Over the past few years, many different aspects of coatings technology have been inspected under the verbal microscope of these editorials and their associated technology reviews. It has become progressively more difficult to identify new areas of technology which are of general interest, and to bring this series to a close I have chosen to look further ahead than usual, to speculate on ideas and issues which may be relevant many years from now.

All attempts to predict the future will fail; the most important variables are often the ones which are unimaginable. New markets will open up, new technologies will emerge to meet their demands, and some of these issues are considered in the accompanying technology review, but environmental pressures and regulation must be considered as the main identifiable factors which will have the greatest influence on shaping our industry in the future; indeed this statement has already become a cliché.

While industry complains, with justification, about the burden and problems imposed by environmental regulation, closer examination of the global environment suggests that these regulations and even industry initiatives which may run ahead of legislation, will be inadequate for the long term.

Each turn of the environmental screw exposes us not simply to stricter regulations but to different kinds of regulations. We must now deal with countless regulations covering toxicity and pollution issues, VOC emissions and in some areas, recyclability. But what is notable about this approach is that it is completely fragmentary, both in the way individual regulations are drafted and in the way in which pressures put on industry in one part of the world lead to production being moved to another where regulation is less strict.

The world itself does not measure where pollution is produced; it only measures pollution; and it is already well known that industrial fluorochemicals have made their way all around the world. The long term solution (though it faces both practical and political problems and so will probably be a very long time coming) is surely to measure the eco-efficiency of a process as a whole - including the coating.

That requires a shift in emphasis from what can easily be measured (the use of individual ingredients) to more difficult aspects such as the use of natural resources, the durability of coatings and the energy efficiency of production processes.

Green chemistry and beyond

Twelve 'principles of green chemistry' were set out by Paul Anastas and John Warner in Green Chemistry: Theory and Practice in 1998 (See also www.epa.gov/greenchemistry/pubs/principles.html). The twelve points overlap to some extent, as suggested by the way they have been grouped into the table shown here.

Admirable as these principles are, do they go far enough? If we were to consider some idealised principles of 'green manufacturing' which could be applied to all of industry, we would have to add:

Recent European directives have addressed the second point in relation to vehicles and electronic goods, which must now be largely recycled. And while we cannot in general apply this principle to coatings, which in most situations must be processed along with their substrate in recycling operations, there are known ways of producing ink binders which will degrade to order, simplifying the task of deinking waste paper.

Supply issues: facing up to biomarket problems

The rising price of oil, the huge variety of raw materials available from natural sources and a desire for a 'green image' are all increasing interest in the use of naturally derived raw materials.

Early paints necessarily used these natural raw materials as binders, and some historic materials are still widely used today, at least in modified forms. As discussed in the accompanying technology review, there is a great deal of potential for increasing our use of natural raw materials.

But this is not automatically the most appropriate solution in environmental terms. Some sources have suggested that certain types of biofuels may cause just as much environmental harm and carbon dioxide emissions as fossil fuels; and if that is true for biofuels, might it not also be true for biopolymers in plastics and coatings?

One of the great advantages claimed for bioplastics is that they are biodegradable. Well, yes - but so are polyethylene and some other petroplastics; it is the antioxidants and stabilisers added to extend their lifetimes which - by definition - make them harder to degrade and - in general - make their breakdown products less innocuous.

On top of this, we have to look closely at supply problems. A consideration of the overall market for natural oils and fats makes worrying reading. World production of vegetable and animal fats has been steadily increasing, from 80 M tonnes in 1990/91 to 100 M tonnes in 1998 and 154 M in 2006/7. By far the greatest expansion has been in palm oil production, up from about 11 M tonnes in 1990/91 to 38 M tonnes in 2006/7, with soy oil also showing rapid growth. Part of this growth is attributable to increasing the acreage devoted to oil-bearing plants, but recent high grain prices are causing some farmers to reduce oilseed acreage and world oilseed demand currently exceeds production. The Hamburg-based analysts Oil World estimate that global stocks should be sufficient to cover the deficit in the short term, but by next year, acreage must increase or prices will soar. They have also warned of an impending food crisis as increasing amounts of farmland are devoted to biofuels production. [The EU currently converts about 65% of its rapeseed (canola) usage to biofuels.]

The German company Cognis (formerly part of Henkel) has a long history of involvement in the use of naturally-derived oleochemicals. Recently, a company spokesman noted that about 35% of its raw materials were derived from natural sources, compared to about 5-10% for the chemical industry overall. That gives some idea of the potential scale of demand. Only a small proportion of current production of vegetable oils and fats is converted to oleochemicals; the industry's potential demand therefore exceeds current total production levels.

Thus, the obvious way to make 'green paints' may not be the best one; as in the case of biofuels, it may pay to look at waste and by-products. This does not necessarily mean lowering technical standards - consider the case of cardanol curing agents, derived from cashew nut shells and perfectly capable of competing on technical grounds against oleochemical rivals.

Performance demands

A theme which has recurred many times in these columns is that the need or desire to reformulate coatings in order to meet tougher environmental demands has often led indirectly to the production of coatings able to meet higher performance requirements. The indications so far are that this can be maintained; and it will have to be maintained if we are to solve the long term supply/demand equation. We have come a long way in matching environmental demands with high performance; but we still have a long way to go.

But, to end on a lighter note, the ultimate question for future high-performance paint technology must be: what kind of paints do aliens use on their UFOs?

Should you have any comments or feedback, please contact me.

Sandy Morrison