Diisononyl phthalate (DINP)

Chemical name: Di-isononyl phthalate

CAS No. 28553-12-0 and 68515-48-0

EINEC No. 271-090-9 and 249-079-5

Molecular formula: C26H42O4

Molecular weight: 420.6

Synonyms: 1,2-Benzenedicarboxylic acid; di-C8-10 branched alkyl esters; C9-rich. More

Di-isononyl phthalate (DINP) is a commonly used plasticiser in PVC applications. DINP is a mixture of isomers that have either alkyl chains from 8 to 10 carbons long, but most of the mixture has chains composed of 9-carbons (DINP 1, CAS 68515-48-0) or exclusively C9-chains (DINP 2, CAS 28553-12-0).

There are two different substances classed under the same acronym:

  • DINP 1 (CAS 68515-48-0) which is manufactured by the “Polygas” process
  • DINP 2 (CAS 28553-12-0) which is n-butene based.

Under the EU risk assessment, these substances are considered equivalent from a health and environmental perspective, and as such, a single EU risk assessment has been conducted for DINP.

Processing of DINP

Isononyl alcohol, used in the synthesis of DINP, is produced via either the dimerisation of butene and subsequent hydroformulation or the oligomerisation of propylene/butene. DINP is produced by esterification of phthalic anhydride with isononyl alcohol in a closed system. The reaction rate is accelerated by elevated temperatures (140-250 °C) and a catalyst.

Following virtually complete esterification, excess alcohol is removed under reduced pressure and the product is then typically neutralised, water washed and filtered.

Applications

DINP has a wide range of indoor and outdoor applications. 95 %of DINP is used as a plasticiser for flexible PVC used for construction and industrial applications, and durable goods (wire and cable, film and sheet, flooring, industrial hoses and tubing, footwear, toys, food contact plastics). The other 5% is used in non-PVC applications (e.g. rubbers, adhesives, sealants, paints and lacquers, lubricants).

Some of the main applications of PVC plasticised with DINP include:

  • Automotive
  • Building and Construction
  • Cables and Wires
  • Flooring

Health and Environment

The European Commission has confirmed that DINP poses no risk to either human health or the environment through any current use. The European Commission’s findings resulted from a risk assessment involving more than 10 years of extensive scientific evaluation by EU regulators.

Furthermore, the risk assessment concluded that DINP is not hazardous under any of the EU classification categories.

DINP is not an endocrine disrupter under any of the existing definitions for substances that can be considered to have human endocrine disrupting effects. It is also not a human carcinogen and has never been classified as such by The World Health Organisation’s International Agency for Research on Cancer (IARC).

Toy Restrictions

In the EU, DINP – and also DIDP - is not allowed in toys or childcare items which can be placed in the mouth. On January 2014, the European Commission published its conclusions regarding the re-evaluation of these restrictions concluding that “no unacceptable risk has been characterised for the uses of DINP and DIDP in articles other than toys and childcare articles which can be placed in the mouth”. The existing restriction was maintained (the precautionary restriction has been in place since 2005) but te Commission further concluded that “in the light of the absence of any further risks from the uses of DINP and DIDP, the evaluation of potential substitutes has been less pertinent".

In the report sent to the Commission, ECHA had concluded that “no further risk management measures are needed to reduce the exposure of children to DINP and DIDP”. In the case of adults, the biomonitoring data confirmed that “exposure from food and the indoor environment are not very significant” and, in the case of dermal exposure to DINP and DIDP is “not expected to result in a risk for adults or the developing foetus in pregnant women”. ECHA also indicated that using sex toys containing DINP and DIDP “would not result in any risk”. Overall, the European Chemicals Agency concluded that “no further risk management measures are needed to reduce the exposure of adults to DINP and DIDP.”