Study on the pretreatment process for the recycling of PDMS-coated PET film waste

Abstract

Polyethylene terephthalate (PET) film is a functional film with various protective properties such as its thermal stability, dimensional stability, high tensile strength, chemical stability, transparency, and gas impermeability. PET film usually composed of multiple layers to enhance the physical properties and grant various functionality. One of the commonly widely used PET film is polydimethylsiloxane (PDMS) coated PET film, which is widely used as a release liner to protect the surface of commercial products such as optically clear adhesive (OCA), wafer, flat panel display and printed flexible circuit because PDMS has excellent release properties such as hydrophobic surface, electrical insulation, flexibility, thermal stability and chemical stability. However, recycling of PDMS-coated PET film is difficult unless PDMS layer is removed from the PET film. In this work, a pretreatment process for removal of PDMS layer from the PET film by physical detachment of swollen PDMS is proposed. As the result, the amount of PDMS on the surface of PET film was decreased to 1%, suggesting that PDMS layer was successfully removed from PET film. As a result of glycolysis of pretreated film, the yield of bis(2-hydoxyethyl terephthalate) (BHET) was 85.24%. Pretreatment enables the recycling of PDMS-coated PET film waste.