Ichiro Yoshihara

Coating resins synthesized from recycled PET

PET bottles collected from the Japanese market have been increasing year by year. In 2000, a total of 124,873 t of PET bottles were collected for reprocessing. Reprocessed PET is called recycled PET (hereinafter called R-PET), and 68.575 t of R-PET was used as raw materials for fibers, sheets, and various other uses in 2000. Regarding R-PET as a condensation polymer composed of ethylene glycol (EG) and terephthalic acid (t-PA), we have tried to utilize it in coating resin syntheses. Polyesters for powder coatings synthesized from R-PET in place of EG and t-PA showed the same structure and characteristics as a conventional polyester synthesized from ordinary EG and t-PA monomers. An alkyd resin for ambient temperature curing coatings was synthesized from R-PET as a substituent for EG and phthalic anhydride (PA). After modifying its monomer composition, it finally showed the same characteristics as the original resin. The use of R-PET in alkyd and polyester resin syntheses provides a beneficial means for mass consumption of R-PET.