DPHP (Dipropylheptyl Phthalate): Properties, Uses in Plastics and Regulatory Status

DPHP (bis(2-propylheptyl) phthalate, CAS 53306-54-0) is a high molecular weight ortho-phthalate used as a low-volatility primary plasticizer for flexible PVC in cable, roofing and automotive compounds. Because its C10 alcohol makes it chemically close to DIDP, the first question buyers ask is how the two differ, and the answer is mostly regulatory rather than technical.

DPHP is registered under REACH, is not a Substance of Very High Concern, is not restricted under REACH Annex XVII entries 51 or 52, and is not listed in Annex I of Regulation (EU) No 10/2011 (status 22 September 2026). DPHP is one of 56 plasticizer pages in our directory of plastic additives, each carrying the same identity, dosage and regulatory fields.

This page covers DPHP's identity and chemistry, dosage in PVC, three named applications, performance against the substitution factors recorded for other plasticizers, a dated regulatory matrix, a safety profile that states plainly what is and is not confirmed, a comparison against DIDP, DINP, TOTM and the non-phthalate alternatives, and the producers whose pages list DPHP grades.

What Is DPHP (Di(2-propylheptyl) Phthalate)?#

DPHP is the bis(2-propylheptyl) diester of phthalic acid, a primary plasticizer that softens PVC on its own and takes its name from the C10 alcohol 2-propylheptanol used to make it. Phthalic acid forms the aromatic backbone common to every ortho-phthalate plasticizer; the two ester arms attached at the ortho position decide which specific phthalate results. By the ASTM D883 definition, a plasticizer is a substance incorporated into a plastic or elastomer to increase its flexibility, workability or distensibility.

Which alcohol separates DPHP from the other C10 phthalates? The alcohol used to esterify phthalic acid decides the product: a C4 alcohol gives DBP or DIBP, 2-ethylhexanol gives DEHP, a C9-rich isononanol gives DINP, a C10-rich branched-alcohol blend gives DIDP, and the single branched alcohol 2-propylheptanol gives DPHP. As a primary plasticizer, DPHP belongs to the largest additive family by weight; the hub on plasticizers for plastics compares all 14 classes.

What does DPHP stand for?#

DPHP stands for di(2-propylheptyl) phthalate, also written bis(2-propylheptyl) phthalate or dipropylheptyl phthalate, and in plastics it always means the single substance CAS 53306-54-0. Outside plastics the same four letters appear in other contexts, which the last section of this page separates.

Is DPHP a phthalate?#

Yes, DPHP is an ortho-phthalate, but it belongs to the high molecular weight group that EU restrictions do not cover: it is absent from REACH Annex XVII entries 51 and 52 and carries no harmonised CLP classification. European Plasticisers classifies phthalates by the backbone of the alcohol chain used to esterify them: low molecular weight (LMW) phthalates have 3 to 6 backbone carbons (DEHP is counted with this group because its 2-ethylhexanol backbone is C6), and high molecular weight (HMW) phthalates have 7 to 13 backbone carbons, a group that includes DINP, DIDP, DPHP, DIUP and DTDP. Being unrestricted is a legal status, not a hazard statement. DPHP is one of 14 phthalate plasticizers with a page in this directory, and one of the high molecular weight ones that EU restrictions do not cover.

Why do DPHP and DIDP share the formula C28H46O4?

DPHP and DIDP are C10 isomers: both have the formula C28H46O4 and a molecular weight of 446.7 g/mol, but DPHP is a defined substance made from a single alcohol, 2-propylheptanol, while DIDP is a UVCB mixture of C9 to C11 branched alcohols with more than 90% C10. That structural difference is why the two compounds are registered under REACH as separate substances even though a formula lookup alone cannot tell them apart. The difference shows up in regulation rather than in the formula: DIDP (diisodecyl phthalate) is restricted in mouthable toys under Annex XVII entry 52 and listed under Proposition 65, while DPHP is not restricted under either.

Why is DPHP called a high molecular weight phthalate?#

European Plasticisers defines high molecular weight phthalates as those with 7 to 13 carbon atoms in the backbone of the alcohol chain, a group that contains DINP, DIDP, DPHP, DIUP and DTDP. That group accounts for about 85% of Western European ortho-phthalate production, while low molecular weight phthalates are under 11%. DPHP sits toward the middle of the HMW carbon range, between the C9 alcohol of DINP and the C11 and C13 alcohols of DIUP and DTDP.

How Does DPHP Plasticize PVC?#

DPHP plasticizes PVC by placing its ester molecules between the polymer chains, weakening the dipole and van der Waals forces that hold them together and lowering the glass transition temperature. This solvation mechanism is common to every ortho-phthalate plasticizer; the ester carbonyl groups interact with the polar chlorine atoms on the PVC backbone, and the alkyl chains create free volume that lets the chains slide past each other.

What does the C10 chain change compared with a shorter-chain plasticizer? High molecular weight phthalates such as DPHP carry longer alkyl chains, and longer chains reduce volatility and improve permanence at the cost of some plasticizing efficiency. That is a class-level rule for the HMW group, not a measured DPHP value, because our source library holds no DPHP-specific volatility figure. Compatibility between a plasticizer and PVC is governed by the solubility-parameter difference between the two, which should stay within about ±1.5 (cal/cm3)^0.5 for a stable compound; below roughly 15 phr, antiplasticization can raise stiffness instead of lowering it.

The 4 classic plasticization theories are listed below.

• Lubricity theory: plasticizer molecules act as an internal lubricant, letting polymer chains slide past each other under stress.
• Gel theory: plasticizer molecules break the secondary bonding forces (van der Waals, dipole) that hold PVC chains in a rigid three-dimensional network.
• Free volume theory: plasticizer molecules increase the free space between chains, lowering the glass transition temperature and increasing chain mobility.
• Mechanistic (solvation-desolvation) theory: plasticizer molecules continuously solvate and desolvate polymer chain segments, combining aspects of the lubricity and gel theories.

The four theories and the solubility-parameter window are explained in full on how plasticizers work.

What Are the Physical and Chemical Properties of DPHP?#

DPHP is a high molecular weight ortho-phthalate ester with the formula C28H46O4 and a molecular weight of 446.7 g/mol, the same molecular weight as DIDP. Melting point, boiling point, relative density and flash point for DPHP are being verified against PubChem CID 92344 and are published once confirmed; this page does not repeat the unsourced "colourless viscous liquid" description that appears on producer and distributor pages, because it has not been checked against a primary physical-property source.

Note: melting point, boiling point, density and flash point are not yet confirmed in our source library and are not stated here.

Which Polymers Use DPHP, and at What Dosage?#

DPHP is used almost entirely in flexible PVC, at a typical level of 10 to 35 wt% of the plastic material according to ECHA's Plastic Additives Initiative mapping exercise. That band covers general-purpose to highly flexible compounds; the exact level a formulation needs depends on the target hardness, the polymer's own K-value and the rest of the recipe.

How does a wt% band convert to the phr figures a compound recipe uses? Compound recipes are built in parts per hundred resin (phr), and the conversion to weight percent uses the full formulation total: wt% = phr of DPHP divided by the total phr of the compound, multiplied by 100. A compound of 100 phr PVC, 35 phr DPHP and 5 phr heat stabilizer gives 35 / 140 x 100 = 25.0 wt% DPHP, lower than the phr figure alone suggests, because a real compound also carries stabilizers and fillers. Compound recipes give DPHP in PHR (parts per hundred resin), which converts to weight percent this way.

Plasticizer is only one line of the recipe; the full set of additives for PVC includes heat stabilizers, lubricants and fillers alongside the plasticizer package.

Footnote: 5 to 65 wt% is the total plasticizer content of flexible PVC across all plasticizers combined, not a DPHP-specific band.

DPHP in flexible PVC compounds#

DPHP sits in the general-purpose group of PVC plasticizers alongside DINP, DOTP and DINCH, and it is chosen where the compound has to keep its plasticizer through heat and weathering rather than where it has to gel fastest. Below about 15 phr, antiplasticization can raise the stiffness of the compound instead of lowering it, so formulators keep DPHP above that threshold once flexibility is the goal.

Compared with fast-fusing plasticizers, DPHP and the other general-purpose options gel more slowly, an inference drawn from the chain-length rule and the fast-fuser list rather than a measured DPHP gelation result; our source library holds no Shore A hardness value specific to DPHP. DPHP competes with DINP, DIDP, DOTP and DINCH across the plasticizers for PVC range, each offering a slightly different balance of cost, permanence and regulatory profile.

What Is DPHP Used For? 3 Applications in Plastics#

DPHP is used in 3 main plastics applications: cables and wires, roofing membranes and automotive parts.

• Cables and wires: PVC wire and cable insulation and jacketing compounds.
• Roofing membranes: single-ply PVC membranes for building and construction.
• Automotive parts: interior components specified against fogging limits.

Wire and cable insulation#

DPHP is one of 6 plasticizers used in PVC wire and cable compounds, together with DOTP, DINP, DIDP, TOTM and DTDP. Which plasticizer covers which temperature class is set out on plasticizers for wire and cable; this page does not assign DPHP to a specific temperature class, because no DPHP-specific rating is recorded in our source library.

PVC cable insulation is required to reach a minimum limiting oxygen index (LOI) of 26 vol% O2, a flammability requirement that sits alongside the plasticizer choice rather than depending on it alone. The full insulation package, including the stabilizer, flame retardant and filler chosen alongside the plasticizer, is set out on additives for wire and cable compounds.

Roofing membranes and construction#

PVC roofing membranes are the second named application for DPHP, because a membrane has to hold its plasticizer for decades of sun, heat and rain. Longer alkyl chains reduce volatility and improve permanence in the high molecular weight group generally, which is the class-level reason a HMW phthalate such as DPHP fits this application; no accelerated-weathering result for DPHP specifically is recorded in our source library, so this page states the requirement of the application rather than a measured DPHP property.

Membranes, profiles and pipes share a weathering problem, covered under additives for building and construction, where plasticizer permanence is one factor among the stabilizer and filler package.

Automotive interiors and low fogging#

Automotive interiors are the third named application for DPHP, where the requirement is low fogging: plasticizer that evaporates from a dashboard or door panel condenses on the inside of the windscreen. Low-volatility plasticizers such as TOTM, DIDP, DTDP and DUP are specified for this application, and DPHP's high molecular weight places it in the same low-volatility group. The plasticizers specified against fogging limits are compared on low-fogging plasticizers for automotive interiors.

Fogging performance for automotive interior compounds is measured with the DIN 75201 reflectometer or gravimetric method and the VDA 278 thermal desorption method; no DIN 75201 or VDA 278 result specific to DPHP is recorded in our source library, so this page names the test methods without quoting a value. DIN 75201 and VDA 278 are explained on fogging and VOC testing for automotive interiors.

How Does DPHP Perform in PVC?#

No substitution factor for DPHP is recorded in our source library: the published table we use covers DEHP (1.00, the reference), DOTP (1.03, typical), DINP (1.04, typical), DIDP (1.11, typical), TOTM (1.11, typical) and DTDP (1.26, typical), and DPHP is absent from it. What the chain-length rule establishes is the direction: a C10 ester is less volatile and more permanent than a C8 ester, and slightly less efficient, so a DPHP compound needs marginally more plasticizer than a DEHP compound for the same hardness. The substitution factors quoted for the other plasticizers come from one secondary source and are marked typical rather than exact.

The factors we do hold are listed on plasticizer efficiency and substitution factors, where DPHP is marked as not yet sourced. Standard tests exist for the indicators that matter: ASTM D1203 (Methods A and B) and ISO 176 measure volatility, ISO 177 measures migration, ASTM D1239 measures extraction resistance, and Shore hardness is measured to ISO 868 or ASTM D2240. ASTM D1203, ISO 177 and ASTM D1239 are explained on plasticizer migration.

Competitors publish "excellent heat resistance, low migration, low volatility" for DPHP with no numbers attached. This page instead prints the test methods and states plainly that the DPHP-specific values are not yet sourced, which is more useful than copied marketing adjectives.

How Does DPHP Combine with Other Plasticizers and Additives?#

High molecular weight plasticizers such as DPHP are usually blended rather than used alone: formulators add a fast fuser for gelation speed, an aliphatic diester for low-temperature flexibility and ESBO as a co-stabilizer.

• Fast fusers, used to speed gelation, include the legacy plasticizers DBP and BBP, the benzoates DPGDB and DEGDB, and TXIB.
• Aliphatic diesters, used for low-temperature flexibility, include DOA, DINA, DIDA, DOS and DOZ.
• Epoxidized plasticizers, ESBO (epoxidized soybean oil), act as a co-stabilizer at 1 to 2 wt% in plasticized PVC and, in a different dosage band, as a main plasticizer at 25 to 45 wt% (Czogała et al., 2021).

Every blend statement here is a class rule from the PVC formulation literature; no DPHP-specific blend ratio is recorded, so this section describes what formulators typically do, not a fixed recipe.

What Is the Regulatory Status of DPHP?#

DPHP is registered under REACH, is not a Substance of Very High Concern, is not restricted under REACH Annex XVII and is not authorised for food contact in either the EU or the United States (status 22 September 2026).

Entries 51 and 52, which list the restricted phthalates, are explained in full on REACH Annex XVII restrictions.

Is DPHP REACH registered, and is it an SVHC?#

Yes, DPHP is registered under REACH (Regulation (EC) No 1907/2006), and no, it is not a Substance of Very High Concern: it is absent from the Candidate List as of 22 September 2026. DEHP has been on the SVHC Candidate List since 28 October 2008, along with DBP and BBP; DIBP followed on 13 January 2010 and DCHP on 27 June 2018. DPHP has never been added. Our source library does not capture DPHP's REACH tonnage band.

Is DPHP allowed in food-contact plastics?#

No: DPHP is not listed in Annex I of Regulation (EU) No 10/2011, and because Annex I is a positive list, an additive absent from it may not be used in EU food-contact plastics. Annex I works as a positive list, which EU 10/2011 explains in full: only substances named in the annex, each with its own FCM number and migration limit where one applies, may be used in plastics intended to contact food. DIDP, by contrast, is listed as FCM substance 729 under group 26, with a group SML of 1.8 mg/kg since Regulation (EU) 2023/1442.

In the United States, DPHP is not among the 8 ortho-phthalates that FDA retained as authorised plasticizers in its final rule of 20 May 2022 (87 FR 31080). Which plasticizers are authorised and at what SML is tabulated on plasticizers in food contact materials.

Is DPHP allowed in toys and childcare articles?#

DPHP is not restricted in toys under EU REACH Annex XVII, US 16 CFR 1307 or Canada's SOR/2016-188, because none of these three rules lists it. Annex XVII entry 51 restricts DEHP, DBP, BBP and DIBP to ≤0.1 wt% in plasticised material of all articles, in force since 7 July 2020, and entry 52 restricts DINP, DIDP and DNOP to ≤0.1 wt% in mouthable toys and childcare articles; DPHP appears in neither entry. In the US, 16 CFR 1307 restricts DEHP, DBP and BBP permanently and DINP, DIBP, DPENP, DHEXP and DCHP since 25 April 2018, without listing DPHP. Canada's SOR/2016-188 lists DEHP, DBP, BBP, DINP, DIDP and DNOP, also without DPHP. The 8 phthalates restricted in US children's products are listed on CPSIA phthalate limits.

The EU Toy Safety Regulation (EU) 2025/2509 bans CMR substances and endocrine disruptors in toys from 1 August 2030. DPHP currently carries no harmonised CMR classification under CLP; this page does not predict how the rule will treat it.

Is DPHP listed under California Proposition 65?

Whether DPHP itself is listed under California Proposition 65 is not yet established on this page: our source library records no confirmed value for DPHP, and this has not been checked against the current OEHHA list, so no status is stated here. What is established is the listing history of DPHP's closest relatives: DIDP has been listed for developmental toxicity since 20 April 2007, and DINP for cancer since 20 December 2013, with a No Significant Risk Level of 146 µg/day. Listing dates for all plasticizers are on California Proposition 65.

Is DPHP Safe? Health, Safety and Environmental Profile#

DPHP has no harmonised hazard classification under the EU CLP Regulation, and all 188 companies that notified it to ECHA's classification and labelling inventory report that it does not meet the GHS hazard criteria. The high molecular weight phthalates as a group, DINP, DIDP, DPHP and DTDP among them, carry no harmonised reproductive-toxicity classification, in contrast to DEHP, DBP, BBP, DIBP and DCHP, which carry the Repr. 1B, H360 classification.

• Classification: no harmonised classification under CLP; classified "not classified" by 188 of 188 notifying companies in ECHA's C&L inventory.
• Group context: DPHP belongs to the high molecular weight phthalate group that carries no harmonised reproductive-toxicity classification, unlike the low molecular weight phthalates DEHP, DBP, BBP, DIBP and DCHP.
• What is not yet established on this page: our source library records a secondary summary stating that DPHP shows no reproductive or endocrine effects in rats, and that summary has not been verified against the ECHA registration dossier or a RAC opinion, so this page does not repeat it.

The restrictions summarised on phthalates: health effects apply to low molecular weight phthalates and do not transfer automatically to the high molecular weight group that DPHP belongs to.

What Are the Alternatives to DPHP?#

The 3 alternatives our substance directory records for DPHP are DIDP, DINP and TOTM, and the two non-phthalate routes formulators take instead are DOTP and DINCH. DEHP (DOP, dioctyl phthalate) is the substance this whole group replaced; it has been a Substance of Very High Concern since 28 October 2008 and requires REACH authorisation for continued use in the EU.

Full property data for the alternatives sit on the plasticizer comparison page.

DPHP vs DIDP#

DPHP is the better choice where the article can reach a child's mouth or where a Proposition 65 listing matters for the specific substance used, because DIDP is restricted in mouthable toys under REACH Annex XVII entry 52 and has been listed under Proposition 65 for developmental toxicity since 20 April 2007, while DPHP is not restricted under Annex XVII entry 52 and its own Proposition 65 status is not yet established on this page. DIDP is the choice where the part contacts food, because DIDP is authorised in the EU as FCM substance 729 and in the US as one of the 8 FDA-retained ortho-phthalates, and DPHP is authorised in neither.

This is a regulatory and supply-side verdict, not a performance one: our source library holds no comparative test data between the two, so no efficiency, migration or fogging difference is claimed. DIDP carries a typical substitution factor of 1.11 against the DEHP reference of 1.00; no equivalent figure exists for DPHP.

DPHP vs DINP#

DPHP and DINP are both high molecular weight ortho-phthalates, but DINP is the C9 general-purpose workhorse and DPHP is the C10 low-volatility grade: the extra carbon buys permanence and costs efficiency, following the chain-length rule that applies across the HMW group. DINP (CAS 28553-12-0, also 68515-48-0) has the formula C26H42O4, a molecular weight of 418.6 g/mol, and a typical substitution factor of 1.04; it is authorised in the EU up to a group specific migration limit of 1.8 mg/kg (FCM 728) and in the US under 21 CFR 178.3740 up to 43 wt% in vinyl chloride polymers.

The regulatory split is sharper than the chemical one: DINP (diisononyl phthalate) is restricted in mouthable toys in the EU under Annex XVII entry 52, restricted in US children's products under 16 CFR 1307 since 25 April 2018, and listed under Proposition 65 for cancer since 20 December 2013, while DPHP is on none of those lists. DINP is, however, authorised for food contact and DPHP is not.

DPHP vs TOTM#

TOTM is the step above DPHP in permanence: it is a trimellitate with three ester arms and a molecular weight of 546.8 g/mol, which gives a lower vapour pressure than any C10 phthalate, at a typical substitution factor of 1.11. TOTM (CAS 3319-31-1) is specified for high-temperature wire and cable and low-fogging automotive interiors, the same two applications named for DPHP, but at a higher permanence tier. In one study, Kaya et al. (2026, Polymers) recorded a decomposition onset of 262 °C for TOTM at 50 phr in a PVC cable compound, the highest thermal resistance among the plasticizers tested; that figure describes TOTM, not DPHP, and no equivalent onset or UL temperature rating exists for DPHP.

TOTM (trioctyl trimellitate) is the standard where permanence matters more than cost.

DPHP vs DOTP and other non-phthalates#

The reason a formulator leaves DPHP for DOTP or DINCH is rarely performance and almost always a specification: a customer requirement for phthalate-free material rules out every ortho-phthalate, including the unrestricted ones. DOTP / DEHT (dioctyl terephthalate) is the para isomer that regulators do not treat as an ortho-phthalate: it carries CAS 6422-86-2, is authorised in the EU as FCM substance 798 with an SML of 60 mg/kg, and has a typical substitution factor of 1.03.

DINCH (CAS 166412-78-8, US product CAS 474919-59-0) is a hydrogenated version of DINP, with a molecular weight of 424.7 g/mol, authorised in the EU as FCM substance 775, and used in medical devices, toys and food contact. A phthalate-free specification points the formulator to non-phthalate plasticizers; this page does not claim that DOTP or DINCH is safer than DPHP, only that each carries a different classification.

Who Manufactures DPHP? Grades and Suppliers#

DPHP is produced by several global plasticizer makers: BASF sells it as Palatinol DPHP, Nan Ya Plastics lists it among its phthalate plasticizers, and The Chemical Company supplies it as ChemFlexx DPHP (producer product pages checked 22 September 2026). Univar Solutions distributes Palatinol DPHP. These names come from the producers' own product pages, not from a certified grade registry, and are recorded with the check date rather than as a verified manufacturer list.

More producers and their locations are in the directory of plasticizer manufacturers. Feedstock and freight drivers for the phthalate range are tracked on plasticizer prices. Buyers should request the supplier's TDS and SDS and a written statement of the food-contact and toy-restriction status for the destination market before ordering.

Request quotes for DPHP from verified suppliers: grade, volume, country, delivery date. Get quotes via the plastic additive supplier finder or request a DPHP sample directly. Send one request to several DPHP suppliers with the plastic additive supplier finder.

─── ⁂ ───

Where Does DPHP Sit Among High Molecular Weight Phthalates?#

DPHP is the defined-substance C10 member of the high molecular weight phthalate group, the family that supplies about 85% of Western European ortho-phthalate production alongside DINP, DIDP, DIUP and DTDP. Global plasticizer consumption runs to 8.4 Mt/yr (European Plasticisers), and more than 85% of European plasticizer use goes into flexible PVC. The whole group is compared on the page for high molecular weight phthalates and their low molecular weight counterparts.

DUP/DIUP and DTDP: the higher-MW cable plasticizers#

Above DPHP sit two longer-chain phthalates: DUP/DIUP at C11 and 474.7 g/mol, and DTDP at C13 and 530.8 g/mol, the highest molecular weight phthalate in commercial use. DUP/DIUP (diundecyl phthalate), CAS 3648-20-2 (linear) and 85507-79-5 (branched), is a low-volatility plasticizer for wire, cable and automotive use, not listed in EU 10/2011 Annex I and not an SVHC as of the 22 September 2026 check of ECHA CHEM.

DTDP (ditridecyl phthalate), CAS 119-06-2, is the highest-MW phthalate in this comparison, used in high-temperature automotive wire, also absent from EU 10/2011 Annex I, and carrying a typical substitution factor of 1.26 against the DEHP reference.

DPHP or DPhP? Two abbreviations that look alike#

In plastics, DPHP always means di(2-propylheptyl) phthalate, CAS 53306-54-0, and the safest way to confirm a data sheet is to match that CAS number rather than the four letters. Searches for "DPHP" also return results from cosmetics and from toxicology papers that use a similar-looking abbreviation for a different substance; this page does not name that other substance or its CAS number until the identification has been verified against a primary source, so it flags the collision without stating a cross-reference as fact.

Is DPHP banned anywhere?

No: DPHP is not banned or restricted under the EU, US or Canadian rules covered on this page, although it is not authorised for food-contact plastics in either the EU or the US (status 22 September 2026). It is absent from the REACH Candidate List, from Annex XVII entries 51 and 52, from 16 CFR 1307, and from Canada's SOR/2016-188. Country rules are compared on phthalate restrictions worldwide.

Can DPHP replace DIDP one-to-one?

Probably close, but our source library holds no substitution factor for DPHP, so this page gives no conversion figure: DIDP's typical factor is 1.11 against DEHP's reference of 1.00, and a DPHP trial has to be run against the compound's own hardness target. Run the comparison for the plasticizers this directory does hold factors for in the plasticizer substitution calculator.

Does DPHP have an HS code and a price?

No HS code and no price figure for DPHP is held in our source library, so this page quotes neither; DPHP prices track the same feedstock and freight drivers as the other phthalate plasticizers. Current drivers are tracked on plasticizer prices.