Types of Polyurea
At present, there are three branches in the family of polyurea materials, namely aromatic, aliphatic and aspartic esters, which account for 70%, 5% and 25% of the applications respectively.
1) Aromatic polyureas are synthesized by the reaction of Aromatic isocyanates (such as MDI, liquefied MDI, PAPI, etc.) with amino polyethers and chain extenders. They have the advantages of high strength and reasonable price. However, due to the existence of benzene ring in the system, anthracene, quinone and other colored groups are easily oxidized, and there is a certain degree of yellowing in the use process.
Applicable to anti-corrosion, wear resistance and other materials that do not require high decoration protection.
2) Aliphatic polyureas are prepared by the reaction of aliphatic isocyanates (such as HDI, HDI trimer, HMDI, TMKDI, etc.) with amino polyethers and alicyclic amine chain extenders. They have yellowing resistance, good corrosion resistance and excellent color retention, but their physical strength is slightly worse than that of aromatic polyureas. They can be used as decorative topcoatings for outdoor buildings and surface protection of aromatic polyurea coatings. Cover, but expensive.
3) Polyaspartic acid ester polyurea is a new generation of polyurea material developed successfully in recent years. It is prepared by reaction of aliphatic isocyanate and polyaspartic acid ester, which is quite different from conventional polyurea coatings in construction and coating performance, such as adjustable reaction speed, gel time can vary from several minutes to several hours; it can be constructed by high temperature and high pressure impact mixing equipment, or by ordinary spraying equipment, which can be cured at low temperature. It has the advantages of no yellowing of coating, no foaming during curing, thick coating construction and good adhesion to substrates.
