Making Polyurethane Adhesives with Renewable Polyols
- Apr 18, 2012
Though crude oil is rightly the ultimate source of many chemicals the adhesive industry uses, renewable alternatives can offer an alternative to aid economic and supply sustainability. To this end, how to produce polyol monomers from plants that can be used to make polyurethane adhesives has been broadly explored. Today, such monomers are commercially available, but their differences from conventional monomers can be an important consideration during formulation. Particularly important concerns include reactivity, cost and crystallinity. The most common and cheapest sources of renewable polyols are plant oils, which are triglyceride esters of saturated and unsaturated fatty acids. Castor oil in particular is a triglyceride of ricinoleic acid, a fatty acid that contains secondary hydroxyl groups that can be used produce polyols. Other natural oils, such as soybean oil, can be made into polyols by epoxidation at their unsaturated sites, for example. The resulting epoxy group can then be opened to produce secondary alcohols.