Process for separating polyethylene terephthalate from polyvinyl chloride

Abstract

Today there is a growing demand to recycle plastics including polyethylene terephthalate. Sources of polyethylene terephthalate for recycling often contain polyvinyl chloride. It is necessary to separate polyvinyl chloride from the polyethylene terephthalate before it can be recycled into useful products. This invention reveals a process for recovering polyethylene terephthalate flakes from a recycle stream containing polyethylene terephthalate flakes and polyvinyl chloride flakes which comprises: (1) treating the recycle stream with (a) at least one inorganic base selected from the group consisting of sodium hydroxide and potassium hydroxide and (b) at least one nonionic surfactant under conditions and for a time sufficient to decrease the contact angle of the polyethylene terephthalate flakes with water below a value of 25.degree. while maintaining the contact angle of the polyvinyl chloride flakes above a value of about 45.degree.; (2) adding the treated recycle stream to water, to form an aqueous mixture containing the treated polyethylene terephthalate flakes and treated polyvinyl chloride flakes; (3) agitating the aqueous mixture to allow the polyvinyl chloride flakes to come in contact with gas bubbles; (4) allowing the polyvinyl chloride flakes to float to the surface of the aqueous mixture and allowing the polyethylene terephthalate flakes to sink to the bottom of the aqueous mixture; and (5) removing the polyvinyl chloride flakes from the surface of the aqueous mixture and removing the polyethylene terephthalate flakes from the bottom of the aqueous mixture.

Dependencies are inferred from the claim text.