In a laboratory at the Applied Chemistry Division of the Union Chemical Laboratories of the Industrial Technology Research Institute (ITRI), an ear-shattering mixer works through the night, producing one barrel after another of thick red, blue, and yellow pigments. The pigments are much more refined and glossy than what you can see on the market. It is expected that the first batch of "nano-pigment inkjet ink" will be available in mid-2003. This will not only be a first in Taiwan, but will put the company on the cutting edge worldwide.

Small but tough

"The ink currently used in color inkjet printers is dye-based," explains Yang Wun-dar, president of Tatung Coatings, which is cooperating with ITRI on this project. Dye-based ink is resistant to neither water nor light, blots at the first drop of H2O, and begins to fade as soon as it is exposed to light. As a result, the search has been on for an ink material that will not dissolve in water and will not fade "even if exposed for ten years."

The problem is that while the alternative to dye-that is, pigment-does not dissolve in water, it does something else in liquid that is also problematic: It takes the form of suspended particles. If the particles are too big and heavy, there will be sedimentation rather than a smooth texture all the way through. Since the nozzles on an inkjet printer are miniscule, with a diameter of only ten or so microns, the ink particles must be very tiny as well so that more than 10,000 per second can be smoothly fired though the print head. The pigment-based inkjet ink currently on the market has particles of a diameter larger than one-tenth of a micron (100 nanometers), so that print quality is by no means ideal.

Based on these considerations, the key is to refine pigment to the smallest possible size. Thus, ITRI and private firms have entered into a cooperative research program, beginning with research into milling and impacting of pigment particles.

"To make an analogy, if you want to crush bacteria, you can't do it with anything as clumsy as your hands, but have to use a tool as small as the germs themselves," says Chang Yih-her, director of the Advanced Coating Department at ITRI's Applied Chemistry Division. In order to impact minuscule particles smaller than the eye can see, the research team tried a number of approaches before finding the right formula for their grinding medium. Their medium, which includes glass beads, zirconium beads, and various kinds of polymeric beads, greatly increases the number of collisions.

Because the structure of particles becomes increasingly consolidated as they get smaller, ever greater impact force is required to smash them, at which point the entire design of the impact device must be rethought. Of the three primary colors used in printers, particles of 30 nanometers have already been achieved with red and yellow, while blue is still a bit short of that threshold.

Breakthroughs

Of course, all matter is agglomerate, and it is by no means easy to smash a particle. And if the fragments adhere again, then hasn't all the effort been for naught? The key here is the use of a dispersant to keep the fragmented particles from re-agglomerating after refinement. At Tatung Coatings, this is right up their alley.

Founded in 1958, Tatung Coatings, a division of the Tatung Company (one of Taiwan's leading makers of electrical products), at first served as the in-house pigments manufacturer, producing industrial products like baking enamel and spray paints, which were used on products made by the parent company. Thereafter, Tatung Coatings expanded into many other related lines, including construction paint, cationic acrylic electro-deposition coatings, resistor coatings, and universal colorants (used to tint paints). However, until the 1990s, they always stayed "in the paint."

The mid-1990s saw a crisis in the local paint industry as production costs increased in Taiwan. Most traditional paint factories closed or moved overseas, while those that remained were forced to make layoffs or cut back salaries.

In 1998, Tatung Coatings completed their new factory in Kunshan, China. Yang Wun-dar, who became president of Tatung Coatings that same year, decided that he was going to take his Taiwan factory on a different trajectory and escape the shadow hanging over this sunset industry.

Thereafter, guided by the instruction from Tatung Coatings' Chairman and Tatung Group President Lin Wei-shan to "move in the direction of specialty chemicals," Yang contacted ITRI and joined the printer-ink research program. After nearly four years of effort, the laboratory now has the capacity to produce 50 liters of pigment at a time. While this is still far from the one-ton-per-batch requirement of mass production, there is clearly light at the end of the tunnel.

R&D is the only way

As newcomers to the printer-ink field, Yang says that their first step will probably be into the generic ink market, without emphasizing any particular brand name. The maturation of the technology for nanoscale manufacturing not only will greatly assist the upgrading of their original paint operations, it will also allow Tatung Coatings to break into the photocatalytic nanoscale titanium dioxide business, which has been a hot topic of late. Currently nano-scale production for the market is done using the sol-gel method, which is very expensive. If production can be done using the dispersion method, costs could be reduced sharply.

Looking back at the transformation of these past few years, Yang Wun-dar intones: "One thing is very obvious-with research and development, sales have continually increased." He bemoans the fact that there are many areas in which Taiwan firms could strive to upgrade, if only businessmen had the will and the skill to move steadily and stably one step at a time. The fruits that Tatung Coatings have reaped from this approach are sweet indeed.

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The print quality achieved using micron- or nano-scale pigments is definitely superior. Posters, Chinese painting, and inkjet printers are all possible applications.

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To reduce pigment particles to nanoscale sizes takes a powerful mill and the right grinding medium. Tatung Coatings uses adapted German machines to do the job.