Durability technology of automotive color changing film: from material aging to environmental adaptability research

The durability of color changing film is one of its core values, which requires long-term performance stability through material modification, structural design, and testing verification. This article will explore from three perspectives: aging mechanism, protective technology, and lifespan prediction.

1. Material aging mechanism and protection

The aging of the color changing film is mainly caused by ultraviolet radiation, thermal oxidation, and chemical corrosion. Protection techniques include:

UV absorber: Add benzotriazole compounds to convert ultraviolet light below 340nm into thermal energy. A certain experiment showed that the color difference Δ E of the modified film with 2% ultraviolet absorber added after 500 hours of xenon lamp aging was only 2.1.

Antioxidant system: A combination of hindered phenols (such as Irganox 1010) and phosphites (such as Irgafos 168) is used to inhibit free radical chain reactions. After thermal oxidative aging (100 ℃/72h), the tensile strength retention rate of a TPU modified film reached 92%.

Chemical resistant coating: Coating the film surface with a fluorinated polymer to enhance resistance to pollutants such as gasoline and bird droppings. In a certain test, the fluorine-containing coating color changing film did not swell after soaking in gasoline for 24 hours.

2. Structural design optimization

Improving the comprehensive performance of color modified films through multi-layer composite structures:

Five layer co extrusion structure: from top to bottom, there are protective layer, color layer, substrate layer, adhesive layer, and release layer. A certain brand adopts this structure, which improves the scratch resistance and adhesion of the color changing film by 30% and 20% respectively.

Nanocomposite substrate: Add 5% montmorillonite nanosheets to TPU to form an intercalated structure. A certain experiment showed that the modulus of the nanocomposite color modified film was increased to 1200MPa, and the puncture resistance strength was increased by 40%.

Self repairing coating: Introducing dynamic covalent bonds (such as disulfide bonds) on the surface to achieve scratch self-healing. In a certain case, after 80 ℃ hot air treatment, scratches with a width of 0.2mm can completely disappear within 15 minutes.

3. Environmental adaptability testing

The color changing film needs to undergo rigorous environmental testing to verify its durability:

Climate cycle test: Cycle 100 times under conditions of -40 ℃ to 85 ℃ and 95% humidity, with no delamination or bubbling on the membrane surface.

Stone impact test: Use a steel shot with a diameter of 6.35mm to impact at a 45 ° angle and a speed of 50km/h, without penetrating damage to the membrane surface.

Salt spray corrosion test: the glue layer has no corrosion trace after being spray for 1000 hours in 5% NaCl solution.

life prediction model

Based on the Arrhenius equation and accelerated aging test, a prediction model for the lifespan of the color changing film can be established. A study shows that under the conditions of 2000 hours of sunshine per year and an average temperature of 25 ℃, the expected lifespan of a TPU modified film is 8 years, while that of a PVC modified film is only 3 years.