Method to reduce regenerated acetaldehyde in pet resin

摘要

There is disclosed a process for reducing the amount of acetaldehyde generated when polyethylene terephthalate (PET) chip is subjected to high temperatures in order to render the PET chip suitable for making food containers, particularly beverage bottles. This process comprises the addition of primary and secondary antioxidants either prior to or after the PET polycondensation reaction in order to reduce the amount of regenerated acetaldehyde produced by the polymer. The polyethylene terephthalate produced by this process reduces regenerated acetaldehyde by at least 25% in comparison to control resin produced without antioxidants, while maintaining suitable color for use as clear glass replacement. There is also disclosed a process for molding a PET preform wherein the polymer prepared as described above is melted, formed into the desired preform shape, and solidified by cooling. This preform can then be reheated above its glass transition temperature and molded into the desired container shape.