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Alkyd surface coatings continue to be one of the largest types of coating
used in the world, despite the increasing use of other film formers. The success
of alkyd resin systems is a result of their relatively low cost, versatility
and long familiarity with users. They can be tailored to meet a variety of
end-use requirements through the choice and ratio of reactants and/or modifiers.
Alkyds are used extensively in architectural coatings, product finishes and
special-purpose coatings. Polyesters, also referred to as oil-free alkyds,
are made in the same equipment as alkyds and use many of the same raw materials.
Polyesters are used almost exclusively in industrial baking finishes.
Despite the continuing decline in the marketplace in North America, Western
Europe and Japan, alkyds remain one of the leading types of coatings used in
the industrial marketplace.
The following pie charts show world consumption of alkyd/polyester surface
coatings.
World Consumption of Alkyd/Polyester Surface Coatings—2006
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In North America, Western Europe and Japan, consumption of alkyds has diminished
over the last thirty years. In the architectural or decorative coatings market,
solventborne alkyds have been replaced with waterborne emulsions due to lower
odor, lower solvent content, easy cleanup and fast drying properties. However,
these emulsions do not display the same level of performance in leveling, adhesion,
gloss and certain resistance properties. These drawbacks have stalled the conversion
from most solventborne gloss trim and light maintenance coatings, so solventborne
alkyds still remain a sizable factor in the coatings industry. However, restrictions
on the use of paints are becoming tighter in certain parts of the United States
and in Europe, and will forbid the use of conventional low solids (i.e., high
solvent containing) solventborne coatings. In the next five years, the types
of resins used in these regions in certain applications will change significantly.
Producers continue to develop new and improved systems for high-solids and
waterborne formulations to meet increasingly stringent air pollution regulations.
The industry seems pessimistic on the use of higher-solids alkyds, but is optimistic
that waterborne alkyds can be developed with properties comparable to solventborne
systems. Generally, though, these environmentally friendly systems are considerably
more expensive than the conventional systems, and have some technical drawbacks.
Polyesters are offered in high-solids, waterborne and powder coatings.
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