Biaxially oriented polypropylene for printing of water-based inks and heat-sealing/non-heat-sealing electroplating treatment and process thereof

A process for manufacturing thermal-sealable biaxially oriented polypropylene film for electroplate, comprising:

• feeding a first mixture to a main extruder, said first mixture comprising polypropylene homopolymer (MFI 2-5, I.I 94-99%) and non-migrating additives or calcium stearate;
• feeding a second mixture to a first auxiliary extruder, said second mixture comprising 99-92% by weight of polypropylene homopolymer (MFI 4-9, melting point 120-145° C.) and 2-10% of polypropylene particles containing 1-8% by weight of non-migrating anti-adherent agent and calcium stearate, wherein the average diameter of the polypropylene particles is less than 4 μm;
• feeding a third mixture to a second auxiliary extruder, said third mixture comprises 99-92% by weight of polypropylene homopolymer (MFI 2-5, I.I 94-99% ) and 2.5-20% by weight of polypropylene particles containing 2-10% by weight of organic or inorganic anti-adherent agent, wherein the average diameter of the polypropylene particles is less than 4 μm;
• co-extruding the three mixtures through a T-shape die at an extruding temperature ranging from 200 to 280° C. to form a laminate wherein said laminate includes a lamina of said first mixture, a lamina of said second mixture and a lamina of said third mixture;
• cooling said laminate to a temperature ranging from 15 to 60° C. to form a sheet;
• heating said sheet to a temperature ranging from 120 to 155° C. to form a heated sheet;
• initially stretching said heated sheet 400% to 700% unaxially;
• cooling said heated sheet to form a cooled sheet;
• heating said cooled sheet to a temperature ranging from 150-190° C. to form a reheated sheet;
• stretching said reheated sheet 700% to 1000% in a direction perpendicular to said initial stretching to form a biaxially-stretched sheet;
• cooling said biaxially-stretched sheet;
• and
• treating said biaxially stretched sheet with a flame produced by combusting liquid natural gas (L.N.G.) and having a flame temperature ranging from 700-900° C., wherein said liquid natural gas contains more than 85% of methane and the thickness of said biaxially-stretched sheet ranges from 12-110 μm.

A process for manufacturing non-thermal-sealable biaxially oriented polypropylene film for electroplate, comprising:

• feeding a first mixture to a main extruder, said first mixture comprising polypropylene homopolymer (MFI 2-5, I.I 94-99%) and non-migrating additives or calcium stearate;
• feeding a second mixture to a first auxiliary extruder, said second mixture comprising 99-92% by weight of polypropylene homopolymer (MFI 2-5, melting point 120-145° C.) and 2-10% of polypropylene particles containing 1-8% by weight of non-migrating anti-adherent agent and calcium stearate, wherein the average diameter of the polypropylene particles is less than 4 μm;
• feeding a third mixture to a second auxiliary extruder, said third mixture comprising 99-92% by weight of polypropylene homopolymer (MFI 2-5, I.I 94-99% ) and 2.5-20% by weight of polypropylene particles containing 2-10% by weight of organic or inorganic anti-adherent agent, wherein the average diameter of the polypropylene particles is less than 4 μm;
• co-extruding the three mixtures through a T-shape die at an extruding temperature ranging from 200 to 280° C. to form a laminate wherein said laminate includes a lamina of said first mixture, a lamina of said second mixture and a lamina of said third mixture;
• cooling said laminate to a temperature ranging from 15 to 60° C. to form a sheet;
• heating said sheet to a temperature ranging from 120 to 155° C. to form a heated sheet;
• initially stretching said heated sheet 400% to 700% unaxially;
• cooling said heated sheet to form a cooled sheet;
• heating said cooled sheet to a temperature ranging from 150-190° C. to form a reheated sheet;
• stretching said reheated sheet 700% to 1000% in a direction perpendicular to said initial stretching to form a biaxially-stretched sheet;
• cooling said biaxially-stretched sheet;
• and
• treating said biaxially-stretched sheet with a flame produced by combusting liquid natural gas (L.N.G.) and having a flame temperature ranging from 700-900° C., wherein said liquid natural gas contains more than 85% of methane and the thickness of said biaxially-stretched sheet ranges from 12-110 μm.