CEH Report

Table of Contents

Abstract

Polyester polyols are macroglycols that are prepared by the condensation of a glycol and a dicarboxylic acid or acid derivative. The three general types of polyester polyols are manufactured from aliphatic diacids, aromatic diacids or caprolactone. Polyester polyols react with polyisocyanates in the manufacture of polyurethane polymers. The functionality, structure and molecular weight of the polyester polyols are varied to produce a range of polyurethane products. Polyester polyols compete with the more widely used polyether polyols; however, polyester polyols are preferred in some applications such as rigid foam boardstock because of their low cost and improved flame retardancy. In nonfoam polyurethane markets, such as elastomers, coatings, sealants and adhesives, advantageous properties include improved wear resistance, load bearing, heat aging, chemical resistance and UV stability. Generally, caprolactone-based polyols are higher-performance polyester polyols compared with other aliphatic polyester polyols, particularly in nonfoam applications. Pricing is higher than the typical aliphatic polyester polyols based on adipic acid.

The market for polyester polyols expanded rapidly between 2005 and 2008, before the economic crisis hit the chemical industry most dramatically in the fourth quarter of 2008. Global demand for polyester polyols grew from around 1.3 million metric tons in 2005 to 1.52 million metric tons in 2008, corresponding to an average growth of 5.4% per year during the 2005–2008 period. The most dynamic markets were China and Central and Eastern Europe. In terms of end uses, the demand for insulation (polyurethanes/polyisocyanurates) foam spurred demand for polyester polyols in the most developed industrial countries of North America and Europe.

The following pie chart shows world consumption of polyester polyols:

The polyester polyol business is a global one. COIM and Stepan are the largest producers. COIM produces aliphatic and aromatic products, with plants in Italy, Brazil, Singapore and the United States. Stepan has aromatic-based production sites in several locations—the United States, Germany and China.

The rigid foam polyurethane industry's move from HCFC-141b (banned in industrialized countries in 2003 and for spray foam applications in the United States after January 1, 2005) to water-blown, hydrofluorocarbon (HFC-245fa and HFC-365mfc) and hydrocarbon (pentanes and/or mixtures) blowing agents necessitated research on and development of new polyol products that would provide the required properties (including flame retardancy, insulation properties and foam stability) in the rigid foam markets. Recently, aromatic polyester polyols are being developed with lower hydroxyl (OH) numbers, which would require less MDI in the production of rigid polyurethane foam and polyisocyanurate foams consumed in laminate insulation.