Process for recycling a metalized polyester film

Abstract

The present invention relates to a process for converting the waste or used metalized polyester (PET) film into recycled PET (RPET) as a starting raw material for various utility products. Particularly, the present invention provides a process for the manufacturing of high quality strapping or monofilament yarn or sheets from the recycled metalized PET film.

1 . A process of converting waste or used metalized polyethylene terephthalate (PET) film to obtain recycled metalized PET pellets suitable to produce PET straps, monofilament yarn, and PET sheets, the method comprising:
 (i) collecting waste or used metalized PET film;   (ii) obtaining crushed film or flakes by reducing the size of the waste or used metalized PET film by a grinder or granulator or by cutter compactor;   (iii) washing the film of step (i) and/or crushed film or flakes of step (ii) in a hot water bath or in an alkaline or alkali solution having a concentration in the range of 0.5 to 3% in water solution at a temperature of from room temperature to 90° C.;   (iv) densifying the film or flakes of step (iii) in an agglomerator to increase the bulk density of the film or flakes;   (v) feeding the thus obtained film or flakes of step (iv) into an extruder for devolatilizing, homogenizing, and converting the same into melt;   (vi) conveying the melt of step (v) into a pelletizer to obtain recycled metalized PET pellets having an intrinsic viscosity less than 0.60 dl/g; and   (vii) increasing the intrinsic viscosity of the pellets obtained in step (vi) to a value of up to 1.00 dl/g by solid state polymerization of the recycled metalized PET, wherein the thus obtained recycled metalized PET pellets are suitable for making high quality strapping or monofilament yarn or sheets.   
     
     
         2 . The process as claimed in  claim 1 , wherein the alkaline solution is a caustic soda having a concentration in the range of 1 to 2 wt./v % at a temperature of 60-85° C. 
     
     
         3 . The process as claimed in  claim 1 , wherein the metal in the metalized film is aluminum. 
     
     
         4 . The process as claimed in  claim 1 , wherein the thus obtained recycled metalized PET pellets of step (vii) are suitable for making high quality strapping or monofilament yarn or sheets that are made up of up to 100% of said pellets. 
     
     
         5 . A PET strapping or monofilament yarn or sheets produced from the recycled metalized PET pellets obtained by the process as claimed in  claim 1 .