Nanotechnology is Impacting Inks, Pigments, Printing
By Sean Milmo, European Editor
Nanotechnology is expected to have a major influence on most areas of science and technology. It is already starting to have an impact on printing, particularly on the development of printing materials.
A lot of this development work in the printing sector is being done by suppliers of ink raw materials, many of them European companies, as well as by pioneers in the field of ink jet printing. As a result, materials makers, particularly producers of pigments, dyes and colorants, will be in a strong position to shape the future of ink technologies.
The main players in opening up new horizons through nanoscale research could be vertically integrated companies active in both the manufacture of materials and inks. Often they will be allied with start-ups specializing in nanotechnology research.
Large companies will have a key role, at least initially, in nanotechnology in printing because of the expense of nanoscale research, especially the need for sophisticated microscopic equipment for production and quality control of nanomaterials.
In the longer term, there are likely to be opportunities for smaller ink producers and printers as nanoscience expands printing beyond graphics and into the manufacture of a wide range of electronic devices.
What is Nanotechnology
The Greek word ‘nano’ – meaning dwarf – refers to a dimension which is one thousand times smaller than a micron so that one nanometer (nm) is one billionth of a meter. Ten hydrogen atoms lined up together would measure around one nanometer across.
The term nanotechnology usually signifies the application of science to substances between 100 nanometers and a tenth of a nanometer in size, although sometimes it encompasses particles as large as a few hundred nanometers.
Nanoscale materials are not entirely new. The difference today is that with the help of modern microscopes, scientists can control and manipulate nanoscale structures at the level of atoms and molecules.
“Nanotechnology is both overhyped and underplayed – a long way from delivering on its potential (but is) at the heart of applications that are already making money,” concluded a recent joint report on the subject by the 3i, a U.K.-based venture capital company, and the Economist Intelligence Unit, London.
Pigments and Coatings
In a global survey of scientists, investors and entrepreneurs active in nanotechnology, the report found that a third of respondents – by far the largest proportion – thought that ‘smart’ pigments and coatings would be the most thriving area of nanotechnology development in five years.
This view stems from the fact that nanotechnology has already been making inroads into printing and coating, especially pigments.
Chemical companies with extensive research capabilities and a wide variety of manufacturing plants are able to take advantage of the current strong demand for nano products in inks and coatings.
“We have a good starting position in the nanotechnology sector because of our know-how in a range of technological areas like polymers, dispersions, organic and inorganic chemicals, as well as in analysis,” said Stefan Marcinowski, BASF’s research executive director, at a recent seminar on nanotechnology organized by BASF.
“For decades, BASF has been manufacturing products that you might not necessarily associate with nanotechnology,” he told the meeting at Mannheim, Germany. “But their product properties are determined by nanoparticles and nanostructures.”
BASF, which makes inks, pigments and colorants as well as emulsions and dispersions, estimates that nanotechnology products already make up 10 percent of its sales, while it also allocates 10 percent of its R&D budget to nanotechnology.
Among its leading products in the area are nanoscale pigments. These include titanium dioxide for inks and cosmetics which, with particles of 50-100 nm in size, have a high capacity for light absorption. The company also makes optically-variable pigments comprising several layers, each a few hundred nanometers thick.
BASF is currently working on making nanomaterials to provide colors without the use of dyes or conventional pigments. The colors are generated by dispersions of uniformly sized nanoparticles in the same way that color is created by the ordered, textured surface of butterfly wings.
The company has taken advantage of its know-how in polymers to produce a film of nanostructured crystals made from polystyrene and polybutylacrylate. In the printing sector the nanostructures could be used in packaging film and decorative papers.
“Potential applications in printing could include not only offset printing with its highly viscous organic inks, but also flexographic printing and gravure printing, in which low-viscous, water-based inks can be used,” said Reinhold Leyrer, a researcher in acrylic polymers at BASF.
Among the company’s research projects in nanotechnology is the development of hyperbranched polymers from polyurethanes, which have a dendrimer-type structure similar to that of a tree. The research is a joint effort between BASF’s R&D teams in plastics and printing products.
The company believes the polymers will solve the problem for printers of having to use different ink systems for printing on polar polymer packaging like polyester and polyamide and non-polar plastic such as polyethylene and polypropylene. With the new plastic, there is no need for a change of inks.
“Because of the large number of functional groups on the molecule surface (of the hyperbranched polymer), there are enough anchor groups to allow the ink to dock onto adhesion points on the plastic surface when the print is applied,” Bernd Bruchmann, a BASF polymer research scientist, said. “The highly functional active substance acts as a nanometer-scale anchor for optimum adhesion of the pigments to the plastic surface.”
Clariant, whose main activity in the printing sector is the supply of pigments for printing inks, is marketing a coating for ink jet papers which comprises a colloidal silica nanostructure. It deals with the problem of poor adhesion of ink jet inks to the surfaces of some papers, particularly those used for printing photographs.
The coating forms pores only a few nanometers in diameter in which the ink droplets are trapped and then quickly dry.
“Ink jet inks cannot easily penetrate glossy paper, which is what a lot of people want for their photographs, so a coating with nanopores is a solution to this difficulty,” said Frederic Mabire, Clariant’s business line manager for surface paper chemicals.
“With the help of our coating, the quality of ink jet photographs is approximately 90 percent of that of traditional photographic paper with silver halides,” he added.
Degussa, a leading producer of carbon black and metal oxide pigments, employs various gas-phase reactors to make nanoparticles for use in a wide range of sectors, including inks.
“The type of reactor and its operating parameters control the size and form of the particles, along with their characteristics, opening up completely new markets and applications,” said Michael Kramer, research assistant at Degussa’s nanomaterials project. “The list of these applications includes not only catalysts, capacitors, glasses and paints, but also pigments, multi-functional fillers, ceramic and metal materials and sensors.”
One market opened up by the company’s nanoparticles technology is pigments for ink jet inks, which need to be an ultra-small size to work properly with printheads and to achieve sufficient stability on substrate.
Degussa has developed a reactor which applies laser energy to evaporate metal oxides which are then formed into nanopowders by the condensation of the vapors.
Buhler AG, the Swiss-based manufacturer of industrial grinders, mills and extruders, has introduced a bead mill which makes nanoscale pigments for printing inks. The machine has ceramic beads of less than a millimeter (mm) in diameter.
With beads of 0.8 mm the mill has an output of 600 kilograms per hour, twice as much as can be obtained with old machines. With beads of 0.3 mm, the particles formed were as small as 50 nm to 120 nm, with an output of approximately 50 kg/h.
NTera, Dublin, Ireland, which has an alliance with Merck KGaA, the German producer of liquid crystal display chemicals and pigments, is likely to be one of the first European nanotechnology start-ups to launch a nanomaterial electronic display system.
It has formed a partnership with Tew Engineering, a leading U.K. manufacturer of electronic transport signage, to produce an information display for railway stations which will have the visual quality of print on paper.
The display comprises metal oxide particles of approximately 20 nm which are coated with electrochromic dyes. The particles are semiconductors which change color when electrically charged.
The particles are made through a system of chemical synthesis which controls their shape and size. They are then mixed into a paste before being applied by screen printing to a glass substrate.
“Because the displays will have the optical properties of the printed page, they will be far easier to read in daylight than other electronic displays,” said David Corr, R&D manager at NTera. “We expect the displays to be tested in railway stations in the U.K. before the end of the year and will soon seek to expand into information displays at airports as well.”
Technologies like NTera’s point to the way nanomaterials in displays and printing are likely to develop. Instead of relying on mechanical methods to break down materials into small particles, most companies involved in the production of nanomaterials will use chemical synthesis, self-assembly and related systems.