DINP AN EFFECTIVE AND EFFICIENT REPLACEMENT OF DOP

Introduction:

DOP, also known as DEHP or DnOP is traditionally used as a general-purpose plasticizer, satisfying wide range of requirements. Plasticizing efficiency of DOP is considered as “1” and efficiency all other plasticizers is evaluated with reference to DOP. Besides, cost of DOP based compound can be reduced by blending it with CPW of appropriate grade in appropriate proportion (70:30), without affecting quality of product.

However, DOP is on its way out due to health concerns.

REACH requirements for DOP:

The latest amendments now require all types of products containing the plasticizers BBP, DBP, DEHP, and DIBP to meet the requirements limiting the quantity of restricted phthalates in any item to?less than 0.1% (1000 ppm) of the entire article’s composition. Most manufacturers must comply with the new directives by 7th July 2020 onwards. RoHS also has the same limits. In Japan it is less than 0.05% or 500 ppm.

It is therefore necessary to use its cost-effective replacement, as good as DOP, possibly better that DOP, without causing health problems. Besides, it should be able to accept secondary plasticizer CP, without health hazard.

Interestingly MCCP is accepted by REACH specifications. MCCP with 52% chlorine is good.

One such replacement is citrate-based plasticizer, but experience is that when CP is blended with it at the same level as in DOP, the CP migrates to the surface of product in due course.

It is interesting to note that phthalate plasticizer with more than 8 carbon atoms are not covered in the list of REACH restrictions. Such primary plasticizers are DINP and DIDP.

DINP is nearer to DOP with lot of favourable properties.

DOP Vs. DINP

1.????Derivation –

DOP or DnOP or Di-Octyl Phthalate or Di Ethyl Hexyl Phthalate is derived by esterification of phthalic anhydride with Ethyl hexyl alcohol (8 C atoms).

DINP or Di-Iso-Nonyl Phthalate is derived by esterification of phthalic anhydride with a mixture of C-8-C10 alcohols. They are phthalates with branched alkyl side chains of varying lengths C8, C9 and C10.

2.????Structure and properties–

DOP, C6H4 (CO2C8H17) has diester structure consisting of benzene dicarboxylic head group linked to two ester side chains. DnOP possesses two linear ester side chains, each with a backbone of 8 carbons.

It has Molecular Weight 390, Boiling Pt 385? C, Freezing point (-)55? C and density 0.99

DINP on the other hand are phthalates with branched alkyl side chains of varying lengths C8, C9 and C10. Average C9.

DINP has Molecular Weight 418, Boiling point 405? C, Freezing point (-) 48? C and density 0.972-0.98.

?3.????Efficiency –

For the same shore A hardness, requirement of DINP is 1.04 Phr to replace 1 Phr of DOP.

Hansen solubility parameters at 25°C, (MPa) 1/2: dD: 16.6 for DINP and DOP.

Source -Anna?Wypych, in?Plasticizers Databook, 2013

4.????Performance -

DINP has a higher molecular weight and longer carbon chain, (Av. Molecular weight 418) as compared to DOP, molecular weight 390. This results in -

a.?????Better aging performance, increasing product life.

b.?????Better anti-migration performance,

c.??????Better anti-extraction performance, and

d.?????Higher high temperature resistance.

e.????Higher permanency and improved resistance for cold outdoor conditions

5.????Other benefits of DINP over DOP -

a.????Electrical insulation performance is better than DOP.

b.????Product with DINP have good water resistance, extraction resistance, low toxicity and aging resistance. DINP is widely used in toy films, wires, and cables.

It can be assumed that DEHP will have migration rates that are rather close to DINP because their molecular weights and physical/chemical properties are close to each other and the water solubility of both are extremely low (DINP < 1 μg/l and DEHP?3μg/l). Source: Determination of Migration Rates for Certain Phthalates Survey of chemical substances in consumer products No. 149, 2016, Ministry of Environment and food of Denmark.

6.????Environment & health -

a.????DINP is more environment friendly than DOP.

b.????Its volatility, migration and non-toxicity are better than DOP, which can give good light resistance, heat resistance and aging resistance to the product.

c.?????DINP has lower density (0.972-0.98) and lower energy consumption with higher extrusion outputs compared to DOP (0.99 density of DOP)

d.????ECHA's?Risk Assessment Committee (RAC) has concluded, on March 7, 2018, that Di-isononyl phthalate (DINP) does not warrant classification for reprotoxic effects under the EU's Classification, Labelling and Packaging (CLP) regulation.

e.????The European Union has set a maximum specific migration limit (SML) from?food contact materials?of 9?mg/kg (9 ppm against 1000 ppm for DOP) for the sum of diisononyl phthalates and?diisodecyl phthalates.

7.????Processability -

DINP has good compatibility with PVC and will not precipitate even if it is used in large quantities.

DINP has superiority in improving extrusion efficiency.

Under typical extrusion processing conditions, DINP can reduce the melt viscosity of the compound more than DOP, which helps to reduce die pressure, reduce mechanical wear or increase extrusion productivity (up to 21%).

This increase in productivity can be realized without changing product formula and production process, without additional fixed investment, without additional energy consumption, and maintaining product quality.

8.????Identification of DINP (www.regulations.gov/, https://www.cpsc.gov/)

Unlike lower molecular weight phthalates, DINP is not composed of a single molecule.

Rather, it is produced by reaction of a phthalate moiety with alcohols. The majority of these alcohols have nine carbons (C9), but in various isomeric configurations. In addition, the alcohol fraction includes C8 and C10 alcohols.

Thus, commercial DINP is not simply phthalate molecules with two C9 arms, but a complex substance consisting of C8, C9 and C10 containing molecules. C9/C9 molecules predominant, but are not the only species.

Multiple CAS Registry Numbers are associated with DINP. However, there is no single generic CAS Registry Numbers that represents all DINP.

Some DINP products are further identified as DINP1, DINP2, or DINP3 based upon the manufacturing process used in their production.

DINP offers superior resistance to volatility, cost wise it is similar to cost of DOP, making it a frequently-selected effective and efficient alternative to DOP.