diisononyl

Diisononyl is a term used in chemical nomenclature to describe esters formed from two isononyl groups linked to a single diacid moiety. The isononyl group is derived from isononyl alcohol, a branched C9 chain. In practice, diisononyl esters are high-molecular-weight, hydrophobic plasticizers used to soften polymers, especially vinyl chloride polymers (PVC).

Two common diisononyl esters are diisononyl phthalate (DINP) and diisononyl cyclohexane-1,2-dicarboxylate (DINCH). DINP is one of the most widely used plasticizers for PVC, employed in cables, flooring, automotive interiors, and consumer goods. DINCH is a non-phthalate alternative promoted for lower health concerns, used in similar applications where migratory potential is a consideration.

Chemically, diisononyl esters are produced by esterification of a diacid (such as phthalic acid or cyclohexane-1,2-dicarboxylic acid) with isononyl alcohol, followed by purification. They are characterized by relatively low volatility and high resistance to extraction, contributing to durable flexible plastics.

Safety and regulation: Diisononyl phthalates have been subject to regulatory scrutiny due to potential reproductive and developmental effects in animal studies at high exposure levels; many authorities restrict or monitor their use in certain consumer products, especially children's toys and childcare articles. DINCH, promoted as a safer alternative, has undergone toxicity evaluations and is adopted in regions with phthalate restrictions. Overall, regulatory status varies by jurisdiction, and manufacturers may substitute diisononyl phthalates with non-phthalate esters where required.