1. Comparison of the structure of window film and paint protection film
Invisible car clothing, also known as paint protection film, is named invisible because of its transparent characteristics. With the development of application requirements, car clothing and color change film gradually overlap, such as dazzling car clothing, real paint film and other categories, the main feature is to use TPU film as the base material. Structurally, the car coating film is composed of two layers of release film, functional coating, glue and TPU base film.
Schematic diagram of the structure of the car coat
Window film, also known as heat insulation film and sun film, is mainly installed on the side windows, sunroofs, rear windows and other positions. According to the different insulation materials, window films are mainly divided into two types, namely metal film and ceramic film. Generally, the metal film adopts magnetron sputtering process, and the ceramic film adopts the coating process.
Schematic diagram of the window film structure
Second, the difference between window film coating and invisible car coat coating
The functional coating of the invisible car coat and the anti-scratch coating (wear-resistant coating) of the window film are both coated on the outermost layer, and the polyurethane acrylate is used, the difference is that the functional coating of the invisible car coat is a heat-curing system, while the wear-resistant coating of the window film is a UV light curing system, and the proportion of components used is also different, and the window film coating is harder than the car coat coating.
1. Anti-scratch coating for window film
After the window film is pasted, the surface of the window film replaces the glass surface in contact with the outside world, so the outer layer of the window film needs to have a certain hardness and scratch-resistant performance, so as not to be scratched in daily use (such as window take-off and landing, etc.), resulting in blurred vision. This is where the anti-scratch layer of the window film comes in.
--Source: "Protective film against blue light and blocking ultraviolet rays", CN105385376B
Source: sartomer.arkema
Polyurethane acrylate (PUA) has urethane bonds in the molecule, which can form a variety of hydrogen bonds between the polymer chains, so that the cured film has excellent wear resistance and flexibility, high elongation at break, good chemical resistance and high and low temperature resistance, good impact resistance, and good adhesion to plastic and other substrates.
2. Functional coating of invisible car clothing
When the car body is scratched or slightly impacted, on the basis of not damaging the base film of the car coat, it will be treated with hot water or hot air, and the fine scratches will gradually disappear, and the surface of the car will be restored as before. In addition, the coating also needs to have a certain degree of elongation, softness and hardness, anti-permeation performance, slip performance, aging resistance, acid and alkali resistance, solvent resistance, hydrolysis resistance, etc.
At present, most of the self-healing coatings used on car coatings are acrylic polyurethanes made of polyhydroxyacrylates, flanine isocyanate-resistant monomers copolymerized, which are mainly based on the hydrogen bond self-healing mechanism in the intrinsic type, and can achieve self-healing under the action of hydrogen bonds, polymer chain segment movement, heat and other factors.
Figure The principle of hydrogen bonding self-healing, derived from the science of solidification
