IMPROVED RECYCLE-CONTENT POLYESTER POLYOLS

摘要

Polyester polyols made from recycled polyethylene terephthalate (rPET) and processes for making them are disclosed. The rPET is heated with a C3-C10 glycol reactant to give a digested intermediate comprising glycols and a terephthalate component, which comprises 45 to 70 wt. % of bis(hydroxyalkyl)terephthalates, and preferably lesser amounts of terephthalate dimers and trimers. Treatment of the digested intermediate with activated carbon gives a polyester polyol having a color index less than 20. The polyols have desirable hydroxyl numbers, viscosities, appearance, and other attributes for formulating polyurethane products and are a sustainable alternative to bio- or petrochemical-based polyols.

主权项

1. A polyester polyol made by a process which comprises:
(a) heating a composition comprising recycled polyethylene terephthalate (rPET) with a C3-C10 glycol reactant to give a digested intermediate comprising glycols and a terephthalate component, wherein the terephthalate component comprises, by gel permeation chromatography using ultraviolet detection, 45 to 70 wt. % of bis(hydroxyalkyl)terephthalates; and (b) treating the digested intermediate with activated carbon under conditions effective to give the polyester polyol; wherein the molar ratio of C3-C10 glycol reactant to rPET is at least 2.0, and the polyester polyol has a hydroxyl number within the range of 25 to 800 mg KOH/g and a color index less than 20, where color index is defined by 100×(|a*|/L*) as measured by CIE colorimetric analysis.