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Although the variety of powder coatings is not as numerous as solvent-based coatings, but can be used as powder coatings polymer resins are also many. The total can be divided into the thermostation type and thermoplastic type two categories.
1. Thermoclytic powder coating
refers to the thermosolytic resin as a film-forming substance, the curing agent added to the cross-linking reaction after heating can form an insoluble hard coating of the texture . The coating does not soften like a thermoplastic coating at a higher temperature, but only breaks down.
Because the resin used in thermoset powder coating is a pre-polymer with a lower polymerization and a lower molecular weight, the coating has better leveling, good decoration, and the pre-polymer of low molecular weight can form a mesh cross-linking large molecule, so the coating has better corrosion resistance and mechanical properties. Therefore, the thermoo-solid powder coatings are developing particularly rapidly.
1.1 epoxy powder coating
is the first variety to be used in thermosoated powder coating due to its excellent bonding with metals, corrosion resistance, hardness, flexibility and impact strength. Epoxy powder coatings are made up of epoxy Resin, curing agents, pigments, fillers, and other additives. The contribution of these components to the performance of the formed powder coating is mutually restricted and affected, a suitable formula, in fact, the result of the coordination of various components.
1.2 polyester powder coatings
polyester powder coatings are unique in nature compared to other types of powder coatings. The performance of weather resistance and ultraviolet light resistance is better than epoxy resin. In addition, because polyester resin with polar groups, so the powder rate is higher than epoxy resin, baking process is not easy to yellow, high gloss, good leveling, paint film plump, light color and other characteristics, so it has a good decorative. Generally used in refrigerators, washing machines, vacuum cleaners, instrument casings, bicycles, furniture and other fields.
1.3 acrylic powder coatings
acrylic powder coatings have thermoplastic and thermosolytic. The biggest advantage of thermoo-solid acrylic powder coating is that it has excellent weather resistance, color preservation, pollution resistance, strong metal adhesion, excellent appearance of coating film, suitable for decorative powder coating.
2. Thermoplastic Powder Coatings
Thermoplastic Powder Coatings were first developed in 1950 and dissolve at spray temperature and solidify into film when cooled. Due to the simple processing and spraying methods, powder coatings can only be heated to melt, level, cool or extract solidified into a film, without the need for complex curing devices. Most of the raw materials used are common polymers on the market, and most conditions meet the requirements of performance.
there are some shortcomings, such as high melting temperature, low coloration level, and poor adhesion to metal surfaces. Nevertheless, the commonly used thermoplastic powder coatings still show some unique properties, among which polyolefin powder coatings have excellent solvent resistance, polyfluoroethylene coatings have outstanding weather resistance, polyamide has excellent wear resistance, PVC has a better price/performance ratio, thermoplastic polyester powder coatings have the advantages of beautiful appearance, high artistry. These properties make thermoplastic powder coatings a large part of the coatings market.
2.1 PVC powder is one of the cheapest polymers mass produced in industrialization
it has excellent solvent resistance, good corrosion resistance to water and acid, good impact resistance, salt spray resistance, prevent food contamination and high insulation strength for electrostectric spraying. Mainly used for coating metal mesh, steel furniture, chemical equipment and so on.
2.2 polyethylene powder coating has excellent corrosion resistance
chemical resistance and excellent electrical insulation and UV radiation resistance. The disadvantage is that the mechanical strength is not high and the adhesion to the substring is poor. Can be used in chemical tank grooves, imperfles, pumps, pipe walls, instrument housings, metal plates, refrigerator in-net plates, automotive parts and so on.
2.3 nylon powder coating
Nylon, also known as polyamide, because the chlorine-based N atoms on the molecular chain and the hydrogen atoms on the adjacent chain segment easily form hydrogen bonds, so the melting point of polyamide resin is generally higher. Nylon has the advantages of high mechanical strength, impact resistance, hardness, wear resistance and small coefficient of friction, low vacuuming, etc., and can be used in specially requested components.
such as pump imperfles, textile machinery parts, diesel engine starting piston parts, sailboat thruster imperms, automotive wheels, motorcycle supports, agricultural machinery, construction and sports equipment. In addition, due to nylon's salt water and inertness to mold and bacteria, it is suitable for manufacturing coatings immersed in or in contact with seawater, while nylon powder coatings are non-toxic, tasteless, not eroded by mold, will not promote bacterial growth, and are suitable for spraying parts of the food industry, drinking water pipes and food packaging.
2.4 fluorine resin powder coatings
Fluoropolymers are able to prepare a wide variety of powder coatings, such as Teflon (PTFE), Teflon (PTFCE), polyfluoroethylene (PVDF) and so on.
Teflon melting point of up to 327 degrees C, can be used in the range of -250 to 250 degrees C for a long time, in addition to excellent corrosion resistance, even in king water does not corrode, excellent dielectic properties, very low coefficient of friction and self-lubrication, so known as the "plastic king."
a large number of applications in petroleum, chemical anti-corrosion coating, sealing, bearing lubrication materials, electrical and electronic materials, marine water rails and non-stick pot coating. PVC is cheaper than PTFE, processing temperature can be reduced, coating can be used for a long time below 130 degrees C, alkali and hydrogen fluoride corrosion resistance is better than acid enamel resistance, hydrochloric acid, sulfuric acid, hydrogen chloride and chlorine corrosion resistance is better than stainless steel equipment. Has been widely used in chemical plants, pesticide plants, pharmaceutical plants, detergent factories and other anti-corrosion equipment.
advantage of polyfluoroethylene powder coating is excellent weather resistance, high degradation resistance in outdoor exposure, and dust absorption, it is easy to maintain the original luster.
2.5 chlorinated polyether powder coating
chlorinated polyether has excellent chemical stability, coating film for a variety of acids, alkalis and solvents have good corrosion resistance, anti-solubility properties, chemical stability is second only to Teflon, mechanical and frictional properties are also very good. Chlorinated polyether powder coatings are mainly used in chemical equipment, pipe lining, instrumentation equipment shell and so on. The disadvantage is poor adhesion with metal. Additives can be added to improve adhesion with metals.
2.6 latex powder coating
latex powder is the emulsion dried by spray, most of which is currently ethylene acetate co-polymer. Paints produced with latex powder are called latex powder coatings. On-site water mixing construction, is currently the most environmentally friendly wall paint paint.