Handbook of Solvents - George Wypych - ChemTech - Ventech!

974 David Randall
50-60% glutaric, 20-30% succinic. Esterification using isobutanol is then performed and
the product is isolated following distillation. Coasol was introduced in the early part of last
decade as a coalescing agent to the aqueous based coatings industry.
Coasol has excellent coalescing properties and is compatible with virtually all paint
systems. It has very low vapor pressure at ambient temperature which ensures excellent
plasticization throughout the film forming and drying process. Its extremely low odor also
significantly improves the general view that aqueous systems have unpleasant odors. This is
almost always as a result of the coalescing solvent. Its resistance to hydrolysis allows its use
in a wide variety of formulations, including those, which require adjustment of pH to basic
conditions.
It rapidly biodegrades, both aerobically and anaerobically, since, as an ester, it is
readily attacked by ubiquitous bio-species. Finally, its toxicological profile is virtually benign,
so in use it can be handled with confidence in most working environments. Its properties
are summarized in Table 14.19.2.1.
Table 14.19.2.1. Properties of Coasol
Physical Characteristic Coasol Comments
Boiling point > 275°C Not a VOC
Evaporation rate < 0.01 (Butyl acetate = 1.0) Slow, allowing excellent coalescence
Freezing point < -55°C No freeze-thaw issue
Water solubility 600 ppm
Hydrolytic stability Very Good No hydrolysis in normal use
Color 5 Hazen units Imparts no color to coatings
Coalescing efficiency Excellent for most polymer systems
Biodegradability 80% in 28 days Biodegradable
Odor None discernible
Toxicology Oral LD50 (Rat) >16,000 mg/kg Essentially non toxic
14.19.2.7 RECENT ADVANCES IN DIESTER COALESCING SOLVENTS
We have also prepared the di-isopropyl esters of the higher adipic content stream. This has a
vapor pressure similar to that of Coasol, but is slightly more water soluble. Finally, we have
manufactured di-isopropyl adipate, which has the highest boiling point, the lowest vapor
pressure and the lowest water solubility of all of this range of products. These preparations
were undertaken to add to repertoire of products to suit the diverse requirements of the formulators
of aqueous based systems.
In virtually all cases, the dibasic esters gave a significant improvement in efficiency in
reducing the MFFT for a given quantity of additive. The attempts are made to offer a tailor
made solution to each individual polymer system employed in the development of aqueous
based systems. The dibasic esters of the AGS acids group offer the opportunity for fine tuning,
with the added advantage of low odor, low toxicity and “excellent” VOC status.