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What is epoxy powder coating?

Epoxy powder coating is one of several different types of powder coating available.

Choosing the right powder coating depends on what your intended purpose for it is.

Some types of powder coating are more durable than others, and some are more suited to external use than others.

Here, we explain what epoxy powder coating is, where and how to apply it, and how it compares to other powder coatings.

What Are Epoxy Powders?

Epoxy powders coating use epoxy resins within the powder coating mix.

Epoxy is an organic compound. It is made up of carbon chains that are linked to other elements, such as hydrogen, nitrogen or oxygen.

This type of link is a covalent bond. This chemical bonding is a link between atoms, through the electrostatic attraction of their nuclei.

Characteristic physical properties of covalent compound materials include lower melting points and electrical conductivity.

Consequently, epoxy powder coating has a good mechanical resistance and can stand up to various environmental challenges, including high temperatures.

Epoxy is created through the polymerisation or combination of resin hardeners with a catalyst, producing a material with mechanical and chemical strength.

Variations in the epoxy curing process leads to different properties in epoxies, which, when modified, can provide improved thermal insulation and thermal conductivity.

What Are the Benefits of Epoxy Powder Coating?

Epoxy powder coatings provide tough, durable and resilient coatings for metal. They are well-suited to applications where there is a requirement for a hard, electrical insulating coating, or where there surfaces will be subject to a wide range of temperatures.

  • Epoxy powders produce and exceptionally hard finish, which makes the surfaces they coat resistant to impact and abrasion.
  • Epoxy powder coating also provides an effective barrier against corrosion.
  • It is effective as a high dielectric insulator, when applied to copper or aluminium conductors, and is useful in reducing the need for time-consuming and expensive lamination processes.

Where Can You Use Epoxy Powder Coating?

Due to its resistance to corrosion and harsh chemical, epoxy powder coating is used as a metal protector for a wide variety of applications:

  • It coats pipelines, pillars and poles 
  • Epoxy powders protect steel rebars in high load bearing structures
  • Its anti-corrosion properties work for marine structures and vessels
  • Epoxy powder coating protects industrial furniture, for when it is exposed to aggressive cooling, and cleaning and lubrication fluids
  • Epoxy powder coating is applied to household goods such as washing machines, refrigerators, microwaves and stoves.

What are the Properties of Epoxy Powders?

  • Many epoxy powder coatings can be used at temperatures of 150°C or higher

  • In thicknesses over 10 mils (250 µm), they have a dielectric strength of up to 12,000 volts/mil
  • They are resistant to corrosion and to most solvents and mild acids
  • Epoxy powders have excellent adherence to metal substrates, and in many situations do not require a primer.

Are There Other Types of Epoxy Powder Coating?

As well as epoxy powder coating, there are also epoxy-polyester powder hybrid coatings.

These hybrids combine epoxy and polyester resins in a powder which retains many of the same characteristics as epoxy powder coating.

They do, however, contain a high proportion of polyester, sometimes over 50%.

These hybrid coatings are tough and durable, and are often competitively priced. They deteriorate more slowly than epoxy powder coatings when exposed to outdoor elements.

However, they may also be less resistant to chemicals and solvents compared to epoxy powders.

They are a popular choice for all round performance.

What Makes Epoxy Powder Coating Different?

There are two broad categories of powder coating:

  • Thermoplastic
  • Thermosetting

Both types of powder will melt when exposed to heat. However, thermoplastic powder coatings retain the same chemical composition under heat.

On the other hand, thermosetting powder coatings will also crosslink chemically when they melt and flow together.

This means that in thermosetting coatings, the finished coating has a different chemical composition to the coating in powder form.

Epoxy powder coating is a thermosetting coating.

Other thermosetting powders are:

  • Epoxy-polyester hybrids
  • Polyester TGIC
  • Urethane polyester
  • Acrylic

Thermoplastic powders include:

  • Polyester
  • Nylon
  • Polyvinyl chloride
  • Polyolefins
  • Polyvinylidene fluoride

Thermosetting powders like epoxy are heat stable and, unlike thermoplastic powders, will not revert back to a molten stage if they are reheated after coating.

They account for the majority of powder coatings on the market.

How Do You Apply Epoxy Powder Coating?

As with other powder coatings, the usual way to apply epoxy powder coating is with an electrostatically-charged spray gun.

The gun charges the powder as it passes through the spray head, creating an opposite charge to the substrate of the part being sprayed. This makes the powder adhere to it.

You then bake the sprayed part in an oven. Powder coating melts at temperatures between 140°C and 220°C. This starts a curing process as the reactive components in the powder melt and flow together.

Once the powder coating has melted, fused, cooled then hardened, it leaves a tough, uniform film on the substrate it has coated.

Environmentally Friendly Coatings

Epoxy powder coatings are non-hazardous and easy to both transport and dispose of without causing environmental damage.

They are also highly economical with waste, since any powder you overspray you can recover and re-use.

For more information about epoxy powder coating and its many applications, please contact us.

 


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What is epoxy powder coating?

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