Powder Coated Aluminum Baffles: Coating Performance Comparison for Indoor and Outdoor Applications

Powder coating is the most commonly used surface treatment method for aluminum baffles, with advantages of rich colors, strong decorativeness, moderate cost, environmental protection, etc. More than 90% of indoor aluminum baffles adopt powder coating, and more and more outdoor projects also use weather-resistant powder coating. However, the performance of different types of powder coatings varies greatly. Many users cannot distinguish between indoor powder and outdoor powder, misuse indoor powder for outdoor projects, leading to premature aging, fading, falling off of coatings, causing losses. This article introduces the performance and applicable scenarios of different powder coatings in detail.

The principle of powder coating is electrostatic spraying. Powder coatings are charged by high-voltage electrostatic guns and then adsorbed on the surface of grounded aluminum profiles, then enter the curing oven to cure and level at 180-200℃, forming a uniform coating. Powder coatings contain no solvents, 100% solid content, almost zero VOC emissions, good environmental performance, coating thickness is usually 60-120μm, thicker than liquid spraying, good impact resistance and wear resistance. The main types of powder coatings are ordinary polyester powder, weather-resistant polyester powder (also called super weather-resistant powder), fluorocarbon powder, with performance and price increasing in turn.

Ordinary polyester powder is the most commonly used powder for indoor aluminum baffles, main raw material is polyester resin, cheap, rich colors, good decorativeness, high coating hardness, wear and impact resistance, but weather resistance is general, easy to chalk, fade, lose gloss under ultraviolet irradiation. The artificial accelerated aging time of ordinary polyester powder is usually 250-500 hours, that is, obvious fading and chalking will appear after 1-2 years of natural outdoor exposure, gloss retention rate is lower than 50%, so it can only be used indoors, not outdoors. For indoor use, the service life of ordinary polyester powder can reach more than 10 years, fully meeting indoor use requirements, and there are many color choices, almost all RAL color card colors can be made, there are also various effects such as frosted, sand grain, high gloss, matte, metallic powder, etc., cheap, is the first choice for indoor ceilings.

Weather-resistant polyester powder, also called super weather-resistant powder, improves the formula on the basis of ordinary polyester powder, adopts polyester resin with better weather resistance and ultraviolet absorber, weather resistance is greatly improved, artificial accelerated aging time can reach 1000-1500 hours, gloss retention rate can keep above 70% after 5-8 years of natural outdoor exposure, fading grade is not lower than grade 2, basically meeting outdoor use requirements. The price of super weather-resistant powder is 30%-50% higher than ordinary polyester powder, but much cheaper than fluorocarbon spraying, suitable for outdoor projects with not particularly high weather resistance requirements, or outdoor parts not completely exposed to sunlight such as awnings, cornices. Now many exterior wall projects and old renovation projects in third and fourth tier cities will choose super weather-resistant powder, with high cost performance, more color choices than fluorocarbon, good decorative effect. It should be noted that the quality of super weather-resistant powder varies greatly, super weather-resistant powder from small factories may have worse weather resistance than ordinary polyester from large factories. When choosing, be sure to choose powder of well-known brands, such as AkzoNobel, Tiger Powder, Nippon, etc., and require weather resistance test reports.

Fluorocarbon powder is the most weather-resistant powder coating, main raw material is polyvinylidene fluoride (PVDF) resin, PVDF content not less than 70%, weather resistance is equivalent to liquid fluorocarbon spraying, artificial accelerated aging time can reach more than 3000 hours, gloss retention rate above 80% after 10-15 years of natural outdoor exposure, no chalking, no fading, no falling off, fully meeting long-term outdoor use requirements. The price of fluorocarbon powder is 2-3 times higher than ordinary polyester powder, equivalent to liquid fluorocarbon spraying price, but powder utilization rate is high, environmental performance is good, coating is thicker and more wear-resistant, which is the development direction of surface treatment for outdoor aluminum baffles. Fluorocarbon powder has relatively fewer colors, mainly common solid colors and metallic colors, special colors need to be customized, but with the development of technology, colors are becoming more and more abundant.

Many users think that powder coating can only be used indoors, not outdoors, which is a wrong concept. Ordinary polyester powder really cannot be used outdoors, but super weather-resistant powder and fluorocarbon powder can be used outdoors completely, performance is even better than ordinary liquid polyester spraying. Advantages of powder coating for outdoor use: first, thick coating, usually 80-120μm, twice as thick as liquid spraying, good wear and scratch resistance; second, environmental protection, no solvent emissions, meeting environmental requirements; third, uniform coating, no defects common in liquid spraying such as sagging, pinholes; fourth, high utilization rate, powder can be recycled, low cost.

Methods to identify indoor powder and outdoor powder: first, look at the test report, require the manufacturer to provide artificial accelerated aging test report of the coating, judge which kind of powder according to aging time; second, look at the price, processing fee of ordinary polyester powder coating is usually 15-25 yuan per square meter, super weather-resistant powder is 30-45 yuan per square meter, fluorocarbon powder is 60-80 yuan per square meter, if the price is significantly lower than market price, it must be ordinary polyester pretending to be outdoor powder; third, look at the sample, expose the sample to the sun for a few months, ordinary polyester powder will obviously discolor and lose gloss, super weather-resistant and fluorocarbon powder basically have no change; fourth, look at the powder brand, regular manufacturers will tell you what brand of powder they use, small factories often equivocate.

Precautions for using powder coated aluminum baffles: first, ordinary polyester powder for indoor use should not be used outdoors, otherwise it will fade and chalk in 2-3 years; second, for outdoor use, be sure to choose super weather-resistant or fluorocarbon powder, do not use ordinary polyester to save money; third, do not scratch the powder coated surface with sharp objects, although it is wear-resistant, sharp objects can still scratch the coating; fourth, use neutral detergent when cleaning, do not use strong acid and alkali detergents to avoid corroding the coating; fifth, try not to tear off the protective film during installation, tear it off before completion acceptance to avoid scratching the surface during installation.

To sum up, indoor ceiling aluminum baffles choose ordinary polyester powder, with highest cost performance and rich colors; outdoor cornices, awnings, low-rise building exterior walls choose super weather-resistant polyester powder, with high cost performance and weather resistance meeting requirements; high-rise building exterior walls, coastal areas, high corrosion environments choose fluorocarbon powder, with long service life and reliable quality. Choosing suitable powder coating according to use environment can not only ensure service life, but also reduce cost.