There is a difference between hydrophobic and hydrophilic, and the hydrophobic coated car film shows its true skill!
Many invisible car protection film are advertised as having self-cleaning functions, but there is a question mark as to how effective they are. Even many film stores don’t understand. Invisible car covers films are also divided into hydrophilic and hydrophobic types. Today we are going to talk about this difference between intimacy and distance. 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 invisible car clothing, similar to the picture below.
dustry insiders analyzed that the fundamental reason for this is that the coating of the car clothing is not very hydrophobic, which causes water droplets to hang on the wall of the car clothing and not flow downward. When the water evaporates, the residual material can easily form watermarks, water stains, etc. Rain spots. If the coating is not dense enough, residual substances will penetrate 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.
Are car surface coatings divided into hydrophilic and hydrophobic? How to distinguish this? Before learning to distinguish, we must first know the concepts and differences between hydrophilic and hydrophobic. The classification of hydrophilic and hydrophobic is microscopically determined by the contact angle between water droplets and the membrane surface. A contact angle of less than 90° is hydrophilic, less than 10° is super hydrophilic, greater than 90° is hydrophobic, and greater than 150° is considered super hydrophobic.
In terms of the coating of car clothing, if you want to achieve a self-cleaning effect, theoretically, either improving hydrophilicity or improving hydrophobicity is a feasible solution. However, it should be noted that the self-cleaning effect is optimal when the hydrophilic contact angle is less than 10 degrees, while the hydrophobic surface does not need to be raised too high to achieve a good self-cleaning effect.
Some companies have done statistical experiments and found that most car films currently on the market have hydrophilic coatings. However, they also found that the current coatings on car jackets are basically not super hydrophilic at <10°, and most contact angles are between 80 and 80°. °-85°, the lowest contact angle is 75°.
Therefore, the self-cleaning effect of hydrophilic car clothing on the market is actually not ideal. This is because after the hydrophilic invisible car clothing film is applied, the area of the car body exposed to sewage becomes larger on rainy days, making it easier for stains to adhere to the paint surface and making it difficult to clean. Professionals say that 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. The reason why waterwheel clothes account for the majority. However, in solving the problem of unsatisfactory self-cleaning effect of invisible car clothing, hydrophobic car clothing has unique advantages, because hydrophobic coating and lotus leaf effect are similar.
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 talking about the hydrophobic car 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.
Hydrophobic and hydrophilic car clothing identification
Therefore, if water is poured onto the car clothing, the beads that appear dispersed and do not flow easily are mostly hydrophilic coatings; the water droplets that gather and flow away and are exposed on the surface are mostly hydrophobic coatings. Of course, the human eye judgment method is for reference only. It is more important to choose a good car clothing manufacturer and professional brand.