Xerox EA Technology – Environmental Triple-Hit
By Gail Nickel-Kailing on December 15th, 2008
With Xerox EA technology, the question is: What’s old and what’s new?
Since 2001 Xerox has manufactured dry toner by using a novel process called “Emulsion Aggregation” (EA). EA yields smaller, more consistent particles and requires less energy than traditional toner manufacturing methods that incorporates pulverization of toner composite chunks.
Hadi Mahabadi, Xerox vice president and director of Xerox Research Centre of Canada (XRCC), spoke to WhatTheyThink.com and explained why the new Ultra Low-Melt EA Toner is a triple-hitter when it comes to environmentally friendliness.
WTT: In Xerox’s recent announcement, Xerox Preparing Production of Ultra Low-Melt EA Toner, there was reference to previous methods of toner manufacture as “an energy-intensive mechanical process.” Please explain why the process used to manufacture EA toner is better and takes less energy.
HM: The conventional way of making toner is a mechanical process that involves mixing toner ingredients into a polymer composite and then pulverizing them to micron size toner. This is a top down mechanical process which requires a high level of energy and yields toner of inconsistent size and shape.
WTT: It’s similar to dropping a bunch of plastic chunks into a blender and grinding them up, correct?
HM: Yes, you’d grind them into small pieces, but if you looked closely you’d see that they were all different shapes and sizes. The resulting mixture would need to be classified into three size categories: correct; too fine; and too large with finer and larger size toner returned to the process, resulting in a low yield.
The conventional process was not only energy intensive; it didn’t yield 100% of what was needed in a single pass. Even the usable fraction was made up of different sizes and shapes particles, because the grinding was not a controlled process.
That was the way we and other companies used to make toner and even now, some toners are made using this conventional process.
Realizing that it would be better to make toner using a “bottom up” process, which would build the toner particle up from very tiny – nanometer-sized – toner ingredients, the scientists at the Xerox Research Centre of Canada started looking for a better way to make toner. The outcome was a process based on nanotechnology methodology, which has been used by nature to produce a variety of particles. We called this process the EA (Emulsion Aggregation) process.
The EA process for turning nanometer-sized ingredients into micron-sized toner particles is a controlled process. We can control the size, shape, and structure of resulting toner particles. If we want the toner particles to be spherical, potato-shaped or some other non-spherical form, we can make it.
And we can also control the structure. For example, the toner can be made such that it is built up layer by layer, a feature which provides us certain advantages.
Compared to the conventional process, manufacturing toner by the EA process requires 30-35% less energy per pound of toner made.
WTT: I’m not a chemist, but growing particles in a liquid makes it sound like you’re growing crystals.
HM: It is similar, but not exactly the same. A simple analogy to the EA process is aggregation of the fat particles of milk into a larger size. Milk is actually made up of very fine fat particles dispersed in water and if one adds in a little bit of vinegar, the particles of fat aggregate into larger particles. If you did that in your kitchen it would not be a controlled process; but conducting such an experiment under controlled conditions could result in fat particles of the same size and shape.
In the EA process, the toner ingredients, which are very small in size and dispersed in water, are introduced into a reactor and mixed, then an aggregating agent is added causing the ingredients to form a loose aggregate. The loose aggregated particles are then heated to form final toner particles. This process requires less energy to produce toner with higher yield and because it is a bottom up process, it’s easier to stop at a smaller size to make smaller size toner.
Why is small size toner important? Because smaller size toner reduces toner usage and enables prints with better image quality. For example, a cartridge of 5 micron toner can produce double the number of printed pages compared with a cartridge having the same weight of 9 micron toner.
As I indicated earlier, the EA process requires 30-35% less energy. Combining the manufacturing energy savings with the additional pages that can be printed by smaller size EA toner, EA toner enables a saving of close to 70% less energy per printed page compared to conventional toner.
WTT: Your chemical reaction actually takes place in water. Can you recycle or reuse the water?
HM: Yes, we reuse the water in the reactor for the next round of processing. Water is, of course, an environmentally friendly and safe medium. Some manufacturers use solvent as the medium for making toner, but Xerox EA manufacturing utilizes water.
WTT: You mentioned that you can build toner particles in layers. What is the last layer and why?
HM: Before answering your question, I need to explain what the toner components are. There are three major components that make up toner: the colorant or pigment; polymer or resin; and wax or oil. When particles are pulverized in conventional toner manufacturing methods, some of these components may end up on the surface, which may not be desirable.
By building up the toner using the EA process, we can control what is on the surface. As we don’t want wax or pigment to end up on the surface of toner, the last layer of Xerox EA toner is resin or polymer only. This way, four different color toners, with different pigments and pigment chemistry, will behave the same and we can control them better in the Xerographic subsystems. It makes the process of moving the toner from the cartridge to the paper simpler.
WTT: Now Xerox has announced a second generation of EA toner – EA Ultra Low Melt Toner – that melts at a lower temperature. What is the difference between the new EA toner and the old one?
HM: The manufacturing process is very similar, so the new EA toner has the same benefits from the manufacturing point of view. However, there are additional benefits for using the new EA toner for printing.
Because the toner melts at a lower temperature – as much as 45°F lower – it requires less energy to fuse the toner to paper without compromising image quality or any other performance.
This means in addition to saving energy during manufacturing and being able to print more pages with EA toner, this new EA toner enables significant energy saving during the printing too.
WTT: Sounds like a triple hit to me!
