Analysis of Material Technology for Automotive Color Change Film: Process Differences between PVC, PET, and TPU

One of the core technologies of automotive color changing film lies in material selection, as different materials directly affect the durability, construction difficulty, and visual effect of the film. The current mainstream materials include PVC, PET, and TPU, which have significant differences in molecular structure, processing technology, and performance.

PVC material: As the mainstream material for early color changing films, PVC (polyvinyl chloride) occupies the mid to low end market with its cost advantage. The production process is mainly based on the casting method, which involves mixing PVC resin with plasticizers and stabilizers and extruding them into a film. This material has limited flexibility and is prone to brittleness in low temperature environments. Long term exposure to ultraviolet radiation can cause yellowing and cracking. For example, a certain brand of PVC color changing film showed significant fading and small cracks on the film surface after one year of outdoor use. However, PVC is still suitable for short-term decorative needs,  such as car show displays or temporary color changes.

PET material: PET (polyethylene terephthalate) color changing film is made through biaxial stretching process, which has high transmittance and UV resistance. The surface is coated with optical grade acrylic adhesive to ensure no orange peel pattern after construction. A certain experimental data shows that after 3 years of outdoor exposure, the color difference value Δ E of PET modified film is still below 2.5, far superior to PVC material. However, PET film has poor ductility and requires the use of a hot air gun to assist in the construction of body parts with large curvature, such as the hood, otherwise it is prone to warping.

TPU material: TPU (thermoplastic polyurethane) color changing film adopts the casting coating process, which blends TPU particles with functional additives and extrudes them into a film. The amino ester groups in its molecular chain endow the material with excellent elasticity and self-healing ability. A certain brand of TPU color changing film can be stretched to 300% of its original size without breaking under 80  ℃  hot air gun treatment, and scratches can be automatically repaired within 24 hours at 40  ℃  environment. In addition, the chemical corrosion resistance of TPU film enables it to resist the erosion of pollutants such as bird droppings and gum, with a service life of over 5 years.

Process comparison: During the construction of PVC film, alcohol is required to clean the vehicle body, which increases the risk of adhesive residue;  PET film needs to be operated in a dust-free workshop with strict requirements for environmental humidity;  TPU film supports wet bonding process, increasing construction efficiency by 30%. From an environmental perspective, TPU has a recycling rate of 90%, which complies with the EU REACH regulation, while PVC may release dioxins during incineration.

The future technological trend will focus on multi-layer composite structures, such as combining TPU substrates with PET optical layers, balancing flexibility and transparency. The application of nano coating technology will further enhance the hydrophobicity and anti fouling ability of the membrane, and extend the maintenance cycle.