The skin material gets argued at the polymer. The carmaker’s own interior specification usually settled it before the argument started.
Continental produces instrument-panel cover materials in PVC, PUR and TPO to manufacturer specifications. ILPEA runs PVC and polyolefin slush surfaces as parallel options for the same dashboards. Neither states a preference.
Three specification lines decide the skin: a restricted-ester line, an interior emission and fogging limit, and an end-of-life recyclate commitment. Only the third is about the polymer. The first two are about the compound and the finished part.
How Slush Moulding Narrows the TPO vs PVC Skin Choice
PVC powder is amorphous, and that amorphous structure delivers the flowability that translates into sharp edges, deep undercuts and fine grain retention on an instrument-panel skin.
Polyolefin powder requires cryogenic pulverization, which creates particle defects that produce poor flowability and higher scrap rates (Dow, US 9,505,868 B2; US 2022/0127447 A1). The skin also needs a flame or plasma surface treatment for polyurethane foam adhesion, and the effectiveness of that treatment is limited by part geometry (US 2022/0127447 A1).
Cost per finished part at equivalent grain and soft touch is the honest comparison. PVC’s established slush tooling, cleaner powder flow and direct foam bond keep its total cost lower. The polyolefin skin pays back part of its mass saving on the surface treatment, the powder processing and the scrap at deep draws.
What a Phthalate Clause in an OEM Interior Specification Actually Restricts
REACH Annex XVII entry 51 names four ortho-phthalates (DEHP, DBP, BBP, DIBP) at 0.1% by weight of the plasticised material. No terephthalate, trimellitate, adipate or cyclohexanedicarboxylate appears in the entry.
Entry 51 defines “plasticised material” to include PVC, PVDC, PVA, polyurethanes, “any other polymer”, and surface coatings, finishes, adhesives, paints and inks. A polyolefin skin and its coating sit inside the same scope. The restriction is not a PVC rule.
The automotive derogation in paragraph 4(c) covers motor vehicles placed on the market before 7 January 2024. A program starting now sits inside the restriction.
GADSL, the industry’s declarable-substance framework, reinforces the same structure. Declaration thresholds apply at 0.1% by weight of homogeneous materials.
The “Phthalates, selected” entry covers a limited list. The GADSL guidance states that declaration “does not mean, however, that the substance is prohibited from being used in vehicle parts or is to be de-selected from use.”
A program that reads a phthalate clause as ruling out PVC has answered a question the specification did not ask. The restricted-ester line restricts esters at the compound level, and a PVC skin reformulated with DOTP or DINCH answers that line. The compound’s heat resistance at the instrument-panel thermal tier determines whether it also clears the fogging and ageing gates.
Why Interior Fogging Is a Compound Question, Not a Polymer Choice
Plasticizer migration and volatilization over time cause fogging of the windshield glass and physical property changes in the PVC skin (Dow, US 9,505,868 B2). The mechanism is real.
A polyolefin skin carries no plasticizer. The fogging objection does not arise, and that is a genuine advantage.
Whether fogging rules out PVC depends on the ester the compound carries. Trimellitates at the instrument-panel thermal tier, or DOTP and DINCH where the OEM’s phthalate policy governs, answer the fogging gate on the compound. Match the ester family to the skin’s thermal zone and fogging limit before the compound is locked.
VDA 278 and DIN 75201 are the standards an interior skin must clear. The selection detail by temperature tier and ester family is a separate question from this material decision.
Where the Polyolefin Skin Wins on Mass and End-of-Life Recyclability
A polyolefin skin weighs less than the equivalent PVC skin. PVC “suffers from being heavier than alternative materials” in Dow’s own patent language (US 9,505,868 B2).
The regulatory landscape is shifting toward dated recycled-content targets. The EU End-of-Life Vehicles Regulation was adopted on 29 June 2026 and entered into force on 13 August 2026, setting mandatory recycled plastic content of 15% from 2032 and 25% from 2036.
The regulation also requires a share of the recycled plastic to come from end-of-life vehicles, creating a closed-loop obligation that favours single-material streams.
A PVC skin compound that is roughly a quarter plasticizer by weight is not a single-material stream. On this axis, the polyolefin skin has the cleaner answer.
When to Choose TPO and When to Choose PVC
Programs bound by mass or recyclate content point to the polyolefin skin. Programs bound by grain fidelity, cost or the established process route point to PVC.
| Governing constraint | TPO | PVC |
|---|---|---|
| Mass target binding | Lighter per part | Heavier per part |
| Recyclate quota (ELV) | Single-material stream | ~25% plasticizer by weight; harder closed-loop path |
| Grain depth, sharp radii, two-tone | Narrower window, higher scrap | Finer grain, deeper undercuts |
| Fogging and emission gate | No plasticizer to volatilize | Answered by ester selection at the tier |
| Phthalate-restricted spec | Same REACH entry 51 scope | Reformulate with DOTP or DINCH |
| Cost at equal grain | Surface treatment + cryogenic powder + scrap | Established slush infrastructure |
| Scratch and mar over time | Degrades with age | Not flagged as a degradation path |
The plasticizer package is what answers both the restricted-ester and fogging lines for a PVC skin.
The polyolefin patent literature acknowledges that scratch resistance degrades over time with TPO products (US 2022/0127447 A1).
Where Most Programs Misread the Specification
The common mistake is collapsing the restricted-ester clause, the fogging limit and the end-of-life commitment into a single material verdict.
For programs where mass and recyclate-content targets govern, the polyolefin skin wins honestly. For instrument panels and door panels where grain fidelity, cost per finished part and the established process route govern, a PVC skin compound with the right ester family remains the shorter path to homologation.
The market trend across applications is toward specifications that separate those three lines rather than collapsing them. A program that reads each line for what it restricts will land on the right skin material.