As the important haze of the physical and mechanical properties of BOPP thermal lamination film, it is also an important indicator for customers to choose matte film.
The main component of the industrial production of BOPP film material is PP. The isotactic PP and the syndiotactic PP have different crystal structures, forming a small wafer having an irregular size. Different petrochemical manufacturers have different differences in the raw materials produced due to their different production processes and technologies. One indicator that has the greatest impact on film haze is the yellow index. The larger the yellow index, the greater the haze of the produced film.
2. Anti-adhesive agent
The anti-adhesive agent is added to the surface of the film to improve the anti-adhesion of the film, but the turbidity and gloss of the film are affected.
This is due to the fact that anti-adhesive agents, especially inorganic anti-adherents, are incompatible with polypropylene resins. The film causes voids to form around the anti-adhesive agent during stretching and creates an interface of different refractive index between the two materials.
The size of the polypropylene crystal affects the haze of the film. Biaxial stretching can break up larger particle crystals that may be produced by polypropylene, thereby reducing crystal size, increasing light transmittance, and reducing haze.