Radiation Curable Coatings

Radiation curable formulations, used in coatings, inks, adhesives and electronics, are cross-linked by high-intensity ultraviolet light or electron beam energy sources. The coating formulations differ from those used in conventional paints and coatings in that the diluent (solvent) and resin (film former) used in thermally cured coatings are replaced by a reactive liquid vehicle in which a pigment and other additives may be dispersed or dissolved.

Radiation curable products are used for a wide variety of applications, which vary in importance from region to region. In North America, the graphic arts sector (which includes overprint varnishes and inks) predominates, with coatings, adhesives and other industries being of lesser importance. In Europe, the wood coatings and graphic arts markets account for about 80% of demand. The situation is different in Asia. Radiation curable film resists, printing plates, semiconductor resists and color filter resists are used extensively for semiconductors, printed circuit boards, printing plates and other components. In Asia (except China), these uses account for 30–40% of the total market for radiation curable products. In China, the major uses of radiation curable products are as wood, bamboo, paper and plastics coatings, accounting for about 60% of the total market.

The following pie chart shows world consumption of radiation curable coatings:

The initial driving force for the development of radiation curable coatings was the possibility of using solvent-free formulations to meet environmental restrictions, but other economic advantages such as low energy consumption, rapid curing and drying, and superior hardness and abrasion resistance properties have become additional factors.

Through the next five years, government regulations in the United States and Europe, especially those concerning air pollution, will continue to be a driving force behind the adoption of new, low-pollution coating technologies such as radiation-cured coatings. However, radiation curable coatings have other desirable properties such as speed of cure; extremely hard, chemically resistant finishes; ambient curing; small application equipment footprint; high productivity; and nonflammability. Still, radiation curable products account for only a small portion of the total coatings market because of high material costs and the need to install new application equipment. These products tend to be used in specific applications only where they exhibit clear-cut advantages over conventional solventborne or waterborne coatings. There is relatively little use on metals, which constitute the largest industrial coating market. Radiation curable coatings account for only 2% of the total global market for industrial coatings.

Among the faster growing sectors for the radiation curable products industry are

• Waterborne systems as replacements for solventborne systems and as dual cure coatings.
• Nanoparticles, which improve certain properties like hardness for clear wood coatings.

Potential new markets include

• Stereolithography, a process in which three-dimensional parts are produced from photosensitive resins.
• Printed electronics, which include any electrical device that is manufactured by printing. UV curable inks and coatings are being developed that have the potential for widescale use in portable photovoltaics, electroluminescent displays, transdermal patches and organic light emitting diodes.

In recent years, the radiation curable industry has grown at nearly double-digit rates. From 2010 to 2015, the average annual growth rate is expected to be 7% globally (volume basis).

Table of Contents