Xerox: Gel ink will be the future

There may come a day when we're buying a tube of ink gel for our printers.Xerox on Thursday said it is previewing what it calls a "cured gel ink technology" that prints on plastic and foil.

There may come a day when we're buying a tube of ink gel for our printers.

Xerox on Thursday said it is previewing what it calls a "cured gel ink technology" that prints on plastic and foil. Xerox's plan is to take digital printers to the packaging market initially.

For now, this ink gel is restricted to commercial printing--brochures, catalogs, cardboard packaging and plastic films--but once the research is turned into a product it could get into the consumer market.

Xerox is showcasing the new ink at drupa, a print industry confab. Xerox said in a statement:

The new cured gel ink holds its shape on nearly any surface because it is not water-based like traditional inkjet technologies. The gel ink has the consistency of peanut butter after it is jetted through the print heads and turns rock hard when exposed to a pulse of ultraviolet light. The result is a crisp, vivid, and long lasting image. Unlike current water or solvent-based inkjet systems, the gel ink won't bleed-through or require dryers and vapor recovery systems, thereby increase print speeds and making the system more environmentally friendly. Developed by scientists at the Xerox Research Centre Canada, the cured gel inks are based on Xerox's proprietary solid ink technology.

Xerox emphasized that the new ink technology is still in the research phase, but "it is clearly an innovation that will take inkjet beyond the products and applications available today."

Xerox's presentation at drupa will be Webcast in a few minutes. During that Webcast Steve Hoover, vice president and center manager of the Xerox Research Center Webster, gave an overview. Here are some of his relevant prepared remarks:

The key challenges of current inkjet technologies is the fundamental incompatibility of the requirement of first squirting the ink thru a small nozzle - the nozzle opening is about 10 microns or 1/10th the thickness of a human hair - with the second requirment that the ink bond to the surface of the paper or other substrate WITHOUT soaking thru the paper or spreading in the paper which causes poor image quality.  These two requirements - ink thin enough to jet thru an nozzle - but thick enough to not soak thru the paper cannot both be met by current inkjet technologies. This is because to squeeze a drop out of an inkjet nozzle the liquid must be about the consistency of water.

Compare that to the consistency of lithographic or flexographic inks which are more like toothpaste.  So, current inkjet inks are very watery and eject fine from nozzles but when they hit the paper they are still very thin and so they soak thru the paper or spread along the paper fibers causing poor image quality - unless you use very expensive special papers.  Again compare this to lithography or flexography - which allow you to use any paper, film or foil you want.  This is because those inks are very thick when printed and give outstanding image quality on a broad range of surfaces.  Xerography which uses a toner that is mostly plastic which melts in a fusing step has similar performance to lithographic inks and is compatible with a broad range of media for the same reason - it doesn't soak thru or move around a lot on the paper.  In addition to the image quality and media compatability issues caused by current inkjet inks being over 90% liquid --often water--that liquid also must be removed from the paper after printing.  This leads to large complex and high energy drying sytems and if solvent inks are used, expensive vapor recovery systems.  The environmental impact of all of that energy consumption to remove the water or other liquid must be considered and should be avoided if possible.

All of this created the innovation imperative for the Xerox Research labs:  could we develop an inkjet technology that had the benefits we all want from inkjet of simplicity, productivity, low cost and reliability but combine those with the broad media latitude of xerography, lithography and flexography?  Could we create an ink that has the consistency of water when ejected from an inkjet nozzle but the consistency of toothpaste when it hits the paper and sticks permanently to any substrate - papers, metal foils and plastic films?  If we can create this we have created a truly disruptive innovation - one that will make a real difference to our customers business.  The answer we believe is YES.  In our labs we have created such an ink, a compatible long life and robust scalable print head and the print process necessary to put it all together.  Now again, this is truly a look inside our research labs and we are still at the technology development stage but we are so excited that we wanted to share this breakthrough with you.

This is a microscopic image of our solid ink on paper. Notice the well formed dots - no bleed through - no dot spreading.  Notice the bright vibrant colors.  This has given our solid inks great performance in the office.  On standard office papers we have no showthrough, vibrant colors and no dot spread and noise.

But, our current solid ink technology has clear limitations for production.  For applications that demand low run cost on thin, plain or recycled papers such as transactional/promotional documents solid ink will be advantaged due to the low cost and superior image quality over standard water based inkjet.  However, on the broader paper range that production customers desire - a wide variety of coated papers and even metal foils and plastic films  - a new breakthrough is required.  Our solid inks can print on coated papers but only on specially designed papers with a unique coating.  For all of the reasons I have discussed none of water, solvent based or our solid inks will meet the total requirements of production to print on a wide range of papers, foils and films.  A real breakthrough is needed to take the industry where it wants to go with inkjet technology.

That breakthrough is our cured gel ink.  This ink is a liquid with a consistency near water at an elevated temperature - near 100 degrees centrigrade - but that has the consistency of toothpaste when it comes in contact with paper or nearly any other substrate - including not only coated papers, but also metal foils and plastic films.  So when it contacts the paper it does not soak through to the back or spread out unevenly creating poor image quality.  No, instead it sticks right where it lands giving precise and consistent dot formation and bright and vibrant colors and noise free images.

Here you see these drops of ink hitting the substrate and turning into a gel when they hit the paper.  They hit and stick, forming precise dots reliably and repeatedly.  But that still isn't enough.  Not only must the drops stick there when they lands but the final image must be robust.  It must be able to undergo the rough handling and abuse and elevated temperatures that finished documents such as automobile manuals subject to over 70 degrees centrigrade in a automobile glove box, or packaging materials shipped long distances or mail transported across a desert in the back of a truck.  So, we add one final step.  We expose the ink on the paper to UV light which initiates a chemical curing process that hardens the ink into a thin robust film able to undergo significant abuse and not peel, scratch or rub off even at elevated temperatures.

Together these steps of heating the ink to be thin enough to jet, having the ink turn into a gel the consistency of toothpaste on contact with the surface and then curing the ink to get a robust and permanent image mean we can print on nearly any surface.  Here you see images from our test fixture showing printing not only on paper, but on clear plastic film and metal foil.  Our cured gel ink technology set breaks previous tension between getting an ink thin enough to squeeze through an inkjet nozzle and an ink thick enough to act like lithographic and flexographic inks on paper so that you get the image quality you need.  And the curing process gives you that image quality permanently providing a very robust image able to survive standard handling practices in your finishing equipment as well as in shipping and use.  And it does this without the complex and energy intensive drying or solvent recovery steps other inkjet technologies require.