The Concept of Polyurethane and Polyester Coatings

The concept of polyurethane and polyester coatings
Polyurethane coatings and polyester coatings are relatively important types in the coatings industry. Although they are only a word difference, they are two different products. For industry insiders, the concepts of polyurethane coatings and polyester coatings have already been professionally unified, but outside the industry, especially in the process of product sales and promotion, these concepts are still vague.
1. Polyurethane coating
Polyurethane coating is the abbreviation of polyurethane coating, which refers to a coating containing a considerable number of urethane bonds in its paint film. Speaking of polyurethane coatings, we must first talk about the founder of polyurethane Otto Bayer. He invented polyurethane in 1937 and was also the founder of polyurethane chemistry. Since the 1950s and 1960s, Bayer has begun to use various monomers, as well as polymerized polyesters, polyethers, acrylates, and isocyanates, in polyurethane coatings.
The resin used in polyurethane coatings is not based on polyester resins or acrylic resins like polyester coatings and acrylic coatings. The resins used in polyurethane coatings are not polymerized by urethane monomers, but are made of polyisocyanate and Polyols are polymerized.
Polyurethane coatings have strong corrosion resistance, good weather resistance, and excellent various properties, especially the emergence of cross-linked two-component polyurethane coatings, coupled with environmentally friendly functions, so that polyurethane coatings have developed by leaps and bounds. , Widely used in woodware, construction, plastics, anti-corrosion, machinery and other fields, becoming one of the coating varieties with the fastest growth potential.
2. Polyester coating
In the traditional sense, polyester is an abbreviation for polymer compounds formed by polycondensation of dihydric alcohol or polyhydric alcohol and dibasic acid or polybasic acid, including polyester resin, polyester fiber, polyester rubber, etc., here only Talk about polyester resins related to coatings. According to the different raw materials used, polyester resins are divided into saturated polyester resins and unsaturated polyester resins.
The polyester coatings we usually refer to refer to coatings that use polyester resin as the film-forming material. According to the polyester resin classification described above, they are divided into two categories: saturated polyester coatings and unsaturated polyester coatings.
Saturated polyester resin is mainly linear polyester resin, which is formed by polycondensation of saturated dibasic acid and glycol. Of course, saturated polyester coatings use saturated polyester resins that do not contain unsaturated bonds and have active groups such as hydroxyl or carboxyl groups as the film-forming material, add amino resin or polyisocyanate as the curing agent, and heat to crosslink and cure to form a film. It has excellent film appearance, mechanical properties, and indoor and outdoor durability. It can be made into solvent-based, high-solid coatings, etc., and is widely used in coil steel materials, light industrial appliances, furniture and other industries.
Unsaturated polyester resins are mainly unsaturated linear polyester resins produced by unsaturated dibasic acids and diols, and the main chain of the molecule contains -C=C- double bonds. Unsaturated polyester coating is a coating made by dissolving unsaturated polyester resin in copolymerizable monomers.