Production Process of Protective Film

PE protective film is a thin film material with surface protection function and is also one of the most important products in pressure-sensitive adhesives (PSA). The protective film is usually made of polyolefin plastic film as the substrate and acrylic polymer as the pressure-sensitive adhesive matrix resin. The true meaning of protective film is a temporary protective measure taken to prevent surface scratches during the storage, transportation, and circulation of goods, or between substrate processing. Protective film is widely used for surface protection of aluminum plates, aluminum-plastic composite panels, mirror steel plates, color plates, organic glass panels, decorative panels, aluminum profiles, plastic steel profiles, stainless steel coils, marble, and display screens. What are the structural and material characteristics of PE protective film?

The protective film is generally a polyacrylate protective film. The basic structure of polyacrylate protective film is: from top to bottom, it is: isolation layer; Printing layer; film; Adhesive layer.

Next is the film, which is usually made of low-density high-density polyethylene (PE) and polyvinyl chloride (PVC). It can be obtained through extrusion, injection molding, and blow molding. Due to its affordability and environmental friendliness, 90% of films are made of polyethylene, mainly using blow molding technology. There are many types of polyethylene, with different melting points and densities.

Another one is colloids

The key to the quality of protective film depends on the characteristics of the colloid. There are two types of pressure-sensitive adhesives used in protective films: solvent based polyacrylate adhesives and water-soluble polyacrylate adhesives, which have different characteristics.

Production process of protective film

Firstly, blown film: In the heated drum, polyethylene particles are pushed into the circular die mouth by screws, compressed air blows the molten liquid, and after air cooling, it is rolled into a film. The properties of blown film in the horizontal and vertical directions are different. The machine direction elongation of the protective film is generally greater than 180%, and the horizontal elongation is generally greater than 380%. But the magnitude of elongation is inversely proportional to the mechanical strength. If the elongation is too high (such as greater than 500%), the mechanical strength of the film is often very low, which can easily cause damage to the protective film during transportation and handling. Moreover, when unwinding, the protective film is easily stretched, and after cutting, the protective film will rebound and curl.

Next is the coating of colloids: the corona treated film can be directly coated with polyacrylate glue without the need for a primer. Then the protective film is heated through a longer air heating channel (80~120 ℃) to ensure that water or solvent is evaporated. The protective film is then cooled by a cooling roller and finally wound up.

Finally, rewinding, slitting, and storage: the protective film is directly rewound onto the coating machine to the length required by the customer. If the customer needs a protective film with a beautiful appearance and no bubble wrap, a high-quality rewinding machine can be used to ensure that there is no air wrap. For short protective films (below 500 meters), a straight knife can be used to cut them. Beyond 500 meters, the heat generated when cutting with a straight knife may cause the polyethylene to melt, making it difficult to unwind and even tearing the film. According to Coating Online, protective films can generally be stored in a warehouse at room temperature of 30 ℃ without direct sunlight for 12 months. The higher the temperature, the shorter the storage period. For every 10 ℃ increase, the storage period will be reduced by half.