The film pasted on the surface of automobile glass, commonly known as automobile film and explosion-proof film, was originally called solar film, so as the name implies, automobile film is used to deal with the scorching sun and ultraviolet rays in summer. Explosion-proof membrane has explosion-proof function besides heat insulation and light isolation. High-quality explosion-proof film uses special polyester film as the base material, and the film itself has strong toughness and is equipped with special pressure-sensitive adhesive. When an accident occurs, the broken glass will be stuck by the car film and will not splash and hurt people. Automobile explosion-proof membrane also has the function of one-way perspective and reducing glare.
In modern solar film production technology, aluminum, gold, copper, silver and other metals often use vacuum spraying or magnetron sputtering technology to make multi-layer to dense metal films with high thermal insulation [1]. In general, shell electrons (free electrons) in metallic materials are not bound by nuclei. When the light wave irradiates, the electric field of the light wave makes the free electrons absorb the energy of the light, produce oscillation with the same frequency as the light, and then release the light with the same frequency as the original light, which is called light reflection. The higher the conductivity of metal, the shallower the penetration depth and the higher the reflectivity. These metal layers will selectively reflect all kinds of heat energy in the sun, including infrared, ultraviolet and visible light heat energy, and then the color on the film will absorb the solar heat radiation and release it to the outside for the second time, and take away part of the heat with the outdoor airflow, thus effectively playing the role of heat insulation.
1) The first generation automobile film is a coating composite process film, which was called sun paper in the early days, also called "tea paper". The main function is to block the strong sunlight. This kind of automobile film is produced earlier, basically does not have heat insulation function, and it is very easy to fade (usually turns purple), and it is easy to blister after long-term use.
2) The second generation automobile film is a "dyed film". The common dyeing method for automobile films in the market is deep dyeing, and the heat absorber is added through the deep dyeing method to absorb the infrared rays in the sun, so as to achieve the effect of heat insulation. However, after heat absorption and saturation, it will produce far infrared rays for secondary radiation, which is more harmful to human body. However, because it also absorbs visible light, the visible light transmittance is not enough, and the definition is poor due to the limitation of its own technology. Another big weakness is that the heat preservation function decays quickly, and it is easy to fade, and the price is relatively cheap.
3) The third-generation automobile film is a "vacuum thermal evaporation film", which adopts a vacuum thermal evaporation process, that is, an aluminum layer is evaporated on the substrate to achieve heat insulation effect. This is also commonly referred to as the field of metal films. Most of them only contain a single layer of metal, and the metal layer is uneven. Although they have lasting thermal insulation, their weakness lies in their low definition, which affects the comfort of the field of vision. Another outstanding weakness is their high reflexes. Similar to the high reflection of mirror surface, it is easy to cause light pollution, and some products are designed to reduce reflection; The glue in the film is mixed with dye, which is easy to age and fade.
4) The fourth generation automobile film is "metal magnetron sputtering film". The magnetron sputtering process has undergone many technological innovations. Advanced aerospace alloy materials such as nickel, silver, titanium, gold, etc. cooperate with the most advanced multi-cavity high-speed rotating equipment, and use the principle of electric field and magnetic field to evenly sputter metal particles on a high-tension PET substrate at high speed and high intensity (multiple layers of metals can be sputtered on a film at the same time), thus effectively blocking the heat of infrared rays through reflection. However, because the metal layer is large and thick, it will affect the communication signal to some extent, and the reflection is high. If it is used and maintained improperly, it is easy to oxidize, which will affect the thermal insulation performance and beauty. The representative brands of technology are: Northern Lights, Gu Wei and so on.
5) The fifth generation automobile film is ceramic film, which is a kind of heat insulation film made of metal or dyeing process. It is called "IR film" or "heat absorption film" internationally. Coatings containing ITO\ATO (metal oxide powder) strongly absorb infrared rays and ultraviolet rays. Compared with metal film, it solves the problems of oxidation and shielding of metal layer, but when the absorbed heat reaches a certain saturation. The representative brands of the process are: 3M, amber optical nano-ceramic thermal insulation film (successfully applied for global patent of multilayer nano-ceramic thermal insulation film +0: 6,188,512 in February 2006) and so on.
Membrane selection skills
Automobile thermal insulation film can be divided into front windshield, rear windshield and side windshield. Among them, the highest requirement for thermal insulation film is the front windshield. According to the traffic safety regulations of the Ministry of Public Security, the light transmittance of the front windshield must be greater than 70% without affecting traffic safety. The front windshield is the most taboo to stick a dark heat insulation film. In addition, when choosing the anti-ultraviolet index of heat insulation film, the higher the better, because it can protect the parts of the center console and prevent it from aging ahead of time due to long-term exposure to the sun.
The side windshield thermal insulation film is also based on the premise that it does not affect the owner's observation of the rearview mirror. The optional heat insulation film for the side windshield is more flexible and the color is more changeable. For example, some car owners like blue insulation film. In addition, the thermal insulation effect of thermal insulation film is not directly related to the color depth, but the coating process in thermal insulation film is the key factor to determine the thermal insulation effect.
How to choose explosion-proof membrane
In the traditional sense, "explosion-proof film" refers to a solar film coated with a metal layer. This kind of solar film is higher in grade and more expensive than the ordinary adhesive dyed film, but these "explosion-proof films" are not all real explosion-proof films, and they all have explosion-proof and theft-proof functions.
Real explosion-proof solar films are mainly classified according to their thickness. For example, the thickness of the solar film seen in the general market is only 1.5 mil, no matter it is very cheap or most expensive. If the thickness is 1.5 mil, the anti-theft performance is the same regardless of the cheapest or most expensive. If we stick a film of 1.5mil, but if the thickness of the solar film exceeds 4mil, we will have a certain anti-theft effect by sticking it on ordinary glass. This is the real automobile explosion-proof membrane, and the tensile strength per square centimeter should reach more than 2000 kg. Moreover, if the pasted car glass is hit, the car film can also prevent the broken glass from splashing and hurting people, which can greatly protect the passengers in the car from being stabbed by the glass.
In addition, the real explosion-proof membrane should also have heat insulation, 99% ultraviolet protection, scratch-proof layer on the surface and good light transmittance. When purchasing automobile safety explosion-proof film, you should understand the selection criteria of the above combinations and make sure that you won't make a mistake before buying it, so as to buy a real explosion-proof solar film. Provide a few better films, 3M and Dragon Film are both good and expensive. Meissen membrane has good quality and high cost performance, which is the representative of medium and high-grade membrane.