Powder coatings provide a versatile, durable solution for offering protection to a range of substrates. There are two broad categories of powder coating, thermoplastic and thermoset. Within these categories are several types of powder coating.
In addition, there are also applications for powder coatings that are specially formulated for metallic surfaces, including aluminium powder coating and zinc powder coating.
Thermoplastic powder coatings are manufactured from synthetic materials. They are synthesised through plants and transformed through chemical processes.
Thermoplastic powder coatings include:
Thermoplastic powder coatings can be especially effective when it comes to protection from wear and tear and providing chemical resistance.
They are less effective, however, for heat resistance, because high temperatures can melt thermoplastics.
PVC powder coatings are good for various forms of insulation.
Polyolefin powder coatings are highly resistant to abrasion and to chemicals. They provide a smooth finish and adhere well to substrates.
Nylon powder coatings are ideal for moving parts such as gears and conveyor belts because nylon has a low friction co-efficient. Nylon coatings are also hard-wearing and impact-resistant.
Thermoset powder coatings are based on a reaction between two or more components, known as cross-linking.
When you bake thermoset powder coatings, this cross-linking chemical reaction is non-reversible, altering the physical properties of the powder coating.
These thermosets will typically cure harder than thermoplastics, and provide a high level of resistance to heat.
Thermoset powder coatings include:
Epoxy powder coatings are tough and good electrical insulators, but are brittle if exposed to UV light.
The use of Epoxy-Polyester hybrids softens the epoxy coating, making it less likely to crack, and have better weathering properties, with less likelihood of chalking over time.
Polyester powder coatings are very much multi-purpose. They are widely used on outdoor surfaces, including building exteriors and several car parts.
Acrylic powder coatings are good for UV light resistance and leave a high-gloss finish, making them more attractive for decorative purposes.
Silicon-based powder coatings are the most heat-resistant of powder coatings, able to withstand temperatures exceeding 500°C. They are also very hard-wearing.
The most popular application for powder coating is to provide an external finish to products and objects that are made of metal.
Powder coating is used for external architectural features on many buildings, and it provides a protective to street furniture such as road signs.
Car parts that receive a lot of use, such as door handles and bumpers, are powder coated. It also provides a finish to wheel trims.
Powder coating protects agricultural and industrial machinery, and applies an attractive and durable finishing coat to individual consumer items such as golf carts and outdoor furniture.
Zinc rich powder coating is used on steel substrates, primarily as an anti-corrosive primer.
It forms a strong base layer that helps the finished surface be resistant to corrosion and chemicals.
Because it is a primer powder coating, you can then add layer subsequent layers of paint over it, to get the required finish.
Zinc rich powder coating is an epoxy-based, thermoset powder coating,
Zinc powder coating is usually an under-coat, though it may also act as a stand-alone coating if the surfaces it is applied to are for internal use.
Using this type of multi-coat system offers a high degree of protection for steel fabrications and other objects and parts.
The zinc rich coating protects vulnerable points especially, such as sharp edges, corners and hollow sections.
Polyester powder coating provides protection to aluminium surfaces. It also has a decorative quality, ensuring the finishing on aluminium substrates looks good too.
Standard polyester coatings can provide up to thirty years of UV resistance and protection from corrosion and humidity, while super durable powders offer longer lasting durability and resilience.
Aluminium powder coating is widely used in the automotive industry, in architectural projects and the construction industry, and on various consumer items and domestic appliances.
The powder coating process is economical and efficient, applied via an electrostatically charged spray.
This ensures the powder coating adheres to the prepared aluminium surface, before baking and curing.
Once heated to its optimum temperature, the powder melts together and forms an even film over the surface to which it has been applied.
The main components of powder coating are some form of resin, such as polyester or epoxy. Added to these are paint pigments, to provide different colours.
Other ingredients include additives. These serve various purposes. Some will provide a matt effect, while others will help to create a hardened finish.
An example of this is benzoin, which, when added to the epoxy resin used in thermoset powder coatings, will reduce its melt viscosity and surface tension.
Post additives help to prevent powder coatings from caking; and extenders or fillers add extra durability to them.
For more information about different types of powder coating, and how they can best meet your requirements, please contact us.