2,2,4-Trimethyl-1,3-Pentanediol Diisobutyrate — Frequently Asked Questions

Fundamentally. The mono-ester retains a free hydroxyl, which gives it water compatibility and allows it to evaporate out of the film after coalescence, so it is a coalescent. The di-ester has both hydroxyls esterified, making it fully non-polar and effectively non-volatile, so it stays in the film permanently and acts as a plasticiser instead.

Because it delivers efficient plasticising without phthalate chemistry, at a time when ortho-phthalates such as DEHP and DBP are classified as reproductive toxicants and restricted in consumer applications. Its low molecular weight gives good efficiency at modest addition, and its low volatility limits the fogging and migration that afflict cheaper low molecular weight plasticisers.

It is the film that forms on the inside of vehicle glass as plasticiser evaporates out of trim and dashboard materials and condenses on the cold windscreen. It is both a visibility and a durability problem, since the material leaving the polymer is also making it stiffer. Low-volatility plasticisers are specified specifically to avoid it.

As a viscosity reducer in plastisols, where its low viscosity allows a lower plasticiser level or a higher filler loading at the same processability, and in caulks, sealants, adhesives and inks. It is also used as a coalescent where some permanent softening of the film is actually wanted rather than avoided.