PVC plasticizers sort into five working families: ortho-phthalates, non-phthalate monomeric esters, polymeric plasticizers, bio-based plasticizers, and the secondary or specialty grades that extend or modify a primary. The labels overlap — ATBC is both non-phthalate and bio-based — because each answers a different question: the acid the ester is built on, whether it is restricted, how large the molecule is, and whether it can carry a compound alone.
Phthalate Plasticizers
Ortho-phthalates — diesters of phthalic anhydride with alcohols from butanol up to isodecanol — are still the reference general-purpose plasticizers for PVC, but the family now divides by regulatory status rather than performance. DEHP (DOP), DBP, BBP and DIBP are restricted in most markets; the higher-molecular-weight DINP, DIDP and DPHP stay usable outside toys and childcare articles; and where neither the EU nor the US regime applies, DOP remains the cost benchmark.
Performance follows the alcohol chain. Short chains (DBP, DIBP) fuse fastest and plasticize most efficiently but are volatile and migrate readily; DOP is the mid-point every other plasticizer is measured against; DINP, DIDP and DPHP give up a little efficiency for lower volatility, better heat ageing and lower migration. The same trade-off runs through every family below: molecular weight buys permanence and costs efficiency and fusion speed.
| Phthalate | EU — REACH Annex XVII | US — CPSC 16 CFR 1307, children’s toys and child-care articles |
|---|---|---|
| DEHP (DOP) | Entry 51: barred at or above 0.1% by weight of the plasticised material in articles generally, since 7 July 2020 | Listed: 0.1% (1000 ppm) in any accessible plasticised component |
| DBP | Entry 51, as DEHP | Listed |
| BBP | Entry 51, as DEHP | Listed |
| DIBP | Entry 51, as DEHP | Listed |
| DINP | Entry 52: above 0.1% barred only in toys and childcare articles that can be placed in the mouth | Listed — in all children’s toys and child-care articles, mouthable or not |
| DIDP | Entry 52, as DINP | Not listed |
| DPHP | Not named in entry 51 or 52 | Not listed |
The line between the two groups is classification. DEHP, DBP, BBP and DIBP are Repr. 1B — hence the entry 51 article restriction. “Plasticised material” in that entry covers the coatings, inks, adhesives and decals on an article as well as the PVC, so a phthalate-free compound carrying a DOP-plasticised print is still a failing article. Exclusively industrial, agricultural or outdoor uses without prolonged skin contact are exempt.
Food contact is the other boundary. Phthalates remain authorised under Regulation (EU) 10/2011, but the 2023 amendment cut the DEHP migration limit to 0.6 mg/kg and the combined DINP + DIDP limit to 1.8 mg/kg — tight enough that new food-contact compounds are built on the non-phthalates below rather than qualified against those numbers.
Non-Phthalate Plasticizers
Non-phthalate plasticizers are monomeric esters built on an acid other than ortho-phthalic — terephthalic (DOTP), cyclohexane-dicarboxylic (DINCH, DEHCH), trimellitic (TOTM, TINTM), adipic (DOA, DINA) and citric (ATBC) — and between them they cover the phthalate performance range, with DOTP the nearest drop-in for DOP. None is named in REACH entries 51 or 52 or in the CPSC list of eight, which is what a phthalate-free line on a spec sheet is asking for.
| Family — grades | What it buys | What it costs |
|---|---|---|
| Terephthalates — DOTP (DEHT) | Efficiency close to DOP, lower volatility, same handling on an existing line | Slower fusion: plastisols and calendered sheet need a higher gelation temperature or a fast-fusing co-plasticizer |
| Cyclohexanoates — DINCH, DEHCH | Low migration, low plastisol viscosity, established food-contact and medical use | Less efficient than DOP; higher price |
| Trimellitates — TOTM, TINTM | Very low volatility: heat-aged cable, automotive interiors with a fogging limit, medical tubing | Slowest fusion in the group, low efficiency, highest price |
| Adipates — DOA, DINA | Best low-temperature flexibility | Volatile and extractable; run as a blend partner, rarely alone |
| Citrates — ATBC | Fast fusion; accepted in food, medical and toy work | Volatile and extractable; price (see bio-based below) |
Non-phthalate does not mean unregulated; each ester has its own food-contact entry. DOTP (FCM 798), DINCH (FCM 775) and ATBC (FCM 138) are authorised under Regulation (EU) 10/2011 with their own migration limits, so a declaration of compliance still needs a migration result against the current Annex I value.
TOTM rests on EFSA’s 2019 assessment instead: no consumer concern in soft PVC at up to roughly 10% in wrap film and 40% in tubing, provided migration stays at or below 5 mg/kg.
Medical PVC moved from DOP to TOTM, DINCH and DEHCH for a regulatory reason as much as a migration one. The Medical Device Regulation caps CMR 1A/1B and endocrine-disrupting substances at 0.1% w/w in invasive devices and in anything that stores or administers medicines or body fluids unless the use is justified; DEHP’s Repr. 1B classification puts it inside that trigger, and the non-phthalates without a CMR classification sit outside it.
Polymeric Plasticizers
Polymeric plasticizers are polyester chains — adipic, sebacic or azelaic acid condensed with a glycol and end-capped — large enough that they barely leave the PVC matrix; the working criterion in a 2021 review of low-migration PVC plasticizers is an average molecular weight above 2,000 g/mol. Specify them when migration or extraction, not cost or line speed, is the failure mode.
A chain that size diffuses through the matrix far more slowly than a monomeric ester and does not partition into what the part touches — fats and oils, fuels, polystyrene insulation, nitrocellulose lacquer, a neighbouring plasticised part. That is why they sit in waterproofing membranes laid against polystyrene insulation or bitumen, fuel and oil hose, and automotive trim with a fogging limit; volatility is negligible for the same reason.
The price is paid on the line. Viscosity is the usual difficulty: a polymeric plasticizer absorbs slowly in dry blend, raises plastisol viscosity, fuses slowly and plasticizes less efficiently, so the compound needs more of it for the same hardness and loses low-temperature flexibility. Most formulations therefore blend a polymeric with a monomeric ester — enough polymeric to hold the migration spec, enough monomeric to keep the line running.
Bio-Based Plasticizers
Bio-based plasticizers are esters whose carbon comes wholly or partly from renewable feedstock — epoxidised vegetable oils (ESBO, epoxidised linseed oil) and citrates (ATBC) in commercial volume, with epoxidised fatty-acid esters and bio-derived succinates behind them. Two things the label does not tell you: what dose actually plasticizes, and how much of the molecule is renewable.
ESBO is the case where dose changes what the additive is. At the 1–2 wt% most compounds carry, it is a co-stabiliser: the oxirane rings scavenge the HCl that PVC releases on heating. Any softening at that level is incidental.
Genuine plasticization with ESBO takes 25–45 wt%, and at that loading its limited compatibility shows up as exudation, so it runs as a partial replacement in a blend rather than as a sole plasticizer. On the CoA, oxirane oxygen content is the number that predicts stabiliser performance. ESBO is FCM 532 under Regulation (EU) 10/2011, which is why fatty-food wrap film and closure gaskets carry it.
ATBC is the bio-based grade that behaves as a true primary: fast fusion, good efficiency, and acceptance in food-contact (FCM 138), medical and toy work. Its costs are volatility, extraction by fats and alcohols, and price, which keep it in thin-wall and high-value parts — cling film, tubing, toys — rather than general-purpose compound.
“Bio-based” is a feedstock claim, and the test for it is radiocarbon content by ASTM D6866. An ester whose acid is renewable but whose alcohol is petrochemical carries only the acid’s share of biogenic carbon, so ask for the D6866 result, not the adjective. Bio-based is also a separate claim from biodegradable and from low-migration: ATBC is more extractable than DINCH whatever its feedstock.
Secondary / Specialty Plasticizers
Secondary plasticizers are extenders — chlorinated paraffins above all — that PVC will not accept at full loading on their own but that replace part of a primary ester at lower cost. Specialty plasticizers are primaries or co-plasticizers chosen for one property the general-purpose esters lack: flame retardancy from phosphate esters, fast fusion and plastisol viscosity control from benzoates and TXIB.
Chlorinated paraffins extend the primary, add flame retardancy through their chlorine and improve oil resistance, and their limit was always compatibility — exudation once the primary’s share drops too far. The limit now is regulatory. Short-chain grades (C10–13, SCCPs) have been on the Stockholm Convention’s Annex A since 2017, and the EU POPs Regulation tolerates them only below 1% in mixtures and 0.15% in articles.
Medium-chain grades (C14–17, MCCPs), the ones most compounders actually used, were added to Annex A at COP-12 in May 2025. The matching EU restriction — a 0.1% limit with time-limited exemptions — was proposed in late 2025 and had not been confirmed as adopted at the time of writing. A compound still built on an MCCP extender needs a replacement plan now, not when the entry lands.
Phosphate-ester plasticizers are the route to flame-retardant flexible PVC without loading it with mineral filler. Triaryl phosphates such as TXP plasticize nearly as well as a phthalate and carry the flame retardancy in the same molecule; chloroalkyl phosphates such as TCPP and TCEP are stronger retardants and weaker plasticizers, so they are dosed as co-plasticizers alongside a primary ester.
Toys exclude the chloroalkyls outright: Directive 2009/48/EC Appendix C caps TCEP, TCPP and TDCP at 5 mg/kg each in toys for children under 36 months or meant to be mouthed, and Regulation (EU) 2025/2509 extends those limits to all toys from 1 August 2030. TCEP also drew an unreasonable-risk finding from the US EPA in September 2024, so treat it as a legacy grade; outside toys, qualify TCPP or an aryl phosphate instead.
Fast-fusing specialties — dibenzoates and TXIB — lower the gelation temperature and cut plastisol viscosity, which is what lets a DOTP or DINCH plastisol run on a DOP cycle. They are volatile, so they are dosed as a fraction of the plasticizer package rather than as its base.
Conclusion
Pick the family from the constraint that will fail first.
- No regulatory constraint: DINP, DPHP or DOTP give DOP-level performance at lower volatility.
- Toy, food-contact or medical spec: DOTP, DINCH, ATBC or TOTM, each checked against its own migration limit.
- Migration or extraction failure in service: a polymeric plasticizer, blended with a monomeric ester to keep the line running.
- Bio-based claim: ESBO or ATBC, with an ASTM D6866 result behind the label.
- Cost-down target: the chlorinated-paraffin route is closing under the Stockholm Convention, so the saving has to come from the primary — DINP or DPHP where they are permitted — not from an extender.
Within the family, the grade — and the phr that hits a Shore A target on your resin and stabiliser package — is a ladder trial, not a table. That is the next decision, and the CoA numbers for volatility, migration and efficiency are what decide it.