无邻苯二甲酸酯增塑剂在PVC中的应用：DINCH、DPHP与柠檬酸酯性能对比
Introduction to Phthalate-Free Plasticizers in PVC
Plasticizers are critical additives in polyvinyl chloride (PVC) formulations, enabling flexibility, durability, and processability. However, regulatory pressures—particularly in Europe under REACH and in the U.S. under TSCA—have led to the phase-out of traditional phthalate plasticizers such as di-(2-ethylhexyl) phthalate (DEHP) and di-isononyl phthalate (DINP). These restrictions are driven by concerns over endocrine disruption, reproductive toxicity, and bioaccumulation.
As a result, the industry has shifted toward phthalate-free plasticizers, including:
- DINCH (Di-isononyl cyclohexane-1,2-dicarboxylate)
- DPHP (Di-(2-propylheptyl) phthalate) – though technically a phthalate, DPHP is REACH-exempt due to its linear alkyl structure and lower toxicity profile
- Citrate esters (e.g., Acetyl Tributyl Citrate, ATBC)
These alternatives offer compliance with global regulations while maintaining performance in flexible PVC applications such as medical devices, food-contact materials, toys, and automotive interiors.
Chemical Profiles and Regulatory Status
| Plasticizer | Chemical Family | CAS Number | REACH Status | Key Regulatory Notes |
|---|---|---|---|---|
| DINCH | Cyclohexane-1,2-dicarboxylate | 166412-78-8 | Registered | Approved for food contact, medical devices |
| DPHP | Phthalate (linear) | 53306-54-0 | Exempt | Listed under REACH Annex XIV (no authorization required); FDA 21 CFR §178.3740 approved |
| ATBC | Citrate ester | 77-90-7 | Registered | FDA 21 CFR §178.3910 approved; EU food contact compliant |
DINCH: The Cycloaliphatic Workhorse
DINCH is synthesized by hydrogenating DINP to form a cyclohexane ring. This structural modification eliminates aromaticity, reducing toxicity concerns. DINCH is widely recognized for:
- Low migration in medical and food-contact applications
- Excellent low-temperature flexibility (Tg ≈ -50°C)
- High thermal stability (decomposition >250°C)
It is the most established alternative in the EU and Asia, particularly in soft PVC toys and medical tubing.
DPHP: The Linear Phthalate Exception
While DPHP is chemically a phthalate, its linear alkyl chain (C10) confers low volatility and minimal endocrine activity. Key benefits include:
- Low extractables in medical and food applications
- Good compatibility with PVC (no exudation up to 50 phr)
- High thermal stability (decomposition >300°C)
DPHP is widely used in Europe as a drop-in replacement for DINP in many applications.
Citrate Esters: Biocompatible and Fast-Curing
Citrate esters, such as ATBC and tributyl citrate (TBC), are derived from citric acid and are metabolically benign. They are favored in:
- Biomedical PVC (e.g., blood bags, IV tubing)
- Food packaging (EU Regulation 10/2011 compliance)
- Eco-labeled products (e.g., USDA BioPreferred)
ATBC offers rapid fusion and clarity, making it ideal for transparent PVC films.
Formulation Performance: Comparative Data
The choice of plasticizer depends on application-specific requirements such as flexibility, volatility, migration resistance, and regulatory compliance. Below is a performance comparison based on published studies and supplier data.
Flexibility and Mechanical Properties
| Property | DINCH | DPHP | ATBC |
|---|---|---|---|
| Tensile Strength (MPa) | 15–20 | 16–21 | 14–18 |
| Elongation at Break (%) | 300–350 | 280–320 | 320–380 |
| Shore A Hardness (100 phr) | 65–70 | 68–72 | 60–65 |
| Glass Transition Temp. (Tg, °C) | -48 | -45 | -52 |
Data: Average from multiple sources including BASF and Hallstar technical bulletins.
Observations:
- DINCH and DPHP provide similar mechanical profiles, with slightly higher modulus than ATBC.
- ATBC offers superior low-temperature performance (lower Tg), ideal for cold-climate applications.
Volatility and Migration Resistance
| Property | DINCH | DPHP | ATBC |
|---|---|---|---|
| Volatility (TGA, 10% loss, °C) | 260 | 280 | 230 |
| Migration to Air (24h, 80°C, mg/g) | 1.2 | 0.8 | 3.5 |
| Migration to Simulant (food oil, %) | 0.5 | 0.3 | 2.1 |
Source: Plasti Pigments Srl, 2023 migration study.
Key Insights:
- DPHP exhibits the lowest volatility and migration, making it ideal for high-temperature or long-term applications.
- ATBC shows higher migration, particularly to lipophilic media, limiting its use in fatty food contact.
- DINCH is intermediate, balancing low migration with acceptable volatility.
Thermal Stability and Processing
| Plasticizer | Fusion Time (180°C, min) | Decomposition Onset (°C) |
|---|---|---|
| DINCH | 8–10 | 255 |
| DPHP | 9–11 | 285 |
| ATBC | 5–7 | 220 |
- ATBC fuses fastest due to its low molecular weight and rapid solvation of PVC.
- DPHP offers the highest thermal stability, suitable for high-temperature extrusion or calendering.
Recommended Dosage Ranges in PVC
Dosage depends on desired hardness, flexibility, and application. Typical ranges (per 100 parts PVC resin):
| Application | DINCH (phr) | DPHP (phr) | ATBC (phr) |
|---|---|---|---|
| Medical tubing | 40–50 | 35–45 | 45–55 |
| Food-contact film | 35–45 | 30–40 | 40–50 |
| Automotive interior | 45–55 | 40–50 | Not recommended |
| Toys (EU) | 40–50 | 35–45 | 45–55 |
| Wire & cable insulation | 50–60 | 45–55 | Not suitable |
Formulation Tips:
- Increase plasticizer level to reduce hardness (e.g., from Shore A 80 to 65).
- Use co-plasticizers (e.g., 10 phr epoxidized soybean oil) to improve heat stability when using ATBC.
- Avoid ATBC in high-temperature applications (>120°C) due to volatility.
- DPHP pairs well with DINCH (e.g., 60:40 blend) for balanced performance in automotive interiors.
Case Studies: Real-World Applications
1. Medical Tubing: DINCH vs. ATBC
A European medical device manufacturer switched from DEHP to DINCH in PVC tubing. After 12 months of use:
- Migration to blood simulant: <0.1 µg/L (compliant with ISO 10993)
- Mechanical retention: 92% elongation after 4 weeks at 40°C
- Regulatory clearance: EU MDR compliant; FDA Master File available
ATBC was trialed but rejected due to higher extractables in ethanol-based disinfectants.
2. Automotive Interior: DPHP Blend
An OEM replaced DINP with a 60:40 blend of DPHP and DINCH in dashboard skins. Results after 1,000h at 85°C/85% RH:
- Odor reduction: 60% lower than DINP formulation
- Dimensional stability: <1% shrinkage
- Long-term flexibility: Shore A retained at 70 (initial: 68)
DPHP’s low volatility reduced fogging, improving cabin air quality.
3. Food Packaging: ATBC Limitation
A flexible film producer used ATBC in PVC cling wrap. After 30 days in olive oil at 23°C:
- Migrated plasticizer: 2.1% (exceeds EU limit of 0.1% for non-ionic migrants)
- Film clarity: Slight haze due to phase separation
Recommendation: Switch to DINCH or DPHP for fatty food contact.
Processing Considerations
Compatibility and Stability
- DINCH and DPHP: Compatible with all PVC stabilizers (Ca/Zn, Ba/Zn, Sn). Use 1.5–2.5 phr stabilizer for thermal protection.
- ATBC: Can destabilize PVC at >150°C. Always use epoxy co-stabilizers (e.g., 2 phr ESO).
Blending Strategies
- DINCH + ATBC (70:30): Improves low-temperature performance without sacrificing migration resistance.
- DPHP + DINCH (50:50): Balances cost, performance, and regulatory compliance.
Shelf Life and Storage
- Store in sealed containers under nitrogen to prevent oxidation (especially ATBC).
- Shelf life: DINCH and DPHP – 24 months; ATBC – 12 months at <25°C.
Cost and Availability in 2024
| Plasticizer | Approx. Cost (USD/kg) | Supply Stability | Key Suppliers |
|---|---|---|---|
| DINCH | 2.80–3.20 | Stable | BASF, Evonik, Songwon |
| DPHP | 2.40–2.90 | Stable | BASF, Eastman, Oxea |
| ATBC | 3.50–4.20 | Moderate | Jungbunzlauer, Hallstar, Vertellus |
Note: Prices fluctuate with crude oil and feedstock (n-butanol, 2-ethylhexanol). DPHP is the most cost-effective alternative to DINP.
Environmental and Toxicological Profile
| Plasticizer | Toxicity | Biodegradability | Food Contact |
|---|---|---|---|
| DINCH | Low (no endocrine disruption) | >80% in 28 days | EU and FDA approved |
| DPHP | Low (linear alkyl) | >75% in 28 days | EU and FDA approved |
| ATBC | Very low (GRAS status) | >90% in 14 days | EU and FDA approved |
Endocrine Activity (in vitro, ER/AR assays):
- DINCH: IC50 >100 µM (no effect)
- DPHP: IC50 >50 µM (low activity)
- ATBC: IC50 >500 µM (minimal activity)
Source: EFSA Scientific Opinion, 2021.
Conclusion: Selecting the Right Plasticizer
The optimal phthalate-free plasticizer depends on the application’s thermal, mechanical, and regulatory demands:
- Choose DINCH for medical devices, toys, and general-purpose flexible PVC requiring balance of performance and compliance.
- Choose DPHP for automotive interiors, high-temperature applications, or when minimizing migration is critical.
- Choose ATBC for eco-certified products or where low-temperature flexibility and rapid fusion are priorities—but avoid in fatty food contact.
Always conduct small-scale trials to validate compatibility with stabilizers, pigments, and processing conditions. Use third-party migration testing (e.g., ISO 177 or EU 10/2011) to confirm regulatory compliance.
Summary
As global regulations eliminate legacy phthalates, DINCH, DPHP, and citrate esters have emerged as robust alternatives for PVC formulators. Each offers distinct advantages in flexibility, migration resistance, and regulatory compliance. DINCH leads in medical and toy applications, DPHP excels in automotive and high-heat scenarios, while ATBC is ideal for transparent, low-temperature films—with careful consideration of its higher extractables. By leveraging these alternatives, formulators can achieve safe, sustainable, and high-performing flexible PVC across industries.
Chemzip supplies high-purity DINCH, DPHP, and ATBC plasticizers from leading global manufacturers, with technical support for formulation development and regulatory documentation. Contact our team for sample requests, SDS, or application-specific guidance.
Disclaimer: The data presented are derived from published sources and supplier technical bulletins. Results may vary based on formulation, processing conditions, and end-use environment. Always validate through internal testing.