What Are the Types of Coil Coating

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In the mid to late 1930s, Joseph Hunter, the founder of Hunter Engineering, installed the first coil painting line. He used this method to paint the shutters as part of a continuous strip. Later, Hunter Engineering went on to design and build more coil coating lines. It was eventually acquired by the Italian global engineering company FATA Spa, which is known for building coating lines all over the world.

Today, the coil coating process offers a wide range of opportunities for the world's coating companies. The coil coating process is like one of those giant printing presses that produce evening newspapers. The process does not stop, it runs at a constant speed and the metal coils are constantly spliced together so that the moving web can be infinitely long.

What is the coil coating process?

According to EN-10169:2012-06, the coil coating process is a method of applying a continuous coating of organic coating material to a rolled metal strip substrate. The process consists of:

• Unrolling and cleaning of the coil, if necessary
• Chemical pre-treatment of the metal surface (one or both sides)
• Single or multiple applications of (liquid) paint or coating powder, followed by curing or lamination with plastic film
• Cooling and rewinding of the same coils for transport to the cutter, slitter, or manufacturer

Key coating types used in the coil coating process

The two main types of coatings used for coil coating are:

• Liquid coatings
• Powder coatings

Litong offers different types of coil coating to meet various aesthetic requirements. In addition, films are used instead of lacquers or additional lacquers where a very high aesthetic quality is required. Films are available in a wide range of thicknesses, colors, and finishes (smooth, structured, or printed).

Liquid coatings

Liquid coatings must meet a number of basic requirements to be successfully applied. Easy application even on the fastest production lines (up to 220m/min) to provide a homogeneous appearance and a defect-free film. For more details, please visit our website color coating process.

• Very short curing times to keep pigment colors stable - time spent in the oven can vary between 6 and 60 seconds depending on the production line, while the substrate temperature varies between 210°C and 250°C depending on the paint used.
• Flexibility to bend the coated metal without cracking or loss of adhesion of the paint film.
• Dry film thicknesses are typically between 5 and 35 microns for primers and between 15 and 200 microns for topcoats. The thickness depends on the quality of the chosen paint and the final requirements of the pre-painted metal product.

Powder Coatings

Powder coatings can be described as "solid coatings" which melt to form a continuous film on the substrate. These coatings can easily be applied by electrostatic or frictional electrostatic spraying to cover the item being painted. As the thickness of the coating increases, the coating is self-limiting and therefore a uniform film thickness can be achieved. The powder-coated article then cures as the powder melts and flows out to form a continuous film of paint followed by a chemical reaction to form a solid inert coating.

What is the best paint to use for color-coated aluminum coils?

Color-coated aluminum coils are one of the most popular decorative materials due to their stable performance and corrosion resistance. Its superior performance is attributed to the colored coating. There are four main types of paint used for aluminum at home and abroad: PVDF, acrylic paint, epoxy paint, and PE. What is the best paint for color-coated aluminum rolls? Let's find out one by one.

PVDF / FEVE - Coated Aluminum Coil

PVPD coating is a coating with fluorine resin as the main film-forming substance. Of these four coatings, PVDF coating has the best anti-aging properties and the strongest UV resistance. It also has excellent weather resistance, heat resistance, low temperature resistance, chemical resistance, unique non-stick properties, and low friction properties. Its drawback is the limited choice of colors.

PE coatings

PE, or polyester, is another type of paint widely used. Polyester paint is mainly made from polyester resins. It offers good adhesion, rich colors, excellent outdoor durability, and moderate chemical resistance. It is relatively less expensive than PVDF paints.

There are two improved polyesters, HDP and SMP. HDP has excellent color retention, UV resistance, and cost-effectiveness. SMP has good hardness, abrasion resistance, and heat resistance, but is moderately flexible and moderately cost-effective.

Acrylic pigments

Acrylic pigments are self-drying weather-resistant anti-corrosion coatings based on traditional acrylic resin with polyethylene rubber and weathering fillers and additives. They are easy to apply and cure at room temperature.

Epoxy resin paint

Epoxy resin paint consists mainly of epoxy resin and a curing agent. Epoxy paint film has good adhesion, corrosion resistance, and wear resistance, but is brittle. It is generally used as a backing paint for aluminum coils.

The choice of different paints for coated aluminum coils means that the price will vary. Therefore, it is important to choose the right paint for the application and occasion of the aluminum coil. This will ensure you get the best performance from your aluminum color-coated coils.