Study Of The Structure And Performances Of BOPP Tobacco Film

BOPP film is one of the most developed products of polymer film nowadays. The film is colorless and transparent, with beautiful gloss on its surface. Compared with CPP, BOPP has better mechanical behavior, more stable dimension, stronger resistance to low-temperature and high-temperature, and better barrier property. What's more, its price is lower than any other biaxially-stretched film such as BOPET and BOPS. So BOPP has become a kind of plastic packing material with higher price versus performance ratio at present.The BOPP film has many uses: 甪or civil use, it is mainly for packing, e.g., wrapping of bread, sweet, biscuit, etc., of medicine and one-time medical apparatus, and of various middle- and high-grade cigarettes; (2)for industrial use, it is mainly for dielectric film of electrical appliance, cable markers, static-insulating materials, and ornaments.The internal structure of polymer materials stipulates their property. PP is a kind of crystalline polymer, so its structure with crystalline region and amorphous region determines the bulk property of BOPP. By employing the characterization methods of X-ray and DSC, this paper conducts a research on films of different stretch ratio. The results show that after the film stretched successively in two orthogonal directions, the orientation elements of all levels, such as the crystal grains in PP crystalline region, the molecular chain and segment in amorphous region, etc., arrange directionally and orderly in the stretch direction, and the crystallinity and the orientation are improved; with the stretch ratio changing, the structural factors of PP like the microcrystalline and distribution, the microstrain, and the orientation factors of crystalline region all change apparently. All of these changes of structure are connected directly with the heat and stress history in the processing of BOPP.As a kind of industrial product, BOPP still has some problems remaining unsolved. This paper will study and try to discuss three of them.1. The high-speed wrapping pipeline can scratch BOPP film with friction. So the scratch affects the appearance of the product. Thus the relevant raw materials, additives and working parameters are adapted to producing anti-scratched BOPP film. Then the two films are rubbed under the same condition and then observed respectively for their appearance under the Atomic Force Microscope (AFM). The result shows that the anti-scratched film is more wearproof than the common film.2. If BOPP film is laid up for period of time after it is cut, it will shrink and curve. That could produce effects on its application. This kind of situation derives from the uneven heat in the process of production. In this research, the process is added with a step of annealing before it is wound up. Then a special method is exerted to make a contrasting test. The result of the test shows that the annealed film has more stable dimension than the unannealed one. Thus the problem of shrinking and curving is settled to certain degree. The time-dependence of optical performance of BOPP film is connected with its relaxation process. This paper will study in this field.3. The optical property of BOPP gets weaker and weaker with the increase of time when it is laid up, which exerts a great effect on its application. That can be seen as a result from the additives' migrating to the surface of the film. Through using the Attenuated Total Reflection Infrared (ATR-FTIR), the skill of Contact Angle (CA), and the optical test of the samples, this research studies the films laid up under different condition. The results of the study show that with the time passing by, the antistatic, and the lubricant added in the internal layer (in the production) migrate more and more to the surface; the higher the temperature, the faster the migration. The amount of the additive migration is relative to the optical property of the film, i.e., the larger the amount, the weaker the optical property.