Polar-Group Polyester Base Film for Stable Metal Layer Bonding

The patent modifies the chemical composition parameters of the polyester base film by incorporating specific ratios of polyethylene terephthalate (50-95 wt%), polybutylene terephthalate (5-30 wt%), and polyethylene naphthalate (5-20 wt%). This parameter optimization enhances the surface tension and chemical reactivity of the base film, thereby improving bonding strength with the metal layer while maintaining manufacturing feasibility through standard extrusion and stretching processes

The patent creates a composite polyester material system combining multiple polyester types (PET, PBT, PEN) in specific proportions. This composite approach leverages the complementary properties of each polyester component: PET provides structural stability, PBT enhances flexibility and bonding, and PEN improves thermal resistance. The synergistic combination achieves superior adhesion strength while maintaining ease of manufacture through unified processing

The patent optimizes the thermal parameters of the polyester base film by controlling the glass transition temperature (Tg) through selective polyester composition. The combined PET-PBT-PEN system achieves a balanced Tg range that provides sufficient thermal stability during physical vapor deposition (preventing excessive shrinkage) while maintaining adequate surface tension for strong metal layer bonding. The specific weight ratios of each polyester component are tuned to achieve this thermal-parameter optimization

The composite polyester structure combines materials with different thermal expansion coefficients and glass transition temperatures. PET provides high thermal stability, PBT adds flexibility with lower Tg, and PEN contributes intermediate properties. This composite architecture creates a buffer effect that dampens thermal shrinkage during deposition while preserving surface bonding characteristics, thereby simultaneously achieving strong adhesion and precise dimensional control