Flame retardant Aluminum Hypophosphite and MCA for EVA Heat-Shrink Tubing
When using aluminum hypophosphite, MCA (melamine cyanurate), and magnesium hydroxide as flame retardants in EVA heat-shrink tubing, the recommended dosage ranges and optimization directions are as follows:
1. Recommended Dosage of Flame Retardants
Aluminum Hypophosphite
- Dosage: 5%–10%
- Function: Highly effective flame retardant, promotes char formation, and reduces heat release rate.
- Note: Excessive amounts may impair material flexibility; synergistic agents should be incorporated for optimization.
MCA (Melamine Cyanurate)
- Dosage: 10%–15%
- Function: Gas-phase flame retardant, absorbs heat and releases inert gases (e.g., NH₃), synergizing with aluminum hypophosphite to enhance flame retardancy.
- Note: Overloading may cause migration; compatibility with EVA must be ensured.
Magnesium Hydroxide (Mg(OH)₂)
- Dosage: 20%–30%
- Function: Endothermic decomposition releases water vapor, diluting flammable gases and suppressing smoke.
- Note: High loading may reduce mechanical properties; surface modification is recommended to improve dispersion.
2. Formulation Optimization Recommendations
- Total Flame Retardant System: Should not exceed 50% to balance flame retardancy and processability (e.g., flexibility, shrinkage rate).
- Synergistic Effects:
- Aluminum hypophosphite and MCA can reduce individual dosages (e.g., 8% aluminum hypophosphite + 12% MCA).
- Magnesium hydroxide complements flame retardancy through endothermic effects while reducing smoke.
- Surface Treatment: Silane coupling agents can enhance the dispersion and interfacial bonding of magnesium hydroxide.
- Auxiliary Additives:
- Add 2%–5% char-forming agents (e.g., pentaerythritol) to improve char layer stability.
- Incorporate small amounts of plasticizers (e.g., epoxidized soybean oil) to compensate for flexibility loss.
3. Performance Validation Directions
- Flame Retardancy Testing:
- UL94 vertical burning test (target: V-0).
- Limiting Oxygen Index (LOI >28%).
- Mechanical Properties:
- Evaluate tensile strength and elongation at break to ensure flexibility meets application requirements.
- Processability:
- Monitor Melt Flow Index (MFI) to avoid processing difficulties due to excessive fillers.
4. Cost and Environmental Considerations
- Cost Balance: Aluminum hypophosphite is relatively expensive; its dosage can be reduced (supplemented with MCA) to control costs.
- Environmental Friendliness: Magnesium hydroxide is non-toxic and smoke-suppressing, making it suitable for eco-friendly applications.
Example Formulation (for reference only):
- Aluminum Hypophosphite: 8%
- MCA: 12%
- Magnesium Hydroxide: 25%
- EVA Matrix: 50%
- Other Additives (coupling agents, plasticizers, etc.): 5%
Post time: Apr-27-2025
