22/03/2024
In recent years, as the number of cars continues to grow and the demand for paint maintenance continues to escalate, invisible car coverings have gradually been endowed with rigid needs by the end consumer market.
As we all know, car PPF have anti-scratch, tear-resistant and other properties. These properties are derived from the TPU base material of the car PPF. A good TPU material has strong protection for the paint surface and has a long service life. Another important function of car clothing - self-cleaning, self-repairing and high brightness, is also very important. These functions originate from the coating on the surface of the TPU base material. The quality of the coating not only determines the excellent self-cleaning performance, but is also one of the important factors that determine the appearance of your car. Therefore, when consumers purchase car PPF, in order to ensure the daily appearance of their cars, they pay special attention to the self-cleaning performance of the coating.
Many TPU PPF are advertised as having self-cleaning functions, but there is a question mark as to how effective they are. Even many car care stores don’t understand. TPU PPF are also divided into hydrophilic and hydrophobic types.
Some car owners have discovered during use that after it rains, when the water evaporates, black or white rain spots will appear on the surface of the car clothing.
The fundamental reason for this is that the coating of the car PPF is not very hydrophobic, which causes water droplets to hang on the wall of the car protect film and not flow downward. When the water evaporates, the residual material can easily form watermarks, water stains, and rain spots. If the coating is not dense enough, residual substances will pe*****te into the interior of the membrane, resulting in rain spots that cannot be wiped off or washed off, which may even seriously affect the service life of the membrane.
The production process of hydrophilic coating is simpler and cheaper than that of hydrophobic coating; while hydrophobic coating requires the addition of additional nano-hydrophobic and oleophobic materials, and the process requirements are extremely demanding and cannot be achieved by most factories.
However, in solving the problem of unsatisfactory self-cleaning effect of car paint protection film, hydrophobic car clothing has unique advantages, because hydrophobic coatings have the same effect as the lotus leaf effect.
The lotus leaf effect means that after rainfall, the rough microscopic morphology and epidermal wax on the surface of the lotus leaf prevent the water droplets from spreading and adsorbing on the leaf surface, but form water droplets. The leaf surface sways slightly with the wind, and the water droplets will slide off. At the same time, dust and dirt on the leaves are taken away.
When placed on a hydrophobic car paint protection film, it will appear as if rainwater falls on the surface of the film. The rainwater will form water droplets due to the surface tension of the hydrophobic coating. Under the action of its own gravity, the water droplets will easily roll down and leave the film surface. The rolling water droplets can also take away the dust and sludge on the membrane surface, achieving a self-cleaning effect.
How to tell whether a car coating is hydrophilic or hydrophobic?
There are two main ways:
1. Test the contact angle with the help of professional instruments
2. Make a preliminary judgment based on the water rolling off the membrane surface.
Generally, water droplets will form on a hydrophilic surface, which are easily adsorbed on it. Water droplets cannot be seen on super hydrophilic surfaces, and only the wet surface will be seen. Water droplets will also form on hydrophobic surfaces, but they will flow under the action of gravity. , gather and flow away, the surface is still dry, and the superhydrophobic effect is more obvious.
