Polypropylene composite films by vacuum deposition process
Biaxially oriented polypropylene film with vacuum-deposited coating on aluminium composite film, and film is widely used for packaging purposes. However, generally resulting from a process of such films is easy to wear or peel, especially at high temperature and high humidity in summer, the aluminium coating are easier to peel. To solution this a problem, can in two-way stretch of polypropylene film Shang again laminated composite Shang a layer vinyl-propylene copolymer real (which vinyl components for 5~50%), then Yu nitrogen atmosphere in the on film surface for electric Halo processing, makes film surface of rough degrees and nitrogen carbon than (nitrogen atomic number/carbon atomic number) improve, such conducive to vacuum deposition of plating aluminum layer firm to bond in film of surface Shang. The process is as follows.
Melting index for 2G/10min of polypropylene and melting index for 5G/10min of propylene-vinyl copolymer real (vinyl content for 30%) respectively with two Taiwan extrusion machine Yu 270 ℃ Xia total extrusion have composite film, will its surface temperature cooling to 45 ℃ following, then again heating to 125 ℃, along longitudinal stretch 4.5 times times, again warming to 160 ℃, along horizontal stretch 9 times times, thereafter in horizontal relaxation 5% of conditions Xia, Yu 160 ℃ for hot stereotypes processing, then slowly cooling, Get the thickness of 0.035mm thin film which thickness of 0.032mm layer of polypropylene. Placed in a nitrogen atmosphere of this film, to current density in thin films of 1000~6000J/m2 Propylene-ethylene copolymers of corona discharge treatment on surface. Then adjust the power, surface nitrogen and carbon is 0.041. Processed film in the corona discharge treatment on the surface of aluminum, three-layer composite film, the thickness of the aluminum coating to 600A. The adhesion of the film better, surface gloss is 35, aluminium membrane adhesive strength for 4.5-5, bond strength grading of limits (5 is best, 1 the worst).