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One-Component Waterborne Polyurethane Coatings
One-component waterborne polyurethane systems can be derived from
polyurethane dispersions or blocked
polyisocyanates. These products are sold under the tradenames
Bayhydrol®,
Impranil®, Baybond®
and Bayhydur®.
One-component systems using polyurethane dispersions are fully reacted
polyurethane polymers dispersed in water (organic solvent could be
employed as well). Film formation occurs at ambient or elevated temperature
by evaporation of the water and/or co-solvent, if present, at which
time the polymer particles coalesce. Polyurethane dispersions may
be used as the sole resin or blended with other resin systems, such
as acrylics. Preparation of waterborne polyurethane dispersions is
done by emulsification of hydrophobic polyurethanes in water with
the aid of suitable external emulsifiers built-in hydrophilic groups.
These one component fully reacted polyurethane resins have been modified
to provide finer particle size, better dispersion stability, and reduced
water sensitivity of the polymeric film after evaporation of the water.
An example of the formation of a polyurethane dispersion is shown
below.
One-component waterborne systems can also
utilize blocked polyisocyanates. To learn about blocked polyisocyanates,
click here.
For additional information
about one-component waterborne polyurethane coatings, please visit
our literature request
section.
The information above
was obtained from Bayer's "Waterborne Polyurethane Coatings: One
and Two Component Systems" technical paper by Robert Henderson.
To order a copy, click
here.
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