Dioctyl Terephthalate (DOTP) has emerged as one of the most important non-phthalate plasticizers in the modern plastics industry. This comprehensive guide explores our advanced production technology and quality control systems for premium DOTP.

Chemical Reaction Principle

The production of DOTP involves the esterification of terephthalic acid with 2-ethylhexanol in the presence of a titanium-based catalyst. The overall chemical reaction can be represented as:

Manufacturing Process Overview

Raw Material Selection and Quality Control

The production of high-quality DOTP begins with careful selection and testing of raw materials according to strict specifications:

• Terephthalic Acid (TPA): Purity ≥99.9%, moisture content <0.1%, particle size optimized for rapid dissolution
• 2-Ethylhexanol (2-EH): Purity ≥99.5%, water content <0.1%, distillation range within 1°C
• Catalyst System: Proprietary titanium-based catalyst (tetrabutyl titanate), concentration precisely controlled at 0.05-0.15% by weight

Esterification Reaction Stage

The core of our DOTP production involves a carefully controlled continuous esterification process in multi-stage reactors:

1. Temperature Control: Precisely maintained at 220-250°C using advanced PID controllers with ±0.5°C accuracy
2. Pressure Management: Operated under vacuum conditions (-0.08 to -0.095 MPa) to facilitate water removal
3. Reaction Time: Optimized residence time of 4-6 hours for complete conversion (>99.8%)
4. By-product Removal: Continuous azeotropic distillation removes water, driving equilibrium toward product formation
5. Nitrogen Blanketing: Inert nitrogen atmosphere prevents oxidation and maintains product color stability

Purification and Finishing

After esterification, the crude DOTP undergoes multiple purification steps:

• Neutralization: Residual acidity neutralized with sodium carbonate solution
• Stripping: Unreacted alcohol removed under high vacuum (<1 mmHg) at 180-200°C
• Filtration: Multi-stage filtration through 10μm, 5μm, and 1μm cartridge filters
• Quality Testing: Every batch tested against 15+ quality parameters before release

Comprehensive Quality Parameters

Our DOTP product meets or exceeds international industry standards including ASTM D5208 and ISO 10502:

Parameter	Specification	Test Method	Typical Result
Ester Content	≥99.5%	GC (Gas Chromatography)	99.7%
Acid Value	≤0.1 mg KOH/g	ASTM D974	0.05 mg KOH/g
Color (APHA)	≤30	ASTM D1209	15-20
Moisture Content	≤0.10%	Karl Fischer Titration	0.05%
Density (20°C)	0.983-0.987 g/cm³	ASTM D4052	0.985 g/cm³
Flash Point	≥200°C	ISO 2592	210°C
Volume Resistivity	≥1×10¹⁴ Ω·cm	ASTM D257	2.5×10¹⁴ Ω·cm

Key Application Areas

DOTP's superior properties make it the preferred choice for demanding applications:

Our Superior DOTP is manufactured under ISO 9001:2015 certified processes with an annual capacity of 300,000 metric tons. Contact our technical team for product samples and application guidance.

• PVC Wire and Cable Compounds: Excellent electrical insulation properties (volume resistivity >10¹⁴ Ω·cm), low volatility ensures long-term performance
• Medical-grade Flexible PVC: Non-phthalate formulation, biocompatible, complies with EU REACH and FDA regulations
• Food Packaging Films: Low migration rate, odorless, suitable for direct food contact applications
• Synthetic Leather Production: Superior flexibility at low temperatures (glass transition temperature <-40°C), excellent abrasion resistance
• Automotive Interior Materials: Fogging resistance, UV stability, meets OEM specifications for interior components
• Sealants and Adhesives: Good compatibility with various polymers, low viscosity improves processing efficiency