The debate over the advantages of polyurea and polyurethane

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In 1937, Dr. Otto Bayer of the German company Farbenfabrik (the predecessor of Bayer) synthesized polyurethane using isocyanates, thus pioneering polyurethane technology. From the 1940s to the 1960s, polyurethane technology developed rapidly. In the 1970s, JEFFAMINE, a patented product of the American company Jefferson Chemicals, a terminal amino polyether, was introduced and was initially used as an epoxy curing agent. In the 1970s, spray polyurethane (urea), abbreviated as semi-polyurea, was developed based on spray polyurethane technology and amino-terminated polyethers. The use of amino-terminated polyethers to replace part of the hydroxyl-terminated polyethers as the R (resin) component thereby increases the reaction rate and improves the physical properties of the elastomer. In the 1970s and 1980s, research on Reaction Injection Molding (RIM) technology was first conducted in Germany and the United States, leading to its industrialization. Polyurea technology evolved from reactive injection molding; it builds on the principle of high-pressure impact mixing used in RIM to enable rapid spray molding. Germany and the United States are the birthplaces of spray elastomer technology. In 1986, Dudley J. Primeaux, a chemist at the American company TEXACO (now known as HUNTSMAN), and his team were the first to develop spray-applied polyurea elastomer materials. These materials were put into commercial use in North America in 1991, for protecting concrete surfaces, preventing corrosion of steel surfaces, and providing wear-resistant linings for pickup trucks. Spray polyurea technology is a branch of polyurethane technology; it represents the continuation and development of polyurethane and semi-polyurea technologies. In the United States, polyurea is classified as the 5th category of polyurethanes, representing a new product with excellent performance. The emergence of new polyurea technologies relies on breakthroughs in two key technologies: one is the successful development of amino-terminated polyethers and amino-terminated chain extenders ； Second is the successful development of high-pressure impact mixing equipment. Represented by the Polyurea Development Association (PDA) of the United States, there is strong advocacy for \"pure polyurea\". It is believed that \"pure polyurea\" has high reactivity, no tendency to foam, and delivers high-quality coatings ； No catalyst added; excellent durability ； It has a fast reaction speed, is insensitive to temperature and humidity, and can be applied below 0°C and in high-humidity conditions ； It is a \"universal paint\" with perfect performance. Represented by the European polyurethane giants, they prefer polyurethane and refer to half-polyurea as modified polyurethane. It is believed that semi-polyurea and polyurea are members of the polyurethane family; they represent a branch of polyurethane technology and are its continuation and development. Polyurethanes, semi-polyureas, and polyureas each have their own technical characteristics; it is necessary to make use of their strengths while avoiding their weaknesses. Each of them has its own areas of application, and efforts should be made to promote the common development of all three. Currently, wear-resistant and corrosion-resistant polyurethane spraying materials have been introduced from abroad. These materials are actually modified semi-polyureas that combine the advantages of polyurethane and polyurea, offering excellent wear and corrosion resistance as well as resistance to erosion and abrasion. More importantly, the adhesive used in conjunction with it has excellent properties. It maintains an extremely strong adhesion to the substrate surface even after prolonged exposure to impacts and mechanical forces, ensuring that the coating does not peel off when the linear velocity of the components in liquid or semi-liquid media is less than 28.5 m/s. It can be successfully applied in such complex dynamic working environments, offering very promising prospects for further development. The Shore hardness of this wear-resistant coating varies widely. It ranges from Shore A45 to Shore D60. The hardness can be adjusted according to different operating conditions; by increasing the content of polar groups, hydrogen bonds are utilized to enhance the intermolecular forces, thereby effectively extending the effective lifespan of the coating. Furthermore, this material can not only effectively resist erosion and cavitation wear, but also withstand corrosion from strong acids and strong bases within a pH range of 3-11. This material not only protects machine components from water-induced wear and cavitation erosion, but also shields them from corrosion caused by acidic and alkaline substances. It can truly be regarded as a versatile surface treatment material. This material boasts strong versatility and is widely used in various industrial fields that require corrosion- and wear-resistant protection, achieving excellent results. It has been proven that this material bonds very firmly to the substrate, and the lifespan of the coating is generally more than ten times longer than that of ordinary metal materials, resulting in significant economic benefits.