A new prepolymer development programme, conducted by Huntsman Polyurethanes, has shown that it is technically possible to significantly improve the chemical and heat resistance of polyurea spray technologies. As opposed to the traditional approach, Huntsman scientists concentrated on modifying the isocyanate part of polyurea during research. The technical study at Huntsman involved how the isocyanate chemistry can positively influence the chemical performance and physical attributes of a final coating solution. Traditionally, technical teams have concentrated on re-engineering the resin component of a system - mainly because the raw materials on this side are much easier to handle. So far, polyurea have been recoginized less appropriate for chemical resistance and high temperatures applications vis-à-vis epoxy or polyester solutions. Huntsman's new development has proved significant to change the thinking.
During research trials, Huntsman tested four different systems. SUPRASEC® 2054, an established industry isocyanate was used as a benchmark. Three prototypes were developed from this prepolymer by adjusting molecular weight distribution, increasing chemical crosslinking and introducing different isomer structures to the MDI molecule. All four sprays were then applied under trial conditions and tested -- using industry standard solvents and environments -- for chemical resistance and mechanical and thermal properties. The initial results were striking. Huntsman found that modification of the MDI prepolymer, by selected prepolymerisation, can result in improved acid resistance and make a polymer more tolerant to high temperatures. It also discovered that modifications to the MDI structure can lead to improved resilience to solvent attack.