What Is Polyurea?
Polyurea is a resin with a urea (urea) structure in its main chain and is obtained by polymerizing isocyanate and polyamine. Polyurea is mainly used as a lining material. Polyurea coats an object by mixing isocyanate and polyamine in a spray, discharging it, and causing a quick chemical reaction after coating. Polyurea has excellent chemical resistance, water resistance, and abrasion resistance, making it suitable for lining chemical plants and chemical tanks.
Polyurethane is a resin with a structure similar to polyurea. The structure of the main chains of both resins is different, and the C-N bonds of polyurea are easily hydrolyzed, whereas the C-O bonds of polyurethane are more easily degraded.
On the other hand, polyurethanes are more flexible than polyureas because the main chains of polyurethanes are more rotatable than those of polyureas.
Polyurea Applications
Polyurea is a resin with a urea (urea) structure in the main chain and is obtained by polymerizing aromatic or aliphatic amines and isocyanates.
The main application method is by spray, in which a spray mixture of the two aforementioned components is applied, and a coating is applied by causing a chemical reaction to proceed on the object.
The main application of polyurea is as a lining material. Due to its excellent waterproofing, chemical resistance, abrasion resistance, and various other physical properties, polyurea is used to protect surfaces such as chemical tanks, chemical plant equipment, liquid-proof dikes, pits, and waterways. In addition, polyurea coatings are also used on cars to improve texture and durability.
Formation Reaction of Polyurea
Polyurea is a polymer of isocyanate and amine. By changing the structure of the raw material monomer, it is possible to obtain polyurea resins with different physical properties. Typical isocyanate is 4,4′-diphenylmethane diisocyanate (MDI), and amine is polyetheramine.
In the spray application, isocyanate and amine are compressed, heated, and sprayed from the sprayer in a mixed state. Immediately after the heated mixture adheres to the object, it reacts, and polyurea is immediately formed and coated. The spray also has the advantage of having a low environmental impact because it does not contain volatile organic solvents (VOCs) such as toluene or ethyl acetate.
Polyurea and Polyurethane
Polyurethane is a resin similar to polyurea. Polyurethanes have urethane bonds obtained from the reaction of isocyanate and polyol. Urethane resins are used in a variety of industries, including textiles, paints, adhesives, and synthetic leather, because their properties, such as hydrophilicity and chemical resistance, can be changed by changing formulations and molding conditions.
However, polyurethanes are susceptible to degradation due to hydrolysis at the C-O site, and they are also degraded by oxidative reactions caused by light and heat.
The C-N bond of polyurea does not undergo hydrolysis, so polyurea is less susceptible to degradation than polyurethane. Also, polyurethanes tend to rotate their main chains more easily than polyureas in terms of molecular structure, so polyureas tend to be rigid and excellent at blocking substances, while polyureas tend to be more flexible.