I found this technical information by googling:
"Di-isononyl phthalate (DINP) is a commonly used plasticiser, 95 per cent of which is used in PVC applications. More than half of the DINP used in non-PVC applications involves polymer related-uses (e.g. rubbers). The remaining DINP is used in inks and pigments, adhesives, sealants, paints and lacquers and lubricants.
DINP is a mixture of isomers that have alkyl chains from 8 to 10 carbons long, but the largest portion of the mixture has chains composed of 9-carbons.
There are two different substances attributed to the names 1,2-Benzenedicarboxylic acid, di-C8-10-branched alkyl esters, C9-rich or di-“isononyl” phthalate (DINP). DINP 1 (CAS 68515-48-0) is manufactured by the “Polygas” process whereas DINP 2 (CAS 28553-12-0) is n-butene based. Under the EU risk assessment these substances have been considered equivalent from a health and environmental perspective, and as such a single EU risk assessment has been conducted for DINP."