The difference between thermosetting and thermoplastic powder coatings
Thermosetting refers to the heating can be cured cross-linked, cross-linked coating does not melt or dissolve, there is a chemical reaction during the heating process. Thermoplastic refers to the heating of the powder can soften, but will not cross-link, the heating process only physical changes without chemical reactions. Specific performance differences are as follows.
Thermoplastic powder coating is the emergence of 1950, it melts at the spraying temperature, and solidifies into a film when cooled. Due to the simple processing and spraying method, powder coatings only need to be heated and melted, leveled, cooled or extracted to solidify into a film, without the need for complex curing devices. Most of the raw materials used are common polymers in the market, and most of the conditions can meet the requirements of the use of performance. However, there are some shortcomings, such as high melting temperatures, low coloration levels, and poor adhesion to metal surfaces. Nevertheless, the commonly used thermoplastic powder coatings still exhibit some unique properties, including polyolefin powder coatings with excellent solvent resistance; polyvinylidene fluoride coatings with outstanding weatherability; polyamide with excellent abrasion resistance; polyvinyl chloride with a good price/performance ratio; thermoplastic polyester powder coatings with beautiful appearance, high artistic advantages. These characteristics make thermoplastic powder coatings occupy a large proportion in the coatings market.
Thermosetting powder coating refers to the thermosetting resin as the film-forming material, adding the cross-linking reaction of the curing agent can form a hard texture of insoluble and non-melting coating after heating. The coating will not soften at higher temperature like thermoplastic coating, but only decompose. As the resin used in thermosetting powder coating is a low polymerization degree of prepolymer, low molecular weight, so the leveling of the coating is better, with better decorative, and low molecular weight of the prepolymer after curing, can form a network of cross-linked macromolecules, so the coating has good corrosion resistance and mechanical properties. Therefore, the development of thermosetting powder coatings is particularly rapid.