1、 The flame retardant demand for photovoltaic EVA encapsulation film has increased. Ethylene vinyl acetate copolymer (EVA) is widely used in the encapsulation layer of photovoltaic modules due to its high transparency, good adhesion, and flexibility. However, EVA itself is a combustible material that is prone to combustion under high temperatures or electrical faults. With the promotion of photovoltaic systems in the fields of building integration (BIPV), transportation, energy storage, etc., higher requirements have been put forward for the flame retardant level, safety, and environmental standards of EVA encapsulation films.

Therefore, the introduction of halogen-free environmentally friendly flame retardants has become an industry trend, among which * * high-purity ultrafine magnesium hydroxide (Mg (OH) ₂) * * has become an ideal flame retardant additive material in EVA packaging films due to its excellent thermal stability, low smoke, and non-toxic characteristics.

2、 The core requirements of EVA photovoltaic film for flame retardants

EVA, as a photovoltaic grade transparent material, has extremely high performance requirements for flame retardants:

Performance dimension technical requirements

High optical performance with high transmittance (>90%), no obvious haze or particle precipitation, excellent thermal stability and heat aging resistance (subject to long-term thermal cycling of ≥ 85 ° C), flame retardant level meets UL94 V-0, IEC 60695 and other testing standards, environmental standards comply with RoHS, REACH, halogen-free requirements, dispersion performance and EVA high compatibility, no aggregation or precipitation, mechanical properties do not significantly reduce tensile strength, peel strength, flexibility

3、 Technical adaptability of magnesium hydroxide in EVA photovoltaic film

1. Thermal decomposition temperature matching

The decomposition temperature of magnesium hydroxide is about 330 ℃, which is higher than the processing temperature of EVA (usually 120-160 ℃). It will not release moisture in advance during the processing, ensuring processing stability and equipment safety.

2. Heat release and absorption mechanism

Magnesium hydroxide decomposes and releases water vapor to absorb heat, dilute combustion gases, and form MgO insulation layer, significantly improving the flame retardancy of EVA film and reducing flame propagation and smoke release.

3. Low smoke, non-toxic and environmentally friendly advantages

Unlike halogenated flame retardants (such as bromine based), magnesium hydroxide does not release toxic gases or corrosive smoke during combustion, fully in line with the development direction of "green manufacturing" and "low-carbon emissions" in the photovoltaic industry.

4、 Suggestions on technical indicators for EVA specific magnesium hydroxide products

To ensure a balance between optical and flame retardant properties, the following specifications of magnesium hydroxide products should be selected:

Suggested values for indicators

Mg (OH) ₂ content ≥ 99.0%

Average particle size (D50) below 0.5 μ m (nanometer or ultrafine grade is recommended)

Whiteness (R457) ≥ 95

BET surface area ≥ 25 m ²/g

Loss on ignition (LOI) ≥ 30%

Moisture content ≤ 0.5%

PH (10% aqueous suspension) 9.5-10.5

Surface modifier (optional): Silane coupling agent or fatty acid calcium magnesium layer modification

5、 Formula design suggestions

To balance transparency, flame retardancy, and mechanical properties, the amount of magnesium hydroxide added is generally controlled at 15-25wt%. The typical flame retardant formula for EVA photovoltaic film is as follows:

EVA resin: 65-75%

Magnesium hydroxide: 15-25%

Light stabilizer/antioxidant: 1-2%

Thickener/modifier: 2-5%

Other synergists (optional): 1-3% phosphorus/silicon additives

6、 Development direction and trend

1. Nano modified magnesium hydroxide: improves transparency and dispersibility to meet the needs of high-end EVA films.

2. Synergistic flame retardant system: Develop Mg (OH) ₂+organic phosphorus and nitrogen compound composite system to reduce dosage and improve performance.

3. Green EVA alternative material: supports flame retardant modification of new packaging materials such as PVB and POE film.

Conclusion: In the context of the photovoltaic industry moving towards an efficient, safe, and green future, EVA specific magnesium hydroxide flame retardants will play an increasingly important role. Zhongmei ™ Provide ultrafine magnesium hydroxide products with controllable particle size, high purity, and strong dispersibility to assist photovoltaic packaging materials in achieving the optimal balance between flame retardancy and optical performance.

If you need further technical support or sample cooperation, please feel free to contact the China Magnesium Industry team. We customize high-performance magnesium hydroxide solutions for photovoltaic enterprises.