What is the difference between plasticizer DOP and DOTP?

DOP (Dioctyl Phthalate) and DOTP (Dioctyl Terephthalate) are both widely used plasticizers in flexible PVC formulations, particularly for cable, film, and synthetic leather. However, they differ in chemical structure, regulatory compliance, migration behavior, and target applications.


1. Chemical Structure and Molecular Properties

DOP and DOTP share similar molecular weights and boiling points but differ in structure. DOP is an ortho-phthalate, while DOTP is a terephthalate, making DOTP a non-phthalate alternative with a different safety and regulatory profile.

Property DOP (DEHP) DOTP
Chemical Name Di(2-ethylhexyl) phthalate Di(2-ethylhexyl) terephthalate
Structure Base Ortho-phthalate Terephthalate (para-isomer)
Molecular Formula C24H38O4 C24H38O4
Molecular Weight ~390.56 g/mol ~390.56 g/mol
CAS Number 117-81-7 6422-86-2
Type Phthalate Non-phthalate

2. Functional Performance in PVC

DOTP and DOP both offer good plasticizing efficiency, but DOTP performs better in low-migration, low-volatility, and weather-resistant applications. It also produces fewer volatile organic compounds (VOCs) and has lower fogging.

Property DOP DOTP
Plasticizing Efficiency High High
Flexibility Retention Good Better over time
Migration Resistance Low High
Volatility Higher Lower
Heat Aging Performance Moderate Better
Electrical Resistance Good Very good

3. Regulatory and Environmental Status

Due to health concerns, DOP has been restricted or banned in many applications, particularly in the EU and North America. DOTP is considered a safer, REACH- and RoHS-compliant alternative.

Regulation Area DOP (DEHP) DOTP
EU REACH SVHC Listed (Annex XVII) Not listed
RoHS Compliance Not allowed over 0.1% Allowed
FDA Food Contact Limited Use Conditionally approved
Toys and Medical Banned in many regions Permitted under limits
Environmental Impact Persistent, toxic Lower toxicity, biodegradable trend

4. Application Suitability

DOP is often used in general-purpose applications where cost is a priority and regulations are not stringent. DOTP is preferred in modern applications where durability, safety, and compliance are critical.

Industry/Application Preferred Plasticizer Rationale
Wire & Cable (General) DOP or DOTP DOTP for RoHS, DOP for domestic use
Automotive Wiring DOTP Low fogging and long-term flexibility
Medical Devices DOTP Non-phthalate status
Toys & Food Contact DOTP Regulatory compliance
General PVC Goods DOP Low cost, acceptable in unrestricted areas

5. Market & Cost Considerations

DOP is less expensive and widely available, but DOTP is gaining market share due to environmental compliance and shifting customer demand for safer alternatives.

Factor DOP DOTP
Cost per kg (approx.) Lower Slightly higher
Supply Availability Very High Increasing rapidly
Customer Preference Declining (due to bans) Growing in regulated markets
Lifecycle Value Short-term focused Better long-term durability and safety

Conclusion

Use DOP for cost-sensitive, domestic, or non-regulated applications where price and efficiency matter most. Choose DOTP for export, consumer-safe, or long-life applications—especially where RoHS, REACH, or FDA standards apply.

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