Abstract:

The composite structure of a three⁃layered matting and heat⁃sealing film was designed by selecting suitable polyethylene （PE） and polypropylene （PP） as visual layer materials and adding micron SiO₂ into the core layer to improve the haze of the film. The film was prepared by using a three⁃layer co⁃extrusion casting method， and its properties were investigated. The results indicated that PE⁃HD and copolymerization⁃type PP could be combined to form the best matting material. With an increase in the PE⁃HD content in the visual layer， the PE⁃HD/PP hybrid system obtained an improvement in the impact strength， storage modulus， and loss modulus， indicating a reinforcing and toughening effect on the film. This also， accelerated the crystallization rate of the PE⁃HD/PP hybrid system and promoted the haze formation of the film. The film showed a haze of 80 % and a gloss of 7.8 % at a PE⁃HD content of 40 wt% in the visual layer along with an optimal matting effect. The film also presented the highest tensile strength of 29.5 MPa and the highest elongation at break of 64 % at a micron SiO₂ content of 3 wt% in the core layer. The film obtained a light transmittance of 58.8 %， and its haze increased to 82.3 %.

Key words: matting film, heat sealing, micron silicon dioxide, haze, three?layer cast co?extrusion