Standard Group - Macromolecular Colorant|Copolymer Color Resin
Standard Group - Macromolecular Colorant|Copolymer Color Resin
What is powder coating?
time：2025-11-03 click：Powder coatings refer to a new type of solvent-free, 100% solid powder coating. They are characterized by being solvent-free, pollution-free, recyclable, environmentally friendly, energy-saving and resource-efficient, reducing labor intensity, and providing high mechanical strength of the coating film.
Powder coatings are completely different from ordinary coatings; they exist in the form of fine powder. Because they do not use solvents, they are called powder coatings. The main characteristics of powder coatings are: harmless, high efficiency, resource-saving, and environmentally friendly.
They are divided into two main categories: thermoplastic powder coatings and thermosetting powder coatings.
Thermoplastic powder coatings are composed of thermoplastic resins, pigments, fillers, plasticizers, and stabilizers. Thermoplastic powder coatings include: polyethylene, polypropylene, polyester, polyvinyl chloride, chlorinated polyether, polyamide-based, cellulose-based, and polyester-based.
Thermosetting powder coatings are composed of thermosetting resins, curing agents, pigments, fillers, and additives. Thermosetting powder coatings include: epoxy resin-based, polyester-based, and acrylic resin-based.
There are many classification standards, and the names of various powder coatings on the market vary considerably. They can be divided into two main categories based on the properties of the film-forming substance: thermoplastic powder coatings and thermosetting powder coatings. Alternatively, they can be classified by the appearance of the film-forming substance: matte, high-gloss, artistic, etc. They can also be classified by the application environment: indoor and outdoor.
While the variety of powder coatings is not as extensive as that of solvent-based coatings, there are still many polymer resins that can be used as powder coatings. They can be broadly classified into two categories: thermosetting and thermoplastic.
Thermosetting powder coatings refer to coatings that use thermosetting resins as the film-forming substance. With the addition of a curing agent that initiates a cross-linking reaction, they form an insoluble and infusible hard coating upon heating. Even at high temperatures, this coating will not soften like thermoplastic coatings; it will only decompose. Because thermosetting powder coatings use resins with low degrees of polymerization and low molecular weight, the coatings have good leveling properties and decorative properties. Furthermore, after curing, the low molecular weight prepolymers can form a network of cross-linked macromolecules, resulting in coatings with good corrosion resistance and mechanical properties. Therefore, the development of thermosetting powder coatings has been particularly rapid.
Due to their excellent adhesion to metals, corrosion resistance, hardness, flexibility, and impact strength, epoxy powder coatings were the first type of thermosetting powder coating to be used. Epoxy powder coatings are formulated with epoxy resin, curing agent, pigment, filler, and other additives. The contributions of these components to the performance of the resulting powder coating are mutually restrictive and influential; a suitable formulation is actually the result of the coordination of these components.
Polyester powder coatings have unique properties compared to other types of powder coatings. Polyester resin exhibits better weather resistance and UV resistance than epoxy resin. Furthermore, due to the polar groups in polyester resin, it has a higher powder application rate than epoxy resin, is less prone to yellowing during baking, has high gloss, good leveling properties, a full film, and light color, thus possessing excellent decorative properties. It is commonly used in refrigerators, washing machines, vacuum cleaners, instrument housings, bicycles, furniture, and other fields.
Acrylic resin powder coatings come in thermoplastic and thermosetting types. The biggest advantages of thermosetting acrylic resin powder coatings are excellent weather resistance, color retention, stain resistance, strong metal adhesion, and superior film appearance, making them suitable for decorative powder coatings.
Thermoplastic powder coatings first appeared in 1950. They melt at the spraying temperature and solidify into a film upon cooling. Due to the simplicity of processing and spraying methods, powder coatings only require heating to melt, leveling, and cooling or extraction to solidify into a film, without the need for complex curing equipment. Most of the raw materials used are common polymers available on the market, and they can meet the performance requirements under most conditions. However, some shortcomings exist, such as high melting temperature, low coloring level, and poor adhesion to metal surfaces. Nevertheless, commonly used thermoplastic powder coatings still exhibit some unique properties. Polyolefin powder coatings have excellent solvent resistance; polyvinylidene fluoride coatings have outstanding weather resistance; polyamides have excellent abrasion resistance; polyvinyl chloride (PVC) has a good price/performance ratio; and thermoplastic polyester powder coatings have the advantages of beautiful appearance and high artistic appeal. These characteristics make thermoplastic powder coatings occupy a large proportion of the coating market.
It is one of the cheapest polymers for large-scale industrial production. It has excellent solvent resistance, good resistance to water and acids, impact resistance, salt spray resistance, and can prevent food contamination. It also has high insulation strength for electrostatic spraying. It is mainly used for coating metal mesh, steel furniture, chemical equipment, etc.
It possesses excellent corrosion resistance, chemical resistance, and superior electrical insulation and UV radiation resistance. Its disadvantages include low mechanical strength and poor adhesion to the substrate. It can be used for chemical tanks, impellers, pumps, pipe inner walls, instrument housings, metal sheets, refrigerator inner mesh panels, automotive parts, etc.
Nylon, also known as polyamide, generally has a high melting point because the nitrogen atom in the chlorine group of its molecular chain easily forms hydrogen bonds with the hydrogen atoms in adjacent chain segments. Nylon has advantages such as high mechanical strength, impact resistance, hardness, wear resistance, low coefficient of friction, and low dust absorption, making it suitable for components with special requirements. Examples include water pump impellers, textile machinery parts, diesel engine starter piston parts, sailboat propeller impellers, automobile wheels, motorcycle brackets, agricultural machinery, construction and sports equipment, etc. Furthermore, due to nylon's resistance to salt water and its inertness to mold and bacteria, it is well-suited for manufacturing coatings that are immersed in or in contact with seawater. Nylon powder coatings are also non-toxic, odorless, resistant to mold, and do not promote bacterial growth, making them ideal for spraying components in the food industry, drinking water pipes, and food packaging.
Many types of fluoropolymers can be used to prepare powder coatings, such as polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PTFCE), and polyvinylidene fluoride (PVDF). PTFE has a high melting point of 327℃ and can be used long-term within a temperature range of -250 to 250℃. It also possesses excellent corrosion resistance, remaining uncorroded even in aqua regia, excellent dielectric properties, an extremely low coefficient of friction, and self-lubricating properties, earning it the nickname "King of Plastics." It is widely used in petroleum and chemical anti-corrosion coatings, seals, bearing lubrication materials, electronic and electrical materials, ship launching rails, and non-stick cookware coatings.
Polychlorotrifluoroethylene (PTFE) is cheaper than PTFE, allows for lower processing temperatures, and its coating can be used long-term below 130℃. Its resistance to alkali and hydrogen fluoride corrosion is superior to acid-resistant enamel, and its resistance to hydrochloric acid, dilute sulfuric acid, hydrogen chloride, and chlorine corrosion is superior to stainless steel equipment. It is widely used in corrosion-resistant equipment in chemical plants, pesticide plants, pharmaceutical plants, and detergent plants.
The biggest advantage of polyvinylidene fluoride (PVDF) powder coatings is their excellent weather resistance. They exhibit high resistance to degradation under outdoor exposure and do not attract dust, easily maintaining their original gloss. Chlorinated polyether powder coatings possess excellent chemical stability. The coating film exhibits good resistance to corrosion and dissolution by various acids, alkalis, and solvents, with chemical stability second only to PTFE. They also have good mechanical and abrasive properties. Chlorinated polyether powder coatings are mainly used in chemical equipment, pipe linings, and instrument housings. Their disadvantage is relatively poor adhesion to metals. Additives can improve this adhesion.
Latex powder is produced by spray drying an emulsion, and is mostly a vinyl acetate copolymer. Coatings made from latex powder are called latex powder coatings. They are mixed with water on-site and applied, making them the most environmentally friendly wall coating currently available.
4.1 Powder coatings are non-toxic, solvent-free, and free of volatile toxic substances. Therefore, they pose no risk of poisoning, fire, or the emission of pollutants, fully complying with national environmental protection laws.
4.2 High raw material utilization rate. Some well-known powder suppliers produce powders whose oversprayed powder can be recycled, with utilization rates reaching over 99%.
4.3 After pretreatment of the substrate, a single application without a primer is sufficient to achieve a thick film. This facilitates automated operation, resulting in high production efficiency and reduced costs.
4.5 The coating is dense, with good adhesion, impact resistance, and toughness, high edge coverage, and excellent resistance to chemical corrosion and electrical insulation properties.
4.5 Powder coatings are safe and convenient to store and transport.
Powder Coating Construction Process and Requirements: Electrostatic powder coating utilizes the principle of a high-voltage electrostatic corona field. A high-voltage negative electrode is connected to the metal guide at the spray gun head, and the workpiece being coated is grounded to form a positive electrode, creating a strong electrostatic field between the spray gun and the workpiece.
When compressed air, acting as the carrier gas, delivers the powder coating from the powder supply tank through the powder pipe to the guide rod of the spray gun, the corona discharge generated by the high-voltage negative electrode on the guide rod produces a dense negative charge in its vicinity. This causes the powder to acquire a negative charge and enter the high-intensity electrostatic field. Under the combined action of electrostatic force and the carrier gas, the powder is evenly applied to the surface of the grounded workpiece, forming a uniform powder layer, which is then heated and cured to form a durable coating film. Coating Application Process: Pretreatment → Drying (removing moisture) → Spraying → Inspection → Baking → Inspection → Finished Product.
5.1.1 To fully utilize the properties of powder coating and extend the service life of the coating film.
5.1.2 Inspect immediately after powder coating. If defects are found, address them promptly. If defects are found after curing, and are small and localized, not affecting the surface finish, they can be repaired by diluting the same color powder with acetone. If the defect is large and affects surface quality, sand it down, re-coat, or remove the coating with paint remover and re-powder coat.
5.1.3 Recycled powder must be screened to remove impurities before being mixed with new powder in a certain proportion.
Artistic powder coatings are characterized by their aesthetic appeal, strong three-dimensional effect, and good decorative properties, but their application process requires strict adherence to standards.
5.2.1 The input air pressure during powder spraying should not be too high, generally controlled between 1.5 and 3.5 kg/cm². Excessive air pressure will result in poor pattern clarity or pitting. The electrostatic voltage should also not be too high, generally controlled around 60-70 kV. Too high a voltage will cause the powder adhering to the workpiece surface to rebound, resulting in pitting, poor leveling, and other defects.
5.2.2 It is important to ensure the thickness of the powder coating during spraying, generally controlled between 70-100 μm, to facilitate the formation of clear and large patterns. A thin coating will result in indistinct and small patterns, and may also lead to pitting and exposed substrate.
5.2.3 Curing must be carried out at the specified temperature and time. If the temperature is too low or the time too short, the powder will not form patterns, and the mechanical properties will be greatly reduced due to incomplete curing. Furthermore, due to the special production process of artistic textured powder coatings, the pattern will become smaller or less noticeable after re-spraying with recycled powder. Therefore, it is generally recommended not to use recycled powder for artistic textured powder coatings. If it must be used, testing is necessary. As can be seen from the above, although the application requirements are stricter, it is believed that as long as the above factors are well controlled during the coating process, ideal and satisfactory results will be achieved.
It eliminates the need for various liquid chemical additives such as harmful film-forming, dispersing, wetting, leveling, anti-corrosion, and anti-mildew agents added to achieve the coating performance.
Ordinary coatings contain approximately 20-50% water or solvents, while powder coatings contain neither water nor solvents, being entirely solid. This makes transportation convenient and safe. Additionally, coatings containing water or solvents often freeze and damage when transported or stored at temperatures below 0℃, a problem that powder coatings do not have.
The largest growth areas in my country's powder coating market are the shipbuilding and pipeline industries. The existing problems are that impact resistance and moisture absorption need to be improved, and researchers are focusing their efforts on modifying various base materials. Domestically produced epoxy powder coatings for pipeline corrosion protection still lag behind high-quality foreign products in terms of storage stability and application properties.
Due to advancements in foreign automotive powder coating technology, automotive clear coats, wood coatings, and plastic coatings represent the most dynamic potential markets. The automotive industry will be a major consumer, with strong growth momentum in the powder coating markets of Greece, Turkey, and Eastern Europe. The Asia-Pacific region has even greater market potential and is considered the fastest-growing region globally.
Powder coatings are made by mixing special resins, pigments, fillers, curing agents, and other additives in specific proportions, followed by processes such as hot extrusion, crushing, and sieving. They are stable at room temperature and can be applied by electrostatic spraying, friction spraying (thermosetting method), or fluidized bed dip coating (thermoplastic method), followed by heating and baking to melt and cure, forming a smooth, glossy, permanent coating film to achieve decorative and corrosion-resistant purposes.
Electrostatic Spraying
Surface Treatment of Subject → Electrostatic Powder Coating → Melt-and-Level or Cross-linking Curing → Cooling → Product
9.1 To fully utilize the properties of powder coating and extend the service life of the coating film, the surface of the subject must first undergo rigorous pretreatment.
9.2 During spraying, the subject must be fully grounded to increase the spraying efficiency of the powder coating.
9.3 For subjects with significant surface defects, conductive putty should be applied to ensure a smooth and even coating.
9.4 After spraying, the object needs to be heated and cured. The curing conditions should be based on the technical specifications of the powder product, but the curing temperature and time must be fully guaranteed to avoid quality accidents caused by insufficient curing.
9.5 Inspect immediately after powder spraying.
9.6 Recycled powder must be screened to remove impurities before being mixed with new powder in a certain proportion.
9.7 The powder supply hopper, spray booth, and recovery system should be kept away from contamination by powders of other colors. Therefore, they must be thoroughly cleaned before each color change.
10.1 Keep away from fire and direct sunlight. Store in a well-ventilated place with a temperature below 35℃.
10.2 Avoid storing in places susceptible to contamination by water, organic solvents, oil, and other materials.
10.3 After use, powder coatings should not be exposed to air. Always cover or tightly seal the bag to prevent contamination.
10.4 Avoid prolonged skin contact. Wash off any powder adhering to skin with soap and water. Do not use solvents.
10.5 All equipment used in coating operations must be properly grounded to eliminate static electricity.
10.6 Avoid unauthorized discharge from the coating machine.
10.7 In the powder coating chamber, the concentration of suspended dust should be controlled below the safe concentration to avoid the risk of dust fire and explosion.
The above is some information about powder coatings. If you have any further questions, please contact us.
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