A plasticizer is chosen on four things: compatibility with the resin, permanence (resistance to migration, extraction and volatile loss), low-temperature flexibility, and regulatory acceptability in the market the finished article is sold into. On that basis: DOP remains the industry reference point against which every other plasticizer is benchmarked, DOTP is its principal non-ortho-phthalate replacement, and chlorinated paraffin wax is a secondary plasticizer used alongside a primary — never instead of one.
We supply all six materials discussed here from Chennai. This guide is written for the compounder deciding between them, not for the person who has already decided.
Reviewed 13 August 2026.
Comparison table — six plasticizers side by side
| Trade name | Chemical name | CAS | Primary or secondary | Typical role | Notable property | Regulatory note |
|---|---|---|---|---|---|---|
| DOP / DEHP | Bis(2-ethylhexyl) phthalate | 117-81-7 | Primary | General-purpose flexible PVC | Molecular weight 390.56; the benchmark for efficiency, permanence and cost | Ortho-phthalate; restricted in specific article categories in the EU and US |
| DOTP / DEHT | Bis(2-ethylhexyl) terephthalate | 6422-86-2 | Primary | General-purpose flexible PVC, non-ortho-phthalate specifications | Same molecular formula and weight as DOP (C24H38O4, 390.56) — the para isomer | Not an ortho-phthalate; outside the EU ortho-phthalate restriction and authorisation entries |
| DBP | Dibutyl phthalate | 84-74-2 | Primary (specialty) | Fast-fusing plasticizer for adhesives, inks, cellulose esters | Molecular weight 278.35 — lower MW means faster fusion and higher volatility | Ortho-phthalate; on the EU REACH Annex XIV authorisation list |
| DEP | Diethyl phthalate | 84-66-2 | Specialty — cellulose esters and non-durable PVC | Cellulose ester plasticizer, PVC and flexible plastic compounding, fragrance fixative, alcohol denaturant | Molecular weight 222.24 — the most volatile of the group; odourless, low colour | Ortho-phthalate; not covered by the EU toy/childcare entry that names DEHP, DBP, BBP and DIBP |
| DOM | Bis(2-ethylhexyl) maleate | 142-16-5 | Specialty plasticizer / co-plasticizer | Low-colour, low-acid plasticizer and reactive comonomer | Molecular weight 340.50; retains a C=C double bond, so it can copolymerise | Maleate ester, not a phthalate |
| CPW-52 | Chlorinated paraffins (~52% Cl) | 63449-39-8 | Secondary | Cost extender and flame retardant in flexible PVC | Adds flame retardance that none of the ester plasticizers here provides | Short-chain chlorinated paraffins (C10–13) are listed under Annex A of the Stockholm Convention; confirm chain length with the producer |
The CAS numbers above are the ones we publish on each product page. Quote the CAS number on every purchase order — "DOP" and "DOTP" are one letter apart in an email and four decades apart in regulatory treatment. Molecular weights are calculated from the published molecular formulae. Any other physical figure should come off the producer's datasheet and the batch Certificate of Analysis, which is why we have not filled this table with viscosities and pour points.
Primary vs secondary plasticizer — what the distinction means in the mix
A primary plasticizer is compatible with PVC across the full useful loading range. It solvates the resin, carries gelation and fusion, and can be used on its own. DOP and DOTP are primary plasticizers. DOM is a specialty ester used as a plasticizer and comonomer, not a general-purpose primary.
A secondary plasticizer has limited compatibility with PVC. It cannot solvate the resin by itself and will exude if overloaded. It is added alongside a primary to cut cost, add flame retardancy or modify a specific property, while the primary does the gelation work. CPW is the secondary plasticizer used in almost every Indian flexible PVC formulation.
Chlorine content is the axis that governs how much CPW a formulation will take. The CPW-52 grade — roughly 52% chlorine — is the workhorse for PVC and cable compounds in India, and typically replaces 20–40% of the plasticizer load. Push it further and low-temperature flexibility deteriorates and exudation risk rises. Our CPW-52 grade guide covers the 42 / 52 / 70 grade system and the specification values that matter on incoming inspection.
DOP vs DOTP — the substitution question
DOTP is the terephthalate isomer of DOP. Both are bis(2-ethylhexyl) esters with the molecular formula C24H38O4 and a molecular weight of 390.56. The difference is where the two ester groups sit on the benzene ring: ortho (adjacent, 1,2) in DOP, para (opposite, 1,4) in DOTP. Because DOTP is not an ortho-phthalate, it falls outside the regulatory instruments written specifically against ortho-phthalates, while plasticizing PVC in broadly the same way and at broadly the same loading.
Performance in flexible PVC is comparable, subject to a fusion and loading check on a trial batch. Where it is not a straight drop-in:
- Fusion behaviour. Compounders consistently report that DOTP is slower-fusing than DOP and needs a somewhat higher fusion temperature or longer dwell to reach the same gelation. On a dry-blend or plastisol line running close to its thermal limit, this is a process change, not a substitution.
- Loading adjustment. DOTP is marginally less efficient than DOP in most compounds, so a small upward adjustment in phr is common to hold the same hardness. Validate on your own recipe rather than assuming parity.
- Stabiliser and lubricant package. A recipe re-tuned for a slower-fusing plasticizer often needs its lubricant balance revisited to avoid plate-out.
Where it is close to a drop-in: general flexible PVC where the compound is not thermally constrained, and hardness is re-checked on a trial batch.
Regulatory direction, stated carefully
The instruments driving substitution are specific and worth naming precisely, because most of the commentary around them is not. Under EU REACH, DEHP (DOP), DBP, BBP and DIBP are on the Annex XIV authorisation list, meaning their use in the EU requires authorisation. Annex XVII entry 51 restricts those same four ortho-phthalates in toys and childcare articles and, since July 2020, in plasticised material in a wider set of articles. In the United States, CPSIA section 108 permanently prohibits DEHP, DBP and BBP above 0.1% in children's toys and child care articles, and the CPSC's 2017 final rule extended the prohibition to DINP, DIBP, DPENP, DHEXP and DCHP. In India, toys are covered by the Toys (Quality Control) Order, 2020, which mandates conformity to the IS 9873 series.
These are the current texts as we understand them; they are amended, and none of this is legal advice. The practical point for an Indian compounder is simpler: if you supply into an export chain, the phthalate question will reach you through your customer's specification long before it reaches you through Indian law. Confirm the applicable requirement with your customer and, where the market is regulated, with the current instrument text.
Where DBP and DEP still belong
DBP is not a general-purpose PVC plasticizer in the way DOP is, and treating it as a cheaper DOP is a mistake. At molecular weight 278.35 it is a low-molecular-weight, fast-fusing ester: it solvates quickly and builds viscosity fast, which is exactly what you want in an adhesive, a sealant or a printing ink. The same low molecular weight makes it more volatile and less permanent than DOP, so it is a poor choice anywhere the article must hold flexibility over years of service at temperature. Its enduring uses are nitrocellulose and cellulose acetate lacquers, adhesives and sealants, printing inks, and as a fusion aid in plastisols.
DEP is a specialty ester that sits largely outside durable PVC. At molecular weight 222.24 it is the most volatile ester of this group, and it is valued for being low in colour and effectively odourless — our DEP is specified as an odourless liquid at 30 APHA maximum. It is used in PVC compounding and flexible plastic processing, as a plasticizer for cellulose esters and film-forming polymers, as a fixative in fragrance compounding, and as a denaturant in specially denatured alcohol. Its volatility is what rules it out of durable goods, not any incompatibility with PVC.
DOM and the low-temperature problem
When low-temperature flexibility is the governing requirement, the conventional primary plasticizers are the adipate and sebacate esters — DOA and DOS and their relatives. We do not carry an adipate or a sebacate. DOM — bis(2-ethylhexyl) maleate, CAS 142-16-5 — is the low-temperature-oriented ester we do carry, and it earns its place where its low colour, low acid value or copolymerisable double bond is wanted alongside cold flexibility, rather than as the category's default answer. It is a maleate ester of the same 2-ethylhexyl alcohol used to make DOP, supplied in Plasticizer Grade (Industrial) at 99.0% mass minimum ester content and 100 Hazen maximum colour.
Its second, less obvious use follows from its structure. Unlike a phthalate, DOM retains a carbon-carbon double bond from maleic anhydride, so it can be copolymerised into an emulsion polymer backbone as an internal plasticizer rather than sitting in the compound as a free additive. An internally plasticized polymer cannot lose its plasticizer to migration or extraction. That property is why we list adhesive and coating emulsions, and use as a comonomer in emulsion polymer systems, among DOM's applications.
Selection by application
| Application | First choice | Secondary / co-additive | Reason |
|---|---|---|---|
| Flexible cable and wire compound | DOP, or DOTP where the specification excludes ortho-phthalates | CPW-52 | CPW adds flame retardance and cuts cost while the primary carries gelation |
| PVC flooring and sheeting | DOP or DOTP | CPW-52 | General-purpose efficiency with cost extension; DOTP where export specs demand it |
| Hoses and extruded profiles | DOP or DOTP | CPW-52 | Permanence over long service life; low volatile loss matters more than fusion speed |
| Artificial leather / leather cloth | DOP or DOTP | CPW-52 | Hand and drape are set by primary loading; CPW controls cost and flame behaviour |
| Plastisol coating and dipping | DOP or DOTP | DBP as fusion aid | DBP accelerates fusion; watch paste viscosity ageing and volatility |
| Low-temperature flexible goods | Adipate or sebacate ester conventionally; DOM among the esters we carry | — | Cold flexibility governs over cost; DOM suits where low colour, low acid value or a copolymerisable double bond is also wanted |
| Adhesives and sealants | DBP | DOM in emulsion systems | Fast solvation and viscosity build; DOM where a non-migrating internal plasticizer is wanted |
| Printing inks and NC lacquers | DBP | DEP | Compatibility with nitrocellulose and cellulose esters; DEP where colour and odour are critical |
What to specify on an enquiry and what a CoA should show
Plasticizer quality complaints in the field very rarely trace to assay. They trace to acid value and colour. A high acid value signals incomplete esterification or hydrolysis in storage, and it attacks the stabiliser package, showing up as early discolouration during processing. High colour shows up directly in light-coloured and transparent end products, where nothing downstream can rescue it. Check both on every lot.
On the plasticizer CoA — tested on the neat ester
| Parameter | Why it matters | Common test reference |
|---|---|---|
| Ester content / assay | Confirms the material is what the label says | ASTM D1045; ester content by GC |
| Acid value (mg KOH/g) | Leading cause of processing discolouration and stabiliser consumption | ASTM D1045 |
| Colour (APHA / Pt-Co) | Carries straight through into light and transparent articles | ASTM D1209 |
| Water content | Causes voids and foaming in fusion; promotes hydrolysis | Karl Fischer, ASTM E203 |
| Specific gravity | Volumetric dosing accuracy and identity confirmation | ASTM D1045 |
Verified on the compound, not on the drum
These three are properties of the finished plasticized compound, not of the neat ester. Do not expect them on a plasticizer CoA — run them on your own trial compound.
| Parameter | Why it matters | Common test reference |
|---|---|---|
| Volatility / volatile loss | Predicts permanence and fogging in service | ASTM D1203 (activated carbon method, on sheeting specimens) |
| Low-temperature stiffness | Governs cold-flex behaviour in the finished compound | ASTM D1043 (Clash-Berg torsional stiffness) |
| Brittleness temperature | Sets the practical cold service limit of the article | ASTM D746 (brittleness temperature by impact) |
On an enquiry, tell us: the material and CAS number, the grade, the packaging you can receive (drums or bulk tanker), your delivery location, and — most usefully — the application. The application is what lets us flag a mismatch before a drum ships. Indicative grades we carry: DOP at 99.50% minimum ester content, DOTP at 99.50% minimum plasticizing ester by GC, DBP at 99.50% minimum plasticizing ester by GC, DEP Industrial Grade at 99.00% minimum, DOM Plasticizer Grade (Industrial) at 99.0% mass minimum ester content, and CPW at approximately 52% chlorine. Every consignment carries the producer's batch Certificate of Analysis; TDS and SDS download from each product page.
Storage, handling and shelf considerations
Ester plasticizers are high-boiling, high-flash-point liquids — combustible rather than flammable — but the specific flash point differs by material and should be read off that product's SDS, not assumed from a neighbouring one. Practical points:
- Keep drums closed and out of direct sun. Moisture pickup drives hydrolysis, which raises acid value on a material that met specification on arrival.
- Store away from strong oxidising agents. Incompatibility with oxidisers is stated in section 10 of the SDS for these esters; segregate accordingly in the store.
- Check elastomer compatibility before you plumb a transfer line. Plasticizer esters swell and degrade many common elastomers. PTFE and fluoroelastomer seals are the usual specification for ester service; confirm against the gasket manufacturer's chemical resistance chart for the specific ester.
- Cold weather and viscosity. CPW-52 is a viscous liquid and pumps slowly in cool conditions; allow for it in unloading time rather than heating aggressively.
- Dedicate pumps and lines where colour matters. Cross-contamination between a high-colour and a low-colour ester is a common and entirely avoidable rejection.
FAQ
What is the difference between DOP and DOTP?
They are isomers with the same molecular formula, C24H38O4, and the same molecular weight, 390.56. DOP (CAS 117-81-7) is the ortho-phthalate ester; DOTP (CAS 6422-86-2) is the terephthalate, or para, ester. DOTP plasticizes PVC similarly but sits outside the regulations written against ortho-phthalates, and generally fuses more slowly than DOP.
Is DOTP a phthalate?
DOTP is an ester of terephthalic acid, not of ortho-phthalic acid, so it is not an ortho-phthalate and is marketed as a non-phthalate or phthalate-free plasticizer. That is why it is not named in the EU REACH Annex XIV authorisation entries or the Annex XVII entry 51 restriction, which list DEHP, DBP, BBP and DIBP.
Can chlorinated paraffin wax replace DOP?
Not entirely. CPW is a secondary plasticizer with limited compatibility with PVC. It typically replaces 20–40% of the plasticizer load, cutting cost and adding flame retardance while a primary such as DOP or DOTP carries gelation. Replacing the primary outright degrades low-temperature flexibility and risks exudation.
What is DBP used for?
DBP (CAS 84-74-2) is a fast-fusing, low-molecular-weight plasticizer used in nitrocellulose and cellulose acetate lacquers, adhesives and sealants, printing inks, and as a plastisol fusion aid. Its molecular weight of 278.35 makes it more volatile and less permanent than DOP, so it is not a general-purpose plasticizer for durable flexible PVC.
Which plasticizer is used in PVC cable?
Flexible PVC cable compound is normally built on a general-purpose primary plasticizer — DOP, or DOTP where the specification excludes ortho-phthalates — combined with CPW-52 as a secondary plasticizer, which reduces cost and contributes flame retardance. The exact ratio is set by the required hardness, cold-flex temperature and flame rating.
Sourcing all six from one supplier
We supply DOP, DOTP, DBP, DEP, DOM and CPW from Chennai, with dispatch across South India, and have direct import capability for materials not produced locally. Because we carry the whole family, a trial substitution does not mean opening a new vendor. Our earlier DOP sourcing and PVC processing guide covers grades and packaging for DOP specifically; this post is the selection guide across the family. Share your application and current formulation position with Sanketh on +91 86087 80096 (WhatsApp) or admin@supremepetrochemicals.com, or use the contact page. Quotes are typically answered within 4 working hours, Monday to Saturday.
Product pages with TDS and SDS downloads: DOP, DOTP, DBP, DEP, DOM, CPW.