At present, the amount of synthetic organic polymer materials, such as plastic, fiber and synthetic rubber, is increasing, and it is still growing rapidly. But in actual use, people gradually found that this kind of material has many problems such as surface, low surface hardness and poor barrier property, difficult printing, difficult bonding, electrostatic, biocompatibility and poor surface, these problems not only seriously influence the performance of these products, but also greatly limits its application to further expand the market the.

Plastic film is one of the most important uses of plastics, accounting for about 35% of the amount of plastic. Because the relative surface area of plastic film is large, its surface problems are more prominent, which are mainly difficult to print, difficult to bond, difficult to compound, produce droplets, generate static electricity and so on. At present, the technology of plastic film surface treatment used in industry is corona, but the method is very limited and is not suitable for many bulk uses. Plasma surface modification technology has been included in the national "863" plan, but so far no technical breakthrough, the main reason is the technical requirements of high vacuum degree makes it difficult to become a major industrial product surface modification technology to solve the existing problems in the production and film products, the development of high performance and functional film products it is of great significance to expand the market, the application of plastic film.

Since 1996, the laboratory of organic materials and surface engineering, School of materials science and engineering, Beijing University of Chemical Technology has developed a new continuous production process of hydrophilic / hydrophobic asymmetric plastic film based on surface light grafting through intermittent, pilot and pilot experiments. The plastic film product produced by the new surface treatment technology still has the original hydrophobicity of the film, while the other side can adjust the surface polarity according to different needs until the complete hydrophilicity is achieved. Of course, the two sides of the film can also be treated at the same time, and a symmetric modified product can be obtained.

The technology is suitable for almost all organic plastic films, such as PE, PP, PVC, PET, nylon and so on. The characteristics of graft copolymerization make the modified layer join the chemical bond with the original basement membrane, and the properties are very stable. The development of the "long-term free droplet plastic greenhouse preparation technology, combined with the application basis and application test, after identification by the Ministry of education, and completed by the pilot industrial transition to industrialization pilot, set up a deal with the width of 2 meters of the semi continuous production demonstration device and the workshop, completed the industrialization production preparation. The production device can not only be used as a separate processing line to finish the finished film, but also can be attached to the original blown film or film production line to get high-performance or functional film products directly, and its investment cost is lower. Using this technology, the surface can make the production of plastic film on one or both sides can be free adjusted until completely hydrophilic; can also be in accordance with the needs of one or both sides of the plastic film to the introduction of functional groups or reactive groups, such as acid, alkali, hydroxyl, amino, epoxy, anhydride groups. This lays the foundation for the development of special plastic films with various novel properties. At present, there are two problems in the actual use of PE, PP, PVC, PET and other industrial packaging films, which are difficult to print and hard to adhere to.

Generally, corona treatment is needed before printing, sometimes with special primers, and expensive special printing ink. Therefore, the cost is very high and the printing quality is not good. The technology can introduce strongly polar hydrophilic groups onto the surface of the thin film, and the new surface is durable because of the chemical bond between the grafted chain and the matrix film, which can fundamentally change the existing plastic film printing technology. It can not only solve the problem of organic solvent pollution in plastic film printing, but also use traditional water-based ink to reduce the cost.  For food packaging, apart from the consideration of surface or inner layer printing, bonding and heat sealing, the barrier to oxygen, moisture and fragrance is the most important index. Excellent PE and PP barrier to water, but the oxygen barrier; PET and nylon have high isolation of oxygen, but the water is bad; PVDC has a good barrier to oxygen and water, but the film alone and film strength is poor, the high cost of PVOH (polyvinyl alcohol); is the best film of oxygen, but because it is dissolved in water and steam sterilization, a sad. Now the use of the modified membrane by this technology to the production of PE, BOPP or BOPET single hydrophilic, easy to get the composite film, PVDC coating will be high-grade food packaging film, both oxygen PVOH clip to the middle of the two PE membrane and water using PE or PP and PET composed of mid-range food packaging film, without adhesive low cost high grade aluminium plastic composite films, anti fog and anti condensation fresh-keeping bag composite packaging film.