surface of the coated or uncoated paper or other substrate.
This yields three benefits:
- Since UV ink cures instantly when exposed to UV light (in contrast to the other drying methods noted above), and since it therefore sits up on the surface of the paper, the colors maintain their intensity or saturation. Less ink is needed to create brilliant coloration because it doesn’t seep deeply into the paper fibers.
- UV inks can be used not only on coated and uncoated paper but also on completely non-porous surfaces like plastic (to reference the PIE Blog reader’s question about polyprophylene substrates) and even glass and wood.
- This makes UV inks ideal for use on banners (i.e., jobs printed on large-format inkjet equipment, as well as jobs printed on offset lithographic commercial printing presses). Moreover, since UV inks are bright, vibrant, have great adhesion properties, and are stable, flexible, chip resistant, light- and weather-fast, fade-resistant, and low-migration (i.e., good for food packaging since they don’t travel from the substrate to the contents of a food package), they are an increasingly viable choice for a huge range of both flexible and rigid printed products.
But Are They Environmentally Friendly?
In my research, I learned that UV inks have the following environmental benefits:
- Those UV inks that are specifically LED UV are cured with light emitting diodes (LED) rather than mercury vapor lights, as was done in the past.
- These LED UV lights consume far less energy, and generate far less heat, than mercury vapor lamps. They also require lower voltage and have a longer life.
- This means printers don’t need a high-powered cooling unit. The process also emits no infrared radiation, heavy metals, or ozone.
- Because of the reduced energy footprint (lower energy requirements and lower heat emission), LED UV inks are great for heat-sensitive substrates (i.e., certain flexible plastics, for instance).
In addition, UV inks and UV curable paper coatings are recyclable. According to my research, UV printed papers can be deinked (using cleaning, flotation, and dispersion processes to separate the ink from the paper), and then the waste paper can be repulped or reincorporated into the paper mill’s standard “furnish” (their liquid paper blend from which new, dry, fully formed paper can be created).
One thing to consider, however, is that recycled paper is usually of a lower quality than virgin paper. More specifically, the paper fibers are shorter after being made into new paper, and the ink particles may not be 100 percent removable. (Also, the paper won’t be as bright, since brightness is usually achieved through bleaching.)
But this doesn’t have to be a problem. Why? Because repulped paper is usually turned into lower quality board grades (as opposed to bright-white, #1 uncoated commercial printing sheets). Or this paper can be used for tissue, paper towels, toilet paper, or any number of other paper products. Moreover, much of the paper that has been recycled does not include a full 100 percent content of post-consumer waste.
Another thing to keep in mind is that a lot of paper in use is still virgin paper. It’s just that having the option to cut virgin wood for paper or to recycle and then extend the life of the paper fibers through cleaning and repulping makes for a far more thorough and sustainable use of forest resources (even if the trees are being constantly replanted).
Recycling paper in this way also reduces waste being diverted to the landfill.
Ensuring Sustainability
You might want to research the following organizations, which are active in keeping track of the actual sustainability of the process of turning trees into commercial printing paper. These two organizations are the Forest Stewardship Council (FSC) and Sustainable Forest Initiative (SFI). You may see these acronyms on printer estimates or as logos on boxes of custom printing paper.
These organizations track and certify the chain of custody (various steps in the process of planting, growing, and harvesting lumber and making paper), ensuring responsible management of forest resources and the incorporation of post-consumer waste (PCW) into the papermaking process.
So look for these certification logos (FSC and SFI) or ask your printers about their compliance with these certifications.
One thing to keep in mind is that the best (or most sustainable) papers are “FSC Certified Recycled.” This wording ensures the genuinely recycled nature of paper products, more so than any other labeling.
How About Polypropylene Printing Substrates?
I once saw a fish tank at a restaurant with a printed paper ad, or menu (I can’t remember), in the water, tied to the rocks at the bottom of the tank. It was intriguing.
Later on, I learned about such synthetic paper as Yupo. I thought back to the paper in the fish tank, and then realized that for printed products used outside in wet weather, those used for menus, and those used for labels, plastic-based paper was ideal. (Keep in mind that two of the other alternatives are wood-fiber-based paper and cotton-based paper such as stationery bond.)
When you add to these more traditional paper options the newer synthetic stocks (which presumably are not porous) and the particular curability of UV inks (plus their superior adhesion qualities even to non-porous substrates), you have an ideal match.
That said, when all is said and done you still have plastic to recycle. And given the PIE Blog reader’s question about printing UV inks on polypropylene substrates, I did some more research.
This is what I found:
- Polypropylene is rugged and resistant to solvents. Therefore it is useful for durable printed products (such as printed plastic bottles).
- Plastic can now be purified with intense heat at a molecular level to produce clear, odorless, nontoxic plastic pellets from which 100 percent recycled plastic can be made.
- In spite of it’s huge popularity, polypropylene is also one of the least recycled materials.
- This is problematic, because polypropylene degrades slowly in landfills. It also includes toxic additives such as lead and cadmium. In addition, burning thermoplastics discharges dioxins and vinyl chloride into the atmosphere.
Since these plastics can be cleaned of contaminants with adequate heat, and then blended with virgin polypropylene to make recycled plastic, this is a win/win proposition, eliminating the danger of improper and dangerous disposal of these plastics.
The Takeaway
So what can you do?
- First of all, read everything you can get your hands on regarding environmentally friendly commercial printing products, and then ask your printing suppliers about their participation in recycling programs. This includes inks and papers.
- Ask how your printers recycle paper waste. Probably they have vacuum hoods and hoses snaking throughout the pressroom that collect the paper scraps and fibers and deposit them in balers (to make bales of paper, like bales of hay) for shipping back to recycling plants.
- Ask about UV inks. But be aware they they may cost more than conventional inks.
- Study the environmental impact of the various commercial printing technologies, including offset lithography, digital printing, gravure, flexography, screen printing, etc.
The post Custom Printing: Choosing Sustainable Inks and Papers appeared first on Printing Industry Blog.
* This article was originally published here
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