Introduction to BOPP film mechanical properties

1. Tensile strength: The tensile strength is mainly reflected in the tear resistance of the film. ForBOPP films, the primary tear strength is higher and the secondary tear strength is lower. In general, we require films with high tensile strength, which will minimize the breakage of the film during the packaging process. As a packaging film, BOPP films in China generally require a longitudinal direction of 140N / mm2 or more and a transverse direction of 220N / mm2 or more.

2. Elongation at break: The elongation at break mainly reflects the stiffness of the film. The lower the elongation at break of the film, the better the brittleness, the easier it is to cut when the machine is on the machine, and the patency of the film in the cutting operation is virtually increased. BOPP film generally requires less than 200% in the longitudinal direction and less than 80% in the transverse direction.

3. Modulus of elasticity The modulus of elasticity reflects the rigidity of the object. For BOPP films, with the same thickness, the elastic modulus directly affects whether the film is stiff or soft, which affects the smooth operation of the film and the effect of packaging. Because the elastic modulus is too small, the film is soft and poor in rigidity, which results in cutting and running poorly, and even the phenomenon of loose packages and film blockages, resulting in poor packaging appearance and squeezing cigarettes. BOPP film generally requires elastic modulus above 2000N / mm2. Of course, there is a big difference in the elastic modulus between the initial offline of the film and the inventory after 15 days, which is increased by about 500-1000N / mm2. This is mainly because after the film is produced, there is a process of continuous crystallization, that is, the crystallization is perfect, after 15 days The crystallization is basically complete. In addition, the elastic modulus and temperature of the film have a great relationship. Generally speaking, each time the temperature rises by 2 ° C, the elastic modulus decreases by about 150 to 250 N / mm2. Therefore, the relatively stable detection environment is crucial to the accuracy and reasonableness of the detection data.